JPH11273715A - Nickel hydrogen secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nickel hydrogen secondary battery having a paste type positive electrode, which exhibits high charge efficiency, under high temperature atmosphere. SOLUTION: A nickel hydrogen battery has a paste type positive electrode 2 prepared by applying an active material mainly comprising nickel hydroxide to a conductive substrate, a negative electrode 4, and a separator 3 interposed between the positive electrode 2 and the negative electrode 4. The positive electrode 2 contains 0.05-5 wt.% zirconium hydroxide based on the weight of the nickel hydroxide, and the separator 3 has a hydrophilic group having an ion exchange function.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nickel-metal hydride secondary battery, and more particularly to a nickel-metal hydride secondary battery having an improved paste-type positive electrode.

[0002]

2. Description of the Related Art Conventionally, as a positive electrode of a nickel-metal hydride secondary battery, for example, carbonyl nickel is sintered on a punched metal, and a nickel salt such as nickel nitrate is filled in a conductive substrate in the form of an aqueous solution. A so-called sintering type, which converts into nickel hydroxide in an alkaline solution, has been used. The advantage of the sintering method is that the pore size of the sintered body of carbonyl nickel, which is the substrate, is a very fine structure of several μm to 10 μm. is there. However, since the ratio of the substrate volume to the entire positive electrode needs to be about 20%, the filling amount of nickel hydroxide as an active material is limited accordingly. As a result, the capacity density of the positive electrode was 450 m
There is a problem that only about Ah / cc can be obtained.

[0003] Under such circumstances, a paste-type positive electrode has been proposed. This paste type positive electrode has a pore size of 100 to 5
A paste prepared by adding a desired solvent and a polymer binder to powdered nickel hydroxide as a conductive substrate using a sponge-like or felt-like porous metal body of 00 μm is filled in the holes of the substrate, and dried. , By pressing. Accordingly, the paste-type positive electrode can reduce the volume ratio of the substrate to the whole to 10% or less, and accordingly,
It is possible to increase the amount of powdered nickel hydroxide that is an active material, or it can be converted to a capacity density of 600.
It can be improved by about mAh / cc.

The powdered nickel hydroxide used for the above-mentioned paste type positive electrode is generally prepared by adding an aqueous solution of a nickel salt such as nickel nitrate or nickel sulfate to excess sodium hydroxide or hydroxide in the same manner as in the sintering method. It is obtained by reacting with an aqueous alkali solution such as potassium, and washing and drying the precipitate of particles having a diameter of 1 μm to several tens μm.

[0005] However, the nickel-hydrogen secondary battery provided with the paste-type positive electrode has a problem that the charging efficiency in a high-temperature atmosphere is low and the discharge capacity is reduced. The main cause of this problem is that, under a high-temperature atmosphere, the overvoltage of the oxygen generation reaction at the positive electrode is reduced, whereby the charging reaction of nickel hydroxide and the oxygen generation reaction compete with each other, and the charging efficiency is reduced. .

As a solution to the above problem, it has been proposed to add a metal such as cobalt or cadmium to nickel hydroxide by coprecipitation. The former metal has a function of lowering the oxidation potential of the positive electrode, and the latter metal has a function of increasing the oxygen generation overvoltage of the positive electrode. Therefore, the charging efficiency in a high-temperature atmosphere can be improved. Japanese Patent Application Laid-Open No. 5-28992 discloses Y, In, Sb, Ba, C
It is disclosed that by adding compounds of a and Be, the oxygen generation overpotential of the positive electrode is increased, and the charging efficiency in a high-temperature atmosphere is improved.

On the other hand, JP-A-8-22825 discloses a method of co-precipitating Zr with nickel hydroxide, and JP-A-8-222.
No. 213 discloses a method of adding a Zr compound to a positive electrode using nickel hydroxide as an active material, respectively.

Japanese Patent Application Laid-Open No. 10-21903 discloses that a positive electrode containing nickel hydroxide as an active material is made of ZrO ₂ or ZrO ₂ .
The addition of a zirconium compound such as nH ₂ O (n = 1,2) or Zr (OH) ₄ is disclosed.

[0009]

However, as disclosed in JP-A-8-22825, in a positive electrode containing an active material in which nickel hydroxide is co-precipitated with Zr, the Zr compound existing inside the active material is heated at a high temperature. It does not directly contribute to the improvement of efficiency in charging in an atmosphere. This is because the charging efficiency under a high-temperature atmosphere is greatly affected by the surface state of nickel hydroxide. As a result, the co-precipitation amount of Zr must be increased more than necessary. There has been a problem that the discharge capacity and discharge voltage as a positive electrode decrease.

Further, as disclosed in JP-A-8-222213, Zr compounds include, for example, ZrO ₂ ,
A positive electrode to which ZrO (CH ₂ COO) ₂ , ZrB _2, or the like has been added has a problem that a sufficient improvement in high-temperature charging efficiency cannot be achieved.

