JPH09213361A - Manufacture of spiral plate group - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a spiral plate group capable of ensuring a capacity as designed by suppressing generation of a gap between a sheet-shaped separator and a reinforcing separator at the initial time of winding. SOLUTION: In the case of manufacturing a spiral plate group by winding after arranging a positive/negative plate 31, 32 in surfaces 33a, 33b respectively of a sheet-shaped separator 33, a reinforcing separator 34 is arranged in a part of the sheet-shaped separator where at least a winding start end part 31b of the positive plate 31 is positioned, and a part R1 arranging this reinforcing separator is formed in curved shape.

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 spirally wound electrode plate assembly incorporated in a cylindrical sealed battery, and more specifically, it suppresses damage to the electrode plate at an initial stage of winding the electrode plate. And a method of manufacturing a spirally wound electrode plate group having a design standard capacity.

[0002]

[Related technology] Nickel-hydrogen secondary battery and nickel-
An alkaline secondary battery such as a cadmium battery has a sealed structure as a whole, and its shape has a cylindrical shape and a prismatic shape. Here, for example, the structure of a cylindrical sealed nickel-hydrogen secondary battery will be described with reference to FIG.

A cylindrical nickel-hydrogen secondary battery includes a cylindrical bottomed outer can 1 for accommodating an electrode plate group 3, and an electrode plate group 3.
Is fitted into the opening 1a of the outer can 1 and then mounted,
A lid plate 2 for sealing the opening 1a is provided. The cylindrical bottomed outer can 1 is a cylindrical bottomed can made of steel plated with nickel, has an opening 1a having a circular shape in plan view, and also has an external terminal for the negative electrode. Also serves as.

The lid plate 2 is provided with a positive electrode terminal 21 in the center thereof and has a circular shape in plan view which fits the opening 1a of the outer can, and is connected to the positive electrode terminal at a predetermined position on the lower surface thereof. A positive electrode lead plate (not shown) is provided. As shown in FIG. 2, the electrode plate group 3 is electrically insulated between one sheet-shaped positive electrode plate (nickel electrode) 31 and one sheet-shaped negative electrode plate (hydrogen storage alloy electrode) 32. It has a structure in which a single sheet-shaped separator 33, which is liquid-storing and liquid-holding, is spirally wound in a state of being in contact with the sheet-shaped separator 33 in between. The electrode plate group 3 is inserted from the opening 1 a of the outer can and accommodated in the outer can 1. Therefore, the electrode plate group 3
Is formed into a cylindrical shape so as to fit the inner shape of the outer can 1 as a whole.

As the positive electrode plate (nickel electrode) 31, for example, a porous conductive base material such as a sponge-like nickel sheet is filled and coated with an active material mixture mainly composed of nickel hydroxide that operates as a positive electrode active material. Things are usually used. Examples of the negative electrode plate (hydrogen storage alloy electrode) 32 include a porous conductive base material such as a punched nickel sheet or a nickel net, a conductive material powder such as hydrogen storage alloy powder and nickel powder, and polyvinylidene fluoride. A material obtained by applying a mixture obtained by mixing the above-mentioned binder powder with a predetermined ratio is usually used.

As the sheet-like separator 33, for example, a sheet made of porous synthetic resin is usually used. As an example of the procedure for assembling the electrode plate group 3, as shown in FIG. 3, first, the positive electrode plate 31 is attached to one surface 33a of the sheet-like separator 33 and the negative electrode plate 32 is attached to the other surface 33b in a surface contact state. And the electrode plate group precursor 30 is formed. At this time, the end portion 31 a of the positive electrode plate 31 and the negative electrode plate 32
And the end portions 32a of the sheet-shaped separator 33 are arranged along the longitudinal direction of the sheet-shaped separator 33 with a predetermined space therebetween.

