Lignin-Based N-Carbon Dots Anchoring NiCoS/Graphene Hydrogel Exhibits Excellent Performance as Anodes for Hybrid Supercapacitor.

A NiCoS/N-CDs/RGO ternary composite hydrogel was prepared via a one-step hydrothermal method, utilizing lignin-based nitrogen-doped carbon dots as a bridge connecting NiCoS and graphene. The specific capacitance of NiCoS/N-CDs/RGO significantly outperforms that of the GH and NiCoS/RGO electrodes, achieving 1050 F g. The 3D mesh porous hydrogel structure mitigates NiCoS nanoparticle aggregation, providing a larger specific surface area for enhanced charge storage. The abundant functional groups of N-CDs interact with Ni (II) and Co (III) cations, favoring NiCoS particle synthesis. Additionally, an assembled solid-state asymmetric supercapacitor employing NiCoS/N-CDs/RGO as the positive electrode exhibited excellent energy density (68.4 Wh kg) and cycle stability (82% capacitance retention after 10,000 constant current charge-discharge cycles).