VANADIUM FLOW CELL
A Vanadium chemistry flow cell battery system is described. Methods of forming the electrolyte, a formulation for the electrolyte, and a flow system utilizing the electrolyte are disclosed. Production of electrolytes can include a combination of chemical reduction and electrochemical reduction.
1 . A method for providing an electrolyte solution, comprising:
chemically reducing an acidic solution/suspension of V 5+ to form a reduced solution; and
electrochemically reducing the reduced solution to form an electrolyte.
2 . The method of claim 1 , wherein chemically reducing includes
providing an aqueous acidic solution/suspension of V 5+ ;
reducing the V 5+ to obtain V (5−n)+ where n=1, 2, or 3; and
adjusting the acidity of the solution to achieve the reduced solution.
3 . The method of claim 2 , wherein the aqueous acidic solution includes a mixture of H 2 SO 4 and HCl.
4 . The method of claim 2 , wherein the concentration of H 2 SO 4 in the aqueous acidic solution is substantially 0%.
5 . The method of claim 2 , wherein the concentration of HCl in the aqueous acidic solution is substantially 0%.
6 . The method of claim 1 , wherein reducing the V 5+ includes adding an organic reducing agent.
7 . The method of claim 6 , wherein the organic reducing agent is one or more of a group consisting of methanol, formaldehyde, formic acid, ethanol, acetaldehyde, acetic acid, ethylene glycol, glycol aldehyde, oxaldehyde, glycolic acid, glycolic acid, glyoxalic acid, oxalic acid, 1-propanol, 2-propanol, 1,2-propanediol, 1,3-propanediol, glycerol, propanal, acetone, and propionic acid.
8 . The method of claim 6 , wherein CO 2 is emitted during the reduction process.
9 . The method of claim 1 , wherein reducing the V 5+ includes adding an inorganic reducing agent.
10 . The method of claim 9 , wherein the inorganic reducing agent is one or more of a group consisting of sulfur, sulfur dioxide, sulfurous acid, sulfide salts, sulfite salts, thiosulfate salts, and vanadium metal.
11 . The method of claim 1 , wherein electrochemically reducing includes
filling storage tanks of an electrochemical cell with the reduced solution; and
charging the electrochemical cell to obtain an electrolyte solution.
12 . The method of claim 1 , wherein the electrochemical cell is an electrophotochemical cell.
13 . The method of claim 11 , wherein the electrolyte solution includes V 3+ and V 4+ .
14 . The method of claim 11 , wherein the electrolyte solution is a positive electrolyte solution and the reduced solution is a negative electrolyte solution.
15 . The method of claim 11 , further including adding hydrogen gas to a positive side of the electrochemical cell to form HCl.
16 . The method of claim 2 , wherein adjusting the acidity of the solution results in a solution of approximately 2.5 M M VOCl 2 in about 4 M HCl.
17 . The method of claim 2 , wherein adjusting the acidity of the solution results in a solution of VO 2+ in HCl, where VO 2+ concentration can be 1 to 3.5 molar and acid concentration can be 1 to 8 molar.
18 . The method of claim 2 , further including addition of a catalyst to the acidic aqueous solution.
19 . The method of claim 18 , wherein the catalyst is about 1 ppm to about 100 ppm of Bismuth(III) salts.
20 . The method of claim 18 , wherein the catalyst is chosen from a group consisting of lead, indium, tin, antimony, and thallium.
21 . A flow cell battery system, comprising
a positive vanadium electrolyte;
a negative vanadium electrolyte;
a stack having a plurality of cells, each cell formed between two electrodes and having a positive cell receiving the positive vanadium electrolyte and a negative cell receiving the negative vanadium electrolyte separated by a porous membrane.
22 . The system of claim 21 , wherein the positive electrode and the negative electrode are VO 2+ in a solution of HCl.
23 . The system of claim 21 , wherein the positive electrode and the negative electrode are 2.5 M VO Cl 2 in 4.0M HCl.
24 . The system of claim 21 , wherein the positive electrode and the negative electrode are 3.0 M VO Cl 2 in 3.0M HCl.
25 . The system of claim 21 , wherein the positive electrode and the negative electrode are VO 2− in a solution of HCl and H 2 SO 4 .
26 . The system of claim 21 , wherein the positive electrode and the negative electrode are VOSO 4 in a solution of H 2 SO 4 .