Novel Explanation of Unusual Localized Corrosion in Energy Conversion Devices

Abstract

Corrosion on the cathode or anode side of an electrochemical device is generally believed to be driven by the potential of that electrode. However, at times, unusually high localized corrosion has been observed in electrochemical cells having flowing reactants, such as fuel cells and flow batteries, which is not explainable by the "normal" electrode potential. This (observed) unusual corrosion is caused by the creation of two electrochemical cells in series within a single cell embodiment, where one cell becomes a power source and drives the other cell. The driven cell can have a depolarized counterelectrode, thus exposing the anode of the driven cell to a very high corrosion potential. Detailed mechanistic explanation and experimental verification of the mechanism are presented in this paper using a phosphoric acid fuel cell as an example.