Enhancement of energy density in organic redox capacitor by improvement of electric conduction network

Abstract

Organic compounds have attracted attention as inexpensive and environmentally friendly active materials for energy storage devices. Among them, quinonic compounds can achieve high power capabilities because of their fast redox reactions. To utilize the organic compounds, which have a poor electrical conductivity and which are soluble in the electrolyte, the construction of electric conductive network to hold the organic compounds is necessary. In this study, we enhanced the capacity in aqueous redox-capacitors with quinonic and hydroquinonic organic compounds supported in nanoporous carbon by adding a small amount of another highly conductive carbon. The improvement of the electric conduction path enabled a high loading ratio of organic active material to nanoporous carbon (>70 wt%) in the electrode with a high utilization rate. It also achieved the high energy density of 30 Wh kg−1 in the organic redox capacitor.