Organic positive electrode active material for aqueous redox flow battery

Abstract

An organic positive electrode active material for aqueous redox flow batteries, and more particularly, to technology of applying an organic positive electrode active material to make up for the drawbacks of conventional aqueous redox flow batteries. An aqueous redox flow battery to which a particular positive electrode active material is applied has no problems regarding metal deposition, and can also be useful in realizing a high energy density because the positive electrode active material may be used at high concentration due to an increase in solubility in a solvent, attaining a high working voltage, and enhancing energy efficiency. Also, the aqueous redox flow battery has excellent economic feasibility because an expensive organic electrolyte is not used.

1 . An organic positive electrode active material for aqueous redox flow batteries, comprising:
 a compound represented by the following Formula 1:   
       
         
           
           
               
               
           
         
         wherein R 1  to R 5  are the same or different from each other, and each independently represent H, NH 2 , NO 2 , X, CX 3 , or CN, wherein X is a halogen element, 
         provided that at least one of R 1  to R 5  is not H. 
       
     
     
         2 . The organic positive electrode active material for aqueous redox flow batteries of  claim 1 , wherein the halogen element comprises F, Cl, Br, or I. 
     
     
         3 . The organic positive electrode active material for aqueous redox flow batteries of  claim 1 , wherein R 1  is NH 2 , NO 2 , or Cl, and R 2  to R 5  are H. 
     
     
         4 . The organic positive electrode active material for aqueous redox flow batteries of  claim 1 , wherein the compound represented by Formula 1 is para-aminophenol or nitrophenol. 
     
     
         5 . A positive electrode electrolyte for aqueous redox flow batteries, comprising:
 the positive electrode active material of  claim 1 ; and   an aqueous solvent.   
     
     
         6 . The positive electrode electrolyte for aqueous redox flow batteries of  claim 5 , wherein the positive electrode active material is included at a concentration of 0.01 to 5 M. 
     
     
         7 . The positive electrode electrolyte for aqueous redox flow batteries of  claim 5 , wherein the aqueous solvent comprises one or more selected from the group consisting of H 2 SO 4 , K 2 SO 4 , Na 2 SO 4 , H 3 PO 4 , H 4 P 2 O 7 , K 2 HPO 4 , Na 3 PO 4 , K 3 PO 4 , HNO 3 , KNO 3 , NaNO 3 , and a combination thereof. 
     
     
         8 . A redox flow battery which is charged/discharged, comprising:
 a positive electrode cell comprising a positive electrode and a positive electrode electrolyte;   a negative electrode cell comprising a negative electrode and a negative electrode electrolyte;   an ion exchange membrane disposed between the positive electrode cell and the negative electrode cell; and   a positive electrode electrolyte tank configured to supply a positive electrode electrolyte to the positive electrode cell by driving a pump and having a positive electrode electrolyte stored therein and a negative electrode electrolyte tank configured to supply a negative electrode electrolyte to the negative electrode cell by driving a pump and having a negative electrode electrolyte stored therein,   wherein each of the positive electrode electrolyte and the negative electrode electrolyte comprises an electrode active material and an aqueous solvent, and   the positive electrode active material included in the positive electrode electrolyte is the positive electrode active material of  claim 1 .   
     
     
         9 . The redox flow battery of  claim 8 , wherein the negative electrode electrolyte contains positive bivalent vanadium ions (V 2+ ) and positive trivalent vanadium ions (V 3+ ).