JPH11297318A - Paste filling device, and manufacture of alkaline secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paste filling device capable of filling a paste into a substrate, without generating filling nonuniformity and dispersion, and capable of enhancing the filling amount. SOLUTION: This device is provided with a container 1 for storing a paste, a substrate insertion port 2 formed in a bottom of the container 1, and plural rollers arranged rotatably inside the container 1. At least two rollers 4a, 4b from among the rollers are arranged to be separated by the substrate inserted from the insertion port 2 into the container 1, and to make acute an angle θformed by a line joining both centers of the rollers 4a, 4b and the substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a paste filling apparatus and a method for manufacturing an alkaline secondary battery.

[0002]

2. Description of the Related Art An alkaline secondary battery includes a nickel-cadmium secondary battery including a positive electrode containing nickel hydroxide as an active material, a negative electrode containing cadmium hydroxide and an alkaline electrolyte, and the above-mentioned cadmium hydroxide. A nickel-hydrogen secondary battery using a negative electrode containing a hydrogen storage alloy instead of the negative electrode is known.

[0003] In alkaline secondary batteries, high capacity is demanded along with the reduction in weight and size of portable electronic devices and the like. In the alkaline secondary battery, since the capacity regulating electrode is the positive electrode, it is necessary to increase the positive electrode active material to increase the positive electrode capacity in order to satisfy the demand for higher capacity.

A paste-type positive electrode is prepared by kneading a conductive agent such as nickel hydroxide powder and a cobalt compound and a binder (eg, carboxymethylcellulose, polytetrafluoroethylene) as an active material in the presence of water. Is prepared, and the paste is filled in a conductive substrate having a three-dimensional structure such as a sponge-like porous metal body, dried, and press-molded.

In order to increase the amount of the positive electrode active material, it is necessary to increase the paste filling amount. Conventionally, the paste is filled by brush application or by placing a pair of rotatable rollers facing each other in a container containing the paste and passing the substrate between the rollers.

[0006]

However, application by brush has a problem in continuity. On the other hand, according to the above-described method of passing the substrate through the container containing the paste, the substrate is pressed by the rollers from both sides when filling the paste, so that the air in the substrate is smoothly replaced with the paste. However, there is a problem that air remains in the substrate to cause uneven filling, and it is difficult to further increase the paste filling amount.

An object of the present invention is to provide a paste filling apparatus which can fill a paste without unevenness in filling a paste on a substrate and can improve the filling amount.

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-capacity alkaline secondary battery which can be filled with a paste of at least one of the positive electrode and the negative electrode in a sufficient amount without unevenness without filling the substrate. It is intended to provide a manufacturing method.

[0009]

According to the present invention, there is provided a paste filling apparatus comprising: a container for accommodating a paste; a substrate insertion opening formed at the bottom of the container; And at least two of the rollers are separated by a substrate inserted into the container from the substrate insertion port, and an angle between a line connecting the centers and the substrate becomes an acute angle. It is characterized by being arranged as follows.

In the method for manufacturing an alkaline secondary battery according to the present invention, in the step of filling the positive electrode or the negative electrode, the substrate passes between two rotatable rollers disposed in a container containing the paste, and An angle between a line connecting the centers of the rollers and the substrate is an acute angle.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A paste filling apparatus according to the present invention will be described below with reference to FIG.

As shown in FIG. 1, the paste filling device comprises:
A paste storage container (hopper) 1 having a box shape and having a tapered bottom is provided. A slit 2 as a substrate insertion port is formed on the bottom surface of the container 1. A feed roller 3 for transporting the band-shaped substrate S to the paste container 1 is disposed below the paste container 1. The two rotatable rollers 4a and 4b are positioned separately on one surface side and the other surface side of the band-shaped substrate S when the band-shaped substrate S is inserted into the container 1 from the slit 2. The angle θ between a straight line L connecting the centers of the rollers 4a and 4b and the coating surface of the belt-shaped substrate S is set to be an acute angle.

