Process for producing iron electrode

• US 3,898,098 A
• Filed: 05/31/1974
• Issued: 08/05/1975
• Est. Priority Date: 06/21/1971
• Status: Expired due to Term

• Current Assignee: Robert D. Giles
• Original Assignee: Robert D. Giles
• Inventors: Giles, Robert D.
• Primary Examiner(s): Skapars, Anthony
• Application Number:
  US05/475,289
• Time in Patent Office: 431 Days
• Field of Search: 136/25,34,35,75-78,12R,154 204/48,10
• US Class Current: 205/66
• CPC Class Codes: H01M 4/52 of nickel, cobalt or iron
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Process for producing electrode structures which are suitable for use as the negative electrode in nickel-iron storage batteries. The active mass is electrodeposited under controlled conditions from an aqueous electrolyte containing ferrous ions and ammonium ions, and preferably, in addition, a sulphur containing compound and a buffering agent to maintain the pH in the range of 1 to 5.5. The electrolyte can also contain a small amount of copper ion.

Claims

1. A METHOD FOR PRODUCING IRON ACTTIVE MASS WHICH COMPRISES ELECTRODEPOSITING SAID MASS ON A CATHODE FROM AN AQUEOUS ELECTROLYTE CONTAINING FERROUS ION AND AMMONIUM ION SAID ELECTROLYTE BEING CHARACTERIZED BY HAVING A PH OF ABOUT 2.5 TO 5.5 AND THE ELECTRODEPOSITION BEING CHARACTERIZED BY CONTROLLED INTERRELATION OF CATHODE CURRENT DENSITY, PH AND COMPOSITION OF THE ELECTROLYTE TO PROVIDE AN ELECTRODEPOSIT OF IRON ACTIVE MASS COMPRISING ESSENTIALLY OXIDIC IRON WITH NO MORE THAN ABOUT 60% BY WEIGHT OF THE ACTIVE MASS BEING IN THE METALLIC UNOXIDIZED STATE.

2. A method as in claim 1 wherein the ferrous ion and ammonium ion are derived from a ferrous ammonium salt selected from the group consisting of ferrous ammonium sulphate, and ferrous ammonium sulphamate.

3. A method as in claim 2 which comprises maintaining the ferrous ammonium salt at a concentration of from about 0.1M to about 0.65M, and electrodepositing at a cathode current density up to about 140 milliamperes per square centimeter.

4. A method as in claim 3 wherein the cathode current density is about 20 to about 100 mA/cm2.

5. A method as in claim 4 wherein the pH is about 3 to about 4.4.

6. A method as in claim 3 wherein the pH is maintained within the required range by buffering the electrolyte with a buffer selected from the group consisting of alkali metal phosphates, alkali metal tartrates and alkali metal lactates.

7. A method as in claim 1 where the electrolyte contains a water soluble, sulphur containing material having sulphur in an oxidation state lower than the oxidation state of sulphur in the sulfate ion and which is incapable of releasing into the electrolyte any significant amount of sulfide ion.