P doping adjusts the coordination structure of single atoms to accelerate the catalytic bidirectional redox reaction in Li-S batteries

Carbon materials loaded with single-atom catalysts (SACs) exhibit significant potential for catalyzing sulfur redox reactions and inhibiting polysulfide shuttling effects. However, traditional single-atom structures with nitrogen coordination face limitations in addressing the challenges of lithium-sulfur (Li-S) batteries, as the strong electronegativity of nitrogen diminishes the activity of catalytic sites. Herein, a Co single-atom graphene-like carbon nanosheet with both nitrogen and phosphorus coordination is synthesized (Co-N2P2/C). Both experimental and theoretical studies reveal that the Co-N2P2 single-atom structure exhibits enhanced capabilities for adsorbing lithium polysulfides and catalyzing their bidirectional conversion. The introduction of phosphorus induces an asymmetric shift in the electronic structure of the single atom, optimizing electron transport. The layered structure of the nanosheets provides an exceptionally high specific surface area, facilitating the exposure of catalytic sites. Furthermore, the S/Co-N2P2/C soft-packed battery retained a weight energy density of 334 Wh<middle dot>kg(-1) after 100 cycles, demonstrating its practical application value. This research offers valuable guidance for advancing efficient SACs in Li-S battery development.