Preferably, the angle θ is 30 to 60 °. If the angle θ falls outside the above range, it may be difficult to improve the paste filling rate in the substrate.

Each of the rollers 4a and 4b and the belt-like substrate S
Is preferably 0 to 5 mm. By setting the distance X within the above range, the paste filling rate can be further improved. When the distance X exceeds 5 mm, the force of the roller to insert the paste into the belt-like substrate is weakened, so that the paste filling rate may decrease. A more preferable range of the distance X is 3 mm or less. A more preferred range is 1 mm or less.

Hereinafter, a method of manufacturing an alkaline secondary battery using the paste filling apparatus will be described.

First, an example of an alkaline secondary battery (for example, a cylindrical alkaline secondary battery) manufactured by the method according to the present invention will be described with reference to FIG.

That is, in the bottomed cylindrical container 11,
An electrode group 15 produced by laminating the positive electrode 12, the separator 13, and the negative electrode 14 and winding them in a spiral shape is accommodated. The negative electrode 14 is arranged at the outermost periphery of the electrode group 15 and is in electrical contact with the container 11. The alkaline electrolyte is contained in the container 11. A circular first sealing plate 17 having a hole 16 in the center is
It is arranged in the upper opening of the container 11. The ring-shaped insulating gasket 18 is disposed between the peripheral edge of the sealing plate 17 and the inner surface of the upper opening of the container 11, and the container 11 is caulked to reduce the diameter of the upper opening inward.
The sealing plate 17 is hermetically fixed via the gasket 18. The positive electrode lead 19 has one end connected to the positive electrode 12.
The other end is connected to the lower surface of the sealing plate 17. The positive electrode terminal 20 having a hat shape is mounted on the sealing plate 17 so as to cover the hole 16. A rubber safety valve 21 is disposed in a space surrounded by the sealing plate 17 and the positive electrode terminal 20 so as to close the hole 16. Circular holding plate 2 made of an insulating material having a hole in the center
2 is arranged on the positive electrode terminal 20 so that the projection of the positive electrode terminal 20 protrudes from the hole of the holding plate 22. The outer tube 23 covers the periphery of the holding plate 22, the side surface of the container 11, and the bottom periphery of the container 11.

Next, the positive electrode 12, the negative electrode 14, the separator 13, and the alkaline electrolyte will be described.

1) Positive electrode 12 This positive electrode 12 is manufactured by using the above-described paste filling apparatus shown in FIG.

First, a paste is prepared by adding a conductive agent and a binder to nickel hydroxide powder and kneading them in the presence of water. The paste is stored in the paste storage container 1, and the two rollers 4a and 4b are rotated in opposite directions. Subsequently, the belt-shaped substrate S is transported to the slit 2 of the container 1 by the feed roller 3 and inserted into the container 1 from the slit 2. First, by pressing the band-shaped substrate S from the left side with the roller 4a, the paste can be filled while extruding the air in the substrate S to the outside. Next, since the belt-shaped substrate S is pressed from the right side by the roller 4b,
As before, the paste can be filled while extruding air from the substrate. By passing the band-shaped substrate S between the two rollers 4a and 4b which are not opposed to each other, the band-shaped substrate S can be uniformly and uniformly filled with the paste. The filling rate can be improved. Subsequently, the positive electrode can be manufactured by drying the substrate filled with the paste and performing pressure molding.

It is preferable that the rotation speed of each of the rollers 4a and 4b is higher than the transport speed (passing speed) of the belt-shaped substrate S. This is because if the transport speed of the belt-shaped substrate S is higher, the paste filling rate in the substrate may be reduced. It is preferable that the rotation speed of each of the rollers is at least ten times the transport speed of the belt-shaped substrate. However, even if the rotation speed is higher than 100 times the transport speed, it is not possible to expect the paste filling rate to be improved in proportion to the increase in the speed, so that productivity may be reduced. Therefore, the rotation speed is preferably set to 10 to 100 times the transport speed. A more preferred range is 30 to 100 times.

