JPH10125330A - Thin type battery using polymeric solid electrolyte - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase adhesive strength and prevent the occurrence of a short circuit across positive electrode and negative electrode components by laying a positive electrode active material, so as to occupy an area smaller than the arrangement area of a conductive assistant, and keeping the thickness of the conductive assisting agent at a value smaller than the thickness of the positive electrode material. SOLUTION: A prerequisite is established, so that a distance between the outside dimensions of a conductive assistant and a positive electrode active material is equal to or larger than 0.1mm, the conductive assisting agent has thickness equal to or less than 1/13 of the thickness of the positive electrode active material, and the conductive assisting agent has a liquid absorbing function. A conductive assisting agent 10 is screen printed on a positive electrode current collector 9 (e.g. stainless steel foil), so as to keep a peripheral part in a corrugated state and dried, thereby forming a porous layer of approximately 0.01mm thickness. The extent of the corrugation can be controlled by keeping a large screen plate mesh and increasing a wire diameter. In this case, the length of each corrugation is preferably equal to or less than approximately 1mm, from a viewpoint of a liquid collection function. Also, a positive electrode active material 11 is printed on the conductive assistant 10 over a small area at a position approximately 0.5mm away from respective ends and exposed to electron beams, thereby preparing a positive electrode. On the other hand, a polymeric solid electrolyte 13 is printed on the metallic lithium 12 of the negative electrode active material at the center of a negative electrode current collector 16. A negative electrode is thereby prepared.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin battery used as a power source for ID / IC cards, distribution tags, high-tech electronic equipment, portable equipment, toys, stationery, accessories and the like.

[0002]

2. Description of the Related Art A case in which metallic lithium is used as a conventional thin battery will be described. FIG. 3 is a perspective view of a characteristic positive electrode current collector, and FIG. 4 is a cross-sectional view thereof. A frame-shaped adhesive 2 is thermally bonded to a peripheral region of a positive electrode current collector 1 made of stainless steel foil, and a conductive auxiliary agent 3 is printed on a central region of the positive electrode current collector 1. The positive electrode active material 4 was disposed over an area larger than the area and over the entire area inside the adhesive 2. On the other hand, an adhesive 6 larger in both outer dimension and inner dimension than the adhesive 2 is thermally bonded to the peripheral region of the negative electrode current collector 5 made of stainless steel foil, and then the negative electrode active material 7 Metallic lithium was pressed, and a solid polymer electrolyte 8 was arranged by screen printing over an area larger than the negative electrode active material 7. After the positive electrode and the negative electrode were cured with an electron beam, the adhesive around the battery was pressurized in a heated state, whereby the adhesives 2 and 6 of the respective current collectors were adhered to each other to seal the inside of the battery. FIG. 5 shows a cross-sectional view thereof.

[0003] As a result of a storage test of such a conventional thin battery, the self-discharge rate was about 25% after 100 days at 60 ° C and 95% humidity. Some of the batteries after the test had an adhesive seal opening, and there was a problem with the adhesive. Further, bonding the adhesive to each current collector in advance increases the number of processing steps. In addition, each current collector is deformed due to the heat shrinkage of the adhesives 2 and 6, which makes it difficult to arrange the active material in the next step, resulting in poor positional accuracy, and the solid polymer electrolyte 8 adheres to the adhesive 6. In addition to lowering the airtightness of the above-mentioned bonded portion, the end of the positive electrode active material 4 may penetrate the polymer solid electrolyte 8 and contact with the negative electrode active material 7 to cause a short circuit.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to spread a solution component in a positive electrode active material, such as an electrolyte, to a region to be bonded. The positive electrode current collector and the negative electrode when the inside of the battery is depressurized and sealed are sealed. An object of the present invention is to provide a current collector or a thin battery that prevents a short circuit between a positive battery component and a negative battery component.

