JPS606072B2 - Batteries with spiral electrode bodies - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a battery equipped with a spiral electrode body, and an object thereof is to provide a spiral electric structure that is inexpensive and has good strong discharge characteristics.

In a battery equipped with a spiral electrode body, for example, a sealed nickel-cadmium storage battery which is a typical example of a cylindrical battery, current is generally collected from the electrode terminal as follows.

That is, as shown in FIG. 6, a strip-shaped positive electrode 16 and a negative electrode 17 are spirally wound with a separator 18 interposed therebetween, and a lead terminal 19 of the positive electrode is disposed within the positive electrode. Extend the porous core metal upward to expose it, or spot weld the current collector lead to the positive electrode plate and extend it.
It is welded to a sealing plate 21 provided with a cap 20 which also serves as a positive terminal. On the other hand, for the negative electrode, the porous metal core is exposed by extending it downward in the same way as the positive electrode, or the current collector is welded 23 to the inner bottom surface of the bottomed metal container 22 by welding a Shikasumi lead. did. Regarding the negative electrode, there is also a method in which the outermost periphery of the spiral electrode body is used as the negative electrode and is pressed into contact with the side wall of the metal container to collect current to the metal container which is the negative electrode terminal, without using a current collector. In the current collecting method between the electrode and each terminal as described above, the discharge voltage of the battery decreases significantly during strong discharge, so the following proposals have been made to improve the current collecting method. That is, as shown in FIG.
and negative electrode 25 are wound in a spiral shape with a separator 26 interposed therebetween, with their positions slightly shifted in the vertical direction, and porous core metals 27 and 28 disposed in the positive and negative electrodes are exposed at the top and bottom. A metal current collector 29 is placed on the exposed core metal.
This is a so-called tableless method, in which a lath plate, silk, punched metal, plate, etc. is mounted as 30, and the current collector and the exposed core metal portion are connected by welding. In this method, compared to the above-mentioned commonly used current collection method,
Excellent strong discharge characteristics b This evening press method has an electrode structure in which the active material is held in a competitively bonded metal body with a metal core placed inside, with the metal core partially exposed. . This metal core usually does not have any openings in the exposed part, and most of the openings are made up of openings, and the exposed parts and some of the openings are plain parts. This exposed part of the core metal needs to have a width of at least about 0.5 ribs when welding it to the current collector. An exposed part of only the core metal is created to prevent powder from adhering to it.However, it is difficult to control the exposed part to a constant width industrially, and in reality it is approximately 0.5 to 1.2 There is a variation width comparable to that of a willow tree.

Therefore, the exposed part of the core metal is approximately 1. While the width of the exposed part of the core metal is sufficient when making the electrode, the width of the exposed part of the core metal becomes larger than that, resulting in an increase in loss.In addition, with this method, the exposed part of the core metal, which is not directly involved in the electrode reaction, is Therefore, in batteries where the width of the electrode is short, the occupancy rate of the exposed core metal portion becomes relatively large, and the battery capacity inevitably decreases accordingly. In this example, the active material powder is mixed with a binder solution to form a paste, which is applied to a porous metal core, dried and fixed.In the so-called paste-type electrode, Since the binding between the core metal and the active material layer is inferior to that of the firing type, it is difficult to retain the active material in the uncoated part of the core, and the exposed part of the core is separated by the hole and the uncoated part. Since both are required, there is a drawback that the width of the exposed portion inevitably increases.The present invention eliminates these drawbacks of the evening press method.

An embodiment of the present invention will be described below.

