Redox Flow Batteries Based on Supporting Solutions Comprising a Mixture of Acids

Abstract

Redox flow battery systems having a supporting solution that contains Cl” ions can exhibit improved performance and characteristics. Furthermore, a supporting solution having mixed SO 4 2− and Cl − ions can provide increased energy density and improved stability and solubility of one or more of the ionic species in the catholyte and/or anolyte. According to one example, a vanadium-based redox flow battery system is characterized by an anolyte having V 2+ and V 3+ in a supporting solution and a catholyte having V 4+ and V 5+ in a supporting solution. The supporting solution can contain Cl − ions or a mixture of SO 4 2− and Cl − ions.

1 . A redox flow battery system having a supporting solution, the supporting solution comprising a mixture of SO 4   2−  and Cl −  ions. 
     
     
         2 . The system of  claim 1 , wherein the Cl to SO 4   2−  concentration ratio is between 1:100 and 100:1. 
     
     
         3 . The system of  claim 1 , wherein the Cl −  to SO 4   2−  concentration ratio is between 1:10 and 10:1. 
     
     
         4 . The system of  claim 1 , wherein the Cl −  to SO 4   2−  concentration ratio is between 1:3 and 3:1. 
     
     
         5 . The system of  claim 1 , wherein the redox flow battery system is a Fe/Cr system. 
     
     
         6 . A redox flow battery system comprising a supporting solution, the supporting solution characterized by containing a mixture of SO 4   2−  and F −  ions.