Deciphering Enhanced Solid-State Kinetics of Li–S Batteries via Te Doping

Abstract

Owing to their high gravimetric energy, low cost, and wide availability of required materials, Li–S batteries (LSBs) are considered as a promising next-generation energy storage technology. However, the sluggish redox kinetics and dissolution of lithium polysulfides during the electrochemical reactions are key problems to overcome. The improvement of the long-term cycle life of LSBs solely by converting insoluble solid-state electrolyte-soluble lithium polysulfides (LiPSs) (Li2Sx, where 1 ≤ x ≤ 2, 836 mAh g–1) is an ingenious method, but solid-state LiPS conversion has sluggish redox kinetics owing to the intrinsically low electrical conductivity of solid-state LiPS compounds (Li2S and Li2S2). This study applied Te doping to S cathodes and conducted experimental and theoretical analyses on the Te-doped solid-state LiPSs to investigate the effect of Te on the redox kinetics of the solid-state LiPS conversions for high-performance LSBs. The qualitative and quantitative electrochemical characterization demonstrated that Te induced an increase in the kinetics. Furthermore, the enhanced kinetics were explained at the atomic scale by the theoretical thermodynamics and chemomechanics investigations. The design of high-performance LSBs will benefit the strong understanding of Te-doped S electrodes in solid-state conversion.