Electrochemical cell and method

• US 4,500,613 A
• Filed: 03/14/1984
• Issued: 02/19/1985
• Est. Priority Date: 03/14/1984
• Status: Expired due to Term

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Space Operations Company (Martin Marietta Corporation)
• Inventors: Galbraith, Andrew D.
• Primary Examiner(s): LeFevour, Charles F.
• Application Number:
  US06/589,308
• Time in Patent Office: 342 Days
• Field of Search: 429/69, 429/68, 429/67, 429/72, 429/70, 429/14, 429/13, 429/51, 429/50
• US Class Current: 429/69
• CPC Class Codes: H01M 12/04 composed of a half-cell of the fuel-cell type and of a half-cell of the primary-cell type

Abstract

A rotating cathode cell is provided with a lithium anode. An acid oxidizing agent and an aqueous electrolyte are supplied to the moving cathode surface such that they are carried to the electrochemical junction between the anode and the cathode. The acid oxidizer continuously dissolves the layer of reaction product (LiOH) forming on the anode, improving the power output per unit weight of the cell.

Claims

1. An electrochemical cell comprising:

a lithium anode;

an electrically conductive rotatable cathode having a surface spaced from said anode to define an electrochemical junction;

means for supplying an aqueous electrolyte that is reactive with lithium to said electrochemical junction;

means for supplying an acid oxidizing agent to said electrochemical junction, said oxidizing agent having the ability to dissolve the products of the reaction between lithium and said electrolyte;

means for moving said cathode surface transversely to said anode;

means for urging said anode towards said cathode as said anode is consumed, yet maintaining the spacing between said anode and cathode a distance selected such that cathode-anode contact and excessive electrochemical resistance do not occur; and

,

an external circuit connecting said anode and said cathode.

2. The electrochemical cell of claim 1 wherein said acid oxidizing agent is hydrochloric acid.

3. The electrochemical cell of claim 1 wherein said acid oxidizing agent is hydrofluoric acid.

4. The electrochemical cell of claim 1 wherein said means for moving said anode comprises means for varying the force with which said anode is urged toward said cathode so as to vary the distance between said anode and said cathode.

5. The electrochemical cell of claim 1 wherein said supply of aqueous electrolyte is made at a position of the cathode such that said movement of said cathode carriers said electrolyte to the electrochemical junction.

6. The electrochemical cell of claim 1 wherein said aqueous electrolyte is water.

7. The electrochemical cell of claim 1 wherein said supply of acid oxidizing agent is made at a position of the cathode such that movement of the cathode carries said acid oxidizing agent to the electrochemical junction.

8. The electrochemical cell of claim 1 wherein said supply of aqueous electrolyte and said supply of acid oxidizing agent are combined to create a single supply stream.

9. The electrochemical cell of claim 1 wherein said cathode is constructed of a material that is selected for a low hydrogen overpotential.

10. The electrochemical cell of claim 1 wherein said cathode is constructed of a material that is resistant to reaction with either the reactants or products of the cell reaction.

11. The electrochemical cell of claim 1 wherein said cathode is constructed of iron.

12. The electrochemical cell of claim 1 wherein said movement of said cathode surface transversely to said anode is rotation of said cathode about an axis that is parallel to the line of movement of said anode toward said cathode.

13. A method of producing high current electrical energy comprising the steps of:

moving an electrically conductive, electrochemically non-reactive low resistance cathode surface transversely to a lithium anode;

spacing said anode from said cathode surface to form a thin electrochemical junction between said anode and said cathode surface;

introducing to said electrochemical junction an aqueous electrolyte reactive with lithium;

introducing to said electrochemical junction an acid oxidizing agent capable of dissolving the products of the reaction between lithium and said electrolyte; and

drawing electrical current in an external electrical circuit connecting said anode and said cathode.

14. In a rotating cathode cell having means for moving the surface of an electrically conductive, electrochemically non-reactive low resistance cathode transversely to an alkali metal anode, means for spacing said anode from said cathode surface to form a thin electrochemical junction between said anode and said cathode surface, means for introducing to said electrochemical junction an aqueous electrolyte reactive with said alkali metal, and an external electrical circuit connecting said anode and said cathode, the improvement wherein said alkali metal is lithium and said cell includes means for introducing to said electrochemical junction an acid oxidizing agent capable of dissolving the products of the reaction between lithium and said electrolyte.

15. The improvement of claim 14 wherein said acid oxidizing agent is chosen from the group consisting of hydrofluoric acid and hydrochloric acid.