Ni-NiS Heterojunction Composite-Coated Separator for High-Performance Lithium Sulfur Battery

Abstract

The shuttle effect and slow REDOX kinetics of lithium polysulfides (LiPSs) lead to low sulfur utilization rate, short cycle life, poor rate performance, which hinder the application of Li–S batteries. Herein, the Ni-NiS/NCF heterojunction composite was prepared with multistage pore structure and a large specific surface area, which can effectively capture LiPSs, provide more active sites for catalyzing LiPSs. Moreover, due to the heterojunction structure of Ni-NiS, in which NiS can effectively capture and catalyze lithium polysulfide, and Ni can effectively accelerate the diffusion and charge transfer of lithium ions, the Ni-NiS/NCF heterojunction composite establishes a high ion and electron conduction network, so as to achieve efficient mass and charge transfer capacity. The mutual coordination of uniformly distributed Ni-NiS heterojunctions inhibits the shuttle effect of LiPSs. When the sulfur load is 1.8 mg/cm2, the initial capacity of the cell with Ni-NiS/NCF-coated separator at 1 C is 1109.6 mAh/g, and the final discharge capacity is maintained at 618.0 mAh/g after 300 cycles. At the same time, the reversible specific capacity was maintained at 674.0 mAh/g after 50 cycles even under high sulfur load.