Niobium Phosphide-Induced Sulfur Cathode Interface with Fast Lithium-Ion Flux Enables Highly Stable Lithium-Sulfur Catalytic Conversion.

Abstract

Research on the Li-S catalytic chemistry primarily focus on the development of high-performance catalysts and the exploration of their reaction mechanisms, with limited attention given to the impact on the interface at the cathode. Moreover, regulating the Li+ flux at the cathode interface can enhance Li2S conversion kinetics without compromising the intrinsic catalytic activity of catalyst. This work presents a paradigm that employs interface regulation to enhance Li-S battery cycling stability. A novel phosphorus doped carbon supported niobium phosphide nanocrystals (NbP/PC) catalyst is developed and demonstrates exceptional intrinsic activity for lithium polysulfide conversion while it facilitates lithium salt dissociation through intermolecular hybridization. The NbP-induced functional interface layer with abundant LiF and Li3N provides efficient Li+ transport channel for Li2S decomposition, which further mitigates the passivation of active sites. In consequence, the assembled Li-S batteries (LSBs) exhibit a capacity retention rate of 0.04% per cycle after 1100 cycles at a 1 C. Furthermore, the pouch batteries with an energy density of 451 Wh kg-1 maintain stable performance over 20 cycles. This strategy addresses the limitations of traditional catalytic material design in the chemical regulation of the cathodic interface for promising future of LSBs.