Process for producing battery electrodes by electrochemical reduction
AssigneeGlobe-Union Inc.
InventorsRichard L. Beauchamp, Leonard J. Burant
Life of this patent
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Abstract
Battery electrodes, such as those having nickel hydroxide as electrochemically active material, may be produced according to the invention by reducing the electrodes after normal impregnation processing is completed to remove residual nitrate in the impregnated electrode. The alkali metal hydroxide electrolyte utilized in this reduction may be reused up to 7 to 10 times. The reduced electrodes can be used directly to assemble batteries or may be processed further by a formation and characterization electrolytic cycling of charge and discharge. The alkali metal hydroxide electrolyte utilized in this characterization may be reused up to 22 times.
Claims20
A method for reducing an electrode which comprises:
- immersing a porous metal electrode impregnated with a metal hydroxide in an aqueous alkali metal hydroxide solution having an initial alkali metal hydroxide concentration not greater than about 10 wt. %;
- and
- applying an electrical current to said impregnated electrode under conditions effective to cathodically reduce said impregnated electrode, without oxidation thereof, to convert nitrate ions in said electrode to ammonia.
A method for producing metal hydroxide electrodes, comprising:
- impregnating a porous metal plaque disposed in an aqueous metal nitrate solution with a metal hydroxide material which forms by precipitation on said plaque, thereby forming an impregnated electrode;
- then reducing said electrode cathodically in aqueous alkali metal hydrozide solution having an alkali metal hydroxide concentration not greater than about 10 wt. % by application of an electrical current having a density of from about 1 to 20 ma/cm.sup.2 for at least about one hour under conditions effective to convert nitrate ions to ammonia in situ;
- and then electrolytically cycling said electrode in an alkali metal hydroxide solution.
A method for producing a nickel hydroxide electrode comprising the steps of:
- (a) impregnating a porous nickel plaque with nickel hydroxide in an aqueous nickel nitrate solution at a current density sufficient to precipitate electrochemically active nickel hydroxide material in the pores of the plaque to form an electrode;
- then
- (b) washing and drying the impregnated electrode;
- then
- (c) immersing the plaque and a counterelectrode in a first potassium hydroxide solution having a concentration in a range of about 0.05 to 10 wt.% potassium hydroxide and then
- (d) electrolytically reducing the impregnated electrode at a current density of between about 1 ma/cm.sup.2 and
A method for preparing a series of electrodes which comprises:
- (A) impregnating a porous metal plaque in an aqueous metal nitrate solution with a metal hydroxide which forms by precipitation on said plaque, to form an impregnated electrode;
- (B) immersing said impregnated electrode in an aqueous alkali metal hydroxide solution, then applying an electrical current to said impregnated electrode under conditions effective to cathodically reduce said impregnated electrode and convert nitrate ions in said electrode to ammonia;
- (C) electrolytically cycling said electrode in an aqueous alkali metal hydroxide solution;
- (D) repeating steps (A) through (C) for additional metal plaques, using the same aqueous alkali metal hydroxide solution in step (B) for each successive electrode;
- (E) replacing the aqueous alkali metal hydroxide solution used in step (b) with a fresh aqueous alkali metal hydroxide solution;
- and
- (F) repeating steps (A) through (D).
A method for installing a battery electrode which includes the steps of:
- impregnating a porous metal plaque in an aqueous metal nitrate solution with a metal hydroxide which forms by precipitation on said plaque, to form impregnated electrode;
- then immersing said impregnated electrode in an aqueous alkali metal hydroxide solution;
- then applying an electrical current to said impregnated electrode under conditions effective to cathodically reduce said impregnated electrode and convert nitrate ions in said electrode to ammonia;
- then assembling the reduced, impregnated electrode into a battery without previously electrolytically cycling said electrode.
Dependencies are inferred from the claim text.