Bis(diisopropylamino)cyclopropenium-arene Cations as High Oxidation Potential and High Stability Catholytes for Non-aqueous Redox Flow Batteries

Yichao Yan; Thomas P Vaid; Melanie S Sanford

doi:10.1021/jacs.0c07464

Bis(diisopropylamino)cyclopropenium-arene Cations as High Oxidation Potential and High Stability Catholytes for Non-aqueous Redox Flow Batteries

J Am Chem Soc. 2020 Oct 14;142(41):17564-17571. doi: 10.1021/jacs.0c07464. Epub 2020 Oct 2.

Authors

Yichao Yan^{1

2}, Thomas P Vaid^{1

2}, Melanie S Sanford^{1

2}

Affiliations

¹ Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States.
² Joint Center for Energy Storage Research (JCESR), 9700 South Cass Avenue, Argonne, Illinois 60439, United States.

PMID: 33006474
DOI: 10.1021/jacs.0c07464

Abstract

This Article describes the development of 1,2-bis(diisopropylamino)-3-cyclopropenylium-functionalized (DAC-functionalized) benzene derivatives as high-potential catholytes for non-aqueous redox flow batteries. Density functional theory (DFT) calculations predict that the oxidation potentials (in CH₃CN) of various DAC-benzene derivatives will range from +0.96 to +1.64 V vs Fc^+/0, depending upon the substituents on the benzene ring. To test these predictions, a set of eight DAC-arene derivatives were synthesized and evaluated electrochemically. The molecule 1-DAC-4-tert-butyl-2-methoxy-5-pentafluoropropoxybenzene was found to offer the optimal balance of high redox potential (E_1/2 = +1.19 V vs Fc^+/0) and charge-discharge cycling stability (with 92% capacity retention over 116 h of cycling at 0.3 M concentration in a symmetrical flow cell). This optimal derivative was successfully deployed as a catholyte in a non-aqueous redox flow cell with butyl viologen as the anolyte to yield a 2.0 V battery.