Annulated Dialkoxybenzenes as Catholyte Materials for Non-aqueous Redox Flow Batteries: Achieving High Chemical Stability Through Bicyclic Substitution

a) Capacity and efficiency profiles of the Li/BODMA cell; b) X-ray crystal structure of BODMA; c) optimized structures and selected atomic spin densities of BODMA radical cation; d) normalized decay kinetics of the integrated EPR signal from BODMA radical cation in various solvents.

Scientific Achievement

9,10-bis(2-methoxyethoxy)-1,2,3,4,5,6,7,8- octahydro-1,4:5,8-dimethanenoanthracene (BODMA) was developed for use as the catholyte in non-aqueous redox flow batteries. The bicyclic scaffolds prevent the ring-addition reaction, showing superior chemical stability in the charged state. A hybrid flow cell using this catholyte is operated for 150 charge-discharge cycles with a minimal loss of capacity.

Significance and Impact

BODMA fully prevents the dominating decomposition pathway of previous 1,4-dialkoxybenzene-based catholytes while retaining high battery compatibility. The exceptional performance of this material in the cycling tests places our redox system among the most promising flow cell chemistries ever reported.

Research Details

BODMA delivered a reversible redox potential of 4.0 V vs Li/Li+, a half life time of 120 hours in the charge state, and a stable performance over 150 cycles in a hybrid flow cell.

  • Single crystals and DFT calculations indicated that the constrained conformation of the bicyclic substituents is the key to maintain the electrochemical reversibility of BODMA.

DOI: 10.1002/aenm.201701272

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