First-principles insights into the Janus MoPC monolayer as a promising anode for sodium-ion batteries.

The development of high-performance anode materials is critical for advancing next-generation sodium-ion batteries. Using comprehensive density-functional-theory calculations, we reveal that the Janus MoPC monolayer possesses a notable combination of structural stability, fast ion transport, and high Na storage capability. Specifically, the proposed MoPC monolayer is predicted to exhibit robust mechanical and thermal stability together with intrinsic metallic conductivity. Na adsorption is energetically favorable across a wide range of coverages, and Na+ migration proceeds with an ultralow barrier of 0.06 eV along the most preferred pathway, suggesting favorable intrinsic diffusion under idealized conditions. The monolayer can accommodate up to six Na layers with a low and relatively stable calculated open-circuit voltage profile, yielding a high theoretical capacity of 1157.46 mAh g-1. Crucially, the MoPC monolayer preserves its metallic character even at high sodiation levels, ensuring electronic conductivity throughout battery operation. Overall, our findings indicate that Janus MoPC is a viable two-dimensional anode candidate for sodium-ion batteries with high Na storage capability and intrinsically favorable Na transport.