Sodium-ion battery

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Sodium-ion batteries (SIB) are a type of rechargeable metal-ion battery that uses sodium ions as charge carriers.[1][2][3]


Battery-grade salts of sodium are cheap and abundant, much more so than those of lithium. This makes them a cost-effective alternative especially for applications where weight and energy density are of minor importance such as grid energy storage for renewable energy sources such as wind- and solar power[1][2]

These cells can be completely drained (to zero charge) without damaging the active materials. They can be stored and shipped safely. Lithium-ion batteries must retain about 30% of charge during storage, enough that they could short-circuit and catch fire during shipment.[4]

Moreover, Sodium-ion batteries have excellent electrochemical features in terms of charge-discharge, reversibility, coulombic efficiency and high specific discharge capacity.[5]


In 2014 Aquion Energy offered a commercially available sodium-ion battery with cost/kWh capacity similar to a lead acid battery for use as a backup power source for electricity micro-grids.[6] According to the company, it was 85 percent efficient. Aquion Energy filed for Chapter 11 Bankruptcy in March 2017.

In 2015 researchers announced a device that employed the "18650" format used in laptops, LED flashlights and the Tesla Model S, among other products. Its energy density was claimed to be 90 Wh/Kg, a performance comparable to lithium iron phosphate battery.[7]

In 2016 other researchers announced a model for a device that used symmetric manganese dioxide electrodes in a saltwater bath, separated by a membrane that allowed Cl- to cross it. While charging, Na+ ions intercalated into the electrode on one side and Cl- ions migrated across the membrane, reducing salinity by 63%. While discharging, the Na+ ions left the electrode on one side while other Na+ ions entered it on the other side.[8][9]


Sodium ion cells have been reported with a voltage of 3.6 volts, able to maintain 115 Ah/kg after 50 cycles, equating to a cathode-specific energy of approximately 400 Wh/kg[10] Inferior cycling performance limits the ability of non-aqueous Na-ion batteries to compete with commercial Li-ion cells. In 2015 Faradion claimed to have improved cycling in full Na-ion pouch cells using a layered oxide cathode.[11]


SIBs store energy in chemical bonds of the anode. Charging the battery forces Na+ ions to de-intercalate from the cathode and migrate towards the anode. Charge balancing electrons pass from the cathode through the external circuit containing the charger and into the anode. During discharge the process reverses. Once a circuit is completed electrons pass back from the anode to the cathode and the Na+ ions travel back to the cathode.[12]


Aquion originally used a mix of activated carbon and titanium phosphate NaTi2(PO4)3 that relied mostly on pseudocapacitance to store charge, resulting in a low energy density and a tilted voltage-charge slope.[13] In many ways, titanium phosphate is similar to iron phosphate used in some other batteries, but with a low (anodic) electrode potential.The initial electrolyte was an aqueous sodium sulphate solution. Later a more soluble <5M NaClO4 was used.[14]

Using NaxC6 as the anode, the average voltage on the low potential plateau was higher for Na cells than Li cells. Unlike traditional Li cells, which make use of an intercalated graphite anode with a fully lithiated stoichiometry of LiC6, Na capacity in graphite is very low. This is because of a weak binding between Na and carbon.[15] In fact, quantum-mechanical calculations show that among the alkali and alkaline earth metals, Na and Mg generally have the weakest chemical binding to a given substrate, compared with the other elements in the same group of the periodic table.[15] The phenomenon arises from the competition between trends in the ionization energy and the ion–substrate coupling, down the columns of the periodic table.[15] For these reasons, carbon-based anodes rely on amorphous carbon that consists of spatially disoriented graphene sheets, defects and interstitial pores. These amorphous carbon allotropes can be categorized as hard or soft. Soft carbons can be transformed into graphite through annealing at high temperatures. Hard carbon materials can be derived from feedstocks such as: sugar, starch, fiber and certain polymers.[16]

Alloy anodes[edit]

Metal alloy anodes made of antimony (Sb), tin (Sn), phosphorus (P), germanium (Ge) and lead (Pb) have been studied. Carbon anodes provide organic complexes for the storage of Na+ ions, while alloyed anodes form inorganic complexes with the Na+ ions, such as Na3Sb, Na3Sn and Na3P. This capability gives alloy anodes greater theoretical capacity than carbon. Whereas amorphous carbon has shown capacity between 300-400 mAh g−1, Na3P has a theoretical capacity of 2596 mAh g−1. However, the alloying process requires a large volume of as much as 400%. This results in fractures and displaces the alloying material, which causes it to passivate and become 'dead weight', unable to accept sodium ions. Unchecked, these volume changes reduce cycle life. Much of anode alloy research focuses on mitigating volume changes and their negative effects .


