Handy preparation of a carbon-Ni/NiO/Ni(OH)2 composite and its application in high-performance supercapacitors

The growing demand for energy storage is required with the development of the intermittent renewable energy. Supercapacitors are a promising energy storage equipment, but their capacitive performance mainly depend on the electrode material. To obtain a high-performance electrode material for supercapacitors, in this work, a carbon-Ni/NiO/Ni(OH)₂ composite was prepared from pine sawdust as the carbon precursor by integrating CO₂ gasification and electrochemical deposition. It is found that the carbon-ternary nickel composite shows good electrochemical performance due to synergistic effect of the unique hierarchical structure and components involving porous carbon skeleton, Ni⁰ and NiO nanoparticles, and Ni(OH)₂ microspheres. The composite displays the specific capacitance of 1875.6 F/g (or 937.8 C/g) at a current density of 1 A/g in a traditional three-electrode system. The assembled asymmetric supercapacitor device presents a potential window of 1.6 V, along with the energy density of 38.24 Wh/kg at the power density of 400 W/kg (or 22.60 Wh/kg at 2000 W/kg). After 6000 charge-discharge cycles, the capacitance retention ratio of the assembled supercapacitor reaches up to 105 %, exhibiting a good application potential. This work provides a novel and handy strategy for preparation of ternary nickel-based composite for advanced supercapacitors.