Zinc-bromide secondary cell

• US 3,929,506 A
• Filed: 05/18/1973
• Issued: 12/30/1975
• Est. Priority Date: 05/18/1973
• Status: Expired due to Term

• Current Assignee: Gerhard Gritzner, James J. Leddy
• Original Assignee: Gerhard Gritzner, James J. Leddy
• Inventors: Leddy, James J., Gritzner, Gerhard
• Primary Examiner(s): Mack, John H.
• Assistant Examiner(s): Feeley, H. A.
• Application Number:
  US05/361,745
• Time in Patent Office: 956 Days
• Field of Search: 136/86A,30,93,95
• US Class Current: 429/199
• CPC Class Codes: H01M 10/365 Zinc-halogen accumulators
• CPC Class Codes: H01M 4/661 Metal or alloys, e.g. alloy coatings H01M4/669 take precedence
• CPC Class Codes: H01M 4/663 containing carbon or carbonaceous materials as conductive part, e.g. graphite, carbon fibres
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A zinc-bromine secondary cell is divided into two compartments by an ion exchange diaphragm. The electrolyte system includes an essentially bromide ion free, aqueous solution containing a zinc ion as an anolyte and a bromide ion containing catholyte. A method of operating the cell is disclosed.

Claims

1. A METHOD OF OPERATING A ZINC-BROMIDE SECONDARY CELL DIVIDED INTO ANODE AND CAHODE COMPARTMENTS BY A ZINC CAION ION EXCHANGE DIAPHRAGM COMPRISING ADDING A CATHOLYTE CONSISTING ESSENTIALLY OF AN AQOUEOUS SOLUTION OF AT LEAST ONE SALT SELECTED FROM THE GROUP CONSISTING OF AMMONIUM BROMIDE AND THE BROMIDES OF LITHIUM, SODIUM, POTASSIUM, BERYLLIUM, MAGNESIUM, CALCIUM, AND STRONTIUM TO THE CATHODE COMPARTMENT WITH A CATHODE DISPOSED THEREIN;

ADDING AN ANOLYTE CONSISTING ESSENTIALLY OF AN ESSENTIALLY BROMIDE ION FREE, AQUEOUS SOLUTION CONTAINING AT LEAST ONE SALT SELECTED FROM THE GROUP CONSISTING OF ZINC CHLORATE, ZINC CHLORIDE, ZINC IODIDE, ZINC TETRAFLUOROBORATE, ZINC FLUORODSILICATE AND ZINC NITRATE TO THE ANODE COMPARTMENT WITH AN ANODE DISPOSED THEREIN;

IMPRESSING AN ELECTROMOTIVE FORCE BETWEEN THE ANODE AND THE CATHODE TO DEPOSIT METALLIC ZINC ON THE ANODE, RELEASE BROMINE AT THE CATHODE AND PASS SUBSTANTIALLY ONLY CATIONS THROUGH THE DIAPHRAGM INTO THE ANODE COMPARTMENT.

2. The method of claim 1 including adjusting the anolyte pH to within the range of from about 0.5 to about 5.

3. The method of claim 1 including adjusting the anolyte pH to within the range of from about 3 to about 4.

4. The method of claim 1 wherein the catholyte is at least about a one molar solution of a bromide ion.

5. The method of claim 1 wherein the catholyte is at least about a four molar solution of a bromide ion.

6. The method of claim 1 wherein the catholyte is a saturated solution of the bromide salt.

7. The method of claim 1 wherein the bromide salt is present in an amount within the range of from about one mole per liter of solution to a saturated solution.

8. The method of claim 1 wherein the salt is lithium bromide.

9. The method of claim 1 wherein the anolyte is at least about a two molar solution of a zinc ion.

10. The method of claim 1 wherein the anolyte is at least about a two molar solution of the zinc salt.

11. The method of claim 1 wherein the zinc salt is selected from the group consisting of zinc chloride and zinc tetrafluoroborate.

12. The method of claim 9 wherein the anolyte contains a tetrafluoroborate ion.

13. The method of claim 9 wherein the anolyte contains an alkali chloride.

14. The method of claim 9 wherein the anolyte contains lithium chloride.

15. A zinc-bromine electrolytic cell comprising in combination an at least partially encasing body, a first electrode positioned in an anode compartment spaced apart from a second electrode positioned in a cathode compartment by a zinc cation ion exchange diaphragm adapted to minimize passage of bromide ions into the anode compartment, said diaphragm separating the anode compartment from the cathode compartment, and an electrolyte system at least at the time of initial cell operation consisting essentially of an aqueous solution containing at least one salt selected from the group consisting of ammonium bromide and the bromides of lithium, sodium, potassium, beryllium, mangesium, calcium and strontium disposed in the cathode compartment and an essentially bromide ion free, aqueous solution containing at least one salt selected from the group consisting of zinc chlorate, zinc chloride, zinc iodide, zinc tetrafluoroborate, zinc fluorosilicate and zinc nitrate disposed in the anode compartment.

16. A zinc-bromide secondary cell comprising in combination an at least partially encasing container, an anode positioned in an anode compartment spaced apart from a cathode positioned in a cathode compartment by a zinc cation ion exchange diaphragm adapted to substantially entirely prevent passage of bromide ions from the cathode compartment into the anode compartment, the diaphragm substantially entirely separating the anode compartment from the cathode compartment, and an electrolyte system at least at the time of initial operation consisting essentially of an aqueous solution of at least about a one molar solution of lithium bromide disposed in the cathode compartment and at least about a two molar zinc chloride, substantially bromide ion free, aqueous solution disposed in the anode compartment.