JP2975701B2 - Method for manufacturing metal hydride storage battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a metal hydride battery having a negative electrode comprising a hydrogen storage alloy capable of reversibly storing and releasing hydrogen.

[0002]

2. Description of the Related Art Conventionally, an alkaline storage battery such as a nickel-cadmium storage battery or a lead storage battery has been widely used as a power source for various electric appliances. In recent years, attention has been focused on metal hydride storage batteries using a hydrogen storage alloy, which is lighter, has higher capacity, and has a higher energy density than these batteries, as a negative electrode. This kind of metal hydride storage battery, which has a negative electrode made of a hydrogen storage alloy that reversibly stores and releases hydrogen and a positive electrode that uses a metal oxide as an active material, has a problem that the initial capacity is low and the capacity variation is large. is there.

[0003] When charged and discharged in an alkaline electrolyte, the hydrogen storage alloy absorbs and releases hydrogen as an active material, and the absorption and release of hydrogen deforms the alloy lattice, causing the hydrogen storage alloy to be pulverized. There has been a problem that the electrode drops off from the electrode to cause a reduction in capacity, and the mechanical strength and conductivity of the electrode are significantly reduced.

As a countermeasure against this, Japanese Patent Laid-Open Publication No. 61-99277
Japanese Patent Application Laid-Open Publication No. H11-15083 proposes that the amount of the electrolyte solution be regulated to prevent the hydrogen storage alloy from falling off due to pulverization and deterioration in capacity.

[0005] However, even if the amount of the electrolyte is regulated, the hydrogen storage alloy electrode has poor electrolyte permeability, and the electrolyte is very slowly diffused uniformly in the battery. Therefore, there are places where the electrolyte does not penetrate into the surface of the hydrogen storage alloy electrode,
There was a problem that the internal resistance of the battery increased.

[0006]

SUMMARY OF THE INVENTION According to the present invention, an attempt is made to solve the above-mentioned problems and to obtain a sufficient battery capacity from the beginning of a battery cycle by uniformly diffusing an electrolytic solution inside the battery. Is what you do.

[0007]

In the manufacturing method according to the present invention, in order to solve the problems], a negative electrode comprising a hydrogen absorbing alloy, a positive electrode, method of manufacturing a metal hydride storage battery comprising an electrolytic solution, an electrolytic solution
After injection, the battery can was sealed and sealed to assemble the battery.
Thereafter, a method of diffusing the electrolyte inside the battery includes a diffusion step by at least one of ultrasonic vibration, heating, and rotation.

In the diffusion step, the wavelength of the vibration by the ultrasonic wave is 30 kHz or more, the temperature for heating the battery is 60 ° C. or more and 100 ° C. or less, and the number of rotations for rotating the battery is 100 rpm. p. m. It is preferable that the rotation speed is not less than 1000 rotations.

[0009]

According to the present invention, the electrolytic solution in the battery can be uniformly diffused by performing a process of diffusing the electrolytic solution such as vibration by ultrasonic waves, heating treatment, and rotation treatment on the completed battery. As a result, it is possible to prevent an increase in the internal resistance of the battery caused by the non-uniformity of the electrolyte and the deterioration of the alloy due to the local reaction of the hydrogen storage alloy electrode, that is, the deterioration of the hydrogen storage alloy electrode characteristics. Therefore, 100% of the nominal capacity can be discharged from the initial charge and discharge of the cycle.

[0010]

EXAMPLES (Experiment 1) Commercially available misch metal Mm (L
a, a mixture of rare earth elements such as Ce, Nd and Pr), N
i, Co and Al have a constant element ratio, Mm: Ni: Co:
Weigh and mix so that Al becomes 1: 3: 1.5: 0.5.

Next, this mixture was heated and melted in an argon arc melting furnace to produce an alloy having a composition of MmNi ₃ Co _1.5 Al _0.5 .

Next, the alloy was reduced to a fine powder of 50 μm or less by ordinary mechanical pulverization. Polytetrafluoroethylene (PTFE) as a binder is added to this fine powder.
Add the dispersion, mix uniformly and add water to make a paste.

