Two-Dimensional Layered MXene-Supported NiS2 Composite Electrode Material for High-Performance Supercapacitors

MXene, a unique two-dimensional material, has shown great application potential in supercapacitors. However, MXenes are prone to oxidation and self-stacking, which affect their conductivity and chemical properties. In this paper, combining the hydrothermal method and high-temperature vulcanization, we assembled composite materials consisting of NiS2 nanosheets on Ti3C2T x MXene, where NiS2 nanosheets are not plain lamellar structures but formed granular nanosheets. Owing to the specific structure between MXene and NiS2 nanosheets, the as-prepared nanomaterials possess more surface sites and enhance the transport of ions and electrons in oxidation-reduction reactions. Simultaneously, as a cathode material for supercapacitors, NiS2/MXene can provide a specific capacitance of 580 C g-1 at the current density of 1 A g-1. The assembled NiS2/MXene||AC hybrid capacitor achieves a higher energy density of 34.53 W h kg-1 at the power density of 910.68 W kg-1, nearly 10 more than that of the NiS2. After 4000 cycles, it can still maintain a capacity of 85.21%, and the Coulomb efficiency can reach 98.13%, which is significantly higher than that of MXene and NiS2. The above results show that NiS2/MXene composites hold promise for applications in energy storage.