JP2002042802A - Sealed nickel-hydrogen secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealed nickel-hydrogen secondary battery having a high capacity and a long charge/discharge cycle life. SOLUTION: The A-type sealed nickel-hydrogen secondary battery comprises a negative electrode containing a hydrogen storage alloy powder, a positive electrode containing nickel hydroxide as an active material, arranged on the negative electrode with a separator therebetween, an alkali electrolyte, and a case storing these members. The secondary battery has a capacity of 310 Wh/L or more and the hydrogen storage alloy in the negative electrode is represented by a general formula Ln1-xMxNiyTz, where Ln is lanthanoid element containing 75% or more by mass of La, M is one element selected from Mg, Ca and Sr, T is at least one element selected from Co, Mn, Al, V, etc., and x, y, z are 0.01<x<0.10, 3.4<=y<=4.8, 0.7<=z<=1.3, 4.7<=y+z<=5.5, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sealed nickel-metal hydride secondary battery having an improved negative electrode containing a hydrogen storage alloy.

[0002]

2. Description of the Related Art A sealed nickel-metal hydride secondary battery is composed of a paste-type positive electrode containing nickel hydroxide as an active material and a paste-type negative electrode containing a hydrogen-absorbing alloy with an electrode group together with an alkaline electrolyte. It is housed in a container and has a closed structure. Such sealed nickel-metal hydride secondary batteries have been widely put into practical use as operating power supplies for various electronic devices such as portable telephones and portable imaging devices.
There is a demand for higher capacity and longer life.

[0003] A sealed nickel-metal hydride secondary battery has characteristics that are governed by the balance between the negative electrode, the positive electrode, and the electrolyte. Therefore, in order to increase the capacity, it is desired to use a high-capacity, long-life hydrogen storage alloy as a negative electrode component. There has been a problem that cracks are liable to be repeatedly generated in the occlusion and release reaction, and the cycle characteristics are degraded due to the occurrence of corrosion due to the appearance of a fresh surface and the accompanying consumption of the electrolyte.

[0004] Therefore, it has been difficult to produce a sealed nickel-metal hydride secondary battery having a high energy density of 310 Wh / L or more and excellent cycle characteristics by the conventional technology.

[0005]

An object of the present invention is to provide a sealed nickel-metal hydride secondary battery having a high capacity and a long charge / discharge cycle life.

[0006]

A sealed nickel-metal hydride secondary battery according to the present invention comprises: a negative electrode containing a hydrogen storage alloy powder;
An A-type sealed nickel-metal hydride secondary battery including a positive electrode containing nickel hydroxide as an active material disposed on the negative electrode with a separator interposed therebetween, an alkaline electrolyte, and a container for storing these members, The capacity of the secondary battery is 31
0 Wh / L or more, and the hydrogen storage alloy in the negative electrode is a general formula Ln _1-x M _x Ni _y T _z (where Ln is a lanthanoid element containing 75% by mass or more of La, and M is M
g, at least one element selected from Ca and Sr, wherein T is Co, Mn, Al, V, Nb, Ta, Cr, M
o, at least one element selected from Fe, Ga, Zn, Sn, In, Cu, Si, P and B, x, y, z
Are respectively 0.01 <x <0.10, 3.4 ≦ y ≦ 4.
8, 0.7 ≦ z ≦ 1.3, 4.7 ≦ y + z ≦ 5.5).

Another sealed nickel-metal hydride secondary battery according to the present invention comprises a negative electrode containing a hydrogen storage alloy powder, a positive electrode containing nickel hydroxide as an active material and having a separator interposed therebetween, and an alkaline electrolytic cell. AA sealed nickel-metal hydride secondary battery comprising a liquid and a container for accommodating these members, wherein the capacity of the secondary battery is 230 Wh / L.
The hydrogen storage alloy in the negative electrode has a general formula of Ln _1-x M _x Ni _y T _z (where Ln is 75
M is at least one element selected from Mg, Ca and Sr, and T is C
o, Mn, Al, V, Nb, Ta, Cr, Mo, Fe,
At least one element selected from Ga, Zn, Sn, In, Cu, Si, P and B, x, y and z are respectively 0.01 <x <0.10, 3.4 ≦ y ≦ 4.8, 0.7
.Ltoreq.z.ltoreq.1.3, 4.7.ltoreq.y + z.ltoreq.5.5).

[0008] Still another sealed nickel-metal hydride secondary battery according to the present invention comprises a negative electrode containing hydrogen-absorbing alloy powder, a positive electrode containing nickel hydroxide as an active material disposed on the negative electrode with a separator interposed therebetween, and an alkaline battery. An AAA-type sealed nickel-metal hydride secondary battery comprising an electrolytic solution and a container for accommodating these members, wherein the capacity of the secondary battery is 220
Wh / L or more, and the hydrogen storage alloy in the negative electrode is represented by a general formula Ln _1-x M _x Ni _y T _z (where Ln is a lanthanoid element containing 75% by mass or more of La, and M is M
g, at least one element selected from Ca and Sr, wherein T is Co, Mn, Al, V, Nb, Ta, Cr, M
o, at least one element selected from Fe, Ga, Zn, Sn, In, Cu, Si, P and B, x, y, z
Are respectively 0.01 <x <0.10, 3.4 ≦ y ≦ 4.
8, 0.7 ≦ z ≦ 1.3, 4.7 ≦ y + z ≦ 5.5).

