JP2003109657A - Nickel-hydrogen secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nickel-hydrogen secondary battery having excellent self-discharging characteristics and charging-discharging cycle life characteristics. SOLUTION: This nickel-hydrogen secondary battery is constituted by sealing an electrode group 5 formed by interposing a synthetic resin separator 3 between a nickel electrode 2 and a hydrogen storage alloy electrode 4, in a battery container 1 together with an alkaline electrolyte. In this case, plasma treatment is applied to the separator 3 in a gas atmosphere containing at least a sulfur element, and the active material of the nickel electrode 2 comprises powder mainly composed of nickel hydroxide, and the high order oxide of cobalt formed at a part or the whole of the surface.

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] TECHNICAL FIELD The present invention relates to a nickel-hydrogen secondary battery.
More specifically, batteries have excellent self-discharge characteristics.
Nickel-hydrogen with excellent charge-discharge cycle life characteristics
Related to secondary batteries. [0002] 2. Description of the Related Art In recent years, portable telephones and portable notebook PCs have been developed.
Of various electronic devices such as
With the progress of molding and weight reduction, secondary batteries as power sources
On the other hand, there is an increasing demand for higher capacity. Conventionally, these
Nickel-cadmium rechargeable batteries as power source for electronic equipment
Have been mainly used. However, the high capacity mentioned above
Demand for nickel-cadmium secondary power
Compatible with pond voltage and nickel cadmium
Since it has higher capacity than secondary batteries,
Indicates that nickel-metal hydride rechargeable batteries have begun to be widely used.
You. However, nickel-hydrogen secondary batteries
Has higher capacity than nickel-cadmium rechargeable battery
However, if you keep it in a high temperature environment while charging it,
There is a problem that discharge easily occurs. Therefore,
The use environment of nickel-hydrogen rechargeable batteries is diversified and harsh conditions
In response to the increasing opportunities used under the
The nickel-hydrogen rechargeable battery must have a high capacity.
Of course, improvement of self-discharge characteristics and charge / discharge cycle life
There is a strong demand for improved characteristics. By the way, nickel-hydrogen secondary batteries are
Generally, a powder of a nickel compound such as nickel hydroxide is used.
The nickel electrode (positive electrode) to be supported and the hydrogen storage alloy powder
Separator between supported hydrogen storage alloy electrode (negative electrode)
To form an electrode group, and this electrode group also serves as the negative electrode terminal.
It is housed in a battery can and further
After injecting the solution, it is manufactured by sealing the battery can.
I have. In such a nickel-hydrogen secondary battery,
That the separator must be electrically insulating
Of course, good wettability with injected alkaline electrolyte
And thereby the liquid retention against the alkaline electrolyte
Is required. Like this
Polyamide fiber with good hydrophilicity
Nonwoven fabrics made of fibers are widely used. [0006] However, this polyamide fiber is
Hydrolysis in potash electrolyte, for example, nitrate ion, nitrite
This produces impurities such as ions and ammonia.
Reduces nickel oxyhydroxide generated on the nickel electrode
Assists the self-discharge reaction at the nickel electrode.
The self-discharge characteristic of the battery is degraded for a long time. like this
Therefore, as the material of the separator,
Fiber material with better oxidation resistance than amide fiber, for example
Polyolefin fiber such as polypropylene fiber or P
Select fluororesin fiber such as TFE fiber,
The use of those which have been subjected to a hydrophilization treatment has been attempted. Specifically, for example, polyolefin fibers
Use nonwoven fabric as anionic, cationic or nonionic surfactant
Surface-treated with a surfactant such as a surfactant
Have been attempted to be used as But
The separator repeats charging and discharging of the battery.
And the surfactant on the surface is released, and the hydrophilicity is reduced.
As a result, the charge-discharge cycle life characteristics will decrease.
Problem. Further, a complete list of nonwoven fabrics of polyolefin fibers
Surface, such as sulfonation, acrylic acid grafting
The treatment adds hydrophilic active groups from outside
Enhances the hydrophilicity of the entire surface of the nonwoven fabric,
Attempts have been made to improve the quality of these processes.
