Quinone Redox Flow Battery Electrode Testing

The efficiency and cost of a redox flow battery (RFB) can be significantly affected by the electrode selected for scale-up.  Carbon felt has traditionally been used as the electrode in flow batteries, but flow battery design requires it to be highly compressed thereby requiring high pumping power and causing battery leakage problems.  Additionally, by compressing the felt, the electrolyte must be pumped through the felt at enough pressure to ensure uniform flow through the felt. Carbon felt has a high specific surface area and good electrical conductivity. Any replacement must meet the needs of the flow battery system in terms of specific surface area and electrical conductivity. Prototype alternatives to the homogeneous carbon felt were screening tested, indicating that configurations of foam and felt composite were useful to lower pressure drop through the cell while providing the necessary electrical continuity for RFB operation.

Quinone electrolytes were employed in each half-cell to test the charge/discharge performance of the RFB. A design of experiment methodology was used for a composite electrode, while varying current and electrolyte flow. Interesting delayed double-electron transfer effects were noted from the redox of the quinone electrolytes. Testing has shown that the composite electrode has advantages over the felt. The testing confirmed that the composite electrode has the potential of increasing the efficiency of the flow battery. Testing results to date will be reported indicating the redox of the quinone electrolytes when the composite electrode configuration is changed.