Local charge rearrangement to boost the chemical adsorption and catalytic conversion of polysulfides for high-performance lithium-sulfur batteries

摘要

Owing to their high energy density and low cost, lithium-sulfur (Li-S) batteries are deemed as promising next-generation energy-storage systems. However, the practical applications of Li-S batteries are still intercepted by the notorious shuttle effect and sluggish reaction kinetics. Herein, a porous nitrogen-doped carbon nanorod embedded with ultrafine Bi nanoparticles (Bi-NC) is constructed to function as an advanced sulfur host. The existence of Bi nanoparticles induces the local charge rearrangement and hence optimizes the electronic structure of Bi-NC. As a result, Bi-NC significantly features the effective chemical adsorption and remarkable redox catalyzation for polysulfides, corroborated by both computational and experimental demonstrations. Profiting from these distinctive superiorities, the enhanced utilization of sulfur species and facilitated redox kinetics of polysulfides are achieved. Therefore, the Bi-NC/S electrode delivers a high initial capacity of 1157 mA h g(-1) at 0.5C, a superb capacity retention of 811 mA h g(-1) at 1C after 500 cycles, and an excellent areal capacity of 6.48 mA h cm(-2) even under a high-sulfur loading of 7.0 mg cm(-2). This work affords an innovational regulation of electronic structures via the local charge rearrangement for developing ideal hosts towards the practical high-performance Li-S batteries.