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

As the conductive agent, at least one selected from a cobalt compound and metallic cobalt can be used. Examples of the cobalt compound include cobalt monoxide and cobalt hydroxide.
The conductive agent may be added to the paste by being attached to the surface of the powder or the nickel hydroxide powder as a layer.

Examples of the binder include polytetrafluoroethylene, carboxymethylcellulose, methylcellulose, sodium polyacrylate, and polyvinyl alcohol.

The substrate S is preferably a conductive substrate having a three-dimensional structure. For example, a three-dimensional substrate having a sponge-like, fibrous, felt-like porous structure made of a metal such as nickel or stainless steel or a nickel-plated resin, a metal such as nickel or stainless steel, or a nickel-plated metal is used. A two-dimensional substrate having a network structure made of a resin or the like and a composite substrate made of the three-dimensional substrate.

2) Negative Electrode 14 The negative electrode 14 is prepared by, for example, kneading a negative electrode active material, a conductive material and a binder together with pure water to prepare a paste, applying the paste to a conductive substrate, and drying the paste. It is manufactured by rolling and forming. The application of the paste to the conductive substrate may be performed using the paste filling device described above.

Examples of the negative electrode active material include cadmium compounds such as metal cadmium and cadmium hydroxide, and hydrogen. Examples of the host matrix of hydrogen include a hydrogen storage alloy. Among them, the hydrogen storage alloy is preferable because the capacity of the secondary battery can be improved as compared with the case where the cadmium compound is used. As the hydrogen-absorbing alloy, for example, the general formula _{(1); LmNi w Co x} Mn y Al z ( atomic ratio w, x, y, the total value of z is 5.00 ≦ w + x + y + z ≦
Having composition represented by 5.50 in which), the general formula (2); AB _x (where, A is Ti and / or Zr, B consists either Mn alone or a Mn, N
i, V, Co, Cr, Al, Fe, Cu, Mo, La,
One or more elements selected from Ce, Pr and Nd, wherein x represents 1.8 ≦ x ≦ 2.5), and the main component of the alloy phase is a C14 or C15 Laves phase And the like.

Examples of the conductive material include carbon black and graphite.

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

Examples of the conductive substrate include a two-dimensional substrate such as a punched metal, an expanded metal, and a nickel net.

3) Separator 13 Examples of the separator 13 include a nonwoven fabric made of a polyamide fiber and a nonwoven fabric made of a polyolefin fiber such as polyethylene or polypropylene provided with a hydrophilic functional group.

4) Alkaline Electrolyte As the alkaline electrolyte, for example, an aqueous solution of sodium hydroxide (NaOH), lithium hydroxide (LiOH)
Aqueous solution, potassium hydroxide (KOH) aqueous solution, NaO
H and LiOH mixed solution, KOH and LiOH mixed solution, K
A mixed solution of OH, LiOH, and NaOH can be used.

As described above, the paste filling apparatus according to the present invention comprises a container for accommodating a paste, a substrate insertion opening formed at the bottom of the container, and a plurality of rotatable plural units arranged in the container. And a roller, wherein at least two of the rollers are separated by a substrate inserted into the container from the substrate insertion port, and an angle between a line connecting the centers and the substrate is an acute angle. Is characterized by being arranged in a. When a substrate is inserted from a substrate insertion port of a paste container of such an apparatus, at least two rollers are arranged in the container at a desired distance from each other and in a state where they are not opposed to each other. Since the substrate can be passed, the substrate can be filled with the paste while pressing the substrate from one side to push out the air in the substrate to the outside.
As a result, uneven filling can be prevented, so that the paste filling rate in the substrate (particularly, a substrate having a three-dimensional structure) can be improved.

By arranging the at least two rollers in the container such that the distance to the substrate is 0 to 5 mm, the substrate can be sufficiently pressed by the rollers. Can be further increased.

