Oxygen-vacancy-reinforced perovskites promoting polysulfide conversion for lithium-sulfur batteries

Lithium-sulfur batteries (LSBs) are considered to be one of the most promising energy storage systems because of the ultrahigh energy density. However, their shuttle effect and slow redox kinetics seriously hinder the development of LSBs. To solve these issues, the perovskite La_1-xSr_xMnO_3-δ (x = 0-0.5) with different oxygen vacancy concentrations were prepared by a facile liquid-phase synthesis and followed by the thermal annealing. The La_1-xSr_xMnO_3-δ can not only anchor lithium polysulfides (LiPSs), but also catalyze the conversion of LiPSs. The detailed kinetic analysis and density functional theory calculations reveal that the optimal level of oxygen vacancies can effectively increase the binding energy between perovskites and LiPSs, and effectively promote the LiPS conversion kinetics. The S/La_0.6Sr_0.4MnO_3-δ cathode with a moderate oxygen vacancy concentration exhibits high rate performance and ultrahigh capacity retention of 93.2% after 150 cycles at 0.1 C, which provides a potential for practical applications of LSBs. This work reveals the application of perovskite materials in the development of advanced LSBs.