Lithiothermic‐Synchronous Construction of Mo‐Li2S‐Graphene Nanocomposites for High‐Energy Li2S//SiC Battery

Abstract

AbstractReducing the activation barrier and stabilizing the sulfur species of Li2S cathodes can ultimately enhance cell efficiency and the cycle life of S‐based Li‐ion batteries (LIBs). Here, a unique synchronous synthesis method is established that can simultaneously construct Li2S encapsulated in conductive protective layers, and accordingly propose a coordination effect of catalysis and domain restriction for Li2S cathodes. Typically, based on the lithiothermic reaction of 8Li + MoS2 + CS2 = 4Li2S + Mo + C, the obtained composite features abundant Mo nanocrystals embedded in crystalline Li2S matrices and then wrapped by few‐layer graphene. Notably, all three components derived from lithiothermic reaction are linked by the chemical bonding of MoS and CS, forming a compact Mo‐Li2S‐graphene triple heterostructure. Systematic studies reveal an unprecedented relevancy between charge overpotential and catalytic activation of Mo‐Li2S‐graphene, whereas a low activation potential of 2.43 V is achieved. Further studies disclose the relationship between cycle stability and confinement effect of core‐shell structure, whereas the improved confinement efficiency for polysulfides enables an excellent cycle life for the Li‐S battery. Moreover, the Mo‐Li2S‐graphene cathode demonstrates promising application for LIB, where the Mo‐Li2S‐graphene//SiC battery shows a high capacity of 764 mAh g−1 and outstanding cycle stability.