1 Introduction
For decades, Sodium-ion batteries (SIBs) languished in the shadow of their lithium-ion counterparts. Research on sodium intercalation into host materials emerged in the early 1980s. Professors Claude Delmas and John B. Goodenough, among others, identified key materials in the late 1980s that laid the foundation for room-temperature sodium-ion batteries [
1-
3]. Yet while lithium-ion batteries entered commercial use in the 1990s powering the portable electronics revolution and, later, the global transition to electric mobility sodium-ion research languished [
4]. The extreme dedication to lithium-ion technology eclipsed any significant development around sodium-based systems [
5]. As recently as 2025, total global SIB production constituted less than one percent of lithium-ion output. That dynamic has changed abruptly. The year 2026 marks a watershed moment. Industry consensus has crystallized around a singular claim: sodium-ion batteries have entered the era of large-scale commercialization. The International Energy Agency (IEA) has noted that sodium-ion batteries are emerging as a new player in battery markets, offering opportunities to diversify battery chemistries and supply chains at a time of rising global demand for electric vehicles and energy storage [
6-
8]. As Li Shujun, General Manager of HiNa Battery, succinctly stated, "2026 is the starting point for large-scale SIB application." This declaration is not aspirational rhetoric but a reflection of tangible industrial momentum: multiple gigawatt-hour production lines are coming online, major automakers are incorporating SIBs into vehicle platforms, and utilities are placing unprecedented orders for sodium-based stationary storage [
9]. What explains this sudden acceleration? The answer lies not in a single technological breakthrough but in a convergence of market forces, geopolitical imperatives, and maturing supply chains that has rendered the economic calculus of battery chemistry profoundly different from just three years ago.
The most immediate driver of SIB momentum has been the sustained elevation of lithium carbonate prices. Throughout the first half of 2026, battery-grade lithium carbonate has traded above RMB 200, 000 per ton more than double the cyclical lows of 2025. This price regime reflects deeper structural tensions. Lithium resources are concentrated in a handful of geographies Australia, Chile, and Argentina producing a supply chain whose fragility was exposed during the unprecedented price spike of 2022, when lithium carbonate reached 590, 000-605, 000 RMB per ton [
10]. While prices have moderated from those extremes, the geopolitical overhang remains acute. China, the world's largest battery manufacturer, sources the vast majority of its lithium from overseas, creating an uncomfortable dependence that Beijing has identified as a strategic vulnerability [
11,
12]. Compounding lithium's supply risk is copper the other metal whose price trajectory exerts powerful influence on battery economics. Copper is essential not only as a current collector material but also as a component of battery packs, electric motors, and grid infrastructure. The artificial intelligence boom has intensified demand for copper across data center construction, semiconductor fabrication, and power distribution networks. As copper prices climb toward RMB 110, 000 per ton and beyond, the cost structure of lithium-ion batteries has come under dual pressure: high-cost cathode materials plus expensive current collectors [
13-
16].
Against this backdrop of constrained and geopolitically exposed supply chains, sodium offers a compelling alternative. Sodium is the sixth most abundant element in the Earth's crust approximately 1, 000 times more abundant than lithium. Unlike lithium, which is mined from a handful of concentrated deposits, sodium is ubiquitous, extracted from seawater, salt lakes, and rock salt deposits found on every continent [
17-
19]. The International Renewable Energy Agency (IRENA) highlights that sodium is almost 60, 000 times more abundant in seawater than lithium [
20]. Widely distributed particularly along coastlines and significantly cheaper than lithium, sodium offers a compelling resource advantage. Moreover, SIBs can employ aluminum foil as the current collector for both anode and cathode, eliminating copper entirely. This design choice insulates SIB manufacturing from copper price volatility while simultaneously reducing overall material costs. As the IEA noted in its February 2026 commentary, these investments are driven primarily by the goals of improving battery performance in cold climates and reducing exposure to lithium-price volatility [
21-
24].
The case for SIBs extends beyond raw material economics. Sodium-ion batteries exhibit superior low-temperature performance relative to lithium iron phosphate (LFP) chemistries the incumbent technology in stationary storage and entry-level electric vehicles. SIBs can retain approximately 90% of nominal capacity at −40 °C, a capability that transforms the viability of battery-electric transportation in northern latitudes and cold-weather storage applications. Recent studies consistently demonstrate that sodium-ion batteries maintain superior electrochemical performance across a broad temperature range compared with conventional lithium-ion systems, highlighting their suitability for cold-climate transportation and stationary energy storage. Continued improvements in electrolyte formulations, electrode design, and cell engineering have significantly expanded the practical operating window of commercial SIBs while maintaining competitive energy density, reinforcing their growing attractiveness for applications where reliable low-temperature performance is essential [
25]. Mechanisms underlying this low-temperature resilience include optimized electrolytes that enhance ionic conductivity, stabilize interfacial chemistry, and suppress sluggish Na
+ diffusion. In safety-critical applications, SIBs demonstrate inherent stability advantages. Extreme abuse tests including compression, nail penetration, and full cutting under full charge have resulted in no fire, explosion, smoke, or thermal runaway. This safety profile is particularly valuable for grid storage and residential applications, where thermal runaway risks have constrained lithium-ion deployment. Nevertheless, SIBs are not positioned as a wholesale replacement for lithium-ion batteries. Rather, they function as an important complement, price anchor, and supply chain risk hedge" to the lithium-ion ecosystem. The techno-economic landscape is better understood as one of lithium-sodium parallelism a diversified battery chemistry portfolio in which different cell types are deployed according to their comparative advantages across cost, energy density, safety, and operating temperature requirements. This review synthesizes the current state of sodium-ion battery science and engineering at the precise moment of industrial takeoff, focusing particularly on the intersection of materials development and manufacturing scale-up a nexus that has defined SIB progress in 2026. The scope covers the techno-economic baseline of contemporary SIBs (cost analysis, market forecasts), the convergence of cathode chemistries toward layered oxides and polyanionic compounds, the central challenge of hard carbon anodes for high-volume production, the industrialization landscape with major producers' capacity announcements, emerging applications (especially energy storage), outstanding technical and market risks, and strategic implications for energy manufacturing and supply chain policy.
2 The techno-economic landscape: markets, costs, and the economics of scaling
The commercial viability of sodium-ion batteries hinges on a complex interplay of market forces, cost dynamics, and geopolitical imperatives. This section examines the techno-economic foundation of SIB industrialization, beginning with market projections that forecast extraordinary growth through 2030, followed by a detailed analysis of cost structures and the pathway to parity with incumbent lithium-ion technologies. The section then addresses the critical sensitivity of SIB economics to lithium price volatility and copper supply constraints, before concluding with an assessment of the strategic imperative for resource independence that underpins the global push for sodium-ion battery adoption. For consistency throughout this review, battery cell costs, battery pack costs, manufacturing costs, and techno-economic comparisons are expressed in USD kWh-1 unless otherwise stated. Commodity prices are reported in their original market units (e.g., RMB ton-1) with corresponding USD equivalents where appropriate.
2.1 Market projections: from GWh to hundreds of GWh
The scale of anticipated sodium-ion battery deployment over the next half-decade is extraordinary. Bernstein Research, in its June 2026 report titled "Sodium-Ion Batteries Will Disrupt the LFP Market, " estimated that global SIB shipments doubled to approximately 9 GWh in 2025 and projected an increase to at least 25 GWh in 2026 a threefold year-on-year expansion [
26]. Galaxy Securities has published even more aggressive forecasts: 25 GWh in 2026, surging to 92 GWh in 2027, 221 GWh in 2028, and ultimately exceeding 600 GWh by 2030, representing a compound annual growth rate exceeding 100% through the forecast period. These projections, while ambitious, find support in announced capacity expansions. Based on publicly disclosed project pipelines, SIB manufacturing capacity is expected to rise from approximately 20 GWh to 125 GWh, with the possibility of exceeding 500 GWh by 2030 representing roughly 10% of total global battery capacity [
27]. Citic Securities projects a 2030 market size approaching 500 GWh, disaggregated into 323 GWh for stationary storage, 152 GWh for vehicle propulsion, and 16 GWh for emerging applications including start-stop batteries and electric two-wheelers [
28]. Patent landscape analyses indicate that hard carbon remains one of the principal bottlenecks limiting large-scale commercialization of sodium-ion batteries. Although research activity and intellectual property have expanded rapidly, industrial deployment is still constrained by limited production capacity, insufficient supply-chain maturity, and inconsistent upstream standardization. These findings suggest that accelerating SIB commercialization will require coordinated investment in manufacturing infrastructure, supply-chain development, and technology transfer in addition to continued materials innovation [
29]. Analyses further demonstrate that sodium-ion battery development is closely linked to decades of accumulated lithium-ion research and manufacturing experience rather than representing an entirely independent technological pathway. Knowledge transfer is particularly strong between structurally analogous electrode materials, indicating that many existing lithium-ion-battery (LIB) processing strategies can be adapted to accelerate SIB commercialization. As shown in
Figure 1, the strongest cross-chemistry knowledge flow is observed from LIB graphite to SIB hard carbon (67.7% relative to within-structural flows). Substantial transfer also occurs between structurally analogous systems, including LIB polyanionic to SIB polyanionic (28.3%) and LIB layered oxides to SIB layered oxides (27.1%). Additionally, LIB positive electrode classes contribute notably to negative electrode counterparts (e.g., LIB layered oxides to lithium titanate (LTO) at 78.8%), underscoring the integrated nature of battery innovation across electrode types. The directional asymmetry is pronounced: SIB chemistries contribute negligibly to LIB (< 1%), whereas LIB provides considerable knowledge to SIB, with transfer intensity scaling with structural resemblance [
30].
