Alloying Strategy Regulating Size and Electronic Structure of Mo0.25Nb0.75Se2 to Achieve High‐Performance Lithium–Sulfur Batteries

The utilization of catalysts in lithium−sulfur batteries has proven to be an efficacious avenue for enhancing the kinetics of polysulfide conversion. Specially, the size and electronic structure of catalysts play a pivotal role in harnessing the active sites and intrinsic catalysis activity. Outstanding MoSe2 and NbSe2 are selected from 16 universal transition metal selenides based on the proposed binary descriptor. Then, an alloying strategy is devised to prepare Mo0.25Nb0.75Se2 flakelets for further improvement of the intrinsic catalysis. The integration of density functional theory calculations and electrochemical analysis demonstrates that alloying Mo with Nb can regulate the surface energy and indexes of band match and lattice mismatch, thereby enabling Mo0.25Nb0.75Se2 to possess a small size, suitable adsorption energy and low reaction energy barrier. This optimization enhances the catalysis of sulfur reduction/evolution reaction and the reversible deposition/stripping of lithium. Consequently, an assembled Ah‐level pouch cell is realized with dramatic cycle stability. With the electrolyte/sulfur ratio of 2.36 μL mg S–1, the cell can deliver a high energy density of up to 505.4 Wh kgtotal−1. This work pioneers a universal strategy for sculpting the geometric configurations and electronic structures of catalysts, to achieve enhanced catalytic activity and precise interpretation of structure−activity relationships.