Valence Electronic Modulation Induced by Reinforcing Interfacial Coupling for Expediting Sulfur Redox in Li─S Batteries

Abstract The practical application of rechargeable Lithium−sulfur (Li−S) batteries has been suffering from the serious “shuttle effect” of soluble lithium polysulfides (LiPSs) and slow electrochemical kinetics, the development of high‐efficiency electrocatalysts still remains a challenge. Herein, quasi‐plane heterostructures composed of vertically aligned metallic 1T‐MoSe 2 nanosheets evenly distributed on topological insulator Bi 2 Se 3 substrates (1T‐MoSe 2 /Bi 2 Se 3 ) are designed through two‐step hot‐injection and solvothermal method. In comparison with 2H‐MoSe 2 , the incomplete paired orbitals of the attached 1T‐MoSe 2 on lamellar Bi 2 Se 3 surface contribute to the establishment of stronger interfacial coupling and give rise to the valence electron modulation between Mo 4 d and Bi 6 p orbits in the heterostructures, thus conduce to weak the S‐S bonding energy and reduce the diffusion energy barrier of LiPSs. Theoretical and experimental evaluations further elucidate the enhanced chemical affinity and superior catalytic performance toward LiPSs. Remarkably, the assembled Li−S batteries with 1T‐MoSe 2 /Bi 2 Se 3 modified separator exhibits a long‐term cycling stability with only 0.039% capacity decay per cycle at 1 C over 1000 cycles. This study emphasizes the importance of interface design combined with phase engineering for the industrial application of Li−S batteries.