In the step of filling the positive electrode or the negative electrode in the method of manufacturing an alkaline secondary battery according to the present invention, the substrate passes between two rotatable rollers disposed in a container containing the paste; An angle between a line connecting the centers of the rollers and the substrate is an acute angle. According to such a method, since the two rollers are arranged asymmetrically via the substrate, the substrate can be pressed from one side by the rollers, and the paste is filled while extruding air in the substrate. It is possible to fill the substrate (particularly, a substrate having a three-dimensional structure) with the paste at a high density. By drying this and subjecting it to pressure molding, a high-capacity positive electrode or negative electrode can be manufactured, and a high-capacity alkaline secondary battery can be manufactured from the obtained positive electrode or negative electrode.

The distance between the roller and the substrate is 0 to 5 m
By setting m, the substrate can be sufficiently pressed by the roller, so that the paste filling rate in the substrate can be further increased.

Further, by making the rotation speed of the roller higher than the passing speed of the substrate, the paste filling rate in the substrate can be further increased.

In FIG. 1 described above, an example is described in which the number of rollers arranged asymmetrically via the substrate is two. However, the number of rollers is not limited to two but may be three or more. be able to. Also, as a feed roller for substrate transport,
One or more pairs of rollers may be arranged in the paste container so as to face each other at a desired distance.

In FIG. 2 described above, a separator is interposed between the positive electrode and the negative electrode, and an electrode group produced by spirally winding the separator is housed in the container.
For example, a laminate made by alternately stacking a positive electrode and a negative electrode with a separator interposed therebetween may be housed in a bottomed rectangular cylindrical container.

[0040]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

Example 1 <Preparation of Positive Electrode> A mixed powder composed of 90 parts by weight of nickel hydroxide powder and 10 parts by weight of cobalt oxide powder was mixed with 3 parts by weight of carboxymethyl cellulose and polytetrafluoroethylene with respect to the nickel hydroxide powder. A paste having a viscosity of 10 to 40 dPa · s was prepared by adding 5 parts by weight of fluoroethylene, further adding 45 parts by weight of pure water and kneading them.

On the other hand, in the paste filling apparatus shown in FIG. 1 described above, the two rotatable rollers 4a and 4b are coated on the strip-shaped substrate S when the strip-shaped substrate S is conveyed from the slit 2 into the paste container 1. Work surface and the rollers 4a, 4
b was arranged so that the angle θ formed by a straight line L connecting the centers of b was 20 °. The distance X between each of the rollers 4a, 4b and the substrate S was 0.05 mm.

The paste was contained in the paste container 1, and the roller 4a was rotated clockwise and the roller 4b was rotated counterclockwise at an angular speed of 32 rad / s. Continuing, the thickness of the band-shaped substrate S is 1.1 mm.
Then, a nickel-plated fiber substrate having a porosity of 95% was transported by the feed roller 3 to the slit 2 of the container 1 at a transport speed of 1.0 m / min. Here, each of the rollers 4
Since the diameters of a and 4b are 40 mm, the angular velocity is converted to a velocity of 38 m / min, which is equivalent to 38 times the transport velocity. First, the band-shaped substrate S inserted into the container 1 from the slit 2 is
The paste was filled while a pressure was applied from the left side by a to push out the air inside. Next, the band-shaped substrate S was pressed from the right side by the roller 4b, and the paste was filled while extruding the internal air in the same manner as described above. The substrate filled with the paste as described above was dried, and subjected to pressure molding by a roller press to produce a paste-type positive electrode.

<Preparation of Negative Electrode> A hydrogen storage alloy having a composition of LmNi _4.0 Co _0.4 Mn _0.3 Al _0.3 was prepared using a lanthanum-enriched misch metal Lm and Ni, Co, Mn, and Al by a high frequency furnace. The hydrogen absorbing alloy was mechanically pulverized, and 0.5 parts by weight of sodium polyacrylate, 0.125 parts by weight of carboxymethylcellulose (CMC), and a dispersion of polytetrafluoroethylene were solidified with respect to 100 parts by weight of the obtained alloy powder. A paste was prepared by adding 1.5 parts by weight, 1 part by weight of carbon powder and 50 parts by weight of water in terms of minutes and kneading. This paste was applied to a punched metal, dried, and then pressed to form a paste-type negative electrode.