[0009] Still another sealed nickel-metal hydride secondary battery according to the present invention comprises a negative electrode containing a hydrogen storage alloy powder, a positive electrode containing nickel hydroxide as an active material and having a separator interposed therebetween. A square sealed nickel-metal hydride secondary battery comprising an electrolyte and a container for accommodating these members, wherein the capacity of the secondary battery is 220 Wh
/ L or more, and the hydrogen storage alloy in the negative electrode has a general formula Ln _1-x M _x Ni _y T _z (where Ln is a lanthanoid element containing 75% by mass or more of La, M is Mg, Ca
And at least one element selected from Sr and Tr, where T is Co, Mn, Al, V, Nb, Ta, Cr, Mo, F
e, Ga, Zn, Sn, In, Cu, Si, P and B
At least one element selected from the group consisting of x, y, and z is 0.01 <x <0.10, 3.4 ≦ y ≦ 4.8,
0.7 ≦ z ≦ 1.3, 4.7 ≦ y + z ≦ 5.5.)
It is characterized by being represented by

In the sealed nickel-metal hydride secondary battery according to the present invention, A type, AA type, and AAA type mean the following dimensions and forms. The A system includes those having a constant diameter of 17 mm but different lengths. The AA system includes those having a constant diameter of 14.5 mm but different lengths. The AAA system includes those having a constant diameter of 10.5 mm but different lengths.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sealed nickel-metal hydride secondary battery according to the present invention (for example, a sealed cylindrical nickel-metal hydride secondary battery) will be described below with reference to FIG.

An electrode group 5 formed by laminating a positive electrode 2, a separator 3, and a negative electrode 4 and winding them in a spiral shape is accommodated in a bottomed cylindrical container 1. The negative electrode 4 is arranged at the outermost periphery of the electrode group 5 and is in electrical contact with the container 1. The alkaline electrolyte is contained in the container 1. A circular sealing plate 7 having a hole 6 in the center is arranged at the upper opening of the container 1.
The ring-shaped insulating gasket 8 is disposed between the peripheral edge of the sealing plate 7 and the inner surface of the upper opening of the container 1, and the container 1 is formed by caulking to reduce the diameter of the upper opening inward.
The sealing plate 7 is hermetically fixed via the gasket 8. One end of the positive electrode lead 9 is connected to the positive electrode 2,
The other end is connected to the lower surface of the sealing plate 7. The positive electrode terminal 10 having a hat shape is mounted on the sealing plate 7 so as to cover the hole 6. The rubber safety valve 11
The hole 6 is disposed in a space surrounded by the sealing plate 7 and the positive electrode terminal 10. The circular holding plate 12 made of an insulating material having a hole in the center is
The projecting portion of the positive electrode terminal 10 is disposed on the reference numeral 0 so as to project from the hole of the holding plate 12. The outer tube 13 covers the periphery of the holding plate 12, the side surface of the container 1, and the periphery of the bottom of the container 1.

Next, the negative electrode 4, the positive electrode 2, the separator 3
And the electrolyte will be described.

1) Negative electrode 4 The negative electrode is represented by a general formula Ln _1-x M _x Ni _y T _z (where Ln is a lanthanoid element containing 75% by mass or more of La,
M is at least one element selected from Mg, Ca and Sr, and T is Co, Mn, Al, V, Nb, Ta, C
r, Mo, Fe, Ga, Zn, Sn, In, Cu, S
at least one element selected from i, P and B;
x, y and z are 0.01 <x <0.10 and 3.4, respectively.
≦ y ≦ 4.8, 0.7 ≦ z ≦ 1.3, 4.7 ≦ y + z ≦
5.5) is contained.

The amount of La in Ln of the above general formula is 75% by mass.
With the above, the hydrogen storage amount of the hydrogen storage alloy can be increased. The La content in Ln is 100
When the content is less than mass%, Pr, C
It is preferable to use at least two or more selected from e and Nd.

In the above general formula, x (L of M element such as Mg)
If the substitution amount with respect to n) is 0.01 mole ratio or less, it becomes difficult to suppress the progress of miniaturization of the hydrogen storage alloy during the repeated storage and release of hydrogen during the charge and discharge cycle. On the other hand, when x is 0.10 mol ratio or more, generation of a segregation phase mainly composed of these elements becomes remarkable, and the capacity of the hydrogen storage alloy may be reduced. X in a more preferable general formula is 0.03 ≦ x ≦ 0.07.

The T element of the above general formula is particularly Co, Mn,
Al is preferred.

In the above general formula, N of T element such as z (Co)
When the ratio of (i) is less than 0.7 mole ratio, it is difficult to suppress the progress of miniaturization of the hydrogen storage alloy in the repetition of hydrogen storage and release during the charge / discharge cycle. On the other hand, when z exceeds 1.3 molar ratio, not only does the cost of the hydrogen storage alloy increase, but also its capacity may decrease.

The negative electrode 4 is prepared, for example, by adding a conductive material to the hydrogen storage alloy powder, kneading the mixture with a polymer binder and water to prepare a paste, filling the paste into a conductive substrate, and drying the paste. , Formed by molding.

Examples of the polymer binder include carboxymethylcellulose, methylcellulose, sodium polyacrylate, polytetrafluoroethylene and the like.

As the conductive material, for example, carbon black or the like can be used.

Examples of the conductive substrate include a two-dimensional substrate such as a punched metal, an expanded metal, a perforated rigid plate, and a nickel net, and a three-dimensional substrate such as a felt-like metal porous body and a sponge-like metal substrate. be able to.

