To reach the political aims of the Kyoto Protocol and the Paris Agreement, the energy production must change from fossil fuels to sustainable sources like water, sun, and wind. But the fluctuation output of these techniques must be compensated by a smart grid. Herein, the integration of large-scale energy storage systems is inevitable. The possibility to use cheap organic molecules in “green” and non-toxic electrolytes make the emerging technology of organic redox flow batteries a promising candidate for this mission. Nevertheless, this battery concept suffers from many problems. One of the major ones is the insufficient stability of the active materials. To overcome this technical teething trouble, a combination of material and sensor development to investigate and mitigate decomposition processes is required. But currently, the research is more focused on development of new redox-active molecules with intrinsically higher stabilities than on investigating, understanding, and improving the underlying processes. Beside some exceptions, most research groups concentrate on demonstrating stabilities by cycling the material as often as possible. In addition, the influence of the used SOC of the battery is mostly uninvestigated. A battery management system which might limit the used SOC could improve the device lifespan. Therefore, precise, fast, and cheap monitoring systems for SOC and SOH determination are needed. The commonly applied techniques suffer from major drawbacks, like expensive equipment, material limitations, temperature dependency, and the need for (re)calibrations to name only a few. A protocol that is capable of monitoring these parameters on the electrolyte level and not on the battery level could unlock a deeper understanding of the ongoing processes inside the device or electrolyte. Possible device lifespan improvements could then not only be addressed by the material itself but also by the cycling conditions or other external factors
