Optimizing the Performance of Sodium-Ion Battery through Suppressing ZnS Anode Alloy Reaction.

Zinc sulfide (ZnS) is a promising anode material for sodium-ion batteries (SIBs) due to its high theoretical capacity and cost-effectiveness. However, the alloying reaction of ZnS causes severe volume expansion, leading to material pulverization and capacity decay. To address this, a sandwich-structured ZnS/porous MXene (ZnS/PMX) composite is designed, where ZnS nanoparticles are anchored on PMX porous layers via ZnOTi interfacial bonding. The nanoporous structure of PMX creates vertical ion transport pathways, enabling faster sodium-ion diffusion and overcoming the limitations of conventional 2D MXene. Additionally, the confinement effect of PMX suppresses the alloying reaction of ZnS, enhancing its structural stability. As an SIB anode, ZnS/PMX maintains capacities of 414.8 mA h g^{- 1} after 2100 cycles at 5.0 A g^{- 1}, 322.9 mA h g^{- 1} after 3300 cycles at 10.0 A g^{- 1}, and 276.9 mA h g^{- 1} after 4100 cycles at 20.0 A g^{- 1}. This performance benefits from the confinement effects of PMX, which effectively suppresses the alloying reaction and enhances ZnS stability. The results shed new light on the design of metal sulfide/MXene hybrid materials for alkali metal batteries.