Production of zinc pellets

• US 5,578,183 A
• Filed: 05/11/1995
• Issued: 11/26/1996
• Est. Priority Date: 05/11/1995
• Status: Expired due to Term

• Current Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Cooper, John F.
• Primary Examiner(s): Valentine, Donald R.
• Application Number:
  US08/439,388
• Time in Patent Office: 565 Days
• Field of Search: 205/64, 205/74, 205/78, 205/109, 205/111
• US Class Current: 205/64
• CPC Class Codes: C25C 1/16 of zinc, cadmium or mercury
• CPC Class Codes: C25C 5/02 from solutions
• CPC Class Codes: H01M 12/06 with one metallic and one gaseous electrode
• CPC Class Codes: H01M 2004/024 Insertable electrodes
• CPC Class Codes: H01M 4/02 Electrodes composed of, or comprising, active material
• CPC Class Codes: H01M 6/5077 Regeneration of reactants or electrolyte
• CPC Class Codes: H01M 8/06 Combination of fuel cells with means for production of reactants or for treatment of residues regenerative fuel cells H01M8/18
• CPC Class Codes: H01M 8/225 Fuel cells in which the fuel is based on materials comprising particulate active material in the form of a suspension, a dispersion, a fluidised bed or a paste
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

Uniform zinc pellets are formed for use in batteries having a stationary or moving slurry zinc particle electrode. The process involves the cathodic deposition of zinc in a finely divided morphology from battery reaction product onto a non-adhering electrode substrate. The mossy zinc is removed from the electrode substrate by the action of gravity, entrainment in a flowing electrolyte, or by mechanical action. The finely divided zinc particles are collected and pressed into pellets by a mechanical device such as an extruder, a roller and chopper, or a punch and die. The pure zinc pellets are returned to the zinc battery in a pumped slurry and have uniform size, density and reactivity. Applications include zinc-air fuel batteries, zinc-ferricyanide storage batteries, and zinc-nickel-oxide secondary batteries.

Claims

1. An electrochemical process for producing porous zinc pellets for use in a zinc-air battery, comprising:

depositing zinc particles by cathodic deposition onto a substrate, wherein the particles do not permanently adhere to the substrate;

removing the zinc particles from the substrate;

mechanically compressing the particles; and

forming zinc pellets.

2. A process as recited in claim 1, wherein depositing the particles is carried out such that the particles have a morphology selected from the group consisting of mossy, dendritic, and bulbous.

3. A process as recited in claim 1, wherein depositing the particles is carried out such that the particles are deposited on an array of sheet electrodes.

4. A process as recited in claim 3, wherein the array of electrodes is inclined from the vertical position such that the cathodically polarized sides face upward.

5. A process as recited in claim 1, wherein removing particles is carried out by a process selected from the group consisting of the action of gravity, the natural or forced convection of electrolyte, and mechanical action.

6. A process as recited in claim 1, wherein compressing particles is carried out using a roller.

7. A process as recited in claim 6, wherein forming pellets is carried out by a process selected from the group consisting of using a toothed wheel and using a chopping blade.

8. A process as recited in claim 1, wherein compressing particles and forming pellets is carried out using a punch and die.

9. A process as recited in claim 1, wherein compressing particles and forming pellets is carried out using a moving perforated belt and toothed roller.

10. A process as recited in claim 9, wherein the perforated belt is cathodically polarized.

11. A process as recited in claim 1, wherein the pellets are about 0.2 mm to about 1.5 mm in size.