A 3.8-V earth-abundant sodium battery electrode

Abstract

Rechargeable lithium batteries have ushered the wireless revolution over last two decades and are now matured to enable green automobiles. However, the growing concern on scarcity and large-scale applications of lithium resources have steered effort to realize sustainable sodium-ion batteries, Na and Fe being abundant and low-cost charge carrier and redox centre, respectively. However, their performance is limited owing to low operating voltage and sluggish kinetics. Here we report a hitherto-unknown material with entirely new composition and structure with the first alluaudite-type sulphate framework, Na2Fe2(SO4)3, registering the highest-ever Fe3+/Fe2+ redox potential at 3.8 V (versus Na, and hence 4.1 V versus Li) along with fast rate kinetics. Rare-metal-free Na-ion rechargeable battery system compatible with the present Li-ion battery is now in realistic scope without sacrificing high energy density and high power, and paves way for discovery of new earth-abundant sustainable cathodes for large-scale batteries.

Boron Substituted Na3V2(P1−xBxO4)3 Cathode Materials with Enhanced Performance for Sodium‐Ion Batteries

“…In the past few years, many compounds including layer‐structured oxide and polyanionic phosphates have been investigated to find a suitable cathode material for reversible and rapid intercalation/deintercalation of Na + 7, 8, 9, 10, 11, 12, 13, 14. Among them, sodium super ion conductor (NASICON) structured Na 3 V 2 (PO 4 ) 3 with 3D open framework and large tunnels for Na + migration has aroused an extensive interest as cathode materials for SIBs owing to its superiority of good stability, moderate potential plateau, high energy density, and so on 14, 15, 16, 17, 18.…”

Polyanion‐Type Electrode Materials for Sodium‐Ion Batteries

“…Because of the thermal decomposition of SO 4 2− above 400 °C, a low‐temperature solid‐state method below 350 °C was used by Yamada and his group to prepare an entirely new alluaudite‐type sulfate framework, Na 2 Fe 2 (SO 4 ) 3 104. Unlike typical NASICON‐related structures with corner‐sharing FeO 6 octahedra, Na 2 Fe 2 (SO 4 ) 3 forms a unique alluaudite‐type framework, with edge‐sharing FeO 6 octahedra.…”

“…b) Electrode properties of Na 2‐x Fe 2 (SO 4 ) 3 in an Na cell. Reproduced with permission 104. Copyright 2014, Nature Publishing Group.…”

A Safer Sodium‐Ion Battery Based on Nonflammable Organic Phosphate Electrolyte

“…Similar to their Li counterparts,1 though sodium‐based system has similar electrochemical reaction characteristics compared to lithium‐based one, the larger ionic radius for sodium ion cause sluggish kinetics and volume change during Na storage, leading to lower capacity, poor cycling and rate properties of the Na storage materials. Recently, major efforts have been devoted to promote the electrochemical performance of Na storage materials, for example, Na x MO 2 ,2, 3, 4, 5, 6, 7, 8, 9, 10 polyanionic framework compounds,11, 12, 13, 14, 15, 16, 17, 18, 19 hexacyanoferrate,20, 21, 22, 23, 24, 25, 26, 27 for the cathode materials, and hard carbons,28, 29, 30, 31, 32, 33 alloys,34, 35, 36, 37, 38, 39, 40, 41 oxides,42, 43 sulfides37, 44, 45, 46 for the anode materials.…”