Further, as disclosed in JP-A-10-21903, ZrO.nH ₂ O (n = 1,2)
Alternatively, in the method of adding a Zr compound such as Zr (OH) _4, the Zr compound added to the positive electrode gradually dissolves in the electrolytic solution and diffuses into the negative electrode. The amount of is reduced. Therefore, there is a problem that the improvement of the high-temperature charging efficiency cannot be maintained for a long time. An object of the present invention is to provide a nickel-metal hydride secondary battery provided with a paste-type positive electrode showing high charging efficiency under a high-temperature atmosphere.

[0012]

The nickel-hydrogen secondary battery according to the present invention comprises a paste-type positive electrode in which a conductive substrate is coated and filled with an active material mainly composed of nickel hydroxide; a negative electrode; And a separator disposed in the positive electrode, wherein the positive electrode has a zirconium hydroxide in the range of 0.05 to 0.05 with respect to the nickel hydroxide.
The separator contains 5% by weight, and the separator has a hydrophilic group having an ion exchange ability.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A nickel-metal hydride secondary battery (cylindrical nickel-metal hydride secondary battery) according to the present invention will be described below with reference to FIG. An electrode group 5 produced by laminating a paste-type positive electrode 2, a separator 3, and a paste-type negative electrode 4 and winding them in a spiral shape is accommodated in a cylindrical container 1 having a bottom. 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 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
The sealing plate 7 is disposed between the peripheral edge of the sealing plate 7 and the inner surface of the upper opening of the container 1 by caulking to reduce the diameter of the upper opening inward.
It is airtightly fixed through. One end of the positive electrode lead 9 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. Circular holding plate 1 made of insulating material with a hole in the center
Numeral 2 is arranged on the positive electrode terminal 10 so that the projection of the positive electrode terminal 10 protrudes 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 paste-type positive electrode 2, paste-type negative electrode 4, separator 3, and electrolyte will be described. 1) Paste-type positive electrode 2 This paste-type positive electrode 2 includes nickel hydroxide particles as an active material, zirconium hydroxide added to nickel hydroxide by 0.05 to 5% by weight, a conductive material, and a polymer. A binder is kneaded with water to prepare a paste, the paste is applied or filled on a conductive substrate, and dried,
It is produced by molding.

The nickel hydroxide particles may be nickel hydroxide alone or particles obtained by coprecipitating different elements such as Co and Zn. The zirconium hydroxide has Zr on the positive electrode.
It is thought to exist in the form of O (OH) ₂ .
The method for preparing the zirconium hydroxide is not particularly limited, but, for example, an alkaline aqueous solution is added to an aqueous solution in which a Zr salt is dissolved to precipitate Zr hydroxide, and the precipitate is filtered and washed with water. And drying. The Zr salt used here may be any water-soluble one, and examples thereof include zirconium chloride, zirconium nitrate, and zirconium sulfate.

The amount of the Zr hydroxide added to the nickel hydroxide is specified for the following reason. If the addition amount of Zr hydroxide is less than 0.05% by weight, it becomes difficult to improve the high-temperature charging efficiency. On the other hand, if the amount of Zr hydroxide exceeds 5% by weight, the amount of Zr hydroxide becomes too large, and the amount of nickel hydroxide in the positive electrode relatively decreases, resulting in a decrease in utilization and a decrease in capacity. And so on. A more preferred addition amount of Zr hydroxide is
0.1 to 3% by weight.

Examples of the conductive material include cobalt oxide and cobalt hydroxide. Examples of the polymer binder include carboxymethyl cellulose, methyl cellulose, sodium polyacrylate,
Polytetrafluoroethylene and the like can be mentioned.

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

2) Paste type negative electrode 4 This paste type negative electrode 4 is prepared by adding a conductive material to a hydrogen storage alloy powder, kneading the mixture with a polymer binder and water to prepare a paste, and applying this paste to a conductive substrate. It is manufactured by filling, drying and molding.

The hydrogen storage alloy is not particularly limited, as long as it can store hydrogen electrochemically generated in the electrolyte and can easily release the stored hydrogen during discharge. . As this hydrogen storage alloy,
For example LaNi _5, MmNi ₅ (Mm; misch metal), LmNi ₅ (Lm; lanthanum enriched misch metal), or some of these Ni Al, Mn, C
o, Ti, Cu, Zn, Zr, Cr, B, etc.
e-type ones can be mentioned. Among them, the general formula Lm
Ni _x Mn _y A _z (However, A is shown Al, at least one metal selected from Co, the atomic ratio x, y, z is the total value of 4.8 ≦ x + y + z ≦ 5.4) is represented by It is preferable to use one.

Examples of the polymer binder include those similar to those used in the positive electrode 2. 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.

3) Separator 3 The separator 3 is not particularly limited in its material and form as long as it has a hydrophilic group having ion exchange ability on the surface and is an insulator having sufficient hydrophilicity and air permeability. From the viewpoint of improving various characteristics of the hydrogen secondary battery, it is preferable that the battery is formed from a sheet-like material made of polyolefin-based synthetic resin fibers.

