Developing a high-performance hybrid supercapacitor with the controlled assembly of a hierarchical 3D flower-like NiCo double hydroxide nano/microarchitecture electrode material

The design of hierarchical nano/microarchitectures containing multiple elemental compositions has attracted significant interest due to their ability to offer morphological, enhanced conductive, and exceptional electrochemical capabilities in the field of energy storage. Herein, a 3D flower-like porous nano/microarchitecture of NiCo double hydroxide (NCDH-1) was synthesized using a facile hydrothermal technique for supercapacitor electrode materials. The 3D hierarchical structure formed by the network arrangement of 2D nanosheets comprises of many open spaces between the nanosheets. These nanosheets lead to a large specific surface area, abundant active sites, and multiple channels for the transport of electrons/ions. These factors boost redox processes and facilitate the rapid transfer of electrons/ions into the electrode material. The NCDH-1 electrode material, with its hierarchical 3D nano/microarchitecture, exhibits the supreme capacitance (Csp) of 2199 F g⁻¹ at 1 A g⁻¹ and demonstrates excellent rate capability, retaining 58.2 % at 20 A g⁻¹. The hybrid supercapacitor configured using 3D flower-like NCDH-1 and commercial grade activated carbon (AC; MSP-20) electrodes demonstrates an impressive Csp of 232 F g⁻¹ at 1 A g⁻¹, a superior energy density of 72.5 Wh kg⁻¹, and an excellent cycle lifetime. Thus, the approach outlined in this work offers a promising strategy for developing 3D nano/microarchitecture metal hydroxides with potential applications in energy storage systems.