System and method for operation of a metal-air secondary battery

• US 3,915,745 A
• Filed: 11/09/1973
• Issued: 10/28/1975
• Est. Priority Date: 12/09/1972
• Status: Expired due to Term

• Current Assignee: Hironosuke Ikeda, Masahiro Ide, Masaru Inaba
• Original Assignee: Hironosuke Ikeda, Masahiro Ide, Masaru Inaba
• Inventors: Ikeda, Hironosuke, Ide, Masahiro, Inaba, Masaru
• Primary Examiner(s): Mack, John H.
• Assistant Examiner(s): Feeley, Hugh A.
• Application Number:
  US05/414,253
• Time in Patent Office: 718 Days
• Field of Search: 136/86A,86S,159
• US Class Current: 429/406
• CPC Class Codes: H01M 10/42 Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells H01M10/60 takes precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

The present invention comprises a system for and method of operation of a metal-air secondary battery of an electrolyte circulation type comprising a charging circulation system including an electrolyte tank with a large capacity detachably connectable by a pair of pipe connectors to the apparatus and a discharging circulation system with a small capacity, these two circulation systems being alternatively changed over by means of a two-circuit three-way cock. In a charging mode, the body of a metal-air secondary battery is connected to said tank which is usually installed in a charging station so that an active metal may be efficiently electrodeposited using an ordinary circulation method, and in a discharging mode, the tank is detached and the battery is connected to the discharging circulation system so that a minimum quantity of electrolyte, necessary for discharging, may be circulated. Therefore, the system of the present invention is advantageous in that the weight and capacity size of a power supply are reduced by half as compared with those of conventional systems, with the result of an improved ratio of energy to weight and size, and is extremely useful when used in a vehicle borne metal air battery, for example, an air zinc battery for an electric automobile.

Claims

1. AN APPARATUS FOR CIRCULATING ELECTROLYTE IN A METAL-AIR BATTERY COMPRISING, IN COMBINATION, A METAL-AIR BATTERY HAVING A PARTIAL ELECTROLYTE CIRCULATING SYSTEM, FIRST ELECTROLYTE CIRCULATING MEANS OF RELATIVELY LARGE CAPACITY, MEANS FOR DETACHABLY CONNECTING SAID FIRST ELECTROLYTE CIRCULATING MEANS TO SAID PARTIAL ELECTROLYTE CIRCULATING SYSTEM OF SAID BATTERY TO FORM, SELECTIVELY A CLOSED CIRCULATING SYSTEM THEREWITH FOR CIRCULATING ELECTROLYTE THROUGH SAID BATTERY DURING A BATTERY CHARGING OPERATION, SECOND ELECTROLYTE CIRCULATING MEANS HAVING A SUBSTANTIALLY SMALLER CAPACITY THAN THE CAPACITY OF SAID FIRST ELECTROLYTE CIRCULATING MEANS AND CONNECTED SELECTIVELY IN COMMUNICATION WITH SAID PARTIAL ELECTROLYTE CIRCULATING SYSTEM OF SAID BATTERY FOR CIRCULATING ELECTROLYTE THROUGH SAID BATTERY IN A CLOSED CIRCULATION SYSTEM DURING A BATTERY DISCHARGING OPERATION, AND FLOW PATH SWITCH MEANS FOR SELECTIVELY CONNECTING SAID FIRST AND SECOND ELECTROLYTE CIRCULATING MEANS WITH SAID PARTAL ELECTROLYTE CIRCULATING SYSTEM OF SAID BATTERY DURING BATTERY CHARGING AND DIDCHARGING OPERATIONS, RESPECTIVELY.

2. Apparatus for circulating electrolyte in a metal-air battery in accordance with claim 1, wherein said first electrolyte circulation means comprises an electrolyte tank and a circulation pump.

3. Apparatus for circulating electrolyte in a metal-air battery in accordance with claim 1, wherein said battery comprises a battery body, a distributor and an electrolyte collector.

4. Apparatus for circulating electrolyte in a metal-air battery in accordance with claim 1, wherein said detachable connecting means include valve means responsive to detachment to close the flow path therethrough automatically.

5. Apparatus for circulating electrolyte in a metal-air battery in accordance with claim 1, wherein said flow path switch is a one-circuit switch.

6. Apparatus for circulating electrolyte in a metal-air battery in accordance with claim 2, wherein said circulation pump forces electrolyte from said tank to said battery.

7. Apparatus for circulating electrolyte in a metal-air battery in accordance with claim 2, wherein said circulation pump forces electrolyte from said battery and into said tank.

8. A method of operation of a metal-air battery having an active metal and a partial circulation system for circuLation of an electrolyte therethrough and having associated therewith a first electrolyte circulating means of relatively large capacity and a second electrolyte circulating means of relatively small capacity, said battery having a charging mode of operation for depositing said active metal within said battery and a discharging mode of operation for supply of output power from said battery during which said active metal is converted into ions in solution in said electrolyte, comprising:

during said charging mode of operation of said battery, selectively connecting said first electrolyte circulation means to said partial electrolyte circulating means of said battery to form a closed system therewith and circulating a relatively large quantity of electrolyte through said battery by said first electrolyte circulating means to convert active metal ions in solution in said electrolyte to said active metal deposits within said battery, and during a discharge mode of operation of said battery, disconnecting said first electrolyte circulating means of relatively large capacity from said battery and forming a closed system of said second electrolyte circulating means with said partial electrolyte circulating system of said battery, and circulating a relatively small quantity of electrolyte through said battery by means of said second electrolyte circulating means, said active metal deposited within said battery being converted to ions of said active metal in solution in said relatively small quantity of electrolyte.

9. A method of operation of a metal-air battery as recited in claim 8, wherein during said discharging mode of operation of said battery, said ions of said active metal in said electrolyte form deposits of an oxide of said active metal within said battery, and wherein the charging mode of operation of said battery further comprises:

preliminarily maintaining the electrolyte stationary in said battery while charging said battery with a current having a density less than half of that of an ordinary charging current for said battery, thereby to reduce said deposited oxide of said active metal to a deposit of said active metal.

10. A method of operation of a metal-air battery as recited in claim 8, wherein during said discharging mode of operation of said battery, said ions of said active metal in said electrolyte form deposits of an oxide of said active metal within said battery, and wherein the charging mode of operation of said battery further comprises:

initially and for a short time interval, circulating said relatively large quantity of electrolyte through said battery to dilute the concentration of metal ions in solution in said electrolyte within said partial electrolyte circulating system of said battery, terminating circulation of said relatively large quantity of electrolyte and maintaining the electrolyte stationary in said battery and preliminarily charging said battery with said stationary electrolyte therein, with a current having a density less than half that of an ordinary charging current for the said battery, thereby to reduce the deposited said active metal oxide within said battery to a deposit of said active metal, and thereafter charging said battery with an ordinary charging current while circulating said relatively large quantity of electrolyte through said battery by said first electrolyte circulating means.

11. A method of operation of a metal-air battery as recited in claim 8 wherein said electrolyte comprises potassium hydroxide and said active metal comprises a metal selected from the group consisting of zinc and cadmium.

12. A method of operation of a metal-air battery as recited in claim 9 wherein said discharging mode of operation of said battery is effective to produce a saturated solution of said active metal ions in said relatively small quantity of electrolyte and said deposit of said oxide of said active metal within said battery.