Improvement of self-discharge characteristics is still not enough
Is in a situation that cannot be achieved. Moreover, in the case of these processes,
Since it is necessary to treat the used chemical waste liquid, the separator
If you increase the manufacturing cost, and eventually the battery manufacturing cost,
There is a problem. Further, in addition to the above-mentioned surface treatment,
Fin fiber_Two, N_TwoPlasma treatment using gases such as
By introducing hydrophilic functional groups into this fiber,
(See Japanese Patent Application Laid-Open No. 2001-148237).
See). According to this surface treatment, a considerable degree of self-discharge
It is possible to control
Still inadequate for strong demands on electrical properties
There is a problem that can not be overlooked. On the other hand, the active material of the above-mentioned nickel electrode is
Nickel hydroxide is manufactured using ammonia water during its production.
Since the precipitation reaction is controlled, residual ammonia components
Contains. And this residual ammonia component is
Shuttle reaction in the battery during the battery reaction of the nickel hydrogen battery
Causes the battery to promote self-discharge and self-discharge characteristics
Is deteriorated. By the way, the activity at the nickel electrode described above is considered.
Between materials (nickel hydroxide) and between active material and current collector
When the conductivity between the active material and the body is increased, the utilization rate of the active material increases.
Round. This allows the nickel pole to be incorporated
Charge / discharge cycle life of nickel-metal hydride secondary batteries
Sex is improved. For this reason, the usage rate of active materials is
In order to improve the cycle life characteristics,
Since then, the following methods have been implemented. For example, when preparing a paste of a positive electrode mixture, gold
Genus cobalt, cobalt hydroxide, cobalt trioxide, tetraacid
Cobalt compounds such as tricobalt and cobalt monoxide
A certain amount of particles of a substance or a mixture of
And mix with the nickel hydroxide powder at a specified ratio
And use it as an active material.
It is a way to [0013] The active material powder thus produced is carried.
Nickel electrode used as the positive electrode of alkaline secondary batteries
When incorporated, the metal contained in the active material powder described above
Cobalt and cobalt compounds are both alkaline electrolyzed
Once dissolved in the solution as complex ions, this is the nickel hydroxide
Cover the surface of the powder, and charge the battery for the first time.
These complex ions are oxidized before nickel hydroxide and lead.
High cobalt based on conductive cobalt oxyhydroxide
Nickel hydroxide, which is converted to secondary oxide, which is the active material
Precipitates between the powders and between the active material layer and the current collector;
As it were, a conductive matrix is formed. As a result
Between the active materials and between the active material and the current collector
The conductivity is improved, and the utilization rate of the active material is improved. In addition, the above-described gold in an oxygen-containing atmosphere
Cobalt or cobalt compound and nickel hydroxide powder
While mixing at a fixed rate, simultaneously add an alkaline aqueous solution here
A predetermined amount, and add a
The active material is uniformly heated to a predetermined temperature by irradiating
Methods for producing quality are also known. In this case, the metal
Cobalt and some cobalt compounds are converted to hot alkaline aqueous solution
Dissolves as complex ions, which are the nickel hydroxide powder
Converts to a higher oxide of cobalt while coating the surface
You. Therefore, the active material that has been subjected to the above treatment is
The surface of nickel hydroxide powder
A layer of a higher oxide is formed. [0015] The active material produced by these methods is used.
And the utilization rate of the active material is improved,
It is true that life characteristics are improved. Also,
Strong conductive matrix on the surface of nickel hydroxide powder
The self-reducing property of the nickel electrode itself
Is suppressed. Furthermore, in these manufacturing methods,
During the process, the nickel hydroxide powder is
Is added, the ammonia contained in the nickel hydroxide powder
Part of the near is removed by the alkaline aqueous solution. That
Is generated by residual ammonia component during battery reaction.
The generated shuttle reaction is suppressed, and the self-discharge characteristics of the battery
improves. As described above, the conventional nickel-hydrogen secondary battery
In the case of a pond, the self-discharge characteristics and the charge-discharge cycle life characteristics
Efforts have been made to improve
Satisfactory levels have not yet been achieved.
You. [0017] SUMMARY OF THE INVENTION The present invention relates to a conventional nickel
Solving the above-mentioned problems with hydrogen rechargeable batteries,
Good both discharge characteristics and charge / discharge cycle life characteristics
To provide nickel-hydrogen rechargeable batteries of
You. [0018] Means for Solving the Problems The present inventors have made the above-mentioned description.