2) Positive Electrode 2 The positive electrode 2 has a structure in which a positive electrode material containing nickel hydroxide particles as an active material, a conductive material and a polymer binder is supported on a conductive substrate.

As the nickel hydroxide particles, for example, single nickel hydroxide particles or nickel hydroxide particles in which a metal such as zinc, cobalt, bismuth or copper is eutectic can be used. In particular, the latter positive electrode containing nickel hydroxide particles can further improve the charging efficiency in a high-temperature state.

Examples of the conductive material include metal cobalt, cobalt oxide, cobalt hydroxide and the like.

Examples of the polymer binder include carboxymethyl cellulose, methyl cellulose, sodium polyacrylate, polytetrafluoroethylene and the like.

Examples of the conductive substrate include a mesh-like, sponge-like, fiber-like, or felt-like porous metal body made of nickel, stainless steel, or nickel-plated metal.

The positive electrode 2 is prepared, for example, by adding a conductive material to nickel hydroxide particles as an active material, kneading the mixture with a polymer binder and water to prepare a paste, filling the paste into a conductive substrate, After drying, it is produced by molding.

3) Separator 3 Examples of the separator 3 include a nonwoven fabric made of polyamide fiber, a nonwoven fabric made of polyolefin fiber such as polyethylene and polypropylene, or a nonwoven fabric provided with a hydrophilic functional group.

4) Alkaline Electrolyte As the alkaline electrolyte, for example, a mixed solution of sodium hydroxide (NaOH) and lithium hydroxide (LiOH),
A mixture of potassium hydroxide (KOH) and LiOH, KOH
And a mixed solution of LiOH and NaOH.

The secondary batteries, ie, the A type, AA type and AAA type secondary batteries each have a capacity of 310 Wh / L.
As mentioned above, it is 230 Wh / L or more and 220 Wh / L or more. This capacity C (Wh / L) [volume energy density]
Is defined by the following equation:

C = (C _T × Z) / V (1) where C _T (Ah) is the theoretical capacity of the secondary battery, Z (V)
Represents the voltage of the secondary battery, and V (l) represents the volume of the secondary battery (the internal volume of the container).

The A-type sealed nickel-metal hydride secondary battery according to the present invention described above comprises a negative electrode containing hydrogen-absorbing alloy powder and a positive electrode containing nickel hydroxide as an active material disposed on the negative electrode with a separator interposed therebetween. And an alkaline electrolyte,
A sealed nickel-metal hydride secondary battery comprising a container for accommodating these members, wherein the battery has a capacity of 310 Wh / L or more, and the hydrogen storage alloy in the negative electrode has a general formula Ln _1-x M _x
Ni _y T _z (where Ln is a lanthanoid element containing 75% by mass or more of La, M is at least one element selected from Mg, Ca and Sr, and T is Co, Mn, A
1, V, Nb, Ta, Cr, Mo, Fe, Ga, Zn,
At least one element selected from Sn, In, Cu, Si, P and B, x, y and z are each 0.01 <x
<0.10, 3.4 ≦ y ≦ 4.8, 0.7 ≦ z ≦ 1.
3,4.7 ≦ y + z ≦ 5.5).

The secondary battery having such a configuration has a capacity of 310 Wh.
/ L and high charge / discharge cycle characteristics.

That is, in a nickel-metal hydride secondary battery provided with a negative electrode containing a hydrogen storage alloy, by increasing the capacity per unit volume of the negative electrode, it is possible to secure a predetermined amount or more of precharge to the positive electrode at the negative electrode. High capacity can be achieved.

In order to increase the capacity per unit volume of the negative electrode, it is necessary to increase the hydrogen storage amount of the hydrogen storage alloy contained in the negative electrode. The hydrogen storage amount of the hydrogen storage alloy can be increased by increasing the content of La having a high lipophilic property among Ln of the hydrogen storage alloy represented by the general formula (75 mass% or more).

However, when the amount of La occupied by Ln in the hydrogen storage alloy is increased, the powdering of the hydrogen storage alloy is promoted in the repetition of hydrogen storage and release during the charge / discharge cycle, and the hydrogen storage alloy is easily corroded. Become.

Accordingly, the substitution amount (x) of the M element such as Mg, which is a substitution element of Ln, of the hydrogen storage alloy represented by the above general formula is defined as 0.01 <x <0.10. Thus, it is possible to suppress the pulverization of the hydrogen storage alloy during the repeated storage and release of hydrogen during the charge / discharge cycle. Further, by defining the substitution amount (z) of a T element such as Co, which is a substitution element of Ni, of the hydrogen storage alloy represented by the general formula as 0.7 ≦ z ≦ 1.30, the charge / discharge cycle can be reduced. It is possible to suppress the pulverization of the hydrogen storage alloy in the repetition of the storage and release of hydrogen. As a result, even if a hydrogen storage alloy having an extremely large La content in Ln of 75% by mass or more according to the provisions of the substitution amounts (x) and (z) of the M element and the T element constituting these hydrogen storage alloys is used, the corrosion is prevented. Can be prevented.

Accordingly, it is possible to obtain a high-capacity A-type sealed nickel-metal hydride secondary battery having a high capacity of 310 Wh / L or more and a long charge / discharge cycle life.

Further, according to the present invention, a negative electrode containing the above-mentioned hydrogen storage alloy is provided, and has a high capacity of 230 Wh / L or more.
A high-capacity AA sealed nickel-metal hydride secondary battery having a long charge / discharge cycle life can be obtained.