After that, the substantially central portion of the space 33d is sandwiched between the cracks 41 of the rotary shaft (hereinafter referred to as split shaft) 4 having the cracks 41 formed along the axial direction. Next, the split shaft 4 is rotated in the direction of arrow Q about its axis. That is, it is wound so that the negative electrode plate 32 is located outside. In this way, when the split shaft 4 is rotated, the winding work proceeds in the order of (a), (b), (c), and (d) of FIG. 4, and together with the sheet-shaped separator 33, the positive electrode plate 31. And the negative electrode plate 32 are rolled up. In this way, the electrode plate group precursor 30 is wound in a spiral shape, and the positive electrode plate 31 and the negative electrode plate 32 have the sheet-like separator 33 interposed between them. Is manufactured. In the present invention, the split shaft 4
A portion which is sandwiched between the cracks 41 and serves as a central axis during the winding operation is referred to as a winding start point 33c.

By the way, when the electrode plate precursor 30 is wound, at the initial winding stage as shown in FIG. 4, since the radius of curvature at the time of winding is small, the curvature of the outer circumference is high.
Therefore, a large load may be applied to the sheet-shaped separator 33 in the initial stage of winding, and the sheet-shaped separator 33 may be damaged. Particularly, at the winding start end portion 31b of the positive electrode plate 31 shown in FIG. 4A, a large stress concentrates at the beginning of the winding, so that the sheet separator 33 is easily damaged (FIG. 4).
(C)).

Here, the portion 3 of the sheet-like separator 33
If damage occurs in 3e, the sheet-like separator 33
Therefore, the electric insulating property may be broken, the positive electrode plate 31 may come into contact with the adjacent negative electrode plate 32, and a short-circuit accident may occur. Therefore, when the spiral electrode plate group 3 is manufactured, in order to prevent the occurrence of the above-mentioned short circuit accident, as shown in FIG. 5, the winding start end of the positive electrode plate 31 in the sheet-like separator 33 is prevented. The reinforcing separator 34 is disposed at the portion 33e where the portion 31b is located, and the separator has a double structure. That is, the separator is reinforced by doubling the separator in the portion to which the load is applied, and the separator is prevented from being damaged due to winding. Here, in the present invention, a portion where the reinforcing separator is disposed on the sheet-like separator is referred to as a reinforcing separator disposing portion R.

Here, as a method of disposing the reinforcing separator on the sheet-shaped separator, a method of welding the reinforcing separator 34 to one surface of the sheet-shaped separator 33 by an ultrasonic welding machine is usually adopted. At this time, as the reinforcing separator 34, for example, a rectangular sheet made of the same material as that of the sheet-like separator 33 as shown in FIG. 5 is used. A dimension H in the width direction (direction along arrow J in the figure) of the reinforcing separator 34 is substantially the same as the width of the sheet-like separator 33, while the dimension H of the sheet-like separator is orthogonal to the width direction. The dimension L in the direction along the longitudinal direction may be arbitrarily set so as to cover the range to be reinforced.

As shown in FIG. 5, the reinforcing separator 34 is superposed on a predetermined position of the sheet-shaped separator 33, and then the side portion of the sheet-shaped separator 33 which is orthogonal to the longitudinal direction is usually welded. . As the procedure of this welding, for example, as shown in FIG. 6, the sheet-shaped separator 33 and the reinforcing separator 34 are superposed, and these are placed on the lower table 51 having the flat surface 51a, and the welding points 34a, 34a are placed. Ultrasonic welding is performed in a state in which the ultrasonic horn 52 of the ultrasonic welding machine having the contact surfaces 52a and 52a matching with is pressed against the welding location. Therefore, at this point of time, the sheet-like separator 33 and the reinforcing separator 34 are in a flat surface-contact state.

As described above, the electrode plate group precursor employing the sheet-shaped separator having the reinforcing separator arranging portion R is (a), (b),
It is wound in the order of (c) and (d). In this case, since the reinforcing separator 34 is located at the portion 33e of the sheet-shaped separator 33 corresponding to the winding start end 31b of the positive electrode plate 31, the portion 33e is reinforced,
Damage at the beginning of winding is suppressed, and thus the occurrence of short circuit accidents is suppressed.

[0013]

By the way, the sheet-like separator and the reinforcing separator are provided at two welding points 3
4a and 34a are welded and the other portions are not welded but are simply in surface contact. In other words, the reinforcing separator 34 is flat at both end portions (welding points 34
Only a, 34a) are fixed to the sheet-like separator 33. When the spiral electrode plate group is manufactured using the sheet-like separator 33 in such a state, as shown in FIG. A compressive force acts in the direction along the inner circumference of the wound separator, as indicated by P and P. Then, when the compressive force becomes large, the reinforcing separator 34 is deformed, and the welding spot 34
A part other than a and 34a may be wrinkled and separated from the sheet-like separator 33.

