One‐Step Synthesis of NiCo‐LDH@Ni(OH)₂ Heterostructure Foams on Biomass‐Derived Porous Carbon for High‐Performance Supercapacitors

Layered double hydroxides (LDHs) have attracted much attention as pseudocapacitor supercapacitor electrodes because of their high theoretical specific capacity. However, LDHs have drawbacks such as poor electrical conductivity, and their specific capacities are lower than the theoretical values. In this work, NNCLDH@OPC electrodes are constructed via in situ synthesis of heterostructure foams (NNCLDH) consisting of NiCo-LDH and Ni(OH)₂ on pomelo peel-derived porous carbon (OPC) through a one-step solvothermal method using ZIF-67 as a template. Owing to the synergistic effect of the 3D nanofoam structure and the multicomponent heterostructure as well as the conductive porous carbon support, the NNCLDH/OPC exhibited ultrahigh electrochemical performance as well as excellent cycling stability: a specific capacity of 3290 F g^-1 at 1 A g^-1 and a capacitance retention of 77.8% after 4000 cycles at a current density of 10 A g^-1. In addition, the assembled NNCLDH@OPC//OPC asymmetric supercapacitor (ASC) has a maximum energy density of 51 Wh kg^-1 with a power density of 812 W kg^-1 and a maximum power density of 16 kW kg^-1 at a current density of 20 A g^-1. These results demonstrate the significant application potential of NNCLDH/OPC composites in supercapacitor electrodes.