New phenazine based anolyte material for high voltage organic redox flow batteries

Herein, we report the synthesis and investigation of a novel phenazine derivative M1 with oligomeric ethylene glycol ether substituents as a promising anolyte material for non-aqueous organic redox flow batteries (RFBs). The designed material undergoes a reversible and stable reduction at −1.72 V vs. Ag/AgNO 3 and demonstrates excellent (>2.5 M) solubility in MeCN. A non-aqueous organic redox flow battery assembled using the novel phenazine derivative as an anolyte and a substituted triarylamine derivative as a catholyte exhibited high specific capacity (∼93% from the theoretical value), >95% Coulombic efficiency, 65% utilization of active materials and good charge-discharge cycling stability. A highly-soluble (>2.5 M) ethylene glycol substituted phenazine derivative is shown to be a promising anolyte material for non-aqueous redox flow batteries.