GO-CoNi alloy promotes internal reaction kinetics of lithium-sulfur batteries to improve long cycle performance at high-rate

Mitigating the shuttle reaction and facilitating catalytic conversion within the cell are the primary challenges to the development of high-performance lithium–sulfur batteries. To address these issues, a new type of composite material (GO-CoNi) was synthesized in this study. This material has excellent conductivity and rich active sites for polysulfide adsorption, thus improving the reaction kinetics within the cell. The GO-CoNi-coated separator exhibits an initial discharge capacity of up to 873 mAh/g in a long 2C cycle with a minor decay per cycle (0.04%) after 2000 cycles, and a decay of only 0.146% after 200 cycles in a high-rate 4C cycle. At a high sulfur loading (5.74 mg cm−2), the initial capacity is 962 mAh/g at a current density of 0.1 C, and the system remains stable for 100 cycles. Additionally, the performance of a battery using the GO-CoNi-coated separator is examined at high and low temperatures. At a high temperature of 60 °C, the first-cycle discharge is 1058 mAh/g, and after 100 cycles, the single-cycle decay is 0.417%. A capacity of 871 mAh/g can be realized on the first cycle at a low temperature of 2 °C; after 100 cycles, the single-cycle decays to 0.098%. Furthermore, in-situ Raman experiments provide insights into polysulfide adsorption by GO-CoNi-modified materials and the kinetics of the internal reaction of cells. Additionally, density functional theory confirms that modified materials exhibit strong polysulfide adsorption and promote the catalytic transformation of short-chain polysulfide into Li2S. This study provides a novel approach to promote the practical application of lithium-sulfur batteries, and demonstrates the feasibility of commercial applications through high-rate, high-sulfur loading, high-low temperature experiments.