In the process of conducting research to achieve the objectives,
Considered treatment to increase the hydrophilicity of the rotator
When the plasma treatment described below is performed, the hydrophilicity of the separator
Is improved, and at the same time,
Parator is present in the battery and causes a shuttle reaction
Also has the ability to capture ammonia
Was. The above separator and the above
Nickel hydroxide with higher cobalt oxides
Manufactured in combination with a nickel electrode that uses powder as the active material
Nickel-hydrogen rechargeable battery has charge-discharge cycle life characteristics
And that the self-discharge characteristics also improved.
To develop the nickel-hydrogen secondary battery of the present invention.
Was. That is, the nickle hydrogen secondary battery of the present invention
Is made of synthetic resin between the nickel electrode and the hydrogen storage alloy electrode.
Electrode group with a separator
Nickel-metal hydride sealed in a battery container with liquid
In the secondary battery, the separator has at least sulfur.
Plasma treatment is performed in a gas atmosphere containing elements.
And the active material of the nickel electrode is nickel hydroxide
Formed mainly on powder and part or all of its surface
Characterized in that it comprises a cobalt higher oxide
You. [0021] DESCRIPTION OF THE PREFERRED EMBODIMENTS Nickel-hydrogen secondary battery of the present invention
Contains at least a sulfur component described later as a separator.
Using plasma treatment in a gas atmosphere,
And the active material of the nickel electrode is manufactured by the method described later.
Except for the use of
There is no difference from the Kel-Hydrogen secondary battery. First, the nickel-hydrogen secondary battery of the present invention
The structure is explained using a cylindrical nickel-hydrogen secondary battery as an example.
I do. In FIG. 1, a cylindrical battery container 1 having a bottom and made of metal is shown.
Include a nickel electrode (positive electrode) 2 described later and a cell described later.
Parator 3 and hydrogen storage alloy electrode (negative electrode) 4 are superposed
The electrode group 5 is formed by spirally winding the rolled sheet.
ing. Then, the negative electrode 4 is disposed on the outermost side of the electrode group 5.
To make electrical contact with the battery container 1 and
The bottom of the group 5 includes an insulating plate 6 disposed on the bottom of the battery container 1.
Is located above. Then, inside the upper opening of the battery container 1,
A ring-shaped insulating gasket 7 is arranged.
A hole 8 is provided at the center with the peripheral edge biting into the
A disk-shaped sealing plate 9 is disposed, and the battery container 1
By caulking to reduce the diameter of the upper opening inward
The sealing plate 9 is connected to the battery container via an insulating gasket 7.
The upper opening 1 is hermetically sealed. The lead terminals 10 are provided above the electrode group 5.
The lead terminal 10 is provided on the sealing plate 9 described above.
It is welded to the lower surface. And the rubber safety valve 11
It is arranged so as to close the central hole 8 of the sealing plate 9,
The cap-shaped positive electrode terminal 12 is
The electrode group is sealed by welding. Also mentioned above
An insulating material having a central hole is provided on the upper part of the battery case 1 having the structure.
Of the positive electrode terminal 12 only from the central hole
Are arranged in a state where they protrude, and the periphery of the holding plate 13 is
Cover the edge, the side and bottom of the battery container 1
The probe 14 is arranged. The battery of the present invention has a cylindrical shape as described above.
It is not limited to a shape.
A rectangular parallelepiped electrode group in which a parator and a negative electrode are alternately stacked
This is housed in a rectangular battery container and sealed.
It may be a prismatic battery. The material of the battery container is
It is not limited to the metals described above,
It may be a lock. Next, the nickel which is the main feature of the battery of the present invention.
The Kell pole and the separator will be described in detail. Electrode group 5
The nickel electrode 2 is generally manufactured as follows. sand
First, the surface of the powder mainly composed of nickel hydroxide is
Having a higher oxide of cobalt formed by the method described
The active material powder and carboxymethylcellulose,
Chill cellulose, sodium polyacrylate, polyteto
Lafluoroethylene, hydroxypropylmethylcellulo
Knead with a binder such as sesame with water to form a viscous paste.
Prepare. The nickel hydroxide used includes Co, C
like u, Zn, Al, Mn, Ca, Mg, Fe, Si
Element may be dissolved. Next, this paste is mixed with, for example, a sponge.
Nickel substrate, reticulated sintered metal fiber substrate or non-woven fabric
Like a felt-plated substrate with nickel plating
After filling and coating the current collector with a three-dimensional network structure,
The paste is dried, and then pressure-molded to a predetermined thickness.
