Cobalt phosphide embedded in a 3D carbon frame as a sulfur carrier for high-performance lithium-sulfur batteries

Abstract

• A porous three-dimensional carbon frame embedded with CoP nanoparticles (CoP@3DC) is synthesized. • CoP has a catalytic effect and can accelerate the conversion of LiPSs to inhibit the shuttle effect. • CoP@3DC/S delivers a superior discharge capacity of 640.6 mAh g −1 after 600 cycles at 1C. Lithium-sulfur (Li-S) batteries deliver a higher energy density than lithium ion batteries and are therefore regarded as next-generation batteries. However, the shuttle effect of soluble lithium polysulfides (LiPSs) and their slow redox kinetics are still the main setbacks for practical application. In this study, a porous three-dimensional carbon frame embedded with CoP nanoparticles (CoP@3DC) was synthesized by pyrolyzing and phosphating an acrylic cation exchange resin previously subjected to cobalt ion exchange. The abundant pores of CoP@3DC inhibit the diffusion of LiPSs, while its conductive three-dimensional carbon skeleton is conducive to the rapid transmission of electrons. In addition, CoP nanoparticles uniformly dispersed in the porous carbon network not only provide numerous chemical adsorption sites for LiPSs, but also accelerate their conversion to Li 2 S. Constant-current charging and discharging tests revealed that the CoP@3DC/S cathode achieves an initial discharge capacity of 1117.37 mAh∙g −1 at 0.5C and maintains a capacity of up to 740.56 mAh∙g −1 after 600 cycles, with a decay rate per cycle of only 0.056 %. Our work provides a facile supporting strategy for transition metal nanoparticles to significantly improve the performance of Li-S batteries.