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 Ti3C2Tx 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.