Next, a separator made of a polypropylene non-woven fabric subjected to a hydrophilic treatment was interposed between the positive electrode and the negative electrode, and spirally wound to form an electrode group. This electrode group is housed in a cylindrical metal container having a bottom, an alkaline electrolyte containing potassium hydroxide as a main component is injected, and an AA size using a metal cover or the like is used, and the theoretical capacity is 1200 mA.
h. A cylindrical nickel-metal hydride secondary battery was manufactured.

(Examples 2 to 4) The angle θ between the straight line L connecting the centers of the rollers 4a and 4b and the belt-shaped substrate S is set to each value (30
{, 45 ° and 60 °), except that a cylindrical nickel-metal hydride secondary battery was manufactured in the same manner as in Example 1.

(Comparative Example 1) <Preparation of Positive Electrode> When the band-shaped substrate is transported into the paste container, two rotatable rollers face each other via the band-shaped substrate (a straight line connecting the centers of the rollers). The paste was filled using a paste filling device arranged such that the angle between the substrate and the coating surface of the substrate was 90 °. The distance between each roller and the substrate and the diameter of each roller were the same as in Example 1.

A paste having the same composition as that described in Example 1 is accommodated in the paste container of the paste filling apparatus, and one roller is rotated clockwise and the other roller is rotated counterclockwise as described in Example 1. It was rotated at the same angular velocity as it did. Subsequently, when a nickel-plated fiber substrate similar to that described in Example 1 is transported by the feed roller to the slit of the container at a transport speed similar to that described in Example 1, the two rollers disposed opposite to each other are moved. The paste was filled in the substrate while the substrate was pressed from both sides by the two rollers. The substrate filled with the paste as described above was dried, and subjected to pressure molding by a roller press to produce a paste-type positive electrode.

A cylindrical nickel-metal hydride secondary battery was manufactured in the same manner as in Example 1 except that the obtained positive electrode was used.

With respect to the obtained secondary batteries of Examples 1 to 4 and Comparative Example, the filling ratio of the positive electrode in the substrate was measured, and the results are shown in FIG.

As is apparent from FIG. 3, the secondary batteries of Examples 1 to 4 have a positive electrode paste filling rate of 96%, 98%,
98%, 98%, 86% positive electrode paste filling rate
This is higher than the secondary battery of Comparative Example.

The secondary batteries of Examples 1 to 4 and Comparative Example were charged at room temperature at 0.1 C for 1 hour.
After charging at 0.5C until it reaches 150%,
The first charge / discharge was performed by discharging at 0.2 C to 1 V. Subsequently, at room temperature, the battery was charged at 1 C for 1.5 hours, and then discharged and charged at 1 C to a battery voltage of 1 V three times. The discharge capacity at the third cycle was measured, and the results are shown in Table 1 below.

[0053]

[Table 1] As is clear from Table 1, the secondary batteries of Examples 1 to 4 have higher discharge capacities than the secondary batteries of Comparative Examples.

(Examples 5 to 10) The distance X between each of the rollers 4a and 4b and the substrate S was set to a value (0 mm, 0.5 mm,
1.0mm, 3.0mm, 5.0mm and 7.0mm)
A cylindrical nickel-metal hydride secondary battery was manufactured in the same manner as in Example 1 except for the following.

With respect to the obtained secondary batteries of Examples 5 to 10,
The filling rate of the positive electrode in the substrate was measured, and the results are shown in FIG.

As is apparent from FIG. 4, the secondary batteries of Examples 5 to 10 have positive electrode paste filling rates of 98% and 98%, respectively.
%, 98%, 97%, 92% and 81%.

The discharge capacities of the secondary batteries of Examples 5 to 10 were measured in the same manner as described above, and the results are shown in Table 2 below.