In one study, tin-coated wood anodes replaced stiff anode bases. The wood fibers proved withstood more than 400 charging cycles. After hundreds of cycles, the wood ended up wrinkled but intact. Computer models indicated that the wrinkles effectively reduce stress during charging and recharging. Na ions move via the fibrous cell walls and diffuse at the tin film surface.[17][18]

Another study used MoS2/graphene composite paper as an electrode, yielding 230 Ah/kg with Coulombic efficiency reaching approximately 99%.[19][20][21]


Tests of Na2FePO4F and Li2FePO4F cathode materials indicated that a sodium iron phosphate cathode can replace a lithium iron phosphate cathode in a Li cell.[10] The lithium-ion and sodium-ion combination would lower manufacturing costs.[10]

P2-Na2/3[Fe1/2Mn1/2]O2 delivered 190  Ah/kg of reversible capacity in sodium cells using electrochemically active Fe3+/Fe4+ redox at room temperature.[22] Triclinic Na2FeP2O7 was examined as rechargeable sodium ion batteries by a glass-ceramics method. The precursor glass, also made of Na2FeP2O7, was prepared by melt-quenching. Na2FeP2O7 and exhibited 2.9 V, 88 Ah/kg.[23]

Separately, chromium cathodes employed the reaction:

NaF + (1−x)VPO4 + xCrPO4 → NaV1−xCrxPO4F

The effects of Cr doping on cathode performance materials was analyzed in terms of crystal structure, charge/discharge curves and cycle performance and indicated that the Cr-doped materials expressed better cycle stability. The initial reversible capacity was 83.3 Ah/kg and the first charge/discharge efficiency was about 90.3%. The reversible capacity retention of the material was 91.4% after the 20th cycle.[10][24]

Cathode materials First charge capacity (Ah/kg) First discharge capacity (Ah/kg) Capacity loss in the first cycle (Ah/kg) Reversible efficiency in the first cycle (%) Discharge capacity after 20 cycles (Ah/kg) Capacity retention ratio after 20 (%)
NaV0.92Cr0.08PO4F 83.3 75.2 8.1 90.3 68.8 91.4
NaV0.96Cr0.04PO4F 93.3 82.6 10.7 88.5 67.9 82.2
NaVPO4F 106.9 87.7 19.2 82.0 64.5 73.5

See also[edit]


