JPS6138582B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an improvement in the sealing method for the peripheral gap of a thin battery, and involves applying heat to the peripheral gap between an anode metal current collector plate and a cathode metal current collector plate covered with a conductive plastic film. A sealing material made of meltable synthetic resin is interposed,
The purpose of this invention is to apply ultrasonic vibration to the peripheral edge of the current collector plate under reduced pressure to heat-fuse the current collector plate to form a good seal, prevent external leakage of electrolyte, and improve battery storage performance. [Prior art] Conventionally, thin batteries have been manufactured by interposing a separator between the anode body and the cathode body, the peripheral edge of which is impregnated with a heat-melting resin, and then sealing the battery periphery to the outside of the battery using an electric iron for heat sealing. They were sealed and fixed by heat-pressing with a hot roller or by heat-pressing with a hot roller. [Problems to be Solved by the Invention] However, with the conventional sealing method, in the case of a single-layer battery, heat is transferred by heating and pressing the periphery, and the air inside the battery expands rapidly, creating an escape route for the battery internal pressure in the periphery gap. There were some areas where the seal could be lowered, which caused leakage due to insufficient sealing. In the case of stacked batteries, the batteries at both ends are overheated, and the batteries in the center are underheated, resulting in insufficient sealing, which can cause leakage and dryness inside the battery after long-term storage. Ta. In addition, if heat and pressure are applied for a long time to sufficiently seal the middle battery, the batteries at both ends of the battery will be heated excessively, which may melt the conductive plastic film or tear the separator, causing internal shortening. A problem arose. Additionally, as described in Japanese Patent Publication No. 52-306955, there was a method for manufacturing batteries in which a pressure-sensitive adhesive was applied to the periphery of a thin battery in an unsealed battery, and the periphery was sealed under reduced pressure. . However, although the air inside the battery is removed by reducing the pressure, internal parts of the battery become obstacles, and some independent air bubbles are unable to move, or surface tension does not allow them to move through narrow gaps. In some cases, the air inside the battery could not be completely removed. In addition, the pressure-sensitive adhesives used are heat-sensitive adhesives that are sticky at high temperatures and lose their stickiness at room temperature, and solvent-based adhesives that are made sticky by a solvent and bond by volatilizing the solvent. Pressure-sensitive adhesives have different properties, as they stick with pressure, so they are always viscous and their viscosity may decrease as the temperature rises in summer, causing the adhesive to shift or come off, making it difficult to seal thin batteries. There were problems such as performance deterioration. The present invention was made to solve the above-mentioned problems, and its purpose is to apply ultrasonic waves to a thin battery under reduced pressure to seal the periphery of the battery, thereby improving leakage resistance and storage performance. shall be. [Means for Solving the Problems] The present invention comprises sandwiching a battery power generation element in which an anode body, a cathode body, and a separator are stacked between metal current collector plates coated with a conductive plastic film, and applying heat to the space between the peripheral edges. After filling the sealing material made of meltable synthetic resin and inserting the battery into a vacuum bag and expelling the air inside the bag,
Under reduced pressure, the periphery of the battery is pressurized from outside the bag with a vibration transmission gun while applying ultrasonic vibrations, causing molecules to vibrate at the interface between the sealing material and the conductive plastic film, generating heat due to friction between the molecules. It is fused to seal the battery peripheral gap. In addition, in the case of a laminated battery, an anode body is formed on one side of a metal current collector plate whose circumferential surface is coated with a conductive plastic film, and a cathode body is formed on the other side. There are products that seal using ultrasonic waves. [Function] The present invention involves inserting a battery into a vacuum bag, expelling air,
Since ultrasonic vibrations are applied under reduced pressure, air does not accumulate inside the battery, no air insulators are formed within the battery, and the electrical conductivity of the periphery is improved without causing heat damage to the power generation element. The plastic film and the sealant can be fused only at the interface, improving the battery's leakage resistance, discharge performance, and storage performance. [Example] Below, thin batteries according to examples of the present invention are shown in Figures 1 and 2.
