Addressing Practical Use of Viologen- Derivatives in Redox Flow Batteries through Molecular Engineering

In practical scenarios, viologen-derivatives face an accelerated degradation in the unavoidable presence of traces of oxygen in large-scale redox flow batteries. Herein, we confirm the primary degradation mechanism and propose a straightforward, cheap, and fast method to evaluate the stability of viologen-derivatives toward this degradation. Considering that the cleavage of the N-substituent is the main proposed pathway for viologen degradation, a new viologen-derivative, bearing an alkylsulfonate chain with a secondary carbon center joined to the N atom, is synthesized to illustrate how molecular engineering can be used to improve stability.

Automated summary

In the presence of traces of oxygen, viologen-derivatives in redox flow batteries undergo accelerated degradation. We have identified the primary degradation mechanism and proposed a cost-effective and efficient method to evaluate the stability of viologen-derivatives in relation to this degradation. Through molecular engineering, we have synthesized a new viologen-derivative with improved stability by introducing an alkylsulfonate chain with a secondary carbon center joined to the N atom.