In this study, the use of biorefined wood materials in the fabrication of organic redox supercapacitors is proposed. Oak-derived hard carbon (HC) is revealed to have a nanographite domain structure, showing conductivity as high as that of artificial graphite. The CO2-activated hard carbon (A–HC) has a conductivity one order higher than that of commercial activated carbon, with a surface area of 1126 m2 g−1. The energy densities of supercapacitors composed of a tetrachlorohydroquinone cathode and anthraquinone (AQ) or 1,5-dichloroanthraquinone (DCAQ) anode are 19.0 and 13.8 Wh kg−1, respectively. The utilization rate of AQ with A–HC is 97.6% (250.9 mAh g−1), which is much higher than those in previous reports (≈80%). After 1000 cycles, 91.0% of the discharge capacity is retained when the DCAQ anode is used. Biorefined wood materials lead to a remarkable improvement in the operation of organic supercapacitors. This is intriguing, because the functional carbon material herein is easily prepared from a natural resource, wood, whereas numerous studies have prepared such materials from artificial chemical sources. Therefore, the use of oak-derived HC enhances the usability of organic active materials for energy storage devices and potentially has a far-reaching impact on the environment.
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