JP2002110171A - Conductive core for electrode plate of battery and battery using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive core for an electrode plate of the battery which ensure a filled density of an active material and allow efficiently manufacturing a spiral electrode, and provide a high capacity battery. SOLUTION: A strip conductive core 10 is used in the spiral electrode and provides a number of holes. An open area ratio, which is an occupied ratio by the holes on a surface of the core in a region 10a, which is the beginning of winding, is smaller than the one in a region 10b, which is all the region except the region 10a so that a tension strength of the region 10a in the winding direction is greater than the one of the region 10b in the winding direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery having a power generating element in which a spiral electrode body is impregnated with an electrolytic solution, and a conductive core used for the battery electrode plate.

[0002]

2. Description of the Related Art At present, alkaline storage batteries such as nickel-cadmium storage batteries and nickel-hydrogen storage batteries are used in various devices including portable devices.
The structure of the alkaline storage battery is such that a spirally wound electrode body formed by winding a positive electrode plate and a negative electrode plate through a separator such as an organic fiber non-woven fabric is impregnated with an alkaline electrolyte and then stored in an outer can. The one whose opening is sealed with a sealing lid is typical. Here, the spiral electrode body is generally manufactured by winding a positive electrode plate and a negative electrode plate while winding a separator using a core, which is formed of a split pin or a pair of pins.

The positive electrode plate and the negative electrode plate are both of a sintered type and a non-sintered type, and are manufactured by filling a conductive core with an active material in either system. As the conductive core, there is widely used a strip-shaped plate made of a nickel plate or a nickel-plated steel plate, in which a plurality of holes are formed to increase the packing density of the active material (punched metal). In particular, in the case of a sintered type, this type of conductive core is mainly used.

[0004] By the way, as is generally the case with batteries, there is a high demand for such an alkaline storage battery to have a high capacity. Therefore, it is necessary to increase the packing density of the active material also in the above-mentioned electrode plate, and in the conductive core used for the electrode plate, the diameter of the hole is increased or the interval between the holes is reduced. Accordingly, the aperture ratio is set to be as large as possible, and the plate thickness is set to be as thin as possible (the smaller the plate thickness, the more the number of turns of the electrode plate can be increased).

[0005]

However, when the thickness of the conductive core is reduced and the porosity is increased, the tensile strength of the conductive core is reduced. Tends to occur. That is, an electrode plate using a conductive core body having a small thickness and a large porosity is easily stretched in the winding direction due to tension between the core and the core when the spiral electrode body is manufactured. Then, when the electrode plate is elongated, the outer diameter of the spiral electrode body becomes large, so that the accommodating property in the outer can becomes worse,
In some cases, there is a problem that the yield in manufacturing the spiral electrode body is deteriorated due to the occurrence of the winding deviation.

[0006] In view of the above problems, the present invention provides a conductive core for a battery electrode plate capable of producing a spiral electrode body with a high yield while maintaining a high packing density of an active material. It is another object of the present invention to produce a high-capacity battery with a high yield.

[0007]

According to the present invention, in order to achieve the above object, the configuration of a strip-shaped conductive core having a plurality of holes formed therein for use in a spiral electrode body is defined as a winding start portion, that is, a winding. The tensile strength of a predetermined length portion from the start end was set to be higher than the tensile strength of the portion excluding the winding start portion.

Here, in the conductive core body, as a method for increasing the tensile strength of the winding start portion, the opening ratio, which is the ratio of the hole on the core surface at the winding start portion, is determined by changing the opening ratio. And a method in which the plate thickness of the winding start portion is made larger than the plate thickness of the portion excluding the winding start portion. At the time of winding the spiral electrode body, a relatively strong tensile force is applied to the region of the winding start portion of the conductive core because the winding curvature is small. Since the tensile strength of the portion is increased, its elongation is suppressed.