Process-cost analyses indicate that successful industrialization of layered oxide cathodes depends not only on electrochemical performance but also on manufacturing simplicity and compatibility with existing production infrastructure. Strategies such as co-precipitation, targeted bulk modification, and optimized precursor engineering improve both process economics and material performance while minimizing additional manufacturing complexity. These approaches therefore represent practical pathways for accelerating large-scale SIB production using established industrial processing routes [
31]. Life-cycle assessments consistently indicate that sodium-ion batteries can achieve environmental impacts comparable to or lower than those of conventional lithium-ion systems, particularly as electricity grids become progressively decarbonized. Long-term analyses further suggest that sodium-ion technologies could offer meaningful cost advantages while reducing greenhouse gas (GHG) emissions, with cathode material selection becoming the dominant factor governing future environmental performance. These findings strengthen the sustainability case for large-scale SIB deployment, particularly in stationary energy storage applications [
32]. Forecasts for global battery demand indicate that LFP technology will continue to expand rapidly over the coming decades, illustrating the enormous scale of future battery deployment. Although these projections focus on lithium-based technologies, they also highlight the size of the addressable market into which sodium-ion batteries are expected to emerge as a complementary chemistry, particularly for cost-sensitive energy storage applications [
33]. Long-term projections of end-of-life battery waste further demonstrate the unprecedented expansion of global battery deployment and the growing importance of sustainable recycling strategies. Although current estimates are primarily based on lithium-ion technologies, these studies recognize that the commercial emergence of sodium-ion batteries could substantially reshape future battery waste streams and circular economy strategies as market penetration increases [
34].
2.2 Cost structure and the path to parity
The economic case for SIBs hinges on achieving cost competitiveness with LFP the lowest-cost incumbent lithium-ion chemistry. In Q1 2026, the cost landscape showed LFP cells at RMB 0.38/Wh (approximately $53/kWh) versus leading SIB producers at RMB 0.47/Wh (approximately $65/kWh). This gap of RMB 0.09/Wh represents a significant barrier, but one that is rapidly closing. Citic Securities has conducted detailed cost modeling that illuminates the pathway to parity. The analysis identifies three principal drivers of SIB cost reduction through late 2026: scaled material production delivering RMB 0.06–0.07/Wh savings; yield improvement from current levels to best-in-class lithium-ion standards, contributing RMB 0.01–0.02/Wh; and factory utilization increases reducing per-unit depreciation, labor, and energy costs by an aggregate RMB 0.04/Wh. The combined effect is expected to bring leading layered-oxide SIBs to cost parity with LFP by the end of 2026. Even accounting for a premium of RMB 0.01–0.02/Wh at the pack level due to initial manufacturing inefficiencies, the analysis concludes that 2027 will mark the beginning of the "parity era" for SIBs [
28]. International analysts have reached similar conclusions. Bernstein's assessment indicates that SIB cost fell from $75/kWh to $57/kWh during 2025 alone a 24% reduction. The firm projects SIB costs will undercut nickel–manganese–cobalt (NMC) by 2026 and LFP by 2027, ultimately achieving a $15–20/kWh advantage over LFP at scale. Other estimates place SIB prices in the $70–100/kWh range as of 2026, closely approaching the $70–80/kWh range of LFP cells. Life-cycle assessments consistently indicate that sodium-ion batteries offer environmental advantages over conventional lithium-ion technologies during manufacturing, although the magnitude of these benefits depends strongly on regional electricity generation mixes. As battery production becomes increasingly powered by low-carbon electricity, the environmental footprint of SIB manufacturing is expected to decline further, strengthening the sustainability case for large-scale commercialization. These analyses also highlight that cathode production remains the dominant contributor to manufacturing emissions, emphasizing the importance of materials selection alongside cost optimization in future industrial development [
35]. Vehicle-level techno-economic analyses further suggest that sodium-ion batteries can provide a competitive ownership-cost advantage for electric vehicles despite their lower energy density relative to conventional lithium-ion chemistries. Current evidence indicates that SIBs are particularly well suited to vehicles with small- to medium-sized battery packs, where lower cell costs outweigh modest reductions in driving range. These findings reinforce the emerging market position of sodium-ion technology as a cost-driven solution for entry-level electric vehicles and urban mobility rather than as a direct replacement for high-energy-density lithium-ion systems [
36].
2.3 The lithium price scenario and market timing
SIB economics are exquisitely sensitive to the price of lithium carbonate. At current elevated levels (RMB 200, 000/ton, approximately $28, 000/ton), the cost advantage of sodium over lithium is manifest. However, lithium markets have historically demonstrated extreme volatility, and a sustained decline could compress the economic window for SIB adoption. Citic Securities has identified a scenario in which lithium carbonate falls below RMB 50, 000/ton (approximately $7, 000/ton) as a material risk to SIB commercialization timelines, as this would substantially erode the cost advantage over incumbent LFP technology. The copper price serves as a second critical variable. SIBs eliminate copper entirely from the cell, whereas LFP cells require copper foil for the anode current collector. In a scenario where copper reaches RMB 110, 000/ton ($15, 500/ton), LFP cell costs would rise to RMB 0.42/Wh, widening the cost window for SIB adoption regardless of lithium price movements. The concurrent pressures of AI-driven demand and supply constraints on copper mining suggest that elevated copper prices are likely to persist, providing structural support to SIB competitiveness. Recent economic analyses consistently identify lithium price volatility as one of the principal uncertainties influencing the commercial trajectory of sodium-ion batteries. The unprecedented surge in lithium carbonate prices during 2020–2022 exposed the vulnerability of lithium-dependent supply chains and demonstrated how rapidly increasing raw material costs can disrupt battery economics and electric vehicle affordability. Although future lithium prices are expected to stabilize as additional mining capacity enters the market, these studies suggest that lithium-free technologies such as sodium-ion batteries provide an effective strategic hedge against future supply disruptions and commodity price fluctuations, particularly for applications where ultra-high energy density is not essential [
37].
Broader assessments of critical material supply chains further demonstrate that sustained increases in the prices of lithium, cobalt, nickel, and other battery metals could substantially slow electric vehicle adoption while increasing cumulative transport-sector carbon emissions. These findings reinforce the importance of diversifying battery chemistries and reducing dependence on vulnerable critical mineral supply chains. In this context, sodium-ion batteries represent not only a lower-cost alternative under favorable market conditions but also a strategic option for improving long-term resource security and supply-chain resilience [
38].
Figure 2 summarizes the relationship between critical material price evolution, battery manufacturing costs, and vehicle economics, illustrating how sustained raw material price increases can strengthen the commercial rationale for sodium-ion battery deployment.
Supply-chain assessments further indicate that reducing dependence on critical raw materials has become a strategic priority for the long-term expansion of the battery industry. Scenario analyses suggest that broader adoption of alternative chemistries, including sodium-ion batteries, could substantially alleviate demand for lithium, cobalt, and nickel while improving the resilience of regional battery supply chains. These studies also emphasize that technology diversification, together with effective circular economy and recycling strategies, will play a central role in mitigating future raw material constraints and strengthening battery manufacturing independence, particularly within the European Union [
39].
2.4 Resource independence: the strategic imperative
Beyond pure cost arithmetic, SIB adoption is being propelled by strategic considerations that transcend quarterly financial metrics. China's dependence on imported lithium 80% of supply originates overseas represents a national security vulnerability that Beijing is actively seeking to mitigate. Sodium, by contrast, can be sourced entirely from domestic deposits, offering not only cost stability but also supply chain resilience against geopolitical disruption. This strategic dimension has accelerated policy support for SIB industrialization. While direct subsidies remain limited, demonstration projects such as the Hubei Honghu and Jiangsu Rudong grid-scale storage facilities have received government backing, and standardization efforts are underway to establish technical specifications for SIB deployment across China's rapidly expanding energy storage sector. The International Energy Agency, in its analysis of SIB momentum, explicitly cited "goals of improving battery performance in cold climates and reducing exposure to lithium-price volatility" as the primary drivers of recent investment. Recent geopolitical analyses indicate that competition for critical minerals has become a defining factor shaping future battery supply chains. Growing strategic rivalry over lithium, cobalt, rare earth elements, and other critical materials has reinforced the need to diversify battery chemistries and reduce dependence on geographically concentrated mineral resources. In this context, sodium-ion batteries offer a strategic complement to lithium-based technologies by improving resource security while reducing exposure to geopolitical supply disruptions [
40]. Similar assessments of the European battery sector emphasize that long-term competitiveness depends not only on expanding cell manufacturing capacity but also on strengthening raw material security and supply-chain resilience. Current policy initiatives therefore prioritize resource diversification, domestic processing capacity, recycling infrastructure, and continued development of alternative battery chemistries, with sodium-ion batteries identified as an important pathway for reducing dependence on imported lithium, cobalt, and nickel [
41].
Supply-chain assessments from the United States likewise highlight widening gaps between future critical mineral demand and secure domestic supply. These studies emphasize that strengthening refining capacity, diversifying supply sources, and accelerating innovation in alternative battery chemistries will be essential for reducing long-term dependence on geopolitically concentrated mineral resources and enhancing national energy security [
42]. Policy analyses further demonstrate that increasing competition for critical transition minerals is reshaping national resource strategies across major economies. As governments seek to secure reliable access to strategic materials through regulatory reforms and international partnerships, diversification toward battery chemistries with lower critical mineral dependence has emerged as an important approach for improving long-term supply security [
43].
In addition to economic and geopolitical considerations, social life-cycle assessments indicate that sodium-ion batteries generally exhibit lower social risk than conventional lithium-ion systems, as they avoid extensive reliance on cobalt- and lithium-intensive supply chains. Reduced dependence on geographically concentrated critical minerals mitigates risks associated with labour practices and resource governance, thereby strengthening the broader sustainability case for sodium-ion technology. As illustrated in
Figure 3, the comparative social impact assessment reveals consistently lower social risk across most evaluated categories, reinforcing the strategic importance of resource diversification in future battery manufacturing [
44].
Trade-network analyses further reveal that conventional assessments often underestimate vulnerabilities associated with critical mineral supply chains because they overlook embedded import dependencies. These findings identify cobalt, nickel, and lithium as persistent sources of strategic risk and reinforce the importance of battery chemistry diversification, recycling, and international supply-chain development for improving long-term resource security [
45]. Recent supply-risk assessment frameworks similarly demonstrate that concentrated production of critical battery minerals substantially increases geopolitical exposure and supply-chain fragility. Incorporating production diversity and political risk into competition analyses further strengthens the case for alternative battery chemistries capable of reducing dependence on highly concentrated mineral markets [
46]. Broader evaluations of global energy supply chains likewise conclude that complete de-risking from existing critical mineral value chains remains difficult despite ongoing diversification efforts. These observations emphasize the importance of complementary strategies, including battery chemistry diversification, to improve resilience while reducing long-term dependence on concentrated mineral supply networks [
47].
