Chemomechanics Engineering Promotes the Catalytic Activity of Spinel Oxides for Sulfur Redox Reaction

Abstract

AbstractCooperative catalysis is a promising approach to enhance the sluggish redox kinetics of lithium polysulfides (LiPSs) for practical lithium–sulfur (Li–S) batteries. However, the elusory synergistic effect among multiple active sites makes it challenging to accurately customize the electronic structure of catalysts. Herein, a strategy of precisely tailoring eg orbitals of spinel oxides through chemomechanics engineering is porposed to regulate LiPSs retention and catalysis. By manipulating the regulable cations in MnxCo3‐xO4, it is theoretically and experimentally revealed that the lattice strain induced by the Jahn–Teller active and high‐spin Mn3+ at octahedral (Oh) sites can increase the eg occupancy of low‐spin Co3+Oh, which effectively regulates the chemical affinity toward LiPSs and establishes an unblocked channel for intrinsic charge transfer. This leads to a volcano‐type correlation between the eg occupancy at Oh sites and sulfur redox activity. Benefitting from the cooperative catalysis of dual‐active sites, MnCo2O4 with an average eg occupancy of 0.45 affords the most appropriate adsorption strength and rapid redox kinetics toward LiPSs, leading to remarkable rate performance and capacity retention for the assembled Li–S batteries. This work demonstrates the promise of chemomechanics engineering for optimizing the eg occupancy to achieve efficient sulfur redox catalysts.