Make the pole sheet. In this case, the current collector
Two-dimensional substrates such as metal and expanded metal
And a structure with burr in the opening of punched metal 2.
A five-dimensional substrate can also be used. Here, a preferred method for producing an active material is described.
explain. First, the starting materials for manufacturing the active material
In an aqueous alkaline solution controlled at pH 11-13
Particles containing nickel hydroxide as the main component are charged, and sulfuric acid is added there.
Hydroxy acid by a method such as gradually adding an aqueous solution of cobalt oxide
A cobalt compound such as cobalt fluoride on the surface of the particles.
A granular material that is applied and covers the surface of the particle; or
Metal cobalt is added to particles mainly composed of nickel hydroxide.
And cobalt hydroxide, cobalt trioxide, tricobalt tetroxide
G, cobalt monoxide, or a mixture of two or more thereof
Granules made by adding particles of cobalt compounds such as compounds
The body is prepared. In this case, the metal powder in the above-mentioned powder and granular material
Content of copper or cobalt compound is 0.5 to 20% by weight
Is preferably set in the range. From 0.5% by weight
If the amount is small, the nickel electrode supporting the obtained active material
The formation of the conductive matrix described above is insufficient
The utilization rate of the active material is not high and
When the amount of nickel hydroxide particles in the active material
To reduce the battery's discharge capacity.
Because it becomes. First, the above-mentioned powder is placed in an alkaline aqueous solution.
The granules are mechanically stirred, and the alkaline aqueous solution and the granules are evenly dispersed.
Mixed together. The alkaline aqueous solution used at this time
Sodium hydroxide aqueous solution, potassium hydroxide aqueous solution
Solution, or a mixture of them, and an aqueous solution of lithium hydroxide
Can be given. At this time, the concentration of the aqueous alkali solution is 1 to 1
It is preferable to set in the range of 4N. Concentration lower than 1N
If it is, the metallic cobalt contained in the granular material
And its solubility in cobalt compounds is low.
The formation of the conductive matrix does not proceed sufficiently,
Because the usage rate cannot be increased much, and from 14N
The higher the concentration, the higher the viscosity of the alkaline aqueous solution becomes.
Do not penetrate sufficiently into the inside of the granular material,
Or cobalt compounds cannot be sufficiently dissolved.
is there. At this time, mixing of the aqueous alkaline solution and the powdery granules
Stirring may be performed at room temperature, but is performed at about 35 to 110 ° C.
The heat treatment may be performed. The above alkaline aqueous solution
In the process of mixing and stirring the powder and granules,
Potassium solution adheres evenly and penetrates inside
As a result, the metallic cobalt contained in the powder
Or a part of cobalt compound dissolves in the alkaline aqueous solution
I will do it. In the present invention, for example,
The above-mentioned mixing of the alkaline aqueous solution
While mixing and stirring, promote more uniform mixing of both.
One, there radiation, preferably microphone from magnetron
The waves are irradiated for about 20 minutes. This microwave is
Irradiate the mixture to mix the aqueous alkaline solution with the granular material.
Water contained in the compound and present around each particle
Vibration of the molecules, thereby uniformly mixing the mixture
Works to heat. And dissolved in an aqueous alkaline solution
Is oxidized in the presence of oxygen.
To form conductive cobalt oxyhydroxide,
It adheres to the surface of nickel hydroxide particles as a component. At this time, mixing of the granular material and the alkaline aqueous solution
Heat treatment temperature of the product should be set in the range of 35 to 160 ° C
Is preferred. If the temperature is lower than 35 ° C,
Alkali of metallic cobalt and cobalt compounds contained
The amount of dissolution in the aqueous solution decreases, and
The utilization of active material is not
Not too high, and higher than 160 ° C
And the structural change occurs in the nickel hydroxide particles themselves
This is because the active material is first deteriorated. The production of the active material was described above.
The method is preferred, but additionally, for example, high cobalt
Secondary oxide is synthesized in advance, and it is
A method of applying it to the surface of nickel hydroxide powder,
Is also good. Next, the negative electrode 4 is made of a hydrogen storage alloy powder and a binder.
And, if necessary, a conductive material such as carbon black.
A paste made by kneading a predetermined amount of electric material with water is used as the current collector.
