Stable Lithium-Sulfur Batteries Ensured by GeS2 and α-S8 Lattice Matching During the Charge Process

Abstract

The charge process of lithium-sulfur batteries (LSBs) is a process in which molecular polarity decreases and the volume shrinks gradually, which is the process most likely to cause lithium polysulfides (LiPSs) loss and interfacial collapse. In this work, GeS₂ is utilized, whose (111) lattice plane exactly matches with the (113) lattice of α-S₈ , to solve these problems. GeS₂ can regulate the interconversion-deposition behavior of S-species during the charge process. Soluble LiPSs can be spontaneously adsorbed on the GeS₂ surface, then obtain electrons and eventually convert to α-S₈ molecules. More importantly, the α-S₈ molecules will crystallize uniformly along the (111) lattice plane of GeS₂ to maintain a stable cathode-electrolyte interface. Therefore, outstanding charge/discharge LSBs are successfully accomplished.

Keywords: GeS2; charge processes; interfacial stability; lattice matching; lithium-sulfur batteries.