P-doped NiSe2 nanorods grown on activated carbon cloths for high-loading lithium-sulfur batteries

Abstract

Although lithium-sulfur batteries have drawn widespread attentions due to their high energy densities at low costs, the scale-up applications are still hindered by issues such as dissolution of lithium polysulfides (LiPSs) and slow oxidation/reduction kinetics. Herein, we report a novel cathode composite composed of “moss-like” P-doped NiSe2 arrays grown on activated carbon cloth substrates (P-NiSe2/ACC). Experiments and DFT calculations together suggest that P-doping enhances the electron transfers between P-NiSe2 and LiPSs, leading to improved chemical adsorptions and catalytic effects towards the redox conversions of the active sulfur species. This effectively inhibits the shuttling of LiPSs and maximizes the utilization of sulfur towards high specific capacities and stable long-term cycling at high sulfur loadings. The strong interactions and effective catalysis of P-NiSe2 on LiPSs also enables three-dimensional growth of Li2S2/Li2S on the P-NiSe2/ACC cathode, realizing effective accommodation of volume expansions and significant alleviation of cathode passivation. As a result, the P-NiSe2/ACC cathode provides a high specific capacity of 1211 mAh g−1 at 0.2 C and an outstanding high-rate performance of 679 mAh g−1 at 3 C. At the high sulfur loading of 9.9 mg cm−2, an area capacity of 8.42 mAh cm−2 is achieved with stable cycling for 100 charge/discharge cycles.