As described above, when the reinforcing separator 34 and the sheet-shaped separator 33 are separated from each other, a gap V is generated between them, and as a result, the distance between the positive electrode plate and the negative electrode plate (hereinafter referred to as the positive-negative electrode distance). ) Spreads, the electrode reaction is hindered in the obtained electrode plate group, and it may be difficult to secure a target capacity. When a battery is manufactured by incorporating such an electrode plate group, the obtained battery does not exhibit desired characteristics and the characteristics become unstable.

The present invention solves the above-mentioned problems in the manufacture of a conventional spirally wound electrode plate group, suppresses the formation of voids between the sheet-like separator and the reinforcing separator at the beginning of winding, and is designed as designed. It is an object of the present invention to provide a method for manufacturing a spiral electrode plate group that can secure the capacity.

[0016]

In order to achieve the above object, according to the present invention, when a positive electrode plate and a negative electrode plate are arranged on respective surfaces of a sheet-like separator and then wound, a spiral electrode plate group is manufactured. A spiral pole, wherein a reinforcing separator is disposed at a location of the sheet-shaped separator where at least the winding start end of the positive electrode plate is located, and the location of the reinforcing separator is curved. A method for manufacturing a plate group is provided.

In the method for manufacturing a spiral electrode plate group according to the present invention, the sheet-shaped separator may be used in the form of a single leaf at the time of the winding, or it may be folded in two and the fold portion thereof may be the above-mentioned. It may be used as a winding start point. In the method for manufacturing a spiral electrode plate group according to the present invention, since the place where the reinforcing separator is arranged is curved in advance, the electrode plate group precursor is wound with a high curvature in the winding operation performed in the subsequent stage. In addition, the compressive force applied to the reinforcing separator in the direction along the peripheral surface of the wound separator is reduced, and deformation of the reinforcing separator is suppressed. for that reason,
Generation of voids between the sheet-shaped separator and the reinforcing separator is suppressed.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION First, a case where a sheet-shaped separator is used in a single leaf shape at the time of winding will be described. In this case, first, a step of arranging the reinforcing separator at a predetermined position of one sheet-like separator, and forming the reinforcing separator arranging portion into a curved shape (hereinafter referred to as step A), A step of producing a positive electrode plate group precursor by arranging a positive electrode plate on one surface of the sheet-like separator obtained in A and a negative electrode plate on the other surface thereof in a surface contact state (hereinafter referred to as step B); And a step of producing a spiral electrode plate assembly by winding the electrode plate assembly precursor (hereinafter referred to as step C).

In the present invention, the steps A, B, and C described above are sequentially performed, so that in the winding operation (initial winding), the reinforcing separator is provided with the inner periphery of the wound separator. It is possible to reduce the compressive force that acts in the direction along which the deformation of the reinforcing separator is suppressed. As a result, it is possible to suppress the formation of voids between the sheet-shaped separator and the reinforcing separator, and to obtain a spiral electrode plate group having a target capacity.

First, in step A, a sheet-shaped separator made of an electrically insulating resin is prepared. The sheet-shaped separator is not particularly limited as long as it is conventionally used, and for example, a nylon sheet or the like is used. Further, a strip-shaped separator made of an electrically insulating resin is prepared as a reinforcing separator similar to the sheet-shaped separator.

The size of this reinforcing separator 34 is shown in FIG.
In the same manner as the case shown in, the widthwise dimension H is set to be substantially the same as the width of the sheet-like separator 33, and the dimension L in the longitudinal direction of the sheet-like separator is set so as to cover the range to be reinforced. It is set arbitrarily. Next, the reinforcing separator is disposed on the prepared sheet-shaped separator, and the reinforcing separator disposing portion is curved.

