Aging Studies of Vanadium Redox Flow Batteries

A simple equivalent circuit based on a modified randles circuit has been developed and applied to assign different chemical and physical effects to a vanadium redox flow battery (VRFB) and the materials such as electrode, membrane and current collector. After that the test cell has been studied at different failure modes by electrochemical impedance spectroscopy. Some of the studied failure modes were corrosion of the current collectors due to electro-migration of sulphuric acid through graphite electrodes, hydrogen and oxygen evolution at higher voltages and a cracked membrane. The results show the possibility for a model based diagnostic of a battery system.