JPH0963550A - Battery - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a battery that is excellent in flexibility and moisture resistance, and that is highly sealed even when external stress is applied. SOLUTION: Electrodes 1 and 5 and electrolyte substances 2 and 5 are provided in battery casing materials 7A and 7C made of a multilayer film in which fusible resin layers 9A and 9C are coated on both surfaces of conductive plates 8A and 8C.
A battery containing the above-mentioned battery exterior material 7A,
The lead portions 10A and 10
By heat-sealing C, 11A and 11C, the conductive plate 8A,
8C, and electrodes 1 and 5 are further connected to inner lead portions 10A and 10C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery suitable as a power source for thin electronic devices such as IC cards.

[0002]

2. Description of the Related Art For example, in an IC card, a power source is built in the card body to hold the stored information. The power supply built into this IC card must meet the following requirements.

First, with regard to the size of the IC card, JI
Standards such as S are provided, and it is required that the total thickness is 800 μm or less, which is extremely thin. Therefore, the battery built in this is also required to be molded as thin as possible.

Further, the IC card is required to be structurally excellent in flexibility so that it can withstand a certain amount of stress in its application. Therefore, the built-in battery also needs to have flexibility.

As a power source built in the IC card, a flat plate type battery in which a negative electrode, a separator, a positive electrode and an electrolyte substance are sandwiched between a pair of plate-shaped battery exterior materials is used.

In this flat plate type battery, a metal plate such as stainless steel is considered as a battery exterior material, but when it is used for an IC card, it is required to have flexibility as described above. For this reason, it has been attempted to use a multilayer film reinforced by coating a highly flexible polymer film such as polyolefin on both surfaces of a metal plate having an extremely thin thickness as a battery exterior material.

The use of this exterior material gives flexibility to the battery and at the same time allows the battery to be sealed by heat fusion, which simplifies the manufacturing process and is extremely advantageous in productivity. Become. Further, particularly in a battery system using lithium metal or the like as an electrode, which does not like contact with moisture, it is possible to improve the weather resistance by selecting a polymer film having high moisture resistance (Applications of
Electroactive polymers, Ed
s. by B. Scrosati, Chapman a
nd Hall, 1993). As such a multilayer film, a laminate of an aluminum plate and a polyamide film or a polyethylene film is commercially available as a general-purpose product.

[0008]

By the way, when the above-mentioned multilayer film is used as a battery exterior material, the current from the electrode cannot be taken out as it is because it is covered with a polymer film as an insulating material. . That is, it is necessary to provide an external terminal that is electrically connected to the electrode by using some kind of lead means.

Regarding the method of taking out such an external terminal, as shown in FIG. 6, lead wires 63A and 63C are attached to the negative electrode 61 and the positive electrode 62, respectively.
A method has been proposed in which 63C is taken out as an external terminal by crossing the heat-sealed portions of the battery exterior materials 64A and 64C.

However, when the lead wire is taken out in this way, the adhesive strength between the battery exterior materials is weakened at the part where the lead wire is taken out. Therefore, when external stress is applied to the battery, there is a problem that the sealing property of the battery is impaired from this portion.

Therefore, the present invention has been proposed in view of such a conventional situation, and provides a battery which is excellent in flexibility and moisture resistance, and is highly sealed even when external stress is applied. The purpose is to provide.

[0012]

In order to achieve the above-mentioned object, the battery of the present invention comprises an electrode in a battery exterior material composed of a multilayer film in which a fusible resin layer is coated on both surfaces of a conductive plate. And an electrolyte substance are housed, the inside and outside of the battery case is connected to a conductive plate by heat-sealing a lead member, and further, an electrode is connected to the inside lead member. There is.

[0013]

Embodiments of the present invention will be described with reference to the drawings.

A specific form of the battery of the present invention is shown in FIG.

In this battery, an electrode structure composed of a negative electrode 1, an electrolyte substance 2, a separator 3, an electrolyte substance 4 and a positive electrode 5 is laminated in this order, and a pair of plate-shaped battery exterior materials 7A, 7 are provided.
It is sandwiched by C and the outer edge portions of the battery exterior materials 7A and 7C are heat-sealed.

The pair of battery case materials 7A and 7C are provided on both sides of conductive plate bodies (conductive plates) 8A and 8C having a very small thickness of a micron unit, and a heat-fusible resin 9
It has a multi-layer film structure coated with A and 9C,
The outer edges are heat-sealed to each other to seal the battery.

