Regulating the orbital hybridization to induce asymmetrical catalysis for efficient reversible sodium conversion storage

Carbon-supported single-atom catalysts (C-SACs) have been demonstrated as a strategy to promote the reversible conversion reaction of metal sulfide anodes in sodium-ion batteries (SIBs). However, the design principle of promising C-SACs remains lacking for obtaining highly reversible metal sulfide anodes. We designed a phosphorus-doped carbon-supported single-atom Mn catalyst (PC-SAMn) with an asymmetrical dual active center. The sulfiphilic Mn and sodiophilic P active centers adsorb discharged Na₂S through Mn–S d-p and P–Na s-p orbital hybridizations. The asymmetrical dual active center induced the asymmetrical adsorption configuration of Na₂S, which efficiently weakened Na–S bond strength and facilitated the decomposition of Na₂S during charging. As a result, the designed catalyst enables typical MoS₂ with a record-high compositional reversible degree of 89.61% and a low capacity decay ratio of only 0.18% per 100 cycles during 2000 cycles. The research establishes the “orbital hybridization-molecular structure-catalytic activity” relationship for guiding the design of highly reversible conversion-type materials.