JP2000058106A - Manufacture of nickel-hydrogen secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve high-temperature shelf characteristic by assembling a battery provided with a separator interposed between a positive electrode and a negative electrode containing a hydrogen storage alloy and made of a sheet containing polyolefin fibers graft-copolymerized with a hydrophilic vinyl monomer, and conducting initial charging for the battery at a specific temperature. SOLUTION: This nickel-hydrogen secondary battery preferably uses a rate earth element-Ni hydrogen storage alloy with a Mn content of 0.6-2.6 wt.%, more preferably in the range of the Mn content of 1.1-1.5 wt.%. The rare earth component is preferably made of at least one or more kinds of elements selected from among La, Pr, Ce and Nd. After the nickel secondary battery is assembled, it is subjected to initial charging at the charging temperature range of 40-100 deg.C. All the more preferable range of the initial charging temperature is 70-90 deg.C. Although it is sufficient that the charging temperature be set to such a temperature only in the initial stage, the temperature may be set over the whole period, and aging may be applied before conducting the initial charging.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a nickel-metal hydride secondary battery having an improved initial charging step.

[0002]

2. Description of the Related Art A nickel-metal hydride secondary battery in which an electrode containing a hydrogen storage alloy which reversibly absorbs and releases hydrogen is used as a negative electrode, and an electrode containing nickel hydroxide is used as a positive electrode, uses an electrode containing cadmium as a negative electrode. Low pollution and clean compared to the nickel cadmium secondary battery used. Nickel-metal hydride secondary batteries have attracted attention as power sources for portable devices, notebook computers, and electric vehicles because of their higher energy density than nickel-cadmium secondary batteries.

[0003] With the expansion of applications, nickel-metal hydride rechargeable batteries have been subjected to severe conditions such as being left in a discharge state for a long time in electronic equipment or being stored at high temperatures for a long time. The number of cases being put is increasing. In order to maintain excellent charge / discharge characteristics even under such conditions, it is desired that nickel-metal hydride secondary batteries have improved storage characteristics at high temperatures.

Japanese Patent Application Laid-Open No. Hei 6-215765 discloses that an electrode group is produced between a negative electrode containing a hydrogen storage alloy and yttrium oxide and a nickel positive electrode, with a separator formed by sulfonating a polypropylene nonwoven fabric interposed therebetween. A nickel-hydrogen secondary battery containing an alkaline electrolyte in a container is disclosed.

[0005]

However, when this secondary battery is stored or left in a high-temperature environment or the like, there is a problem that the open circuit voltage is reduced and the discharge characteristics are impaired.

An object of the present invention is to provide a method for manufacturing a nickel-metal hydride secondary battery having improved high-temperature storage characteristics.

[0007]

A method for manufacturing a nickel-metal hydride secondary battery according to the present invention is characterized in that a hydrophilic vinyl monomer is interposed between a positive electrode and a negative electrode containing a hydrogen storage alloy, and is graft-copolymerized. It is characterized by comprising a step of assembling a nickel-metal hydride secondary battery provided with a separator made of a sheet containing polyolefin-based fibers, and a step of initially charging the secondary battery at 40 to 100 ° C.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an example of a nickel-metal hydride secondary battery (for example, a cylindrical nickel-metal hydride secondary battery) manufactured by the method of the present invention will be described with reference to FIG.

A positive electrode 2 is placed in a bottomed cylindrical metal container 1.
An electrode group 5 produced by spirally winding the anode and the negative electrode 4 with the separator 3 interposed therebetween is housed. 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 first metal 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 sealing plate is formed on the container 1 by caulking to reduce the diameter of the upper opening inward. 7 is hermetically fixed via the gasket 8. The positive electrode lead 9 is
One end is connected to the positive electrode 2 and the other end is connected to the lower surface of the sealing plate 7. The positive electrode terminal 10 having a hat shape is attached on the sealing plate 7 so as to cover the hole 6. A rubber safety valve 11 is disposed so as to close the hole 6 in a space surrounded by the sealing plate 7 and the positive electrode terminal 10. A circular holding plate 12 made of an insulating material having a hole in the center is arranged on the positive electrode terminal 10 such that a protrusion of the positive electrode terminal 10 projects from the hole of the holding plate 12. The outer tube 13 is provided with the holding plate 12.
, The side surface of the container 1 and the bottom peripheral edge of the container 1.

