Methods and system for manufacturing a redox flow battery system by roll-to-roll processing

Abstract

Methods and systems are provided for manufacturing a bipolar plate for a redox flow battery. In one example, the bipolar plate is fabricated by a roll-to-roll process. The bipolar plate includes a non-conductive substrate that is coupled to a negative electrode on a first surface and coupled to a positive electrode on a second surface, the first surface opposite of the second surface.

1 . A method of operating a redox flow battery system, comprising:
 pumping negative electrolyte from a negative electrolyte chamber through a negative electrode compartment side;   pumping positive electrolyte from a positive electrolyte chamber through a positive electrode compartment side; and   preventing bulk mixing of the positive electrolyte and the negative electrolyte via a separator positioned between the negative electrode compartment side and the positive electrode compartment side, wherein pores of the separator include a cross-linked polymer network formed by cross-linked polymer gel, the cross-linked polymer gel including functional groups interacting with cationic constituents of the positive electrolyte and the negative electrolyte.   
     
     
         2 . The method of  claim 1 , wherein the separator is formed as a continuous sheet by a calendaring process. 
     
     
         3 . The method of  claim 1 , wherein a porosity of the separator is at least 75%. 
     
     
         4 . The method of  claim 1 , wherein the separator is fluid impermeable and ion conducting. 
     
     
         5 . The method of  claim 1 , wherein a surface of the separator contacting the negative electrolyte includes a plurality of ribs. 
     
     
         6 . The method of  claim 5 , further comprising charging the redox flow battery system and forming gas bubbles in the negative electrode compartment side, wherein the plurality of ribs define flow channels promoting removal of the gas bubbles. 
     
     
         7 . A redox flow battery system, comprising:
 a battery cell including a negative electrode compartment and a positive electrode compartment;   a negative electrode and negative electrolyte included in the negative electrode compartment;   a positive electrode and positive electrolyte included in the positive electrode compartment; and   a separator positioned between the negative electrode compartment and the positive electrode compartment, wherein a surface of the separator is in face sharing contact with the negative electrode.   
     
     
         8 . The redox flow battery system of  claim 7 , wherein the separator is fluid impermeable and prevents flow of Fe 3+  from the negative electrode compartment to the positive electrode compartment. 
     
     
         9 . The redox flow battery system of  claim 7 , wherein the separator allows exchange of H+ between the negative electrode compartment and the positive electrode compartment. 
     
     
         10 . The redox flow battery system of  claim 7 , wherein the separator is formed of porous ultrahigh molecular weight polyethylene. 
     
     
         11 . The redox flow battery system of  claim 7 , wherein the separator includes carbon black, antioxidants, and a metal stearate lubricant. 
     
     
         12 . The redox flow battery system of  claim 7 , wherein the separator includes a plurality of ribs molded into the surface of the separator in face sharing contact with negative electrode. 
     
     
         13 . The redox flow battery system of  claim 12 , wherein each rib of the plurality of ribs is separated by a plurality of valleys. 
     
     
         14 . The redox flow battery system of  claim 7 , further comprising a bipolar plate positioned between the negative electrode and positive electrode, and wherein the separator and the bipolar plate are formed by a roll-to-roll process. 
     
     
         15 . A bipolar plate assembly for a redox flow battery, comprising:
 a flexible fluid-impermeable layer;   a first surface of the flexible fluid-impermeable layer coated with a negative electrode material; and   a second surface of the flexible fluid-impermeable layer bonded to a positive electrode material.   
     
     
         16 . The bipolar plate assembly of  claim 15 , wherein the flexible fluid-impermeable layer is one of a carbon fiber sheet imbedded with resin, a metal sheet, or a metal mesh filled with resin. 
     
     
         17 . The bipolar plate assembly of  claim 15 , wherein the negative electrode material is comprised of high surface area carbon particles. 
     
     
         18 . The bipolar plate assembly of  claim 17 , wherein the high surface area carbon particles form a structured surface conducive to deposition of iron metal. 
     
     
         19 . The bipolar plate assembly of  claim 15 , wherein the positive electrode material is graphite felt or carbon felt. 
     
     
         20 . The bipolar plate assembly of  claim 19 , wherein the flexible fluid-impermeable layer is adhered to the graphite felt or the carbon felt by electrically insulating resin.