Zr2CSSe Janus MXene as electrode materials for metal (Na, K, Mg, Ca) ion batteries: A DFT study

Developing advanced anode materials for alternative energy carriers like Na, Mg, and Ca is crucial for reducing costs and enhancing energy density of batteries. Janus Zr 2 CSSe MXene, a Two-dimensional (2D) transition metal carbide, exhibits exceptional electrochemical performances for multivalent ion batteries. Density functional theory (DFT) calculations reveal high theoretical capacities of 526 mAh g -1 for Na and 1052 mAh g -1 for Mg and Ca, with low open-circuit voltages of 0.51, 0.15, and 0.25 V, respectively. The material shows low diffusion barriers of 0.149 and 0.114 eV for Na and K, indicating rapid ion transport. Compared to conventional 2D materials, including graphite, M 2 C-type MXenes, and other Janus structures, Zr 2 CSSe demonstrates superior capacity and versatility. Its asymmetric Janus structure generates a built-in electric field that enhances charge carrier migration and reduces diffusion barriers, offering novel insights into the role of surface asymmetry in tuning electrochemical properties. With excellent conductivity, high capacities, low operating voltages, and fast ion diffusion, Zr 2 CSSe may act as a promising candidate for the next-generation energy storage technologies, having significant advantages over existing anode materials. This study advances the understanding of ion transport mechanisms and provides a framework for designing high-performance anode materials in the field of surface and interface science.