(103b) Method for Rapid Evaluation of Graphite Felt Electrode Stability in Vanadium Redox Flow Battery

Vanadium redox flow battery (VRFB) is potential electrochemical energy storage solution for residential batteries and grid stabilization. The long durability originating mainly from all-vanadium chemistry, represents the main advantage of the technology. The battery stack is constructed from several components, where membrane and graphite felt electrodes are largely responsible for its efficiency and durability.

In our contribution, we present the developed method for accelerated studies of degradation processes of felt electrodes and quantification of intensity of side reactions under defined conditions (state-of-charge, current density and temperature). Full-cell and half-cell characterization is used to evaluate the electrochemical changes of positive and negative electrode, separately. The method is applied to evaluate the effect of the battery operating conditions on the performance durability of various graphite felt materials in vanadium redox flow battery. Subsequent post mortem analysis of the felts in VRFB by relevant physico-chemical characterization techniques relates the performance decay with the changes in felt properties. We observed significant differences in the stability among individual felt materials and their treatment.