State-of-the-Art Electrode Materials for Sodium-Ion Batteries

Abstract

Sodium-ion batteries (SIBs) were investigated as recently as in the seventies. However, they have been overshadowed for decades, due to the success of lithium-ion batteries that demonstrated higher energy densities and longer cycle lives. Since then, the witness a re-emergence of the SIBs and renewed interest evidenced by an exponential increase of the publications devoted to them (about 9000 publications in 2019, more than 6000 in the first six months this year). This huge effort in research has led and is leading to an important and constant progress in the performance of the SIBs, which have conquered an industrial market and are now commercialized. This progress concerns all the elements of the batteries. We have already recently reviewed the salts and electrolytes, including solid electrolytes to build all-solid-state SIBs. The present review is then devoted to the electrode materials. For anodes, they include carbons, metal chalcogenide-based materials, intercalation-based and conversion reaction compounds (transition metal oxides and sulfides), intermetallic compounds serving as functional alloying elements. For cathodes, layered oxide materials, polyionic compounds, sulfates, pyrophosphates and Prussian blue analogs are reviewed. The electrode structuring is also discussed, as it impacts, importantly, the electrochemical performance. Attention is focused on the progress made in the last five years to report the state-of-the-art in the performance of the SIBs and justify the efforts of research.

Na+ diffusion mechanism and transition metal substitution in tunnel-type manganese-based oxides for Na-ion rechargeable batteries

“…The majority of high performance sodium-ion cathodes reviewed in literature contains toxic and expensive elements like cobalt, vanadium or nichel. 2,3 Na 0.44 MnO 2 (NMO) is instead a well-investigated cathode material for NIBs based on earth's abundant and non-toxic elements. Unfortunately, NMO presents performance problems in long cycling tests due to Mn 3+ dissolution in the liquid electrolyte.…”

Validating the Structural (In)stability of P3- and P2-Na0.67Mg0.1Mn0.9O2-Layered Cathodes for Sodium-Ion Batteries: A Time-Decisive Approach

“…Therefore, developing a cathode material with a low strain, which has weak or no phase transitions, remains a crucial challenge for developing a low-cost and commercialized device. Various approaches have been employed to improve the energy density of SIBs, such as using effectively engineered electrolytes and working at a high potential with a selection of suitable substitutions on a host material, among others. − Among the various host cathodes for SIBs, layered manganese oxides (Na x MnO 2 ) are promising due to their low cost, wide potential operating region, high theoretical capacity, and ease of large-scale synthesis. − …”

The advent of manganese-substituted sodium vanadium phosphate-based cathodes for sodium-ion batteries and their current progress: a focused review

“…32 Among the various types of cathodes explored for use in SIBs, NASICON-type cathodes have been highly favored due to their superior structural stability, extreme air stability, and stable voltage plateau. 33,34 In particular, Na 3 V 2 (PO 4 ) 3 (NVP) has served as a common NASICON-type cathode for SIBs over the decades. 35,36 However, inherent electronic conductivity issues and the use of unfavorable vanadium raw materials make NVP unsuitable for use in practical SIBs.…”