Sulfur-doped hollow C@CoP nanosphere modified separator for enhancing polysulfides anchoring and conversion in Li-S batteries

Lithium-sulfur (Li-S) battery with high theoretical energy density is recognized as a promising energy storage device, while its commercial applications are still hampered by the severe shuttling effect and sluggish kinetics of lithium polysulfides (LiPSs). Heteroatoms doping, which can adjust the electronic configuration and regulate the adsorption and catalytic properties, is realized as an effective strategy to solve the above problems. Herein, sulfur-doped CoP nanoparticles embedded in hollow carbon microspheres (C@S-CoP) is designed and employed as the modification material for separator. The introduction of sulfur atom into CoP leads to enhanced chemi-sorption for LiPSs and favorable conversion kinetics of sulfur species. In addition, the hollow porous structure of C@S-CoP is beneficial to the penetration of electrolyte and the alleviation of the sulfur species expansion during cycles. Theoretical calculation is further utilized to elucidate the enhanced mechanisms of S-CoP in Li-S chemistry at molecular level. The cell with C@S-CoP-separator delivers a superior rate performance of 761 mAh g-1 at 5C and excellent cyclability over 400 cycles at 2C with a low-capacity decay rate of 0.060%. This work furnishes a feasible strategy to boost the electrochemical performance and promotes the development of func-tional separators for highly efficient Li-S battery.

Automated summary

In this study, sulfur-doped CoP nanoparticles embedded in hollow carbon microspheres (C@S-CoP) were designed and used as modification material for the separator in lithium-sulfur (Li-S) batteries. The introduction of sulfur atoms enhanced chemi-sorption for lithium polysulfides (LiPSs) and improved the conversion kinetics of sulfur species. The hollow porous structure of C@S-CoP facilitated electrolyte penetration and alleviated the expansion of sulfur species during cycling. The experimental results showed that the Li-S battery with C@S-CoP separator exhibited superior rate performance and excellent cyclability.