JPH0693364B2 - Thin secondary battery manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a thin secondary battery.

2. Description of the Related Art In recent years, electronic devices such as OA, AV / communication devices, etc.
With the increase in the density of circuits and mechanisms, pocket-type devices have come to appear, and in conjunction with this, secondary batteries that serve as power sources have also been stored in the device itself. The storage type includes a coin type, a square type (chewing gum type), and a card type (paper type), but the card type is promising in terms of storage efficiency. In order to reduce the thickness of the secondary battery into a card shape, the electrode plate, battery case, separator, etc. are formed thin and laminated (Fig. 4), or the electrode plate and separator are formed on the same plane, A structure (FIG. 6) in which the thickness of the sheet is reduced has been proposed.

Problems to be Solved by the Invention In the laminated type as shown in FIG. 4, since the facing area of the positive electrode plate 1 and the negative electrode plate 2 is large, the capacity can be secured, but when charged, it expands due to gas generation as shown in FIG. The separator 3 (nonwoven fabric containing glass fiber as a main component) is separated from the electrode plates 1 and 2 (peeling part 5), which leads to an early life. In order to prevent this, a pressurizing case is required, and since it becomes thicker by that amount, it is difficult to form a thin secondary battery.

On the other hand, when the positive electrode active material and the negative electrode active material are formed on the current collector 6 formed in the pattern of FIG. 6 to form the positive electrode plate 1 and the negative electrode plate 2, and the separator 3 is formed on the same plane between them. Eliminates the problem of peeling between the separator 3 and each of the electrode plates 1 and 2 due to gas generation and does not require pressurization, so that an extremely thin secondary battery can be formed. However, since the contact area between the positive electrode plate 1 and the negative electrode plate 2 facing the reaction and the contact area with the separator 3 is small, the capacity becomes small, which is not suitable for high rate discharge.

Means for Solving the Problems The present invention relates to a thin secondary battery in which one film-shaped battery case base is folded into two and the edges of the battery case base are joined to enclose a power generating element inside. In the manufacturing method, a metal is laminated on one surface and the other surface of the film-shaped battery case base, which are to be folded in half, to form a positive electrode current collector and a negative electrode current collector, respectively. A positive electrode active material pattern is formed on the positive electrode current collector, and a negative electrode active material pattern is formed on the negative electrode current collector to form a positive electrode plate and a negative electrode plate, respectively, and then, an electrolyte solution is formed on the positive electrode plate or the negative electrode plate. To form a separator or gel electrolyte, and then fold the film-like battery case substrate in two so that the positive electrode plate and the negative electrode plate are overlapped with each other through the separator or the gel electrolyte, and the edge of the battery case substrate is folded. Characterized by joining parts Is. In addition, additionally, the film-shaped battery case substrate has a mark for bending positioning or a bonding position mark, and the film-shaped battery case substrate is bent using this mark,
It is characterized by that. In this case, in order to ensure the capacity, the active materials of the positive electrode plate and the negative electrode plate are formed at the same position so as to face each other when folded, and the separator and the electrolyte are formed between both electrodes. On the other hand, when they were formed at different positions without facing each other, a separator or an electrolyte was formed between the upper part of the active material of the electrode plate and the active materials of both electrodes to increase the contact area or facing area between each electrode plate and the separator. At the time of bending and joining, there should be at least one or more fold-positioning marks, joining position marks, or fitting parts on the battery case base so that the positive and negative electrode plates will not be short-circuited so that they will be placed at the correct positions. Provided.

