Cobalt nanoparticles embedded hollow phosphorus and nitrogen co-doped carbon nanocages accelerate polysulfides conversion for lithium-sulfur batteries

Abstract

Lithium-sulfur (Li-S) batteries suffer from sluggish redox reaction kinetics and inevitable shuttle effect of lithium polysulfides (LiPSs), which severely impede their commercial application. Herein, the porous P, N-doped carbon nanocages with uniformly embedded Co nanoparticles (Co@PNC) are well-designed to serve as an effective host catalyst for Li-S batteries. Doped P-atoms can effectively regulate the electronic metal-support interaction between Co nanoparticles and N-doped carbon frameworks, which modifies the energy band structure and induces more active electronic states. Co@PNC can simultaneously provide strong adsorption capacity and high catalytic conversion efficiency of LiPSs, as well as accelerate Li₂S nucleation/decomposition kinetics during the charge and discharge processes. Consequently, the assembled Li-S battery achieves superior rate capability and stable cycle performance with a capacity decay of only 0.033 % per cycle over 1000 cycles. Notably, Co@PNC/S electrodes deliver a high specific capacity of 766.8 mAh g^-1 after 100 cycles even under high sulfur loading of 4.46 mg cm^-2 and poor electrolytes.