A large area of competitively-fed nickel positive electrode with a thickness of about 0.6 legs is made, with a core made of a nickel-plated perforated steel plate having a thickness of 0.06 legs placed almost in the center, and this is cut to the specified dimensions. Cut it to make unit plates for battery construction. When the end face (cut) of this unit electrode plate is cut, the metal core and the active material layer are exposed on the same surface and coexist. Next, a paste-type cadmium negative electrode with a thickness of 0.5 ribs having a large area and having the same metal core as the positive electrode disposed approximately in the center is prepared, and this is also cut into unit plates like the positive electrode. At the end face (cut) of this negative electrode unit plate, the active material layer and the intermittent core bar are exposed on the same surface and coexist. FIG. 1 shows the end face of a negative electrode unit plate, where 1 is a porous core metal that is intermittently present on the end face, and 2 is an active material layer. The intermittent porous metal core at this end face is produced by cutting the porous metal core 1 at the A-A' portions as shown in FIG.
A spiral electrode body is constructed using the unit electrode plates of the positive and negative electrodes after being cut. In FIG. 3, a positive electrode 3 and a negative electrode 4 are wound in a spiral with a separator 5 made of a nonwoven fabric made of polyamide resin interposed between the two electrodes, with their positions slightly shifted in the vertical direction from each other.This spiral electrode body A positive electrode current collector 6 made of a nickel-plated steel lath plate is mounted on the upper part (end surface of the positive electrode), and the current collector 6 and the upper edge of the positive electrode are welded at several locations. And the extension part 6' of the current collector is
It is welded to a metal sealing plate 8 that is electrically connected to a cap that also serves as a positive terminal. On the other hand, the lower edge of the negative electrode 4 is in direct contact with a current collector 10 similar to the positive electrode assembly disposed at the bottom of a bottomed metal container 9 which also serves as a negative electrode terminal. This negative electrode current collector can be partially welded to the bottom of the battery container in advance, or it can be press-inserted into the bottom of the battery container with an outer diameter slightly larger than the inner diameter of the battery container and placed between the bottom of the battery container. good. 12 is an elastic valve body, and 13 is a gasket.

Note that 1 and 5 are porous metal cores disposed inside the positive and negative electrodes, respectively. Figure 4 shows the discharge capacity when the 1.0Ah sealed nickel-cadmium storage battery made in this way was charged at a rate of 1 hour for 15 hours and then discharged at each discharge current. The curves are shown in FIG.

In Fig. 5 and Fig. 5, A is a product of the present invention, B is a battery constructed in the same way as the structure shown in Fig. 6, which is a general current collection method for secondary tanks, and C is a battery with a conventional core village exposed part. This is a battery that uses a tableless current collection method. As is clear from FIGS. 4 and 5, even if the discharge current becomes large, the discharge capacity and discharge voltage of the product of the present invention are lower than that of the conventional tableless method.
It is about the same level as B, and is clearly superior to B. The feature of the present invention is that the core material and the active material layer are exposed on the same surface and coexist, whereas in the conventional tableless current collection method, the current collector is welded to the exposed part of the core material at the edge of the electrode. The edge of the electrode in this state is either directly pressed against the inner bottom of the battery container or pressed against a negative electrode current collector spaced on the inner bottom of the battery container. A conductive portion between the current collector or battery container and the electrode is formed using the core metal as the main element and the active material as a secondary element. Generally, in the electrode edge, the core metal and the active material layer coexist on the same surface, and when a current collector is mounted on this part and welded together, if the electrode edge has poor electrical conductivity, welding Occasionally, sparks may occur, resulting in insufficient welding between the current collector and the metal core. The surface condition of the edge of the cadmium negative electrode differs between the sintered type and the base type. In other words, in the sintering method, a large amount of metal powder is bonded together, so the green conductivity of the cut end is relatively good, whereas in the paste method, conductive materials such as nickel are usually used to increase the capacity density. Because the amount of agent is small, it has poorer conductivity than the firing type. However, when charging the cadmium negative electrode, cadmium hydroxide converts into metal cadmium, which has good conductivity. Adequate physical contact is maintained. In particular, in a paste-type cadmium negative electrode, the method of the present invention is extremely effective when exposing the uncoated portion of the core metal as in the conventional tableless method would result in a large loss of core material. In the structure shown in FIG. 3, in order to maintain sufficient contact between the negative electrode and the current collector or the inner bottom of the battery container, the following measures may be taken for the negative electrode. In other words, by providing a negative electrode lead on the outermost periphery of the negative electrode and spot welding this negative electrode lead to the inner wall of the battery container, the position of the spiral electrode body within the battery container can be fixed, eliminating displacement and loosening, even if the battery Even if vibration is applied, the contact will not deteriorate. This negative electrode lead is not limited to the top of the outermost periphery, but can be taken out from the bottom of the outermost periphery or any position of the negative electrode that can protrude to the bottom, and fixed by welding or the like to the bottom of the battery container or onto the negative electrode current collector. It's okay.

