JPS6121798Y2 - - Google Patents

Description

[Detailed explanation of the idea] This invention relates to a sealed battery.

Conventionally, as a sealed battery, for example, a flat silver oxide battery shown in FIG. A power generating element 2 consisting of a material 2a, a separator 2b and a cathode material 2c arranged in layers is loaded, and the inside of the battery case 1 is brought into contact with the anode material 2a so that the case 1 also serves as an anode terminal. The cathode material 2c is insulated and isolated from the battery case 1 by a dish-shaped electrically insulating packing 3 disposed along the inner surface of the battery case 1, and is further isolated from the battery case 1 by an open end 3a of the dish-shaped packing 3. Therefore, many batteries have been used in which the cathode side peripheral surface 2d of the separator 2b is pressed in an annular manner.

However, a considerable number of sealed batteries with this type of structure, especially those using metals such as Fe, Zn, and Li for the cathode, suffer from internal short circuits during long-term storage or charging. There are various possible causes for this internal short circuit, but the inventors have discovered that the main cause of this internal short circuit is that tendrites that occur during long-term storage or charging of the battery grow near the separator. However, it was found that this grown tendrite bridges the anode and cathode. Furthermore, according to what the present inventors have learned, the tendrite is composed of the separator 2b and the peripheral surface of this separator 2b.
It has been found that tendrite tends to grow at the interface with the open end 3a of the packing 3 that contacts the opening end 3a of the packing 3, or at the separator 2b in the vicinity, and tendrites that grow in these areas can cause internal short circuits in the battery due to long-term storage or charging. It was discovered that this was a major cause of the outbreak. Furthermore, in the sealed battery having the above-described structure, the open end 3a of the dish-shaped packing 3 presses the peripheral surface of the separator 2b. Because it is carried out through the department,
It was also found that the pressing force tends to be weak, and that this is related to the fact that when the case parts 2a and 2b are welded together, hot air blows from this welded part and has an adverse effect on the pressed part. Ta. In view of this, the inventors of the present invention have conducted various studies and found that, in a sealed battery having the above-mentioned configuration, from the peripheral surface of the separator on the anode side to beyond the outer peripheral edge of the separator. As described above, an annular insulating material layer having an L-shaped cross section is interposed along the corner portion spanning between the inside surface of the battery case on the cathode side, which also serves as an anode terminal, and the electrically insulating packing. It has been found that this method is particularly effective in preventing the occurrence of internal short circuits. This invention was made based on the above knowledge.

That is, the purpose of this invention is to prevent internal short-circuit accidents that may occur due to long-term storage or charging in a sealed battery configured as described above. Hereinafter, embodiments of this invention will be described in detail based on the drawings.

FIG. 2 shows an embodiment of a sealed battery according to this invention, in which a power generating element 5 is loaded into a metal battery case 4 consisting of a sealed metal case part 4a and a sealed metal case part 4b. ing. here,
The case 4 is made of iron plated with silver. Further, the power generation element 5 is constructed by laminating a separator 5b containing an electrolyte and a cathode material 5c on an anode material 5a solidified into a pellet shape. The cathode material 5c uses Fe, Zn, Li, etc. This cathode material 5c is electrically connected via a dish-shaped metal current collector plate 41 to a current collector rod 42 which also serves as a cathode terminal. On the other hand, the anode material 5a is
It is in direct contact with the inner surface of the case 4, which also serves as an anode terminal. In order to insulate and isolate the cathode material 5c from the case 4, the case 4,
In particular, a dish-shaped electrically insulating packing 6 is disposed along the inner surface of the sealing side case portion 4b, and the lower open end surface 6a of this packing 6 connects the upper peripheral edge of the anode material 5a to the separator. 5
It is pressed from above via the peripheral portion 5d of b.
Thereby, the cathode material 5c is isolated from the case 4 and the anode material 5a side by the packing 6 and separator 5b. Also,
The dish-shaped current collector plate 41 that is in contact with the cathode material 5c has its inner bottom side electrically welded to the inner end of the current collector rod 42, and its upper open end 41
a is abutting and pressing the packing 6 from the inside of the case 4, with part of the packing 6 biting into the packing 6. The current collector plate 41 is made of iron plated with silver, and is adapted to press the packing 6 by its elasticity. The current collector rod 42, which is welded to the current collector plate 41, is electrically insulated from the case 4 by a hermetic seal 43 made of glass or the like even when it passes through the center of the sealed case portion 4b. It is held while maintaining airtightness between it and the case 4.

