Constructed conductive CoSe2 nanoarrays as efficient electrocatalyst for high-performance Li-S battery

Li-S battery has attracted great attention due to its high specific capacity and energy density. However, the serious polysulfides shuttle effect, low conductivity of sulfur and discharge product of lithium sulfide limit their application in commercial energy storage system. To solve the above problems, this work designs and constructs C@CoSe2 nanowire material as sulfur host for realizing high-performance Li-S battery. By combing the high conductivity, strong chemisorption, promising catalytic capacity and unique nanowire array structure, the C@CoSe2/S electrode demonstrates a high specific capacity of 1264 mAh.g(-1) with a low capacity decay of 0.051% per cycle at 0.2C over 200 cycles. As expected, the battery delivers outstanding capacity retention over 1000 cycles at 5C and the decay is as low as approximate to 0.026% per cycle. Moreover, even at higher sulfur loading of 5.1 mg.cm(-2), the battery could still remain a stable areal capacity of 5.02 mAh.cm(-2) at 0.2C. More importantly, the experimental data and theoretical calculation results reveal that the internal mechanism of the improved electrochemical performance is the catalytic activation of CoSe2 on polysulfides. Graphic abstract

Automated summary

The C@CoSe2/S electrode demonstrates a high specific capacity of 1264 mAh.g(-1) with a low capacity decay of 0.051% per cycle at 0.2C over 200 cycles, due to the high conductivity, strong chemisorption, promising catalytic capacity and unique nanowire array structure. The battery delivers outstanding capacity retention over 1000 cycles at 5C with a low decay rate of approximately 0.026% per cycle, showing stable areal capacity even at higher sulfur loading. The improved electrochemical performance can be attributed to the catalytic activation of CoSe2 on polysulfides, as revealed by experimental data and theoretical calculations.