System-level analyses of China's lithium supply chain further indicate that future resource security will be driven primarily by rapidly growing battery demand rather than geological resource availability alone. These findings strengthen the strategic rationale for complementary battery technologies capable of moderating lithium demand while improving long-term supply-chain resilience [
48]. National resource security strategies increasingly emphasize resilient supply chains, resource conservation, international cooperation, and technology diversification as essential components of long-term energy security. Within this framework, sodium-ion batteries represent an important complementary technology for reducing dependence on imported critical minerals while supporting more sustainable resource management [
49].
The techno-economic landscape of sodium-ion batteries is described in
Table 1, which presents key performance indicators, cost metrics, environmental footprints, and supply risk assessments across various battery chemistries. As shown in the
Table 1, SIBs demonstrate competitive cell prices ($54–62/kWh for NaNi
1/3Fe
1/3Mn
1/3O
2 (NaNFM) 111 SIB) compared to LFP ($56–62/kWh) and NMC811 (
111116B to $44B by 2031) and the substantial European energy demand (250 TWh annually by 2050) required to establish domestic battery cell production.
Table 1 summarizes the techno-economic, environmental, and supply-chain characteristics of sodium-ion and lithium-ion battery systems. These metrics demonstrate that sodium-ion batteries have become increasingly competitive in manufacturing cost, environmental performance, and critical material security, supporting their emergence as a complementary battery technology for large-scale energy storage and cost-sensitive transportation applications.
3 Cathode chemistry: convergence and divergence
The performance of sodium-ion batteries is fundamentally determined by the cathode material, which governs energy density, cycling stability, and cost. This section examines the three mainstream cathode families layered transition metal oxides, polyanionic compounds, and Prussian Blue analogue (PBA) that have emerged as the primary contenders for SIB commercialization. The analysis begins with an overview of each material platform's intrinsic advantages and limitations, followed by a detailed examination of recent advances in performance optimization through doping, morphology control, and structural engineering. The section then explores the industrial convergence toward two dominant routes layered oxides for mobility applications and polyanionic compounds for stationary storage while acknowledging the persistent challenges that have hindered PBA from achieving comparable commercial momentum. Finally, manufacturing implications are discussed, highlighting how existing lithium-ion production infrastructure is being utilized to accelerate SIB cathode industrialization.
3.1 The three contenders
Sodium-ion cathode development has historically been characterized by three distinct material platforms, each optimized for different points on the cost-energy-safety triangle. Three cathode families layered transition metal oxides, polyanionic compounds, and PBAs have emerged as the dominant material platforms for sodium-ion batteries because they offer distinct balances between energy density, cost, safety, and cycle life. Recent studies indicate that continued optimization of each cathode family through compositional tuning and structural engineering will be essential for translating laboratory-scale advances into commercially viable sodium-ion technologies, particularly for large-scale energy storage applications [
59]. PBA, typically formulated as Na
2Fe[Fe(CN)
6] or variants with manganese, cobalt, or nickel substitution, feature an open-framework crystal structure with three-dimensional ion diffusion channels, enabling exceptionally high-rate capability. The material exhibits minimal structural strain during cycling (volume change less than 2%, compared with approximately 7% for layered oxides) and relies on low-cost, abundant iron-based chemistry that eliminates cobalt and nickel entirely. The principal challenge for PBAs has been controlling interstitial water content residual water molecules within the crystal structure degrade electrochemical performance and cycle life. Layered Transition Metal Oxides, with general formula Na
XTMO
2 (where TM represents transition metals such as Mn, Fe, Ni, Co, or Cu), offer the highest practical energy densities among SIB cathodes, typically exceeding 160 Wh/kg at the cell level and approaching 180 Wh/kg in advanced formulations. Their layered structure allows facile sodium intercalation and deintercalation, but they suffer from phase transitions during cycling that can accelerate capacity fade. The presence of nickel in many high-performance formulations reintroduces cost and supply chain concerns that SIBs were intended to avoid. Polyanionic Compounds, including sodium iron phosphate (NaFePO
4) and sodium vanadium phosphate (Na
3V
2(PO
4)
3), offer exceptional thermal stability and cycle life exceeding 10, 000 cycles in optimized systems, making them particularly attractive for stationary storage applications where calendar and cycle life are critical. The trade-off lies in lower electronic conductivity relative to layered oxides, necessitating carbon coating or nanostructuring to achieve acceptable rate performance.
Characterization of commercially available 18650 sodium-ion cells has provided valuable insight into the structural design principles currently adopted for industrial SIBs. These studies confirm that layered oxide cathodes coupled with hard carbon anodes have become the preferred commercial configuration because they provide a practical balance between energy density, structural stability, and manufacturability. Operando structural analyses further demonstrate that the reversible phase evolution of layered oxide cathodes during cycling can be accommodated without catastrophic structural degradation, supporting their suitability for repeated charge-discharge operation under practical conditions. The identification of residual processing species also highlights the importance of optimizing electrode manufacturing and materials processing as commercialization advances [
60].
Figure 4 represent the structural characterization of a commercial sodium-ion cell and illustrates how the combined cathode and anode architecture supports reversible electrochemical operation while providing insight into manufacturing-related features relevant to industrial cell development.
Synthesis conditions play a decisive role in determining the crystal structure and electrochemical performance of PBA cathodes. Controlled coprecipitation and heat-treatment temperatures enable phase evolution and microstructural optimization, resulting in substantial improvements in specific capacity and overall electrochemical performance [
61]. Density functional theory further indicates that Ti substitution improves structural stability, widens sodium-ion diffusion pathways, and enhances electronic conductivity through favorable electronic structure modulation. These findings demonstrate that targeted cation substitution represents an effective strategy for improving the electrochemical performance of layered oxide cathodes [
62].
Figure 5 illustrates the electronic structure modifications associated with Ti incorporation, highlighting the enhanced orbital hybridization responsible for improved charge transport. Halogen doping has emerged as an effective strategy for improving the electrochemical performance of polyanionic cathodes. Chlorine incorporation into Na
3V
2(PO
4)
2O
2F modifies the local electronic environment, accelerates sodium-ion diffusion, reduces charge-transfer resistance, and significantly improves both rate capability and long-term cycling stability [
63]. The long-term degradation of PBA cathodes arises from coupled structural and interfacial degradation processes. Multifunctional electrolyte additives can simultaneously stabilize crystalline water and passivate framework defects, thereby significantly improving cycling stability and high-rate performance. These findings highlight electrolyte engineering as an effective strategy for enhancing the commercial durability of PBA cathodes [
64].
3.2 Convergence: two dominant routes
As SIBs have advanced from laboratory research to industrial production, the proliferation of cathode chemistries has begun to converge. The market has gravitated toward two dominant routes, each aligned with specific application domains. Layered oxides have emerged as the preferred chemistry for mobility applications low-speed EVs, two-wheelers, and start-stop systems where energy density is paramount. Contemporary Amperex Technology Co., Limited (CATL) and Build Your Dreams (BYD), the two largest battery manufacturers globally, have both prioritized layered oxide chemistries for their initial SIB product launches. The material can be produced on existing NMC manufacturing lines with relatively minor modifications, dramatically reducing the capital expenditure required for initial capacity build-out. Polyanionic compounds have established a stronghold in stationary energy storage, where the premium on cycle life outweighs energy density considerations. Companies including Veken Technology have made significant progress in polyanionic SIB commercialization, targeting the utility-scale storage market. The third route PBA have struggled to achieve the same industrial momentum despite promising laboratory performance. The challenges of interstitial water control at manufacturing scale have proved formidable, though recent patent activity suggests continued R&D investment in PBA systems. PatSnap's analysis of the patent landscape reveals 7, 032 SIB-related patent filings in 2024 a 12-fold increase from the 2017 baseline of 580-640 filings per year with substantial activity across all three cathode families. Among polyanionic compounds, vanadium-based cathodes have been extensively studied [
65].
Comparative evaluation of vanadium-based polyanionic cathodes indicates that solid-solution materials generally provide superior capacity retention and energy density at high rates and low temperatures compared with phase-transforming counterparts. These findings emphasize the importance of minimizing phase-boundary limitations when designing high-power polyanionic cathodes for stationary energy storage [
66]. Structural engineering of Cu-Mn-Fe PBA has demonstrated that compositional optimization can simultaneously improve capacity, cycling stability, and temperature adaptability. The successful operation of 18650-format cells further confirms that carefully engineered PBA cathodes have the potential to meet practical requirements despite the manufacturing challenges traditionally associated with this material family [
67]. Dual transition-metal and fluorine doping has proven effective for enhancing the electronic conductivity, sodium-ion diffusion kinetics, and structural stability of polyanionic cathodes. The resulting improvements in rate capability, long-term cycling stability, and wide-temperature operation further strengthen the suitability of these materials for stationary energy storage applications [
68]. Site-selective co-doping has emerged as an effective strategy for stabilizing P2-type layered oxide cathodes. Incorporation of La and Ti suppresses detrimental phase transitions, strengthens transition-metal-oxygen bonding, and improves high-voltage cycling stability, demonstrating how compositional engineering can unlock the full energy-density potential of layered oxides for mobility applications [
69]. Careful compositional optimization remains essential for balancing phase stability and electrochemical performance in layered oxide cathodes. Ti substitution suppresses detrimental P
2-O
2 phase transitions, although excessive substitution promotes cation migration and reduces structural reversibility, highlighting the importance of precise transition-metal engineering for commercial layered oxide systems [
70]. The rate capability of polyanionic cathodes is governed primarily by sodium-ion migration barriers, diffusion dimensionality, and the availability of energetically favorable migration pathways. Structure-property analyses demonstrate that NASICON-type frameworks consistently outperform one-dimensional channel structures because their three-dimensional diffusion networks facilitate rapid sodium transport. As illustrated in
Figure 6, this structural advantage explains why NASICON-type and pyrophosphate cathodes have emerged as leading candidates for high-power stationary energy storage [
71].
