JPH10255786A - Nickel hydrogen secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance charging efficiency under high temperature atmosphere while suppressing formation of γ type oxy-nickel hydroxide by making oxide and/or hydroxide of at least one kind among a zinc atom and 4b group elements contained. SOLUTION: A nickel hydrogen secondary battery is equipped with a positive electrode 2 with a structure in which paste containing an active material particle with nickel hydroxide as a main ingredient is filled in a collector. The active material particle contains oxide and/or hydroxide of at least one kind among a zinc atom and 4b group elements (Si, Ge, Sn, Pb). Since electric potential difference between a balanced voltage and oxygen excess voltage can be made large in the secondary battery equipped with the positive electrode 2 when it is charged under high temperature atmosphere, timing to generate oxygen gas can be delayed, so that charging efficiency can be enhanced. In addition, the secondary battery can reduce a formation quantity of γ oxy-nickel hydroxide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a nickel-hydrogen secondary battery having an improved positive electrode.

[0002]

2. Description of the Related Art Conventionally, as a positive electrode for an alkaline secondary battery, a sintered positive electrode having a very fine pore structure having a pore size of several to 10 μm and having excellent current collecting ability and life characteristics has been frequently used. I was However, since the upper limit of the porosity of the substrate used for the sintered positive electrode is about 80%, the filling amount of the active material is limited, and even if the capacity density is high, it is at most 450.
It was about mAh / cc, and it was not possible to sufficiently respond to a demand for a capacitor having a higher capacity density.

[0003] Under such circumstances, a paste-type nickel positive electrode has been proposed. This positive electrode is formed, for example, by dispersing nickel hydroxide powder, which is an active material, in a solvent together with a binder (for example, carboxymethylcellulose, sodium polyacrylate), and forming the paste into a paste. It is prepared by filling into a sponge-like or felt-like metal porous body having a high porosity, drying and pressing. In such a positive electrode, the filling amount of the active material is increased due to the high porosity of the substrate, and the filling amount is increased to about 600 mAh / cc in terms of capacity density, which is 30 to 50% higher than that of the sintered positive electrode. . Incidentally, the nickel hydroxide powder is generally nickel nitrate,
It is prepared by reacting and crystallizing an aqueous solution of a nickel salt such as nickel sulfate with an excess aqueous solution of sodium hydroxide or potassium hydroxide, and then washing and drying the resulting precipitate.

However, a nickel-hydrogen secondary battery assembled by preparing a group of electrodes by interposing a separator between the above-mentioned paste-type positive electrode and the hydrogen-absorbing alloy negative electrode and storing it in a container together with an alkaline electrolyte is known. In addition, as compared with the case where a sintered positive electrode is used as the positive electrode, there is a problem that the utilization rate of the positive electrode active material is low and the charge and discharge cycle life is short.
The cycle life of the secondary battery is inferior during overcharge.
This is because γ-type nickel oxyhydroxide having a low density and easily absorbing the electrolyte is generated on the positive electrode, the positive electrode expands, the separator is compressed, and the electrolyte is unevenly distributed on the positive electrode. In addition, the secondary battery is operated in a high temperature environment (40
(° C. or higher), the oxygen overvoltage is reduced, and the potential difference between this voltage and the positive electrode equilibrium voltage is reduced. As a result, oxygen gas is generated during charging, and the charging of nickel hydroxide becomes insufficient, and the charging efficiency is reduced. Therefore, the utilization factor and cycle life when used in such an environment are extremely low.

[0005] As means for suppressing the production of the γ-type nickel oxyhydroxide described above, zinc oxide,
It has been proposed to add a hydroxide or use a powder in which nickel hydroxide and zinc hydroxide are coprecipitated. However, there is a problem in that the addition of a zinc compound promotes a decrease in charging efficiency under a high-temperature atmosphere.

