JPH04174958A - Manufacture of flat battery - Google Patents

Abstract

PURPOSE:To enhance the reliability of an IC card as a power source by pressing a sealing portion using a metallic band when welding the positive and negative electrode terminal assemblies of a battery to respective portions of a sealing plate, and passing current through the metallic band so as to weld each of the terminal assemblies to the sealing plate by means of heat generated at resistances. CONSTITUTION:A sealing member 4 comprising a polyethylene frame body is sandwiched between a positive electrode terminal assembly 5 and a negative electrode terminal assembly 6. A stainless metallic band 7 is pressed to the peripheral portion of the assembly 5 and currents are applied to both ends of the band 7. Next, the currents are cut off while the band 7 is being pressed. Ceramics is used for the fixing stand 8 of the band 7 and a Teflon sheet 9 is stuck to the surface of the band 7 so that the currents do not flow to the assembly 5 and then a battery is assembled. Thereby an IC card is used as a power source and the internal electrolyte is prevented from oozing to the outside even with loads exerted on the battery, thus providing a thin battery of high reliability for use in equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a flat battery that serves as a power source for thin devices such as IC cards and calculators. The present invention relates to a method for manufacturing a flat battery in which a power generation element is housed in a battery chamber formed by sealing by thermal welding with a sealing material made of a thermoplastic synthetic resin interposed therebetween.

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.
with intervening metal halide.

A sealing material 4 made of a thermoplastic resin such as polyethylene, polypropylene, Teflon, etc. is provided on the power generation elements of a positive electrode active material 2 made of metal oxide and a negative electrode active material 3 made of lithium,
The circumferential edges of the positive terminal plate 5, which is a stainless steel plate with a bulging central part or nickel plated on a stainless steel plate, and the negative terminal plate 6, which is a flat plate, are overlapped with the sealing material 4, and the sealing material 4 is 105 to 250 mm thick. It is manufactured by heating the power generation element at ℃ and thermally welding it to seal the opening. This thermal welding method involves embedding a rod-shaped heater 11 in a metal mold 10 (generally made of brass), keeping the metal mold 10 at a constant temperature by turning the heater ON and OFF, and using the heated metal mold 10 as a positive electrode. The terminal plate 5 or the peripheral edge of the negative terminal plate 6 is thermally welded by applying pressure, and the metal mold 10 is separated above the positive terminal plate 5 to cool and seal the opening.

This type of battery is required to have high reliability and long-term storage properties because it is used as a power source for IC cards and other memory storage.

Problems to be Solved by the Invention However, since this type of battery is used as a power source for the card, if you sit with the card in your back pocket of your pants, or if you drop the card and step on it, your weight will be applied to the battery. It's coming. When weight is applied to the battery, the electrolyte inside the battery leaks out from the welded portions of the positive and negative terminal plates and the sealing material, resulting in a decrease in battery capacity and damage to the circuit. This is because with conventional welding methods, the weld between the positive and negative terminal plates and the sealant is unstable, and when force is applied to the battery from the outside, the positive and negative terminal plates and the sealant have the weakest adhesive strength at the periphery of the seal. This is due to a phenomenon in which the electrolyte inside the battery leaks out from between the holes.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a method for heat-welding the peripheral edges of positive and negative terminal plates and the sealing material.
This problem can be solved by applying current to the metal band while applying pressure to the seal area, heating the sealing material using the heat generated by the resistance, and then cutting off the current to the metal band while applying pressure to cool the problem. .

Effect: By using the above manufacturing method, it is possible to stabilize the welding of the seal part.This is because in the conventional method, a rod-shaped heater 11 is embedded in the metal mold 10, and the heated metal mold 10 is connected to the positive terminal. When cooling the plate 5 or the peripheral edge of the negative terminal plate 6 by applying pressure and heat welding, the heated metal mold 10 must be released.In this state, the positive and negative terminal plates 5, 6
When the peripheral edge of the terminal plate and the sealing material 4 are heated under pressure,
The sealing material softens and melts when the parts are in close contact with each other. If the metal mold 10 is released and cooled in this state, the positive and negative electrode terminal plates 5 and 6 that were pressed during pressurization and heating will attempt to return to their original positions, and a portion of them will separate from the sealing material 4. When this portion was observed, a gap was found between the positive and negative terminal plates 5 and 6 and the sealing material 4. It is thought that the generation of this gap makes the welding force of the seal part unstable. However, in the present invention, when a metal band is applied to the peripheral edges of the positive and negative terminal plates 5 and 6 and a current is passed through the metal band under pressure, the metal band generates heat, and the sealing material 4
dissolve. Next, when the current is turned off with this sealing material melted, the temperature of the metal band decreases, and the sealing material is cooled and fixed to the positive and negative terminal plates 5 and 6 by welding. Therefore, if pressure is applied until the temperature of this metal strip falls, the positive and negative terminal plates 5
．． 6 did not move (stable welding was achieved, and the above problem was solved).

The present invention will be explained in detail below with reference to Examples.