Here, an example of a method of disposing the reinforcing separator in a curved shape on the sheet-shaped separator will be described below.
That is, first, the reinforcing separator is superposed on a predetermined position on one surface of the sheet-shaped separator. And in FIG.
As shown in FIG.
Then, the overlapping portion r is placed and the overlapping portion r is curved. After that, the ultrasonic horn 54 having the contact surfaces 54a, 54a matching the curved surface of the lower base 53 is attached to the welding point 3
Ultrasonic welding is performed while being pressed against 4a and 34a.
In this way, the sheet-shaped separator 33 and the reinforcing separator 34 are curved in a predetermined position 34a, 3
4a is welded to form a sheet-like separator 33 having a curved reinforcing-plate-separating portion R ₁ as shown in FIG. Here, the contact surface 5 of the lower base 53
By arbitrarily setting the radius of curvature of 3a, the curvature of the reinforcing separator arranging portion R ₁ can be set to a desired value. At this time, if the curvature is set to a value close to the curvature of the outer periphery of the electrode plate group in the initial winding stage during the winding operation performed in the latter stage, the reinforcing separator is aligned with the inner peripheral surface of the wound separator. This is preferable because the compressive force acting in the vertical direction can be reduced.

After the above step A is completed, in step B, first, the positive electrode plate (nickel electrode) obtained by the conventional method is first prepared.
31 and a negative electrode plate (hydrogen storage alloy electrode) 32 are prepared, and then, as shown in FIG. 11, the positive electrode plate 31 is provided on one surface 33a of the sheet-like separator 33 obtained in step A,
The negative electrode plate 32 is arranged on the other surface 33b in a surface contact state to manufacture the electrode plate group precursor 30A.

At this time, the respective electrode plates have their end portions 31
a and 32a are arranged at a predetermined interval along the longitudinal direction of the sheet-like separator, and the positive electrode plate 31 is
The winding start end portion 31b is arranged so as to overlap with the reinforcing separator arrangement portion R ₁ . In this manner, the electrode plate group precursor 30A in which the positive electrode plate 31 and the negative electrode plate 32 are arranged on the sheet-shaped separator having the curved reinforcing separator disposing portion R ₁ at a predetermined position is formed ( Figure 1
1).

Next, it is transferred to step C, where the electrode plate precursor 30A obtained in step B is wound to produce the spiral electrode plate group 3. This winding work is performed by the electrode plate group precursor 30A.
The starting point 33c of winding is approximately the center of the space 33d formed between the end 31a of the positive electrode plate and the end 32a of the negative electrode.
It is carried out by sandwiching the split shaft 4 in the split 41 of the split shaft 4 and rotating the split shaft 4 in the Q direction. That is, the electrode plate group precursor 30A is wound so that the negative electrode plate 32 is located outside.

By the winding operation as described above, the spiral electrode plate group 3 in which the sheet-shaped separator 33 is interposed between the positive electrode plate 31 and the negative electrode plate 32 as shown in FIG. 2 is manufactured. . At this time, in the electrode plate precursor 30A, since the reinforcing separator disposing portion R ₁ having a curved shape is formed in advance, the reinforcing separator 34 is wound around the reinforcing separator 34 even in the initial winding stage where the curvature is large. The compressive force acting in the direction along the inner peripheral surface of the separated separator is suppressed, and the reinforcing separator 34 is unlikely to deform. As a result, it becomes difficult for the sheet-shaped separator 33 and the reinforcing separator 34 to separate from each other at the reinforcing separator arranging portion R ₁ , and a void be formed between these separators. Therefore,
The expansion of the distance between the positive and negative electrodes is suppressed.

As described above, the process A, the process B, and the process C
After the above, the obtained spiral electrode plate group is housed in a cylindrical bottomed outer can together with the alkaline electrolyte, and a cylindrical nickel-hydrogen secondary battery is manufactured. Next, a case where the sheet separator is folded in two will be described. In this case,
For example, as shown in FIG. 12, the precursor is folded in two, and the winding work is performed with the fold portion as the winding start point 33c. Also in this case, the winding start end of the positive electrode plate is
Since it is reinforced by the reinforcing separator 34 and has a curved shape, the same effect as described above can be achieved.

