JPH0535569Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> This invention relates to cylindrical lithium batteries, and in particular to a negative electrode lead plate that protrudes from the separator and can be precisely spot-welded to the center of the inner bottom of the battery case. This invention relates to a plate positioning structure.

《Prior art》 Cylindrical lithium batteries are made by laminating metallic lithium and a positive electrode mixture that constitute a negative electrode on the front and back sides of a separator, and then layering another separator on the positive electrode mixture side, which is then stacked in a spiral shape. A cylindrical power generation element is formed by winding the power generation element, and this power generation element is housed in a bottomed cylindrical case with a bottom plate disposed at the bottom, and the lower part of the current collector in contact with the metal lithium is The negative electrode lead plate protruding from the casing is bent and electrically connected to the inner bottom surface forming the negative electrode terminal portion of the case by spot welding.

The spot welding method involves bending the negative electrode lead plate, positioning it on the bottom of the bottom plate, and placing it in the inner bottom of the case.Then, insert the electrode rod through the center hole formed in the center of the power generation element, and is pressed against the negative electrode lead plate and the inner bottom of the case through the center opening of the bottom plate, and spot welded with the other electrode disposed on the bottom side of the case while sandwiching the two.

<<Problems to be Solved by the Invention>> However, during the above-mentioned work process, the negative electrode lead plate may not always be properly bent to a desired normal position.

If the bending condition is poor, the bent end of the negative electrode lead plate will not be located at the center of the bottom plate, and if it is placed in a case in this state and spot welded to the center of the bottom of the case, the bent end will not be located at the center of the bottom plate. Because it is not located in the center, spot welding may not actually be possible, or even if it is welded, only a small portion may result in a poor connection, which is a factor in lowering product yield and battery performance.

This idea was devised in view of the above problems, and its purpose is to ensure that the negative electrode lead plate is located in the center of the bottom plate when bending, thereby making it possible to place the negative electrode lead plate in the center of the bottom plate. The present invention provides a positioning structure for a negative electrode lead plate in a cylindrical lithium battery that enables reliable welding.

<Means for solving the problem> In order to achieve the above-mentioned object, this invention stacks metallic lithium and a positive electrode mixture on the front and back sides of a separator, and further places another separator on the side of the positive electrode mixture. Then, the positive electrode mixture is wound on the inside to form a spiral power generation element, and the power generation element is housed in a bottomed cylindrical case via a bottom plate on the lower surface of the power generation element. In a cylindrical lithium battery in which a negative electrode lead plate protruding from the bottom is bent onto the surface of the bottom plate and connected to the inner bottom of the case by spot welding, a bend is formed at the center of the surface of the bottom plate. A pair of positioning projections were provided to sandwich the negative electrode lead plate.

<<Operation>> According to the above structure, when the negative electrode lead plate is bent, the bent end is positioned and fixed between the positioning protrusions, so that spot welding can be performed reliably.

<<Example>> Hereinafter, an example of this invention will be described in detail using the drawings.

In FIG. 1, 1 and 1' are separators made of nonwoven fabric, 2 is metal lithium that constitutes the negative electrode pasted on the surface of the separator 1, and 3 is a positive electrode mixture pasted on the back surface of the separator 1.

The positive electrode mixture 3 is placed in the center of the back surface of the separator 1.
A positive electrode current collector 4 made of metal thin plates coated and bonded is stacked, and a positive electrode lead plate 4a spot-welded to the center thereof projects from the upper edges of the separators 1, 1'.

Further, near the end of the winding on the surface side of the separator 1, a negative electrode current collector 5 made of a thin metal plate made of stainless steel or the like is placed in electrical contact with the lithium 2.

The negative electrode current collector 5 is formed by punching a thin metal plate such as stainless steel using a press, and includes a plate-shaped current collecting part 5a that contacts the lithium 2, and a current collecting part 5.
It consists of a negative electrode lead plate 5b integrally extending upward from the upper edge of one end of the negative electrode lead plate 5b, and a wide part 5c formed at the bent end of the negative electrode lead plate 5b, and the negative electrode lead plate 5b and the separator 1, It protrudes from the lower edge of 1'.