High-valence Nb doping combined with conductive graphene networks has been shown to enhance the intrinsic electronic conductivity and sodium-ion diffusion of NaV
2(PO
4)
2O
2F cathodes. This synergistic modification substantially improves both rate capability and long-term cycling stability, highlighting the effectiveness of coupled compositional and conductive-network engineering for polyanionic cathodes [
72]. Tuning of cyanide coordination electronic structure to enable stable PBA was investigated by Wang et al. (2025). By modulating the local electronic structure surrounding nitrogen-coordinated transition metal ions (MHS), a uniform electron distribution was created within the PBA framework, enhancing the reactivity of both nitrogen-coordinated and carbon-coordinated transition metals. The optimized M4-PBA (with equimolar Mn, Fe, Co, Ni) achieved a capacity retention of over 91% at 5C after 1000 cycles with an initial discharge capacity of 142.4 mAh g
-1 at 0.1C. The uniform cyanide electronic distribution simultaneously improved Fe-C≡N-M coordination structural stability and reduced Na
+ migration barriers, demonstrating that electronic structure engineering can overcome the historical challenges of PBA cycling stability [
73].
3.3 Manufacturing implications
A major advantage of SIB technology is its ability to leverage the mature manufacturing infrastructure developed for LIBs. Rather than requiring entirely new production facilities, most early industrial SIB manufacturing has been implemented by adapting existing LIB production lines originally designed for layered oxide or LFP cathodes, with only modest modifications to accommodate sodium-specific material characteristics. This co-line manufacturing strategy has substantially reduced the capital investment required for commercialization while enabling rapid transition from laboratory-scale development to industrial production. As manufacturing volumes continue to increase toward the multi-gigawatt-hour scale, dedicated SIB production facilities are expected to further improve production efficiency, process optimization, and manufacturing economics. CATL's investment in a dedicated 40 GWh sodium-ion production line represents the first large-scale commitment to purpose-built SIB manufacturing infrastructure, illustrating the industry's transition from pilot-scale adaptation toward specialized mass production. The scalability of SIB manufacturing depends not only on existing production infrastructure but also on synthesis routes that consistently deliver high-quality cathode materials. Among the available approaches, hydroxide coprecipitation has emerged as the leading manufacturing strategy for layered oxide cathodes because it enables continuous production, precise particle morphology control, and compatibility with established industrial processes. Nevertheless, sodium layered oxides remain more difficult to manufacture than their lithium counterparts owing to the strong interdependence of synthesis parameters, including pH, temperature, chelation chemistry, stirring conditions, and residence time. In situ characterization during synthesis has therefore become an important tool for optimizing nucleation, crystal growth, and calcination conditions, thereby improving production reproducibility and material quality during large-scale manufacturing [
74,
75]. In parallel, scalable hydrothermal synthesis has demonstrated considerable promise for producing polyanionic cathodes. One-step hydrothermal processes offer excellent reproducibility, environmentally benign processing, and kilogram-scale production while maintaining competitive electrochemical performance, demonstrating that manufacturing scalability can be achieved without sacrificing battery performance [
76]. Beyond precursor synthesis, electrode processing has emerged as one of the most critical challenges for industrial implementation of sodium layered oxide cathodes. Owing to their high surface alkalinity, these materials readily undergo undesirable reactions with water during slurry preparation, resulting in sodium leaching, structural degradation, slurry gelation, and poor coating quality. Liquid-phase dealkalization using ethylene glycol (EG) has recently been shown to effectively remove residual surface alkali while avoiding the structural degradation associated with conventional aqueous washing [
77]. From an industrial perspective, these findings substantially strengthen the "drop-in" manufacturing potential of sodium-ion batteries. As illustrated in
Figure 7, EG-assisted dealkalization suppresses slurry gelation, enables uniform electrode coating, and preserves cathode structural integrity throughout slurry preparation and electrode fabrication. These improvements significantly enhance the compatibility of sodium layered oxide cathodes with conventional LIB mixing, coating, drying, and calendaring equipment, allowing manufacturers to adapt existing production lines with relatively minor process modifications rather than constructing entirely new manufacturing facilities. Nevertheless, EG-assisted dealkalization does not eliminate the need for moisture management during manufacturing. Although the improved slurry stability enables processing on conventional LIB coating lines, sodium-based cathodes remain more moisture-sensitive than many commercial lithium-ion materials. Consequently, humidity-controlled (dry-room) environments are still recommended during critical processing and storage steps to ensure consistent material quality and electrochemical performance. Consequently, current evidence indicates that sodium-ion battery manufacturing can largely capitalize on existing LIB production infrastructure while requiring only targeted process optimization instead of fundamental changes to manufacturing technology, thereby reducing capital investment and accelerating commercial deployment.
Recent advances have focused on scalable synthesis strategies that improve structural homogeneity, manufacturing efficiency, and industrial reproducibility. Tuning the sodium precursor chemistry has been shown to improve particle uniformity, suppress impurity formation, and enhance cycling stability, demonstrating that simple modifications to precursor selection can provide an effective and scalable route for optimizing layered oxide cathodes [
78]. High-throughput synthesis has further accelerated materials discovery by enabling rapid screening of complex compositional spaces, while also demonstrating that sol-gel processing is more effective than conventional coprecipitation for producing phase-pure Na-Fe-Mn oxides, highlighting the need for sodium-specific manufacturing strategies rather than direct adaptation of lithium-ion synthesis routes [
79]. Industrial scalability has also been improved through optimized coprecipitation, ultrafast emulsion synthesis, and low-temperature processing, enabling high-capacity cobalt-free cathodes, significantly shorter synthesis times, and successful kilogram-scale production without compromising electrochemical performance [
80-
82]. Importantly, practical validation in Ah-scale soft-pack cells demonstrates that these manufacturing approaches are compatible with commercial battery production. Furthermore, comparisons of different milling strategies indicate that maximizing phase purity does not always produce the best electrochemical performance, emphasizing the importance of balancing structural quality with manufacturing practicality [
83]. The electrochemical performance of representative sodium-ion cathodes is summarized in
Table 2. Layered oxides generally provide the highest capacities and excellent rate capability for mobility applications, whereas polyanionic compounds exhibit superior long-term cycling stability suitable for stationary energy storage. Continued improvements in PBA further demonstrate that advances in synthesis and process engineering are steadily improving their commercial competitiveness.
4 Anode challenge: hard carbon at the heart of scale-up
The anode represents the most fundamental divergence between lithium-ion and sodium-ion battery chemistries. While graphite serves as the universal anode material for lithium-ion batteries, its layered structure cannot accommodate the larger ionic radius of sodium, forcing sodium-ion battery developers to identify alternative anode materials. This section examines why graphite fails for sodium storage, explores hard carbon as the dominant solution, discusses the scaling challenges that must be overcome for commercial viability, and reviews emerging research frontiers in fast-charging hard carbon anodes.
4.1 Why graphite fails for sodium
The most fundamental difference between lithium-ion and sodium-ion battery chemistry lies in the anode. Graphite the universal anode material for LIBs is essentially inactive for sodium intercalation because the ionic radius of Na
+ (1.02 Å) is approximately 55% larger than that of Li
+ (0.76 Å). This size mismatch prevents stable intercalation into the layered structure of graphite, forcing SIB developers to identify alternative anode materials. Expanded graphite has been investigated as a potential strategy for overcoming the limitations of pristine graphite during sodium storage. Theoretical analyses indicate that enlarging the graphite interlayer spacing can significantly improve sodium intercalation by providing thermodynamically favorable diffusion pathways within an optimal d-spacing range, thereby offering valuable design guidelines for carbon-based SIB anodes [
98]. The failure of graphite during reversible Na
+ ion storage was investigated by Dey and Singh (2023), who compared surface-functionalized graphene oxide (GO) and nanostructured graphene nanoplatelets (GNP) as alternative carbon anodes. Graphite exhibited negligible Na
+ storage with only 27 mAh g
-1 after 60 cycles, while GO achieved 157 mAh g
-1 and GNP achieved 50 mAh g
-1. Electrochemical impedance spectroscopy revealed that graphite's low capacity correlated with high impedance from SEI formation and charge transfer. GO's superior performance was attributed to oxygen functional groups that expand interlayer spacing and reduce the energy barrier for Na
+ insertion (0.053 eV), while GNP's moderate performance derived from nanostructuring providing additional active sites. This study confirms that pristine graphite fails as a SIB anode, while surface functionalization and nanostructuring of carbon materials can significantly enhance Na
+ storage [
99]. First-principles calculations provide a fundamental explanation for graphite's poor sodium-storage capability. Unlike lithium, which forms partially covalent interactions with graphite that stabilize intercalation compounds, sodium interacts predominantly through weaker ionic bonding while simultaneously imposing greater structural distortion. The combination of weaker bonding and higher deformation energy prevents the formation of stable sodium-graphite intercalation compounds under normal operating conditions [
100]. Long-term experimental investigations have confirmed that sodium intercalation into graphite is intrinsically limited by both thermodynamic instability and sluggish diffusion kinetics. Although elevated temperatures can modestly increase sodium uptake, reversible intercalation remains extremely limited under practical battery operating conditions.
Figure 8 summarizes the experimental approaches used to distinguish intrinsic sodium intercalation from solvent co-intercalation, demonstrating that the poor sodium-storage behavior of graphite arises from the fundamental characteristics of the graphite lattice rather than experimental artifacts [
101]. Density functional theory (DFT) calculations with van der Waals functionals were used by Moriwake et al. (2017) to systematically evaluate the stabilities of alkali metal-graphite intercalation compounds (Li, Na, K, Rb, Cs). Na-graphite intercalation compounds are thermodynamically unstable for all concentrations examined (stages 1 to 12), with positive formation energies across the entire range. Critically, Na actually conforms to the expected intercalation behavior extrapolated from larger alkali metals (K, Rb, Cs), where ionic bonding weakens as ion size decreases, making formation energies less negative. It is Li that is the exception not Na because Li-C bonds contain a non-negligible covalent component from orbital overlapping that stabilizes the intercalated compound. Electron density maps confirmed significant electron sharing between C and Li atoms, while Na-C and K-C bonds are purely ionic with negligible electron density between atoms. This explains why graphite is a good intercalation material for Li and K, but not for Na [
102].