[0028]

【Example】

Example 1 A sheet-shaped separator made of nylon having a width of 45 mm and a thickness of 0.2 mm, and a strip-shaped reinforcing separator made of nylon having a width of 45 mm, a dimension in the direction orthogonal to the width direction of 20 mm, and a thickness of 0.1 mm. Prepared. Then, as shown in FIG. 9, a sheet-like separator 33 and a reinforcing separator 34.
Abutting surface 5 with a radius of curvature of 5 mm
It was placed on the lower table 53 having 3a. Then, with the ultrasonic horn 54 having a predetermined contact surface 54a being pressed against the overlapping portion r, the welding portions 34a, 34a.
Was ultrasonically welded. In this way, a sheet-shaped separator having a curved reinforcing-separator disposing portion R ₁ as shown in FIG. 10 was manufactured.

Next, a positive electrode plate (nickel electrode) having a length of 42 mm, a width of 70 mm and a thickness of 0.6 mm was manufactured according to a conventional method, and a length of 42 mm, a width of 100 mm and a thickness of 0.4 m.
m negative electrode plate (hydrogen storage alloy electrode) was manufactured according to a conventional method. Then, as shown in FIG. 11, the obtained positive electrode plate 3
1 so that the winding start end portion 31b covers the reinforcing separator disposing location R _1.
3 was abutted on one surface 33a. Further, on the other surface 33b of the sheet-shaped separator, the negative electrode is arranged so that the end 32a is located at a position 20 mm away from the end 31a of the positive electrode plate in the longitudinal direction of the sheet-shaped separator 33 in the right direction in FIG. The plate 32 was abutted. Thus, the electrode plate group precursor 30A was formed.

Next, in the obtained electrode plate group precursor 30A, as shown in FIG. 11, a substantially central portion of a space 33d opened between the end portion 31a of the positive electrode plate and the end portion 32a of the negative electrode plate. By sandwiching the split shaft 4 and rotating the split shaft 4 in the direction of arrow Q, the electrode plate group precursor 30A was spirally wound. Then, a spiral electrode plate group having a cylindrical shape having a diameter of 13 mm and a height of 45 mm was manufactured.

Next, nickel-plated thickness 0.3
A cylindrical bottomed outer can having a circular opening with an inner diameter of 13.3 mm and a vertical dimension of 50 mm was prepared. Then, the electrode plate group 3 was inserted into the inside through the opening of the outer can, and subsequently, as an electrolytic solution, K
2 cc of alkaline aqueous solution containing OH as a main component was injected into the outer can.

Next, the positive electrode lead plate attached to the insulator-equipped lid plate having the positive electrode terminal at the center and having the outer diameter of 13.3 mm and the thickness of 3 mm is welded to the other end of the positive electrode tab, After electrically connecting the positive electrode plate and the positive electrode terminal, the lid plate was fitted and mounted in the opening of the outer can. The negative electrode tab was connected to an outer can that also functions as a negative electrode terminal. afterwards,
The fitting portion is caulked to obtain a rated capacity of 1200
10000 mAh cylindrical nickel-hydrogen secondary batteries were manufactured.

These batteries were subjected to initial activation treatment by charging and discharging twice at 1 C at a temperature of 20 ° C., then charged at 160% at 0.1 C at a temperature of 20 ° C. and then at a temperature of 20 ° C. At 1 C, discharge was performed and the discharge capacity at that time was measured. Regarding the measured values of the discharge capacities of the obtained batteries, Table 1 shows the average value, maximum value, minimum value, (maximum value)-(minimum value) of all the batteries.

After the discharge capacity was measured, all the batteries were disassembled, the state of the spiral electrode plate group was observed, and it was examined whether or not voids were formed at the reinforcing separator disposing place R ₁ . Then, the number of batteries with voids was counted, the ratio of the number of batteries with voids to all the batteries was obtained, and this ratio is also shown in Table 1 as the void generation rate (%). Comparative Example 1 For comparison with the battery of Example 1, as shown in FIGS. 5 and 6, a sheet-like separator 33 and a reinforcing separator 3 were used.
4 was ultrasonically welded in a flat state, that is, except that the overlapped portions were not curved.
In the same manner as in Example 1, 10000 cylindrical nickel-hydrogen secondary batteries having a rated capacity of 1200 mAh were manufactured. Then, in the same manner as in Example 1, the average value, maximum value, minimum value, (maximum value)-(minimum value), and void generation rate of the obtained battery were obtained, and the results are also shown in Table 1. did.

