Executive Summary : | Grid level energy storage is becoming increasingly popular due to the increasing use of renewable energy sources, with redox flow batteries (RFBs) being a viable option. However, the slow kinetics of redox reactions, limited operating temperature range, and poor air stability of V ions in lower oxidation states have led to the search for alternative redox couples. Organic flow batteries are cost-effective, promising, and have a wide range of redox potential due to their tuneable structure. A third type of RFB using polyoxometalates (POM) has been recently reported, showing higher power densities and faster kinetics due to delocalization of electron transfer over several metal centers. However, none of the POM RFBs used so far have been advanced to commercialization due to complex synthesis processes, electrode surface modifications, or differences in volumetric capacity of electrolytes. An asymmetric POM RFB was recently delineated by Friedl et. al. (2018), using PV14 as catholyte and SiW12 as anolyte. To improve power density, resistive losses need to be reduced, and a thinner membrane can be implemented to reduce ohmic losses and use an efficient flow metric to compensate for losses due to Rdiff. To increase energy density, the number of electron transfer and concentration of POM must be increased. The first stage of the project involves synthesizing and characterizing the POM for catholyte PV14, followed by electrochemical characterization and cell characteristics study on bare flat glassy carbon electrodes. |