Synthesis and interface construction of Fe0.5Co0.25Ni0.25S2 cathode material for high performance lithium-sulfur batteries

•A novel Fe0.5Co0.25Ni0.25S2 (FCN211) was rationally constructed.•Increasing the Fe content increased the anion redox capacity of FCN series materials.•The ion–electron dual-effect coating interface optimization strategy was proposed.•The cycle life of lithium-sulfur batteries was significantly improved. In lithium-sulfur batteries, carbon is commonly used as a host for sulfur in the cathode. However, carbon materials alone do not provide additional capacity and prevent the shuttle effect. This study aimed to create a novel material, Fe0.5Co0.25Ni0.25S2 (FCN211), by adjusting the molar ratios of Fe, Co and Ni. Analysis revealed that while the morphology of FCN-type materials remained consistent, there were notable differences in element distribution at the nanoscale. The modified FCN211@S/GC-CLCS cathode demonstrated a specific capacity of almost 1500mAh/g at 1 mA cm−2. Even with a sulfur content of approximately 6 mg cm−2, it maintained a specific capacity of 611mAh/g after 400 cycles at 1.5 mA cm−2. This study shows that by increasing the content of Fe element and adopting ion–electron dual-effect coating interface optimization, the anion redox capacity of FCN material in lithium-sulfur batteries can be further utilized.