Nickel-cobalt (oxy)hydroxide battery-type supercapacitor electrode with high mass loading

Transition metal hydroxides have shown high capacity performances when at a small mass loading of active material, while it is still a great challenge to obtain a high capacity performance when the mass loading is high. To maximize the capacity at high mass loading, the microstructure of the electrode should be rationally designed. Herein, we report a nickel-cobalt (oxy)hydroxide composite with three-dimensional hierarchical porous architecture realized by an in-situ electrochemical activation method to trigger the active sites and structural rearrangement. By systematically tuning the pore sizes in the hierarchical structure, an optimal composite delivers a record high areal capacity (34.8 mAh cm-2) and energy density (19.1 mWh cm-2) at the mass loading up to 230 mg cm-2. It gives new insights for preparing high performance electrode materials by a facile method and provides a blueprint for the design of high mass-loading supercapacitors.

Automated summary

Transition metal hydroxides exhibit high capacity performance at low mass loading but face challenges at high mass loading. A nickel-cobalt (oxy)hydroxide composite with hierarchical porous architecture was developed to achieve record high areal capacity and energy density at a mass loading up to 230 mg cm-2. This study provides insights into preparing high-performance electrode materials and designing high mass-loading supercapacitors.