As the polyolefin-based synthetic resin fiber, a polyolefin single fiber, a core-sheath composite fiber in which a polyolefin fiber different from the polyolefin fiber is coated on the surface of a core material composed of polyolefin fiber, and polyolefin fibers different from each other are used. A composite fiber having a divided structure joined in a circle can be used. Examples of the polyolefin include polyethylene and polypropylene.

Examples of the sheet-like material containing the polyolefin-based synthetic resin fiber include a nonwoven fabric made of the above-mentioned polyolefin-based synthetic resin fiber, a woven fabric made of the same, or a composite sheet made of these nonwoven fabrics and a woven fabric. be able to. The nonwoven fabric is, for example, a dry method,
It is produced by a wet method, a spun bond method, a melt blow method, or the like. The average fiber diameter of the polyolefin-based synthetic resin fibers is preferably 1 to 20 μm from the viewpoint of mechanical strength and prevention of short circuit between the positive electrode and the negative electrode. If the average fiber diameter of the synthetic resin fibers is less than 1 μm, the mechanical strength of the separator may be reduced, which may make battery assembly difficult. On the other hand, if the average fiber diameter of the synthetic resin fibers exceeds 20 μm, the coverage of the separator may decrease, and short-circuits between positive and negative electrodes may occur frequently. The more preferable average fiber diameter of the synthetic resin fibers is 3 to 15 μm.

The separator 3 is provided with a functional group having an ion exchange function on the fiber surface. For example, the sheet-like material obtained by graft polymerization of a vinyl monomer or the sheet-like material is immersed in sulfuric acid to be sulfonated. Are preferred. Here, as the vinyl monomer having a hydrophilic group, for example, acrylic acid, methacrylic acid, esters of the acrylic acid and the methacrylic acid, vinyl pyridine, styrene sulfonic acid, directly react with an acid or base such as styrene salt And those having a functional group capable of forming a salt upon hydrolysis after graft copolymerization. Acrylic acid is preferred among the vinyl monomers.

The amount of ion exchange of the hydrophilic group is expressed as an amount of ion exchange per weight of the separator.
It is preferably 0 m-eq / g. 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. In particular, a nickel-hydrogen secondary battery provided with an electrolytic solution in which a NaOH aqueous solution or a LiOH aqueous solution is mixed with a KOH aqueous solution is formed by the interaction between Li and Na ions in the electrolytic solution and the above-described Zr hydroxide added to the positive electrode. The high-temperature charge acceptability is improved as compared with the case where the electrolyte solution of each alkali component alone is used. Among them, KOH, LiOH and Na
The highest effect can be exhibited when a mixed solution of OH is used. The concentration of KOH in these electrolytes is 2.0 to
It is desirable to set it to 9.0N, more preferably 3.0 to 8.5N. The concentration of NaOH is desirably in the range of 1.0 to 6.0 N, more preferably 2.0 N to 5.0 N. It is desirable that the concentration of LiOH be in the range of 0.3 to 2.0 N, more preferably 0.5 to 1.5 N.

The nickel-hydrogen secondary battery according to the present invention described above is provided with a paste-type positive electrode in which a conductive substrate is coated and filled with an active material mainly composed of nickel hydroxide, a negative electrode, and a positive electrode and a negative electrode. A positive electrode, the zirconium hydroxide being 0.05 to 5% by weight based on the nickel hydroxide.
And the separator has a configuration having a hydrophilic group capable of ion exchange.

In the secondary battery having such a structure, a predetermined amount of Zr hydroxide is added to the positive electrode, and the ZrO ₂ , ZrO (CH ₂ COO) ₂ , and ZrB ₂ are added to the positive electrode by a coprecipitation method. Since the effect of increasing the overvoltage of the oxygen generation reaction can be achieved with a small amount as compared with the addition, the charging efficiency in a high-temperature atmosphere can be improved while maintaining a sufficient discharge capacity and discharge voltage.

Further, by using a separator having a hydrophilic group having an ion exchange function on the fiber surface, Zr ions eluted from the Zr compound of the positive electrode diffuse to the negative electrode due to the hydrophilic group having an ion exchange function of the separator. Not only can be suppressed and the amount of Zr in the positive electrode can be prevented from decreasing, but also Zr can be made to exist at an extremely high concentration on the positive electrode surface. In order to improve the high-temperature charging efficiency, the state of the positive electrode surface and the active material surface is particularly important. As described above, the Zr is present at a high concentration on the positive electrode surface to further improve the high-temperature charging high rate. And the effect can be maintained for a long period of time.

Further, when an electrolytic solution containing LiOH and NaOH is used, the utilization factor can be improved. However,
Use of an electrolytic solution containing LiOH and NaOH has a disadvantage that the cycle characteristics of an alkaline secondary battery are deteriorated. For this reason, as in the present invention, a predetermined amount of Z
By adding a hydroxide, the LiOH, N
The effect of compensating for the demerit of deterioration in cycle characteristics can be exerted while maintaining the improvement of the utilization rate due to the use of the electrolytic solution containing aOH.

