Methods and systems for pretreating bipolar plate and use thereof in redox flow battery

Abstract

Systems and methods are provided for electrochemical and/or chemical pretreatment of bipolar plates, for example, for plating electrodes in redox flow batteries. In one example, a method may include pretreating a bipolar plate for the redox flow battery by disrupting a surface of the bipolar plate. In some examples, pretreating the bipolar plate may include positioning the bipolar plate within the redox flow battery, and thereafter charging the redox flow battery at multiple discrete plating current densities for each of one or more initial charging cycles to electrochemically etch the surface. In additional or alternative examples, pretreating the bipolar plate may include soaking the bipolar plate in solution to chemically treat the surface. In this way, the bipolar plate may be pretreated via electrochemical etching and/or chemical treatment so as to reduce electrochemical performance losses and dendrite formation in the redox flow battery.

1 . A method for a redox flow battery, the method comprising:
 pretreating a bipolar plate for the redox flow battery by disrupting at least one surface of the bipolar plate; and   initiating charge cycling of the redox flow battery,   wherein the redox flow battery includes an electrode compartment, the electrode compartment housing the pretreated bipolar plate upon initiation of charge cycling.   
     
     
         2 . The method of  claim 1 , wherein pretreating the bipolar plate by disrupting the at least one surface comprises:
 positioning the bipolar plate within the electrode compartment; and   charging the redox flow battery at multiple discrete plating current densities for each charging cycle of one or more initial charging cycles to electrochemically etch the at least one surface, and   wherein initiating charge cycling comprises charging the redox flow battery at a single plating current density for each charging cycle following the one or more initial charging cycles to uniformly plate a plating electrode housed in the electrode compartment.   
     
     
         3 . The method of  claim 2 , wherein the one or more initial charging cycles comprises only one initial charging cycle. 
     
     
         4 . The method of  claim 2 , wherein each of the multiple discrete plating current densities increase sequentially. 
     
     
         5 . The method of  claim 1 , wherein the at least one surface is pristine and unetched prior to pretreatment; and
 wherein the at least one surface is etched following pretreatment.   
     
     
         6 . The method of  claim 1 , further comprising preforming iron plating at a plating electrode housed in the electrode compartment following pretreatment and prior to charge cycling. 
     
     
         7 . The method of  claim 1 , wherein pretreating the bipolar plate by disrupting the at least one surface comprises:
 cleaning the bipolar plate with isopropyl alcohol; and   soaking the cleaned bipolar plate in solution for an extended duration to chemically treat the at least one surface.   
     
     
         8 . The method of  claim 7 , wherein the solution comprises a ferric chloride solution. 
     
     
         9 . The method of  claim 7 , wherein the extended duration is at least 12 hours. 
     
     
         10 . The method of  claim 1 , further comprising:
 cleaning the bipolar plate by soaking in acidic solution after pretreating the bipolar plate and before initiating charge cycling.   
     
     
         11 . A redox flow battery system, comprising:
 positive and negative electrode compartments respectively housing positive and negative electrodes;   a first bipolar plate positioned in the negative electrode compartment and in fluidic communication with the negative electrode; and   a second bipolar plate positioned in the positive electrode compartment and in fluidic communication with the positive electrode,   wherein a surface of the first bipolar plate facing toward the negative electrode is etched and roughened, and   wherein metal plating formed on the surface is substantially free of cracking and excess particulates and flakes.   
     
     
         12 . The redox flow battery system of  claim 11 , wherein the surface is etched and roughened by each of performing step charging of the redox flow battery system at a plurality of sequentially increasing plating current densities and soaking the surface in solution. 
     
     
         13 . The redox flow battery system of  claim 11 , wherein the first bipolar plate is formed by injection molding or compression molding a graphite composite starting material. 
     
     
         14 . The redox flow battery system of  claim 11 , wherein the redox flow battery system is an all-iron hybrid redox flow battery system.