Electrodeposition preparation of NiCo₂O₄ mesoporous film on ultrafine nickel wire for flexible asymmetric supercapacitors

Mesoporous NiCo₂O₄ was directly coated on an ultrafine nickel wire to fabricate a battery-type electrode through a facile process comprising electrodeposition of Ni/Co/Zn alloy, dealloying, and oxidation. The binder-free electrode with flexible features delivers a high specific capacity of 315.4 C g⁻¹ and excellent cycling performance (retention after 50,000 cycles). An assembled asymmetric supercapacitor containing NiCo₂O₄/ultrafine nickel wire with Fe₃O₄/ultrafine nickel wire shows high energy density of 32.6 Wh kg⁻¹, high power density of 35,000 W kg⁻¹, and 94.8% retention of initial capacity after 20,000 cycles. This work proposes a simple design and facile process for fabrication of practical flexible energy storage devices.