Synergizing Phase and Cavity in CoMoOxSy Yolk-Shell Anodes to Co-Enhance Capacity and Rate Capability in Sodium Storage

Abstract

Sodium‐ion batteries (SIBs) have been recognized as the promising alternatives to lithium‐ion batteries for large‐scale applications owing to their abundant sodium resource. Currently, one significant challenge for SIBs is to explore feasible anodes with high specific capacity and reversible pulverization‐free Na+ insertion/extraction. Herein, a facile co‐engineering on polymorph phases and cavity structures is developed based on CoMo‐glycerate by scalable solvothermal sulfidation. The optimized strategy enables the construction of CoMoOxSy with synergized partially sulfidized amorphous phase and yolk-shell confined cavity. When developed as anodes for SIBs, such CoMoOxSy electrodes deliver a high reversible capacity of 479.4 mA h g-1 at 200 mA g-1 after 100 cycles and a high rate capacity of 435.2 mA h g-1 even at 2000 mA g-1, demonstrating superior capacity and rate capability. These are attributed to the unique dual merits of the anodes, that is, the elastic bountiful reaction pathways favored by the sulfidation‐induced amorphous phase and the sodiation/desodiation accommodatable space benefits from the yolk-shell cavity. Such yolk-shell nano‐battery materials are merited with co‐tunable phases and structures, facile scalable fabrication, and excellent capacity and rate capability in sodium storage. This provides an opportunity to develop advanced practical electrochemical sodium storage in the future.