Two-dimensional layered Co₃O₄/CoSe₂ heterostructure modified separator for high-capacity and long-cycle...

Lithium-sulfur (Li-S) batteries are promising for energy storage due to their high theoretical energy density and specific capacity. However, the polysulfide shuttle effect severely limits their performance. In this study, two-dimensional (2D) Co₃O₄/CoSe₂ heterostructures were synthesized to enhance polysulfide adsorption and catalysis through synergistic effects. The Co₃O₄/CoSe₂ heterostructure exhibited strong adsorption and catalytic activity, significantly improving the battery's reaction kinetics. At a 1 C rate, the initial discharge capacity reached 958.22 mAh g^-1, with a capacity decay rate of only 0.04 % per cycle over 2000 cycles. At a 2 C rate, the initial capacity was 909.89 mAh g^-1, with a decay rate of 0.06 % over 1400 cycles. Under high temperature conditions (60 °C), the battery delivered an initial capacity of 990.47 mAh g^-1, with a single-cycle decay rate of 0.1 % after 200 cycles. At a low temperature (10 °C), the initial capacity was 1039.1 mAh g^-1, with a decay rate of 0.1 % per cycle after 200 cycles. Additionally, with a high sulfur loading of 3.54 mg cm^-2, the initial capacity reached 1041.8 mAh g^-1, retaining 385.96 mAh g^-1 after 200 cycles. These results demonstrate the effectiveness of the Co₃O₄/CoSe₂ heterostructure in mitigating the polysulfide shuttle effect and improving the performance of Li-S batteries, offering new opportunities for advanced energy storage systems.