On the other hand, in the region except for the winding start portion,
Although the tensile strength is relatively low, the tensile force applied in this region is relatively weak, so that the elongation is also suppressed. Since the tensile strength may be low in this region, a large filling rate of the active material can be secured by setting the porosity large. Therefore, the battery electrode plate using the conductive core of the present invention has an effect that the filling density of the active material is ensured and the elongation during winding is small.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the structure of a battery provided with a spiral electrode body and the manufacture of the spiral electrode body will be described. FIG. 5 is a perspective view (partial cross section) of the alkaline storage battery according to the present embodiment, in which a positive electrode plate 1 and a negative electrode plate 2 are spirally wound with a separator 3 interposed therebetween.
Is impregnated with an alkaline electrolyte (not shown) and accommodated in a cylindrical outer can 5. The opening of the outer can 5
It is sealed with a sealing lid 6.

As the positive electrode plate 1, either a sintered type or a non-sintered type in which an active material paste is applied to a substrate may be used, but nickel hydroxide as an active material is held on the substrate. An electrode plate, wherein a conductive core body (punched metal) having a plurality of holes formed in a conductive strip-shaped plate is used as the electrode plate. As the negative electrode plate 2, similarly to the positive electrode plate 1, any of a sintered type and a non-sintered type may be used. However, the negative electrode plate 2 is an electrode plate holding cadmium hydroxide as an active material,
A conductive core (punched metal) having a plurality of holes formed in a conductive strip-shaped plate is used as the electrode plate.

As the separator 3, a film separator material can be used in addition to the nonwoven fabric conventionally used for the separator. Next, FIG. 4 is a perspective view illustrating a winding step of manufacturing a spiral electrode body. In this drawing, reference numeral 100 denotes a roll around which a separator material is wound, and reference numeral 50 denotes a core.

As shown by an arrow A in FIG. 4 (a), the separator 3 has a winding core 50 fitted at the winding start position and is sandwiched. Then, the winding of the separator 3 is performed as shown in FIG.
This is performed by rotating the core 50 in the direction indicated by the arrow B in FIG. At this time, the separator 3 is unwound from the roll 100 in accordance with the rotation, and tension is applied between the roll 100 and the core 50, and tension is also applied between the end 3 a of the separator 3 and the core 50. It is performed while adding.

The positive electrode plate 1 and the negative electrode plate 2 are wound around the separator 3 by inserting the winding start portion 1a of the positive electrode plate 1 and the winding start portion 2a of the negative electrode plate 2 into the portion where the separator is wound. It is sandwiched between and wound up. Then, after the winding of the positive electrode plate 1 and the negative electrode plate 2 is completed, the spiral electrode body is completed by cutting the winding end end of the separator 3 and extracting the winding core 50.

By repeating the above steps, the spiral electrode body is continuously manufactured. In the alkaline storage battery, the spirally wound electrode body 4 manufactured as described above is housed in an outer can 5, and the spirally wound electrode body 4 is impregnated with the alkaline electrolyte by injecting the alkaline electrolyte into the spirally wound electrode body 4. 5 is manufactured through the step of closing the lid 5 with the lid 6.

Next, the details of the conductive core used for the positive electrode plate 1 and the negative electrode plate 2 will be described in Embodiments 1 and 2. Embodiment 1 FIG. 1 is a perspective view of a conductive core 10 used for a positive electrode plate 1 and a negative electrode plate 2 of the present embodiment.

As shown in FIG. 1, the conductive core 10 has a rectangular plate made of a conductive plate material (a nickel plate or a nickel-plated stainless steel plate). It is opened at a constant pitch in the length direction, but a fixed length X from the end 10e on the winding start side.
The diameter of the hole 200a in the region 10a of the
The diameter of the hole 200b at 0b is set to be smaller than that of the hole 200b, whereby the opening ratio (total area of holes included per unit area of the conductive core) is reduced.

In the present embodiment, the opening ratio is changed by changing the hole diameter with the same hole pitch in the region 10a and the region 10b. However, the opening ratio may be changed by changing the hole pitch. It is possible. Thus, the region 10a and the region 10
The conductive core body 10 in which the opening ratio is changed in b can be manufactured by punching a conventionally used strip-shaped plate with a punch, but the diameter of the punch used in the regions 10a and 10b is changed. There is a need.

The conductive core 10 having the above-described porosity.
Has the following advantages as compared with the conventional case where the porosity is uniform in the entire area of the conductive core. That is, when the spirally wound electrode body is wound on the conductive core 10, a relatively strong tensile force is applied in the region 10a and a relatively weak tensile force is applied in the region 10b.

