Promoting spherical epitaxial deposition of solid sulfides for high-capacity Li-S batteries

The epitaxial deposition of solid sulfides prefers lateral deposition driven by the superior charge transfer of the conductive substrate to produce a continuous insulating 2D film. This situation not only disables the adsorbing host from controlling the dissolved PSs, but also terminates electrochemical redox when the mass transport and electron transfer are completely blocked by the non-conductive layer. Here, we present that single-atom Co is of significance to control the epitaxial deposition of solid sulfides to promote spherical cumulative deposition with 3D morphology. On the carbon paper (CP), the deposition shows the lateral deposition mode with a much lower capacity. On the single-atom Co decorated carbon paper (CoSAs-CP), it shows the spherical cumulative deposition mode with a high capacity reaching up to its theoretical value. The experimental studies and theoretical calculations reveal that single-atom Co can reconstruct the electronic structure of solid intermediates owing to the d-p hybridization associated with an electron feedback coupling mechanism, which benefits the non-locality of electrons and octahedron-tetrahedron fields of solid intermediates, promoting both the electron transfer and Li transport of longitudinal deposition to balance the lateral deposition so as to sustain the spherical epitaxial deposition.