Highly porous nickel cobaltite film composed of nanosheets with attached nanowires as an electrode material for electrochemical capacitors

Nickel cobaltite hetero-nanostructure with superior capacitive behavior is grown on stainless steel mesh by one-pot hydrothermal synthesis at slow cooling rate. Porous nickel cobaltite film composed of nanosheets with attached nanowires (NS-NW) provides numerous pore channels for fast transport of electrolyte, large surface area for reversible Faradaic reaction, and short diffusion pathways in solid phase. The specific capacitance of NS-NW reaches 775 F g−1 at 5 A g−1, which is higher than that of nanosheet (435 F g−1). Porous film with nanosheet and nanowire configuration exhibits low charge-transfer resistance, diffusive impedance, and volumetric strain, leading to high specific capacitance, rate performance, and cycle-life stability.