Modifying γ-MnO₂ to enhance the electrochemical performance of lithium-sulfur batteries

The practical application of high energy density and cost-effective lithium-sulfur batteries is still impeded by such factors as insulation nature of sulfur/lithium sulfides and poor cycling lifespan. Here, an integrated sulfur-containing cathode (S cathode) with modified γ-MnO₂ as the sulfur host is fabricated to address the capacity decline during cycling. When coupled with pre-lithiation and molybdenum doping, the electronic and ionic conductivity of the modified γ-MnO₂ host is enhanced, which reduces the cycling voltage hysteresis of the S cathode. The modified γ-MnO₂ shows strong chemisorption with the intermediate polysulfides that are generated unavoidably during lithium ions intercalation/deintercalation of a S cathode, and presents role of electrochemical catalysis for discharge/charge process to accelerate the redox kinetics of the polysulfides. Consequently, the prepared S cathode demonstrates highly enhanced performance, with an initial specific capacity of 1441 mAh g⁻¹ at a rate of 0.1C, and a maximum areal capacity of 5.37 mAh cm⁻² with sulfur loading of 5.8 mg cm⁻². The cycling stability is superior with a capacity retention of 617.2 mAh g⁻¹ at 2C after 500 cycles, and good rate capability is also achieved. This S cathode offers a potential alternative for high-performance lithium-sulfur batteries.