In the above configuration, the separators 1 and 1' are wound in a spiral shape from the winding start end A (appears on the right side in the figure) with the positive electrode mixture 3 side facing inside and the lithium 2 side facing outside. , second
As shown in the figure, the separator 1 is formed into a cylindrical power generation element 7 whose outer periphery is surrounded.

The negative electrode lead plate 5 is located below the power generating element 7.
b protrudes, and a positive electrode lead plate 4a protrudes from the upper outer peripheral side.

In this state, a bottom plate 8 made of an insulator such as polypropylene was placed on the lower surface of the power generation element 7, and the negative electrode lead plate 5b was inserted into the notch 8c of the bottom plate 8 and bent toward the lower surface of the bottom plate 8. It is housed in a cylindrical case 9 with a bottom.

A central hole 8a is opened in the center of the bottom plate 8, and a pair of protrusions 8b are protruded from the surfaces on both sides of the hole 8a.

The width d between the protrusions 8b is about 0.1 mm smaller than the width of the negative electrode lead plate 5b.

When the negative electrode lead plate 5b having the above structure is bent from its bent base, the negative electrode lead plate 5b is sandwiched between the protrusions 8b and positioned at the center of the bottom plate 8, as shown in FIG. Ru.

Further, in the positioned state, the wide portion 5c contacts the tip of the protrusion 8b like a brim to prevent the negative electrode lead plate 5b from jumping up due to springback, and fixes it in the positioned state between both protrusions 8b.

After that, the center hole 7a of the power generation element 7 and the bottom plate 8
When the electrode rod 10 is inserted through the center hole 8a of the case 9 and is spot-welded to the other electrode 11 located at the bottom of the case 9, the negative electrode lead plate 5b and the center of the bottom of the case 9 are spot-welded with high precision. It can be welded.

<<Effect>> As explained in detail using the embodiments above, in the positioning structure of the negative electrode lead plate in a cylindrical lithium battery according to this invention, when the negative electrode lead plate is bent, the bent end is used for positioning. It is positioned and fixed between the protrusions of.

Therefore, spot welding to the negative electrode lead plate can be performed reliably, contact failures due to incorrect bending positions of the negative electrode lead plate can be eliminated, and reductions in yield and battery performance caused by the negative electrode lead plate can be prevented.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view of the power generation element of the lithium battery according to this invention in an expanded state, Fig. 2 is an exploded perspective view showing the power generation element in a rolled state, and Fig. 3 shows a negative electrode lead plate folded onto the bottom plate. FIG. 4 is a partial perspective view showing a state in which the power generation element is positioned and fixed, and FIG. 1,1′...Separator, 2...Metal lithium,
3... Positive electrode mixture, 5... Negative electrode current collector, 5a... Current collecting part, 5b... Negative electrode lead plate, 5c... Wide part,
7... Power generation element, 8... Bottom plate, 8a... Center hole,
8b...Positioning protrusion, 9...Cylindrical case.

Claims (1)

[Claims for Utility Model Registration] Metal lithium and a positive electrode mixture are laminated on the front and back sides of a separator, and another separator is placed on the positive electrode mixture side, with this positive electrode mixture facing inside. The power generation element is wound to form a spiral power generation element, and this power generation element is housed in a bottomed cylindrical case with a bottom plate interposed between the lower surface thereof, and a negative electrode lead plate protruding from the bottom of the power generation element is attached to the bottom plate. In a cylindrical lithium battery that is connected to the inner bottom of the case by spot welding while being bent on the surface, a pair of bent negative electrode lead plates are provided at the center of the surface of the bottom plate. A positioning structure for a negative electrode lead plate in a cylindrical lithium battery, characterized in that a positioning protrusion is provided.