In FIG. 1 described above, the separator 3 is interposed between the positive electrode 2 and the negative electrode 4 and spirally wound and accommodated in the bottomed cylindrical container 1. The battery is not limited to such a structure. For example, a prismatic nickel-metal hydride secondary battery may be configured by interposing a separator between a positive electrode and a negative electrode, and stacking a plurality of the laminated members in a bottomed rectangular cylindrical container.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Example 1 <Preparation of Paste-Type Positive Electrode> First, while maintaining an aqueous solution in which zirconium chloride was dissolved in 100 mL of pure water at 45 ° C., a 4N-KOH aqueous solution containing 10% by volume of aqueous ammonia was gradually added, and an aqueous solution was added. When the pH of the mixture reached 10, the mixture was stirred while maintaining the pH to precipitate Zr hydroxide. The precipitate was filtered, washed with water, and dried to form a Zr hydroxide.

Next, a mixed powder comprising 90 parts by weight of nickel hydroxide particles and 10 parts by weight of cobalt oxide powder was added to:
Zr made by the above method for the nickel hydroxide particles
Hydroxide 1.0 part by weight, carboxymethyl cellulose 0.15 part by weight, sodium polyacrylate 0.15 part by weight, dispersion of polytetrafluoroethylene (specific gravity 1.5, solid content 60% by weight) was converted to solid content. With 0.
The paste was prepared by adding 5 parts by weight, adding 45 parts by weight of pure water thereto and kneading. Subsequently, after this paste was filled in a nickel-plated fiber substrate, the paste was further applied to both surfaces thereof, dried, and rolled by roller pressing to produce a paste-type positive electrode.

<Preparation of Paste Type Negative Electrode> A commercially available lanthanum-enriched misch metal Lm and Ni, Co, Mn,
LmNi _4.0 Co _0.4
A hydrogen storage alloy having a composition of Mn _0.3 Al _0.3 was produced. The hydrogen storage alloy was mechanically pulverized and passed through a 200-mesh sieve. Obtained hydrogen storage alloy powder 10
0.5 parts by weight of sodium polyacrylate and 0.125 of carboxymethyl cellulose (CMC) per 0 parts by weight
By mixing 2.5 parts by weight of a polytetrafluoroethylene dispersion (specific gravity 1.5, solid content 60 wt%) 2.5 parts by weight and carbon powder 1.0 part by weight as a conductive material with water 50 parts by weight, the paste is obtained. Prepared.
This paste was applied to punched metal, dried and then molded under pressure to produce a paste type negative electrode.

<Preparation of Separator> A nonwoven fabric was prepared from a polypropylene resin by a spunbonding method. Subsequently, the nonwoven fabric was immersed in an aqueous solution of acrylic acid, and then irradiated with ultraviolet rays to graft copolymerize the acrylic acid monomer. Subsequently, the nonwoven fabric was washed to remove unreacted acrylic acid, and then dried to produce a separator having a basis weight of 45 g / m ² and a thickness of 0.12 mm. The ion exchange amount of this separator is 0.1.
It was 5 m-eq / g.

Next, the separator was interposed between the negative electrode and the positive electrode and spirally wound to form an electrode group. Such an electrode group and an electrolytic solution comprising 8N KOH were housed in a cylindrical container having a bottom to assemble an AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above.

Example 2 Zr for nickel hydroxide
Example 1 except that the amount of hydroxide added was 0.1% by weight.
A paste-type positive electrode was produced in the same manner as in Example 1, and the obtained positive electrode was spirally wound together with the same negative electrode and separator as in Example 1 to produce an electrode group. Such an electrode group was housed in a bottomed cylindrical container together with an electrolytic solution comprising 8N KOH to assemble the AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above.

Example 3 Zr for nickel hydroxide
Example 1 except that the amount of hydroxide added was 0.5% by weight.
A paste-type positive electrode was produced in the same manner as in Example 1, and the obtained positive electrode was spirally wound together with the same negative electrode and separator as in Example 1 to produce an electrode group. Such an electrode group was housed in a bottomed cylindrical container together with an electrolytic solution comprising 8N KOH to assemble the AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above.

Example 4 Zr for nickel hydroxide
Example 1 except that the amount of hydroxide added was 3.0% by weight.
A paste-type positive electrode was produced in the same manner as in Example 1, and the obtained positive electrode was spirally wound together with the same negative electrode and separator as in Example 1 to produce an electrode group. Such an electrode group was housed in a bottomed cylindrical container together with an electrolytic solution comprising 8N KOH to assemble the AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above.

Example 5 Zr for nickel hydroxide
Example 1 except that the amount of hydroxide added was 5.0% by weight.
A paste-type positive electrode was produced in the same manner as in Example 1, and the obtained positive electrode was spirally wound together with the same negative electrode and separator as in Example 1 to produce an electrode group. Such an electrode group was housed in a bottomed cylindrical container together with an electrolytic solution comprising 8N KOH to assemble the AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above.