Example FIG. 1 shows an embodiment of the present invention.

A negative electrode active material made of lithium is placed on a negative electrode terminal plate 6 made of a stainless steel plate. Separator made of polypropylene nonwoven fabric 1. Positive electrode active material using mankan dioxide as an active material 2. Positive electrode terminal plates 5 made of stainless steel plates with a bulging central portion are successively stacked one on top of the other. A sealing material 4 made of a polyethylene frame is sandwiched between the positive terminal plate 5 and the negative terminal plate 6. A metal band 7 made of stainless steel with a thickness of 0.1+nm and a width of 3 mm and a length of 40 wn is applied to the peripheral edge of this positive terminal plate, and a current is applied to both ends of the metal band 7. Next, the current to the metal band 7 is cut off while it is pressurized. The conditions were to apply a current of 40 amperes for 1.5 seconds, and then turn off the current for 4 seconds while pressurized. At this time, the temperature of the sealing material 4 changes as shown in FIG.

Ceramic is used as a fixing base 8 for the metal band 7 at this time, and a Teflon sheet 9 is pasted on the surface of the metal band 7. This Teflon sheet 9 prevents current from flowing to the positive terminal plate 5 when a current is passed through the metal band 7.

The battery assembled in this manner will be referred to as battery A.

Next, the battery material was constructed in the same manner as in Battery A, and the metal mold 10 was pressurized for 1.5 seconds with a rod-shaped heater 11 embedded in the peripheral edge of the positive terminal plate. After 4 seconds, the battery was removed. The battery assembled using this method was designated as Battery B. The temperature applied to the sealing material 4 of this battery B was 180° C., which is the same as that of the battery. Both batteries A and B had a size of 22 wn x 29 mm and a thickness of 0.5 mm.

A load test was conducted on these batteries A and B. The test conditions were to apply a load of 100 kg to the entire battery for 1 minute, and then observe whether the internal electrolyte came out. As a result, 10 batteries were tested for battery A, and none of them leaked electrolyte to the outside of the battery.

For battery B, 10 batteries were tested, and in 7 batteries, electrolyte came out outside the battery. Observing the seal part of battery B where the electrolyte came out outside of the battery, the state of the part where the electrolyte came out was originally sealed with the positive and negative terminal plates 5 and 6, which are the lower parts of the metal mold 10 when assembling the battery. Part of the part between materials 4 that should have been welded was not welded. Further, when observing the seal portion of battery A, it was found that the sealing material 4 and the positive/negative terminal plate 5.6, which is the lower part of the metal band 7, were completely welded together. This is because, as mentioned above, in Battery B, which welds the seal part using a metal mold embedded with a rod-shaped heater in the conventional method, it is not possible to cool the seal part while pressurizing it, so the terminal board is heated and welded. This is because the sealing material and the sealing material become separated. On the other hand, in the battery A of the present invention, by cooling for 4 seconds, the sealing part can be cooled while pressurizing to 50°C, which is below the softening point of the sealing material, about 110°C, thereby creating a stable and strong bond between the terminal plate and the sealing material. This makes possible welding.

Effects of the Invention For these reasons, the battery of the present invention can be used as a power source for an IC card, etc., and even if the battery is placed in the back pocket of pants or the like while sitting, or if the card is stepped on and weight is applied to it, the battery will remain intact. A highly reliable battery is obtained without any loss in performance, making it ideal as a power source for thin devices.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of the present invention, Fig. 2 is a sectional view showing an embodiment of a conventional battery, and Fig. 3 is a diagram showing temperature changes applied to the seal portion during welding in the embodiment. . 1...Separator, 2...Positive electrode active material, 3...Negative electrode active material, 4...Sealing material, 5...Positive electrode terminal Plate, 6...Negative terminal plate, 7...Metal band, 8...Fixing stand, 9
... Teflon sheet, 10 ... Metal mold, 11 ... Rod-shaped heater. Name of agent: Patent attorney Haruaki Ogata and 2 others 1-, t noji L-ta 2-sert; t#1 3-11 almost full-length Y 4--u・-16) Figure 1 5- y-sword on shoulder, 4-yar-1-ken chair j$4-kAf 8-fixed stand 9- Tefroso=,-1-

Claims (1)

[Claims] The positive and negative electrodes are placed between two sheet-shaped terminal plates that also serve as current collectors, with a separator interposed between them, and a window frame-shaped thermoplastic composite is placed between the peripheral edges of the sheet-shaped terminal plates. A method for manufacturing a battery in which the power generating element is sealed by thermally welding two terminal plates and the sealing material with a sealing material made of resin interposed therebetween, the method comprising: sealing the power generating element by thermally welding the two terminal plates and the sealing material, the method comprising: As a method for heat welding, the peripheral edge of the sheet-like terminal plate is pressurized with a metal band, a current is passed directly to the metal band, and the sealing material is heat welded by resistance heat generation, and then the metal band is A method for manufacturing a flat battery characterized by cutting off current to the battery and cooling it.