4.2 Hard carbon: the dominant solution
Hard carbon has emerged as the clear anode material of choice for commercial SIBs. This disordered carbon structure features randomly stacked graphene layers and microporous voids that accommodate sodium ions through a combination of intercalation, pore filling, and surface adsorption mechanisms. Hard carbon offers high reversible specific capacity (300-400 mAh/g), excellent cycle stability, and a low sodiation potential that maximizes cell voltage. The current industry standard relies on biomass-derived hard carbon, typically produced from coconut shells, starch, straw, or other agricultural residues. Biomass precursors offer the advantages of abundant availability and established processing routes. However, they introduce significant challenges: batch-to-batch consistency is notoriously difficult to control due to natural variation in precursor composition, and impurity levels can be problematic. Leading producers have made substantial progress in addressing these consistency issues. CATL and BYD have both achieved yield rates exceeding 95% on their hard carbon anode lines after overcoming what the industry terms the "hard carbon gas evolution problem" the tendency of disordered carbon structures to generate gas during initial formation cycling. One of the principal challenges for biomass-derived hard carbon is achieving high initial coulombic efficiency while maintaining excellent rate capability. Closed-pore engineering through combined pre-oxidation and chemical vapor deposition has proven effective in reducing surface defects, optimizing pore structure, and significantly improving the electrochemical performance of biomass-derived hard carbon, demonstrating a viable pathway toward commercial anode production [
103]. Atomic-scale modeling has significantly advanced the understanding of sodium storage in hard carbon by confirming the combined contributions of sodium adsorption, interlayer intercalation, and closed-pore filling. These mechanistic insights provide valuable guidance for designing hard carbon microstructures with improved reversible capacity and higher initial coulombic efficiency [
104]. A green and scalable strategy for sustainable production of high-capacity hard carbon from lignocellulosic biomass was proposed by Lu et al. (2026), coupled with coproduction of value-added sugars. The study first fractionated industrial lignin using recyclable ethyl acetate to identify target-structured lignin with high β-O-4 ether linkage content, high molecular weight, and few reactive functional groups. After carbonization, the extracted lignin exhibited a disordered microstructure with enlarged interlayer spacing and abundant closed nanopores, delivering superior sodium storage performance. The technique enables full utilization of biomass components, achieving utilization efficiencies of 78.6% for lignin, 93.0% for hemicellulose, and 83.8% for cellulose from bamboo powder [
105].
Microstructural regulation through precursor engineering has shown that balancing closed and open pore populations is essential for optimizing hard carbon performance. While closed pores maximize reversible capacity, open pores facilitate sodium-ion transport, indicating that commercial hard carbon requires a carefully balanced pore architecture rather than maximizing either feature alone [
106]. Fragmentation-reconstruction strategies have also demonstrated that controlled restructuring of naturally stacked carbon frameworks effectively generates closed-pore-rich hard carbon with substantially improved reversible capacity and initial coulombic efficiency, highlighting another promising route for scalable hard carbon production [
107]. Direct observations of hard carbon formation during pyrolysis have demonstrated that the processing atmosphere strongly influences the resulting microstructure and electrochemical performance. Nitrogen-assisted pyrolysis favors the formation of disordered carbon with abundant closed micropores and low surface area, leading to higher plateau capacity and improved initial coulombic efficiency compared with vacuum processing [
108]. Heteroatom co-doping combined with controlled pore engineering has emerged as another effective strategy for improving biomass-derived hard carbon. Simultaneous optimization of interlayer spacing, closed-pore content, and electronic structure enables exceptionally high reversible capacity, excellent initial coulombic efficiency, and long-term cycling stability, demonstrating the potential of waste-derived precursors for sustainable commercial anode production [
109].
Combining soft and hard carbon through heteroatom co-doping provides an effective approach for simultaneously improving electronic conductivity, sodium-ion transport, and structural stability. These synergistic effects contribute to enhanced reversible capacity and cycling performance while expanding the range of viable industrial carbon precursors [
110]. Surface coating with petroleum-pitch-derived soft carbon has also proven effective for overcoming the low initial coulombic efficiency that commonly limits biomass-derived hard carbons. Surface modification reduces defect density and oxygen-containing functional groups while increasing graphitic carbon content, thereby significantly improving electrochemical efficiency without sacrificing reversible capacity [
111]. Structure-property investigations further demonstrate that sodium storage in hard carbon depends on the coordinated evolution of graphite-like layers and closed pores during carbonization. These studies clarify that interlayer sodium insertion precedes efficient closed-pore storage, providing an important mechanistic framework for rational hard carbon design and optimization [
112,
113]. Nitrogen-oxygen co-doped carbon nanotubes further illustrate how defect engineering and controlled microstructure can shift sodium storage toward rapid surface-controlled processes, enabling outstanding rate capability and exceptionally long cycling stability. These findings demonstrate that controlled defect chemistry remains an important strategy for fast-charging sodium-ion battery anodes [
114].
From an industrial perspective, biomass- and pitch-derived hard carbons represent two complementary commercialization pathways rather than competing technologies. Biomass-derived hard carbons benefit from abundant renewable feedstocks and lower raw material costs, but their inherent structural variability and gas evolution during carbonization present challenges for batch-to-batch consistency and process control. In contrast, pitch-derived hard carbons provide greater precursor homogeneity, predictable microstructure, and superior manufacturing reproducibility, making them well suited for large-scale industrial production. However, these advantages are offset by their dependence on petroleum-derived feedstocks and the higher energy consumption associated with high-temperature calcination. Consequently, future commercial deployment will depend on balancing sustainability, manufacturing consistency, energy efficiency, and production cost according to the requirements of specific sodium-ion battery applications.
4.3 Scaling Challenges and Alternative Routes
The transition from laboratory-scale to gigawatt-scale hard carbon production remains one of the most formidable challenges in SIB manufacturing. Current production methods are energy-intensive and yield-dependent, with material costs currently constraining SIB competitiveness against LFP. Pitch-based hard carbon offers potentially lower cost and more consistent quality than biomass-derived material, particularly as production scales beyond 10 GWh of annual demand. Pitch a carbonaceous residue from petroleum or coal processing can be processed into hard carbon with controlled pore architecture. However, the environmental footprint of pitch processing is substantial, and qualification cycles for new source materials are lengthy. Anode-free designs represent the most radical departure from conventional architectures. By eliminating the anode current collector and active material entirely, anode-free cells could dramatically reduce cost while increasing energy density by dedicating more mass and volume to active cathode material. Gotion High-Tech has embraced this approach with its "Na-Chen" battery, which employs a novel anode-free structure combined with multi-stage pre-sodiation technology. Nevertheless, anode-free designs face fundamental challenges: non-uniform sodium deposition leads to dendrite formation and premature cell failure, while SEI instability compromises cycle life. These issues remain unresolved at commercial scale. Controlled oxidation pretreatment has proven effective for regulating the microstructural evolution of pitch-derived hard carbon during carbonization. Optimized processing expands interlayer spacing, enhances structural disorder, and significantly improves both rate capability and long-term cycling stability, demonstrating the promise of pitch-derived hard carbon as a scalable commercial anode material [
115]. A comprehensive life cycle assessment of bio-based hard carbon production across different scales from laboratory to pilot and industrial production was conducted by Liu et al. (2024) using primary data from two laboratories. Pyrolysis was identified as the dominant contributor to environmental footprint, accounting for up to 98% of energy consumption. Scale-up from laboratory (10 g/batch) to industrial scale (1000 kg/batch) reduced global warming potential (GWP) by over 265-fold. The hypothetical industrial best-case scenario demonstrated that HC can achieve GWP comparable to graphite at scale. The system boundary of the life cycle assessment encompasses the cradle-to-gate production of hard carbon, including the supply chain of raw materials, pre-treatment (washing, drying, grinding), pyrolysis, and post-treatment (ball milling, scrubbing) are shown in
Figure 9, which highlights the primary production steps acid treatment and pyrolysis as the key stages where environmental impacts are concentrated, with pyrolysis accounting for up to 98% of energy consumption [
116].
Pre-oxidation strategies applied to biomass-derived hard carbon effectively regulate carbon framework evolution during carbonization, producing more favorable pore structures while reducing defect density. These microstructural improvements substantially enhance both reversible capacity and initial coulombic efficiency, further strengthening the commercial potential of waste biomass as an anode precursor [
117]. Careful control of carbonization conditions has also enabled the production of biomass-derived hard carbon with exceptionally high initial coulombic efficiency. Optimizing pseudo-graphitic layer development and closed-pore formation provides an effective route toward simultaneously improving reversible capacity and first-cycle efficiency without requiring additional conductive additives [
118]. Co-pyrolysis of industrial carbon precursors has emerged as another practical strategy for producing high-performance hard carbon with excellent reversible capacity and exceptionally high initial coulombic efficiency. These results further demonstrate the potential of industrial waste streams as scalable feedstocks for sodium-ion battery anodes [
119]. Intramolecular oxidation has also proven effective for converting mesophase pitch into high-performance hard carbon by promoting favorable microstructural evolution during carbonization. This approach substantially improves reversible capacity, low-voltage plateau contribution, and cycling stability, highlighting its promise for commercial pitch-derived hard carbon production [
120].
Sacrificial structural modifiers such as ZnO have been successfully employed to regulate carbon evolution during pyrolysis, simultaneously generating controlled porosity and reinforcing the carbon framework. This dual-function strategy further improves reversible capacity while maintaining structural stability during cycling [
121]. Precise control of pre-oxidation and carbonization has demonstrated that coordinated regulation of defects, interlayer spacing, and pore architecture enables simultaneous optimization of sodium-ion diffusion and storage thermodynamics. Importantly, this strategy has already been validated in Ah-level 18650 cylindrical cells, demonstrating its practical scalability for commercial sodium-ion battery production [
122]. Machine learning has recently emerged as a powerful tool for accelerating hard carbon development by linking precursor composition, processing conditions, microstructure, and electrochemical performance. Predictive models identify the combinations of structural disorder, interlayer spacing, and carbon domain size that maximize reversible capacity, providing valuable guidance for rational precursor selection and process optimization during industrial manufacturing [
123]. Optimization of biomass precursor composition provides another effective route for tailoring hard carbon microstructure. Carefully controlled precursor engineering simultaneously improves initial coulombic efficiency, reversible capacity, and long-term cycling stability. The successful validation of pouch cells further demonstrates the practical viability of waste wood-derived hard carbon for commercial sodium-ion battery applications [
124].