As a means for improving the charge and discharge characteristics of the secondary battery, it has been proposed to use nickel hydroxide particles in which cobalt and cadmium are coprecipitated as an active material. When such a method is adopted, the potential difference between the equilibrium potential of the positive electrode during charging and the oxygen overvoltage increases, so that the oxygen gas generation reaction is suppressed and the charging efficiency is improved. However, in order to improve the charging efficiency under a high temperature environment by this method, it is necessary to add a considerable amount of cobalt or cadmium which does not participate in the charge / discharge reaction, and as a result, the amount of nickel hydroxide in the positive electrode decreases, and the battery capacity decreases. There is a problem that it decreases.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a nickel-hydrogen secondary battery having improved charging efficiency in a high-temperature atmosphere while suppressing the generation of γ-type nickel oxyhydroxide by improving the positive electrode. It is intended to provide a battery.

[0008]

A nickel-hydrogen secondary battery according to the present invention comprises: a positive electrode having a structure in which a current collector is filled with a paste containing active material particles containing nickel hydroxide as a main component; A negative electrode containing an alloy and an alkaline electrolyte are provided, and the active material particles contain a zinc atom and at least one oxide and / or hydroxide of a Group 4b element (Si, Ge, Sn, Pb). It is characterized by containing.

The nickel-hydrogen secondary battery according to the present invention comprises:
A positive electrode having a structure in which a paste containing active material particles containing nickel hydroxide as a main component is filled in a current collector, a negative electrode containing a hydrogen storage alloy, and an alkaline electrolyte are provided. Containing 1 to 10% by weight of atoms and 4b
At least one of group elements (Si, Ge, Sn, Pb)
0.1 to 10% by weight of a kind of oxide and / or hydroxide, and a layer containing this oxide and / or hydroxide is present on the surface of the active material particles. .

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of 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 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 circular first 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. Positive electrode lead 9
Has one end connected to the positive electrode 2 and the other end connected to the lower surface of the sealing plate 7. The positive electrode terminal 10 having a hat shape is
It is mounted 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 provided on the positive terminal 10 on the positive terminal 10.
Are arranged so as to protrude from the holes of the holding plate 12. The outer tube 13 is provided with the holding plate 1.
2, the side of the container 1 and the bottom of the container 1.

Next, the paste type positive electrode 2, negative electrode 4, separator 3, and electrolyte will be described. 1) Paste-type positive electrode 2 The positive electrode has a structure in which a paste containing active material particles containing nickel hydroxide (Ni (OH) ₂ ) as a main component is filled in a current collector. The active material particles include a zinc atom (Zn).
And (A) a 4b group element (Si, Ge, S
n, Pb), or (B) at least one hydroxide of the group 4b element, or (C) a compound of both the oxide and the hydroxide. .

The active material particles include (a) a layer containing zinc atoms and having a layer partially or wholly containing an oxide of at least one of the aforementioned Group 4b elements. , (B) containing a zinc atom and partially or entirely at least one of the group 4b elements
Active material particles in which a layer containing a kind of hydroxide is present, (c) active material particles containing a zinc atom and having a layer containing the oxide and the hydroxide on a part or the whole of the surface Is included.

[0013] Of the Group 4b elements, Sn and Si are preferable. The content of zinc atoms in the active material particles is 1 to 1
It is preferable that the content be in the range of 0% by weight. This is due to the following reasons. If the content is less than 1% by weight, it may be difficult to reduce the production amount of γ-type nickel oxyhydroxide. On the other hand, when the content exceeds 10% by weight, a decrease in the positive electrode capacity due to a decrease in the nickel hydroxide content of the positive electrode may become apparent.
A more preferred content is in the range of 3-6% by weight.

The content of the oxide and / or hydroxide of the Group 4b element in the active material particles is preferably in the range of 0.1 to 10% by weight. If the content is out of the range, it may be difficult to increase the charging efficiency under a high temperature environment. On the other hand, when the content exceeds 10% by weight, a decrease in the capacity of the positive electrode due to a decrease in the nickel hydroxide content of the positive electrode may become apparent. In particular, from the viewpoint of improving the high-temperature charging efficiency while minimizing the capacity reduction due to the addition of these compounds, the content is 1 to 6% by weight.
Should be within the range.

The average particle size of the active material particles is 5 to 20 μm.
m. The active material particles can be produced, for example, by the methods described in the following (1) and (2).