Here, in the conductive core 10, the winding start portion 1
0a, the aperture ratio is set small, so that the conductive core 10
Has a large true cross-sectional area when it is cut in the width direction, so that the tensile strength of this region 10a is increased. Therefore, in the portion 10b excluding the winding start portion, even if the tensile strength is not so high, the elongation of the conductive core 10 is suppressed, and accordingly, the fall of the active material due to the elongation of the conductive core is suppressed.

On the other hand, the filling rate of the active material in the portion 10b excluding the winding start portion can be ensured to be large because the porosity of the region 10b is set relatively large. Therefore,
In the above conductive core, while ensuring the filling rate of the active material,
Elongation during winding can be suppressed. On the other hand, a conductive core having a uniform opening ratio in the entire region, for example, a conductive core in which the opening ratio of the entire conductive core 10 is set to be equal to the opening ratio of the winding start portion 10a In this case, the elongation of the conductive core is suppressed, but the filling rate of the active material is reduced, or when the opening rate of the portion 10b excluding the winding start portion is set to be equal to,
Although the filling rate of the active material can be ensured, the elongation of the conductive core cannot be suppressed.

In order to obtain such an effect, the winding start portion 1
The length X of 0a is about the outer circumference of the core 50 (10 m
m) or more, and if it is more than 20 mm from the end of the winding start, there is not much tensile force at the time of winding, and in order to increase the active material filling amount, the area 1
Since it is better to make 0a smaller, it is preferable to set it to 20 mm or less.

The porosity in the region 10a, the region 1
The opening ratio at 0b is desirably set as large as possible within a range where the tensile force applied at the time of winding is cut off. (Generally, the ratio of the porosity of the region 10a to the porosity of the region 10b is desirably 0.50 to 0.75.) (Embodiment 2) In this embodiment, the positive electrode plate 1 and the negative electrode plate 2 It is the same as Embodiment 1 except that the conductive core used is different.

That is, in the conductive core of the first embodiment, the opening ratio at the winding start portion 10a is set to be smaller than the opening ratio at the portion 10b excluding the winding start portion. Although the tensile strength of the core body was increased, the conductive core body of the present embodiment requires that the thickness of the core body at the beginning of winding be thicker than the thickness of the core except for the beginning of winding. Thus, the tensile strength of the conductive core is increased.

Specifically, as shown in FIG. 3, such a conductive core has a similar opening pattern only in a region 20a of the conductive core 21 having a uniform opening ratio. It can be realized by joining the conductive core pieces 22 held by welding or the like. As in the case of the conductive core 10 of the first embodiment, the tensile strength of the conductive core is higher in the region 20a than in the region 20b. In this conductive core, the porosity is the same in the region 20a and the region 20b.
The point that the packing density of the active material in the region 20a is smaller than the packing density of the active material in the region 20b is similar to the conductive core of the first embodiment because the plate thickness of 0a is large.

Therefore, the above-mentioned conductive core can be used in the first embodiment.
Has the same superiority as the conductive core 10 of the first embodiment. Example FIG. 2 is a view for explaining an opening pattern in a conductive core according to the present example.

As shown in FIG. 2, the diameter of the holes formed in the conductive core is indicated by r, the pitch of the holes in the longitudinal direction is indicated by 2h, and the pitch of the holes in the width direction is indicated by 1. In the hole pattern shown in FIG. 2, holes are formed at the same pitch in the longitudinal direction and at the same pitch in the width direction, but holes adjacent in the width direction are shifted by a half pitch (h). In the case of this opening pattern, the opening ratio of the conductive core is represented by πr ² / 8hl.

In the following examples and comparative examples, a strip-shaped plate made of nickel-plated stainless steel and having a thickness of 70 μm was used, and the pitch of the holes was common (h = 1.
2 mm, l = 3.6 mm). And Example 1,
In No. 2, the length X of the winding start portion is changed and the hole diameter r is changed.
Was changed with respect to the portion excluding the winding start part, thereby adjusting the opening ratio. In Example 3, the thickness of the winding start portion was changed with respect to the portion excluding the winding start portion.

