Accelerating catalytic conversion and chemisorption of polysulfides for advanced Li-S batteries from incorporating FeNi@CoN hetero-nanocrystals into boron carbonitride nanotubes.

With the rapid development of large-scale clean energy, lithium-sulfur (Li-S) batteries are considered to be one of the most promising energy storage devices. In this manuscript, the polymetallic hetero-nanocrystal of iron nickel@cobalt nitride encapsulating into boron carbonitride nanotubes (FeNi@CoN@BCN) was designed and optimized for use as a modified material for commercial polypropylene (PP) separators. The prepared FeNi@CoN@BCN-12 hybrid material presents strong chemisorption and catalytic conversion capabilities, which endows the FeNi@CoN@BCN-12//PP separator with enhanced polysulfide shuttling inhibition. The assembled Li-S cells with FeNi@CoN@BCN-12//PP separators have minimized charge transfer resistance and faster redox kinetics. Additionally, cells with FeNi@CoN@BCN-12//PP separator provide high reversible capacity of 674 mAh/g for 400 cycles at 0.5C and excellent cyclability for 1000 cycles at 2C with a low decay rate of 0.05 % per cycle. Therefore, this study provides a feasible functionalization route for improving the electrochemical performance of Li-S batteries through separator modification.