According to the present invention, there is further provided a sealed AAA-type nickel-metal hydride secondary battery having a high capacity of 220 Wh / L or more and a long charge / discharge cycle life, comprising a negative electrode containing the above-mentioned hydrogen storage alloy. Obtainable.

Next, the sealed nickel-metal hydride secondary battery according to the present invention will be described in detail.

This rectangular sealed nickel-metal hydride secondary battery has an electrode group in which a positive electrode, a separator and a negative electrode are laminated in this order in a bottomed rectangular cylindrical container, and a rectangular shape is formed in the opening of the container. It has a structure in which the upper sealing plate is swaged via an insulating gasket. The capacity of this secondary battery is 220
Wh / L or more. As the positive electrode, the separator, and the negative electrode, the same ones as those of the cylindrical sealed nickel-metal hydride secondary battery are used.

According to the present invention, a rectangular sealed nickel-hydrogen secondary battery having a high capacity of 220 Wh / L or more and having a long charge / discharge cycle life, comprising a negative electrode containing the above-mentioned hydrogen storage alloy. You can get a battery.

[0045]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings.

(Examples 1 to 6) <Preparation of negative electrode> La, Ce, Pr, Nd, Mg, Ni,
Put each element of Co, Mn and Al in the arc circuit and put
^{After evacuating} to ^-4 to 10 ^-5 torr, arc discharge was performed in an argon atmosphere, and the mixture was heated and melted, and then cooled to produce a hydrogen storage alloy having the composition shown in Table 1 below.

Next, each of the hydrogen storage alloys is roughly pulverized,
Furthermore, it is pulverized by a ball mill and sieved to obtain an average particle size of 3
A 5 μm hydrogen storage alloy powder was obtained. Sodium polyacrylate was added to 100 parts by mass of each of the obtained hydrogen storage alloy powders.
5 parts by mass, carboxymethylcellulose (CMC)
12 parts by mass, 1.0 part by mass of a polytetrafluoroethylene dispersion (specific gravity 1.5, solid content 60% by mass) in terms of solid content, and 1.0 part by mass of carbon black as a conductive material were added. And 30 parts by weight of water to prepare a paste. These pastes are applied to punched metal as a conductive substrate, dried,
Further pressing was performed to produce six types of negative electrodes.

<Preparation of Positive Electrode> A mixed powder consisting of 90 parts by mass of nickel hydroxide powder and 10 parts by mass of cobalt monoxide powder was mixed with 0.3 part of carboxymethyl cellulose (CMC).
A paste was prepared by adding 0.5 parts by mass of a dispersion of polytetrafluoroethylene (specific gravity: 1.5, solid content: 60% by mass) in terms of solid content and mixing with 45 parts by mass of pure water. . Subsequently, the paste was filled in a foamed nickel substrate, dried, and then rolled by roller pressing to produce a positive electrode.

Next, a 0.2-mm-thick separator made of a nonwoven fabric made of polypropylene fiber subjected to graft polymerization was interposed between the negative electrode and the positive electrode, and spirally wound to form an electrode group. Such an electrode group has a diameter of 17.0.
After having been stored in a cylindrical container having a bottom having a diameter of 7 mm, an electrolytic solution composed of 7N potassium hydroxide and 1N lithium hydroxide was stored therein, and the structure shown in FIG. Is 4000 mAh (capacity 320 Wh /
L), a sealed cylindrical nickel-metal hydride secondary battery of 4/3 A size (total height: 67 mm) was assembled.

(Comparative Examples 1 to 14) A hydrogen storage alloy having the composition shown in Table 1 below was used, and the theoretical capacity was 2800 mAh.
(Capacity 220 Wh / L), theoretical capacity 3500 mAh
(Capacity: 280 Wh / L) and theoretical capacity: 4000 mA
A sealed cylindrical nickel-metal hydride secondary battery having a size of 4 / 3A similar to that of Example 1 except that the capacity was 320 Wh / L (height: 320 Wh / L) was assembled.

The obtained Examples 1 to 6 and Comparative Examples 1 to 1
The secondary battery of No. 6 was charged at 20 ° C. and 0.1 CmA for 15 hours, and was initially activated to be discharged at 0.2 CmA and 1.0 V, then charged at 45 ° C. for 3 A for 90 minutes, and charged at 3 A throughout the voltage. The charge / discharge for discharging to 1.0 V was repeated. In such charge and discharge, the number of charge and discharge cycles when the discharge capacity became 80% or less of the initial value was determined. The results are shown in Table 1 below.

[0052]

[Table 1]

As is apparent from Table 1, the capacity is 310.
In the nickel-metal hydride secondary battery of Wh / L or more, the substitution amount of Mg (x) when the La content in Ln is 75% by mass or more.
Examples 1 to 6 provided with a negative electrode containing a hydrogen-absorbing alloy in which 0.01 <x <0.10 and the amounts (z) of Co, Mn and Al are 0.7 ≦ z ≦ 1.3. The next battery is 330-3
It can be seen that the battery has a long charge and discharge cycle life of 50 cycles.

On the other hand, the La content in Ln is 75%.
In a secondary battery provided with a negative electrode containing less than mass% of a hydrogen storage alloy, a secondary battery having a capacity of less than 310 Wh / L (Comparative Examples 1 and 2; 220 Wh / L, Comparative Examples 4 and 5; 28)
0Wh / L), although the charge / discharge cycle life is long,
310 Wh / L or higher secondary battery (Comparative Examples 7, 8; 320
(Wh / L), 240 cycles and 170 cycles, which are markedly lower in cycle characteristics than the secondary batteries of Examples 1 to 6.

