Promoting the Potassium Storage of 2D Layered Indium Sulfide Through Zinc Incorporation and MXene Coupling

Abstract Metal sulfides have garnered lots of attention as prospective anode materials for potassium‐ion batteries (PIBs), yet their practical application is hindered by sluggish reaction kinetics and structural degradation during cycling. Herein, a two‐dimensional layered indium sulfide (In 1.95 S 3 ) is reported for the first time with strategic zinc incorporation (ZnIn 2 S 4 ) and MXene coupling, aiming at addressing these challenges. The ZnIn 2 S 4 /MXene (ZIS/MXene) heterostructure features vertically aligned ZIS nanoflakes on MXene nanosheets, rendering high K + accessibility, rapid electron transport, and robust structural integrity. The water/glycerin molecule intercalation and strong interfacial coupling between ZIS and MXene induce significant interlayer spacing expansion, facilitating efficient K + diffusion. Furthermore, the zinc incorporation notably reinforces the thermal stability, narrows the bandgap, and lowers the K + diffusion barrier, as corroborated by experimental data and theoretical simulations. These improvements confer the ZIS/MXene anode with high reversible capacity (424.5 mAh g −1 at 0.1 A g −1 ), superior rate performance (185.2 mAh g −1 at 5 A g −1 ), and outstanding durability (84.8% capacity retention after 1000 cycles at 1 A g −1 ). In situ and ex situ characterizations reveal that the ZIS/MXene anode follows a multistep intercalation‐conversion‐alloying reaction mechanism, accompanied by a highly reversible nanoflakes to nanodots morphological transformation.