4.4 Research frontiers: fast-charging hard carbon
Chinese researchers have recently reported breakthroughs in addressing the intrinsic limitations of hard carbon for fast-charging applications. The material's disordered internal structure while beneficial for sodium storage capacity impedes rapid electron transport and creates tortuous sodium diffusion pathways, resulting in poor rate performance. Scientists have developed approaches to engineer hard carbon pore architecture and carbon layer alignment, achieving significantly improved rate capability while maintaining high specific capacity. Engineering the pore architecture of hard carbon has emerged as an effective strategy for improving fast-charging performance. Controlled gas-etching treatments generate abundant closed pores while optimizing internal carbon morphology, enabling rapid sodium transport without sacrificing reversible capacity or initial coulombic efficiency. These advances demonstrate that rational pore engineering can overcome one of the principal limitations of hard carbon anodes for high-rate sodium-ion batteries [
125]. Precise molecular-level structural regulation through pre-oxidation and cross-linking has also proven effective for producing hard carbon with abundant closed pores and enhanced structural stability. These modifications simultaneously improve reversible capacity, initial coulombic efficiency, rate capability, and cycling stability while providing further insight into the sequential sodium-storage mechanism within hard carbon [
126]. Optimization of carbonization temperature provides another effective route for regulating the pore structure of biomass-derived hard carbon. Proper thermal treatment simultaneously enhances reversible capacity, initial coulombic efficiency, fast-charging capability, long-term cycling stability, and low-temperature performance, demonstrating the versatility of microstructural engineering for practical sodium-ion battery applications [
127].
Table 3 compares the electrochemical performance of representative hard carbon anodes derived from a wide range of biomass, petroleum, coal, and industrial carbon precursors. Collectively, these studies demonstrate that precursor selection and microstructural engineering strongly influence reversible capacity, initial coulombic efficiency, rate capability, and long-term cycling stability. The comparison also highlights the continuing trade-offs between high capacity, fast charging, and manufacturing practicality that currently define commercial hard carbon development.
5 Industrialization in 2026: the major players
The year 2026 marks a pivotal moment in the commercialization of sodium-ion batteries, with major manufacturers transitioning from pilot-scale production to gigawatt-hour manufacturing capacity. This section examines the industrialization strategies of the leading players CATL, BYD, Gotion High-Tech, EVE Energy, and Sunwoda who have collectively announced mass production by the fourth quarter of 2026. The analysis covers each company's technological approach, manufacturing capacity, product specifications, and strategic positioning, drawing on independent academic validation of their claims. The section concludes with an overview of the broader SIB ecosystem, encompassing over 200 companies across the value chain, and summarizes announced capacity commitments that support projections of exceeding 500 GWh by 2030.
5.1 CATL: the technological leader
CATL has emerged as the leading industrial developer of sodium-ion batteries, combining advanced cell performance with large-scale manufacturing commitments and early commercial deployment. At its April 2026 “Super Tech Day”, the company announced that its second-generation Naxtra sodium-ion battery would enter scaled production in the fourth quarter of 2026 for use in battery-swapping systems, passenger vehicles, commercial vehicles, and stationary energy storage. CATL reports a cell-level energy density of 175 Wh kg
-1, increased from approximately 160 Wh kg
-1 for its first-generation platform, together with 5C fast-charging capability, a projected cycle life of up to 10, 000 cycles, and more than 90% capacity retention at −40 °C. The platform has also reportedly passed severe mechanical-abuse tests, including drilling and cutting, without fire or explosion. Commercialization is supported by both vehicle integration and substantial manufacturing investment. Naxtra cells have been announced for vehicles produced by GAC Aion, Changan Oshan, Jiefang, and Jianghuai Logistics, with additional models from Geely, Chery, and FAW expected to follow. CATL has also committed approximately RMB 5 billion (USD 0.7 billion) to a dedicated 40 GWh sodium-ion battery production line at its Fuding facility, complementing its broader battery manufacturing infrastructure. A three-year, 60 GWh supply agreement with Hyper strong further provides anchor demand from the stationary energy-storage sector. Collectively, these developments indicate that CATL’s sodium-ion strategy has progressed beyond pilot-scale demonstration toward coordinated manufacturing expansion, product integration, and downstream market formation [
143]. System-level analyses provide useful context for evaluating the practical implications of CATL’s announced performance. A plug-in hybrid vehicle architecture incorporating a 30 kWh sodium-ion battery showed that a lower-capacity sodium-ion pack could reduce vehicle mass, manufacturing cost, and annual energy consumption relative to a substantially larger nickel-manganese-cobalt battery pack. The analysis also emphasized the value of sodium-ion chemistry under cold-climate conditions, where high capacity and power retention may partly compensate for its lower nominal energy density relative to high-energy lithium-ion systems [
144]. These findings support CATL’s positioning of Naxtra for moderate-range mobility, commercial vehicles, and applications in which low-temperature reliability, safety, and cost are more important than maximizing driving range. However, because several performance values used in such system-level assessments originate from manufacturer specifications, they should be interpreted as scenario-based evaluations rather than fully independent validation of long-term commercial-cell performance.
Pilot-scale manufacturing studies provide stronger experimental evidence for the compatibility of sodium-ion technology with established battery-production infrastructure. Aqueous processing of Prussian White cathodes and hard carbon anodes has enabled the production of approximately 1 Ah pouch cells with a practical specific energy of about 120 Wh kg
-1 [
145]. Although this value remains below CATL’s announced 175 Wh kg
-1 cell-level performance, the difference highlights the importance of electrode loading, cell balancing, electrolyte quantity, inactive material fractions, and production yield during the transition from laboratory electrodes to optimized commercial cells. More importantly, successful operation across slurry preparation, kneading, coating, drying, and calendaring demonstrates that sodium-ion electrodes can be manufactured using processes closely related to those employed in lithium-ion production. As summarized in
Figure 10, the pilot-line workflow therefore supports the technical feasibility of adapting mature roll-to-roll manufacturing infrastructure for sodium-ion batteries while also illustrating the process optimization required before announced gigawatt-hour capacities can be achieved with consistent product quality. Overall, CATL’s principal advantage lies not only in the reported performance of the Naxtra platform but also in its ability to integrate materials development, cell engineering, manufacturing scale-up, vehicle deployment, and energy-storage demand. Nevertheless, announced specifications such as 10, 000-cycle life, extreme-temperature retention, and large-scale production readiness will require continued verification under standardized testing and long-duration field operation. CATL’s progress therefore represents the strongest current indication of sodium-ion industrial maturity, while the distinction between manufacturer-reported targets, pilot-line demonstrations, and independently verified commercial performance should remain clear.
High-energy layered oxide sodium-ion cells offer attractive energy density and rate capability, but their safety performance remains strongly dependent on cathode chemistry and thermal-management design. Comparative abuse testing of commercial NFM layered oxide and NaFePO
4 (NFP) polyanionic cells showed substantially more severe thermal runaway for the NFM chemistry, including higher peak temperature, a faster temperature rise, and sustained jet-flame behavior. Fluorinated liquid immersion cooling markedly reduced these hazards by lowering the peak temperature by 53.4%, shortening the jet-flame duration from 11 to 2 s, and decreasing the comprehensive fire-risk index from 98.1% to 63.1% [
146]. These findings indicate that the commercialization of high-energy layered oxide platforms, including CATL’s Naxtra technology, will require robust pack-level thermal management rather than reliance on intrinsic cell chemistry alone. Accordingly, the results support the feasibility of mitigating thermal runaway risks, but they should not be interpreted as direct confirmation of manufacturer-reported safety claims.
The scalability of layered oxide cathodes also depends on controlling phase evolution and particle architecture during synthesis. Li-substituted P-type materials demonstrate that electrochemical performance is governed less by morphology alone than by the combined effects of surface area, phase stability, and oxygen-redox behavior. Among the evaluated structures, P2-polycrystalline cathodes retained approximately 90% of their capacity after 150 cycles and sustained rate capability up to 10C, illustrating the potential of appropriately engineered layered oxides for fast-charging applications [
147]. The observed P3-to-P2 transformation, in which the P2 phase develops inward from the particle surface, further shows that synthesis can generate beneficial core-shell-like architectures without complex post-processing. These results provide a mechanistic basis for improving the rate capability and structural durability required for industrial sodium-ion cathodes, although direct validation in CATL’s proprietary Naxtra cells remains unavailable.
5.2 BYD: deep integration of LFP and sodium
BYD has adopted a commercialization strategy that positions sodium-ion batteries as a complement to, rather than a replacement for, its well-established LFP technology. Consistent with this strategy, He Long, Senior Vice President of BYD and chief executive officer of FinDreams Battery, has described sodium-ion technology as "an extension of BYD's LFP strategy, " emphasizing application-specific deployment rather than direct competition between battery chemistries. To support this transition, BYD began construction of its first dedicated sodium-ion battery manufacturing facility in Xuzhou, Jiangsu Province, in 2024 with an initial production capacity of 30 GWh and an investment of approximately RMB 10 billion (USD 1.4 billion). The company has also established a sodium-ion Blade Battery production line at its Shaoxing facility and reports that its third-generation platform has overcome key limitations associated with high-temperature operation and sodium plating while achieving a projected cycle life exceeding 10, 000 cycles [
148,
149]. Recent investigations support BYD's strategy of leveraging its mature LFP manufacturing ecosystem to accelerate sodium-ion commercialization. Characterization of commercial 18650 sodium-ion cells demonstrate that layered oxide cathodes combined with hard carbon anodes provide competitive cost, high-rate capability, and stable cycling, confirming that sodium-ion batteries are particularly attractive for high-power and cost-sensitive applications rather than maximum-energy-density markets [
150]. More broadly, engineering analyses indicate that sodium-ion batteries can exploit manufacturing concepts originally developed for LFP systems, allowing existing production infrastructure and cell designs to be adapted with relatively limited process modification. This compatibility substantially lowers manufacturing barriers while reinforcing sodium-ion batteries as a practical complement within diversified battery portfolios rather than an independent production pathway [
151].
From a strategic perspective, sodium-ion technology also addresses growing concerns regarding critical-material dependence and supply-chain resilience. Techno-economic and policy analyses consistently identify sodium-ion batteries as an effective means of reducing reliance on lithium, cobalt, and nickel while improving long-term resource security in rapidly expanding electric vehicle markets [
152]. At the application level, current sodium-ion performance is considered sufficient for stationary energy storage and moderate-range electric vehicles, where advantages in safety, low-temperature operation, and manufacturing cost can outweigh the lower energy density relative to advanced lithium-ion chemistries [
153].