Hereinafter, a method for manufacturing a nickel-metal hydride secondary battery according to the present invention will be described.

(First step) An electrode group is prepared by interposing a separator between the positive electrode and the negative electrode, and the electrode group and the alkaline electrolyte are accommodated in a container and sealed to form an unprimed nickel hydride battery. Assemble the next battery.

The positive electrode, negative electrode, separator and alkaline electrolyte will be described.

1) Positive electrode This positive electrode contains nickel oxide and at least one selected from metallic cobalt and a cobalt compound.

The positive electrode is prepared by kneading, for example, nickel oxide powder, at least one powder selected from metallic cobalt and a cobalt compound, and a binder in the presence of water to prepare a paste. Is charged into a current collector, dried, and roll-formed.

Examples of the nickel oxide powder include nickel hydroxide powder. As the nickel hydroxide powder, for example, a powder made of nickel hydroxide or a nickel hydroxide powder in which zinc and cobalt are eutectic can be used. The latter positive electrode containing nickel hydroxide powder can improve charge efficiency and charge / discharge cycle characteristics in a high temperature state.

Examples of the cobalt compound include cobalt hydroxide, cobalt monoxide, dicobalt trioxide and the like. At least one selected from the cobalt compound and the metal cobalt can be added to the paste in the form of the powder as described above, or by being attached to the surface of the nickel oxide powder in a layered manner.

Examples of the binder include fluororesins (eg, polytetrafluoroethylene), carboxymethylcellulose, methylcellulose, polyacrylates (eg, sodium polyacrylate), hydroxymethylcellulose, polyvinyl alcohol, and the like. it can.

Examples of the current collector include a net-like, sponge-like, fibrous, and felt-like conductive substrate made of an alkali-resistant material such as nickel, stainless steel, and nickel-plated resin.

2) Negative electrode This negative electrode contains a hydrogen storage alloy.

The negative electrode is prepared by kneading a hydrogen storage alloy powder, a conductive material, a binder, and water to prepare a paste, filling the paste into a conductive substrate, drying, and then forming the paste. It is manufactured by

The hydrogen storage alloy is not particularly limited, as long as it can store hydrogen electrochemically generated in an electrolytic solution and can easily release the stored hydrogen during discharge. For example, LaNi ₅ , MmNi
₅ (Mm is misch metal), LmNi ₅ (Lm is La
At least one element selected from the group consisting of rare earth elements containing Al), Mn, Co, Ti, Cu,
Examples thereof include a multi-element-based material substituted with an element such as Zn, Zr, Cr, and B, a TiNi-based material, and a TiFe-based material.

In particular, the Mn content is 0.6 to 2.6% by weight.
It is preferable to use a rare earth-Ni-based hydrogen storage alloy. The reason why the Mn content in the hydrogen storage alloy is defined in the above range is as follows. When the Mn content is less than 0.6% by weight, corrosion or oxidation is likely to occur in the hydrogen storage alloy. On the other hand, the Mn
If the content exceeds 2.6% by weight, a large amount of Mn may be eluted from the hydrogen storage alloy into the alkaline electrolyte at a high temperature. When the elution of Mn occurs, the hydrogen storage alloy is oxidized, and the eluted Mn precipitates on the separator,
This causes an increase in internal resistance and a decrease in open circuit voltage. Therefore, if the Mn content exceeds 2.6% by weight, the discharge capacity may decrease when stored in a high-temperature environment, and the high-temperature storage characteristics may decrease. A more preferable range of the Mn content is 1.1 to 1.5% by weight.

In the rare earth-Ni hydrogen storage alloy having a Mn content of 0.6 to 2.6% by weight, the rare earth component comprises at least one element selected from La, Pr, Ce and Nd. Is preferred. Further, a part of Ni is replaced with Co, Mn, Al, Fe, Ti, Zr, Zn, C
It may be substituted with at least one selected from r and B. As a substitution element, Co, Mn, and Al are preferable from the viewpoint of preventing corrosion of rare earth components in the hydrogen storage alloy.

