On the Capacity and Stability of a Biosynthesized Bis-quinone Flow Battery Negolyte

The use of naturally occurring quinones to produce moresustainableelectrolytes to use for renewable energy storage in redox flow batteries(RFBs) is still a new and rarely investigated subject. In this study,we demonstrate how the putative phoenicin and its dimer (diphoenicin)influence the capacity performance of phoenicin as a negolyte in aredox flow battery. To do this, we biosynthesized phoenicin by cultivatingthe filamentous fungus Penicillium phoeniceum and the resulting fungal extract contained multiple metabolites,putatively related to phoenicin, including the proposed phoenicindimer, which constituted 7% of the extract. When paired with potassiumferri/ferrocyanide as a posolyte in an RFB, the battery showed aninitial capacity of 1.58 Ah L-1. In contrast toour previous study, this corresponded to a two-electron reaction perbenzoquinone group. A detailed electrochemical and chemical analysisis conducted to shed light on this discrepancy and to provide furtherinsight into the chemical stability of phoenicin in an alkaline environment(pH = 14). A sustainable biosynthesizedfungal quinone mix of phoenicinstores four electrons per phoenicin molecule in a redox flow batterynegolyte.