(1) Nickel and zinc are dissolved in a sulfuric acid aqueous solution to prepare a sulfate aqueous solution. Aqueous ammonia and an aqueous solution of potassium hydroxide are added dropwise to the obtained aqueous solution of the sulfate while stirring so that the pH of the aqueous solution of the sulfate is in a desired range, and nickel hydroxide particles on which zinc is coprecipitated are deposited and grown. The obtained particles are washed with water, dried, and then dispersed in water. Prepare an aqueous solution of tin sulfate to which a small amount of sulfuric acid is added in order to prevent hydrolysis to tin hydroxide, and stir while dropping the aqueous solution of tin sulfate little by little into the water in which the nickel hydroxide particles are dispersed. . Hydrogen peroxide solution was added to the solution little by little, and the mixture was sufficiently stirred, and the resulting precipitate was filtered, washed with water, and dried to obtain a second or partial surface of the nickel hydroxide particles. A tin oxide (SnO ₂ ) layer is formed to produce the active material particles.

(2) Dissolve silicon dioxide (SiO ₂ ) powder in an aqueous solution of potassium hydroxide heated to 80 to 100 ° C., and allow to stand. To this silicon dioxide solution, nickel hydroxide particles obtained by co-precipitating zinc obtained by the method described in the above (1) are added little by little. Next, the temperature of the solution is gradually lowered to room temperature to form a silicon dioxide (SiO ₂ ) layer on a part or the entire surface of the nickel hydroxide particles, thereby producing the active material particles.

The paste-type positive electrode 2 has, for example, a layer containing an oxide of a Group 4b element on at least a part of its surface, and is electrically conductive to active material particles containing nickel hydroxide as a main component and containing a zinc atom. The paste can be prepared by adding a material, kneading the mixture with a binder and water to prepare a paste, filling the paste into a current collector, drying, and rolling.

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

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

In the nickel-metal hydride secondary battery provided with the positive electrode manufactured by such a method, part or all of the oxides of the group 4b element present on the surface of the active material particles are partially or completely charged or discharged. , 4 due to the effect of alkaline electrolyte
It may be changed to a hydroxide of a group b element.

2) Negative electrode 4 The negative electrode 4 is prepared, for example, 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 filling the paste into a conductive substrate. It is manufactured by drying and molding.

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. . 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. Since the negative electrode containing such a hydrogen storage alloy can suppress the pulverization accompanying the progress of the charge / discharge cycle, the charge / discharge cycle life of the secondary battery can be improved.

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 made of, for example, a polymer non-woven fabric such as a polypropylene non-woven fabric, a nylon non-woven fabric, or a non-woven fabric obtained by mixing polypropylene fibers and nylon fibers. In particular, a polypropylene nonwoven fabric whose surface has been hydrophilized is suitable as a separator.

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 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 housing a laminate in which a plurality of positive and negative electrodes are laminated with a separator interposed therebetween in a bottomed rectangular cylindrical container.

As described in detail above, the nickel-metal hydride secondary battery according to the present invention includes a positive electrode having a structure in which a current collector is filled with a paste containing active material particles containing nickel hydroxide as a main component. The active material particles include a zinc atom and 4b
At least one of group elements (Si, Ge, Sn, Pb)
Contains species of oxides and / or hydroxides. A secondary battery equipped with such a positive electrode can increase the potential difference between the equilibrium voltage of the positive electrode and the oxygen overvoltage during charging in a high-temperature atmosphere, so that the timing of oxygen gas generation can be delayed, Efficiency can be improved. Further, the secondary battery can reduce the amount of γ-nickel oxyhydroxide generated. Therefore, the secondary battery can achieve high capacity and long life not only when used at around normal temperature but also in a high-temperature atmosphere.

The nickel-hydrogen secondary battery according to the present invention includes a positive electrode having a structure in which a current collector is filled with a paste containing active material particles containing nickel hydroxide as a main component. The active material particles contain zinc atoms in an amount of 1 to 10% by weight and at least one oxide and / or hydroxide of a Group 4b element (Si, Ge, Sn, Pb) in an amount of 0.1 to 10%.
Contains 10% by weight. The active material particles have a layer containing the oxide and / or the hydroxide on the surface. A secondary battery provided with such a positive electrode can greatly increase the potential difference between the equilibrium voltage of the positive electrode and the oxygen overvoltage during charging in a high-temperature environment. This is presumably due to the fact that the electrical conductivity of the surface of the active material particles was changed by the above-described oxide layer or hydroxide layer. Therefore, the secondary battery can dramatically improve the charging efficiency of the positive electrode at a high temperature, so that the discharge capacity and cycle life when used in a high-temperature atmosphere can be significantly improved.