After filling and application, it is manufactured by drying and molding. The hydrogen storage alloy used is particularly limited.
Hydrogen can be absorbed and released electrochemically
Can be anything, for example, LaN
i_Five, MmNi_Five(Mm is misch metal), LmNi_Five
(Lm is lanthanum-rich misch metal) or Ni
Is partially converted to Al, Mn, Co, Ti, Cu, Zn, Zr,
Multi-element type substituted with Cr, B, etc .; TiNi type,
TiFe-based, MgNi-based or a mixture thereof.
Can be In particular, the following formula: LmNi_xAl_yA
_z(A is at least one selected from Al and Co
X, y, z satisfy 4.8 ≦ x + y + z ≦ 5.4
The hydrogen storage alloy represented by the atomic ratio
Minimizing pulverization during battery life and battery cycle life
It is suitable in that it can improve the characteristics.
You. As the binder, a nickel electrode 2 was used.
The above-mentioned polymer material used at the time of fabrication can be given,
As the current collector, for example, punched metal, expanded
Two-dimensional substrates such as metal, perforated steel plate and nickel net
Or felt-like porous metal, sponge-like metal substrate, etc.
One having a three-dimensional network structure can be given. Of the present invention
A separator 3 incorporated in a nickel-metal hydride secondary battery;
Then, the following is used. First, the separator material is made of synthetic resin.
You. And, as a form of the separator material, non-woven fabric
Although it is preferable that the liquid is in a form,
In the form of a microporous film separator
May be. When the form of the separator material is a nonwoven fabric,
The separator material is made of synthetic resin fibers. In particular,
Polyole such as polyethylene fiber and polypropylene fiber
Fin fibers themselves; the surface of certain polyolefin fibers
Core-sheath structure coated with different kinds of polyolefin fibers
Composite fibers of different types of polyolefin fibers
It is possible to give conjugate fibers that have a split structure.
You. PTFE fibers can also be used,
In the case of, for example, inorganic fiber such as glass fiber is mixed
By doing so, the overall mechanical strength may be increased.
Then, for example, the dry method, the wet method,
By applying the bond method, melt blow method, etc.
Nonwoven fabrics can be manufactured. Then, the form of the separator material is a non-woven fabric.
In some cases, the basis weight is 30 to 70 g / m^TwoBeing
Is preferred. The basis weight is 30 g / m^TwoSmaller nonwoven
Is the electrode group described above because of its low strength as a separator.
May also be damaged during winding when manufacturing, and conversely, 7
0 g / m^TwoIf larger, when the electrode group is manufactured
Of the electrode capacity of the separator increases,
This is because it causes a decrease. The separator material to be used is nitrogen.
Specific surface area measured by elementary BET one-point method
0.5-5.0m^Two/ G.
New Specific surface area is 0.5m^Two/ G separator material
When a filler is used, the liquid retention is reduced and the specific surface area is 5.0.
m^Two/ G separator material has a tensile strength of
The lower the shape retention, the lower the winding
The separator is likely to be damaged during rotation.
You. 1.0-4.0m as separator material^Two/ G
Those having a specific surface area are particularly preferred. Then, the separator material shown in FIG.
Plasma processing using a plasma processing apparatus as shown in
Is performed, the separator 3 is used to manufacture the electrode group 5.
Provided. First, in the case of a plasma processing apparatus to be used, FIG.
As shown in the figure, the earth electrode 16 is
The power electrodes 17 are arranged in parallel at predetermined intervals.
The power electrode 16 is connected to the power supply 8. This ar
Opposing surfaces 16 of the power electrode 16 and the power electrode 17
Both a and 17a are circular with a predetermined diameter.
It is customary. The pressure reducing mechanism 1 is provided in the closed container 15.
9 is connected and the pressure in the closed container 15 is reduced to a predetermined vacuum degree.
I can do it. The closed container 15 has a gas source supply mechanism.
20 is connected, from which a predetermined gas source is
Is supplied into the container, the separator to be treated
The ability to introduce hydrophilic functional groups on the surface of materials
I have. In the present invention, it is carried out using the above-mentioned device.