Example 1 <Manufacture of Electrode Plate> In this example, the winding start end 10e in FIG.
In the winding start portion 10a between X = 10 mm in the longitudinal direction from the opening, a hole 200a is opened with a hole diameter r = 1.0 mm, and
In the part 10b excluding the winding start part, the hole diameter r = 1.5 m
m, a conductive core having a hole 200b was manufactured.

Next, a nickel powder was sintered on the conductive core by a continuous sintering method (slurry method) to produce a sintered nickel substrate. The thickness of the sintered nickel substrate was 0.60 mm for both the positive electrode plate and the negative electrode plate. Next, a positive electrode plate and a negative electrode plate were manufactured using the sintered nickel substrate. The positive electrode plate was manufactured by repeating the operation of immersing the sintered nickel substrate in an impregnating liquid containing nickel nitrate as a main component and performing an alkali treatment several times. The negative electrode plate was manufactured by repeating the operation of immersing the sintered nickel substrate in an impregnation liquid containing cadmium nitrate as a main component and performing an alkali treatment several times. Regarding the size of each electrode plate, the positive electrode plate had a length of 200 mm and a width of 35 mm, and the negative electrode plate had a length of 260 mm and a width of 35 mm.

<Manufacture of Battery> The method described in the embodiment of the present invention using the positive electrode plate and the negative electrode plate,
SC size alkaline storage battery a1 (1700 m nominal capacity)
Ah). (Example 2) <Manufacture of Electrode Plate and Battery> In FIG. 1, in the winding start portion 10a between X = 20 mm in the longitudinal direction from the winding start end 10e,
A conductive core having a hole 200a with a hole diameter r = 1.0 mm and a hole 200b with a hole diameter r = 1.5 mm was manufactured in a portion 10b other than the winding start portion. An SC-size alkaline storage battery a2 was manufactured in the same manner as in Example 1 except that this conductive core was used.

(Embodiment 3) In FIG. 3, a plate 7 having a hole 200 having a uniform hole diameter (r = 1.5 mm) in all regions is provided.
A conductive core 21 of 0 μm was manufactured. Next, the length X = 10 in the longitudinal direction from the winding start end 20e of the conductive core 21.
mm, has the same pattern as the conductive core 21 on the winding start portion 20a, and has a length of 10 mm, a width of 35 mm, and a thickness of 2 mm.
The conductive core pieces 22 of 0 μm were overlapped and welded to produce a conductive core. An SC-size alkaline storage battery a3 was manufactured in the same manner as in Example 1, except that the conductive core was used.

(Conventional Example 1) <Manufacture of Electrode Plate and Battery> In FIG. 6, a conductive core having a pattern in which the hole diameter is uniform (r = 1.5 mm) in all regions is used. In the same manner as in the above, an SC-size alkaline storage battery b1 was manufactured.

(Conventional Example 2) <Manufacture of Electrode Plate and Battery> In FIG. 6, except that the above-mentioned conductive core having a pattern in which the hole diameter is uniform (r = 1.0 mm) in all regions is used. As in the case of No. 1, an SC-size alkaline storage battery b2 was manufactured.

With respect to the alkaline storage batteries a1, a2, a3, b1, and b2 manufactured as described above, two items, the internal short-circuit rate and the battery capacity, of each battery were evaluated. (Evaluation 1) Internal short-circuit rate of battery A number of batteries were manufactured based on the above embodiment and the conventional example.
The ratio of short-circuited batteries to the total number of batteries (short-circuit rate inside batteries) was measured. Table 1 shows the measurement results of the internal short ratio.

[0036]

[Table 1] (Evaluation 2) Capacity of Battery The capacity of each battery manufactured based on the above Examples and Conventional Examples was measured as follows.

At a charging current of 0.1 C (0.17 A), 16
The battery was charged for 1 hour and then discharged at 1 C (1.7 A) until the discharge termination voltage reached 1.0 V, and the capacity at the time of discharging was measured.

[0038]

[Table 2] From Table 1, it can be seen that the alkaline storage batteries b1, b
It can be seen that the internal short-circuit rate is significantly reduced as compared with 2. When the cause of the battery in which the internal short-circuit occurred was examined, it was determined that the main causes were the penetration of the separator due to the breakage of the electrode plate at the beginning of winding, and the contact between the positive electrode plate and the negative electrode plate due to winding deviation.