The paste was pressed onto both surfaces of a nickel-plated punched metal current collector to produce a hydrogen storage alloy negative electrode.

The negative electrode made of this hydrogen storage alloy and a well-known sintered nickel positive electrode are spirally wound through a nonwoven fabric separator to form an electrode body, which is inserted into a battery can. 3.0 g of an electrolytic solution with an aqueous potassium hydroxide solution was injected. After the injection of the electrolyte, the battery can was sealed and completely sealed to produce a metal hydride storage battery.

(Example 1) The metal hydride storage batteries obtained in Experiment 1 were subjected to shocks of ultrasonic waves of 30 kHz, 50 kHz and 100 kHz for 10 minutes to obtain batteries A, B and C of the present invention, respectively.

(Comparative Example 1) The metal hydride storage batteries obtained in Experiment 1 were subjected to an ultrasonic shock of 10 kHz and 20 kHz for 10 minutes to obtain comparative batteries O and P, respectively. A battery that does not give any impact is referred to as a comparative battery Q.

The initial battery capacities of the batteries A, B and C of the present invention and the comparative batteries O, P and Q are measured. As measurement conditions, the battery is charged at a current of 0.1 C for 12 hours in an atmosphere of 25 ° C., and then discharged at a current of 0.5 C until the battery voltage reaches 1.0 V. The above results are shown in FIG.

As is apparent from FIG. 1, the initial capacity of the comparative battery Q is 60% of the nominal capacity.
B and C can exhibit 100% of the nominal capacity from the beginning.

FIG. 2 shows the relationship between the number of cycles and the discharge capacity of batteries A, B and C of the present invention and comparative batteries O, P and Q.

The measuring conditions were the same as those described above. 1 and 2, the batteries A, B and C of the present invention have a discharge capacity of 100% from the initial cycle, and the discharge capacity is stable even if the number of cycles is advanced.

This is because the electrolyte in the battery can be uniformly diffused by applying ultrasonic vibration having a wavelength of 30 kHz or more after the fabrication of the battery, and the penetration of the electrolyte into the hydrogen storage alloy can be accelerated. As a result, there is no portion where the electrolyte is not wetted, and an increase in the internal resistance of the battery due to the portion can be prevented, and the characteristics of the hydrogen storage alloy electrode can be sufficiently exhibited.

FIG. 3 shows the results of the liquid volume distribution in the positive electrodes, negative electrodes and separators of the batteries A, B and C of the present invention and the comparative batteries O, P and Q.

From FIG. 3, it can be seen that the batteries A, B and C of the present invention have the electrolyte dispersed uniformly.

(Experiment 2) (Example 2) The metal hydride storage battery obtained in Experiment 1
C, 80 ° C and 100 ° C in a thermostat for 1 hour,
Inventive batteries D, E and F, respectively.

(Comparative Example 2) The metal hydride storage batteries obtained in Experiment 1 were heated in constant temperature baths at 40 ° C, 120 ° C and 140 ° C for 1 hour to obtain comparative batteries R, S and T, respectively. A battery not heated is referred to as a comparative battery U.

The initial battery capacities of the batteries D, E, and F of the present invention and the comparative batteries R, S, T, and U by charging and discharging are measured. The measurement conditions are as follows.
After charging for 12 hours with a current of C, the battery is discharged at a current of 0.5 C until the battery voltage reaches 1.0 V. The results are shown in FIG.

As is apparent from FIG. 4, the comparative battery U has an initial capacity of 60% of the nominal capacity.
In E and F, 100% of the nominal capacity can be exhibited from the beginning.

FIG. 5 shows the relationship between the number of cycles and the discharge capacity of the batteries D, E and F of the present invention and the comparative batteries R and U.
The measurement conditions are the same as in Experiment 1.

FIG. 6 shows the batteries D, E and F of the present invention.
5 shows the results of the liquid amount distribution in the positive electrode, the negative electrode, and the separator of Comparative Batteries R and U.

