A carbon sponge supporting a MoS₂-Mo₂C heterostructure as the Li₂S host for high-performance lithium sulfur batteries

Despite their high theoretical capacity and energy density, lithium-sulfur (Li–S) batteries still face challenges such as soluble lithium polysulfides (LiPSs) shuttling and sluggish redox kinetics. In this work, we used a novel MoS2-Mo2C heterostructure anchored on a carbon sponge (CS) as a Li2S host to solve these problems. A simple hydrothermal process following carbothermal reduction was used to construct the MoS2-Mo2C heterostructure, enabling control of the phases and integration of MoS2 and Mo2C. Structural characterization confirmed the coherent interface of the heterostructure with a precise orientation relationship between the two phases and their uniform distribution. An evaluation of the adsorption and catalytic performance of the material showed that it has an exceptional LiPSs adsorption capacity with faster conversion from Li2S4 to Li2S2. Density functional theory calculations further confirmed these results. As a result, the cathode had a high initial discharge capacity of 693 mAh g−1 at 0.2 C and achieved stable cycling at 2 C for 500 cycles with a low decay rate of 0.107% per cycle. The heterostructure design, coupled with the macroporous CS framework, effectively prevented the shuttling and increased sulfur utilization, offering a promising way to produce practical high-energy-density Li–S batteries.