Optimization of Carbonaceous Materials and Electrolytes for High-Rate Capacitor Applications

摘要

A major focus supercapacitor development lies in increasing their energy density. However, the rate capability also has limitations, particularly due to the specifics of the interface between the electrolyte and the electrode surface. Microporous carbons from waste biomass are the state-of-the-art electrode materials for supercapacitors due to their relatively low cost, sufficient electronic conductivity, inertness, and high specific surface area, but their capacitive response is also restricted due to the limited control over carbon porosity. This work will provide a few examples on maximizing the rate capability of supercapacitors based on carbonaceous materials and aqueous and organic electrolytes. Particular emphasis will be dedicated on the dissimilar electrochemical response of supercapacitor electrodes under opposite polarizations. The effect of electrolyte concentration on the rate capability will also be considered. On the materials side, the preparation of superporous carbons with tuned porosities by a simple all-in-one route involving simultaneous polymerization, carbonization and in-situ chemical activation of selected precursors will be presented. Such superactivated carbons provide ultrarapid response with ～ 100 urn thick electrodes, and can be viewed as an attractive alternative to their low-dimensional counterparts for ultrahigh power applications since they provide much higher gravimetric energy density.