Vanadium-Polydopamine Flow Battery

Dopamine (DA) exhibits quinone/hydroquinone redox activity at similar to 0.77 V vs SHE. As the potential is sufficiently high, this can be a replacement to the VO2+/VO2+ redox couple (catholyte) of the vanadium redox flow battery. But DA undergoes polymerization into polydopamine (PDA) while cycling in the flow battery. Therefore, a hybrid flow battery was constructed with PDA coated thermally activated graphite felt positive electrode and V3+/V2+ in 3 M H2SO4 anolyte. The vanadium-PDA flow battery exhibits a capacity of similar to 275 mAh g(PDA)(-1) in the first cycle. When the battery was subjected to continuous galvanostatic charge-discharge up to 300 cycles, a capacity retention of similar to 86% was observed with coulombic efficiency close to > 99%. Besides, energy efficiency of similar to 63% at a current density of 5 A g(-1) was observed. The peak power density of the battery was found to be similar to 8.83 W g(-1) at a current density of similar to 14.31 A g(-1).

Automated summary

This study found that dopamine can serve as a replacement for the catholyte of vanadium redox flow batteries but undergoes polymerization during cycling. A hybrid flow battery was constructed with PDA-coated graphite felt positive electrode and V3+/V2+ anolyte, exhibiting high capacity retention, coulombic efficiency, energy efficiency, and peak power density.