As the rare earth-Ni-based hydrogen storage alloy having a Mn content of 0.6 to 2.6% by weight, the general formula L
mNi _w Co _x Al _{y M} n _z (where Lm is La, P
At least one element selected from r, Ce and Nd, and the atomic ratios w, x, y and z are each 3.30.
≦ w ≦ 4.50, 0.50 ≦ x ≦ 1.10, 0.20 ≦
y ≦ 0.50, 0.05 ≦ z ≦ 0.20, and the sum thereof is represented by 4.90 ≦ w + x + y + z ≦ 5.50). The atomic ratio w,
More preferable values of x, y and z are respectively 3.80 ≦ w
≤4.20, 0.70≤x≤0.90, 0.30≤y≤
0.40, 0.08 ≦ z ≦ 0.130, and the total value is 5.00 ≦ w + x + y + z ≦ 5.20.

The negative electrode desirably contains a rare earth-based additive comprising at least one selected from a rare earth element simple substance and a rare earth element compound in a paste. As the rare earth element, at least one element selected from Y, Yb and Er can be used. As the rare earth element compound, for example, yttrium oxide (Y ₂ O
₃ ), ytterbium oxide (Yb ₂ O ₃ ), and erbium oxide (Er ₂ O ₃ ).

The amount of the rare earth-based additive is preferably in the range of 0.1 to 10 parts by weight in terms of rare earth element based on 100 parts by weight of the hydrogen storage alloy powder. This is due to the following reasons. The amount of addition is 0.
If the amount is less than 1 part by weight, it may be difficult to improve the high-temperature storage characteristics. On the other hand, if the addition amount exceeds 10 parts by weight, the amount of the hydrogen storage alloy powder per unit volume of the negative electrode may decrease, and a large discharge capacity may not be obtained. A more preferred range for the amount is 0.2 to 2 parts by weight.

Examples of the conductive material include carbon black, graphite and the like.

Examples of the binder include polyacrylates such as sodium polyacrylate and potassium polyacrylate, fluorine resins such as polytetrafluoroethylene (PTFE), and carboxymethyl cellulose (C).
MC) and the like.

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; a felt-like metal porous body;
Examples include a three-dimensional substrate such as a sponge-like porous metal body.

3) Separator The separator comprises a sheet containing polyolefin fibers onto which a vinyl monomer having a hydrophilic property is graft-copolymerized.

Examples of the sheet containing the polyolefin-based fiber include a nonwoven fabric containing the polyolefin-based fiber, a woven fabric containing the fiber, or a composite sheet made of the nonwoven fabric and the woven fabric. The nonwoven fabric is produced by, for example, a dry method, a wet method, a spun bond method, a melt blow method, or the like. Of these methods,
The spun bond method and the melt blow method can produce a nonwoven fabric having a small fiber diameter, and thus are advantageous in preventing short circuit between the positive electrode and the negative electrode.

As the polyolefin fiber, a polyolefin single fiber, a core-sheath composite fiber in which a polyolefin fiber different from the above-mentioned polyolefin fiber is coated on a core material made of the polyolefin fiber, and polyolefin fibers different from each other are circularly joined. And the like. Examples of the polyolefin include polyethylene, polypropylene, and a copolymer resin of ethylene and / or propylene with butene.

Examples of the hydrophilic vinyl monomer include acrylic acid monomers, methacrylic acid monomers, monomers of esters of acrylic acid and methacrylic acid, vinylpyridine monomers, vinylpyrrolidone monomers, styrenesulfonic acid monomers, styrene monomers and the like. Examples thereof include a vinyl monomer having a functional group capable of forming a salt by directly reacting with an acid or a base, and a vinyl monomer having a functional group capable of forming a salt by hydrolysis. Among the vinyl monomers, acrylic acid monomers are preferred.

The graft copolymerization ratio of the hydrophilic vinyl monomer in the separator is preferably in the range of 0.2 to 2.0 meq / g in terms of ion exchange capacity.

The separator may contain a polyolefin fiber in which a vinyl monomer having a hydrophilic property is not graft-copolymerized.

4) Alkaline Electrolyte Examples of the alkaline electrolyte include a mixture of potassium hydroxide, sodium hydroxide and lithium hydroxide, and a mixture of potassium hydroxide and lithium hydroxide.

(Second Step) The charging temperature of the secondary battery is set to 4
First charge at 0 to 100 ° C.

