JP2001160411A - Cylindrical secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylindrical secondary battery that prevents an internal short-circuit in the central area of spiral and is excellent in cycle characteristic. SOLUTION: A cylindrical secondary battery that has a group of spiral pole plates, of which positive and negative pole plates that are equipped with pole plate base and active material supported by pole plate base are wound via a separator. The ends at the central part of the spiral of the positive poly plate and negative poly plate are made asymmetric in their shapes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cylindrical secondary battery.

[0002]

2. Description of the Related Art Principal secondary batteries currently in practical use include lead storage batteries, nickel cadmium storage batteries, nickel metal hydride batteries, silver zinc oxide batteries, and lithium ion batteries.

A lead-acid battery uses lead dioxide as a positive electrode active material, lead as a negative electrode active material, and dilute sulfuric acid as an electrolyte, and has an operating voltage of about 2V. This battery has a balance in terms of quality, reliability, and price, and is widely used for automobiles, electric vehicles, uninterruptible power supplies, and the like. In recent years, the technology of miniaturization has been advanced, and its usefulness has been increased for various cordless devices.

A nickel cadmium storage battery uses nickel oxyhydroxide as a positive electrode active material, cadmium as a negative electrode active material, and an aqueous solution of potassium hydroxide as an electrolyte.
V operating voltage. This battery is widely used mainly for consumer equipment because it has features such as low internal resistance, capable of discharging large current, long cycle life, strong resistance to overcharging and overdischarging, and wide operating temperature range. .

A nickel-metal hydride battery uses nickel oxyhydroxide as a positive electrode active material, a hydrogen storage alloy as a negative electrode active material, and an aqueous solution of potassium hydroxide as an electrolytic solution. The operating voltage is about 1.2V. It has a high energy density and has been put to practical use mainly in various consumer devices.

[0006] A silver zinc oxide battery uses silver oxide as a positive electrode active material,
It uses zinc as the negative electrode active material and potassium hydroxide as the electrolyte. While having high output and high energy density, large ones are mainly used for space and deep sea because of their high cost, while small ones are widely used for watches and calculators.

[0007] Lithium ion batteries use Li as a positive electrode active material.
It uses a Li metal composite oxide such as CoO ₂ , LiNiO ₂ , and LiMn ₂ O ₄ , a carbonaceous material for the negative electrode, and an organic solution for the electrolyte, and has an operating voltage on the order of 3V. Due to advantages such as high operating voltage, high energy density, and no memory effect, applications for consumer use are rapidly expanding.

[0008] The above-mentioned practical secondary batteries are provided in the form of a prism, a cylinder, a button, a sheet or the like depending on the application.

As shown in FIG. 1, a cylindrical secondary battery is formed by forming a thin and long strip-shaped positive electrode 1, a negative electrode 2, and a negative electrode 2 in a spiral shape through a separator 3 in a spiral shape. It is housed in a battery container (not shown). In addition, the example of FIG.
Although this is an example in which an electrode base having the pole lugs 5 is used, there is also a method of collecting current using a current collecting member or collecting current using a lead using an electrode base having no pole lugs.

[0010]

The conventional spiral electrode group is manufactured by winding positive and negative electrodes of substantially the same shape via a separator, and the upper and lower edges 6a, 6b on the spiral center side X of the positive and negative electrodes. Is generally 90 ° as shown in FIG. For this reason, there is a problem that the edge portion 6 breaks through the separator and causes an internal short circuit with the counter electrode plate.

As a measure for preventing such an internal short circuit, for example, as disclosed in Japanese Patent Application Laid-Open No. Hei 10-270014, the edge of the electrode at the center of the spiral is trimmed, a curve is formed, Or the like is coated with an insulating resin. FIG. 3 shows the former example.

Although the internal short circuit resulting from the electrode plate edge 6 on the spiral center side X breaking through the separator is considerably improved by these, in the former case, the separator at the opposite part of the positive and negative electrodes at the spiral central part is located. There has been a problem that an internal short circuit still occurs due to breakage, and the latter case leads to an increase in cost.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object thereof is to prevent, at a lower cost, an internal short circuit caused by the edge of the plate near the center of the spiral penetrating the separator. It is an object of the present invention to provide a rechargeable cylindrical secondary battery.

