JP2697313B2 - Cylindrical battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a cylindrical battery having an electrode group in which a positive electrode plate and a negative electrode plate are spirally wound with a separator interposed therebetween.

[0002]

2. Description of the Related Art Conventional cylindrical batteries include, for example, Ni-C
As shown in FIG. 3, both a positive electrode plate and a negative electrode plate are formed by welding a strip-shaped current collecting lead to the center of an electrode plate and winding these electrode plates via a separator as shown in FIG. There are an electrode group 3 and an electrode group 3 in which current collecting leads 4 and 5 are provided at the ends of the electrode plates as shown in FIG.

[0003]

Heretofore, a flat metal plate as shown in FIG. 5A has been used as a current collecting lead to be welded to an electrode plate. When such a lead is used, the shape of the electrode group is significantly affected by the shape of the current collecting lead at the center of the electrode group. For example, as shown in FIG. 5B, a case where the winding cross section of the electrode plate group does not become a perfect circle occurs. in this case,
Since it is difficult to insert the electrode group into the cylindrical case, and a space is wasted even when the electrode group is inserted, the packing density of the electrode group in the cylindrical case is limited, and a high capacity cannot be obtained.

Therefore, a band-shaped metal plate lead curved in a semicircular arc in accordance with the curvature of the center of the winding of the electrode group as shown in FIG. 6 was examined. 1) is also curved, which makes it difficult to weld to an external terminal such as a sealing plate, and that this portion is hardly bent,
As shown in FIG. 7A, when the current-collecting lead is deformed into an S-shape when the sealing plate is inserted, a stress is generated, and the electrode group is easily damaged.

[0005] Even if an external terminal such as a sealing plate is welded to such a current collecting lead to form a battery, the fact that the current collecting lead is easily damaged as described above means that the reliability of the battery is low. However, there is a disadvantage that the safety is remarkably reduced.

[0006]

According to the present invention, such a disadvantage is solved by improving a current collecting lead. Specifically, as shown in FIG. 4, the current collecting lead is formed of a band-shaped metal plate curved in a semicircular arc in accordance with the curvature of the center of the winding of the electrode plate group. It has a shape having a cut groove and a flat plate part in a part.

[0007]

With such a configuration, when the lead portion is deformed, the portion is curved through the cut groove, so that stress is hardly generated, the electrode group is not easily damaged, and the lead is taken out of the electrode plate. Since the flat part shown by 12 in FIG. 4 is provided in a part of the lead part, welding to an external terminal such as a sealing plate becomes easy.

[0008] Therefore, a battery having a packing density close to ideal, which can obtain a dense spiral electrode group closer to a perfect circle, can be obtained. Further, welding between the external terminal such as a sealing plate and the lead portion is facilitated, and the electrode plate group is hardly damaged, thereby greatly improving the reliability and safety of the battery.

[0009]

The present invention will be described below in detail with reference to examples.

FIG. 1 shows MnO as a positive electrode used in this embodiment.
_2. A longitudinal sectional view of a cylindrical battery using lithium metal as a negative electrode is shown. In the figure, 1 is a battery case processed from a stainless steel plate having resistance to organic electrolyte, 2 is a sealing plate, 3 is an electrode plate group, and a positive electrode plate and a negative electrode plate are spirally wound several times via a separator. It is stored. The positive electrode lead 4 is drawn out from the positive electrode plate and connected to the sealing plate 2, and the negative electrode lead 5 is drawn out from the negative electrode plate and connected to the inner bottom of the battery case 1. 6 is an insulating ring at the bottom.

As shown in FIG. 4, the lead used for the positive electrode plate has cut grooves 11 on both left and right sides, and its tip (upper end) is made of a strip-shaped Ti plate having a flat plate portion 12.
As the positive electrode plate, one obtained by welding the lead to the end of the electrode plate and then bending the portion 14 of the lead in contact with the electrode plate into an arc shape.

The cathode plate is prepared by mixing 100 parts by weight of MnO ₂ powder, 3 parts by weight of acetylene black, 4 parts by weight of graphite, and 7 parts by weight of a fluororesin binder, and suspending the mixture in an aqueous solution of carboxymethylcellulose. I made it. This paste was applied to both sides of an aluminum foil having a thickness of 0.03 mm, dried and rolled to a thickness of 0.22 mm, a width of 40 mm, and a length of 280 mm, and the above-mentioned leads were attached to obtain a positive electrode plate.

The negative electrode plate was prepared by attaching Ni leads to a lithium foil having a thickness of 0.12 mm, a width of 42 mm and a length of 300 mm.

The above positive and negative electrode plates have a thickness of 0.025 mm and a width of 4 mm.
It was wound through a polypropylene separator having a length of 6 mm and a length of 670 mm, and housed in a battery case having a diameter of 13.8 mm and a height of 50 mm. As the electrolytic solution, a solution prepared by dissolving lithium perchlorate at a ratio of 1 mol / l in an equal volume mixed solvent of propylene carbonate and ethylene carbonate was used. This battery was sealed to obtain a battery of Example.

