JPH0566707B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a method for manufacturing a thin battery. Specifically, a power generating element is covered with two upper and lower outer films, and the peripheral edges of the outer films are connected to each other through a frame-like frame. The present invention relates to a method of manufacturing a thin battery formed by bonding, which prevents a decrease in leakage resistance due to poor adhesion between an exterior film and a frame-like frame. <Prior art> As a manufacturing method for thin batteries such as thin alkaline batteries, neutral salt batteries, or lithium batteries, a positive electrode mixture and a negative electrode are laminated with a separator interposed between them. A current collector plate is brought into contact with each other on the other side, and the power generating element produced as described above is covered with two upper and lower exterior films, and then the peripheral edge of the exterior film is wrapped with a frame-like frame. A method is known in which the current collector plates are bonded together and sealed, and a part of the current collector plate is exposed through a window hole provided in the center of the outer film to be used as a positive terminal or a negative terminal. By the way, in such a manufacturing method, when bonding the outer film and the frame-like frame in the final process of the battery, by using a method of thermally fusing both under reduced pressure, the current collector plate and the positive electrode mixture are bonded together. Alternatively, attempts have been made to improve the adhesion with the negative electrode. <Problems to be Solved by the Invention> However, the above method has the following problems. That is, when the atmosphere of the battery is reduced in pressure prior to thermal fusion of the exterior film and the picture frame, the electrolyte contained in the positive electrode mixture, negative electrode, separator, etc. is degassed during the reduced pressure. As a result, it scatters and adheres to the adhesive surface between the exterior film and the picture frame. Due to the electrolytic solution present on the adhesive surface, the thermal adhesion between the exterior film and the frame-like frame becomes poor, and as a result, the sealing properties of the battery are impaired.
The leakage resistance of the battery will be extremely reduced. Also,
There is also the problem that the time-consuming work of heat-sealing the exterior film and the frame-like frame is performed under reduced pressure, which makes the work complicated and reduces work efficiency. <Means for Solving the Problems> The present invention provides a method for manufacturing a thin battery in which a power generation element is covered with two upper and lower outer films, and the peripheral edges of the outer films are connected to each other via a frame-like frame. In the method for manufacturing a thin battery formed by bonding, a through hole is provided in the side surface of a frame-like frame, and after the exterior film and the frame-like frame are adhered under normal pressure, the through hole is closed under reduced pressure. The gist is that. <Function> As described above, after bonding the exterior film and the frame-like frame under normal pressure, the battery is completed by using means to close the through holes provided on the side of the frame-like frame under reduced pressure. It is possible to prevent the electrolyte from adhering to the adhesive surface between the exterior film and the frame without impairing the adhesion between the current collector plate and the electrode mixture or the negative electrode. <Example> In FIG. 1 showing a thin alkaline battery,
1 is a separator made of a non-woven fabric made of an alkali-resistant material such as polypropylene; 2 is a positive electrode composite made of manganese dioxide and graphite; 3 is a gel-like negative electrode made of zinc powder, sodium polyacrylate, and potassium hydroxide solution; 4 is a positive electrode composite 5 is a positive electrode current collector plate made of iron foil plated with nickel and comes into contact with the agent 2; 5 is a negative electrode current collector plate made of copper foil that comes into contact with the negative electrode 3; 6,
7 is a current collector plate 4, 5 with epoxy resin adhesive etc.
An exterior film is made of a laminate film mainly made of plastic and is integrally bonded to the exterior film; 8 is a frame-like frame made of polyethylene that is adhered to the peripheral edges of the exterior films 6 and 7 by heat fusion. In addition, 4
a and 5a are a positive terminal and a negative terminal. A 35% potassium hydroxide solution is used as the electrolyte, and the positive bonding agent 2 and separator 1 are impregnated with the liquid. The frame-like frame 8 has the shape shown in FIGS. 2A and 2B, and has a small-diameter through hole 8a formed in its side surface. In addition, t1 to t4 are 24mm, 42mm, respectively.
2.5mm, 0.5mm. Such a picture frame-like frame 8
is combined with a power generating element consisting of a positive electrode mixture 2, a negative electrode 3, etc., which are encapsulated from above and below by exterior films 6, 7. It is heat-sealed using the method described below. Thin battery B made in this way is
As shown in FIG. 3, the fixing jig 10 is
Fixedly supported by. After the air in the decompression chamber 9 is sucked in the S direction and the thin battery B is placed in a depressurized atmosphere, the outside of the through hole 8a of the frame-like frame 8 is Part heating takes place. This heating causes the outer part of the through hole 8a to melt, and after cooling, the through hole 8a as shown in FIG.
a is in a closed state. In order to confirm the leakage resistance of the thus manufactured thin alkaline batteries (product of the present invention), 50 products of the present invention and conventional products were manufactured, and they were kept at a temperature of 60°C and a temperature of 90% for 10 days. and 30
The battery was stored for several days, and the number of leaking batteries at that time was determined. The results are summarized in Table 1.

[Table] Lower row: Number of tested batteries As is clear from Table 1, with the conventional product, out of 50 tested batteries, 4 leaked after 10 days of storage and 19 leaked after 30 days of storage. With the product of the present invention, out of 50 tested batteries, none leaked after 10 days of storage and only one leaked after 30 days, indicating that the present invention has significantly improved leakage resistance. I know that there is. <Effects of the Invention> As described above, the method for manufacturing a thin battery of the present invention is to close the through hole in the side surface of the frame under reduced pressure after adhering the exterior film and the frame under normal pressure. Therefore, it is possible to prevent the electrolyte from adhering to the bonding surface between the exterior film and the frame-like frame, and it is possible to reliably bond the exterior film and the frame-like frame. Therefore, the sealing properties of the battery can be improved and the leakage resistance can be improved, and as a result, the reliability of the battery is increased. In addition, in addition to providing a through hole in the frame-like frame, the battery is placed under reduced pressure after the above-mentioned adhesion is completed, and the through-hole in the frame-like frame is closed in this state, so the pressure inside the battery can be reliably and sufficiently reduced. can do. As a result, there is an advantage that the adhesion between the current collector plate and the positive binder or the negative electrode is significantly increased, and the battery discharge performance is improved. Furthermore, since the time-consuming process of adhering the exterior film and the frame-like frame can be carried out under normal pressure, which provides good workability, workability is improved and the battery can be manufactured more easily.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a thin battery manufactured by the method of the present invention, FIGS. 2A and B are a plan view and a sectional view showing a frame-like frame, and FIG. 3 is a frame-like frame. FIG. 3 is an explanatory diagram showing an example of a means for closing a through hole on a side surface. 2... Positive electrode mixture, 3... Negative electrode, 4, 5... Current collector plate, 6, 7... Exterior film, 8... Frame-shaped frame.

Claims (1)

[Claims] 1. In a method for manufacturing a thin battery in which a power generation element is covered with two upper and lower exterior films, and the peripheral edges of the exterior films are adhered to each other via a frame-like frame, the side surface of the frame-like frame is 1. A method for manufacturing a thin battery, comprising: providing a through hole in the battery, bonding the outer film and the frame-like frame under normal pressure, and then closing the through hole under reduced pressure.