Enhancing electrocatalytic effect of weak crystalline induced lattice strain of tin oxide for lithium sulfur batteries

Oxide-coupled carbon-based composite materials, combining high conductivity and excellent electrocatalytic activity, are regarded as crucial host materials for achieving high-rate performance in lithium-sulfur batteries. However, the influence of oxide crystallinity on the electrochemical behavior of lithium polysulfides (LiPSs) remains largely unexplored, leaving the mechanism of interaction between crystallinity variations and catalytic activity insufficiently understood. In this study, we construct tin oxide with varying degrees of crystallinity on the surface of nitrogen-doped graphitized carbon materials (SnO 2 @NC). Utilizing confocal microscopy and in situ Raman spectroscopy, we visually demonstrate the transformation process of LiPSs, accurately identifying the positive facilitation of lithium polysulfide conversion by the changes in weak crystallinity. Through geometric phase analysis, it is revealed that weak crystallinity induces a 60 % variation in lattice strain, optimizing the adsorption energy of LiPSs, leading to superior sulfur retention effects and enhanced electrocatalytic activity. These findings enable the development of a stable sulfur-storage cathode (SnO 2 @NC-60 %/S) operating under high rates. This fundamental understanding of the inherent relationships provides a viable crystallographic modulation strategy for the design of multifunctional hosts in lithium-sulfur battery cathodes.