[0014]

According to the first aspect of the present invention,
In a cylindrical secondary battery having a spiral electrode group in which a positive / negative electrode plate having an electrode substrate and an active material held on the electrode substrate is wound via a separator, the spiral center of the positive electrode plate and the negative electrode plate A cylindrical secondary battery having asymmetrical side ends. This provides a cylindrical secondary battery that can effectively and inexpensively prevent an internal short circuit caused by the electrode plate corner on the spiral center side breaking through the separator.

The invention according to claim 2 is the cylindrical secondary battery, wherein the positive electrode active material is lead dioxide, the negative electrode active material is lead, and the electrode plate base is lead or a lead alloy. This provides a cylindrical lead-acid battery that can more effectively and inexpensively prevent an internal short circuit caused by the electrode plate corner on the spiral center side breaking through the separator.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the asymmetric shape of the spiral center end X of the positive electrode plate 1 and the negative electrode plate 2 means that the positive electrode plate 1 and the negative electrode plate 2 are rolled up and aligned. Means that the end of the spiral center side of the positive electrode plate 1 and that of the negative electrode plate are not completely overlapped.

For example, as shown in FIG. 4A, the positive electrode plate 1 has a straight edge extending from the upper right to the lower left of the paper, and as shown in FIG. 4B, it has a straight edge extending from the upper right to the lower right of the paper. When the negative electrode plate 2 is overlaid, the state shown in FIG.

Further, for example, as shown in FIG. 5A, a positive electrode plate 1 having an inverted S-shaped edge extending from the upper right corner to the lower left of the paper, and as shown in FIG. When the negative electrode plate 2 having the S-shaped edge directed in the direction is overlapped, the state shown in FIG. With this configuration, even if the separator breaks through at the edge of the spiral center of the electrode plate, the chance of contact with the counter electrode plate is reduced, and the occurrence of an internal short circuit can be reduced.

In FIGS. 4 and 5, both edges on the spiral center side X are schematically drawn at acute angles, but it is preferable to form them with curved lines from the viewpoint of preventing separator breakage. Further, as shown in FIGS. 4 and 5, when the upper and lower edges 6a and 6b of the paper have a phase shift in the winding direction, the magnitude of the phase shift is equal to or more than the innermost circumference of the spiral electrode group. It is more preferable from the viewpoint of winding property and prevention of short circuit.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment using a lead storage battery having a nominal capacity of 5 Ah will be described below. First, using a 0.6mm thick lead alloy foil,
An electrode substrate having a width of 80 mm × a length of 500 mm and 5 mm × 7 mm cells (not shown) arranged in 12 rows × 58 columns was formed by punching. Note that lead may be used instead of a lead alloy.

As a conventional product, as shown in FIG. 2, a positive and negative electrode plate having the same spiral center end X and a rectangular shape and having a target shape according to the present invention was prepared.

The electrode substrate of Example 1 is a positive electrode plate 1 having a straight edge extending from the upper right corner 6a to the lower left direction 6b, as shown in FIG. The negative electrode plate 2 having a phase shift a of 10 mm in the direction and a linear edge extending from the upper right corner or 6a to the lower right direction 6b as shown in FIG. 6b having a phase shift a of 10 mm in the winding direction was prepared. When these are superimposed,
The state is as shown in FIG.

The electrode substrate of Example 2 had the same configuration as that of Example 1 except that both corners on the spiral center side were formed with a curve having a radius of 3 mm.

The electrode substrate of the third embodiment has the same configuration as that of the second embodiment except that the phase shifts a and b of both edges are 16 mm. 3 to 5, the illustration of the pole ears is omitted.

An electrode plate was manufactured using the above-described various electrode plate substrates. The positive electrode plate was prepared by kneading a lead powder having an oxidation degree of 70% (metal lead 30%, lead monoxide 70%) and dilute sulfuric acid to obtain an active material paste, and then applying them to both surfaces of the electrode substrate. The theoretical capacity of the positive electrode is 12 Ah. The negative electrode has an oxidation degree of 70%
A small amount of carbon powder and lignin were added to lead powder (metal lead 30%, lead monoxide 70%) and kneaded with dilute sulfuric acid to obtain an active material paste, which was then applied to both surfaces of the electrode plate substrate. . The theoretical capacity of the negative electrode is 16 Ah. A spiral electrode plate group was obtained from these positive and negative electrode plates via a glass mat separator.