5.3 Gotion high-tech: anode-free innovation
Gotion High-Tech introduced its "Na-Chen" (Sodium Morning) battery series at its 2026 Global Technology Conference, comprising an energy-storage version (180 Ah), a power version (162 Wh kg-1), and a high-energy version (261 Wh kg-1), the latter representing approximately a 60% increase in energy density over conventional sodium-ion batteries. This improvement is achieved through an anode-free architecture employing multi-stage pre-sodiation technology, which eliminates the hard carbon anode and allocates a greater proportion of the cell volume to active cathode materials. From a manufacturing perspective, this approach offers the potential to reduce material consumption and simplify cell design while increasing gravimetric energy density. Despite these advantages, the commercial readiness of anode-free sodium batteries remains uncertain. As discussed in Section 4.3, repeated sodium plating and stripping continue to present major engineering challenges, including non-uniform sodium deposition, unstable solid-electrolyte interphase (SEI) formation, irreversible sodium loss ("dead Na"), rapid capacity decay, reduced volumetric efficiency, and the risk of internal short circuits arising from dendrite growth. Although Gotion has announced plans for GWh-scale production beginning in Q4 2026, long-term cycle-life data and independent validation of the high-energy platform have not yet been disclosed. Consequently, the announced commercialization timeline should be regarded as a significant industrial milestone rather than confirmation that the remaining technical barriers to large-scale deployment have been fully resolved.
Recent studies nevertheless demonstrate encouraging progress toward overcoming these limitations. Sodium-compensation strategies using low-cost organic sodium reservoirs substantially improve sodium utilization and cycling stability, supporting the feasibility of pre-sodiation approaches for anode-free cells [
154]. Mechanochemical interfacial engineering has enabled scalable fabrication of ultrathin sodium foils that function as efficient pre-sodiation agents while improving manufacturing processability [
155]. Advances in electrolyte and interface engineering, including dual-salt electrolytes combined with mesoporous carbon hosts, have further improved sodium deposition uniformity by stabilizing the SEI, suppressing dendrite growth, and reducing irreversible sodium loss during cycling [
156]. In parallel, low-defect carbon hosts have demonstrated that zero-excess sodium batteries can achieve high initial Coulombic efficiency and competitive energy density without artificial pre-sodiation, providing an alternative pathway toward practical anode-free battery architectures [
157]. These studies demonstrate that anode-free sodium batteries possess considerable long-term potential for increasing energy density and reducing manufacturing costs. However, current research remains focused on addressing fundamental challenges associated with sodium deposition reversibility, long-term cycling stability, volumetric efficiency, and operational safety. Consequently, widespread commercial adoption will depend on continued advances in interface engineering, electrolyte design, and sodium management before large-scale industrial deployment can be considered fully mature.
5.4 EVE energy, Sunwoda, and emerging players
EVE Energy has moved from technology validation to the commercialization phase, with its independently designed NF155L SIB product ready for mass production. The company expects batch deliveries in 2026 and aims to establish 2 GWh of SIB capacity by 2027. Sunwoda has finalized its sodium-ion platform products and is prepared for mass production, with energy storage sector projects currently advancing. Beyond these major players, the SIB ecosystem has expanded to include over 200 companies across the value chain, encompassing everything from precursor materials to cell manufacturing to system integration. Notable participants include Tianneng, Highpower/Sinolytics, DFD New Energy, Veken Technology, and Transimage Technology [
158].
Among emerging players, Natron Energy has distinguished itself by commercializing sodium-ion batteries based on PBA. Hartmann et al. (2023) investigated the moisture sensitivity of Prussian White (Na
1.
8Mn
0.
8Fe
0.
2[Fe(CN)
6]
0.
9) a key challenge for this chemistry demonstrating that while fully sodiated material gains nearly 20% mass from interstitial water absorption, vacuum drying at 150°C effectively removes interstitial water and restores the rhombohedral crystal structure. Critically, aqueous electrode processing was shown to be feasible with carboxymethyl cellulose/sodium polyacrylate binders, achieving comparable performance to N-methyl-2-pyrrolidone-based electrodes. This work validates the manufacturing viability of Natron Energy's PBA-based SIB technology, which has demonstrated exceptional cycle life (up to 40, 000 cycles) for stationary storage applications [
159]. Although interstitial water control, vacancy defects, and structural stability remain important manufacturing challenges for PBA cathodes, these issues primarily affect manufacturing optimization and production yield rather than preventing commercialization. Instead, current industrial deployment reflects both application-specific requirements and commercial strategy. Major Chinese manufacturers have largely prioritized layered oxide cathodes because of their higher energy density and greater compatibility with existing lithium-ion manufacturing infrastructure, making them more suitable for electric mobility and mainstream energy storage applications. In contrast, Natron Energy has successfully commercialized PBA-based sodium-ion batteries by targeting stationary storage applications, where exceptional power capability, long cycle life, and intrinsic safety outweigh energy-density limitations. Consequently, current industrial development reflects both material-specific manufacturing considerations and application-specific commercial strategies rather than a universal manufacturing limitation of PBA materials. Commercial benchmarking studies indicate that current sodium-ion batteries have already achieved performance levels suitable for practical applications while also revealing the remaining technological challenges. Comparative evaluation of commercial 18650-format sodium-ion cells employing layered oxide cathodes and hard carbon anodes demonstrated lower cell weight and simpler electrode architectures than comparable lithium-ion batteries. However, these cells exhibited greater temperature-dependent capacity loss and higher internal impedance because of the intrinsically slower sodium-ion diffusion kinetics. Despite these limitations, manufacturing-related inhomogeneities such as asymmetric electrode structures were found to have only a minor influence on electrochemical performance, suggesting that further improvements in cell engineering and process optimization can enhance commercial competitiveness [
160]. The long-term sustainability of sodium-ion battery commercialization will also depend on establishing efficient recycling and circular economy strategies alongside manufacturing expansion. Although recent assessments have focused primarily on lithium-ion batteries, many of the identified logistical and economic challenges are directly applicable to emerging sodium-ion industries. Transportation costs, limited recycling throughput, and fragmented infrastructure remain significant barriers to economically viable battery recycling. Consequently, decentralized spoke-and-hub recycling networks have been proposed to reduce transportation distances, improve processing efficiency, and facilitate closed-loop recovery of valuable materials
(Figure 11). Incorporating recyclability into battery design and establishing supply-chain partnerships during the early stages of commercialization will therefore be important for ensuring the long-term sustainability of large-scale sodium-ion battery deployment [
161].
The industrialization status and key performance metrics of major sodium-ion battery manufacturers are summarized in
Table 4. As shown in
Table 4, CATL leads with its Naxtra technology achieving 175 Wh kg
-1, 5C fast charging, and a 10, 000-cycle life, supported by a 40 GWh dedicated production line and a landmark 60 GWh order from Hyperstrong. BYD follows with its sodium-ion blade cell platform built on a 30 GWh facility in Xuzhou, targeting micro-cars and energy storage applications. Gotion's "Na-Chen" anode-free architecture achieves 261 Wh kg
-1 in its high-energy version, representing a 60% improvement over conventional SIB energy density. Emerging players such as EVE Energy and Sunwoda are entering the commercialization phase, while Natron Energy has distinguished itself with PBA-based SIBs offering up to 40, 000 cycles for stationary storage applications. Collectively, these announcements support industry projections that global SIB manufacturing capacity could exceed 500 GWh by 2030.
6 Outlook and strategic implications
6.1 Application landscape: where SIBs will first compete
The commercial success of SIBs will depend not on replacing lithium-ion batteries across all markets but on targeting applications where their combination of low cost, long cycle life, intrinsic safety, and resource abundance provides a clear competitive advantage. Current techno-economic analyses consistently indicate that SIB deployment will initially concentrate in stationary energy storage, low-speed mobility, and auxiliary power systems, where moderate energy density is offset by lower manufacturing costs and superior operational reliability. Stationary energy storage is expected to remain the largest near-term market, already accounting for approximately half of current SIB demand. Unlike electric vehicles, grid-scale storage prioritizes lifetime cost, safety, and durability over gravimetric energy density. Recent studies demonstrate that sodium-ion full cells can achieve cycle lives exceeding 10, 000 cycles while maintaining stable performance at high charge-discharge rates, enabling a lower levelized cost of energy storage for daily cycling applications [
165]. System-level demonstrations integrating sodium-ion batteries with photovoltaic microgrids further confirm their suitability for utility-scale, commercial, and residential energy storage, while excellent low-temperature performance broadens their applicability in regions exposed to severe winter conditions. Commercial pouch cells retaining usable energy at temperatures as low as −50 °C further highlight the potential of SIBs for emergency backup power and distributed energy-storage systems operating under harsh environmental conditions [
166]. Beyond stationary storage, SIBs are well positioned for cost-sensitive transportation markets in which affordability, durability, and cold-weather performance are more important than maximum driving range. Electric bicycles, electric motorcycles, neighborhood electric vehicles, and last-mile delivery vehicles represent attractive early deployment opportunities because their operating requirements align closely with the performance envelope of current sodium-ion technology. Iron-based phosphate pouch cells with practical energy densities around 110 Wh kg
-1, excellent capacity retention after thousands of cycles, and stable operation from −40 °C to 60 °C demonstrate that present-day SIB technology already satisfies the performance requirements of these mobility sectors [
167]. Consequently, sodium-ion batteries are more likely to complement rather than compete directly with high-energy lithium-ion batteries in mainstream passenger electric vehicles.