[0031]

Embodiments of the present invention will be described below in detail with reference to the drawings. (Example 1) <Preparation of paste-type positive electrode> (Preparation of active material particles) Nickel and zinc were dissolved in a 50 ° C aqueous sulfuric acid solution (the weight ratio of nickel and zinc was 100: 5), and the aqueous sulfate solution was dissolved. Then, ammonia water and an aqueous solution of potassium hydroxide were added dropwise so that the pH of the aqueous solution of the sulfate became 12, and the mixture was stirred to precipitate nickel hydroxide particles on which zinc was coprecipitated and grown. Next, the obtained nickel hydroxide particles were washed with water and dried. When the concentration is 0.071 wt. % Tin sulfate aqueous solution 10
0 ml, the concentration is 96 wt. 0.1% aqueous sulfuric acid solution
1 was added. 50 g of the nickel hydroxide particles is added to 600
The mixture was dispersed in ml of water, and stirred while the tin sulfate aqueous solution was added dropwise little by little. A concentration of 20 wt.
The resulting precipitate was filtered, washed with water, and dried by adding 10 ml of a 10% aqueous hydrogen peroxide solution little by little, and tin oxide (SnO ₂ ) was partially applied to the surface.
Nickel hydroxide particles (active material particles) on which a layer was formed and zinc was coprecipitated were produced. The content of zinc atoms in the particles was 5% by weight. The tin oxide content of the particles was 0.1% by weight. The average particle size of the particles was 10 μm.

(Preparation of Positive Electrode) The active material particles, cobalt monoxide, carboxymethyl cellulose and water were mixed with 10
The mixture was kneaded at a weight ratio of 0: 5: 0.3: 30 to prepare a paste. The paste was filled in a sponge-like nickel porous body, dried, rolled, and then a lead was welded to produce a paste-type nickel positive electrode. <Preparation of Paste-Type Negative Electrode> LmNi _4.0 Co _0.4 Mn _0.3 Al using a commercially available lanthanum-enriched misch metal Lm and Ni, Co, Mn, and Al by a high frequency furnace.
_A hydrogen storage alloy having a composition of _0.3 was prepared. The hydrogen storage alloy was mechanically pulverized and passed through a 200-mesh sieve. 0.5 part by weight of sodium polyacrylate, 0.125 part by weight of carboxymethylcellulose (CMC), and a dispersion of polytetrafluoroethylene (specific gravity: 1.50 parts by weight) based on 100 parts by weight of the obtained hydrogen storage alloy powder.
5, a solid content of 60 wt%) and a paste were prepared by mixing 2.5 parts by weight of carbon powder as a conductive material and 1.0 part by weight of carbon powder together with 50 parts by weight of water. This paste was applied to punched metal, dried and then molded under pressure to produce a paste type negative electrode. <Assembly of Battery> An electrode group was prepared by spirally winding a nonwoven fabric mainly composed of polypropylene fiber as a separator between the positive electrode and the negative electrode. The obtained electrode group is housed in a bottomed cylindrical container, and 8
An alkaline electrolyte comprising an aqueous KOH solution of N is accommodated and sealed, and has the above-described structure shown in FIG.
At 2 Ah, an AA size nickel-metal hydride secondary battery was assembled. (Example 2) A nickel-metal hydride secondary battery having the same structure as that of Example 1 except that the active material particles described below were used for the positive electrode was assembled.

