Unlocking Rapid and Robust Sodium Storage Performance of Zinc-Based Sulfide via Indium Incorporation

Zinc sulfide (ZnS) exhibits promise in sodium-ion batteries (SIBs) because of its low operation voltage and high theoretical specific capacity. However, pristine ZnS is not adequate in realizing rapid and robust sodium storage owing to its low reversibility, poor structure stability, and sluggish kinetics. To date, most efforts focus on utilizing carbonaceous incorporation to improve its electrochemical performances. Nevertheless, it remains an arduous challenge for realizing superior rate capability while obtaining stable cycling. Herein, inspired by the crystal structure of hexagonal ZnIn2S4, which possesses an intrinsic layered feature with larger unit-cell volume versus that of ZnS, indium incorporation is thus deployed as an immediate remedy. In/ex situ investigations combined with density functional theory calculations are conducted to reveal the superior kinetics, high reversibility, and good structure stability of ZnIn2S4. Notably, the formed indium-based derivatives during cycling manifest a Na+ (de)intercalation process, thereby exciting a synergetic mechanism to stabilize electrochemical cycling. As a result, the electrochemical performances of Zn-based sulfide are significantly improved via the indium incorporation. Furthermore, a full cell based on the ZnIn2S4 anode with the superior electrochemical performance is developed. This work provides an effective tactic of heteroatom incorporation for optimizing structure as well as exciting a complementary reaction process toward developing superior anodes for high-performance alkali-ion batteries.