Positive electrode active material for alkaline storage battery, positive electrode for alkaline storage battery, alkaline storage battery, and method for manufacturing positive electrode active material for alkaline storage battery

Patent metadata

Field	Value
Publication number	US-9276258-B2
Application number	US-65880505-A
Country	US
Kind code	B2
Filing date	Jul 15, 2005
Priority date	Jul 30, 2004
Publication date	Mar 1, 2016
Grant date	Mar 1, 2016

Abstract

There are provided a positive electrode active material for an alkaline storage battery, a positive electrode for an alkaline storage battery, and an alkaline storage battery each of which has an excellent output characteristics and also has an excellent self-discharge characteristic and an excellent cycle lifetime characteristic. The positive electrode active material for an alkaline storage battery according to the present invention has nickel hydroxide particles each containing at least magnesium in a solid solution state and a cobalt compound layer coating the surface of each of the nickel hydroxide particles. Among them, the cobalt compound layer contains cobalt having an average valence of not less than 2.6 and not more than 3.0 and also contains sodium at a proportion of less than 0.10 wt % to the total weight of the cobalt compound layer. The positive electrode active material for an alkaline storage battery according to the present invention has a conductivity smaller than 1.0×10 −5 S/cm in a state pressurized at 39.2 MPa.

First claim

The invention claimed is:

1. A positive electrode active material powder for an alkaline storage battery, the positive electrode active material powder comprising:
nickel hydroxide particles each containing at least magnesium in a solid solution state; and
a cobalt compound layer coating a surface of each of the nickel hydroxide particles,
wherein the cobalt compound layer contains cobalt having an average valence of not less than 2.6 and not more than 3.0, contains sodium at a proportion of less than 0.10 wt % to a total weight of the cobalt compound layer,
a cobalt compound composing the cobalt compound layer primarily contains cobalt oxyhydroxide and a peak half width of the (110) plane of the cobalt compound which is located in the vicinity of 2θ=64° to 67° in X-ray diffraction using a CuKα beam is not more than 1.5°, and
the positive electrode active material powder has a conductivity of the cobalt compound layer smaller than 1.0×10 −5 S/cm, the conductivity being measured in a state in which the positive electrode active material powder is pressurized at 39.2 MPa.

2. A positive electrode active material powder for an alkaline storage battery according to claim 1 , wherein a proportion of the magnesium contained in the solid solution state in each of the nickel hydroxide particles is not less than 2 mol % and not more than 10 mol % to all metal elements contained in each of the nickel hydroxide particles.

3. A positive electrode active material powder for an alkaline storage battery according to claim 1 , containing 1.0 wt % or less of a sulfate group.

4. A positive electrode active material powder for an alkaline storage battery according to claim 1 , wherein a peak half width of the (101) plane of each of the nickel hydroxide particles which is located in the vicinity of 2θ=37° to 40° in X-ray diffraction using a CuKα beam is more than 0.7° and not more than 1.2°.

5. A positive electrode active material powder for an alkaline storage battery according to claim 1 , having an average particle diameter of not less than 5 μm and not more than 20 μm.

6. A positive electrode active material powder for an alkaline storage battery according to claim 1 , wherein the cobalt compound layer has an average thickness of not more than 0.20 μm.

7. A positive electrode active material powder for an alkaline storage battery according to claim 1 , wherein a specific surface area measured by a BET method based on nitrogen gas adsorption is not less than 8.0 m 2 /g and not more than 1.8×10 m 2 /g.

8. A positive electrode active material powder for an alkaline storage battery according to claim 1 , which is produced by supplying an aqueous solution containing cobalt ions into an aqueous solution containing nickel hydroxide particles, while supplying an aqueous sodium hydroxide solution into the aqueous solution containing the nickel hydroxide particles to maintain the pH thereof in a range of 11.5 to 13.5 and also supplying air thereinto.

9. A positive electrode active material powder for an alkaline storage battery according to claim 8 , which is produced by adjusting a concentration of oxygen dissolved in the aqueous solution containing the nickel hydroxide particles to a value of not less than 1.0 mg/l and not more than 1.5×10 mg/l by using the air supplied into the aqueous solution containing the nickel hydroxide particles.

10. A positive electrode for an alkaline storage battery containing:
a positive electrode active material powder for an alkaline storage battery as recited in claim 1 .

11. The positive electrode for an alkaline storage battery according to claim 10 , containing, in addition to the positive electrode active material powder:
metal cobalt particles; and
yttrium oxide particles.

12. The positive electrode for an alkaline storage battery according to claim 11 , wherein the metal cobalt particles are contained at a proportion of 2 to 7 parts by weight to 100 parts by weight of the positive electrode active material powder.

13. The positive electrode for an alkaline storage battery according to claim 11 , wherein the yttrium oxide particles are contained at a proportion of 0.5 to 3 parts by weight to 100 parts by weight of the positive electrode active material powder.

14. An alkaline storage battery comprising:
a positive electrode for an alkaline storage battery as recited in claim 10 .

Assignees

• Sakamoto Hiroyuki
• Ohkawa Kazuhiro
• Yuasa Shinichi
• Toyota Motor Co Ltd

Inventors

• Sakamoto Hiroyuki
• Ohkawa Kazuhiro
• Yuasa Shinichi

Classifications

• C01G53/82

  Compounds containing nickel, with or without oxygen or hydrogen, and containing two or more other elements · CPC title

• Y02E60/10

  Energy storage using batteries · CPC title

• H01M4/383

  Hydrogen absorbing alloys · CPC title

• C01P2006/40

  Electric properties · CPC title

• H01M4/32 Primary

  Nickel oxide or hydroxide electrodes · CPC title