This will be explained with reference to FIGS. In FIGS. 1 and 2, 1 is a cathode current collector plate, and 2 is an anode current collector plate. The bipolar current collector plates 1 and 2 are made of corrosion-resistant metal foil such as aluminum, nickel, steel, stainless steel, etc., and the inner surfaces are coated or sprayed with carbonaceous material added with a binder such as polyvinyl chloride resin. A conductive plastic film 3 is attached by attaching or the like. Reference numeral 4 denotes a thin layered cathode body made of a cathode active material such as zinc foil or zinc powder, which is adhered to the conductive plastic film 3 of the cathode current collector plate 1 . 5 is, for example, an anode body mainly composed of manganese dioxide powder as an active material, and acetylene black as a conductive material, and polyvinyl alcohol or polyacrylic acid as a binder. The conductive plastic film 3 of the anode current collector plate 2 is adhered to the plastic film 3 in a thin layer by, for example, screen printing or roller coating. This cathode body 4
A separator 6 made of a nonwoven fabric of acetalized polyvinyl alcohol fibers is sandwiched between the anode body 5 and the anode body 5 . The separator 6 contains an electrolytic solution consisting of, for example, a zinc chloride aqueous solution or a mixed aqueous solution of zinc chloride and ammonium chloride. Further, the periphery of the separator 6 is impregnated with an adhesive 7 mainly made of polyamide resin, for example, to prevent the electrolyte from leaking from the periphery of the separator 6. Reference numeral 8 denotes a sealing material held between the peripheral edge spacing portions 9 of the bipolar current collector plates 1 and 2, and is made of, for example, saturated polyester resin or polyamide resin. Next, the sealing material 8 is fused to the conductive plastic film 3 while applying ultrasonic vibration from the outside of the decompression bag 14 in a reduced pressure state, and the bipolar current collectors 1 and 2, the negative and anode bodies 4 and 5, and Battery power generation elements such as the separator 6 are stacked and sealed to produce a thin battery. The sealing material 8 and the conductive plastic film 3
The fusion is performed as follows. As shown in FIG. 3, a thin battery is inserted through the opening into an envelope-shaped decompression bag 14 made of flexible rubber made of polytetrafluoroethylene, etc., and which has an opening on one side. Insert the battery into a U-shaped frame whose inner diameter is slightly smaller than the inner diameter of the decompression bag 14 and whose inner width is equal to the width of the battery, and insert the battery together with the frame into the decompression bag 14.
Gently pinch the battery and remove only the frame. Next, the opening of the pressure reducing bag 14 is stretched and connected to the elongated suction hole 10 of the pressure reducing device 13 so as to cover it, and the internal pressure is reduced by suction to 300 to 700 mmHg. During suction, the opening of the bag 14 is pressed down by external pressure.
It never goes away. For positioning, the vacuum bag 14 is made of rubber and has flexibility, so the bag 1 is positioned by suction.
The upper and lower surfaces of 4 are in close contact with each other and are thin, and only the part where the battery is present is thick and can be visually aligned with the pedestal 12.
Since the pedestal 12 and the vibration transmission horn 11 are fixed as a pair, positioning can be performed simply by aligning them with the pedestal 12. Next, the pressure reducing bag 14 containing the thin battery is reduced to 300 to 700 mmHg from the suction hole 10 using the pressure reducing device 13, and for example, with an output of 1200 W and an oscillation frequency of 19 KHz,
The periphery of the thin battery is pressurized with a pressure of 14 kg/cm ² using the vibration transmission horn 11 manufactured by Duralun, an ultrasonic welder, and ultrasonic vibrations are oscillated for 3 seconds to generate heat, causing the heat-melting synthetic resin to reach the interface. Dissolves uniformly and seals completely. To remove the thin battery, air is flowed back from the decompression device 13 and the decompression bag 1 is removed.
4, and remove it from the suction hole 10.
