Organic Sodium Based Flow Batteries Utilizing Transition Metal and Metal Free Complexes

The utilization of redox flow batteries (RFBs) for large scale energy storage has acquired much interest due to the large cycle life and flexibility in system via the decoupling of energy and power. Although RFBs show increasing promise, they suffer from low energy density due to the utilization of aqueous electrolytes which are limited in voltage due to hydrogen and oxygen evolution. A new hybrid sodium based flow battery has been developed which utilizes a molten sodium alloy anode separated from the flowing catholyte by a solid beta”-alumina membrane. An organic catholyte consisting of either transition metal complexes which can be cycled through several oxidation states or metal free organic complexes has been investigated in conjunction with the molten anode. Spectrographic techniques such as UV-Vis and IR absorption will be used to analyze the transitions at different states of charge and at various cycles to determine both the change in valence of the active species as well as the shift of chemical bonds which may affect the reversibility of the systems.