Insights into nickel nanoparticles modified porous biomass-derived carbon as sulfur host matrix for advanced rechargeable lithium-sulfur battery

Abstract

Lithium-sulfur (Li-S) batteries are regarded as promising high energy density energy storage devices, but their commercial applications are limited due to the poor conductivity of sulfur and the harsh shuttle effect of lithium polysulfides (LiPSs). Herein, nickel-embedded porous carbon materials (Ni/PC) with high electrical conductivity, abundant pores and large space for storage of sulfur were synthesized by instantaneous expansion, nickel salt treatment and high-temperature calcination using corn kernels as precursors. According to the electrochemical results of the designed sulfur-carbon (S@Ni/PC) composite cathode, it delivers a high initial capacity of 1100 mAh·g−1 at 0.5 C as well as maintaining a capacity of 579.3 mAh·g−1 after 500 cycles with coulombic efficiency close to 100%, while the pure sulfur cathode can only remain 143.9 mAh·g−1. Furthermore, the rate performance test displays that a high reversible capacity of 1189 mAh·g−1 can still be maintained when returning to 0.1 C after different current densities, which is nearly 643.5 mAh·g−1 higher than the PC cathode. Such excellent electrochemical performance benefits from the synergistic effect of the interconnected porous structure and polar Ni nanoparticles (NPs). On the one hand, porous carbon materials provide large space for efficiently immobilizing sulfur, and the staggered pores physically hinder the diffusion of lithium polysulfides (LiPSs). On the other hand, in-situ intercalated Ni NPs can both improve electrical conductivity and afford abundant adsorption sites for chemically anchoring LiPSs to suppress shuttle effect. This work reports a facile and useful strategy for the application of biomass carbon in Li-S batteries.