Regensburg 2010 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 61: Poster II: Materials, Interfaces and Heterostructures

HL 61.16: Poster

Thursday, March 25, 2010, 18:00–20:00, Poster D1

Hybrid electrode for electrochemical capacitors consisting of a MnO₂ infiltrated carbon aerogel — •Christian Weber¹, Volker Lorrmann¹, Jens Pflaum^1,2, Gudrun Reichenauer¹, and Vladimir Dyakonov^1,2 — ¹Bavarian Centre for Applied Energy Research e.V. (ZAE Bayern), D-97074 Würzburg — ²Julius-Maximilians-University of Würzburg, Institute of Physics, Experimental Physics VI, D-97074 Würzburg

Electrochemical capacitors (EC) bridge the gap between conventional capacitors with high power but low energy density and batteries with high specific energy density but rather low power density. There are two types of EC: Double-layer supercapacitors, that store charges electrostatically in the Helmholtz-layer between the electrolyte and the electrode of large surface area, the latter typically consisting of activated carbon. In pseudocapacitance supercapacitors charging is of faradaic nature, e.g. by redox processes in MnO₂. We have prepared EC hybrid electrodes by infiltrating a carbon aerogel with MnO₂. Structural analysis of these electrodes shows a decrease of surface area with increasing MnO₂-loading. Cyclic voltammetry measurements reveal an increase of the total capacitance of the electrode with MnO₂ concentration. However, the increase in capacitance arises at the cost of the cycling behaviour: low conductivity of MnO₂ and narrowed electrolyte pathways resulting from dispersed MnO₂ lead to an increase in the total resistance of the electrode. Correlations between compostition, structural characteristics and electrochemical properties are discussed in detail.