The charging temperature may be set to such a temperature only in the initial stage, but may be set to the above temperature over the entire period. The initial charging temperature is limited to the above range for the following reason. If the initial charge temperature is lower than 40 ° C., it may be difficult to improve high-temperature storage characteristics. On the other hand, when the initial charge temperature exceeds 100 ° C., the hydrogen storage alloy of the negative electrode and battery components such as a safety valve may be deteriorated by heat. A more preferable range of the initial charging temperature is 70C to 90C.

Aging may be performed before the first charge.

As described above in detail, according to the method for producing a nickel-metal hydride secondary battery according to the present invention, a polyolefin in which a hydrophilic vinyl monomer is graft-copolymerized between a positive electrode and a negative electrode containing a hydrogen storage alloy. By assembling a nickel-metal hydride secondary battery having a separator made of a sheet containing a system fiber and performing initial charging at 40 to 100 ° C., the high-temperature storage characteristics can be significantly improved. When a nickel-metal hydride secondary battery is stored in a high-temperature environment, self-discharge tends to proceed in relation to a negative electrode containing a hydrogen storage alloy. Since the separator has high hydrophilicity, it can suppress permeation of hydrogen necessarily released from the negative electrode at a high temperature. As a result, the reduction reaction of the positive electrode by the hydrogen can be suppressed, so that the self-discharge at a high temperature can be suppressed. Further, by performing the initial charge at 40 to 100 ° C., the overdischarge characteristics of the positive electrode can be improved. Therefore, the nickel-hydrogen secondary battery manufactured by the method of the present invention can suppress the progress of the self-discharge reaction at a high temperature and can improve the overdischarge characteristics of the positive electrode. Can be suppressed, and the high-temperature storage characteristics can be improved.

In the production method according to the present invention, when the hydrogen storage alloy contains Mn, the Mn content is set to 0.6 to 2.
6% by weight, when stored under high temperature,
Since Mn can be suppressed from being eluted from the hydrogen storage alloy, and increase in internal resistance and decrease in open circuit voltage can be suppressed, a decrease in discharge capacity under a high-temperature environment can be further suppressed. High temperature storage characteristics can be further improved.

In the manufacturing method according to the present invention, the negative electrode contains at least one rare earth-based additive selected from a single element of a rare earth element and a compound of a rare earth element, whereby the high-temperature storage characteristics can be further improved.

That is, the additive is dissolved in the alkaline electrolyte, and is deposited on the surface of the hydrogen storage alloy at the time of the first charge to form a protective film. The additive has low solubility in an alkaline electrolyte at room temperature. Therefore, according to the initial charge at room temperature, the formation amount of the protective film is reduced, so that the hydrogen storage alloy is corroded (oxidized) by the alkaline electrolyte and the high-temperature storage characteristics are lowered.

40 to 100 ° C. as in the method according to the invention
By performing the initial charge in, the dissolution of the additive in the alkaline electrolyte can be promoted, and a protective film can be sufficiently formed on the surface of the alloy from the beginning of the cycle. Corrosion due to the alkaline electrolyte can be suppressed, and high-temperature storage characteristics can be improved. Further, since the protective film can suppress the elution of Mn from the hydrogen storage alloy containing Mn at a high temperature, the high temperature storage of the nickel-hydrogen secondary battery including the negative electrode containing the hydrogen storage alloy containing Mn can be suppressed. Characteristics can be greatly improved.

Further, when a negative electrode containing a hydrogen storage alloy containing Mn is used, the Mn content of the alloy is set to 0.6.
To 2.6% by weight, and by including the rare earth additive in the negative electrode, it is possible to suppress corrosion of the hydrogen storage alloy by an alkaline electrolyte at a high temperature, and to reduce the amount of the hydrogen storage alloy from the hydrogen storage alloy. Since the amount of Mn eluted can be significantly reduced, the high-temperature storage characteristics of a nickel-metal hydride secondary battery including a negative electrode containing a hydrogen storage alloy containing Mn can be drastically improved.

