Lattice Strain and Charge Localization Dual Regulation of Phosphorus-Doped CoSe₂/MXene Catalysts Enable Kinetics-Enhanced and Dendrite-Free Lithium-Sulfur Batteries

Phase engineering is considered an effective strategy to regulate the electrocatalytic activity of catalysts for Li–S batteries (LSBs). However, the underlying origin of phase-dependent catalytic ability remains to be determined, which significantly impedes the design principles of high-performance catalytic materials for LSBs. Herein, heteroatom-doped engineering can trigger phase transformation from mixed-phased cubic and orthorhombic cobalt diselenide into pure orthorhombic structure with a tensile strain and enhanced charge localization. The upshift of the d-band center and enhanced Bader charge at Se sites synergistically strengthen the interaction with Li and S sites in polysulfide species, thus endowing the transformed P-MoSe₂/MXene with high catalytic activity and uniform lithium deposition for LSBs. Consequently, the P-CoSe₂/MXene Li–S batteries demonstrate a high-rate capability of 603 mAh g⁻¹ at 4C, and an excellent cyclability of 652 mAh g⁻¹ at 1C over 500 cycles with a degradation rate of 0.076% per cycle. The work provides an in-depth insight into the fundamental design principles of effective catalysts for LSBs.