Towards high volumetric capacitance via embedding a porous biomass carbon with redox organic molecules

Activated carbon-based supercapacitors can show high gravimetric capacitance and power density but inferior volumetric capacitance and energy density, which are mainly caused by the low density of carbon electrode materials and relevant energy storage processes overly depending on the huge inner space of porous carbon to finish ion adsorption/desorption. To make a difference, carbon-quinhydrone composites are fabricated by simply embedding a general hierarchical porous biomass carbon selected as the matrix with redox quinhydrone molecules. Related findings reveal that the strategy via organizing the biomass activated carbon with quinhydrone molecules creates a notable contribution to pseudo capacitance, bulk density increase, and transformation in pore size distribution as well as structural texture change. More than that, the participation of quinhydrone molecules makes the capacitive-controlled charge/discharge mechanism of the carbon-quinhydrone composites differ from that of the mixed control of interface reaction and diffusion belonging to the carbon matrix used alone, which contributes to a faster charge transfer and efficient charge storage scheme. Accordingly, the related single electrode and an asymmetric supercapacitor device based on this composite with a bulk density of 0.91 g cm-3 can offer high volumetric capacitance and energy density up to 490.5 F cm-3 and 21.6 Wh L-1, respectively.

Automated summary

Carbon-quinhydrone composites, fabricated by embedding biomass activated carbon with quinhydrone molecules, show improved volumetric capacitance and energy density in supercapacitors. The participation of quinhydrone molecules contributes to higher pseudo capacitance, increased bulk density, faster charge transfer, and efficient charge storage.