Example 21 Z for Nickel Hydroxide
A paste-type positive electrode was prepared in the same manner as in Example 1 except that the amount of the r-hydroxide was changed to 0.05% by weight, and the obtained positive electrode was spirally wound with the same negative electrode and separator as in Example 1. The electrode group was formed by winding. Such an electrode group was housed in a bottomed cylindrical container together with an electrolytic solution comprising 8N KOH to assemble the AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above.

Comparative Example 1 A paste-type positive electrode was prepared in the same manner as in Example 1 except that nickel hydroxide particles were used as the positive electrode active material and Zr hydroxide was not added. An electrode group was prepared by spirally winding the same negative electrode and separator as in Example 1. Such an electrode group was housed in a bottomed cylindrical container together with an electrolytic solution comprising 8N KOH to assemble the AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above.

Comparative Example 2 Zr for Nickel Hydroxide
A paste-type positive electrode was prepared in the same manner as in Example 1 except that the amount of the hydroxide was changed to 0.025% by weight, and the obtained positive electrode was spirally wound with the same negative electrode and separator as in Example 1. This was turned to produce an electrode group. Such an electrode group was housed in a bottomed cylindrical container together with an electrolytic solution comprising 8N KOH to assemble the AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above.

Comparative Example 3 Zr for Nickel Hydroxide
Example 1 except that the amount of hydroxide added was 6.0% by weight.
A paste-type positive electrode was produced in the same manner as in Example 1, and the obtained positive electrode was spirally wound together with the same negative electrode and separator as in Example 1 to produce an electrode group. Such an electrode group was housed in a bottomed cylindrical container together with an electrolytic solution comprising 8N KOH to assemble the AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above.

[0046] (Comparative Example 4) using a ZrO ₂ powder as an additive, except that the ZrO ₂ powder the ZrO ₂ powder with respect to the nickel hydroxide particles was added 1.0% by weight Zr terms,
A paste-type positive electrode was prepared in the same manner as in Example 1,
The obtained positive electrode was spirally wound together with the same negative electrode and separator as in Example 1 to produce an electrode group. Such an electrode group was housed in a bottomed cylindrical container together with an electrolytic solution comprising 8N KOH to assemble the AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above.

Comparative Example 5 Zr (CH ₃ C) was used as an additive.
OO) ₂ powder, and the paste method was performed in the same manner as in Example 1 except that this Zr (CH ₃ COO) ₂ powder was added to the nickel hydroxide particles in an amount of 1.0% by weight of ZrO ₂ powder in terms of Zr. A positive electrode was prepared, and the obtained positive electrode was used in Example 1.
The electrode group was produced by spirally winding the same negative electrode and separator as in the above. Such an electrode group was housed in a bottomed cylindrical container together with an electrolytic solution comprising 8N KOH to assemble the AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above.

(Comparative Example 6) Zirconium nitrate was added to an aqueous solution of nickel salt, and aqueous ammonia of 10% by volume was further added. Then, an aqueous solution of KOH was gradually dropped, and the pH was maintained at 11, whereby Zr was coprecipitated. Spherical nickel hydroxide particles were produced. At this time, the coprecipitation amount of Zr was 1.0% by weight based on the spherical nickel hydroxide particles. This Zr
A paste-type positive electrode was prepared in the same manner as in Example 1 using the nickel hydroxide particles in which was coprecipitated, and the obtained positive electrode was spirally wound together with the same negative electrode and separator as in Example 1 to form an electrode group. Was prepared. Such an electrode group is 8N
AA size cylindrical nickel-metal hydride secondary battery having the above-described structure shown in FIG. 1 was housed in a cylindrical container having a bottom together with the electrolytic solution comprising KOH.

The secondary batteries of Examples 1 to 5 and 21 and Comparative Examples 1 to 6 were charged at 0.1 CmA and then charged at 1 Cm.
A discharged to 1.0V. With respect to the secondary batteries of Examples 1 to 5 and 21 and Comparative Examples 1 to 6 which were charged and discharged as described above, the utilization rate when charged in a high-temperature atmosphere was measured. The result is shown in FIG. The measurement of the utilization rate when charged in a high-temperature atmosphere was performed after the battery was charged at 0.1 CmA in an atmosphere of 60 ° C. at 150% and then left at 20 ° C. to reach the same temperature as the room temperature. 1.0Cm
The discharge capacity at the time of discharging to 1.0 V at A was divided by the theoretical capacity of nickel hydroxide filled in the positive electrode.

As is apparent from the results of FIG. 2, the positive electrodes of Examples 1 to 5 in which Zr hydroxide was added in an amount of 0.05 to 5% by weight with respect to nickel hydroxide were the same as the positive electrodes of Comparative Examples 1 to 6. It can be seen that the usage rate during high-temperature charging can be improved. In particular, the results of Examples 1 to 5 show that the addition of a small amount of the Zr hydroxide can more effectively increase the oxygen generation overvoltage during high-temperature charging and improve the utilization during high-temperature charging.

