Synergistic sulfur-selenium cathodes for lithium-sulfur batteries

Lithium-sulfur batteries are promising for next-generation energy storage but face challenges such as the polysulfide shuttle effect, slow kinetics, and lithium dendrite growth. Here we report a novel approach utilizing two-dimensional carbon nanosheets for the encapsulation of sulfur and selenium materials. Furthermore, we employed a high-temperature selenization process to facilitate the ingress of a larger number of Se atoms into the mesopores and macropores of the two-dimensional carbon nanosheets, thereby providing comprehensive protection for Se within the carbon nanosheets. The cathode exhibits a high initial capacity of 1418 mAh/g at 0.1 C and low-capacity decay rates of 0.11 % for 500 cycles at 1 C, and 0.101 % for 400 cycles at 2 C, respectively. X-ray photoelectron spectroscopy (XPS) and Density functional theory calculations (DFT) show that there is a strong adsorption effect between sulfur, selenium and the substrate material, which can inhibit the generation of shuttle effects. Our work provides a scalable and viable strategy for long-term lithium storage applications.