Lu Zhang1

1, Argonne National Laboratory, Lemont, Illinois, United States

Redox flow batteries (RFBs) are attractive for large scale energy storage applications for the electric grid of the future due to their scalable energy capacity and sustained discharge at peak power. RFBs store charge in energized fluids circulating between the cell and the external tanks. The performance of these devices critically depends on the energy density and chemical stability of the redox active molecules (ROMs) in these fluids.
In this talk, two novel bicyclical substituted dialkoxybenzene molecules, BODMA and BODEA, will be discussed for use as catholyte materials in NRFBs. These molecules have been engineered to provide greater solubility (in their neutral state) and improved chemical stability (in their charged state) as compared to other tetra-substituted dialkoxybenzenes. The structural differences between these two bicyclo-alkyl substituents have considerable effect on their electrochemical behaviour and physical properties. A hybrid flow cell using BODMA as the catholyte material demonstrated stable efficiencies and capacity over 150 cycles. Our study indicates that (when designed properly) full substitution in a small-molecule catholyte material can significantly improve electrochemical cycling performance, widening dramatically the structural space for optimization of such materials for NRFBs.