Co-Ni Bimetallic Sulfides Functionalized Interlayer with Efficient Catalytic Conversion for Li-S Batteries

Abstract

: Tardive practical development of lithium-sulfur (Li-S) batteries faces two fatal nuisances, the grievous shuttle effect of sulfur electrodes as well as rock-ribbed Li dendrites, which results in undesired cycling lifespan and the potential safety hazard. Diversified electrocatalytic materials are employed to enhance polysulfides conversion kinetics and subsequently restrain shuttle effect. Here, pyrite-type cation regulation strategy is applied to motivate the electrochemical catalysis capability of bimetallic sulfide by regulating the cation ratio of Co and Ni ions. The reformative bimetallic sulfide with Co to Ni ratio near 2:1 shows stronger chemical adsorption capability towards lithium polysulfides in contrast to pristine NiS 2 , which resulted from the strong contribution of metal oxide layer. The comparable electrochemical kinetics and electrochemical performances of Li-S batteries with CNS-2/CP interlayer show in the aspects of low polarization voltage, high lithium ion diffusion rate, high discharge capacity, as well as better rate performances. These results demonstrate cation regulation could be an efficient strategy for material design to optimize the surface physicochemical properties of iron pyrite for boosting the cycle durability of Li-S batteries