Electrochemical Performance of a New Triazole Functionalized Ferrocene in Aqueous Redox Flow Batteries

Abstract

A new 1,2,3-triazole functionalized ferrocene (1,2,3-TAFc) produced by Cu(I)-catalyzed click reaction was investigated as positive electrolyte for aqueous organic flow batteries (AOFBs). The molecule is highly soluble in 1 M hydrochloric acid and displays high electrochemical reversibility. 1,2,3-TAFc demonstrated good stability during cycling with a low capacity decay (0.011%/cyc, 3.0%/day) and high Coulombic efficiency (99.4%) over 280 cycles when tested in a flow battery at low concentration. This low capacity decay was attributed to the instability of ferrocene. These findings indicate that a stable and water-soluble catholyte for AOFBs can be obtained with structural modifications of 1,2,3-TAFc. A new type of ferrocene catholyte for AOFBs based on a 1,2,3-triazole moiety was introduced. 1,2,3-TAFc was prepared easily via click chemistry with a one-pot, two steps reaction sequence with 73% overall yield. The CV and flow battery experiments demonstrated the reversible and stable nature of the material. The cycling battery tests show a high stability of 1,2,3-TAFc in acidic electrolyte with low capacity decay (0.011%/cyc) and high Coulombic efficiency (99.4%).image