In-situ adsorption and catalysis of polysulfide on Janus Ni3Fe−Fe2VO4 heterostructure for Li − S batteries

Abstract

The shuttling effect of lithium polysulfides (LiPSs) and the sluggish redox reaction of sulfur prevent the practical applications of lithium−sulfur (Li−S) batteries. Herein, a Janus Ni3Fe−Fe2VO4 heterostructure with a one-to-one butted configuration on carbon black (Ni3Fe−Fe2VO4/CB) is elaborately designed to realize the in-situ adsorption and catalysis of LiPSs. The special heterostructure shows a high concentration heterointerface and similar exposed surface area by optimizing the distribution and proportion of two kinds of active sites. Moreover, the covalent connection of Ni3Fe and Fe2VO4 phases produces electron redistribution in the heterostructure which further increases the chemisorption and catalytic ability of Fe2VO4 and Ni3Fe, respectively. It benefits the more efficient conversion for LiPSs. Battery with Ni3Fe−Fe2VO4/CB decorated separators remains 983.6 mAh g−1 after 500cycles at 0.2C, corresponding capacity decay rate of 0.028% per cycle, and high-rate capability of 877.5 mAh/g at 2.0C, which is 62.7% higher than battery with pristine polypropylene (PP) separators (539.5 mAh g−1). Even at the low E/S ratio (5 μL mg−1), it provides an excellent capacity decay rate of 0.038% per cycle over 500cycles, much lower than the pristine (0.109%). This work on heterostructure engineering offers an efficient spatial continuous reaction, which is valuable for integrating the adsorption and catalytic conversion processes for Li−S batteries.