Next, the conventional alkaline storage battery b1 shown in Table 2
When compared with the alkaline storage batteries a1 and a2 of the embodiment, the capacities are substantially equal. This shows that the decrease in the battery capacity due to the reduction in the hole diameter at the winding start portion of the conductive core is very slight. In the present embodiment, the hole diameter and the plate thickness at the winding start portion of the conductive core body are changed with respect to the portion excluding the winding start portion.
Even if the number of holes in the conductive core is smaller than that of the portion excluding the portion where the winding starts, the tensile strength in the winding direction is also increased. Therefore, the same effect as that of the present embodiment can be obtained.

Further, in the conductive core, the porosity of the winding start portion is made smaller than the porosity of the portion other than the winding start portion, and the plate thickness of the winding start portion is smaller than that of the winding start portion. It is considered that the combination of making the part thicker than the part to be removed is more effective. Further, the present embodiment is a positive electrode plate,
Although the conductive core with increased tensile strength of the present invention was used for the two plates of the negative electrode plate, even when the conductive core was used for either the positive electrode plate or the negative electrode plate, the conductive core was used. Since it is possible to suppress the elongation of the conductive core body while maintaining the capacity, the used electrode plate is considered to have the same effect as that of the present embodiment, compared to the case where the conductive core body of the conventional example is used. Can be

In the present embodiment, an alkaline storage battery was implemented and evaluated. However, any battery using a spiral electrode body can be applied regardless of the type of battery.
A prismatic battery is applicable as long as it uses a spiral electrode body.

[0042]

As described above, according to the present invention, in a strip-shaped conductive core having a large number of holes used for a spiral electrode body, the tensile strength of the winding start portion is such that the winding start portion has By adopting a structure that is larger than the tensile strength of the removed portion, the positive electrode plate and the negative electrode plate manufactured using the conductive core can be wound in the winding step of manufacturing the spiral electrode body. Elongation in the rotating direction is reduced, and winding deviation and deformation of the spiral electrode body can be prevented. Further, in the electrode plate using the conductive core, the filling density of the active material is ensured, and a decrease in electrode plate capacity is suppressed to a low level.

Therefore, the present invention is effective for producing a battery having a high energy density with a high yield.

[Brief description of the drawings]

FIG. 1 is a diagram showing a conductive core according to a first embodiment of the present invention.

FIG. 2 is a view showing a pattern of a conductive core.

FIG. 3 is a view showing a conductive core according to a second embodiment of the present invention.

FIG. 4 is a view showing a winding step of manufacturing a spiral electrode body.

FIG. 5 is a view showing a structure of a battery provided with a spiral electrode body.

FIG. 6 is a view showing a conventional conductive core.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode plate 2 Negative electrode plate 3 Separator 4 Spiral electrode body 5 Outer can 6 Sealing lid 10 Conductive core of Embodiment 1 21 Conductive core 22 Conductive core piece 50 Core 100 Separator roll 200 Conductive core Hole opened in

Claims (4)

[Claims] 1. A strip-shaped conductive core used for a spiral electrode body and having a plurality of holes formed therein, wherein the conductive core has a tensile strength at a winding start portion thereof.
A conductive core for a battery electrode plate, wherein the conductive core has a tensile strength greater than that of a portion excluding the winding start portion. 2. In the conductive core, a porosity, which is a ratio of holes occupied on the surface of the core at the winding start portion, is as follows:
2. The conductive core for a battery electrode plate according to claim 1, wherein the porosity of the portion excluding the winding start portion is smaller than the porosity. 3. The battery according to claim 1, wherein, in the conductive core, a plate thickness of the winding start portion is larger than a plate thickness of a portion excluding the winding start portion. Conductive core for electrode plates. 4. A power generating element in which a spiral electrode body obtained by winding a positive electrode plate and a negative electrode plate via a separator is impregnated with an electrolytic solution, an outer can containing the power generating element, and the outer case. A battery having a sealing lid for closing an opening of a can, wherein the conductive core according to any one of claims 1 to 3 is used for at least one of the positive electrode plate and the negative electrode plate. Features battery.