JPH0535549B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a cylindrical lithium battery, and more specifically, the present invention relates to a cylindrical lithium battery, in which lithium is formed into a hollow cylinder as a negative electrode,
Regarding a cylindrical lithium battery using hollow lithium such as lithium foil wound in a hollow spiral, improving the structure around the bottom of the negative electrode to facilitate manufacturing and stabilize battery performance. .

<Prior art> For example, an inside-out type cylindrical lithium battery is known as the above-mentioned cylindrical lithium battery, in which a suitable conductive agent or binder is added to a positive electrode active material such as manganese dioxide or graphite fluoride. In addition, after kneading, a positive electrode mixture that has been pressure-molded into a hollow cylindrical shape is inserted into the positive electrode can while being in close contact, a separator is attached to the outer periphery of the negative electrode, and then this negative electrode and separator are placed in the hollow part of the positive electrode mixture. A structure is adopted in which they are inserted together.
The method of attaching a separator to the outer periphery of a hollow lithium negative electrode is to wrap a sheet-like separator around a lithium negative electrode that has been formed into a hollow shape in advance, and then push the lower end of the separator into the lithium hollow part to create a bottom. A separator in which hollow lithium is inserted into a separator formed into a cylindrical bottom is used.

<Problems to be Solved by the Invention> However, the conventional cylindrical lithium battery using the above-mentioned type has the following problems.
First, in the case of a type using a sheet-like separator, a step of pushing the lower end portion of the separator into the lithium hollow space is required in the battery assembly process, but such a pushing step is difficult to mechanize. Moreover, it is difficult to insert the negative electrode and separator into the positive electrode mixture hollow part while keeping the separator folded into the hollow part, which complicates the battery manufacturing process and causes high costs. There is a drawback that insufficient folding can lead to poor battery assembly and deterioration in battery performance. In addition, in the case of using a separator molded into a cylindrical shape with a bottom, it is difficult to increase the adhesion between the lithium negative electrode and the separator because the hollow lithium negative electrode is inserted into the bag-shaped separator, and the battery's internal resistance There is a disadvantage that this increases the battery performance and causes a decrease in battery performance. Another problem is that the battery performance varies depending on the degree of adhesion between the lithium and the separator.

<Means for Solving the Problems> The gist of the cylindrical lithium battery of the present invention is that it has a cup-shaped bottom paper between the bottom of a hollow lithium negative electrode around which a separator is wound and the bottom of the positive electrode can. It is something to do.

<Function> By using the above means, it is not necessary to push the separator into the lithium hollow part in the battery manufacturing process, and there is also no reduction in battery performance or variation in performance due to poor adhesion between lithium and the separator.

<Example> In Fig. 1, 1 is a stainless steel positive electrode can with a positive electrode terminal 1a formed on the bottom; 2 is a positive electrode can made of stainless steel with a positive electrode terminal 1a formed on the bottom; 2 is a positive electrode can made of manganese dioxide, mixed with carbon powder, polytetrafluoroethylene, etc., and then pressure-molded. 3 is a hollow lithium negative electrode obtained by winding lithium foil into a cylindrical shape; 4 is a separator made of polypropylene nonwoven fabric; 6 is a punched lithium negative electrode provided on the hollow lithium negative electrode 3; A lead wire electrically connected between a current collector (not shown) such as metal and the sealing plate 7; 7 is a sealing plate made of thin stainless steel; 8
is a negative electrode terminal plate; 9 is an annular sealing gasket made of polypropylene; 10 is a heat-shrinkable tube; 1
1 is a cup-shaped bottom paper made of polypropylene nonwoven fabric or polypropylene sheet.

The cylindrical lithium battery having the above structure is manufactured by the following steps. First, as shown in FIGS. 2A and 2B, a sheet-like separator 4 is placed around the outer periphery of the hollow lithium negative electrode 3, and this is placed on the hollow lithium negative electrode 3.
Wrap it around the outside. Meanwhile, in a separate step, the hollow cylindrical positive electrode mixture 2 is inserted into the positive electrode can 1, and the cup-shaped bottom paper 11 is placed on the hollow portion 2a of the hollow cylindrical positive electrode mixture 2. Then, the hollow lithium negative electrode 3 with the separator 4 attached as described above is positioned at the center of the upper part of the opening 1b of the positive electrode can 1 as shown in FIG. The hollow cylindrical positive electrode mixture 2 is placed on the cup-shaped bottom paper 11.
into the hollow part 2a. After the above steps are completed, a non-aqueous electrolyte is injected by a known method, the sealing gasket 9, the lead wire 6, the sealing plate 7, the negative electrode terminal plate 8, etc. are attached, and the opening 1b of the positive electrode can 1 is beaded and curled. and heat-shrinkable tube 1 on the outer periphery.
0 to form the cylindrical lithium battery shown in FIG.

<Effects of the Invention> As described above, the cylindrical lithium battery of the present invention has a structure in which a cup-shaped bottom paper is provided between the bottom of the hollow lithium negative electrode around which the separator is wound and the positive electrode can. In the process, there is no need to push a single separator into the lithium negative electrode, eliminating the complexity of manufacturing caused by such a process, and making it easier to mechanize the manufacturing process, making battery manufacturing easier and reducing costs. etc. In addition, in the battery manufacturing process, the separator is wound around the hollow lithium negative electrode in advance and inserted into the hollow part of the positive electrode mixture, so good adhesion between the lithium negative electrode and the separator can always be ensured, eliminating problems caused by poor adhesion. This has the effect of improving battery performance by eliminating an increase in internal resistance, and stabilizing battery performance by preventing variations in battery performance due to variations in the degree of adhesion.

Furthermore, the presence of such a cup-shaped bottom paper allows the insulation between the bottom of the lithium negative electrode and the bottom of the positive electrode can to be completely maintained over a long period of time, which has the advantage of contributing to improved discharge performance and stock performance of the battery. There is also.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIGS. 2A to 2E are explanatory diagrams showing a part of the manufacturing process of the embodiment. 1... Positive electrode can, 2... Hollow cylindrical positive electrode mixture, 3
...Hollow lithium negative electrode, 4...Separator, 1
1...Cup-shaped bottom paper.

Claims (1)

[Claims] 1. A cylindrical lithium battery characterized by having a cup-shaped bottom paper between the bottom of a hollow lithium negative electrode around which a separator is wound and the bottom of a positive electrode can.