Vertically porous nickel thin film supported Mn₃O₄ for enhanced energy storage performance

Three-dimensionally porous metal materials are often used as the current collectors and support for the active materials of supercapacitors. However, the applications of vertically porous metal materials in supercapacitors are rarely reported, and the effect of vertically porous metal materials on the energy storage performance of supported metal oxides is not explored. To this end, the Mn₃O₄-vertically porous nickel (VPN) electrodes are fabricated via a template-free method. The Mn₃O₄-VPN electrode shows much higher volumetric specific capacitances than that of flat nickel film supported Mn₃O₄ with the same loading under the same measurement conditions. The volumetric specific capacitance of the vertically porous nickel supported Mn₃O₄ electrode can reach 533 F cm⁻³ at the scan rate of 2 mV s⁻¹. The fabricated flexible all-solid microsupercapacitor based on the interdigital Mn₃O₄-VPN electrode has a volumetric specific capacitance of 110 F cm⁻³ at the current density of 20 μA cm⁻². The capacitance retention rate of this microsupercapacitor reaches 95% after 5000 cycles under the current density of 20 μA cm⁻². The vertical pores in the nickel electrode not only fit the micro/nanofabrication process of the Mn₃O₄-VPN electrode, but also play an important role in enhancing the capacitive performances of supported Mn₃O₄ particles.