[0046]

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

Example 1 <Preparation of Positive Electrode> A mixture of 90 parts by weight of nickel hydroxide particles and 10 parts by weight of cobalt monoxide particles was mixed with 0.25 parts by weight of carboxymethyl cellulose and 0.25 parts by weight of polyacrylic acid as a binder. A paste was prepared by adding 3 parts by weight of polytetrafluoroethylene and further adding water and kneading. This paste was filled into a nickel fiber substrate having a thickness of 1.1 mm and a porosity of 95%, dried, and pressed with a roller press to produce a paste-type nickel positive electrode.

<Preparation of Negative Electrode> LmNi _3.85 Co _0.6 Mn
_0.25 The composition of Al _0.3 (where, Lm is, La 80 wt%, Pr is 4.1 wt%, Ce 2.0 wt% and Nd
Is 13.9% by weight.
100 parts by weight of a hydrogen-absorbing alloy powder composed of 3.2% by weight) and 2.5 parts by weight of solid dispersion of polytetrafluoroethylene dispersion (specific gravity 1.5, solid content 60% by weight). , 0.125 parts by weight of carboxymethylcellulose (CMC), 1 part by weight of carbon powder and 50 parts by weight of water to prepare a paste. afterwards,
The paste was applied to a punched metal, dried, and pressed to produce a paste-type hydrogen storage alloy negative electrode.

<Preparation of Separator> A nonwoven fabric having a basis weight of 50 g / m ² and a thickness of 0.20 mm was prepared from a long polypropylene fiber having a fiber diameter of 10 μm by a spun bond method. The nonwoven fabric was immersed in an aqueous acrylic acid solution, and then irradiated with ultraviolet rays to graft copolymerize the acrylic acid monomer. The non-woven fabric was washed to remove unreacted acrylic acid, and then dried to produce a separator having a potassium ion exchange capacity of 0.7 meq / g determined by a titration method.

<Preparation of Electrode Group> An electrode group was prepared by interposing the separator between the positive electrode and the negative electrode and spirally winding the separator. After the obtained electrode group was housed in a bottomed cylindrical metal container, an alkaline electrolyte composed of 7N potassium hydroxide and 1N lithium hydroxide was housed in the container, and each member such as a metal lid was Was used to assemble an AA-size cylindrical nickel-metal hydride secondary battery.

Example 2 The composition of the hydrogen storage alloy was LmNi
_A cylindrical nickel-metal hydride secondary battery was assembled in the same manner as in Example 1, except that _4.05 Co _0.6 Mn _0.05 Al _0.3 (Mn content was 0.6% by weight).

(Example 3) The composition of the hydrogen storage alloy was LmNi
_A cylindrical nickel-metal hydride secondary battery was assembled in the same manner as in Example 1, except that _3.9 Co _0.6 Mn _0.2 Al _0.3 (Mn content was 2.6% by weight).

(Example 4) A cylindrical nickel-metal hydride secondary battery was assembled in the same manner as in Example 1 except that the negative electrode described below was used.

That is, 1 part by weight of yttrium oxide (Y ₂ O ₃ ) powder was added to 100 parts by weight of a hydrogen storage alloy powder having the same composition as that described in Example 1. Further, a dispersion of polytetrafluoroethylene (specific gravity: 1.
5, solid content of 60% by weight) in terms of solid content of 2.5 parts by weight,
A paste was prepared by adding 0.125 parts by weight of carboxymethyl cellulose (CMC), 1 part by weight of carbon powder, and 50 parts by weight of water. Thereafter, the paste was applied to punched metal, dried, and pressed to form a paste-type hydrogen storage alloy negative electrode.

(Example 5) The composition of the hydrogen storage alloy was LmNi
Example 4 except that _4.05 Co _0.6 Mn _0.05 Al _0.3
In the same manner as in the above, a cylindrical nickel-metal hydride secondary battery was assembled.

(Example 6) A cylindrical nickel-metal hydride secondary battery was assembled in the same manner as in Example 1 except that the negative electrode described below was used.

That is, the composition is LmNi _4.05 Co _0.6 M
1 part by weight of ytterbium oxide (Yb ₂ O ₃ ) powder was added to 100 parts by weight of the hydrogen storage alloy powder of n _0.05 Al _0.3 . Further, 2.5 parts by weight of a polytetrafluoroethylene dispersion (specific gravity 1.5, solid content 60% by weight) in terms of solid content, carboxymethyl cellulose (CM
C) 0.125 parts by weight, 1 part by weight of carbon powder and 5 parts of water
A paste was prepared by adding 0 parts by weight. Thereafter, the paste was applied to punched metal, dried, and pressed to form a paste-type hydrogen storage alloy negative electrode.