[0035]

[Table 1]

As is clear from the results in Table 1, Example 1
Battery has an average discharge capacity of 1195 mAh,
It shows almost the same value as the rated capacity. Further, the difference between the maximum value and the minimum value of the discharge capacity is small, and the variation among the batteries is small. That is, the battery of Example 1 can secure the characteristics as designed, and the characteristics are stable. Also,
The void generation rate was also 0%, and voids did not occur at the place where the reinforcing separator of the spiral electrode plate group was arranged.

As described above, when the method for producing a spiral electrode plate group according to the present invention is adopted, in the obtained electrode plate group, the generation of voids is remarkably suppressed, so that the capacity as designed can be secured. On the other hand, the battery of Comparative Example 1 has a lower average discharge capacity and larger variations than the battery of the present invention. In addition, the generation rate of voids is also high.

This is because the electrode plate group incorporated in the battery of Comparative Example 1 had voids at the locations where the reinforcing separators were arranged, and the distance between the positive and negative electrodes was widened, so that the electrode reaction was hindered. It is thought that this is because the desired capacity of the battery could not be secured and the characteristics became unstable.

[0039]

As is apparent from the above description, in the method for manufacturing a spiral electrode plate group of the present invention, the reinforcing separator disposing portion formed by disposing the reinforcing separator on the sheet separator is wound. Since it is preformed into a curved shape close to the rotated state, when winding the electrode plate group precursor in a spiral shape,
The compressive force applied in the direction along the peripheral surface of the wound separator is reduced, and deformation of the reinforcing separator due to the compressive force is suppressed. Therefore, it is possible to suppress the formation of voids between the sheet-shaped separator and the reinforcing separator, and the distance between the positive and negative electrodes can be brought close to each other as designed, so that the spiral electrode plate group obtained by the present invention is good. The electrode reaction can proceed in such a state, and the target capacity can be secured. Therefore, when the method for manufacturing a spiral electrode plate group according to the present invention is adopted, it is possible to obtain a non-defective battery whose characteristics are as designed and is stable, and the non-defective rate in battery manufacturing is improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of a cylindrical sealed battery.

FIG. 2 is a top plan view showing the configuration of a spiral electrode plate group.

FIG. 3 is a perspective view showing a structure of an electrode plate group precursor.

FIG. 4 is a view on arrow A in FIG. 3, showing a winding procedure of the electrode plate group precursor.

FIG. 5 is a perspective view of a portion where a reinforcing separator is provided.

FIG. 6 is a side view showing a welding procedure of the sheet separator and the reinforcing separator.

FIG. 7 is a configuration diagram showing a winding procedure of an electrode plate group precursor having a reinforcing separator disposed portion.

FIG. 8 is a plan view showing the vicinity of the center of a spiral electrode plate group.

FIG. 9 is a side view showing a procedure for welding the sheet separator and the reinforcing separator in the present invention.

FIG. 10 is a perspective view of a portion where a reinforcing separator is arranged in the present invention.

FIG. 11 is a perspective view showing a structure of an electrode plate group precursor in the present invention.

FIG. 12 is a schematic configuration diagram of an electrode plate group precursor according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Cylindrical bottomed outer can 1a Opening 2 Lid plate 21 Positive electrode terminal 3 Spiral electrode plate group 30 Electrode plate group precursor (conventional) 30A Electrode plate group precursor (in the present invention) 31 Positive electrode plate 32 Negative electrode plate 33 Sheet-shaped separator 34 Reinforcing separator 4 Split shaft 51 Lower stand 52 Ultrasonic horn 53 Lower stand (in the present invention) 54 Ultrasonic horn (in the present invention) R Reinforcing separator disposing location (flat) R ₁ Reinforcing separator Location (in the present invention)

Claims (1)

[Claims] 1. When a positive electrode plate and a negative electrode plate are arranged on each surface of a sheet-shaped separator and then wound to manufacture a spiral electrode plate group, at least the winding start end portion of the positive electrode plate is located in the sheet-shaped separator. A method of manufacturing a spiral electrode plate group, characterized in that a reinforcing separator is disposed at the location, and the location at which the reinforcing separator is disposed is curved.