关键词: 锂硫电池, 隔膜改性, 双金属有机框架, 穿梭效应

Abstract:

The commercial application of lithium-sulfur batteries (LSB) is still limited by the irreversible capacity fading caused by the shuttle of lithium polysulfides (LIPS). To address this issue, a bimetal (nickel, cobalt)-organic framework (MOF) derived carbon, (Ni, Co)/C, was prepared to modify the separator. The multifunctionally modified separator effectively captures LIPS, ensuring the stability and reversibility of sulfur fixation, while providing catalytic activity and improving ionic conductivity. The cobalt metal has a larger coordination number, more pore structure distribution, larger specific surface area, more surface C=O, and smaller particle size to achieve a large and rapid chemical sulfur fixation. The high conductivity provided by nickel, and the catalytic activity and the ability to block LIPS shuttling enabled the reversibility of sulfur inhibition. The synergistic effect of cobalt-nickel bimetals significantly improves the cycling stability and rate capability of LSB. At a current density of 1 C, the capacity of the (Ni, Co)/C modified separator battery could reach 1035.6 mAh·g^-1 in the first cycle, the capacity remained at 662.2 mAh·g^-1 after 500 cycles, and the capacity retention rate was 63.9%.

Key words: Lithium-sulfur battery, Modified separator, Bimetal-organic framework derived carbon composites, Shuttle effect