JPH02177250A - Flat type call and manufacture thereof - Google Patents

Abstract

PURPOSE:To achieve high reliability even under the high temperature and high moisture by sealing both terminal strips of a positive electrode and a negative electrode by means thermal welding of a polymer frame, and after that, by sealing by means of thermal welding providing a polymeric fill frame on peripheral surfaces of outside the positive/negative electrode terminal strips. CONSTITUTION:On a separator 1 that is composed of a polypropylene non woven fabric in which an electrolyte including 1mol/l perchloric acid Li is permeated into a propylene carbonate as an organic solvent, a positive electrode active material of a sheet form in which kneaded Mn dioxide, C, and a binding agent is arranged, while under surface, a negative electrode active material 3 of Li is provided, and a central part is included with a positive electrode terminal strip 5 of stainless steel plate that is swelled outside and a negative electrode terminal strip 6 that is the same with the strip 5, and then, peripheries of positive/negative terminal strips 5, 6 are put together with the polypropylene frame 4 and the pressure of 180 deg.C, 3kg/cm<2> is applied to the both strips 5, 6 for pressure thermal welding. On the outer surfaces of the both strips 5, 6, polypropylene sheet frames 7 are provided and are pressure thermal welded to build a cell. Then, the frame 7 of the outer surface of each strip 5, 6 is pressure thermal welded using a polyethylene sheet frame.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to improvements in flat batteries that serve as power sources for thin devices such as IC cards and calculators.

BACKGROUND OF THE INVENTION As shown in FIG. 2, this type of battery has a separator 1 made of a polypropylene nonwoven fabric impregnated with an organic solvent electrolyte.
A polymer frame 4 made of polyethylene, polypropylene, Teflon, etc. is arranged on the power generation element of the positive electrode mixture 2 of metals, halogenides, and metal oxides, and the negative electrode active material 3 made of lithium. A positive terminal plate 6 made of a stainless steel plate with a protruding portion or a stainless steel plate plated with nickel, and a peripheral edge of a flat negative terminal plate 6 are overlapped with the polymer frame 4 to form 150 parts. ℃〜26
The power generation element is sealed by heating at 0°C and thermally welding. Since this type of battery is used as a memory retention power source for an IC card, there are many demands for high quality, particularly long-term reliability, and high performance characteristics.

Problem to be Solved by the Invention However, in this flat battery, since the distance between the electrodes at the outer periphery of the positive and negative terminal plates 5.6 is small, about 60 to 300 μm, conductive materials such as metal pieces adhere to the outer periphery. In this case, there was a problem that a short circuit occurred between the positive and negative terminal plates, resulting in a decrease in battery capacity.

Additionally, there is a problem in which the high temperature and high humidity storage test, which is a test for long-term reliability, is not satisfactory.

This test involves storing the battery in a 60'C90cm tank,
Judgment will be made based on the presence or absence of leakage and the rate of battery capacity deterioration. The storage period is generally 30 days, and it is assumed that there will be no leakage after storage. However, some conventional flat batteries leak.

As described above, conventional flat batteries have problems such as a decrease in capacity due to short circuits on the outer peripheral surfaces of the positive and negative electrode plates, and leakage during storage at high temperature and high humidity.

The present invention solves these problems.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides that after the positive and negative terminal plates 5 and 6 are sealed by heat welding with a polymer frame 4, the positive and negative terminal plates 5 and 6 are sealed.
A polymer film frame is provided on the outer peripheral surface of the negative electrode terminal plates 6, 6 and sealed by heat welding. Furthermore, compared to the polymer frame 4 between the positive and negative terminal plates 6, 6, the polymer film frame disposed on the outer peripheral surfaces of the positive and negative terminal plates 6, 6 is made of a material with a lower melting point. It is heat welded and sealed.

Function As described above, the battery of the present invention has a polymer frame disposed between the positive and negative terminal plates 6°6, and furthermore, the positive and negative electrodes! l@ Due to the configuration in which a polymer film frame is provided on the peripheral edge of the outer surface of the terminal board, positive,
The distance between the outer peripheral portions of the negative terminal plates 6, 6 is 1f1 or more, compared to 60 to 300 μm in conventional flat batteries. Therefore 1
In the battery of the present invention, even if metal pieces or the like adhere to the outer peripheries of the positive and negative terminal plates 6, 6, short circuits do not occur. Furthermore, when a high-temperature, high-humidity storage test was carried out, in a conventional flat battery, the organic solvent electrolyte gradually progressed from inside the battery to the interface between the positive terminal plate 5 or the negative terminal plate 6 and the polymer frame 4. ℃90
Leakage occurs when stored for 30 days. Further, when the leakage becomes large, a phenomenon occurs in which the interface between the terminal plate and the polymer frame 4 peels off. Also.