As in Example 1, 50 g of nickel hydroxide particles in which zinc was coprecipitated were dispersed in 600 ml of water. When the concentration is 0.71 wt. 100ml of tin sulfate aqueous solution
At a concentration of 96 wt. 0.1 ml of a 10% aqueous sulfuric acid solution was added. The aqueous solution of tin sulfate was added dropwise to the water in which the nickel hydroxide particles were dispersed, and the mixture was stirred. A concentration of 20 wt. The resulting precipitate was filtered, washed with water and dried by adding 100 ml of a 100% aqueous hydrogen peroxide solution little by little, and a tin oxide (SnO ₂ ) layer was formed on a part of the surface. Thus, nickel hydroxide particles (active material particles) on which zinc was coprecipitated were produced. The tin oxide content of the particles was 1% by weight. (Example 3) A nickel-metal hydride secondary battery having the same configuration as in Example 1 except that the active material particles described below were used for the positive electrode was assembled.

50 g of nickel hydroxide particles in which zinc was coprecipitated as in Example 1 were dispersed in 600 ml of water. When the concentration is 2.1 wt. 100ml of tin sulfate aqueous solution
At a concentration of 96 wt. 0.3 ml of a 10% aqueous sulfuric acid solution was added. The aqueous solution of tin sulfate was added dropwise to the water in which the nickel hydroxide particles were dispersed, and the mixture was stirred. A concentration of 20 wt. The resulting precipitate was filtered, washed with water and dried by adding 100 ml of a 100% aqueous hydrogen peroxide solution little by little, and a tin oxide (SnO ₂ ) layer was formed on a part of the surface. Thus, nickel hydroxide particles (active material particles) on which zinc was coprecipitated were produced. The tin oxide content of the particles was 3% by weight. (Example 4) A nickel-metal hydride secondary battery having the same configuration as that of Example 1 except that the active material particles described below were used for the positive electrode was assembled.

The same nickel coprecipitated nickel hydroxide particles as in Example 1 (50 g) were dispersed in 600 ml of water. When the concentration is 4.2 wt. 100ml of tin sulfate aqueous solution
At a concentration of 96 wt. 0.5 ml of an aqueous sulfuric acid solution at 0.5% were added. The aqueous solution of tin sulfate was added dropwise to the water in which the nickel hydroxide particles were dispersed, and the mixture was stirred. A concentration of 20 wt. The resulting precipitate was filtered, washed with water and dried by adding 150 ml of a 150% hydrogen peroxide solution little by little, and a tin oxide (SnO ₂ ) layer was formed on a part of the surface. Thus, nickel hydroxide particles (active material particles) on which zinc was coprecipitated were produced. The tin oxide content of the particles was 6% by weight. (Example 5) A nickel-metal hydride secondary battery having the same configuration as that of Example 1 except that the active material particles described below were used for the positive electrode was assembled.

As in Example 1, 50 g of nickel hydroxide particles in which zinc was coprecipitated were dispersed in 600 ml of water. When the concentration is 7.1 wt. 100ml of tin sulfate aqueous solution
At a concentration of 96 wt. 0.5 ml of an aqueous sulfuric acid solution at 0.5% were added. The aqueous solution of tin sulfate was added dropwise to the water in which the nickel hydroxide particles were dispersed, and the mixture was stirred. A concentration of 20 wt. The resulting precipitate was filtered, washed with water and dried by adding 150 ml of a 150% hydrogen peroxide solution little by little, and a tin oxide (SnO ₂ ) layer was formed on a part of the surface. Thus, nickel hydroxide particles (active material particles) on which zinc was coprecipitated were produced. The tin oxide content of the particles was 10% by weight. (Comparative Example 1) Except for use in the positive electrode described below,
A nickel-metal hydride secondary battery having the same configuration as in Example 1 was assembled.

As in Example 1, zinc hydroxide co-precipitated nickel hydroxide particles, cobalt monoxide, carboxymethyl cellulose and water were kneaded at a weight ratio of 100: 5: 0.3: 30 to prepare a paste. . The paste was filled in a sponge-like nickel porous body, dried, rolled, and then a lead was welded to produce a paste-type nickel positive electrode. (Comparative Example 2) Except for use in the positive electrode described below,
A nickel-metal hydride secondary battery having the same configuration as in Example 1 was assembled.

As in Example 1, 3% by weight of tin oxide powder was added to 100% by weight of nickel hydroxide particles in which zinc was coprecipitated, and these were mixed. The obtained mixed powder, cobalt monoxide, carboxymethyl cellulose and water were kneaded at a weight ratio of 100: 5: 0.3: 30 to prepare a paste. The paste was filled in a sponge-like nickel porous body, dried, rolled, and then a lead was welded to produce a paste-type nickel positive electrode.

