Biosorption-Directed Integration of Hierarchical CoO/C Composite with Nickel Foam for High-performance Supercapacitor

Attributed to the low cost, chemical stability and high theoretical specific capacitance, cobalt monoxide (CoO) is a superior material for electrodes in supercapacitor. Here, we propose the nickel foam supported Chlorella-inspired CoO/C hierarchical structure for the making of a binder-free electrode for supercapacitor application. The fabrication process takes advantage of the Chlorella's biosorption. The fabricated structure shows excellent electrochemical properties with a specific capacitance of 648 F/g (at current density of 0.5 A/g), and good cycling stability (no diminution over ∼8000 cycles at the current density of 3 A/g). The asymmetric supercapacitor device is assembled by employing CoO/C composite as the positive electrode and activated carbon as the negative electrode. Such device delivers a high energy density of 30.9 Wh/kg at 398 W/kg, and a maximum power density of 8000 W/kg. This work demonstrates a low-cost bio-inspired method of producing CoO/C composite, which can be used as an active electrode for electrochemical supercapacitors.