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.

Start-Stop Phenomena in Channel and Land Areas of a Polymer Electrolyte Fuel Cell (PEFC)

“…A well-known phenomenon, which causes carbon corrosion, is the inhomogeneous anode gas composition, due to cathode to anode air crossover. This effect was observed in phosphoric acid fuel cells (PAFCs) (1). More recently, similar corrosion processes have been identified during the start-up and shutdown process of PEFCs (2).…”

Start-Stop Phenomena in Channel and Land Areas of a Polymer Electrolyte Fuel Cell

“…This effect was reported for phosphoric acid fuel cells in 1990. 1 More recently, similar corrosion processes have been identified in PEFCs as a consequence of localized fuel starvation [2][3][4][5] and during the start-up and shutdown process. 3,6 Here the reverse current phenomenon 3 …”

Start-Stop Phenomena in Channel and Land Areas of a Polymer Electrolyte Fuel Cell

“…Mechanically and chemically induced membrane degradation, dissolution and migration of platinum catalyst particles and corrosion of the carbon support in the catalyst layer have been identified as major critical issues. Corrosion due to inhomogeneous anode gas composition is a well known source of degradation in phosphoric acid fuel cells [1]. More recently, similar corrosion processes have been identified in PEFCs, as a consequence of localized fuel starvation and during start-up or shut-down processes [2].…”