NiCo2S4/Co9S8 heterostructures on MXene nanosheets boost OH− adsorption for high-capacity and long-cycling alkaline Zn batteries

Nickel/cobalt-based materials have attracted significant interest as cathode materials for aqueous alkaline Zn batteries (AAZBs) due to their high theoretical capacity and natural abundance. However, their practical application is hindered by unsatisfied discharge capacity and poor cycling stability, primarily caused by insufficient active sites and sluggish reaction kinetics. Herein, an effective approach is demonstrated to achieve high-efficiency and stable cathode for AAZBs by anchoring the NiCo 2 S 4 /Co 9 S 8 heterostructures on MXene nanosheets (NCS/CS@MXene), accompanied with morphological optimization. The introduced MXene significantly increases the effective active area and electrical conductivity of the composite. Consequently, the NCS/CS@MXene//Zn battery delivers a high areal capacity of 1.01 mAh cm −2  at 2 mA cm −2 , excellent cycling stability of 2500 cycles with only 0.00416% of capacity degradation per cycle, and nearly 100% coulombic efficiency.