In addition, in the above embodiment, the method of collecting current on the positive electrode side was shown as a method in which a current collector was layered on the positive edge and welded, but this positive edge and the current collector were fixed by a compression method. Various methods can also be explored, such as providing an exposed portion of the metal core on the edge, as in the conventional tableless type.

Therefore, in the present invention, in a spiral electrode body in which positive and negative electrodes are wound while being shifted vertically from each other, at least the electrode extreme green of the positive and negative electrodes coexists on the same surface with the porous core bar and the active material layer. state, and its negative edge may be pressed directly onto the inner bottom of the battery container or onto a negative electrode current collector fixed on the bottom of the battery container.
In the above embodiments, a paste type negative electrode was described, but a continuous type may also be used, and the core of the negative electrode may be in a continuous state instead of intermittently. Therefore, the battery system also has a structure in which a spiral electrode body other than the nickel-cadmium type of the embodiment is provided, and sufficient electrical contact is maintained by having at least the negative electrode side of the electrode edge in pressure contact with the battery container or the negative electrode current collector. It can also be applied to other battery systems.

In addition to the lath plate used in the examples, the current collector is preferably made of a material with burrs or irregularities such as net or punched metal, and is preferably made of a material that can sufficiently maintain contact with the end of the electrode core metal by pressure welding. . In addition, even if the material itself does not have unevenness,
For example, it is also possible to fix the ribbon-like material in the shape of a cross on the bottom of the battery container so that it is substantially uneven. Other effects of the present invention include the following.

Normally, unit electrode plates incorporated into batteries are industrially obtained by cutting large area electrode plates, but with the method of the present invention, the desired unit electrode plates can be obtained by simply cutting the unit electrode plates into required dimensions at the necessary locations. Since it does not require an exposed core metal part like the conventional tableless type electrode plate, it eliminates the complicated process of forming the core metal part when making electrodes of various sizes, increasing productivity and improving work efficiency. It can be done gracefully. As described above, the present invention achieves the following by improving the current collecting structure of the spiral electrode body.
This makes it possible to provide a battery that is inexpensive and has good strong discharge characteristics.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the end face of a negative electrode unit plate in a battery of the present invention, FIG. 2 is a diagram showing cutting when obtaining an intermittent porous core, and FIG. 3 is a diagram showing a battery in an embodiment of the present invention. FIG. 4 is a diagram showing discharge capacity characteristics, FIG. 5 is a diagram showing a discharge curve, and FIGS. 6 and 7 are half-cut side views showing conventional batteries. 1... Porous core metal, 2... Active material layer, 3...
...Positive electrode, 4...Negative electrode, 5...Separator "6...
... Positive electrode current collector, 8 ... Sealing board, 9 ... Bottomed metal container, I0 ... Current collector. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Scope of Claims] 1. A positive electrode and a negative electrode are vertically shifted from each other, and an electrode body is wound spirally with a separator interposed therebetween, and the positive electrode body is exposed at the upper and lower sides of the spiral electrode body. At least the end face of the negative electrode has the porous core metal and the active material layer exposed on the same surface, and this negative end face is directly on the bottom of the bottomed battery container or is fixed on the bottom of the container. A battery equipped with a spiral electrode body, characterized in that the spiral electrode body is pressure-welded onto a current collector. 2. A battery comprising a spiral electrode body according to claim 1, wherein the negative electrode is made of a paste-type electrode plate, and the exposed end surface thereof is made of an intermittent porous core bar and an active material layer. 3. A battery comprising a spiral electrode body according to claim 1, wherein the current collector is electrically connected to the bottom of the battery container by welding or pressing onto the bottom of the battery container. 4. A battery equipped with a spiral electrode body according to claim 1, wherein the negative electrode has a lead portion, and this lead is fixed to a battery container or a negative electrode current collector.