(Example 6) In the same manner as in Example 1, a positive electrode in which Zr hydroxide was added in an amount of 1.0% by weight with respect to nickel hydroxide was spirally wound together with a negative electrode and a separator to form an electrode group. . Such an electrode group is housed in a bottomed cylindrical container together with an electrolytic solution consisting of 7.5N KOH and 0.5N NaOH and has the above-described structure shown in FIG.
A cylindrical nickel-metal hydride secondary battery having a size was assembled.

Example 7 As in Example 1, a positive electrode in which Zr hydroxide was added in an amount of 1.0% by weight with respect to nickel hydroxide was spirally wound together with a negative electrode and a separator to form an electrode group. . Such an electrode group was accommodated in a bottomed cylindrical container together with an electrolytic solution comprising 7N KOH and 1N NaOH to assemble the AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above.

Example 8 An electrode group was prepared by spirally winding a positive electrode containing 1.0% by weight of Zr hydroxide relative to nickel hydroxide together with a negative electrode and a separator in the same manner as in Example 1. . Such an electrode group was housed in a bottomed cylindrical container together with an electrolytic solution composed of 6N KOH and 2N NaOH to assemble the AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above.

Example 9 An electrode group was prepared by spirally winding a positive electrode containing 1.0% by weight of Zr hydroxide relative to nickel hydroxide together with a negative electrode and a separator in the same manner as in Example 1. . Such an electrode group was housed in a bottomed cylindrical container together with an electrolytic solution composed of 4N KOH and 4N NaOH to assemble the AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above.

Example 10 In the same manner as in Example 1, a positive electrode in which Zr hydroxide was added in an amount of 1.0% by weight with respect to nickel hydroxide was spirally wound together with a negative electrode and a separator to form an electrode group. . Such an electrode group was housed in a bottomed cylindrical container together with an electrolytic solution comprising 3N KOH and 5N NaOH to assemble the AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above.

Example 11 An electrode group was prepared by spirally winding a positive electrode containing 1.0% by weight of Zr hydroxide with respect to nickel hydroxide together with a negative electrode and a separator in the same manner as in Example 1. . Such an electrode group was accommodated in a bottomed cylindrical container together with an electrolytic solution composed of 2N KOH and 6N NaOH to assemble the AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above.

Example 12 Similarly to Example 1, a positive electrode in which Zr hydroxide was added in an amount of 1.0% by weight to nickel hydroxide was spirally wound together with a negative electrode and a separator to form an electrode group. . Such an electrode group was housed in a bottomed cylindrical container together with an electrolytic solution comprising 1N KOH and 7N NaOH to assemble the AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above.

Comparative Example 7 A paste-type positive electrode was prepared in the same manner as in Example 1 except that nickel hydroxide particles were used as the positive electrode active material and Zr hydroxide was not added. An electrode group was prepared by spirally winding the same negative electrode and separator as in Example 1. Such an electrode group was housed in a bottomed cylindrical container together with an electrolytic solution composed of 4N KOH and 4N NaOH to assemble the AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above.

The secondary batteries of Examples 6 to 12 and Comparative Example 7 were charged at 0.1 CmA and then charged at 1 CmA.
Discharged to 0V. Example 6 in which such charge / discharge was performed
With respect to the secondary batteries of Nos. To 12 and Comparative Example 7, the utilization factor when charged in a high-temperature atmosphere was measured in the same manner as in Example 1. The result is shown in FIG. FIG. 3 also shows the results of Example 1 and Comparative Example 1 described above.

As is apparent from FIG. 3, Examples 6 to 12 were provided with a paste-type positive electrode in which 0.05 to 5% by weight of Zr hydroxide was added to nickel hydroxide and an electrolytic solution in which KOH was mixed with NaOH. Of the secondary battery of Comparative Example 7 can improve the utilization factor during high-temperature charging. Further, the secondary batteries of Examples 6 to 12 have a paste-type positive electrode having a similar configuration, and the utilization factor at the time of high-temperature charging is improved as compared with Example 1 including an electrolyte solution consisting of only KOH. You can see that.
This is considered to be due to a synergistic effect of Zr hydroxide added to the positive electrode and NaOH mixed in the electrolyte.

Example 13 As in Example 1, a positive electrode in which 1.0 wt% of Zr hydroxide was added to nickel hydroxide was spirally wound together with a negative electrode and a separator to form an electrode group. . Such an electrode group is made of 7.85N KO.
An AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above was housed in a cylindrical container having a bottom together with an electrolytic solution comprising H and 0.15N LiOH.

Example 14 Similarly to Example 1, a positive electrode in which 1.0 wt% of Zr hydroxide was added to nickel hydroxide was spirally wound together with a negative electrode and a separator to prepare an electrode group. . Such an electrode group is made of 7.7N KOH
A having the above-described structure shown in FIG.
An A-size cylindrical nickel-metal hydride secondary battery was assembled.

