Ultrathin Ni-doped MoS₂ film operando depositing on sulfur/carbon cathode to enhance the redox kinetics in room-temperature Na–S batteries

Room-temperature sodium-sulfur (RT Na-S) batteries have become a strong contender in energy storage owing to their ultra-high energy density and low costs. Whereas, the practical application of RT Na-S batteries is limited by issues such as sluggish redox reactions and shuttle effects in sulfur (S) cathodes. To solve these challenges, this study introduces a novel Ni-doped MoS₂/MPC/S cathode material for RT Na-S batteries, in-situ synthesized via magnetron sputtering. Compared with single MoS₂ film, the introduction of Ni atoms endows the film with superb chemisorption capacity and catalytic performance for polysulfides. Meanwhile, the bio-derived porous carbon raises the electroconductivity of the sulfur cathodes and mitigates volume changes during cycling. Assembled with this as-prepared cathode, the RT Na-S batteries display remarkable specific capacity (1070.56 mAh g⁻¹, 100 cycles at 0.1 A g⁻¹) and splendid rate performance (557.24 mAh g⁻¹, 400 cycles at 2 A g⁻¹, and 467.49 mAh g⁻¹, 500 cycles at 3 A g⁻¹). The superior electrochemical performance is ascribed to the rapid polysulfides conversion catalyzed by Ni-MoS₂ microspheres, as further supported by the density functional theory (DFT) calculations. The present work provides new insights into designing highly efficient catalysts with heterogeneous doping for high-performance RT Na-S batteries.