[0005]

SUMMARY OF THE INVENTION The present invention achieves the above object and provides a thin film using a solid polymer electrolyte in which a conductive auxiliary is disposed on a positive electrode current collector surface and a positive electrode active material is disposed thereon. In the shape battery, the positive electrode active material is arranged in an area smaller than the arrangement area of the conductive auxiliary, the outer dimension distance between the conductive auxiliary and the positive electrode active material is 0.1 mm or more, and the thickness of the conductive auxiliary is Being not more than 1/13 of the thickness of the active material, that the conductive auxiliary agent is liquid-absorbing, that at least the outer peripheral portion of the conductive auxiliary agent is spotted or wavy,
The distance between the conductive auxiliary agent and the adhesive sealing material for sealing the peripheral area of the current collector is 0.1 mm to 1.5 mm, and the thickness of the thin battery is 0.2 mm to 0.6 mm. The present invention is characterized in that the above-mentioned problems are solved.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first and second aspects of the present invention, when a positive electrode active material is printed by a metal mask method, a defective portion that cannot be printed due to slip on the positive electrode current collector surface does not occur. According to the third aspect of the present invention, the electrolyte component that has permeated out of the positive electrode active material is absorbed by the conductive auxiliary and does not permeate out of the conductive auxiliary, so that the adhesive portion is not contaminated and the sealing property is improved. The life is improved. If the outer dimension distance between the positive electrode active material and the conductive auxiliary agent is smaller than 0.1 mm, the electrolyte component cannot be absorbed and the electrolyte component adheres to the intended area of the adhesive seal, lowering the adhesive strength and shortening the service life. Make you worse. Also,
If the battery capacity is too large when the battery capacity is constant, the thickness of the positive electrode active material becomes large, the polymer monomer in the positive electrode active material cannot be cured by the electron beam, and the retention of the electrolyte component deteriorates. In this case, the amount of bleeding is increased, and the adhesiveness is deteriorated. Preferred outer dimension distance is 0.1 mm or more
1.5 mm. However, since the maximum external distance is related to the size and capacity of the battery, it is not limited in the present invention, but by setting the thickness of the conductive auxiliary agent to be not more than 1/13 of the thickness of the positive electrode active material, Component Retention and Polymer Monomer
The adhesive strength is increased by increasing the curability of the resin, and the adhesive strength is about 35 to 50 g / mm width outside the range, whereas it is about 55 to 115 g / mm width within the range.

According to the fourth aspect, the outer peripheral length of the conductive auxiliary agent is long, and the surface tension acts on the recessed portion, so that the electrolyte component or the like having a liquid absorption amount or more can be attracted, and seepage into the bonding expected area. Can be prevented.

According to a fifth aspect of the present invention, the distance between the conductive auxiliary agent and the adhesive sealing material for sealing the peripheral area of the current collector is 0.1 m.
m to 1.5 mm, and the thickness of the thin battery is 0.2 mm to
By setting the thickness to 0.6 mm, it is possible to prevent the exudation of the electrolyte component in the positive electrode active material and to prevent the internal short circuit in the space between the adhesive and the battery element (active material, polymer solid electrolyte, etc.). . That is, when the inside of the battery is sealed under reduced pressure,
When the current collector is pressed at 1 atm and is deformed inward, it is possible to prevent the current collector surfaces from contacting each other or the active material.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a production processing diagram of a positive electrode current collector according to the present invention. On a positive electrode current collector 9 (stainless steel foil, nickel-plated stainless steel foil, aluminum foil, or the like), a conductive auxiliary agent 10 (for example, a conductive material such as carbon, an organic binder, or a solvent) so that the outer peripheral portion becomes wavy. About 0.01 mm after screen printing and drying.
To be porous. The outer dimensions at this time are 2
The size was 5.1 mm × 18.1 mm. The degree of the wavy shape can be controlled by enlarging the mesh of the screen plate and increasing the wire diameter. The wave-like wavelength is preferably about 1 mm or less from the viewpoint of liquid-trapping property. If it is 1 mm or more, the electrolyte solution component spread on the current collector surface in the portion corresponding to the valley of the wavy portion cannot be absorbed and diffuses.

Next, about 0.5 m is placed on the conductive auxiliary agent 10 surface.
m Smaller area away from each end (external dimensions are 24.
A positive electrode active material 11 (for example, a mixture of manganese dioxide as a main component, a conductive agent and a polymer solid electrolyte) having a size of about 1 mm × 17.1 mm and a thickness of about 0.210 mm is printed, and the positive electrode is irradiated with an electron beam. The active material 11 was cured to produce a positive electrode. In a separate step, a negative electrode active material is disposed in the center of the negative electrode current collector 16 with metallic lithium 12 (there are other lithium aluminum alloys, carbon, and the like), and a polymer solid electrolyte 13 is printed thereon to form a negative electrode. Produced. The peripheral area of such a positive electrode and a negative electrode is heated by a frame-shaped adhesive sealing material 14 (for example, modified polypropylene or the like, the inner size of which is 26.7 mm × 19.7 mm) in a hatched area shown as an area 15 to be bonded. It was crimped and sealed. FIG. 2 shows a cross-sectional view thereof.