A sealed thin battery "A" that has been ultrasonically fused is taken out from the envelope-shaped bag. The depressurizing bag 14 stores an unsealed thin battery inside and removes air from inside the battery by discharging air from the suction hole 10. Even if the battery is compressed due to external pressure, the sealing material 8 will not melt. Because it uses synthetic resin,
Since there is no heat generation, the sealing material will not fuse. Therefore, the air inside the battery is discharged from the battery peripheral spacing section 9. After being discharged, ultrasonic waves are applied to generate heat due to intermolecular friction to fuse the battery periphery gap 9. In addition, since the decompression bag 14 is used, there is no need to create a depressurized atmosphere in the entire sealing device in order to remove air that acts as an insulator when present inside the battery, and only needs to be done inside the bag, which simplifies the equipment. , it becomes advantageous in terms of labor, time, and cost. Furthermore, since the heat-melting synthetic resin is interposed only in the peripheral gap 9 of the bipolar current collector plate, when heat is generated by the ultrasonic vibration transmission horn 11, only the heat-melting synthetic resin melts, and the bipolar collector plate Only the peripheral gap 9 of the electric plate is sealed, and the decompression bag 14, which does not contain heat-melting synthetic resin, is not fused to the battery. Therefore, there is no problem in taking the battery in and out of the decompression bag 14. In the thin battery according to the present invention, ultrasonic energy is applied only to the battery periphery for the purpose of fusion, and the conductive plastic film 3 is also applied in the thickness direction.
Since the sealing material 8 is positioned at the boundary between the sealing material 8 and the sealing material 8, and ultrasonic heat is generated from the inside to fuse the sealing material, the speed required for the welding is extremely faster than conventional heat-sealing using an electric iron or heat roller. Even after fusion, cooling time is required for the battery to solidify, and since the power generating elements are uniformly and completely fused, there is no deterioration or deformation, so there is no fusion failure, and the battery's leakage resistance and storage properties are improved. . Next, the battery according to the embodiment of the present invention and the battery manufactured by the conventional method were separated into a battery having a width of 40 mm and a length of 70 mm.
Compare with a 1.5V thin battery with a thickness of 200mm. The present invention product "A" is different from the conventional product "B" under the above conditions.
is a vacuum packaging machine using an impulse heater.
This is a thin battery manufactured by reducing the pressure to 700 mmHg and pressing a heater with a heater surface temperature of 180° C. at a pressure of 18 Kg/cm ^{2 ,} heating for 5 seconds and cooling for 10 seconds to fix the battery. The above-mentioned batteries [A] and [B] were evaluated based on the incidence of defective batteries that leaked due to poor fusion, the discharge duration up to 0.9V with a 1000Ω constant resistance discharge immediately after manufacture, and the 45
The following table summarizes the average value of each 10 samples and the discharge duration under the same conditions after storage at ℃ for 3 months.

[Table] [Effects of the Invention] As described above, the present invention improves the sealing performance and storage performance of a thin battery.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a thin battery according to the present invention, Figure 2 is a cross-sectional view of a thin battery according to the present invention;
The figure is a sectional view of a laminated thin battery according to another embodiment of the present invention, and FIG. 3 is an explanatory view of a sealing device used in the method of the present invention. 3... Conductive plastic film, 8... Sealing material, 9... Peripheral spacing, 10... Suction hole, 11... Vibration transmission horn, 12... Pedestal, 13... Pressure reducing device, 14
...Bag for decompression.

Claims (1)

[Claims] 1. A sealing material made of a heat-melting synthetic resin is applied to the periphery of the metal current collector plate, which is formed by applying a conductive plastic film to the surface of the metal current collector plate that faces the battery power generation element and sandwiching the battery power generation element. After inserting the battery filled with the battery into a depressurizing bag and expelling the air inside the bag, ultrasonic vibrations are applied to the periphery of the battery from outside the bag in a depressurized state to heat-fuse the sealing material and the conductive plastic film. 1. A method for manufacturing a thin battery, comprising: sealing a peripheral gap.