Gas containing sulfur element as a gas source during plasma processing,
A mixed gas of it and another gas is used. As a gas source containing a sulfur element, for example,
Sulfur monoxide (SO), sulfur dioxide (SO_Two), Sulfur trioxide
Yellow (SO_Three), Disulfur trioxide (S_TwoO_Three) 、 Sulfur heptoxide
(S_TwoO₇) And hydrogen sulfide (H_TwoS). Ma
As the mixed gas, the above-mentioned gas and its dilution
And a mixed gas with the gas used for the treatment. That
As the gas for dilution at the time, for example, O_Two, N_Two,air
And other active gases and inert gases such as Ar and He
Alternatively, they can be used in combination. In particular, the sulfone group is added to the separator material.
Sulfur dioxide and carbonyl that can be introduced into the constituent fibers
Group, carboxyl group. Hydrophilic functional groups such as hydroxyl groups
Oxygen gas introduced into the constituent fibers of the separator material
A gas source containing air is preferred. When operating this device
First, a process is performed between the ground electrode 16 and the power electrode 17.
The separator material 3A to be processed is disposed. Usually Sepa
3A is arranged on the surface of the ground electrode 16.
Then, the pressure reducing mechanism 19 is operated to once pass through the closed container 1.
The pressure is reduced, and a predetermined gas source is further supplied from the gas source supply mechanism 20.
While supplying, the inside of the closed container 1 is, for example, 0.05 to 1 Torr.
Hold at a vacuum of r. Then, the power electrode 17 and the earth
The high-frequency electric field is formed between the two electrodes by operating the
A plasma f is generated between the poles. Specifically, the output power is 5 to 1000 W.
For example, a radio frequency of 13.56 MHz, or
Discharge by microwave at 2.54 GHz and place between electrodes
Low-temperature plasma treatment on the separator material 3A
You. Processing time is preferably set to 0.1 to 30 minutes
No. Parameters of generated plasma under the above conditions
As an example, the electron temperature is 2000-4000 ° K,
Child density 10⁹-10¹³Pieces / cm^Three, Ion temperature 200-40
0 ° K, ion density 10⁹-10¹³Pieces / cm^Three, Plasma sky
The potential between them is 10 to 90V. [0046] EXAMPLES Example 1, Comparative Examples 1-3 (1) Production of separator The following separator was manufactured using the apparatus shown in FIG.
Built. First, a polypropylene fiber with an average fiber diameter of 10 μm
Using a fiber, the basis weight is 50 g / m by the spun-pound method.^Two, Thickness
A non-woven fabric having a thickness of 0.16 mm was produced. This non-woven fabric is 100 mm long and 100 mm wide.
Cut into squares. This nonwoven fabric is grounded with a 90 mm diameter ground electrode.
It was arranged on pole 16 as shown in FIG. That is,
In this case, the entire surface of the ground electrode 16 is
It is covered with. 1 hour in closed container 15
After performing the pressure reduction process, the gas
Supply sulfur gas and oxygen gas at a flow rate of 30 ml / min
The inside of the vessel was adjusted to 13.3 Torr. Then the radio frequency
13.56 kHz, output of power electrode 17 at 50 W for 5 minutes
Plasma treatment was performed. After removing the processed material from the apparatus,
Cut off both ends of a rectangular cell with a width of 40 mm and a length of 100 mm.
Parator. This is referred to as separator A. Also before
The nonwoven fabric described above was subjected to plasma treatment using only oxygen gas.
A separator treated in the same manner except for the above was prepared.
This is designated as separator B. (2) Production of nickel electrode 100 parts by weight of nickel hydroxide powder with an average particle size of 10 μm
On the other hand, 11.1 cobalt hydroxide powder having an average particle size of 1 μm was used.
Parts by weight. This mixed powder is put into a fluidized granulator
While stirring the whole, add 12N sodium hydroxide
Solution at the same time as the magnetron
Irradiation with microwaves, heat treatment at about 100 ° C for 20 minutes
To obtain an active material. To 100 parts by weight of this active material,
0.16 parts by weight of sodium acrylate
Lurose 0.06 parts by weight, carboxymethylcellulose
0.11 parts by weight, PTFE dispersion (specific gravity 1.
5, solid content 60% by weight)
Further, 30 parts by weight of pure water is added, and the whole is kneaded to form a paste.
Was prepared. This paste is filled in a nickel foam substrate.
After drying, roll rolling is performed to a thickness of 0.6 mm.
A nickel electrode was manufactured. This is referred to as a nickel electrode A. one
On the other hand, without subjecting the above mixed powder to the above heat treatment
Same as for Nickel A except that it was used as is.