The obtained secondary batteries of Examples 1 to 5 and Comparative Examples 1 and 2 were charged at room temperature (20 ° C.) at 0.2 CmA and then discharged at 0.2 CmA or 0.1 CmA. The charge / discharge was repeated for 8 cycles to stabilize the charge / discharge characteristics of the battery. Next, the battery was charged at 150% with 0.2 CmA in a high-temperature atmosphere of 60 ° C., left at 20 ° C., and after the temperature of the secondary battery reached 20 ° C., 1.0 C
The discharge capacity at the time of discharging to 1.0 V at mA was measured.
The utilization ratio of the obtained discharge capacity to the theoretical capacity of the positive electrode was calculated, and the result is shown in FIG.

As is apparent from FIG. 2, the current collector has a structure in which a paste containing active material particles containing nickel hydroxide as a main component is filled in a current collector, and the particles contain zinc atoms and tin oxide. The secondary batteries of Examples 1 to 5 assembled from the positive electrodes can improve the utilization rate when charged in a high-temperature atmosphere.
That is, it is understood that the charging efficiency at a high temperature can be improved. On the other hand, the secondary battery of Comparative Example 1 assembled from the positive electrode including the active material particles containing no tin oxide, and Comparative Example 2 assembled from the positive electrode to which tin oxide was added in the form of powder. It can be seen that the secondary battery has a lower utilization factor during high-temperature charging than Examples 1 to 5. (Example 6) A nickel-metal hydride secondary battery having the same configuration as that of Example 1 except that the active material particles described below were used for the positive electrode was assembled.

Silicon dioxide (SiO ₂ ) powder was added to 1 liter of 1N aqueous potassium hydroxide solution heated to 80 to 100 ° C. at a concentration of 0.0002 wt. % And dissolved. To this silicon dioxide solution, 50 g of nickel hydroxide particles in which zinc was coprecipitated as in Example 1, were added little by little. Next, the temperature of the solution was gradually lowered to room temperature to form a silicon dioxide (SiO ₂ ) layer on a part of the surface of the nickel hydroxide particles, thereby producing active material particles. The silicon dioxide content of the particles is 0.1
% By weight. (Example 7) A nickel-metal hydride secondary battery having the same configuration as in Example 1 except that the active material particles described below were used for the positive electrode was assembled.

One liter of a 1 N aqueous solution of potassium hydroxide heated to 80 to 100 ° C. was added with silicon dioxide (SiO ₂ ) powder having a concentration of 0.0031 wt. % And dissolved. To this silicon dioxide solution, 50 g of nickel hydroxide particles in which zinc was coprecipitated as in Example 1, were added little by little. Next, the temperature of the solution was gradually lowered to room temperature to form a silicon dioxide (SiO ₂ ) layer on a part of the surface of the nickel hydroxide particles, thereby producing active material particles. The content of silicon dioxide in the particles was 3% by weight. (Example 8) A nickel-metal hydride secondary battery having the same configuration as that of Example 1 except that the active material particles described below were used for the positive electrode was assembled.

One liter of a 1 N aqueous potassium hydroxide solution heated to 80 to 100 ° C. was mixed with silicon dioxide (SiO ₂ ) powder at a concentration of 0.0031 wt. % And dissolved. To this silicon dioxide solution, 50 g of active material particles obtained in the same manner as in Example 7 were added little by little.
Next, the temperature of the solution was gradually lowered to room temperature to form a silicon dioxide (SiO ₂ ) layer on a part of the surface of the nickel hydroxide particles, thereby producing active material particles. The content of silicon dioxide in the particles was 6% by weight. (Example 9) A nickel-metal hydride secondary battery having the same structure as in Example 1 except that the active material particles described below were used for the positive electrode was assembled.

