JPS6041827B2 - Button battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a button type battery used in fields such as electronic wristwatches, cameras, electronic desktop calculators, and hearing aids.

This type of button-type battery uses Ag as the positive electrode.

O) Ag2O2, MnO2, etc., gelled Zn on the negative electrode,
In addition to alkaline batteries that use an aqueous KOH)NaOH solution as the electrolyte, (CF)nNMnO is used as the positive electrode. etc., l■L
−に'−ーi■ ゛ Bottom Γmta,, 0-1-0”l
, ′ − ゛→−Re There is a non-aqueous battery with so-called high energy density that uses an inorganic salt dissolved in an organic solvent such as γ-butyrolactone. However, in either case, a current collector is spot welded to the inner bottom of the metal case that is open at the top, a pellet-shaped positive electrode mixture is crimped onto it, and then the outer periphery of the molded positive electrode mixture is attached to prevent internal short circuits. After inserting the metal positive electrode ring, stack the separator member impregnated with electrolyte, the negative electrode active material, etc. on the molded positive electrode mixture in order, and arrange them so that they are all in contact with each other. The opening end of the metal case is covered with a metal sealing plate via the provided annular sealing packing, and the opening edge of the metal case is curved inward for sealing.
The button-type battery having such a conventional structure has the following drawbacks.

In other words, 1 Generally, when assembling a battery, it weighs several tens to several 100 kg.
Since the metal positive electrode ring must be able to withstand the outward stress applied at that time, there is a limit to how thin it can be.
The decrease in effective capacity was seen as a problem. 2 When assembling the metal sealing plate over the molded cathode mixture, the separator member placed on the molded positive electrode mixture could become misaligned due to entrainment, which could cause an internal short circuit. Despite this, there were many defective products. 3. Due to the pressure applied during assembly, the electrolyte contained in the separator member escapes to the outside, resulting in a decrease in utilization due to an absolute lack of electrolyte, or leakage between the sealing plate and sealing backing during battery storage or discharge. The electrolyte leaked to the outside along the route, reducing the utilization rate.

The purpose of this invention is to improve the above-mentioned drawbacks. The first aspect of the present invention is that at least the outer edge portion of the upper end surface of the outer cylindrical surface and end surface of the molded positive electrode mixture is covered with a heat-shrinkable synthetic resin film.
The second invention covers at least the outer edge portion of the upper end surface of the outer cylindrical surface and end surfaces of a stacked product of a molded positive electrode mixture and a separator member with a heat-shrinkable synthetic resin film.

This invention will be explained with reference to the embodiments shown in the drawings. In FIG. 1 showing the first embodiment of the invention,
Inside a cylindrical metal case 1 with a current collector 8 spot welded to its inner bottom surface and open at the top, there is a molded positive electrode mixture 2 that is in good contact with the current collector 8 .

As shown in FIG. 2, the outer rim portion of the upper end surface of the molded positive electrode mixture 2 is covered with a heat-shrinkable synthetic resin film 4. As shown in FIG. The thickness of the film 4 may be very thin, on the order of several tens of microns, and is extremely thin compared to conventional metal positive electrode rings, and has no electrical conductivity. Therefore, a separator member 3 that has absorbed a predetermined amount of electrolyte is placed on the shaped positive electrode mixture 2, and an annular seal is placed so that it is in contact with the outer cylindrical surface covered with the film 4 of the shaped positive electrode mixture 2. Insert backing 5. Then, the current collector 7 is spot welded to the inner bottom surface of the metal sealing plate 6, and the negative electrode active material 9 that has made good contact with the current collector 7 is covered so as to overlap the separator member 3, and then the metal When using a sealed button-type battery as shown in Fig. 1 with the opening edge of case 1 curved inward, one!
It can produce a similar effect. First, since there is no metal positive electrode ring, and instead there is a coating layer made of a very thin heat-shrinkable synthetic resin film 4, this is extremely effective in improving the effective volume of a small battery.

In addition, this film 4 covering layer does not tear or cause any inconvenience when subjected to vertical pressure of several 10 to several 100 k91 d during battery assembly, and even if the separator member 3 is slightly displaced during assembly. As mentioned above, since the outer edge portion of the upper end face is covered with the film 4, there is no particular problem, and the drawback of internal short circuit is greatly improved. Next, referring to FIG. 3 showing an embodiment of the second invention of the present invention, what is different from FIG. The difference is that the outer rim portion of the upper end surface of the outer cylindrical surface and end surface of the included stacked products is covered with a heat-shrinkable synthetic resin film 4 (see FIG. 4). The covering may have an inverted L-shaped cross section as shown in FIG. 4, or a U-shaped cross section as shown in FIG. 5. It is easier to work with an inverted L-shaped S-shaped cross section. The expected effects of the second invention described above are that since the separator member 3 is integrated with the molded positive electrode mixture 2, the possibility of misalignment during assembly is completely eliminated, and the separator member 3 is not only formed on the outer cylinder surface but also on the outer cylinder surface. Since at least the outer edge portion of the upper end face of the end face is covered with the film 4, leakage of the retained electrolyte to the outside due to the separator member 3 being pressed during assembly is minimized.