Then, the pair of battery exterior materials 7A, 7C.
The inner and outer sides of the lead portion 10A, 10C,
The conductive plates 8A, 8 are formed by heat-sealing 11A, 11C.
The lead portions 10A and 10C which are connected to C and are heat-sealed to the inside of the battery exterior materials 7A and 7C are in contact with the negative electrode 1 or the positive electrode 5.

Therefore, in this battery, the negative electrode 1, the inner lead portion 10A on the negative electrode side, the conductive plate 8A, and the outer lead portion 11A are electrically connected, and the positive electrode 5, the inner lead portion 10C on the positive electrode side, and the conductive plate. 8C and the outer lead portion 11C are conducted. That is, the outer lead portion 11A on the negative electrode side and the outer lead portion 11C on the positive electrode side respectively function as an external terminal of the negative electrode and an external terminal of the positive electrode, and an electric current is taken in and out from this terminal.

Thus, the inner lead portions 10A and 10C are
And outer lead parts 11A and 11C are battery exterior materials 7A and 7C.
In the battery in which the external terminal is formed by heat fusion to
Compared with a battery in which the lead portion is taken out across the heat-sealed portion of the battery outer packaging material, the bonding state between the battery outer packaging materials becomes more uniform. Therefore, even when external stress is applied to the battery, peeling does not occur at the heat-sealed portion of the battery exterior material,
A high degree of battery tightness is maintained. Therefore, operational stability is obtained, long-term storage is possible, and reliability can be secured.

Assembly of such a battery is shown in FIG.
The steps shown in (a), (b) and FIGS. 3 (a) to 3 (c) are performed.

First, as shown in FIGS. 2A and 2B,
Inner lead portions 10A, 10C on the battery exterior materials 7A, 7C
The outer lead portions 11A and 11C are heat-sealed by a heater while applying an appropriate pressure. By this heat fusion, the inner lead portions 10A, 10C and the outer lead portions 11A, 11C are fixed in contact with the conductive plates 8A, 8C, so that the inner lead portions 10A, 10C and the outer lead portions 11
A and 11C are electrically connected through the conductive plates 8A and 8C.

Here, the inner lead portions 10A, 10
The fusion bonding positions of C and the outer lead portions 11A and 11C do not necessarily have to be the same, and the inner lead portions 10A and 10C
May be fused to a position where it comes into contact with the negative electrode or the positive electrode, and the outer lead portions 11A and 11C may be fused to appropriate positions according to the application.

Then, in this way, the lead portions 10A, 10
As shown in FIG. 3 (a), the negative electrode 1, the separator 3, and the positive electrode 5 are sandwiched between a pair of battery exterior materials in which C, 11A, and 11C are heat-sealed, and as shown in FIG. 3 (b). Then, the electrolyte substance 4 is added and these battery members are superposed. In this state, as shown in FIG. 3 (c), heat sealing is performed while applying an appropriate pressure to the outer edge portions of the battery exterior materials 7A and 7C, and the battery is assembled.

The following materials are used as the material of each constituent element of such a battery.

First, the battery exterior materials 7A, 7C are constructed by coating the heat-fusible resins 9A, 9C on both surfaces of the conductive plates 8A, 8C, but the conductive plates 8A, 8C are light in weight. In addition, a flexible metal is used, and for example, aluminum foil is advantageous in terms of cost. Further, as the heat-fusible resins 9A and 9C, those which can impart strength to a conductive plate having an extremely thin thickness and which can heat-bond the lead portion by a usual heat-bonding method are selected. . Examples of such a resin include, among known heat-bonding resins, polyolefin resins such as polyethylene and polypropylene, polyamide resins such as nylon, vinyl acetate resins, acrylic resins and epoxy resins. Etc. are preferred. Among the listed resins, polyethylene resin and polypropylene resin have low gas permeability and excellent chemical resistance, and are suitable as battery exterior materials. On the other hand, nylon resin is particularly excellent in terms of mechanical strength.

The lead portions 10A, 10C, 11A and 11C which are heat-sealed to the battery case materials 7A and 7C are not particularly limited in material and shape as long as they have conductivity. In consideration of the specific resistance, a metal foil such as copper, aluminum, nickel, iron, and stainless is preferable, and its shape is preferably mesh because it is easily adhered by the fusible resin.