Example 15 As in Example 1, an electrode group was prepared by spirally winding a positive electrode containing 1.0% by weight of Zr hydroxide with respect to nickel hydroxide together with a negative electrode and a separator. . Such an electrode group is made of 7.5N KOH
A having the above-described structure shown in FIG.
An A-size cylindrical nickel-metal hydride secondary battery was assembled.

Example 16 As in Example 1, an electrode group was prepared by spirally winding a positive electrode containing 1.0% by weight of Zr hydroxide with respect to nickel hydroxide together with a negative electrode and a separator. . Such an electrode group was housed in a bottomed cylindrical container together with an electrolytic solution composed of 7N KOH and 1N LiOH to assemble the AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above.

(Example 17) As in Example 1, a positive electrode in which Zr hydroxide was added in an amount of 1.0% by weight with respect to nickel hydroxide was spirally wound together with a negative electrode and a separator to prepare an electrode group. . Such an electrode group is made of 6.5N KOH
A having the above-described structure shown in FIG.
An A-size cylindrical nickel-metal hydride secondary battery was assembled.

Example 18 Similarly to Example 1, a positive electrode in which Zr hydroxide was added in an amount of 1.0% by weight to nickel hydroxide was spirally wound together with a negative electrode and a separator to form an electrode group. . Such an electrode group was housed in a bottomed cylindrical container together with an electrolytic solution composed of 6N KOH and 2N LiOH to assemble the AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above.

Example 19 As in Example 1, a positive electrode in which Zr hydroxide was added in an amount of 1.0% by weight with respect to nickel hydroxide was spirally wound together with a negative electrode and a separator to form an electrode group. . Such an electrode group is formed of 5.5N KOH
A having the above-described structure shown in FIG.
An A-size cylindrical nickel-metal hydride secondary battery was assembled.

Example 20 As in Example 1, an electrode group was prepared by spirally winding a positive electrode containing 1.0% by weight of Zr hydroxide with respect to nickel hydroxide together with a negative electrode and a separator. . Such an electrode group is made of 3N KOH,
An AA-sized cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above was housed in a bottomed cylindrical container together with an electrolytic solution consisting of N NaOH and 1N LiOH.

Comparative Example 8 A paste-type positive electrode was prepared in the same manner as in Example 1 except that nickel hydroxide particles were used as the positive electrode active material and Zr hydroxide was not added. An electrode group was prepared by spirally winding the same negative electrode and separator as in Example 1. Such an electrode group was housed in a bottomed cylindrical container together with an electrolytic solution composed of 7N KOH and 1N LiOH to assemble the AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above.

The secondary batteries of Examples 13 to 20 and Comparative Example 8 were charged at 0.1 CmA, and then discharged to 1.0 V at 1 CmA. With respect to the secondary batteries of Examples 13 to 20 and Comparative Example 8 which were charged and discharged in such a manner, the utilization rates when charged in a high-temperature atmosphere by the same method as in Example 1 were measured. The utilization rate of the secondary battery of Example 20 using the electrolyte composed of three components of KOH, NaOH, and LiOH was 75%, and Examples 13 to
The results of 19 and Comparative Example 8 are shown in FIG. FIG. 4 also shows the results of Example 1 and Comparative Example 1 described above.

As is apparent from FIG. 4, Examples 13 to 19 provided with a paste-type positive electrode in which 0.05 to 5% by weight of Zr hydroxide was added to nickel hydroxide and an electrolytic solution in which KOH was mixed with LiOH. Of the secondary battery of Comparative Example 8 can improve the utilization factor during high-temperature charging. Further, the secondary batteries of Examples 13 to 19 each have a paste-type positive electrode having a similar configuration, and have the same configuration as that of Example 1 including an electrolytic solution consisting of only KOH.
It can be seen that the utilization rate at the time of high-temperature charging is improved as compared with. This is considered to be due to a synergistic effect between Zr hydroxide added to the positive electrode and LiOH mixed in the electrolyte. In particular, the utilization rate of the secondary battery of Example 20 using the electrolyte composed of three components of KOH, NaOH, and LiOH was 75%.
%, The highest value, and has a remarkable effect.

Comparative Example 9 A paste-type positive electrode was prepared in the same manner as in Example 1 except that nickel hydroxide particles were used as the positive electrode active material and Zr hydroxide was not added. An electrode group was prepared by spirally winding the same negative electrode and separator as in Example 1. Such an electrode group was formed using the same composition as in Example 20, that is, 3N KOH,
An AA-sized cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above was housed in a bottomed cylindrical container together with an electrolytic solution consisting of N NaOH and 1N LiOH.

