Method for preparing cathode electrolyte for redox flow batteries, and redox flow battery
The present disclosure relate to a method for preparing a cathode electrolyte for redox flow batteries including the steps of: forming a first cathode electrolyte by reducing vanadium pentoxide (V 2 O 5 ) in an acidic solution in the presence of a specific reducing compound; forming a second cathode electrolyte by reducing vanadium pentoxide (V 2 O 5 ) in an acidic solution in the presence of a linear or branched aliphatic alcohol having 2 to 10 carbon atoms; and mixing the first cathode electrolyte and the second cathode electrolyte, and to a redox flow battery including the cathode electrolyte obtained by the preparation method.
1. A method for preparing a cathode electrolyte for redox flow batteries comprising the steps of: forming a first cathode electrolyte by reducing vanadium pentoxide (V 2 O 5 ) in an acidic solution in the presence of at least one reducing compound selected from the group consisting of dicarboxylic acid containing a linear or branched alkylene group having 0 to 6 carbon atoms, hydrazine, and L-ascorbic acid;
forming a second cathode electrolyte by reducing vanadium pentoxide (V 2 O 5 ) in an acidic solution in the presence of a linear or branched aliphatic alcohol having 2 to 10 carbon atoms; and
mixing the first cathode electrolyte and the second cathode electrolyte.
2. The method for preparing a cathode electrolyte for redox flow batteries according to claim 1 ,
wherein the first cathode electrolyte and the second cathode electrolyte are mixed in a volume ratio of 12:1 to 1:1.
3. The method for preparing a cathode electrolyte for redox flow batteries according to claim 1 ,
wherein a concentration of the acidic solution in the first cathode electrolyte and the second cathode electrolyte is 0.1 M to 6 M.
4. The method for preparing a cathode electrolyte for redox flow batteries according to claim 1 ,
wherein the acidic solutions in the first cathode electrolyte and the second cathode electrolyte contain sulfuric acid, respectively.
5. The method for preparing a cathode electrolyte for redox flow batteries according to claim 1 ,
wherein a concentration of the vanadium pentoxide in the first cathode electrolyte and the second cathode electrolyte is 0.3 M to 3 M, respectively.
6. The method for preparing a cathode electrolyte for redox flow batteries according to claim 1 ,
wherein a concentration of the reducing compound in the first cathode electrolyte is 0.3 M to 3 M,
and a concentration of the aliphatic alcohol in the second cathode electrolyte is 0.3 M to 3 M.
7. The method for preparing a cathode electrolyte for redox flow batteries according to claim 1 ,
wherein a ratio of the concentration of the reducing compound relative to the concentration of vanadium pentoxide in the first cathode electrolyte is 0.8 to 1.2.
8. The method for preparing a cathode electrolyte for redox flow batteries according to claim 1 ,
wherein a ratio of the concentration of the aliphatic alcohol relative to the concentration of vanadium pentoxide in the second cathode electrolyte is 0.8 to 1.2.
9. A redox flow battery, comprising:
a cathode electrolyte for redox flow batteries prepared by the method of claim 1 ;
metal ions containing a V 2+ /V 3+ redox couple; and
an anode electrolyte containing a sulfuric acid solution.
10. The redox flow battery according to claim 9 , wherein the redox flow battery includes at least one unit cell, the unit cell comprising:
a separation membrane through which ions pass;
a pair of electrodes opposite to the center of the separation membrane; and
the cathode electrolyte and anode electrolyte which are present respectively in a cathode cell and an anode cell partitioned by the separation membrane.
11. The redox flow battery according to claim 9 ,
wherein the unit cell further includes a pair of flow frames attached to face each other on respective sides of the separation membrane.
12. The redox flow battery according to claim 9 ,
wherein the unit cell further includes a cell frame formed on the outer surface of the electrodes.
13. The redox flow battery according to claim 9 , further comprising:
a cathode electrolyte tank for storing the cathode electrolyte;
a cathode electrolyte pump for circulating the cathode electrolyte from the cathode electrolyte tank to the cathode cell of the unit cell during charge and discharge;
an anode electrolyte tank for storing the anode electrolyte; and
an anode electrolyte pump for circulating the anode electrolyte from the anode electrolyte tank to the anode cell of the unit cell during charge and discharge.