Thermally Expanded Graphite as Functional Material in the Technology of Electrode Material with Mixed Conductivity

Abstract

Methods of differential thermal analysis and cyclic voltammetry were used to examine the functional properties of thermally expanded graphite in an electrode material for electrochemical systems. This material contains platinum, carbon black, and proton-conducting polymer Nafion. It was shown that addition of thermally expanded graphite to the electrode material makes higher the thermal stability of Nafion. Under an electrochemical treatment, thermally expanded graphite compares well in stability against this treatment with the commonly used carbon black of the Vulcan XC-72 type. A mechanism is suggested for stabilizing the proton-conducting polymer Nafion in the presence of thermally expanded graphite. It was shown that thermally expanded graphite is promising for being used in the technology of electrode materials with mixed conductivity, which contain a proton-conducting polymer of the Nafion type, as a functional additive serving to improve the thermal stability.