Electrostatic Self-Assembly Mxene@Biomass Porous Carbon with Superior Cycle Stability for Lithium-Sulfur Batteries

Lithium-sulfur (Li–S) battery has high theoretical energy density and friendly environment, but its fast capacity attenuation limits its development. In this study, porous C was obtained by carbonization of the sycamore seed. The Ti3C2Tx@C composite material crosslinked network structure was constructed via electrostatic self-assembly method. Ti3C2Tx@C/S and C/S cathode materials were obtained by S loading of porous C and Ti3C2Tx@C composites via melting method. The composite materials were characterized by scanning electron microscopy, X-ray diffraction and thermogravimetry etc. Results showed that Ti3C2Tx@C composites have a porous structure and abundant active sites, which could effectively improve the physical and chemical adsorption capacity of S fixation (71 wt%) and polysulfide (PS), respectively. The C/S and Ti3C2Tx@C/S composites were used for battery assembly and electrochemical performance testing. Results showed that the initial discharge capacity of the Ti3C2Tx@C/S positive electrode at 0.1C was 1100 mAh/g, higher than the 930 mAh/g of the C/S. The Ti3C2Tx@C/S positive electrode still maintained a discharge capacity of 590 mAh/g after 400 cycles at 1C, and the capacity decay rate for each cycle was only 0.036%. The Ti3C2Tx@C/S composite with a unique structure and high S loading has broad application prospects in the field of Li–S batteries.