Nickel-metal hydride battery

Patent metadata

Field	Value
Publication number	US-10658660-B2
Application number	US-201715712078-A
Country	US
Kind code	B2
Filing date	Sep 21, 2017
Priority date	Sep 26, 2016
Publication date	May 19, 2020
Grant date	May 19, 2020

Abstract

A nickel-metal hydride battery is provided with a positive electrode and a negative electrode including hydrogen absorbing alloys. The hydrogen absorbing alloys of the negative electrode include a first hydrogen absorbing alloy and a second hydrogen absorbing alloy having a higher hydrogen equilibrium dissociation pressure than the first hydrogen absorbing alloy. Each hydrogen absorbing alloy includes an element A having high affinity for hydrogen and an element B having low affinity for hydrogen. The ratio of a substance amount of the element B to a substance amount of the element A is greater in the second hydrogen absorbing alloy than the first hydrogen absorbing alloy.

First claim

The invention claimed is:

1. A nickel-metal hydride battery comprising:
a positive electrode; and
a negative electrode including hydrogen absorbing alloys, wherein:
a capacity of the negative electrode includes a discharge reserve that is a capacity exceeding a capacity of the positive electrode,
the hydrogen absorbing alloys of the negative electrode include a first hydrogen absorbing alloy and a second hydrogen absorbing alloy having a higher hydrogen equilibrium dissociation pressure than the first hydrogen absorbing alloy,
each hydrogen absorbing alloy includes an element A having high affinity for hydrogen and an element B having low affinity for hydrogen, wherein when a ratio of a substance amount of the element B to a substance amount of the element A is referred to as an AB ratio, the AB ratio of the second hydrogen absorbing alloy is greater than an AB ratio of the first hydrogen absorbing alloy,
a proportion of the first hydrogen absorbing alloy in all of the hydrogen absorbing alloys is less than a sum of a proportion of the discharge reserve in the entire capacity of the negative electrode and a proportion of a capacity of a portion corresponding to a lower limit value of 0% or greater of a charge rate of the positive electrode in the negative electrode in the entire capacity of the negative electrode,
the first hydrogen absorbing alloy and the second hydrogen absorbing alloy are AB5-type hydrogen absorbing alloys,
a main element of the element A is La, and a main element of the element B is Ni, and
6.9≤(Y/X) R≤7.1 is satisfied, where “X” represents a theoretical positive electrode capacity, “Y” represents a theoretical negative electrode capacity, and “R” represents the AB ratio.

2. The nickel-metal hydride battery according to claim 1 , wherein the AB ratio of the second hydrogen absorbing alloy is greater than the AB ratio of the first hydrogen absorbing alloy by at least 0.1.

3. The nickel-metal hydride battery according to claim 1 , wherein a cobalt content of the second hydrogen absorbing alloy is greater than a cobalt content of the first hydrogen absorbing alloy.

4. The nickel-metal hydride battery according to claim 1 , wherein the proportion of the first hydrogen absorbing alloy to the all of the hydrogen absorbing alloys is greater than or equal to the proportion of the discharge reserve in the capacity of the negative electrode.

5. The nickel-metal hydride battery according to claim 1 , wherein the lower limit value is a lower limit value of the charge rate of the positive electrode when the nickel-metal hydride battery is used as a power source.

6. The nickel-metal hydride battery according to claim 1 , wherein the lower limit value is 40%.

7. The nickel-metal hydride battery according to claim 1 , wherein a difference in hydrogen equilibrium dissociation pressure at 45° C. between the second hydrogen absorbing alloy and the first hydrogen absorbing alloy is 0.01 MPa or greater.

8. The nickel-metal hydride battery according to claim 1 , wherein the positive electrode and the negative electrode are accommodated in a resin case.

9. The nickel-metal hydride battery according to claim 1 , wherein
at least one of a product of a length of axis a of a unit lattice of the first hydrogen absorbing alloy and the proportion of the first hydrogen absorbing alloy in all of the hydrogen absorbing alloys and a product of a length of axis b of the unit lattice of the first hydrogen absorbing alloy and the proportion of the first hydrogen absorbing alloy in all of the hydrogen absorbing alloys is 0.7 or greater and 1.4 or less.

10. A nickel-metal hydride battery comprising:
a positive electrode; and
a negative electrode including hydrogen absorbing alloys, wherein:
a capacity of the negative electrode includes a discharge reserve that is a capacity exceeding a capacity of the positive electrode,
the hydrogen absorbing alloys of the negative electrode include a first hydrogen absorbing alloy and a second hydrogen absorbing alloy having a higher hydrogen equilibrium dissociation pressure than the first hydrogen absorbing alloy,
each hydrogen absorbing alloy includes an element A having high affinity for hydrogen and an element B having low affinity for hydrogen, wherein when a ratio of a substance amount of the element B to a substance amount of the element A is referred to as an AB ratio, the AB ratio of the second hydrogen absorbing alloy is greater than an AB ratio of the first hydrogen absorbing alloy,
a proportion of the first hydrogen absorbing alloy in all of the hydrogen absorbing alloys is less than a sum of a proportion of the discharge reserve in the entire capacity of the negative electrode and a proportion of a capacity of a portion corresponding to a lower limit value of 0% or greater of a charge rate of the positive electrode in the negative electrode in the entire capacity of the negative electrode, and
the proportion of the first hydrogen absorbing alloy in all of the hydrogen absorbing alloys is less than the proportion of the capacity of the discharge reserve in the capacity of the negative electrode.

Assignees

• Primearth Ev Energy Co Ltd

Inventors

• Muraki Suguru
• Sakito Yuki
• Sakamoto Hiroyuki

Classifications

• H01M4/385 Primary

  of the type LaNi5 · CPC title

• C22C19/03

  based on nickel · CPC title

• H01M10/30 Primary

  Nickel accumulators (H01M10/34 takes precedence) · CPC title

• H01M4/362

  Composites · CPC title

• H01M4/242

  Hydrogen storage electrodes · CPC title