Cost-efficient high energy density redox flow battery

Abstract

Methods and systems are provided for a redox flow battery system. In one example, the redox flow battery is adapted with an additive included in a battery electrolyte and an anion exchange membrane separator dividing positive electrolyte from negative electrolyte. An overall system cost of the battery system may be reduced while a storage capacity, energy density and performance may be increased.

1 - 13 . (canceled) 
     
     
         14 . A method for a redox flow battery system comprising;
 plating a metal from an electrolyte solution onto a negative electrode during charging of the redox flow battery system;   deplating the metal from the negative electrode into the electrolyte solution during discharging of the redox flow battery system; and   transporting anions across an anion exchange membrane separator positioned in the electrolyte solution, the anion exchange membrane separator configured to separate a negative electrode compartment from a positive electrode compartment of the redox flow battery system;   wherein the electrolyte solution in the negative electrode compartment comprises stearic acid as a plating additive to form uniform and crack-free layers of metal at the negative electrode.   
     
     
         15 . The method of  claim 14 , wherein transporting the anions across the anion exchange membrane separator includes transporting the anions without transporting cations or complexes across the separator. 
     
     
         16 . The method of  claim 14 , wherein transporting the anions across the anion exchange membrane separator includes transporting the anions from a region of the redox flow battery system of lower overall positive bias to a region of higher overall positive bias. 
     
     
         17 . The method of  claim 14 , wherein the electrolyte solution consists of redox active species. 
     
     
         18 . (canceled) 
     
     
         19 . (canceled) 
     
     
         20 . (canceled) 
     
     
         21 . The method of  claim 14 , wherein the anion exchange membrane separator is formed from one or more of a polymer network with ion transport selectivity, a covalent organic framework, and a pre-fabricated, commercially available material. 
     
     
         22 . The method of  claim 21 , wherein the polymer network comprises one or more of heteroaromatic compounds, aniline, olefins, and sulfones. 
     
     
         23 . The method of  claim 14 , wherein the anion exchange membrane separator is fabricated by one of grafting, surface coating, solvent, casting, and conformal coating. 
     
     
         24 . The method of  claim 14 , wherein transporting the anions across the anion exchange membrane separator comprises transporting Cl −  while inhibiting transport of iron cations. 
     
     
         25 . The method of  claim 14 , wherein transporting the anions across the anion exchange membrane separator comprises transporting Cl −  while inhibiting transport of the stearic acid. 
     
     
         26 . The method of  claim 14 , wherein discharging the redox flow battery system comprises providing up to 100 hours of energy to power an external system. 
     
     
         27 . The method of  claim 14 , wherein iron cations of the metal, bound by the stearic acid, plate onto the negative electrode as a stack of evenly spaced apart monolayers of iron that are separated by layers formed of the trailing, chemically inert tail of the stearic acid. 
     
     
         28 . The method of  claim 27 , wherein the iron cations comprise divalent and trivalent iron. 
     
     
         29 . The method of  claim 14 , wherein the crack-free and uniform layers of metal at the negative electrode are self-assembled monolayers of iron, the iron bound by the stearic acid. 
     
     
         30 . The method of  claim 14 , wherein a free energy of the metal is lowered when bound by the stearic acid and the lowering of the free energy causes the metal to self-assembly into layers separated by the stearic acid. 
     
     
         31 . The method of  claim 14 , wherein the crack-free and uniform layers of metal have a thickness of over  1  cm. 
     
     
         32 . The method of  claim 14 , wherein more than one molecule of the stearic acid bonds with each metal center of the crack-free and uniform layers of metal. 
     
     
         33 . The method of  claim 14 , wherein the anion exchange membrane separator comprises pH resistant functional groups.