The La content in Ln is 75% by mass.
Even with the above, in a secondary battery including a negative electrode containing a hydrogen storage alloy having a substitution amount (x) of Mg of 0, a secondary battery having a capacity of less than 310 Wh / L (Comparative Example 3; 220 Wh
/ L, Comparative Example 6; 280 Wh / L) has a long charge / discharge cycle life, but a secondary battery of 310 Wh / L or more (Comparative Example 9; 320 Wh / L) has 250 cycles, It can be seen that the cycle characteristics are significantly lower than that of the secondary battery.

Further, even when the La content in Ln is 75% by mass or more, the substitution amount (x) of Mg is 0.01 <x <
A secondary battery having a capacity of 320 Wh / L and having a negative electrode containing a hydrogen storage alloy out of the range of 0.10 (Comparative Examples 10 to 10)
In the case of 12), it can be seen that the cycle characteristics are 260, 245, and 180 cycles, which are significantly lower than those of the secondary batteries of Examples 1 to 6.

Further, even when the La content in Ln is 75% by mass or more, the amount (z) of Co, Mn, and Al is 0.7%.
A secondary battery having a capacity of 320 Wh / L including a negative electrode containing a hydrogen storage alloy out of the range of ≦ z ≦ 1.3 (Comparative Example 1
3, 14) indicate that the cycle characteristics are 280 cycles and 220 cycles, which are markedly lower than those of the secondary batteries of Examples 1 to 6.

(Examples 7 to 12) <Preparation of Negative Electrode> La, Ce, Pr, Nd, Mg, Ni,
Put each element of Co, Mn and Al in the arc circuit and put
^{After evacuating} to ^-4 to 10 ^-5 torr, arc discharge was performed in an argon atmosphere, and the mixture was heated and melted, and further cooled to produce a hydrogen storage alloy having a composition shown in Table 2 below.

Next, each of the hydrogen storage alloys is roughly pulverized,
Furthermore, it is pulverized by a ball mill and sieved to obtain an average particle size of 3
A 5 μm hydrogen storage alloy powder was obtained. Sodium polyacrylate was added to 100 parts by mass of each of the obtained hydrogen storage alloy powders.
5 parts by mass, carboxymethylcellulose (CMC)
12 parts by mass, 1.0 part by mass of a polytetrafluoroethylene dispersion (specific gravity 1.5, solid content 60% by mass) in terms of solid content, and 1.0 part by mass of carbon black as a conductive material were added. And 30 parts by weight of water to prepare a paste. These pastes are applied to punched metal as a conductive substrate, dried,
Further pressing was performed to produce six types of negative electrodes.

Next, a 0.2-mm-thick separator made of a nonwoven fabric made of a polypropylene fiber subjected to graft polymerization was interposed between each of the negative electrodes and the positive electrode as in Example 1, and wound spirally to form an electrode group. Produced. After storing such an electrode group in a bottomed cylindrical container having a diameter of 14.5 mm, 7N
Of potassium hydroxide and 1N lithium hydroxide, and sealing is performed so that the theoretical capacity becomes 1
AA size sealed cylindrical nickel-metal hydride secondary battery of 600 mAh (capacity 240 Wh / L) (total height 50 m
m) was assembled.

(Comparative Examples 15 to 25) A hydrogen storage alloy having the composition shown in Table 2 below was used, and the theoretical capacity was 1200 mAh.
(Capacity: 180 Wh / L) and theoretical capacity: 1600 mA
A sealed cylindrical nickel-metal hydride secondary battery having the same AA size as in Example 7 except that the capacity was 240 h / h (240 Wh / L) was assembled.

The obtained Examples 7 to 12 and Comparative Example 15
~ 25 secondary batteries at 20 ° C and 0.1 CmA
After charging for 5 hours and performing initial activity of discharging at 0.2 CmA and 1.0 V, the battery was charged at 45 ° C. for 3 minutes at 90 A for 3 minutes.
The charge / discharge of discharging the battery to A at 1.0 A was repeated. In such charge / discharge, the discharge capacity is set to the initial value of 8
The number of charge / discharge cycles when the value became 0% or less was determined. The results are shown in Table 2 below.

[0063]

[Table 2]

As is apparent from Table 2, the capacity is 230
Wh / L or more, La content in Ln is 75% by mass or more, and Mg substitution amount (x) is 0.01 <x <0.10, C
Examples 7-1 provided with a negative electrode containing a hydrogen storage alloy in which the amounts (z) of o, Mn and Al are 0.7 ≦ z ≦ 1.3.
AA size nickel-metal hydride secondary battery of 380-43
It can be seen that the charge / discharge cycle life is as long as 0 cycles.

On the other hand, the La content in Ln is 75%.
AA with negative electrode containing less than 5% by mass of hydrogen storage alloy
Regarding the size of the secondary battery, the secondary battery having a capacity of less than 230 Wh / L (180 Wh / L) (Comparative Examples 15 and 16) has a long charge-discharge cycle life, but 230 Wh / L.
It can be seen that the cycle characteristics of the above secondary batteries (Comparative Examples 18 and 19) are 285 cycles and 205 cycles, which are significantly lower than those of the secondary batteries of Examples 7 to 12.