As the negative electrode 1, the positive electrode 5, the separator 3 and the electrolyte substance 4, any of those used in conventionally known battery systems can be adopted. In particular, when the present invention is applied to a lithium battery system using lithium metal as the negative electrode active material, moisture resistance can be imparted to the battery by selection of the heat-fusible resin used for the battery exterior material, and therefore it is also effective in improving weather resistance. There is.

However, as the electrolyte substance 4, it is desirable to use a solid or gel electrolyte because it is easy to handle during battery assembly and there is no risk of liquid leakage. For example, in a lithium battery, a gel electrolyte obtained by adding polyacrylonitrile as a gelling agent to the composition of a non-aqueous electrolyte can be used.

If the electrode active material has low conductivity, the electrode may be provided with a current collector. In this case, the current collector is arranged on the side of the exterior material, and the current collector is in contact with the inner lead. A metal mesh is suitable for this collector.

[0030]

EXAMPLES Examples of the present invention will be described based on experimental results.

Example 1 First, a battery exterior material was produced as follows.

On both sides of an aluminum foil having a thickness of 40 μm,
A three-layer film having a total thickness of 100 μm was prepared by heat-sealing a polyethylene film having a thickness of 30 μm.
It was cut into a size of × 4 cm ² .

Then, the inner lead portion and the outer lead portion were heat-bonded to each other on the both surfaces of the battery exterior material thus produced by aligning the locations and applying pressure by the heat pulse method. The inner lead portion and the outer lead portion are made of stainless steel mesh (SUS304) having a size of 0.5 × 0.5 cm ² and a thickness of 30 μm. ^Two sides are provided at a position 1 cm away from the center of the battery exterior material in the one side direction. Heat fusion was performed so as to be parallel to. During this heat fusion, the state of conduction between the inner lead portion and the outer lead portion was examined with a tester, and if the conduction was insufficient, the heat fusion operation was repeated.

Next, a positive electrode was prepared as follows.

90 parts by weight of powdered manganese dioxide, 3 parts by weight of powdered polyvinylidene fluoride and 7 parts by weight of powdered graphite were dispersed in dimethylformamide (DMF) as a solvent to prepare a positive electrode mixture slurry. Next, this positive electrode mixture slurry was applied to an aluminum mesh serving as a current collector and dried under reduced pressure at a temperature of 100 ° C. for 24 hours. Subsequently, the positive electrode material mixture layer formed on the current collector was roll-pressed at an appropriate pressure to be compressed to a thickness of 130 μm and cut into a size of 2 × 2 cm ² to produce a positive electrode. Then, the current collector side of this positive electrode was spot-welded to the inner lead portion of the battery exterior material.

Next, a negative electrode was prepared by cutting Li metal into a size of 2 × 2 cm ² and compressing it to 130 μm. Then, this negative electrode was pressure-bonded to the inner lead portion of the battery outer casing different from the one to which the positive electrode was welded.

On the other hand, as the electrolyte substance, polyacrylonitrile (PAN), ethylene carbonate (EC),
A gel electrolyte composed of propylene carbonate (PC) and lithium perchlorate (PAN: EC: PC: lithium perchlorate (molar ratio) = 13: 55: 27: 5) was used. The gel electrolyte was formed as follows.

After adding a predetermined amount of lithium perchlorate into a beaker in which a predetermined amount of EC and PC were mixed and stirred,
It was heated to 100 ° C. Then, when sufficiently heated, a predetermined amount of PAN is added little by little, and after the addition is completed,
Heated and stirred for 10 minutes. As a result, PAN is completely dissolved and a viscous solution is obtained. At this point, heating was terminated, and the obtained solution was immediately cast on the positive electrode in an appropriate amount to form a gel electrolyte. Further, a gel electrolyte was similarly formed on the negative electrode.

The positive electrode and the negative electrode on which the gel electrolyte was formed as described above were stacked with a polypropylene non-woven fabric having a thickness of 50 μm serving as a separator interposed therebetween, and the outer edge portion of the battery exterior material was heat-fused to form a battery. Was sealed to produce a thin battery.

Comparative Example 1 The inner lead portion and the outer lead portion were not heat-sealed to the battery outer packaging material, but the lead portions were taken out to the outside as shown in FIG. 6 across the heat-sealed portion of the battery outer packaging material. A thin battery was produced in the same manner as in Example 1 except for the above.

