Superior Pseudocapacitive Behavior of Confined Lignin Nanocrystals for Renewable Energy- Storage Materials

Strong demand for high-performance energy-storage devices has currently motivated the development of emerging capacitive materials that can resolve their critical challenge (i.e., low energy density) and that are renewable and inexpensive energy-storage materials from both environmental and economic viewpoints. Herein, the pseudocapacitive behavior of lignin nanocrystals confined on reduced graphene oxides (RGOs) used for renewable energy-storage materials is demonstrated. The excellent capacitive characteristics of the renewable hybrid electrodes were achieved by synergizing the fast and reversible redox charge transfer of surface-confined quinone and the interplay with electron-conducting RGOs. Accordingly, pseudocapacitors with remarkable rate and cyclic performances (approximate to 96% retention after 3000cycles) showed a maximum capacitance of 432Fg(-1), which was close to the theoretical capacitance of 482Fg(-1) and sixfold higher than that of RGO (93Fg(-1)). The chemical strategy delineated herein paves the way to develop advanced renewable electrodes for energy-storage applications and understand the redox chemistry of electroactive biomaterials.