The La content in Ln is 75% by mass.
Even in the above, in the AA size secondary battery including the negative electrode containing the hydrogen storage alloy having the substitution amount (x) of Mg of 0, the capacity of Comparative Example 17 having a capacity of less than 230 Wh / L (180 Wh / L) is obtained. Although the charge / discharge cycle life of the secondary battery is long, the cycle characteristics of the secondary battery of Comparative Example 20 of 230 Wh / L or more are 295 cycles, which is significantly lower than that of the secondary batteries of Examples 7 to 12. Understand.

Further, even when the La content in Ln is 75% by mass or more, the substitution amount (x) of Mg is 0.01 <x <
In the AA size secondary batteries (Comparative Examples 21 to 23) each having a capacity of 240 Wh / L and having a negative electrode containing a hydrogen storage alloy out of the range of 0.10. It can be seen that the cycle characteristics are significantly lower than those of the secondary batteries of Nos. To 12.

Further, even when the La content in Ln is 75% by mass or more, the amount (z) of Co, Mn, Al is 0.7%.
In the case of a secondary battery of AA size having a capacity of 240 Wh / L (Comparative Examples 24 and 25) provided with a negative electrode containing a hydrogen storage alloy out of the range of ≦ z ≦ 1.3 (Comparative Examples 24 and 25), the number of cycles was 290 and 265. It can be seen that the cycle characteristics are significantly lower than those of the secondary batteries of Nos. To 12.

(Examples 13 to 18) <Preparation of Negative Electrode> La, Ce, Pr, Nd, Mg, Ni,
Put each element of Co, Mn and Al in the arc circuit and put
^{After evacuating} to ^-4 to 10 ^-5 torr, arc discharge was performed in an argon atmosphere, and the mixture was heated and melted, and then cooled to produce a hydrogen storage alloy having the composition shown in Table 3 below.

Next, each of the hydrogen storage alloys is roughly pulverized,
Furthermore, it is pulverized by a ball mill and sieved to obtain an average particle size of 3
A 5 μm hydrogen storage alloy powder was obtained. Sodium polyacrylate was added to 100 parts by mass of each of the obtained hydrogen storage alloy powders.
5 parts by mass, carboxymethylcellulose (CMC)
12 parts by mass, 1.0 part by mass of a polytetrafluoroethylene dispersion (specific gravity 1.5, solid content 60% by mass) in terms of solid content, and 1.0 part by mass of carbon black as a conductive material were added. And 30 parts by weight of water to prepare a paste. These pastes are applied to punched metal as a conductive substrate, dried,
Further pressing was performed to produce six types of negative electrodes.

Next, a separator having a thickness of 0.2 mm made of a nonwoven fabric made of a polypropylene fiber subjected to graft polymerization was interposed between each of the negative electrodes and the positive electrode as in Example 1, and wound spirally to form an electrode group. Produced. After storing such an electrode group in a bottomed cylindrical container having a diameter of 10.5 mm, 7N
Of potassium hydroxide and 1N lithium hydroxide, and the capacities are 7
AAA size sealed cylindrical nickel-metal hydride secondary battery with a capacity of 00 mAh (capacity 230 Wh / L) (total height 43.6
mm) was assembled.

(Comparative Examples 26 to 36) A hydrogen storage alloy having the composition shown in Table 3 below was used, and the theoretical capacity was 550 mAh.
(Capacity 180 Wh / L) and theoretical capacity 700 mAh
A sealed cylindrical nickel-metal hydride secondary battery having the same AAA size as in Example 13 except that the capacity was 230 Wh / L was assembled.

The obtained examples 13 to 18 and comparative example 2
The secondary batteries of Nos. 6 to 36 were charged at 20 ° C. and 0.1 CmA for 15 hours, and then subjected to initial activity of discharging at 0.2 CmA and 1.0 V, and then charged at 45 ° C. and 3 A for 90 minutes.
The charge / discharge in which the voltage was constantly discharged to 1.0 V at 3 A was repeated. In such charge / discharge, the discharge capacity is set to the initial value of 8
The number of charge / discharge cycles when the value became 0% or less was determined. The results are shown in Table 3 below.

[0074]

[Table 3]

As is apparent from Table 3, the capacity is 220
Wh / L or more, La content in Ln is 75% by mass or more, and Mg substitution amount (x) is 0.01 <x <0.10, C
Examples 13 to 15 provided with a negative electrode containing a hydrogen storage alloy in which the amounts (z) of o, Mn, and Al are 0.7 ≦ z ≦ 1.3.
18 AAA size nickel metal hydride rechargeable batteries
It can be seen that the battery has a long charge and discharge cycle life of 380 cycles.

On the other hand, the La content in Ln is 75%.
AA with negative electrode containing less than 5% by mass of hydrogen storage alloy
A size secondary battery having a capacity of less than 220 Wh / L (180 Wh / L) (Comparative Examples 26 and 27)
Although the charging / discharging cycle life is long, 220 Wh /
It can be seen that the cycle characteristics of the secondary batteries of L or more (Comparative Examples 29 and 30) are 250 cycles and 265 cycles, which are significantly lower than those of the secondary batteries of Examples 13 to 18.

The La content in Ln is 75% by mass.
Even in the above case, in the AAA size secondary battery including the negative electrode containing the hydrogen storage alloy having the Mg substitution amount (x) of 0, the capacity is less than 220 Wh / L (180 Wh / L).
Although the secondary battery of Comparative Example 28 has a long charge / discharge cycle life, the secondary battery of Comparative Example 31 having 220 Wh / L or more has 280 cycles, which is significantly higher than the secondary batteries of Examples 13 to 18. It turns out that becomes low.