From FIGS. 4, 5 and 6, the batteries D and E of the present invention are shown.
And F show the same effect as Experiment 1. This indicates that the diffusion of the electrolytic solution in the battery due to the heating and the wettability to the hydrogen storage alloy have the same diffusion effect as that of the method using the ultrasonic vibration.

With respect to the heating at 120 ° C. or higher, if the temperature is higher than 120 ° C., the electrode is deteriorated due to the decomposition of the electrode binder and the surfactant used for the separator, so that the capacity is reduced at the beginning of the cycle.

(Experiment 3) The metal hydride storage battery obtained in Experiment 1 was used for 50 r. p. m. , 100r. p. m, 500r.
p. m. And 1000r. p. m. And the electrolyte solution in the battery was diffused.

FIG. 7 shows the relationship between the total number of rotations at each rotation speed and the initial discharge capacity.

As shown in FIG. p. m. Above 10
By performing the rotation over 00 rotations, the initial discharge capacity becomes 100
% Discharge becomes possible.

Next, at 500r. p. m. Battery G of the present invention rotated 2000 times at 500 r. p. m. At 500 r. p. m. FIG. 8 shows the relationship between the number of cycles and the discharge capacity of the comparative battery W rotated 2000 times in FIG.
And FIG.

From FIGS. 7, 8 and 9, 100 r. p.
m. Thus, it is considered that the battery that has been rotated 1000 times or more has the same diffusion effect as in Experiments 1 and 2.

[0037]

According to the present invention, in the method for manufacturing a metal hydride storage battery, the electrolyte in the metal hydride storage battery can be uniformly diffused, and a discharge of 100% of the nominal capacity is performed in the initial charge and discharge of the battery. It is possible, and its industrial value is extremely large.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the initial discharge capacity of a battery and the change in the wavelength of ultrasonic vibration.

FIG. 2 is a diagram showing the relationship between the number of cycles and the discharge capacity of a battery that has undergone a diffusion step by ultrasonic vibration.

FIG. 3 is a diagram showing a liquid amount distribution of a battery that has been subjected to a diffusion step by ultrasonic vibration.

FIG. 4 is a diagram showing a relationship between an initial discharge capacity of a battery and a temperature change given to the battery.

FIG. 5 is a diagram showing the relationship between the number of cycles and the discharge capacity of a battery that has undergone a temperature diffusion step.

FIG. 6 is a diagram showing a liquid amount distribution of a battery that has undergone a temperature-based diffusion step.

FIG. 7 is a diagram showing the relationship between the total number of rotations at each rotation number and the initial discharge capacity of the battery.

FIG. 8 is a diagram showing the relationship between the number of cycles and the discharge capacity of a battery that has undergone a diffusion process by rotation.

FIG. 9 is a diagram showing a liquid amount distribution of a battery that has been subjected to a diffusion process by rotation.

──────────────────────────────────────────────────続 き Continued on the front page (72) Motohiro Miki 2-18-18 Keihanhondori, Moriguchi City Sanyo Electric Co., Ltd. (56) References JP-A-3-53448 (JP, A) JP-A-59-134558 (JP, A) (58) Fields surveyed (Int. Cl. ⁶ , DB name) H01M 2/36-2/38 H01M 10 / 04,10 / 28,10 / 34

Claims (2)

(57) [Claims] 1. A negative electrode comprising a hydrogen storage alloy, a positive electrode,
In a method for producing a metal hydride storage battery comprising an electrolyte, after injecting the electrolyte, the battery can is sealed and sealed to close the battery.
A method of manufacturing a metal hydride storage battery, comprising a diffusion step by at least one of ultrasonic vibration, heating and rotation as a method of diffusing the electrolyte solution inside the battery after assembling . 2. In the diffusion step, the wavelength of vibration by ultrasonic waves is 30 kHz or more, the temperature for heating the battery is 60 ° C. or more and 100 ° C. or less, and the number of rotations for rotating the battery is 100 rpm. p. m. The method for producing a metal hydride storage battery according to claim 1, wherein the rotation speed is not less than 1000 rotations.