With the above configuration, as shown in an enlarged view in FIG. 3, from the anode side peripheral surface 5e of the separator 5b, beyond the outer peripheral end 5f of the separator 5b, to the cathode side of the case 4. An insulating material layer 7 is interposed along the corner extending between the inner surface of the packing 6 and the outer surface of the packing 6. As a result, the joint part 8 between the separator 5b and the packing 6 and the part of the separator 5b in the vicinity thereof are surrounded by an annular insulating material layer 7 whose cross section is bent into a substantially L-shape, and tendrites grow in this part. However, this almost eliminates the possibility of forming an electrical path bridging the anode and cathode, ie, causing an internal short circuit. In the embodiment shown in FIG. 3, the insulating material layer 7 is composed of an insulating coating film. However, as shown in FIG. 4, this insulating material layer may also be formed of an insulating ring having an L-shaped cross section and pre-molded from a synthetic resin such as polyethylene.

FIG. 5 shows yet another embodiment of this invention. The difference from the above embodiment is that an outwardly inclined surface 9a is formed at the peripheral edge of the anode material 5a.
The open end surface of the dish-shaped packing 6 presses against the inclined surface 9a via the separator 5b, so that a component force acts in a direction that pushes the packing 6 outward. In this case, the insulating material layer 7 is annularly interposed along the acute angle formed between the anode-side peripheral surface 5e of the separator 5b and the cathode-side inner surface of the battery case 4. In the case of this embodiment, the vicinity of the opening end of the packing 6 is
Since the inclined surface 9a makes strong contact with the inner surface of the battery case 4, there is an advantage that the sealing condition around the insulating material layer 7 sandwiched therebetween is improved.

Now, the sealed battery configured as described above is designed to effectively prevent internal short circuits due to tendrites that occur during long-term storage or charging. The test results shown below are actual comparisons of the number of internal short circuits between sealed batteries A and B according to this invention and a conventional sealed battery C of the same type.

Here, battery A is based on the embodiment shown in FIGS. 2 and 3, and battery B is based on the embodiment shown in FIG. 4.

(1) Leave the battery at a temperature of 60℃ for 1 hour, then -10℃
The number of internal short circuits that occurred after 100 cycles of a temperature cycle test in which the product was left for one hour is shown below.

Batteries A 2 out of 100 Batteries B 1 out of 100 Batteries C 23 out of 100 (2) Discharge the batteries at 0.1°C and then charge them at a constant voltage of 1.8V for 24 hours. This was repeated for 50 cycles, and the number of batteries in which an internal short circuit phenomenon was observed during charging is shown below.

Battery A: 0 out of 20 batteries B: 1 out of 20 batteries C: 8 out of 20 As described above, the sealed battery according to this invention is
A power generating element consisting of an anode material, a separator, and a cathode material arranged in layers is loaded into a battery case formed by welding a bottom-side metal case part and a sealing-side metal case part to each other, and the inside of the battery case is The case also serves as an anode terminal by contacting the anode material of the power generation element, and the cathode material of the power generation element is connected to the cathode material of the power generation element by a dish-shaped electrically insulating packing disposed along the inner surface of the battery case. In a sealed battery which is insulated and isolated from the battery case, and in which the open end of the dish-shaped packing presses the peripheral surface of the separator on the cathode side,
An L-shaped cross section is formed along the corner extending from the anode side peripheral surface of the separator, beyond the outer peripheral end of the separator, and between the cathode side inner surface of the case and the outer surface of the packing. By interposing the annular insulating material layer, the occurrence of internal short circuits due to the formation of tend lines during long-term storage or charging is effectively prevented.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a conventional sealed battery, FIG. 2 is a sectional view showing an embodiment of the sealed battery according to the invention, and FIG. 3 is an enlarged sectional view of the main parts thereof.
FIG. 4 is an enlarged sectional view of main parts showing another embodiment, and FIG.
The figure is an enlarged sectional view of a main part showing still another embodiment. 1...Battery case, 5...Power generation element, 5a...
Anode material, 5b... Separator, 5c... Cathode material, 6... Packing, 7... Insulating material layer.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A power generation element in which an anode material, a separator, and a cathode material are arranged in layers in a battery case formed by welding a bottom side metal case part and a sealing side metal case part to each other. At the same time, the inside of the battery case is brought into contact with the anode material of the power generation element so that the case also serves as an anode terminal, and the cathode material of the power generation element is disposed along the inside surface of the battery case. In a sealed battery, the anode of the separator is insulated from the battery case by a dish-shaped electrically insulating packing, and the anode of the separator is pressed against the cathode-side peripheral surface of the separator by the open end of the dish-shaped packing. an annular insulating material layer having an L-shaped cross section extending from the side peripheral surface beyond the outer peripheral end of the separator and extending along a corner portion spanning between the cathode side inner surface of the case and the outer surface of the packing; A sealed battery with (2) The sealed battery according to claim 1, wherein the insulating material layer is a coating film. (3) The sealed battery according to claim 1, wherein the insulating material layer includes an insulating ring formed according to the shape of the corner portion.