Hierarchical Ni-doped ZCOH electrodes with morphology-driven performance in asymmetric supercapacitors

The escalating demand for advanced energy storage solutions has catalyzed an intensified inquiry into high-performance electroactive materials, with metal oxide hybrids garnering significant interest for applications in supercapacitors. In the present investigation, nickel-doped zinc-cobalt hydroxide (Ni-ZCOH) electrodes were systematically synthesized by hydrothermal method to clarify the impact of nickel integration on structural evolution, morphological characteristics, and electrochemical efficacy. Incremental nickel doping leads to substantial phase modulation and morphological alteration, culminating in augmented surface porosity, an excess of electroactive sites, and enhanced kinetics of ion transport. The optimally doped 05-Ni-ZCOH electrode exhibits high electrochemical performance, delivering a specific capacitance (C_s) of 670 F/g, a specific capacity (C_c) of 402C/g, an areal capacitance of 6.77 F/cm2, and a volumetric capacitance of 41.87 F/cm3 at a current density of 5 mA/cm2. Moreover, hybrid aqueous supercapacitor device (HASCD) demonstrates excellent electrochemical performance, delivering a high specific capacitance of 31.89 F/g at a current density of 5 mA/cm2, along with a notable energy density of 14.35 Wh/kg at a corresponding power density of 555 W/kg. The HASCD demonstrates excellent cycling stability, maintaining 53% of its original capacity even after 14k charge-discharge cycles, while sustaining a coulombic efficiency of nearly 119%. These findings underscore the suitability of ZnCo₂OH₄//AC as a high-performance electrode material, as it integrates high capacitance with robust cycling durability and outstanding rate capability, making it a strong candidate for next-generation energy storage systems.