[Comparative Example 1] A battery of the embodiment was constructed under the same conditions as the battery of the embodiment except that a strip-shaped metal plate made of a Ti material having neither a cut groove nor a curved arc was used in the lead of the positive electrode plate. Was performed to obtain a battery of Comparative Example 1.

COMPARATIVE EXAMPLE 2 The battery of Comparative Example 2 was manufactured under the same conditions as those of the battery of Example 2 except that a strip-shaped metal plate made of a Ti material having no slit was used for the lead of the positive electrode plate. did.

After observing the winding state of the electrode group of the batteries of the above-mentioned Examples and Comparative Examples, 10
00 pieces were left at 60 ° C. for 3 days, and the open circuit voltage was measured. Further, the battery after being left was disassembled, and the state of welding between the positive electrode lead and the sealing plate was observed.

First, in the battery of Comparative Example 1, when the core diameter is 3 mm (indicated by d in FIG. 5B), the shape of the electrode group after forming the electrode group is not cylindrical, and its cross section is not shown. 5 (b), and it was difficult to insert it into the cylindrical case. In addition, when the size of the electrode plate or the like was adjusted and the above electrode group was inserted into the cylindrical case, the packing density of the electrode group in the cylindrical case was reduced by about 20%.

Then, by reducing the diameter of the winding core, an electrode plate group having a cross section close to a perfect circle was obtained as shown in FIG. 5 (c), and a charge / discharge capacity close to an ideal was obtained. However, when the external short circuit was intentionally performed, the current collecting lead generated heat and sometimes ignited due to the small cross-sectional area of the current collecting lead. Such a battery is not preferable in terms of safety and is not suitable as a practical battery.

Next, in Comparative Example 2 in which only the current collecting lead was bent, the defect as in Comparative Example 1 did not occur. However, when the battery was disassembled and the state of the electrode group was observed, the group was deformed as shown in FIG.
As shown in Table 1, as shown in Table 1, there were 80 out of 1,000 leads that had broken the current-collecting leads and broke the separator to cause a short circuit.

[0021]

In addition, spot welding between the current collecting lead and the sealing plate was difficult, and there were 85 spot defects out of 1,000 where the spot welds were dropped during battery disassembly.

On the other hand, in the embodiment, the above-mentioned defect was not observed at all. In this embodiment, MnO is used for the positive electrode.
₂ , a battery using metallic lithium for the negative electrode was shown. As a result of examination, similar effects were obtained in the case of a Ni-Cd battery, a lithium fluoride graphite battery, and a battery using LiCoO _{2 for} the positive electrode and a carbon material for the negative electrode. was gotten. In particular, the effect was great when the electrode plate was thin.

The effective shape of the cut groove is triangular as shown in FIG. 9A or semicircular as shown in FIG. 9B. Further, the position of the cut groove was effective when the distance from the upper end face of the group to the center of the groove (l shown in FIG. 9C) was 1 to 5 mm, and especially when the distance was 3 mm.

[0024]

As is apparent from the above description, in a cylindrical battery in which the current collecting lead is arranged at the center of the winding of the electrode plate group, the current collecting lead is perpendicular to the winding direction at the end of the electrode plate. The present invention is a strip-shaped metal plate which is installed at a center and is curved in a semicircular arc in accordance with the curvature of the winding center portion, and has a cut groove and a flat plate portion in a part of a lead portion taken out of the electrode plate. Is effective in improving battery reliability and manufacturing workability.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a cylindrical battery according to an embodiment of the present invention.

FIG. 2 (a) is a development view of a cylindrical battery electrode plate in which a current collecting lead is placed at an end of an electrode plate and is arranged at a winding center of the electrode plate group.

FIG. 3A is a development view of a cylindrical battery electrode plate in which a current collecting lead is arranged at the center of the electrode plate. FIG.

FIG. 4 is a diagram showing a current collecting lead according to the embodiment of the present invention.

5A is a view showing a current collecting lead in Comparative Example 1. FIG. 5B is a view showing a winding state of an electrode group. FIG. 5C is a view showing a winding state of an electrode group.

FIG. 6 is a diagram showing a current collecting lead and an electrode group in Comparative Example 2.

FIG. 7 is a diagram showing a bent state of a current collecting lead after closing a battery;

8A is a diagram showing deformation of an electrode group after sealing a battery in Comparative Example 2; FIG. 8B is a diagram showing the state of breakage of a current collecting lead;

9A, 9B, and 9C are views showing the positions and shapes of cut grooves of a current collecting lead.

[Explanation of symbols]

 3 Electrode plate group 11 Notch groove 12 Flat plate part 14 Contact part with electrode plate

Claims (1)

(57) [Claims] An electrode group formed by winding a positive electrode plate and a negative electrode plate with a separator interposed therebetween, and a current collecting lead provided at at least one end of the positive electrode plate and the negative electrode plate is provided in the electrode group. In the cylindrical battery disposed at the center of the winding, the current-collecting lead is formed in a belt-like shape that is curved in a semicircular arc in accordance with the curvature of the center of the winding, which is installed perpendicular to the direction of the winding at the end of the electrode plate. A cylindrical battery having a notch groove and a flat plate portion in a part of a lead portion taken out of the electrode plate.