(Example 7) A cylindrical nickel-hydrogen secondary battery was assembled in the same manner as in Example 1 except that the negative electrode described below was used.

That is, the composition is LmNi _4.05 Co _0.6 M
1 part by weight of erbium oxide (Er ₂ O ₃ ) powder was added to 100 parts by weight of a hydrogen storage alloy powder of n _0.05 Al _0.3 .
Furthermore, 2.5 parts by weight of a dispersion of polytetrafluoroethylene (specific gravity 1.5, solid content 60% by weight) in terms of solid content, carboxymethyl cellulose (CMC)
A paste was prepared by adding 0.125 parts by weight, 1 part by weight of carbon powder and 50 parts by weight of water. Thereafter, the paste was applied to punched metal, dried, and pressed to form a paste-type hydrogen storage alloy negative electrode.

Comparative Example 1 Example 1 was repeated except that a nonwoven fabric having a basis weight of 50 g / m ² and a thickness of 0.20 mm prepared from a polypropylene long fiber having a fiber diameter of 10 μm by a spunbond method was used as a separator. In the same manner as in the above, a cylindrical nickel-metal hydride secondary battery was assembled.

After the obtained secondary battery was aged, it was initially charged at 90 ° C. and 0.1 C for 15 hours.

(Comparative Example 2) The uncharged nickel-hydrogen secondary battery assembled in the same manner as in Example 1 was aged, and then was initially charged at 0.1 C for 15 hours in a room temperature atmosphere.

Examples 1 to 7 and Comparative Examples 1
With respect to the secondary battery of No. 2, the change in open circuit voltage when the battery was stored in a discharged state in an atmosphere at 70 ° C. was measured, and the change over time in the open circuit voltage is shown in FIG. Also, when the open circuit voltage is 1.0
The time to fall to V was measured, and the results are shown in Table 1 below.

[0064]

[Table 1]

As is clear from Table 1 and FIG.
It can be seen that the secondary battery obtained by the method of Example 7 can suppress a voltage drop when stored in a high-temperature environment as compared with Comparative Examples 1 and 2, and is excellent in high-temperature storage characteristics.

In the above-described embodiment, an example in which the present invention is applied to a cylindrical nickel-metal hydride secondary battery is described. However, the present invention can be similarly applied to a square nickel-metal hydride secondary battery.

[0067]

As described in detail above, the method for manufacturing a nickel-metal hydride secondary battery according to the present invention has remarkable effects such as improvement in high-temperature storage characteristics.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing an example of a nickel-metal hydride secondary battery manufactured by a method according to the present invention.

FIG. 2 is a characteristic diagram showing a change over time of an open circuit voltage during high-temperature storage in the secondary batteries of Examples 1 to 7 and Comparative Examples 1 and 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Container, 2 ... Positive electrode, 4 ... Negative electrode, 5 ... Electrode group, 7 ... Sealing plate.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazuta Takeno 3-4-10 Minamishinagawa, Shinagawa-ku, Tokyo Toshiba Battery Corporation F-term (reference) 5H003 AA03 BA07 BB02 BD01 BD04 5H021 CC02 EE04 EE16 5H028 AA05 BB10 EE01 EE06 HH01 HH08

Claims (4)

[Claims] 1. A nickel-hydrogen secondary battery including a separator interposed between a positive electrode and a negative electrode containing a hydrogen storage alloy and comprising a sheet containing polyolefin-based fibers grafted with a hydrophilic vinyl monomer is assembled. A method for producing a nickel-metal hydride secondary battery, comprising: a step of: initially charging the secondary battery at 40 to 100 ° C. 2. The Mn content of the hydrogen storage alloy is set to 0.1.
The method for producing a nickel-metal hydride secondary battery according to claim 1, wherein the content is 6 to 2.6% by weight. 3. The method for manufacturing a nickel-metal hydride secondary battery according to claim 1, wherein the negative electrode includes at least one selected from a rare earth element simple substance and a rare earth element compound. 4. The method according to claim 4, wherein the rare earth element is at least one element selected from Y, Yb and Er.