CoP@C with chemisorption-catalysis effect toward lithium polysulfides as multifunctional interlayer for high-performance lithium-sulfur batteries

Abstract

The development of the commercial lithium-sulfur (Li-S) batteries have been severely limited due to the disgusting shuttle effect and sluggish redox kinetics of lithium polysulfides (LiPSs) intermediates. Herein, cobalt phosphide (CoP) nanoparticles embedded into carbon spheres (CoP@C) as an interlayer on commercial polypropylene (PP) separator are designed through a facile co-precipitation method to address the above issues. The spherical CoP@C composite with numerous active sites can not only capture the LiPSs via strong chemical anchoring ability effectively, but also have good electrocatalytic ability to decrease the redox conversion barrier and enhance Li+ ion transport, ultimately promote the LiPSs conversion kinetics. Therefore, the Li-S batteries with CoP@C-PP separator show excellent electrochemical performance with high initial capacity of 1213 mAh g − 1 at 0.2 C, excellent cyclability with a low capacity fading rate of 0.058% per cycling upon long-term 800 cycles at 1.0 C, and a superior rate performance with 654 mAh g − 1 even at 5.0 C.