Sodium-ion battery
A sodium-ion battery (NIB, SIB, or Na-ion battery) is a rechargeable battery that uses sodium ions (Na+) as charge carriers. In some cases, its working principle and cell construction are similar to those of lithium-ion battery (LIB) types, by replacing lithium with sodium as the intercalating ion. Sodium belongs to the same group in the periodic table as lithium and thus has similar chemical properties. However, designs such as aqueous batteries are quite different from LIBs.
Sodium-ion battery development took place in the 1970s and early 1980s. However, by the 1990s, lithium-ion batteries had demonstrated more commercial promise, causing interest in sodium-ion batteries to decline. In the early 2010s, sodium-ion batteries experienced a resurgence, driven largely by the increasing cost of lithium-ion battery raw materials. Also, the number of patent families reached the number of non-patent publication after ca. 2020, which usually signify the fact that the technology reached the commercialization stage.
SIB cells consist of a cathode based on a sodium-based material, an anode (not necessarily a sodium-based material) and a liquid electrolyte containing dissociated sodium salts in polar protic or aprotic solvents. During charging, sodium ions move from the cathode to the anode while electrons travel through the external circuit. During discharge, the reverse process occurs.
Due to the physical and electrochemical properties of sodium, SIBs require different materials from those used for LIBs.
Anodes
SIBs can use hard carbon, a disordered carbon material consisting of a non-graphitizable, non-crystalline and amorphous carbon. Hard carbon's ability to absorb sodium was discovered in 2000. This anode was shown to deliver 300 mAh/g with a sloping potential profile above ~0.15 V vs Na/Na+. It accounts for roughly half of the capacity and a flat potential profile (a potential plateau) below ~0.15 V vs Na/Na+. Such capacities are comparable to 300–360 mAh/g of graphite anodes in lithium-ion batteries. The first sodium-ion cell using hard carbon was demonstrated in 2003 and showed a 3.7 V average voltage during discharge. Hard carbon was the preferred choice of Faradion due to its excellent combination of capacity, (lower) working potentials, and cycling stability. Notably, nitrogen-doped hard carbons display even larger specific capacity of 520 mAh/g at 20 mA/g with stability over 1000 cycles.
Cathodes
SIBs can use more affordable materials in their construction, such as generally cheaper cathode materials like manganese and iron, and the use of aluminium collectors instead of copper ones in LIBs. Many layered transition metal oxides can reversibly intercalate sodium ions upon reduction. This is conventionally understood to occur through a change in oxidation state of the transition metal cations in the oxide lattice. However in recent years, the understanding of sodium insertion and removal in these lattices has shifted, and it is now appreciated that anionic redox plays a determining role in sodium-ion battery cathodes, particularly those containing Manganese, which does not change its oxidation state during cycling. Sodic transition metal oxides typically have a higher tap density and a lower electronic resistivity, than other cathode materials (such as phosphates). Due to a larger size of the Na+ ion (116 pm) compared to Li+ ion (90 pm), cation mixing between Na+ and first row transition metal ions (which is common in the case of Li+) usually does not occur. Thus, low-cost iron and manganese oxides can be used for Na-ion batteries, whereas Li-ion batteries require the use of more expensive cobalt and nickel oxides. The drawback of the larger size of Na+ ion is its slower intercalation kinetics compared to Li+ ion and the presence of multiple intercalation stages with different voltages and kinetic rates.
Electrolytes
Sodium-ion batteries can use aqueous and non-aqueous electrolytes. The limited electrochemical stability window of water results in lower voltages and limited energy densities. Non-aqueous carbonate ester polar aprotic solvents extend the voltage range. These include ethylene carbonate, dimethyl carbonate, diethyl carbonate, and propylene carbonate. The most widely used salts in non-aqueous electrolytes are NaClO4 and sodium hexafluorophosphate (NaPF6) dissolved in a mixture of these solvents. It is a well-established fact that these carbonate-based electrolytes are flammable, which pose safety concerns in large-scale applications. A type of glyme-based electrolyte, with sodium tetrafluoroborate as the salt is demonstrated to be non-flammable. In addition, NaTFSI (TFSI = bis(trifluoromethane)sulfonimide) and NaFSI (FSI = bis(fluorosulfonyl)imide, NaDFOB (DFOB = difluoro(oxalato)borate) and NaBOB (bis(oxalato)borate) anions have emerged lately as new interesting salts. Electrolyte additives can be used as well to improve the performance metrics.
