Preparation and electrochemical properties of MXene/NiS2 nanocomposites

MXene/NiS 2 composite was synthesized by one-step hydrothermal method with nickel nitrate and thiourea as raw materials and MXene as substrate. The nanosheets connected in the composite exhibit a void network structure, which favors ion and charge transfer. The results show that the electrochemical properties of the composite were optimized (maximum specific capacitance = 898.2 F·g − 1 ) at synthesis temperature of 180 ℃ and Ni/S ratio of 1:2. Compared with pure MXene (157.4 F·g − 1 ) and pure NiS 2 (616 F·g − 1 ), the MXene/NiS 2 -1:2-180 composites exhibited superior properties. The asymmetric supercapacitor was assembled in 6 M KOH with MXene/NiS 2 as anode and SC (biochar) as cathode. High energy density (32.08 Wh·kg − 1 ) and power density (749.92 W·kg − 1 ) can be obtained at an operating voltage window of 1.5 V. After 3000 charging/discharging cycles at 2 A·g − 1 , the specific capacitance was 85.74% of the original specific capacitance.