3D Carbon/Cobalt‐Nickel Mixed‐Oxide Hybrid Nanostructured Arrays for Asymmetric Supercapacitors

The electrochemical performance of supercapacitors relies not only on the exploitation of high‐capacity active materials, but also on the rational design of superior electrode architectures. Herein, a novel supercapacitor electrode comprising 3D hierarchical mixed‐oxide nanostructured arrays (NAs) of C/CoNi 3 O 4 is reported. The network‐like C/CoNi 3 O 4 NAs exhibit a relatively high specific surface area; it is fabricated from ultra‐robust Co‐Ni hydroxide carbonate precursors through glucose‐coating and calcination processes. Thanks to their interconnected three‐dimensionally arrayed architecture and mesoporous nature, the C/CoNi 3 O 4 NA electrode exhibits a large specific capacitance of 1299 F/g and a superior rate performance, demonstrating 78% capacity retention even when the discharge current jumps by 100 times. An optimized asymmetric supercapacitor with the C/CoNi 3 O 4 NAs as the positive electrode is fabricated. This asymmetric supercapacitor can reversibly cycle at a high potential of 1.8 V, showing excellent cycling durability and also enabling a remarkable power density of ∼13 kW/kg with a high energy density of ∼19.2 W·h/kg. Two such supercapacitors linked in series can simultaneously power four distinct light‐emitting diode indicators; they can also drive the motor of remote‐controlled model planes. This work not only presents the potential of C/CoNi 3 O 4 NAs in thin‐film supercapacitor applications, but it also demonstrates the superiority of electrodes with such a 3D hierarchical architecture.