  1. ^ a b Palomares, Veronica; et al. (2012). "Na-ion batteries, recent advances and present challenges to become low cost energy storage systems. In". Energy and Environmental Science. 5: 5884–5901. doi:10.1039/c2ee02781j. 
  2. ^ a b Pan, Huilin; et al. (2013). "Room-temperature stationary sodium-ion batteries for large-scale electric energy storage". Energy and Environmental Science. 6: 2338–2360. doi:10.1039/c3ee40847g. 
  3. ^ Hwang, Jang-Yeon; Myung, Seung-Taek; Sun, Yang-Kook (2017). "Sodium-ion batteries: present and future". Chem. Soc. Rev. 46: 3529–3614. doi:10.1039/C6CS00776G. 
  4. ^ Challenging Lithium-Ion Batteries With New Chemistry, Chemical & Engineering News, Alex Scott, 20 July 2015
  5. ^ Saadoune, I.; Difi, S.; Doubaji, S.; Edström, K.; Lippens, P. E. (2014-05-01). "Electrode materials for sodium ion batteries: A cheaper solution for the energy storage". 2014 International Conference on Optimization of Electrical and Electronic Equipment (OPTIM): 1078–1081. doi:10.1109/OPTIM.2014.6851038. 
  6. ^ Bullis, Kevin (November 14, 2014). "A Battery to Prop Up Renewable Power Hits the Market". Technology Review. Retrieved December 2014.  Check date values in: |access-date= (help)
  7. ^ Mack, Eric (November 28, 2015). "Researchers create sodium battery in industry standard "18650" format". Retrieved 2015-12-02. 
  8. ^ Smith, Kyle C.; Dmello, Rylan (2016-01-01). "Na-Ion Desalination (NID) Enabled by Na-Blocking Membranes and Symmetric Na-Intercalation: Porous-Electrode Modeling". Journal of the Electrochemical Society. 163 (3): A530–A539. doi:10.1149/2.0761603jes. ISSN 0013-4651. 
  9. ^ Lavars, Nick (2016-02-06). "Sodium battery contains solution to water desalination". Retrieved 2016-02-07. 
  10. ^ a b c d Ellis, B. L.; Makahnouk, W. R. M.; Makimura, Y.; Toghill, K.; Nazar, L. F. (2007). "A multifunctional 3.5V iron-based phosphate cathode for rechargeable batteries". Nature Materials. 6 (10): 749–53. doi:10.1038/nmat2007. PMID 17828278. 
  11. ^ Barker, J.; Heap, R.J.; Roche, N.; Tan, C.; Sayers, R.; Lui, Y. "Low Cost Na-ion Battery Technology" (PDF). Faradion Limited. Retrieved December 2014.  Check date values in: |access-date= (help)
  12. ^ Zumdahl, Steven (3 December 2007). Chemical Principles. Cengage Learning. p. 495. ISBN 0-618-94690-X. 
  13. ^ Whitacre, J. F. (2014). "A Polyionic, Large-Format Energy Storage Device Using an Aqueous Electrolyte and Thick-Format Composite NaTi2(PO4)3/Activated Carbon Negative Electrodes". Energy Technology. 3: 20–31. doi:10.1002/ente.201402127. 
  14. ^ Wu, Wei; Shabhag, Sneha; Chang, Jiang; Rutt, Ann; Whitacre, Jay F. (2015). "Relating Electrolyte Concentration to Performance and Stability for NaTi2(PO4)3/Na0.44MnO2 Aqueous Sodium-Ion Batteries" (PDF). Journal of the Electrochemical Society. 162 (6): A803–A808. doi:10.1149/2.0121506jes. 
  15. ^ a b c Liu, Yuanyue; Merinov, Boris V.; Goddard, William A. (5 April 2016). "Origin of low sodium capacity in graphite and generally weak substrate binding of Na and Mg among alkali and alkaline earth metals". Proceedings of the National Academy of Sciences. 113 (14): 3735–3739. doi:10.1073/pnas.1602473113. PMC 4833228Freely accessible. PMID 27001855. 
  16. ^ Stevens, D. A.; Dahn, J. R. (2000). "High Capacity Anode Materials for Rechargeable Sodium-Ion Batteries". Journal of the Electrochemical Society. 147 (4): 1271–3. doi:10.1149/1.1393348. 
  17. ^ "A battery made of wood: long-lasting, efficient, environmentally friendly". KurzweilAI. Retrieved 2013-06-25. 
  18. ^ Zhu, H.; Jia, Z.; Chen, Y.; Weadock, N.; Wan, J.; Vaaland, O.; Han, X.; Li, T.; Hu, L. (2013). "Tin Anode for Sodium-Ion Batteries Using Natural Wood Fiber as a Mechanical Buffer and Electrolyte Reservoir". Nano Letters. 13 (7): 3093–100. doi:10.1021/nl400998t. PMID 23718129. 
  19. ^ Indian-origin develops paper electrode for sodium-ion battery, The Economist Times, 30 January 2014
  20. ^ David, L.; Bhandavat, R.; Singh, G. (2014). "MoS2/Graphene Composite Paper for Sodium-Ion Battery Electrodes". ACS Nano. 8 (2): 1759–70. doi:10.1021/nn406156b. 
  21. ^ Johnson, D. (31 Jan 2014). "Graphene Composite Offers Critical Fix for Sodium-ion Batteries". IEEE Spectrum Nanoclast. 
  22. ^ Yabuuchi, N.; Kajiyama, M.; Iwatate, J.; Nishikawa, H.; Hitomi, S.; Okuyama, R.; Usui, R.; Yamada, Y.; Komaba, S. (2012). "P2-type Nax[Fe1/2Mn1/2]O2 made from earth-abundant elements for rechargeable Na batteries". Nature Materials. 11 (6): 512–7. doi:10.1038/nmat3309. 
  23. ^ Honma, T.; Togashi, T.; Ito, N.; Komatsu, T. (2012). "Fabrication of Na2FeP2O7 glass-ceramics for sodium ion battery" (pdf). Journal of the Ceramic Society of Japan. 120 (1404): 344–6. doi:10.2109/jcersj2.120.344. 
  24. ^ Zhuo, H.; Wang, X.; Tang, A.; Liu, Z.; Gamboa, S.; Sebastian, P. J. (2006). "The preparation of NaV1−xCrxPO4F cathode materials for sodium-ion battery". Journal of Power Sources. 160 (1): 698–703. doi:10.1016/j.jpowsour.2005.12.079.