Example An example of the present invention will be described. Considering the case where the active material of the positive electrode plate 1 and the negative electrode plate 2 are at different positions when the battery case substrate 4 is bent, first, the active material of the positive electrode plate 1 and the negative electrode plate 2 formed in a comb-shaped pattern. As shown in FIG. 1, they are formed side by side on the current collector 6 on the film-like battery case base 4 made of synthetic resin. Then, on either one of the negative electrode plate 2 and the positive electrode plate 1, a separator or an electrolyte (for example, a gel electrolyte) that mainly contains glass fibers and holds an electrolytic solution is formed. Then, the battery case base 4 is bent so that the electrode plate is on the inside with AA ′ between the positive electrode plate 1 and the negative electrode plate 2 as a fold line, and the bonding position mark 8 is bonded by adhesion or welding. The peripheral portions of are joined. In this case, in the completed battery, one end of the battery case substrate 4 is bent and the other end is joined, as shown in the vertical cross section of FIG. Also,
As shown in the cross section of FIG. 2, the positive electrode active material and the negative electrode active material are formed at different positions in the vertical direction, but the separator 7 has a large contact area that wraps around the active materials of both electrodes, and also has a facing area. The number is larger than in the case of FIG. 6 in the same plane. The active material pattern may have a comb shape, a spiral shape, or a rectangular shape.

Using this battery, a 5-hour rate discharge (cut-off voltage 1.7V) and 2.45
A life cycle test was performed with constant voltage charging with a V-0.3C limited current. For comparison, the structure shown in FIG. 4 was used as the conventional product 1 and the structure shown in FIG. 6 was used as the conventional product 2. The life was determined when 50% of the initial capacity was cut off. From FIG. 7,
As described above, the conventional product 1 has a life due to early capacity deterioration due to the separation between the separator and each electrode plate. Conventional product 2
Has a life of 350 to 370 cycles, but the capacity is small from the beginning. On the other hand, the product of the present invention has a capacity as large as 1.3 times that of the conventional product 2, and has a life of 1.4 times that of 500 to 520 cycles.

EFFECTS OF THE INVENTION The present invention does not require the positive electrode and the negative electrode to be separately prepared and laminated together as in the conventional battery manufacturing method, and the positive electrode and the negative electrode are formed at once on the current collector integrated with the battery case. Since the separator or the electrolyte can be formed at the same time, the production line can be integrated continuously. Moreover, since only one battery case substrate is used, the material cost is reduced and no waste occurs. Further, since the alignment is also marked, the occurrence of defects is small and the industrial value is great.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of a thin secondary battery obtained by the embodiment of the present invention, FIG. 3 is a transverse sectional view of the same, and FIG. FIG. 5 is a vertical sectional view showing a conventional thin secondary battery, FIG. 5 is a vertical sectional view showing a state in which the structure of FIG. 4 is deformed during use, and FIG. 6 is another conventional thin secondary battery. FIG. 7 is a comparative curve diagram showing the results of the life cycle test. 1 is a positive electrode plate, 2 is a negative electrode plate, 3 is a separator, 4 is a battery case substrate, 5 is a stripped portion, 6 is a current collector, 7 is a separator, and 8 is a joining position mark.

Claims (2)

[Claims] 1. A method for manufacturing a thin secondary battery, comprising bending a single film-like battery case base into two, joining the edges of the battery case base, and enclosing a power generating element inside. A metal is laminated on one surface and the other surface of the film-shaped battery case base, which are to be folded in half, to form a positive electrode current collector and a negative electrode current collector, respectively, and then, on the positive electrode current collector. A positive electrode active material pattern is formed on the negative electrode current collector to form a negative electrode active material pattern as a positive electrode plate and a negative electrode plate, respectively, and then, a separator or gel for holding an electrolytic solution on the positive electrode plate or the negative electrode plate. Forming a cell-shaped electrolyte, and then folding the film-like battery case substrate in two so that the positive electrode plate and the negative electrode plate are overlapped with each other through the separator or the gel electrolyte, and joining the edges of the battery case substrate. And a method for manufacturing a thin secondary battery. 2. The film-like battery case base has a mark for bending positioning or a joining position mark, and the film-like battery case base is bent using this mark. Item 2. A method for manufacturing a thin secondary battery according to Item 1.