Fabrication of wood-based self-supporting thick carbon symmetric electrodes with 3D structure and high energy storage

The abundance and renewability of wood could provide the basis for the use of wood-based carbon into the energy storage industry. However, it is a breakthrough in the construction of wood-based supported carbon electrodes with supporting, stability, reasonable porosity, high carbon loading based on wood natural biological structures. In this work, the self-supporting thick carbon symmetric electrode with 3D structure and high energy storage was constructed based on wood natural biological structure via a microwave hydrothermal and scientific gradient carbonization process. The high-loading and stable/penetrable porous structures of carbon electrode promote the superior electrochemical performance, robust compressive strength, long service life, wide acid-base application range. The areal capacitance value could reach 25.63 F·cm –2 (current density of 1 mA·cm –2 ), and the continuous cycle of up to 12000 times (200 mA·cm –2 ) can still reach 90 % capacitance retention. When assembled as a symmetrical supercapacitor, the total energy density is 8470 Wh·m –2 , and the power density is 2511.6 W·m –2 , and the overall weight of the double electrode is more than 80 mg(60 mg·cm –2 ). The supercapacitor electrode is no longer a small load that remains in the laboratory stage, which opens the possibility of practical application of the biomass supercapacitor electrode. • The self-supporting thick carbons was constructed based on wood natural biological structure. • Utilizing the green microwave-assisted hydrothermal method to regulate porosity and permeability of wood. • High-loading, stable, and penetrable porous carbon electrodes enable long service life and high energy–power density.