[0058]

[Table 2] (Example 11) Except that the angular velocity of each of the rollers 4a and 4b is set to be nine times the transport speed of the belt-shaped substrate S,
A cylindrical nickel-metal hydride secondary battery was manufactured in the same manner as in Example 1.

(Example 12) A cylindrical nickel-metal hydride secondary battery is manufactured in the same manner as in Example 1, except that the angular speed of each of the rollers 4a and 4b is set to be 10 times the transport speed of the belt-shaped substrate S. did.

(Example 13) A cylindrical nickel-metal hydride secondary battery is manufactured in the same manner as in Example 1, except that the angular speed of each of the rollers 4a and 4b is set to be 50 times the transport speed of the belt-shaped substrate S. did.

(Example 14) A cylindrical nickel-metal hydride secondary battery is manufactured in the same manner as in Example 1, except that the angular velocity of each of the rollers 4a and 4b is set to be 100 times the transport speed of the belt-shaped substrate S. did.

With respect to the obtained secondary batteries of Examples 11 to 14, the filling rate of the positive electrode in the substrate was measured, and the results are shown in FIG. FIG. 5 also shows the results of Example 1 described above.

As apparent from FIG. 5, Examples 1, 11 to 1
In the secondary battery of No. 4, the paste filling rate of the positive electrode was 96% in order,
76%, 92%, 98% and 98%.

The secondary batteries of Examples 11 to 14 were
The discharge capacity was measured in the same manner as described above, and the results are shown in Table 3 below. Table 3 also shows the results of Example 1 described above.

[0065]

[Table 3]

[0066]

As described in detail above, according to the present invention, it is possible to provide a paste filling apparatus capable of improving the paste filling rate in a substrate.

Further, according to the present invention, it is possible to provide a method for manufacturing a high capacity, long life alkaline secondary battery including a positive electrode and / or a negative electrode having an improved paste filling rate in a substrate.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a paste filling device according to the present invention.

FIG. 2 is a partially cutaway perspective view showing an example of an alkaline secondary battery manufactured by the method according to the present invention.

FIG. 3 shows paste filling ratios of positive electrodes and arrangement states of rollers (an angle θ) of the nickel-hydrogen secondary batteries of Examples 1 to 4 and Comparative Example.
FIG. 3 is a characteristic diagram showing a relationship with the graph.

FIG. 4 is a characteristic diagram showing a relationship between a paste filling rate of a positive electrode of the nickel-metal hydride secondary batteries of Examples 5 to 10 and a roller arrangement state (distance X).

FIG. 5 is a characteristic diagram showing a relationship between a paste filling rate of a positive electrode of the nickel-hydrogen secondary batteries of Examples 1 and 11 to 14 and a ratio of a rotation speed of a roller to a substrate loading speed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Paste accommodation container, 2 ... Substrate insertion port, 3 ... Feeding roller, 4a, 4b ... Roller.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Takeyoshi Kubota 3-4-10 Minamishinagawa, Shinagawa-ku, Tokyo Toshiba Battery Corporation

Claims (5)

[Claims] 1. A container for accommodating a paste, a substrate insertion opening formed at a bottom of the container, and a plurality of rotatable rollers disposed in the container. A paste filling device, wherein the paste filling device is separated from the substrate insertion opening by a substrate inserted into the container, and is arranged such that an angle between a line connecting the centers and the substrate becomes an acute angle. . 2. The paste filling apparatus according to claim 1, wherein the at least two rollers are arranged so that a distance to the substrate is 0 to 5 mm. 3. The paste filling step for a positive electrode or a negative electrode, wherein the substrate passes between two rotatable rollers arranged in a container containing the paste, and a line connecting the centers of the rollers and the substrate. A method for manufacturing an alkaline secondary battery, wherein an angle between the substrate and the substrate is an acute angle. 4. The distance between each of the rollers and the substrate is zero.
The method for producing an alkaline secondary battery according to claim 3, wherein the thickness is from 5 to 5 mm. 5. The method according to claim 3, wherein a rotation speed of each of the rollers is higher than a passing speed of the substrate.