Long‐Term Cycling Stability of Cobalt sulfide Nanosheets for High‐Performance Magnesium‐Ion Batteries

Rechargeable Magnesium ion batteries (RMIBs) are considered one of the most promising energy storage devices due to their low cost, dendrite‐free nature, and ecofriendliness. However, sluggish kinetics, irreversible structural changes, short cycle life, and low capacity of cathodes hinder their practical applications. Herein, Cobalt sulfide (CoS 2 ) nanosheets are synthesized using microwave method followed by chemical vapor deposition to serve as cathode material for RMIBs. CoS 2 nanosheets exhibit excellent electrochemical performance, providing a high specific capacity of 432 mAh g − 1 at 100 mA g − 1 current density. Moreover, CoS 2 also demonstrates a long‐term operating stability over 2000 cycles giving 284 mAh g − 1 capacity at a current density of 500 mA g − 1 with approximately 96% capacity retention. Sustainable cathodic performance is the most desirous feature for commercialization. The density functional theory and experimental results reveal that the robust electrochemical performance of CoS 2 as a cathode is attributed to the high surface area of its sheet‐like morphology. This work provides meaningful insights regarding morphological limitations and opportunities of CoS 2 cathode for applications in high‐performance RMIBs.