For the battery manufactured as described above, a bending test was conducted in order to verify the airtightness, and then a discharge test was conducted.

In the bending test, as shown in FIG. 4, the central portion of the battery 12 was fixed by sandwiching it by a pair of square members 13 having a width of 0.5 cm and a crossover of 8 cm, and both ends of the battery were kept at room temperature and normal humidity. The operation of moving up and down 1.0 cm in the direction perpendicular to the plane was repeated 300 times.

The discharge test was carried out by leaving the battery subjected to the bending test under normal temperature and normal humidity for 24 hours and then discharging it with a constant current of 500 μA until the closed circuit voltage reached 1.8 V. . The discharge capacity was estimated from the voltage change during this discharge process. The relationship between discharge time and battery voltage is shown in FIG.

As is apparent from FIG. 5, in comparison with the battery of Example 1 in which the lead portions were heat-sealed to the battery outer casing material, the lead wires of Comparative Example 1 were taken out from the heat-sealed portion of the battery outer casing material. The voltage of the battery begins to drop early and a sufficient discharge capacity cannot be obtained. This is because the battery of Comparative Example 1 had a low sealing property due to the bending test, which caused performance deterioration.

Further, both batteries were disassembled after the test,
When the inside was observed, a large amount of white powder attributed to lithium hydroxide was observed inside the battery of Comparative Example 1. On the other hand, in the battery of Example 1, the lithium metal was maintained in a glossy state.

From the above results, it is found that the external terminals of the battery are formed by heat-sealing the lead portions to the battery exterior material.
It has been found that it is effective in obtaining a battery with high sealing performance that can withstand external stress.

[0047]

As is apparent from the above description, in the battery of the present invention, the electrode and the electrolyte substance are housed in the battery exterior material in which both surfaces of the conductive plate are covered with the fusible resin layer. On the inside and outside of the battery exterior material,
Since the lead terminals are heat-sealed to form the external terminals, flexibility and moisture resistance are obtained, and high sealing performance is maintained even when external stress is applied to the battery. Therefore, it is very suitable as a power source for an IC card to which external stress may be applied.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing one structural example of a battery to which the present invention is applied.

FIG. 2 shows a heat-sealing process of the lead portion,
(A) is a schematic diagram showing a lead part alignment step,
(B) is a schematic diagram which shows the heat-sealing process of a lead part.

3A and 3B are diagrams showing a process of assembling a battery, wherein FIG. 3A is a schematic diagram showing a positional relationship between a battery exterior material, a negative electrode, a separator, and a positive electrode, and FIG. 3B is a schematic diagram showing a stacking process of these members; (C) is a schematic diagram which shows the sealing process of a battery.

FIG. 4 illustrates a bending test of a battery,
(B) is a cross-sectional view of a battery sandwiched between square pieces, and (c) is a perspective view thereof.

FIG. 5 is a characteristic diagram showing a relationship between a battery discharge time and a battery voltage after a bending test.

FIG. 6 is a cross-sectional view showing a terminal structure in a conventional battery.

[Explanation of symbols]

 1 Negative Electrode 2,4 Electrolyte 3 Separator 5 Positive Electrode 7A, 7C Battery Exterior Material 8A, 8C Conductive Plate 9A, 9C Thermofusible Resin Layer 10A, 10C Inner Lead Part 11A, 11C Outer Lead Part

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] December 28, 1995

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Fig. 4

[Correction method] Change

[Correction contents]

FIG. 4 illustrates a bending test of a battery,
(A) is a cross-sectional view of a battery sandwiched between square pieces, and (b) is a perspective view thereof.

Claims (4)

[Claims] 1. A battery in which an electrode and an electrolyte substance are housed in a battery exterior material made of a multi-layer film in which a fusible resin layer is coated on both surfaces of a conductive plate, wherein the inside and the outside of the battery exterior material. The battery is characterized in that the lead portion is connected to the conductive plate by heat-sealing each of them, and the electrode is connected to the inner lead portion. 2. The battery according to claim 1, wherein the lead portion is a metal net. 3. The battery according to claim 1, wherein the electrode is provided with a current collector, and the lead portion inside the battery casing is connected to the current collector. 4. The battery according to claim 3, wherein the current collector of the electrode is a metal net.