Molecular size exclusion effect extending the cycling stability of a non-aqueous redox flow battery

Non-aqueous organic redox flow batteries (NAORFBs) suffer from rapid capacity fading mainly due to the crossover of redox-active species across the membrane. Minimizing the crossover of redox-active species through ion exchange membranes remains a complex challenge in NAORFBs. To address the crossover issue, we approached the problem through a molecular size exclusion principle designing a dimer of viologen derivative as an anode material. Coupled with N-hexyl phenothiazine as a catholyte, a static cell was demonstrated, which exhibits an excellent cycling stability (100 cycles) with an average Coulombic efficiency of 90% at 10 mA cm−2 current density.