Thus, a nickel electrode was manufactured. This is called nickel electrode B
I do. (3) Battery assembly On the other hand, when the composition is LmNi_4.0Co_0.04Mn_0.3Al_0.3(L
m is La-enriched misch metal) hydrogen storage alloy machine
Pulverize to powder under 200 mesh (Tyler sieve)
Was. Then, 100 parts by weight of this powder was
0.3 parts by weight of sodium luate, carboxymethylcellulo
0.05 parts by weight, carbon black 1.0 parts by weight, P
TFE departure (specific gravity 1.5, solid content 60
1.0% by weight, and the whole is mixed with 44 parts by weight of water.
A paste was prepared by kneading. [0052] This paste is made of nickel punched metal.
(Opening ratio: 45%), dried and roll-rolled
To produce a 0.3mm thick hydrogen storage alloy electrode (negative electrode)
Was. Table 1 shows the relationship between the nickel electrode and the hydrogen storage alloy electrode.
As shown in the above, sandwich each of the above separators
After making a laminate sheet with the hydrogen storage alloy electrode outside
Then, the various electrode groups 5 shown in FIG. 1 were manufactured. [0053] [Table 1]Then, using these electrode groups 5, an electrolytic solution
As a mixture of 7N KOH and 1N LiOH
AAA size nickel-hydrogen secondary with the structure shown in FIG.
A battery was manufactured. (4) Battery characteristics For each of the obtained batteries, the nominal capacity was reached at a temperature of 20 ° C.
After 150% charge at 0.2C, 1C
A charge / discharge cycle that discharges until the battery voltage reaches 1.0 V
Was repeated three times. After that, charge 150% at 0.2C
And store it in a thermostat at 45 ° C for 14 days
After storage, release the battery until the battery voltage reaches 1.0 V at 1C.
The remaining capacity was measured at that time. The nominal capacity of the battery is C₀, The remaining capacity mentioned above
To C₁And the following equation: 100 × C ₁/ C₀(%) Based
Then, the remaining capacity of each battery was calculated. The result is shown in FIG.
It was shown to. The following is clear from FIG. 1. When comparing Comparative Examples 2 and 3, the nickel electrodes
Even if they are the same, in other words, they have the same active material
In Comparative Example 2 using the separator A, the remaining battery capacity was lower.
Presence is about 3% higher. That is, sulfur dioxide gas and oxygen gas
Plasma treated in a mixed gas atmosphere consisting of
The battery using Parator A is
Better capacity than batteries using plasma-treated separator B
High survival rate. Therefore, the gas atmosphere containing sulfur element
The separator, which has been subjected to plasma treatment in air,
It turns out that it is useful for improving self-discharge characteristics. 2. When Comparative Examples 1 and 3 were compared,
The nickel pole A was used even if the
In Comparative Example 1, the remaining capacity of the battery was about 5% higher. Sand
Having an active material that has been subjected to heat treatment by microwaves
The battery using the nickel electrode A performs the above heat treatment.
Battery with nickel electrode B with active material
High capacity retention rate. From this, the cobalt higher order
Has nickel hydroxide with oxide formed as active material
Nickel electrode is used to improve the self-discharge characteristics of the battery.
It turns out to be useful. 3. When comparing Example 1 with Comparative Example 3,
Of the first embodiment using the nickel electrode A and the separator A
The battery has a remaining capacity of about 10% compared to the battery of Comparative Example 3.
high. In this case, the content of Example 1 with respect to Comparative Example 3
The improvement rate (about 10%) of the residual amount ratio was
The improvement rate (about 3%) of the capacity remaining rate of Comparative Example 2 and the comparative example
Improvement ratio of the remaining capacity ratio of Comparative Example 1 with respect to No. 3 (about 5%)
Is greater than the sum of That is, sulfur source
Separation treated with plasma in a gas atmosphere containing nitrogen
And cobalt hydroxide formed on the surface
Combination with nickel electrode having nickel as active material
If used, expected from using each alone
To improve beyond self-discharge characteristics
Can be Further, for each battery shown in Table 1, 1 C
(-ΔV) and the battery voltage reaches 1.0V at 1C
Repeat the charge / discharge cycle to discharge until each cycle
The time it takes for the battery voltage to reach 1.0V at 1C
The measurement was made to calculate the discharge capacity. And the discharge of Example 1
Cycle when capacity shows 60% of nominal capacity
The number was measured. The number of cycles at this time is a₀(Times)
You. Also, the discharge capacity of each comparative example battery is the nominal capacity.
