Application of materials based on group VB elements in sodium-ion batteries: A review

Owing to their high redox activity, abundant resource, and low cost, compounds based on group VB elements (V, Nb, and Ta) are promising electrode materials for an array of energy storage devices. Moreover, their open structure benefits transportation and accommodation of alkali Na+ ions, rending them particularly appealing for cost-effective sodium-ion batteries (SIBs). In the last decade, these materials have evoked intensive investigations in SIBs, serving as either cathode, anode, or both depending on their sodiation degree and redox potential. Exciting progress has been made, but significant gaps in our knowledge still remain. Their practical application in SIBs remains unclear and thus calls for further efforts to settle several technical challenges in terms of poor conductivity, unstable cycling, and inefficient charge storage. In this perspective, a brief overview is given of recent progress on how to solve these technical issues and envision their bright future in SIBs, which may serve as a source to inspire researches on relevant topics. (C) 2018 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.