Further, even when the La content in Ln is 75% by mass or more, the substitution amount (x) of Mg is 0.01 <x <
In the case of a secondary battery of a AAA size having a capacity of 220 Wh / L (Comparative Examples 32-34) having a negative electrode containing a hydrogen storage alloy out of the range of 0.10, 245 cycles, 230 cycles, and 170 cycles, and this Example 13 It can be seen that the cycle characteristics are significantly lower than those of the secondary batteries of Nos. 18 to 18.

Further, even when the La content in Ln is 75% by mass or more, the amount (z) of Co, Mn, and Al is 0.7% or more.
A secondary battery of a AAA size with a capacity of 220 Wh / L (comparative examples 35 and 36) including a negative electrode containing a hydrogen storage alloy out of the range of ≦ z ≦ 1.3 (comparative examples 35 and 36) had a cycle of 180 cycles.
It can be seen that the cycle characteristics are significantly lower than those of the secondary batteries of Examples 13 to 18.

(Examples 19 to 24) <Preparation of negative electrode> La, Ce, Pr, Nd, Mg, Ni,
Put each element of Co, Mn and Al in the arc circuit and put
^{After evacuating} to ^-4 to 10 ^-5 torr, arc discharge was performed in an argon atmosphere, and the mixture was heated and melted, and then cooled to produce a hydrogen storage alloy having a composition shown in Table 4 below.

Next, each of the hydrogen storage alloys is roughly pulverized,
Furthermore, it is pulverized by a ball mill and sieved to obtain an average particle size of 3
A 5 μm hydrogen storage alloy powder was obtained. Sodium polyacrylate was added to 100 parts by mass of each of the obtained hydrogen storage alloy powders.
5 parts by mass, carboxymethylcellulose (CMC)
12 parts by mass, 1.0 part by mass of a polytetrafluoroethylene dispersion (specific gravity 1.5, solid content 60% by mass) in terms of solid content, and 1.0 part by mass of carbon black as a conductive material were added. And 30 parts by weight of water to prepare a paste. These pastes are applied to punched metal as a conductive substrate, dried,
Further pressing was performed to produce six types of negative electrodes.

Next, each negative electrode, the same positive electrode as in Example 1, and a 0.2-mm-thick separator made of a nonwoven fabric made of polypropylene fiber subjected to graft polymerization were used.
An electrode group was prepared by laminating a plurality of sheets in the order of separator-positive electrode-separator-negative electrode. After storing such an electrode group in a bottomed rectangular container having a body length of 17 mm and a width of 6.1 mm, an electrolytic solution composed of 7N potassium hydroxide and 1N lithium hydroxide is accommodated, and a seal or the like is sealed. As a result, an F6 sealed square nickel-metal hydride secondary battery (total height: 48 mm) having a theoretical capacity of 850 mAh (capacity: 230 Wh / L) was assembled.

(Comparative Examples 37 to 47) A hydrogen storage alloy having the composition shown in Table 4 below was used, and the theoretical capacity was 650 mAh.
(Capacity 180 Wh / L) and theoretical capacity 850 mAh
A sealed square nickel-metal hydride secondary battery of F6 size similar to that of Example 19 except that the capacity was 230 Wh / L was assembled.

Examples 19 to 24 and Comparative Example 3
The secondary batteries of Nos. 7 to 47 were charged at 20 ° C. and 0.1 CmA for 15 hours, and then subjected to initial activity of discharging at 0.2 CmA and 1.0 V, and then charged at 45 ° C. and 3 A for 90 minutes.
The charge / discharge in which the voltage was constantly discharged to 1.0 V at 3 A was repeated. In such charge / discharge, the discharge capacity is set to the initial value of 8
The number of charge / discharge cycles when the value became 0% or less was determined. The results are shown in Table 4 below.

[0085]

[Table 4]

As is apparent from Table 4, the capacity was 220
Wh / L or more, La content in Ln is 75% by mass or more, and Mg substitution amount (x) is 0.01 <x <0.10, C
Examples 19 to 19 provided with a negative electrode containing a hydrogen storage alloy in which the amounts (z) of o, Mn and Al are 0.7 ≦ z ≦ 1.3.
24 sealed square nickel-metal hydride rechargeable batteries are 380 to 410
It can be seen that the battery has a long charge and discharge cycle life.

On the other hand, when the La content in Ln is 75%
A sealed rectangular nickel-metal hydride secondary battery provided with a negative electrode containing less than 5% by mass of a hydrogen storage alloy has a capacity of 220 Wh.
/ L (180 Wh / L) (Comparative Example 37,
38), the charge / discharge cycle life is long, but 220
In the case of the secondary batteries of Wh / L or more (Comparative Examples 40 and 41), 28
It can be seen that the cycle characteristics are significantly lower than those of the secondary batteries of Examples 19 to 24, ie, 0 cycle and 200 cycles.

The La content in Ln is 75% by mass.
Even with the above, in a sealed rectangular nickel-metal hydride secondary battery provided with a negative electrode containing a hydrogen storage alloy having a substitution amount (x) of Mg of 0, the capacity is less than 220 Wh / L (180 Wh / L).
/ L) of the secondary battery of Comparative Example 39 has a long charge / discharge cycle life, but the secondary battery of Comparative Example 42 having 220 Wh / L or more has 280 cycles, which is larger than the secondary batteries of Examples 19 to 24. It can be seen that the cycle characteristics are significantly reduced.

