Nickel-coordinated lignin enabled by nitrogen: A novel approach to high-performance carbon electrodes for supercapacitors

Lignin provides a new choice for supercapacitor electrode materials due to its high carbon content and abundant functional groups. The energy storage capacity of conventional lignin-derived electrode materials is frequently constrained by its architectures, resulting in characteristically diminished electrochemical efficacy. In this regard, we prepared hierarchical porous carbon (Ni@NLHPC) with the assistance of nitrogen atoms through the coordination of lignin with nickel. The coordination with lignin can effectively load nickel atoms onto the surface of carbon materials. The intense interaction between nitrogen and nickel effectively inhibits the excessive growth of nickel nanoclusters and improves their dispersion. The material demonstrates an impressive specific capacitance of 445.73F/g within the three-electrode system, showcasing its potential for high-performance supercapacitors. After the current density is increased by 40 times, the capacitance retention rate can reach 73.22 %. On this basis, we assembled a Ni@NLHPC/Ni@NLHPC symmetrical supercapacitor. The maximum energy density is 15.04 Wh/kg at a power density of 125 W/kg. After 10,000 constant current cycles, the capacitance retention rate is 75.91 %, which is a good prospect for application.