JPH0760679B2 - Bobbin type lithium battery manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a method for producing a so-called bobbin type lithium battery in which a cylindrical lithium negative electrode is filled in the center of a battery can.

<Prior Art> As a bobbin type lithium battery as described above, a lithium sheet is wound around a hollow portion of a hollow cylindrical positive electrode mixture housed in a bottomed cylindrical positive electrode can via a separator or An inside-out type is known in which a cylindrical lithium negative electrode obtained by pressure-molding metallic lithium is arranged.

In this type of battery, a non-woven sheet made of a synthetic resin is used to form a bottomed tubular (bag-shaped) separator,
A method in which a nonwoven fabric sheet is wound as a separator around the outer periphery of a cylindrical lithium negative electrode is used. And
In the case of the former type, after storing the bag-shaped separator in the positive electrode mixture hollow part in the positive electrode can, the cylindrical lithium negative electrode is stored in the bag-shaped separator in the mixture mixture hollow part, or in the bag-shaped separator. A cylindrical lithium negative electrode is housed in and the both are housed together in the hollow part of the positive electrode mixture. In the latter case, after the separator is wrapped around the outer periphery of the cylindrical lithium negative electrode, the bottom of the separator is folded over the entire circumference into the hollow portion of the lithium negative electrode to electrically isolate the bottom of the lithium negative electrode, and then these are combined. It is manufactured by the procedure of inserting it into the hollow part of the agent.

<Problems to be solved by the invention> However, the type using the bag-shaped separator is
In addition to the process of forming a bag-shaped separator by forming a non-woven sheet into a bag, the process of making a cylindrical lithium negative electrode, etc., there are two steps to store both the bag-shaped separator and the lithium negative electrode in the positive electrode can. However, there is a problem in that the manufacturing process becomes complicated. Further, when the cylindrical lithium negative electrode is inserted into the bag-shaped separator, the work is not easy, and in order to facilitate the insertion, it is necessary to make the outer diameter of lithium somewhat smaller than the inner diameter of the separator. Therefore, there is a problem that the state of close contact between the lithium negative electrode and the separator becomes poor, the distance between the electrodes becomes large after the battery is assembled, the internal resistance of the battery increases, and the discharge characteristic becomes poor.

On the other hand, in the case where a non-woven sheet is wound around a tubular lithium negative electrode, not only the two steps of forming the tubular lithium negative electrode and winding the non-woven sheet must be performed separately, but also the bottom of the separator wound around the lithium negative electrode. Terminal treatment is indispensable, especially when the inner diameter of the lithium negative electrode is small in small batteries, workability during folding and insertion into the hollow portion of the mixture after folding is extremely poor, and there is a problem that the manufacturing process becomes significantly complicated. is there.

<Means for Solving the Problems> The button-type lithium battery manufacturing method of the present invention made in view of the above problems is a bobbin-type lithium battery in which a cylindrical lithium negative electrode is filled in the center of a battery can. In the manufacturing method of the above, a sheet-shaped separator larger than this is superposed on one surface of the plate-shaped lithium negative electrode, and the separator ends protruding to both sides and the bottom surface side of the lithium negative electrode are bent to the other surface side of the lithium negative electrode. After that, the negative electrode current collector is placed on the other surface of the lithium negative electrode so as to overlap these separator end portions, and then the negative electrode current collector is pressure-bonded to the other surface of the lithium negative electrode so that these separator end portions are attached to the lithium negative electrode. The gist is to mold the lithium negative electrode together with the separator together with the other surface into a tubular shape so that the other surface faces the inner surface side.

Examples of the negative electrode current collector include sheet metal nets (stainless steel expanded metal, etc.) and metal plates (stainless steel plate with cut and raised pieces, punched metal, etc.). Then, for example, when a sheet-shaped metal net is used and pressure-bonded to the other surface of the lithium negative electrode, the end portion of the separator is sandwiched between the peripheral edge of the metal net and the lithium negative electrode and locked to the other surface of the lithium negative electrode. It Further, if a protrusion is formed at the end of the negative electrode current collector and the protrusion is made to penetrate into the lithium negative electrode during compression bonding with the lithium negative electrode, the separator end can be securely connected. Easy to do. Further, the end of the separator may be locked (fastened) to the lithium negative electrode at least until the end of the next step (step of forming into a tubular shape), and the other surface of the lithium negative electrode may be wound until the end of winding into a tubular shape. It is sufficient that it does not come off from the separator. For example, the separator end may be covered with the negative electrode current collector.

Further, only one separator may be superposed on the lithium negative electrode, but two or more separators may be superposed and used as required.

Further, as a specific example of forming the lithium negative electrode together with the separator into a cylindrical shape, a method of winding the lithium negative electrode once as described in the embodiments, or a method of winding the lithium negative electrode several times may be used.

<Operation> By using the above means, it is possible to simultaneously perform the step of forming the lithium negative electrode into a tubular shape and the step of winding the separator around the lithium negative electrode, thereby reducing the number of steps, and ensuring the close contact between the separator and the lithium negative electrode. It is possible to improve the property.