Furthermore, while the battery is stored at high temperatures, the electrolyte permeates into the internal voids of the molded positive electrode mixture 2 and the volume of the molded positive electrode mixture 2 expands.
If the film 4 of the present invention covers not only the outer cylindrical surface but also at least the outer edge portion of the upper end surface of the end surface, the expansion will only occur in the center, and the entire surface will not swell. As a result, the electrolytic solution held in the separator member 3 is pushed out by the pressure on the separator member 3 due to the volume expansion of the molded positive electrode mixture 2 and moves into the void inside the battery, and the pushed out electrolytic solution The leakage of liquid to the outside has been greatly improved, and leakage to the outside has been eliminated in a short period of time. Now, the button type battery in Figure 3 is A1, the button type battery in Figure 1 is B1, number 5
The button type battery with the positive electrode part shown in the figure is designated as C, and for comparison, a button type battery with a conventional metal positive electrode ring is designated as D1.The button type battery that does not even have a metal positive electrode ring is designated as E. When the constant current discharge characteristics immediately after and after one month of high temperature storage were tested, the results shown in FIGS. 6 and 7 were obtained.

What can be seen from Figure 6 is that all batteries start discharging from 3.3V and gradually decrease to 2.75V after 2 hours.
V, and maintained an almost flat potential of 2.6 V even at the end of discharge, but battery E had the best discharge utilization rate at 95%, followed by batteries A, B, and C at 93%, and battery had the lowest. D
It was 90% of the time.

In Figure 7, which shows the 1 mA constant current discharge characteristic results after 600C storage for 1 month, battery E has severe leakage to the outside, with almost no electrolyte retained in the separator member, and the internal resistance increases, resulting in flat areas. 5 hours after the start of discharge, the final voltage was dropped.

On the other hand, batteries A and C maintained an almost flat potential of 2.6 V to 2.4 V, and had a good discharge utilization rate of 90%. Remaining battery B (usage rate with 5D is 85%)
, it had dropped to 80%. The reason for this seems to be that the electrolytic solution held by the separator member has begun to dissipate to the outside, and the absolute amount of electrolytic solution involved in discharge has become insufficient. The number of occurrences of internal short circuits and the number of external leakages during high temperature storage were investigated, and the results shown in Tables 1 and 2, respectively, were obtained.

In this way, the button type battery having the configuration of this invention is
It is sufficient to achieve the intended purpose.

[Brief explanation of drawings]

1 and 3 are cross-sectional views of a button-type battery according to the present invention, FIGS. 2 and 4 are cross-sectional views of the positive electrode portion of FIGS. 1 and 3, respectively, and FIG. 5 is a cross-sectional view of another example. FIG. 6 is a cross-sectional view of the positive electrode portion shown, and FIG. 6 is a diagram showing the results of constant current discharge characteristics of 17T1 and A after storage at 60° C. for one month, respectively. DESCRIPTION OF SYMBOLS 1... Metal case, 2... Molded positive electrode mixture, 3... Separator member, 4... Heat-shrinkable synthetic resin film, 5... ...Annular sealing backing, 6...Metal sealing plate, 9...Negative electrode active material.

Claims (1)

[Claims] 1. A molded positive electrode mixture 2, a separator member 3, and a negative electrode active material 9 are stacked and packed in order between a metal case 1 and a metal sealing plate 6, and are sealed via an annular sealing packing 5. A button type battery characterized in that at least the outer edge portion of the upper end surface of the outer cylindrical surface and end surfaces of the molded positive electrode mixture 2 is covered with a heat-shrinkable synthetic resin film 4. 2. In a button type battery in which a molded positive electrode mixture 2, a separator member 3, and a negative electrode active material 9 are sequentially stacked and packed between a metal case 1 and a metal sealing plate 6 and sealed via an annular sealing packing 5, the molding is performed. A button-type battery characterized in that at least the outer line portion of the upper end surface of the outer cylindrical surface and end surfaces of a stacked product of a positive electrode mixture 2 and a separator member 3 is covered with a heat-shrinkable synthetic resin film 4.