The secondary batteries of Example 20 and Comparative Example 9 were charged at 1 CmA to 150%, and then charged at 1 Cm.
A repeats charging and discharging until the battery voltage reaches 1.0 V, and the battery voltage is 1.0 V at 1 CmA in each cycle.
The discharge capacity was calculated from the time to reach. The result is shown in FIG.
Shown in The discharge capacity ratio on the vertical axis in FIG. 5 indicates a relative value when the discharge capacity in the first cycle of Example 20 and Comparative Example 9 is 100. The cycle number ratio on the horizontal axis in FIG. 5 indicates the cycle number of the secondary battery of Example 20 as 100, where 100 is the cycle number at which the discharge capacity of the secondary battery of Comparative Example 9 reached 80% of the discharge capacity in the first cycle. It is shown as a relative value.

As is clear from FIG. 5, the secondary battery of Example 20 including the positive electrode to which Zr hydroxide was added was more charged than Comparative Example 9 including the positive electrode to which Zr hydroxide was not added. It has the effect of extending the discharge cycle life. Usually LiOH,
When an electrolytic solution containing NaOH is used, ions of Li and Na are taken into the positive electrode during charging and discharging, and the high-temperature charging efficiency is improved, but the charging and discharging cycle life is reduced. By adding Zr hydroxide to the positive electrode as in Example 20 of the present invention, not only the high-temperature charging efficiency can be improved, but also the charge / discharge cycle life can be improved at the same time.

(Examples 22 to 28) As in Example 1, Z
A positive electrode to which r hydroxide was added in an amount of 1.0% by weight based on nickel hydroxide was spirally wound together with the negative electrode and the separator to prepare seven types of electrode groups. However, the ion exchange amounts of the separators were 0.025 m-eq / g (Example 22), 0.05 m-eq / g (Example 23), respectively.
0.1 m-eq / g (Example 24), 1.0 m-eq / g
g (Example 25), 1.5 m-eq / g (Example 2)
6), 2.0 m-eq / g (Example 27) and 2.5
m-eq / g (Example 28) was used. Each of such electrode groups is made up of 3N KOH, 4N NaOH and 1N
Of the AA-size cylindrical nickel-hydrogen secondary batteries having the structure shown in FIG.

(Example 29) As in Example 1, a cathode in which Zr hydroxide was added in an amount of 1.0% by weight with respect to nickel hydroxide was spirally wound together with the anode and the separator to give 5%.
Seed electrode groups were prepared. However, as the separator, a non-woven fabric made of a polypropylene resin fiber was subjected to sulfonation treatment by immersing it in an aqueous sulfuric acid solution, and the ion exchange amount was 0.05 m-eq / g. Such an electrode group is made up of 3N KOH, 4N NaOH and 1N L
Five types of AA-size cylindrical nickel-metal hydride secondary batteries having the above-described structure shown in FIG. 1 were housed in a bottomed cylindrical container together with the electrolyte solution composed of iOH.

With respect to the secondary batteries of Examples 22 to 29, the utilization rate when charged in a high-temperature atmosphere was measured in the same manner as in Example 1. FIG. 6 shows the result. FIG. 6 also shows the results of Example 20 described above.

As is apparent from FIG. 6, a secondary battery using a separator having a hydrophilic group having an ion exchange ability has a high utilization factor at the time of high-temperature charging, and particularly has an ion exchange amount of 0.05 to
Example 20 using a 2.0 m-eq / g separator,
It can be seen that 23 to 27 and 29 can greatly improve the utilization rate during high-temperature charging.

[0079]

As described above, according to the present invention, it is possible to provide a nickel-metal hydride secondary battery having a paste-type positive electrode exhibiting high charging efficiency under a high-temperature atmosphere.

[Brief description of the drawings]

FIG. 1 is a perspective view of a nickel-metal hydride secondary battery as an example of a nickel-metal hydride secondary battery according to the present invention.

FIG. 2 is a diagram showing utilization rates of nickel-metal hydride secondary batteries of Examples 1 to 5 and Comparative Examples 1 to 6 of the present invention.

FIG. 3 is a diagram showing utilization rates in nickel-metal hydride secondary batteries of Examples 6 to 12 and Comparative Example 7 of the present invention.

FIG. 4 is a diagram showing utilization rates of the nickel-hydrogen secondary batteries of Examples 13 to 19 and Comparative Example 8 of the present invention.

FIG. 5 is a diagram showing charge / discharge cycle characteristics of the nickel-metal hydride secondary batteries of Example 20 and Comparative Example 9 of the present invention.

FIG. 6 is a diagram showing utilization rates in the nickel-metal hydride secondary batteries of Examples 20 and 22 to 29 of the present invention.

[Explanation of symbols]

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

Claims (1)

[Claims] 1. A paste-type positive electrode in which a conductive substrate is coated and filled with an active material mainly composed of nickel hydroxide;
In a nickel-metal hydride secondary battery provided with a separator disposed between the positive and negative electrodes, the positive electrode contains 0.05 to 5% by weight of zirconium hydroxide with respect to the nickel hydroxide, and the separator is A nickel-hydrogen secondary battery having a hydrophilic group having ion exchange ability.