Electrochemical cells having a gelled anode-electrolyte mixture

• US 4,681,698 A
• Filed: 07/28/1980
• Issued: 07/21/1987
• Est. Priority Date: 12/26/1979
• Status: Expired due to Term

• Current Assignee: Duracell Incorporated (Berkshire Hathaway Incorporated)
• Original Assignee: Duracell Incorporated (Berkshire Hathaway Incorporated)
• Inventors: Graham, Teresita O., Goodman, John T.
• Primary Examiner(s): Barr, Josephine L.
• Application Number:
  US06/173,941
• Time in Patent Office: 2,549 Days
• Field of Search: 252/500, 252/518, 252/512, 252/182.1, 252/315-317, 252/302, 252/62.2, 252/315.2, 252/315.3, 429/190, 429/212, 429/214, 429/215, 429/216, 429/217, 260/17.42, 260/17.4 GC, 260/17.4 ST, 260/17.4 CL
• US Class Current: 252/182.1
• CPC Class Codes: H01M 4/06 Electrodes for primary cells
• CPC Class Codes: H01M 4/621 Binders
• CPC Class Codes: H01M 6/22 Immobilising of electrolyte

Abstract

An electrochemical cell having an anode, a cathode and an aqueous alkaline electrolyte solution. The anode is an intimate gelled mixture of a powdered metal, an aqueous electrolyte solution and an agent capable of gelling the mixture. The agent is a material capable of absorbing water and having a carbohydrate backbone which has a water soluble side chain grafted thereon. A preferred agent is a water insoluble salt of an aqueous alkali saponified gelatinized starch having a water soluble side chain grafted thereon. The gelling of the intimate mixture of the powdered metal anode and electrolyte solution with the agent is a method of improving the discharge characteristics of the cell.

Claims

1. A method for improving the discharge characteristics of an electrochemical cell having a cathode, a powdered metal anode and an aqueous alkaline electrolyte solution comprising the step of gelling an intimate mixture of the powdered metal anode and electrolyte solution with an agent, said agent comprising a material capable of absorbing water and having a carbohydrate backbone and water soluble, ionized side chain grafted thereon;

said carbohydrate backbone and side chain being in molar ratios of from 1;

1 to 1;

19; and

said side chain being selected from the group consisting of acrylonitrile, acrylamide, acrylic acid, methyl methacrylate, acrylic acid ester, vinylacetate, N-vinyl-2-pyrrolidone, salts of alginic acid, gluconic acid, and mixtures thereof.

2. The method of claim 1 wherein said anode metal comprises zinc.

3. The method of claim 1 wherein the carbohydrate backbone comprises starch.

4. The method of claim 1 wherein the side chain has been chemically grafted to said carbohydrate.

5. A method for improving the discharge characteristics of an electrochemical cell having a cathode, a powdered metal anode and an aqueous alkaline electrolyte solution comprising the step of gelling an intimate mixture of the powdered metal anode and electrolyte solution with an agent, said agent comprising a water insoluble salt of an aqueous, alkali saponified material comprising a gelatinized starch backbone having water soluble side chains grafted thereon and containing gealtinized starch and saponified side chains in molar ratios of from about 1:

1 to 1;

9; and

said side chain being selected from the group consisting of acrylonitrile, acrylamide, acrylic acid, methyl methacrylate, acrylic acid ester, vinylacetate, N-vinyl-2-pyrrolidone, salts of alginic acid, gluconic acid, and mixtures thereof.

6. The method of claim 5 wherein said grafted side chains comprise acrylonitrile.

7. The method of claim 5 wherein the water insoluble salt comprises an alkaline salt.