The spiral electrode group has an inner diameter of 4.5 mm and an innermost dimension of about 14 mm. Therefore, Example 3
The phase shifts a and b between 6a and 6b are both 16 mm, which is larger than the innermost peripheral dimension 14 mm, but small in the first and second embodiments.

Next, after inserting the spirally wound electrode group into a cylindrical container made of resin and sealing the same, a dilute sulfuric acid aqueous solution having a predetermined specific gravity is injected from the injection port under reduced pressure, and the solution is supplied at a constant current of 0.25 C. A battery case formation was performed for an hour to obtain a cylindrical sealed lead storage battery. still,
The straps, poles, lids, and the like were attached in a conventional manner. These cylindrical sealed lead-acid batteries were discharged at a discharge rate of 0.2 CA. Further, in order to evaluate the cycle life, a charge / discharge cycle test of 1 CA discharge (1.7 V end voltage), 1 CA constant current × 2.45 V constant voltage charge (1.5 hours) was performed. FIG. 6 shows the cycle life test results.

In these figures, a, b, c and d are the results of the conventional example, the first embodiment, the second embodiment and the third embodiment, respectively. From these results, it can be seen that in the cycle life, the conventional example <Example 1 <Example 2 <Example 3.

As a result of disassembling the product after the end of the cycle test and investigating the cause of reaching the service life, the frequency of occurrence of the separator breakage due to the electrode plate edge at the center of the spiral is 100% of the conventional example and 100% of the conventional example. > Example 1 (85%)>
Example 2 (79%)> Example 3 (71%).

It can be seen that the product of the present invention is superior in cycleability to the conventional product, because the internal short circuit due to breakage of the separator at the edge of the electrode plate at the center of the spiral is reduced. Although the reason why the cycle life performance of Example 3 was better is not necessarily clear, it is presumed that the winding is performed more reliably.

According to a test conducted separately, as compared with the present invention, as shown in the above-mentioned Japanese Patent Application Laid-Open No. Hei 10-270014, the spiral end covered with an insulating tape had slightly better cycle characteristics. In the latter case, there is a problem that extra man-hours are required, leading to an increase in cost, and the present invention can be said to be better in terms of performance and cost. Also,
In the case shown in FIG. 5, as well as in the case of FIG. 4, the spiral center side ends of the positive electrode plate and the negative electrode plate are made asymmetrical without depending on the shape of the spiral center side end. Thereby, it is recognized that the effect of preventing short circuit is increased, and the operation and effect of the present invention is exhibited.

Although the above embodiment relates to a cylindrical lead-acid battery, similar effects have been found in a cylindrical lithium-ion secondary battery and a cylindrical alkaline secondary battery.

[0033]

As described above, according to the present invention, it is possible to provide a cylindrical secondary battery having good cycle characteristics by reducing an internal short circuit caused by the electrode plate edge on the spiral center side of the spiral plate group. it can.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a spiral electrode group.

FIG. 2 is a schematic view showing a spiral center side end of a spiral electrode group;

FIG. 3 is a schematic diagram showing a conventional example.

FIG. 4 is a schematic view showing one embodiment of the present invention.

FIG. 5 is a schematic view showing one embodiment of the present invention.

FIG. 6 is a diagram showing test results.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode plate 2 Negative electrode plate 3 Separator 4 Spiral electrode group 5 Electrode lug 7 Electrode edge X End of spiral electrode center side

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H028 AA05 BB07 CC00 CC05 CC13 EE01

Claims (2)

[Claims] 1. A cylindrical secondary battery comprising a spirally wound electrode plate group comprising a positive and negative electrode plate provided with an electrode plate substrate and an active material held on the electrode plate substrate, with a separator interposed therebetween, comprising: A cylindrical secondary battery in which a spiral center end of a negative electrode plate has an asymmetric shape. 2. The method according to claim 1, wherein the positive electrode active material is lead dioxide, the negative electrode active material is lead,
2. The cylindrical secondary battery according to claim 1, wherein the electrode substrate is made of lead or a lead alloy.