Redox active coating on graphite surface of hierarchically porous wood electrodes for supercapacitor application

A free-standing electrode with hierarchical pores and graphite surface is derived from wood pellet via a catalytic graphitization. The aligned microchannels of natural wood and the high conductivity of graphite has enabled fast ionic and electronic transport. The high porosity leads to a large surface area for the deposition of redox active materials. After an electrodeposition of Ni(OH)2 and Co(OH)2 on the graphitized wood, the electrode exhibits a high areal capacity without significant degradation in the electrochemical performance. An asymmetric supercapacitor, with a graphitized wood as the negative electrode and a Ni(OH)2/Co(OH)2 deposited wood as the positive electrode, shows a high areal capacitance of 2 409 m F/cm2, a high energy density of 0.75 mWh/cm2 at a power density of 0.750 mW/cm2. This high performance, free-standing and biodegradable wood-derived asymmetric supercapacitor demonstrates promising applications as energy storage devices.