Nanoflower-like Nickel–Cobalt Bimetallic Hydroxide Electrode Materials for Asymmetric Supercapacitor

Using the electrodeposition approach, nanoflower nickel–cobalt bimetallic hydroxide (NiCoLDH) was synthesized in situ on nickel foam substrate as supercapacitor electrode material. The impacts of surfactant pretreatments on the morphology and electrochemical characteristics of LDH-based materials were examined. When poly(vinylpyrrolidone) (PVP) is applied as a pretreatment for NiCoLDH, it facilitates the formation of densely grown nanoflowers and a three-dimensional conductive network. This development significantly enhances the interaction between the electrode and the electrolyte, promoting an improved electrochemical performance. PVP adsorbed on the surface of nickel foam can further increase the loading of the electrode materials on nickel foam during the electrodeposition process. Consequently, NiCoLDH-PVP has a specific capacitance of 6.35 F cm–2 at 1 mA cm–2. The assembled NiCoLDH-PVP//AC asymmetric supercapacitor can reach an energy density of 741 μWh cm–2 at a power density of 800 μW cm–2. The modification provides an approach and guides the simple and efficient synthesis of high-performance layered double hydroxides.