In this high-temperature, high-humidity storage test, flat batteries that are incorporated into thin devices such as IC cards must satisfy the L test even after the bending test.

However, when this bending test was conducted, force was applied to the interface between the terminal plate and the polymer frame 4, resulting in a decrease in adhesive strength, resulting in worse results than in a normal high-temperature, high-humidity storage test. The present invention solves this problem by greatly increasing the contact area between the positive and negative terminal plates 6, 8 and the polymer frame 4. If this method is adopted, by making the central part of the terminal board smaller than the position where it protrudes like a bulge, the reliability will be completely improved without affecting the thickness of the battery or reducing the battery capacity within the same volume. Can be done.

Furthermore, if the polymer frame 4 between the positive and negative terminal plates 6 and 6 and the polymer film frame disposed on the outer surface of the positive and negative terminal plates 6.6 are the same, the polymer film frame of the latter When heating and welding the former polymer frame 4 and the positive and negative terminal plates 6,
, 6 are reheated and become unstable. Further, in some cases, due to reheating, the positive terminal plate 5 and the negative terminal plate 6 come into contact, resulting in a short-circuit condition. This is more positive than the polymer frame 4 between the positive and negative terminal plates 5 and 6.

The above problem was solved by using a low melting point polymer film frame disposed on the outer surface of the negative electrode terminal plates 6, 6, without affecting the former polymer frame 4.

The present invention will be explained in detail below using examples.

Embodiment FIG. 1 shows a sectional view of an embodiment of the present invention. Manganese dioxide, carbon, and a binder were kneaded into a sheet shape on the upper surface of a separator 1 made of a polypropylene nonwoven fabric with a dark electrolyte solution containing 1 mol/l of lithium perchlorate in propylene carbonate as an organic solvent. Positive electrode active material 2
A negative electrode active material 3 made of lithium is provided on the lower surface, and a positive electrode terminal plate 6 made of a stainless steel plate with a central portion bulged outward, and a negative electrode terminal plate 6 similar to the positive electrode terminal plate 6 described above are included. Then, the peripheral edges of the positive terminal plate 6 and the negative terminal plate 6 were overlapped with the polypropylene frame 4, and a pressure of 3 kg/C- was applied to the positive terminal plate 6 and the negative terminal plate 6 at 180°C. Heat welded.

Next, a polypropylene sheet frame 7 is placed on the outer surface of the positive and negative terminal plates 6 and 6, and the polypropylene sheet frame 70 is welded under pressure and heat at 180° C. and 3 Kf/i to complete the battery. Assembled. The width of the polypropylene frame 4 at this time is 1.8 ff, and the polypropylene sheet frame 7
The width of is set to 2H.

Next, a polyethylene sheet frame was heat-welded to the polypropylene sheet frame 7 placed on the outer surface of the positive and negative terminal plates 5.6 at 160° C. by applying a pressure of 3 kg/-. Assembled the battery.

Next, as a conventional example, as shown in Fig. 2, a positive electrode mixture sheet 2 is placed on two sides of a separator 1 made of a polypropylene nonwoven fabric impregnated with an electrolytic solution, and a negative electrode active material 3 made of lithium is placed on the bottom side. and a positive terminal plate 6 made of a stainless steel plate and a negative terminal plate 6 made of a stainless steel plate with a protruding central portion.
and 180°C in the same manner as in the embodiments of the present invention.
The battery was assembled by heat welding by applying a pressure of 3 K7/ca.

The dimension of the polypropylene frame 4 at this time was set to 2ff.

The above conventional battery is considered as a battery person, and the battery of the present invention is positive.

A battery B used a polypropylene sheet frame for the polymer film frame 7 disposed on the outer surface of the negative electrode terminal plates 5 and 6, and a battery C used a polyethylene sheet frame. All of these batteries have a battery size of 16 fl x 3.
It was set to 4 fl and a thickness of 0.5 H.

Further, the thickness of the polymer frame 4 is 100 μm.

The thickness of the polymer film frame 7 was 70 μm.

A high temperature and high humidity test was conducted on each of the above batteries.

The test conditions were that the batteries were stored at 90°C and each battery was checked for leakage, and the battery capacity after storage was checked.

