Graphene Modified NiCo-LDH and 3D CNTs@rGO Carbon Hydrogel for High-Performance Asymmetric Supercapacitor

Abstract Considering the distinct charge storage mechanisms, it is difficult to achieve high energy density while maintaining high power density in electric double-layer capacitors (EDLCs) and pseudocapacitors. Therefore, it is necessary to rationally design the structure of electrode materials to balance these properties. In this work, a positive electrode material is designed based on reduced graphene oxide-coated NiCo layered double hydroxide (NiCo-LDH@rGO), which exhibits high specific capacity (218.64 mAh g−1) and favorable rate capability. Notably, this work features the rational design of both electrodes: the rGO coating on NiCo-LDH enhances interfacial conductivity and structural stability, while the negative electrode is constructed as a CNT/rGO hybrid carbon hydrogel, where one-dimensional CNTs serve as both physical spacers to prevent rGO restacking and conductive bridges to construct a three-dimensional hierarchical conductive network. Consequently, the negative electrode material demonstrates exceptional cycling stability. The asymmetric supercapacitor assembled using NiCo-LDH@rGO and 5CNTs@rGO achieved an energy density of 56.30 Wh kg−1 at a power density of 108.26 W kg−1.