Aqueous sodium-ion batteries
Aqueous sodium-ion batteries (ASIBs) have gained significant attention in energy storage and conversion because they offer high safety, low cost, and improved environmental compatibility. Cathodes represent the primary constraint on ASIB performance. Intercalation-type materials offer only a finite number of Na+ storage sites, which limits the extent to which their specific capacity can be improved. Sodium transition-metal oxides (NaxMO2) are among the most extensively studied ASIB cathodes due to their open structures, electrochemical stability, high working voltage, and lower cost compared with lithium analogues (75). Their properties can be tuned by varying Na content, yielding layered oxides (x < 0.5) and tunnel oxides (x > 0.5). Layered P2- and O3-type oxides offer high capacities and fast Na+ diffusion (76), illustrated by P2-Na2⁄3Ni1⁄3Mn2⁄3O2 delivering 157 mAh/g in Na2SO4 electrolyte (70) and P2-Na2⁄3Ni1⁄4Mn3⁄4O2 achieving a 1.2 V full-cell voltage when paired with NTP/graphite in a hybrid Na2SO4/Li2SO4 electrolyte. However, P2 phases undergo P2→O2 transitions at low Na content, while O3 phases such as NaMnO2 suffer from air/moisture instability; heteroatom substitution, such as Cu/Ti-doping in NaNi0.45Mn0.5O2, significantly improves air stability and cycling performance. Tunnel oxides like Na0.44MnO2 enable rapid Na+ transport and excellent cycling, achieving stable capacities in Na2SO4 and NaOH electrolytes, and their performance can be enhanced through Ti substitution and Na-rich compositions or even extended to potassium-based analogues such as K0.27MnO2. Prussian blue analogs (PBAs), with their open 3D framework, fast kinetics, and facile synthesis, offer capacities up to ~80 mAh/g, and some two-electron PBAs reach theoretical capacities of 170 mAh/g; reducing defects and adding Co2+ can greatly improve stability and capacity retention. Polyanionic compounds—including phosphates, fluorophosphates, and NASICON-type materials—provide stable 3D host structures and high voltage operation, though they often face interfacial resistance and transition-metal dissolution issues. Improvements through carbon coating and metal substitution have enabled materials like NaFePO4 to reach high reversible capacities and favorable high-temperature performance, while fluorophosphates such as Na3V2(PO4)2F3-SWCNT deliver higher working voltages. Recent advances in mixed phosphate–pyrophosphate frameworks, such as Na4Fe3(PO4)2P2O7, have demonstrated high power density, long cycle life, and even low-temperature operation. Graphite is generally not used as an anode in ASIBs, as the NaxC compounds it forms are thermodynamically unstable. This instability leads to low reversible capacity and an unfavorable reaction potential. Activated carbon (AC) is a structurally simple and easily manufactured carbon material that can be paired with suitable cathodes to form asymmetric hybrid capacitor–battery systems. For example, a Na4Mn9O18//Na2SO4/AC supercapacitor achieved an energy density of 34.8 Wh/kg and exhibited excellent cycling stability, retaining 84% of its capacity after 4,000 cycles at 18 C. In addition, other carbon-based materials—such as carbon microbeads and carbon fibers—have also been explored as potential anodes for sodium storage. However, many carbon materials still face challenges including low initial Coulombic efficiency and sluggish Na+ intercalation kinetics. Nanoengineering offers effective solutions to these limitations by shortening Na+ and electron diffusion pathways, creating reticular architectures that improve mechanical robustness and buffer volume changes during cycling, and increasing surface area and active sites. These structural advantages make nanoscale engineering an essential strategy for enhancing the electrochemical performance of carbon-based anodes in ASIBs.
Sodium-ion batteries have several advantages over competing battery technologies. Compared to lithium-ion batteries, sodium-ion batteries have somewhat lower cost, better safety characteristics (for the aqueous versions), and similar power delivery characteristics, but also a lower energy density (especially the aqueous versions). Round-trip efficiency is mostly equal, but is lower for sodium-ion at a low state of charge (SOC). The table[needs update] below compares how NIBs in general fare against the three established rechargeable battery technologies in the market currently: the nickel-manganese-cobalt (NMC) lithium-ion battery, the lithium iron phosphate battery (LFP) and the rechargeable lead–acid battery.
Imagem: Vladimir022009 · BY-SA · Openverse
University of Chicago/UC San Diego
In July 2024, the University of Chicago and UC San Diego developed an anode-free sodium solid-state battery that they claimed was cheaper, safer, fast charging, and high capacity.
Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR)
A research team at the Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), an autonomous institute of the Department of Science and Technology (DST) has developed a super-fast charging sodium-ion battery (SIB) based on a NASICON-type cathode and anode material, that can charge up to 80% in just six minutes and last over 3000 charge cycles.
