Cation-Vacancy Engineering Modulated Perovskite Oxide for Boosting Electrocatalytic Conversion of Polysulfides

Lithium-sulfur batteries face challenges like polysulfide shuttle and slow conversion kinetics, hindering their practical applications in renewable energy storage and electric vehicles. Herein, a solution to solve this issue is reported by using a cation vacancy engineering strategy with rational synthesis of La-deficient LaCoO₃ (LCO-V_La). The introduction of cation vacancies in LCO-V_La modifies the geometric structure of coordinating atoms, exposing Co-rich surface with more catalytically active surfaces. Meanwhile, the d-band center of LCO-V_La shifts toward the Fermi level, enhancing polysulfide adsorption. Furthermore, multivalent cobalt ions (Co³⁺/Co⁴⁺) induced by charge compensation enhance the electrical conductivity of LCO-V_La, accelerating electron transfer processes and improving catalytic performance. Theoretical calculations and experimental characterizations demonstrate that La-deficient LCO-V_La effectively suppresses the polysulfide shuttle, reduces the energy barrier for polysulfide conversion, and accelerates redox reaction kinetics. LCO-V_La-based batteries demonstrate exceptional rate performance and cycling stability, retaining 70% capacity after nearly 500 cycles at 1.0 C, with a minimal decay rate of 0.055% per cycle. These findings highlight the significance of cation vacancy engineering for exploring precise structure-activity relationships during polysulfides conversion, facilitating the rational design of catalysts at the atomic level for lithium-sulfur batteries.