One liter of a 1 N aqueous solution of potassium hydroxide heated to 80 to 100 ° C. was mixed with silicon dioxide (SiO ₂ ) powder at a concentration of 0.0041 wt. % And dissolved. To this silicon dioxide solution, 50 g of active material particles obtained in the same manner as in Example 8 were added little by little.
Next, the temperature of the solution was gradually lowered to room temperature to form a silicon dioxide (SiO ₂ ) layer on a part of the surface of the nickel hydroxide particles, thereby producing active material particles. The content of silicon dioxide in the particles was 10% by weight. (Comparative Example 3) Except for use in the positive electrode described below,
A nickel-metal hydride secondary battery having the same configuration as in Example 1 was assembled.

As in Example 1, 3% by weight of silicon dioxide powder was added to 100% by weight of nickel hydroxide particles in which zinc was coprecipitated, and these were mixed. The obtained mixed powder, cobalt monoxide, carboxymethyl cellulose and water were kneaded at a weight ratio of 100: 5: 0.3: 30 to prepare a paste. The paste was filled in a sponge-like nickel porous body, dried, rolled, and then a lead was welded to produce a paste-type nickel positive electrode.

With respect to the obtained secondary batteries of Examples 6 to 9 and Comparative Example 3, 0.2 C at normal temperature (20 ° C.) was obtained.
After charging with mA, 0.2CmA or 0.1C
The charging / discharging discharging at mA was repeated eight cycles to stabilize the charging / discharging characteristics of the battery. Then, after charging 150% at 0.2 CmA in a high temperature atmosphere of 60 ° C.,
After the temperature of the secondary battery reaches 20 ° C.,
The discharge capacity at the time of discharging to 1.0 V at 1.0 CmA was measured. The utilization ratio of the obtained discharge capacity to the theoretical capacity of the positive electrode was calculated, and the result is shown in FIG. In FIG. 3,
The results of Comparative Example 1 described above are also shown.

As is apparent from FIG. 3, Examples 6 to 9 were assembled from positive electrodes containing active material particles mainly composed of nickel hydroxide containing zinc atoms and silicon oxides.
It can be seen that the rechargeable battery can improve the charging efficiency at high temperatures. In contrast, the secondary battery of Comparative Example 1 assembled from the positive electrode including the active material particles containing no silicon oxide, and Comparative Example 3 assembled from the positive electrode to which silicon oxide was added in the form of powder. It can be understood that the secondary battery of No. has a lower utilization rate at the time of high-temperature charging as compared with Examples 6 to 9.

[0048]

As described above in detail, according to the present invention, a nickel-metal hydride secondary battery having a high discharge capacity and a long cycle life even in a high-temperature environment can be provided.

[Brief description of the drawings]

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

FIG. 2 shows the secondary batteries of Examples 1 to 5 of the present invention and Comparative Example 1.
6 is a characteristic diagram showing the relationship between the content of the second tin oxide and the utilization rate in the secondary batteries of Nos. 1 to 2.

FIG. 3 is a characteristic diagram showing the relationship between silicon dioxide content and utilization in the secondary batteries of Examples 6 to 9 of the present invention and the secondary batteries of Comparative Examples 1 and 3.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... container, 2 ... positive electrode, 3 ... separator, 4 ... negative electrode, 7 ...
Sealing plate, 8 ... insulating gasket.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Junichi Takabayashi 72 Horikawa-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Inside Toshiba Kawasaki Plant

Claims (2)

[Claims] 1. A positive electrode having a structure in which a paste containing active material particles containing nickel hydroxide as a main component is filled in a current collector, a negative electrode containing a hydrogen storage alloy, and an alkaline electrolyte. The material particles consist of zinc atoms and 4b group elements (Si, G
e, Sn, Pb) at least one oxide and / or
Alternatively, a nickel-hydrogen secondary battery containing a hydroxide. 2. A positive electrode having a structure in which a paste containing active material particles containing nickel hydroxide as a main component is filled in a current collector, a negative electrode containing a hydrogen storage alloy, and an alkaline electrolyte. The material particles contain 1 to 10% by weight of zinc atoms,
And at least one oxide and / or hydroxide among the Group 4b elements (Si, Ge, Sn, Pb) is 0.1 to 10
A nickel-hydrogen secondary battery, characterized in that a layer containing this oxide and / or hydroxide is present on the surface of the active material particles by weight.