Automotive start-stop systems represent another promising application in which sodium-ion batteries could gradually replace conventional lead-acid technology. Their excellent low-temperature power capability, long cycle life, and reduced dependence on critical minerals make them attractive for auxiliary automotive power, while experimental evaluations have confirmed their ability to satisfy cold-start requirements under demanding operating conditions [
168]. Market analyses likewise identify start-stop systems as an important contributor to future sodium-ion demand because they require high power rather than high energy density. Emerging opportunities are also beginning to appear in sectors where safety and service life are particularly important. AI data-center backup systems can benefit from the excellent thermal stability and long operational lifetime of sodium-ion batteries, while marine energy-storage systems may similarly exploit their reduced thermal-runaway risk relative to conventional lithium-ion chemistries. Nevertheless, despite these expanding opportunities, current evidence indicates that SIBs are unlikely to penetrate the premium long-range electric vehicle market in the near future. Benchmarking studies consistently show that commercial sodium-ion cells remain significantly below state-of-the-art lithium-ion batteries in both gravimetric and, especially, volumetric energy density, with volumetric deficits of approximately 17-49% relative to contemporary LFP cells [
169]. Accordingly, the most realistic commercialization pathway is one of market complementarity, in which sodium-ion batteries occupy applications where safety, cost, supply-chain resilience, and operational durability outweigh the need for maximum energy density.
6.2 Remaining challenges and critical risks
Despite remarkable progress, several challenges threaten to constrain SIB adoption. The energy density gap to LFP translates directly into heavier, bulkier battery packs, impeding widespread adoption in passenger vehicles where mass and interior space are at a premium. Comprehensive modeling of commercially pursued SIB cell chemistries confirms that current SIB cells show notably lower energy content compared to the LFP benchmark, particularly in terms of volumetric energy density (Δ = 17-49%). However, this gap could be narrowed and even closed for specific SIB cell chemistries through optimization of hard carbon, representing a near-future scenario [
169]. The path to closing this gap runs through improved cathode formulations, advanced hard carbon anodes with optimized pore architecture, and cell engineering improvements. Anode-free designs such as Gotion's Na-Chen (261 Wh/kg) demonstrate theoretical potential, though practical cycle life remains unproven. Zhao et al. (2023) further noted that SIB recycling faces a higher economic barrier compared to LIB recycling because SIBs lack high-valued metals such as lithium and cobalt, diminishing profitability and potentially hindering industrial recycling [
170]. The comparison of sodium-ion batteries with major commercial battery technologies are presented in
Table 5.
As summarized in
Table 5, sodium-ion batteries occupy an intermediate position between conventional lead-acid batteries and lithium-ion technologies. Although their gravimetric and volumetric energy densities remain below those of state-of-the-art NMC and, to a lesser extent, LFP batteries, SIBs provide a compelling combination of intrinsic safety, excellent low-temperature operation, long cycle life, reduced dependence on critical minerals, and competitive manufacturing costs. These characteristics position sodium-ion batteries as a complementary technology for stationary energy storage, low-speed electric mobility, and other cost-sensitive applications where safety, durability, and resource sustainability outweigh the need for maximum energy density.
Hard carbon consistency remains a formidable challenge, as biomass-derived hard carbon suffers from inherent batch-to-batch variability due to natural variation in precursor materials, manifesting as cell-to-cell performance variation. Research has identified that optimizing the microstructure of hard carbon materials including controlling pore size distribution, surface area, and crystallinity is crucial for sodium ion battery performance. Standardized testing protocols are essential to identify defects and ensure batch-to-batch consistency, which is critical for maintaining performance standards in sodium-ion battery production. The industry is pursuing advanced pre-processing techniques and a shift toward synthetic precursors (petroleum or coal pitch), though these introduce higher energy input and greater environmental footprint. The "hard carbon gas evolution problem" the tendency of disordered carbon structures to generate gas during formation cycling has been overcome by CATL through advanced drying protocols and electrolyte additive engineering, but smaller manufacturers may struggle to achieve comparable performance.
The single greatest exogenous risk is a sustained decline in lithium carbonate prices. Techno-economic modeling comparing projected sodium-ion and lithium-ion price trends across over 6, 000 scenarios reveal that sodium-ion competitiveness timelines are highly sensitive to movements in critical minerals supply chains namely that of lithium, graphite, and nickel. The modeled outcomes suggest that being price advantageous against low-cost lithium-ion variants in the near term is challenging, and increasing sodium-ion energy densities to decrease materials intensity is among the most impactful ways to improve competitiveness. If lithium returns to levels well below current prices, the cost advantage of sodium over lithium would erode significantly. Technical route uncertainty also looms large, as the industrial consensus on preferred materials and manufacturing processes is still evolving. The record level of patent filings 7, 032 in 2024 alone indicates the technical landscape remains highly contested [
171]. Finally, while leading SIBs from CATL and BYD claim 10, 000-cycle life, third-party validation remains limited. Early-generation SIBs typically achieved only 3, 000-5, 000 cycles, and the next 12-24 months will be critical for building the operating history required for storage projects with 20-year design lives.
6.3 Implications for energy manufacturing
The rise of sodium-ion batteries portends a fundamental shift in battery manufacturing strategy. Rather than a single incumbent technology, the industry is moving toward a diversified portfolio in which different cell chemistries are deployed according to their comparative advantages across cost, energy density, and application requirements. For battery manufacturers, this diversification reduces exposure to raw material price volatility. Companies that can produce both lithium-ion and sodium-ion cells on flexible manufacturing lines will be better positioned to respond to lithium price movements than those locked into a single chemistry. The capital cost of flexible lines is substantial, but for tier-one manufacturers such as CATL and BYD, this flexibility is increasingly viewed as a strategic necessity.
Sodium-ion batteries challenge the prevailing policy framework that has focused nearly exclusively on securing lithium supplies. If SIBs succeed in capturing 10-20% of the energy storage market, lithium demand from the storage sector could be reduced by an equivalent proportion, easing pressure on lithium supply chains. For countries that lack domestic lithium resources but possess abundant salt deposits India, Brazil, the United States, and many others SIBs offer a pathway to battery independence that bypasses the geopolitical complications of lithium procurement, potentially reshaping the global distribution of battery production capacity.
SIB manufacturing shares substantial commonality with lithium-ion production, enabling reuse of existing equipment with modest modifications. Sodium-ion batteries are considered a commercially viable option because of the processing similarity with lithium-ion batteries. However, sodium-based chemistries create unique equipment requirements: hard carbon anodes require specialized milling, coating, and drying equipment; aluminum foil processing for both electrodes demands tighter control of foil thickness and surface finish; and formation protocols must be adapted to manage gas evolution characteristics. Equipment manufacturers are rapidly developing SIB-specific tools, with the global equipment market projected to reach $2-3 billion by 2030. The transition also requires new technical expertise across materials science, process engineering, and quality control, with a significant skills gap persisting despite specialized courses emerging in Chinese universities.
SIBs offer significant environmental advantages, including elimination of cobalt (removing a major source of supply chain environmental and human rights concerns), dramatically lower environmental impact from sodium extraction compared to hard-rock lithium mining, and reduced embodied carbon from aluminum (rather than copper) current collectors. Life cycle assessment studies show that among evaluated SIB cell chemistries, four demonstrate carbon footprints that are highly competitive with the LFP benchmark (Δ = 1-8%), despite exhibiting lower energy densities, primarily due to the substantially lower carbon footprint of hard carbon (3.2 kg CO2-eq. kg-1) compared to synthetic graphite (25.1 kg CO2-eq. kg-1). However, hard carbon production is energy-intensive, and if powered by coal-fired electricity still dominant in many industrial regions of China could offset some of these advantages. The disposal and recycling of SIBs is not yet well understood, though the absence of toxic heavy metals in most SIB chemistries simplifies end-of-life management relative to lead-acid or NMC cells.
7. Conclusion
Sodium-ion batteries have progressed from an emerging research topic to a commercially viable battery technology with the potential to complement, rather than replace, lithium-ion batteries across the global energy storage landscape. This transition has been enabled by simultaneous advances in electrode materials, cell engineering, manufacturing technologies, and industrial investment, supported by the strategic need to diversify battery supply chains and reduce dependence on critical minerals. The convergence of layered oxide cathodes for mobility applications and polyanionic compounds for stationary energy storage, together with continued improvements in hard carbon anodes, has established a practical technological foundation for large-scale commercialization. A defining advantage of sodium-ion technology is its compatibility with existing lithium-ion manufacturing infrastructure. Unlike many next-generation battery chemistries that require entirely new production ecosystems, sodium-ion batteries can leverage mature electrode processing, roll-to-roll manufacturing, and cell assembly technologies with relatively limited process modifications. This compatibility substantially reduces capital investment requirements while accelerating industrial deployment. The large-scale manufacturing commitments announced by leading companies, including CATL, BYD, Gotion High-Tech, and EVE Energy, demonstrate that commercialization is no longer driven solely by laboratory-scale innovation but increasingly by manufacturing readiness, supply-chain integration, and market demand.
The comparative analysis presented in this review demonstrates that sodium-ion batteries occupy a distinct position within the evolving battery landscape. Although their gravimetric and volumetric energy densities remain below those of state-of-the-art lithium-ion batteries, particularly nickel-rich chemistries, they offer compelling advantages in raw material abundance, intrinsic safety, low-temperature performance, manufacturing cost, and reduced dependence on geopolitically constrained critical minerals. Consequently, the earliest large-scale deployment of sodium-ion batteries is expected in stationary energy storage, low-speed electric mobility, start-stop systems, and other cost-sensitive applications where long cycle life, operational safety, and affordability outweigh the need for maximum energy density. Despite this progress, several important challenges remain before sodium-ion batteries achieve widespread commercialization. Increasing energy density through optimized cathode compositions and hard carbon engineering remains the highest technical priority. Additional efforts are required to improve hard carbon manufacturing consistency, reduce gas evolution during initial cycling, establish economically sustainable recycling pathways, and generate long-term field data that independently validate the performance and durability claimed by commercial manufacturers. Furthermore, future market competitiveness will continue to depend on fluctuations in lithium and other critical mineral prices, manufacturing scale, and continued improvements in production efficiency. Overall, sodium-ion batteries should be viewed as an integral component of a diversified battery ecosystem rather than a universal replacement for lithium-ion technology. Their greatest commercial impact will arise from application-specific deployment in markets where cost, safety, sustainability, and supply-chain resilience are prioritized over maximum energy density. Continued collaboration between academia, industry, and policymakers will be essential to accelerate materials innovation, manufacturing optimization, standardization, and recycling infrastructure. As these technological and industrial developments continue to mature, sodium-ion batteries are well positioned to become a key pillar of future sustainable energy storage and electrification, supporting the global transition toward resilient, low-carbon energy systems.
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