<Example> An example of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1 (A), a separator 2 made of a rectangular polypropylene nonwoven fabric sheet larger than the lithium negative electrode 1 is laid on the back surface of the rectangular negative plate 1 in the drawing. The lithium negative electrode 1 is located substantially in the center of the separator 2, and the separator end portions are projected on the upper side, the bottom side, and the left and right sides of the negative electrode 1, respectively.

Then, as shown in FIG. 1 (B), the lithium negative electrode 1
The separator ends I and II protruding to both sides of the separator are bent toward the lithium negative electrode surface side as shown in the figure, and the separator end III protruding to the lithium negative electrode bottom side is also bent similarly. After the bending, as shown in FIG. 1 (C), the lead plate 4 is welded to the central portion and the rectangular negative electrode current collector 3 made of a stainless steel net, which is slightly smaller than the lithium negative electrode 1, has a peripheral edge portion. It is placed on the surface of the lithium negative electrode 1 so as to overlap the separator ends I to III, and then the negative electrode current collector 3 is pressed in the back direction in the drawing. By this operation, the central portion of the negative electrode current collector is pressure bonded to the lithium negative electrode 1, and the separator ends I to III are sandwiched between the peripheral portion of the negative electrode current collector and the lithium negative electrode 1.

After the above operation, as shown in FIG. 1 (D), the lithium negative electrode 1 together with the separator 2 is wound once so that its surface side faces the inner surface side and molded into a tubular shape. At this time, the negative electrode current collector 3 and the lead body 4 are positioned on the inner surface side of the cylindrical lithium negative electrode 1. As shown in FIG. 1 (E), the cylindrical body thus obtained was pressure-bonded to the inner surface of a bottomed cylindrical positive electrode can 5 integrally formed with a protrusion 5a also serving as a positive electrode terminal on the bottom surface. The hollow cylindrical positive electrode mixture 6 is inserted into the central portion thereof. After inserting, by injecting the electrolytic solution and combining the insulating gasket 7, the sealing plate 8, the negative electrode terminal plate 9 and the heat-shrinkable tube 10 in the same manner as the conventional method, as shown in FIG. 1 (E). A bobbin type lithium battery can be manufactured.

Further, FIG. 2 shows a negative electrode current collector 11 formed by integrally forming a pointed projection piece 11a on the periphery of a stainless net. When this negative electrode current collector 11 is pressed against the lithium negative electrode 1 and the separator end portions I to III by the same steps, the projecting piece 11a at the current collector end portion penetrates the separator end portions I to III and the lithium negative electrode 1 of the separator end by
Locking III will become more reliable and easier.

Furthermore, as shown in FIGS. 3 (A) and 3 (B), a negative electrode current collector 12 formed by forming a large number of cut-and-raised pieces 12a on a metal plate such as a stainless plate may be used. In this case, the cut-and-raised piece 12a at the center of the current collector is used as the lithium negative electrode 1
Directly dig into the
It suffices that a penetrates the separator ends I to III and bites into the lithium negative electrode 1.

<Effect of the Invention> According to the method for manufacturing a bobbin type lithium battery of the present invention configured as described above, the step of forming the lithium negative electrode into a tubular shape and the step of winding the separator around the lithium negative electrode can be performed simultaneously. The man-hours can be reduced as compared with the conventional method, and the battery manufacturing work becomes easier accordingly. Further, since the adhesion between the separator and the lithium negative electrode can be made good, there is an effect that the internal resistance of the battery can be prevented from increasing and the battery discharge performance can be improved by that amount, and especially the inner diameter of the lithium negative electrode The utility value of a small small battery is great.

[Brief description of drawings]

1 (A) to 1 (E) are explanatory views showing a manufacturing process of an embodiment of the present invention, FIG. 2 is a perspective view showing another example of a negative electrode current collector used in the embodiment, and FIG. (A) is a plan view showing another example of the negative electrode current collector, and FIG. 3 (B) is a sectional view taken along the line AA of FIG. 3 (A). 1 …… Lithium negative electrode, 2 …… Separator, 3,11,12 ……
Negative electrode current collector, 5 ... Positive electrode can, 6 ... Positive electrode mixture, 9 ... Negative electrode terminal plate.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideaki Yagi Inventor Hideaki Yagi 5-36-11 Shimbashi, Minato-ku, Tokyo, Fuji Electric Chemical Co., Ltd. (56) Reference JP-A-60-211775 (JP, A)

Claims (3)

[Claims] 1. A method for producing a bobbin type lithium battery, which comprises a tubular lithium negative electrode inside a central portion of a battery can.
After stacking a larger sheet-shaped separator on one side of the plate-shaped lithium negative electrode and bending the separator ends protruding to both sides and the bottom side of the lithium negative electrode to the other side of the lithium negative electrode, these separator ends After placing the negative electrode current collector on the other surface of the lithium negative electrode so that it overlaps with the negative electrode current collector, and then crimping the negative electrode current collector to the other surface of the lithium negative electrode, the ends of these separators are fixed to the other surface of the lithium negative electrode. A method for producing a bobbin type lithium negative electrode, characterized in that the lithium negative electrode together with the separator is formed into a cylindrical shape so that the other surface faces the inner surface side. 2. The method according to claim 1, wherein the negative electrode current collector is a sheet metal net or a metal plate. 3. The method according to claim 1, wherein a protrusion is formed on the surface of the negative electrode current collector facing the other surface of the lithium negative electrode.