Review and Recent Advances in Metal Compounds as Potential High-Performance Anodes for Sodium Ion Batteries

Along with great attention to eco-friendly power solutions, sodium ion batteries (SIBs) have stepped into the limelight for electrical vehicles (EVs) and grid-scale energy storage systems (ESSs). SIBs have been perceived as a bright substitute for lithium ion batteries (LIBs) due to abundance on Earth along with the cost-effectiveness of Na resources compared to Li counterparts. Nevertheless, there are still inherent challenges to commercialize SIBs due to the relatively larger ionic radius and sluggish kinetics of Na+ ions than those of Li+ ions. Particularly, exploring novel anode materials is necessary because the conventional graphite anode in LIBs is less active in Na cells and hard carbon anodes exhibit a poor rate capability. Various metal compounds have been examined for high-performance anode materials in SIBs and they exhibit different electrochemical performances depending on their compositions. In this review, we summarize and discuss the correlation between cation and anion compositions of metal compound anodes and their structural features, energy storage mechanisms, working potentials, and electrochemical performances. On top of that, we also present current research progress and numerous strategies for achieving high energy density, power, and excellent cycle stability in anode materials.