Further, even when the La content in Ln is 75% by mass or more, the substitution amount (x) of Mg is 0.01 <x <
In a sealed square nickel-metal hydride secondary battery (comparative examples 43 to 45) having a capacity of 230 Wh / L and having a negative electrode containing a hydrogen storage alloy out of the range of 0.10.
It can be seen that the cycle characteristics are significantly lower than those of the secondary batteries of Examples 19 to 24, ie, 0 cycle and 200 cycles.

Further, even when the La content in Ln is 75% by mass or more, the amount (z) of Co, Mn, Al is 0.7%.
A sealed square nickel-metal hydride secondary battery (comparative examples 46 and 47) having a capacity of 230 Wh / L and having a negative electrode containing a hydrogen storage alloy out of the range of ≦ z ≦ 1.3 (Comparative Examples 46 and 47) has 280 cycles,
It can be seen that the cycle characteristics are significantly lower than those of the secondary batteries of Examples 19 to 24 at 250 cycles.

[0091]

As described above, according to the present invention, a sealed nickel-metal hydride battery having a high capacity and a long charge / discharge cycle life and suitable as an operating power source for various electronic devices such as a portable telephone and a portable image pickup device. A secondary battery can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a sealed cylindrical nickel-metal hydride secondary battery according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Container, 2 ... Positive electrode, 3 ... Separator, 4 ... Negative electrode, 5 ... Electrode group, 7 ... Sealing plate, 8 ... Insulating gasket.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H028 AA01 EE01 HH00 5H050 AA07 AA08 BA14 CA03 CB17 EA10 EA23 EA24 FA17 HA02 HA19

Claims (4)

[Claims] 1. A negative electrode containing a hydrogen storage alloy powder, a positive electrode containing nickel hydroxide as an active material and having a separator interposed between the negative electrode, an alkaline electrolyte, and a container for accommodating these members. An A-type sealed nickel-metal hydride secondary battery, wherein the capacity of the secondary battery is 310 Wh / L or more, and the hydrogen storage alloy in the negative electrode is a general formula Ln _1-x M _x Ni
_y T _z (where Ln is a lanthanoid element containing 75% by mass or more of La, M is at least one element selected from Mg, Ca and Sr, and T is Co, Mn, Al,
V, Nb, Ta, Cr, Mo, Fe, Ga, Zn, S
At least one element selected from n, In, Cu, Si, P and B, x, y and z are each 0.01 <x <
0.10, 3.4 ≦ y ≦ 4.8, 0.7 ≦ z ≦ 1.3,
4.7 ≦ y + z ≦ 5.5). 2. A negative electrode containing a hydrogen storage alloy powder, a positive electrode containing nickel hydroxide as an active material disposed with a separator interposed between the negative electrode, an alkaline electrolyte, and a container for accommodating these members. AA-based sealed nickel-metal hydride secondary battery, wherein the capacity of the secondary battery is 230 Wh / L or more, and the hydrogen storage alloy in the negative electrode has a general formula of Ln _1-x M _x Ni
_y T _z (where Ln is a lanthanoid element containing 75% by mass or more of La, M is at least one element selected from Mg, Ca and Sr, and T is Co, Mn, Al,
V, Nb, Ta, Cr, Mo, Fe, Ga, Zn, S
At least one element selected from n, In, Cu, Si, P and B, x, y and z are each 0.01 <x <
0.10, 3.4 ≦ y ≦ 4.8, 0.7 ≦ z ≦ 1.3,
4.7 ≦ y + z ≦ 5.5). 3. A negative electrode containing a hydrogen storage alloy powder, a positive electrode containing nickel hydroxide as an active material and having a separator interposed therebetween, an alkaline electrolyte, and a container for accommodating these members. An AAA-type sealed nickel-metal hydride secondary battery, wherein the capacity of the secondary battery is 220 Wh / L or more, and the hydrogen storage alloy in the negative electrode is a general formula Ln _1-x M _x Ni
_y T _z (where Ln is a lanthanoid element containing 75% by mass or more of La, M is at least one element selected from Mg, Ca and Sr, and T is Co, Mn, Al,
V, Nb, Ta, Cr, Mo, Fe, Ga, Zn, S
At least one element selected from n, In, Cu, Si, P and B, x, y and z are each 0.01 <x <
0.10, 3.4 ≦ y ≦ 4.8, 0.7 ≦ z ≦ 1.3,
4.7 ≦ y + z ≦ 5.5). 4. A negative electrode containing a hydrogen storage alloy powder, a positive electrode containing nickel hydroxide as an active material disposed with a separator interposed between the negative electrode, an alkaline electrolyte, and a container for accommodating these members. A rectangular sealed nickel-metal hydride secondary battery, wherein the capacity of the secondary battery is 220 Wh / L or more, and the hydrogen storage alloy in the negative electrode is a general formula Ln _1-x M _x Ni
_y T _z (where Ln is a lanthanoid element containing 75% by mass or more of La, M is at least one element selected from Mg, Ca and Sr, and T is Co, Mn, Al,
V, Nb, Ta, Cr, Mo, Fe, Ga, Zn, S
At least one element selected from n, In, Cu, Si, P and B, x, y and z are each 0.01 <x <
0.10, 3.4 ≦ y ≦ 4.8, 0.7 ≦ z ≦ 1.3,
4.7 ≦ y + z ≦ 5.5).