DFT investigation of Na-ion interaction with Janus 1T-HfSTe monolayer for sodium-ion battery anodes

and a relatively low average open-circuit voltage of 0.33 V, which is suitable for anode operation. Notably, the HfSTe monolayer maintains its metallic character even at high sodiation levels, accompanied by a moderate volume expansion of 10.55%. These results highlight the Janus HfSTe monolayer as a promising anode candidate for high-performance sodium-ion batteries.