Table 1 shows the number of leaks when 10 batteries were stored.

(The following is a margin.) Next, the stored battery 1- was discharged at a constant resistance of 68Ω, and the discharge capacity of the stored battery n1 was set to 100, and the discharge maintenance after storage is shown in Table 2. The numbers in the table are the average values of three.

Table 2 Unit: Jinji Next, a bending test was conducted on the batteries A, B, and C, and after the bending test, a high temperature and high humidity storage test was conducted. The test consisted of a bending test in which batteries A, B, and C were alternately aligned and separated from a sphere with a radius of 90R 500 times, and each battery was stored at 60°C and 90% to prevent leakage. The liquid state and discharge maintenance rate were confirmed. The results are shown in Tables 3 and 4.

(Margin below) From the above results, with conventional battery packs, some batteries leak after being stored for 2Q days. However, one invention batteries B and C are 4
Can withstand 0 days or more. In addition, the battery of the present invention showed better results in terms of discharge maintenance rate than the conventional battery.

Table 4 Unit: From the test results above, conventional batteries cannot meet the general requirement of storage at 60°C, 90% for 30 days in a high temperature and high humidity storage test. In addition, in the high temperature and high humidity storage test after the bending test in the latter test, 30 days of storage resulted in
% leakage occurred. - Rikiki's invented batteries B and C showed satisfactory results with no leakage after storage at 60° C. and 90° C. for 30 days in both tests. Another invention battery B.

Comparing C, it was found that battery C of the present invention was able to improve reliability compared to the battery of the present invention.

Furthermore, although a polypropylene frame was used here as the polymer frame 4 between the positive and negative terminal plates 6 and 6, similar results can be obtained with polyethylene or Teflon frames. In addition, in the battery C of the present invention in the example, a polypropylene frame was used for the polymer frame 4 and a polyethylene film frame was used for the polymer film frame 7, but compared to the polymer frame 4, the polymer frame Similar characteristic results can be obtained if the frame 7 has a lower melting point. However, as the polymer film frame 7,
A polyethylene sheet frame that can be welded at low temperatures and has strong adhesive strength is ideal for improving productivity because it can be easily welded and the welding speed can be increased.

The polymer film frame 7 can be formed by dissolving a polymer in a solvent and applying it to the outer surfaces of the positive and negative terminal plates 6, 6, or by spraying. If a method is adopted in which a polymer film frame previously formed into a sheet is placed on the outer surface of the positive and negative terminal boards and heat welded, the polymer film frame can be formed uniformly and is suitable for Ti properties. .

In addition, in conventional batteries, the distance between the positive and negative terminal plates 6 and 6 is 1
There were batteries as small as 00 μm that caused a short circuit when they came into contact with the metal plate after battery assembly, but 1 invention battery B.

In C, there was no short circuit because the battery was separated by 4fl on the outer periphery.

Effects of the Invention For these reasons, the battery of the present invention does not cause short circuit after battery assembly and has high reliability even when stored at high temperature and high humidity, making it optimal as a power source for thin devices.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the assembly process of a battery according to an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional battery. 1... Separator, 2... Positive electrode active material, 3... Negative electrode active material, 4... Polymer frame, 6... Positive electrode terminal plate, 6... Negative electrode terminal plate, 7... Polymer film frame.

Claims (3)

[Claims] (1) A power generation element in which a separator is interposed between the positive electrode mixture and the negative electrode active material, and a positive and negative electrode in which a polymer frame is arranged around the periphery of this power generation element, and at least one central portion bulges outward. A flat battery in which the above-mentioned power generating element is enclosed in a terminal plate and sealed by providing a polymer film frame on the outer peripheral surfaces of the positive and negative terminal plates. (2) The polymer film frame disposed on the outer peripheral surface of the positive and negative terminal plates has a lower melting point than the polymer frame between the positive and negative terminal plates. The flat battery according to item 1. (3) A positive electrode mixture and a negative electrode active material are provided on the upper and lower surfaces of the separator, and these are surrounded by positive and negative electrode terminal plates with at least one center part bulging outward, and between the positive and negative electrode terminal plates. A polymer frame is provided on the periphery, and the peripheral edges of the positive and negative terminal plates are sealed by heat welding.A polymer film frame is provided on the outer peripheral surface of the positive and negative terminal plates, and the polymer film frame is A method of manufacturing a flat battery characterized by assembling a film frame and positive and negative terminal plates by bonding them together by heat welding.