High performance flexible supercapacitors based on porous wood carbon slices derived from Chinese fir wood scraps

Wood carbon slices derived from wood scraps for constructing energy storage electrodes are very important, because they have excellent characteristics, such as structural stability, long cycle life, abundant resources and low prices. However, they have low capacitance as electrode materials for supercapacitors. In this paper, we design a new concept to obtain a porous wood carbon electrode with a large specific surface area. Firstly, CO2 is used to activate carbonized wood to open some closed pores and create some new pores. The activated wood is then soaked into KOH solution to further create new pores. Finally, the carbonized wood is modified with HNO3. After the above treatments, the number of nanopores with a diameter of approximately 2 nm is greatly increased within the wood carbon slices, and their specific surface area is increased to 703.5 m2 g−1. The single electrode material shows excellent performance with a high specific capacitance of 285.6 F g−1 and a high energy density of 38.0 mWh cm−3, which has more than twice the capacitance of the supercapacitor based on biomass carbon materials modified by diluted HNO3. Therefore, the application of wood scraps can meet the basic energy storage needs and realize the waste into treasure.