The number of cycles when a value of 60% was shown was measured. This
In this case, the number of cycles is a (times). And a × 1
00 / a₀Is calculated as the cycle number ratio (%),
The results are shown in FIG. The following is clear from FIG.
You. 4. When Comparative Examples 2 and 3 are compared,
The number ratios are approximately equal. From this, sulfur dioxide gas and acid
Plasma treated in a mixed gas atmosphere with
Using a parator or in an oxygen gas atmosphere.
Even if a separator that has undergone a grit treatment is used, the resulting battery cannot be charged.
It can be seen that the discharge cycle life characteristics are substantially equal. 5. When Comparative Examples 1 and 3 were compared, the separators
Comparative Example 1 using nickel electrode A
However, the cycle number ratio is about 10% larger. That is, micro
Nickel electrode with active material heat-treated by waves
A battery using A is an active material that is not subjected to the heat treatment.
Cycle ratio than battery using nickel electrode B
Is big. From this, the cobalt higher oxide on the surface
Nickel having formed nickel hydroxide as active material
To improve the charge / discharge cycle life characteristics of the battery.
It is found to be useful. 6. When comparing Example 1 with Comparative Example 3,
Of the first embodiment using the nickel electrode A and the separator A
The battery had a cycle number ratio of about 20 compared to the battery of Comparative Example 3.
%high. Then, in this case, the comparison of Comparative Example 3 with Example 1
The improvement ratio of the cycle number ratio (about 20%) is
And the improvement ratio (about 0%) of the cycle number ratio of Comparative Example 2
The improvement ratio of the cycle number ratio of Comparative Example 1 to Comparative Example 3
(About 10%). sand
That is, hydroxyl hydroxide with a cobalt higher oxide formed on the surface
Nickel electrode with nickel as active material and sulfur element
Separator subjected to plasma treatment in a gas atmosphere containing
When combined with, or when each is used alone
Exceeds the expected improvement rate of charge / discharge cycle life characteristics
Thus, the improvement can be achieved. [0062] As is apparent from the above description, the present invention
Nickel-hydrogen secondary batteries have good self-discharge characteristics
High capacity retention rate even when stored for a long time at high temperature
And, as is clear from FIG.
Excellent life characteristics. In other words, self-discharge characteristics and charge / discharge
All of the electric cycle life characteristics are excellent.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially cutaway perspective view showing a cylindrical nickel-metal hydride secondary battery incorporating a separator and a nickel electrode of the present invention. FIG. 2 is a schematic diagram showing a plasma processing apparatus. FIG. 3 is a graph showing a remaining capacity ratio of each battery of an example and a comparative example. FIG. 4 is a cycle number ratio (%) of each battery of an example and a comparative example.
FIG. [Description of Signs] 1 Battery container 2 Nickel electrode (positive electrode) 3 Separator 3A Separator material 4 Hydrogen storage alloy electrode (negative electrode) 5 Electrode group 6 Insulating plate 7 Insulating gasket 8 Hole 9 Sealing plate 10 Lead terminal 11 Safety valve 12 Positive terminal 13 Holding plate 14 Outer tube 15 Airtight container 16 Earth electrode 17 Power electrode 18 Power supply 19 Decompression mechanism 20 Gas source supply mechanism

   ────────────────────────────────────────────────── ─── Continuation of front page    F term (reference) 4L031 CB05 DA00 DA08                 5H028 AA05 BB06 BB10 EE05 EE10                       FF04 FF05                 5H050 AA07 AA09 BA14 CA03 CB17                       DA10 DA19 EA12 EA16 EA21                       GA01 GA10 GA21 GA22

Claims (1)

Claims 1. An electrode group in which a separator made of a synthetic resin is interposed between a nickel electrode and a hydrogen storage alloy electrode is sealed in a battery container together with an alkaline electrolyte. In the nickel-hydrogen secondary battery, the separator is subjected to plasma treatment in a gas atmosphere containing at least a sulfur element, and the active material of the nickel electrode is a powder mainly composed of nickel hydroxide,
A nickel-hydrogen secondary battery comprising a cobalt higher oxide formed on part or all of the surface thereof.