Atomic insights into the electrocatalytic properties of LaBO3 perovskite oxides for lithium–sulfur battery performance

Abstract

The intricate shuttle effect and sluggish conversion kinetics of lithium polysulfides (Li₂S_n, n = 1, 2, 4, 6, and 8) present significant challenges for the practical applications of lithium–sulfur batteries (LSBs). Introducing electrocatalysts to enhance the anchoring ability for Li₂S_n and accelerate its conversion is an effective strategy. To gain a deeper understanding of the underlying mechanisms of the anchoring effect and to identify optimal electrocatalytic materials for enhancing the performance of LSBs, the interactions between Li₂S_n and electrocatalysts should be studied at the atomic level. In this study, density functional theory calculations were performed to explore cubic LaBO₃ (B = Cr, Mn, Fe, Co, and Ni) perovskite oxides as potential electrocatalysts for boosting the electrochemical performance of LSBs. The results show that LaFeO₃ exhibits the lowest energy barrier (0.37 eV) for the rate-determining step of the sulfur reduction reaction, while LaCoO₃ achieves the lowest decomposition energy barrier for Li₂S (1.67 eV) during sulfur oxidation, effectively facilitating Li₂S dissociation. Further structural deformation and charge transfer analyses demonstrate that LaBO₃ (B = Cr, Mn, Fe, and Co) effectively activates the O and B sites by enabling O to capture electrons initially transferred from Li to S. This process promotes the formation of Li–O and B–S bonds, thereby mitigating the shuttle effect, weakening the Li–S bonds, and enhancing the redox kinetics of LSBs. These findings offer valuable insights for the future design of more efficient perovskite-based electrocatalysts.