Companies around the world develop commercially viable sodium-ion batteries, mainly in China. A 2-hour 5 MW/10 MWh grid battery was installed in China in 2023. By 2025, sodium-ion battery packs remained 30% more expensive than lithium iron phosphate (LFP) due to scaling. A 2025 report from the International Renewable Energy Agency (IRENA) suggested that sodium-ion battery cell costs could drop to $40/kWh, while LFP fell as far as $70/kWh. Energy storage manufacturer Pylontech obtained the first sodium-ion battery certificate[clarification needed] from TÜV Rheinland. Farasis Energy's JMEV EV3 (Youth Edition) produced the first serial-production A00-class electric vehicle equipped with sodium-ion batteries, with a 251 km range. Estonia's Freen launched a 10 kWh residential sodium-ion battery for solar and wind integration. HiNa Battery Technology Co., Ltd is, a spin-off from the Chinese Academy of Sciences (CAS). It leverages research conducted by Prof. Hu Yong-sheng's group at the Institute of Physics at CAS. HiNa's batteries are based on Na-Fe-Mn-Cu based oxide cathodes and anthracite-based carbon anode. In February 2023, the Chinese HiNA placed a 140 Wh/kg sodium-ion battery in an electric test car for the first time, the Sehol E10X. HiNa also revealed three sodium-ion products, the NaCR32140-ME12 cylindrical cell, the NaCP50160118-ME80 square cell and the NaCP73174207-ME240 square cell, with gravimetric energy densities of 140 Wh/kg, 145 Wh/kg and 155 Wh/kg respectively. The cycle life of Hina's Battery was reported to by 4,500 cycles in 2022. The company's goals were increasing specific energy to 180-200 Wh/kg and the cycle life to 8,000-10,000 cycles. CATL and BYD also made similar statements around the same time.
Altech
Australia's Altech is building a 120 MWh plant in Germany.
Altris AB
Altris AB was founded by Associate Professor Reza Younesi, his former PhD student, Ronnie Mogensen, and Associate Professor William Brant as a spin-off from Uppsala University, Sweden, launched in 2017 as part of research efforts from the team on sodium-ion batteries. The research was conducted at the Ångström Advanced Battery Centre led by Prof. Kristina Edström at Uppsala University. The company offers a proprietary iron-based Prussian blue analogue for the positive electrode in non-aqueous sodium-ion batteries that use hard carbon as the anode. Altris holds patents on non-flammable fluorine-free electrolytes consisting of NaBOB in alkyl-phosphate solvents, Prussian white cathode, and cell production. Clarios is partnering to produce batteries using Altris technology.
BASF/Mercedes
Germany invested €1.3 million in a sodium-ion project with BASF and Mercedes-Benz.
BYD
BYD in 2023 invested $1.4B USD into the construction of a sodium-ion battery plant in Xuzhou with an annual output of 30 GWh.
CATL
Chinese battery manufacturer CATL announced in 2021 that it would bring a sodium-ion based battery to market by 2023. It uses Prussian blue analogue for the positive electrode and porous carbon for the negative electrode. They claimed a specific energy density of 160 Wh/kg in their first generation battery. CATL, the world's biggest lithium-ion battery manufacturer, announced in 2022 the start of mass production of SIBs. Chery Automobile became their first customer in 2023. In 2024, CATL unveiled the Freevoy hybrid chemistry battery pack for use in hybrid vehicles with a mix of sodium ion and lithium ion cells. This battery pack features an expected range of over 400 kilometres (250 mi), 4C fast charging capability, the ability to be discharged at −40 °C (−40 °F), and no difference to the driving experience at −20 °C (−4 °F). By 2025, around 30 different hybrid vehicle models are expected to be equipped with this pack.
Faradion Limited
Faradion Limited is a subsidiary of India's Reliance Industries. Its cell design uses oxide cathodes with hard carbon anode and a liquid electrolyte. Their pouch cells have energy densities comparable to commercial Li-ion batteries (160 Wh/kg at cell-level), with good rate performance up to 3C, and cycle lives of 300 (100% depth of discharge) to over 1,000 cycles (80% depth of discharge). Its battery packs have demonstrated use for e-bike and e-scooter applications. They demonstrated transporting sodium-ion cells in the shorted state (at 0 V), eliminating risks from commercial transport of such cells. It is partnering with AMTE Power plc (formerly known as AGM Batteries Limited).
Imagem: Tang-Yeon Hwang, Seung-Taek Myung, Yang-Kook Sun · BY · Openverse
CATL work with Li Auto, develops, manufactures, and sells premium smart EVs, will integrate these fast-charging sodium-ion batteries into upcoming EV models. As of early 2026, CATL and Chinese EV manufacturer Changan Automobile plan on launching a sodium-ion EV in mid-2026, the Changan Nevo A06. The battery's power density is expected to be comparable to that of contemporary LFP batteries. Nevo A06 is featuring initially a 45 kWh sodium-ion battery (Naxtra). BAIC Group Announced an update of their sodium-ion battery in march 2026. The battery can do 450 km in single charge under CLTC test condition. What makes it stand out is the charging speed - it uses 4C ultra-fast charging and gets empty to full in around 11 minutes