A destruction test, a storage test, and a discharge test were performed on 50 cells shown in the sectional view of FIG. The T-shaped tensile strength of the bonded portion was about 75 to 110 g / mm width, and the average was about 90 g / mm width. Further, the inner size of the adhesive sealing material extends inward due to thermal deformation and is about 26.1 mm × 19.
It was 1 mm ± 0.15 mm. However, the electrolyte component and the like did not adhere to the extended portion. After 120 days at 60 ° C. and 95% humidity as a storage test, the battery was discharged at 20 ° C. and 0.3 mA until the final voltage reached 2.0 V as a discharge test. As a result, the battery capacity was about 33.7 mAh ± 0.
8 mAh, about 37.4 mA average battery capacity before storage
On average, the reduction was only about 10% with respect to h. There was no battery showing a voltage drop due to an internal short circuit.

[0012]

As described above, the present invention has the following effects. (1) The exudation and spread of the electrolyte component in the positive electrode active material could be suppressed. (2) Since the exuded electrolyte component is absorbed and trapped to prevent spreading to a region other than the predetermined region, the surface to be bonded is not contaminated, and the bonding strength is increased and stabilized, and the battery life is improved. (3) The self-discharge rate is less than half of the conventional one. (4) Internal short circuit was prevented. (5) Since the arrangement of the adhesive sealing material and the adhesive area are not contaminated, the reliability of the battery is improved.

It should be noted that the present invention is not limited to the above-described embodiment, and the porosity and composition are not limited. The conductive auxiliary agent may be conductive or non-conductive particularly at the peripheral portion, but non-conductive is preferable in that the risk of a short circuit inside the battery can be prevented. However, at least the surface in contact with the positive electrode active material needs to have electrical conductivity.
Further, the undercoat agent may be slightly separated from the outer dimension of the positive electrode active material to form a breakwater (for example, a shape like a double frame).

[Brief description of the drawings]

FIG. 1 is a plan view showing a state of manufacturing a positive electrode according to the present invention.

FIG. 2 is a cross-sectional view showing a thin battery according to the present invention.

FIG. 3 is a plan view showing a positive electrode current collector of a conventional thin battery.

FIG. 4 is a cross-sectional view showing a positive electrode current collector of a conventional thin battery.

FIG. 5 is a cross-sectional view of a conventional thin battery.

[Explanation of symbols]

 1, 9 Positive electrode current collector 2, 6 Adhesive material 14 Adhesive sealing material 3, 10 Conductive auxiliary agent 4, 11 Positive electrode active material 5, 16 Negative current collector 7, 12 Negative electrode active material 8, 13 Polymer solid electrolyte 15 Adhesion Planned area

Claims (5)

[Claims] Claims: 1. A conductive auxiliary is disposed on a positive electrode current collector surface,
In a thin battery using a solid polymer electrolyte in which a positive electrode active material is disposed thereon, the positive electrode active material is disposed in an area smaller than an area where the conductive auxiliary is disposed, and the thickness of the conductive auxiliary is reduced. A thin battery using a polymer solid electrolyte, characterized in that the thickness is smaller than the thickness of the battery. 2. A conductive auxiliary agent is disposed on the positive electrode current collector surface,
In a thin battery using a polymer solid electrolyte in which a positive electrode active material is disposed thereon, the positive electrode active material is disposed in an area smaller than the conductive auxiliary agent, and the external distance between the conductive auxiliary and the positive electrode active material is reduced. Is 0.1 mm or more, and the thickness of the conductive auxiliary agent is 1/13 or less of the thickness of the positive electrode active material. 3. The thin battery using the solid polymer electrolyte according to claim 1, wherein the conductive auxiliary has a liquid absorbing property. 4. The thin battery using the polymer solid electrolyte according to claim 1, wherein at least the outer peripheral portion of the conductive auxiliary agent is formed in a spot-like or wavy shape. 5. The distance between the conductive auxiliary agent and an adhesive sealing material for sealing the peripheral area of the current collector is 0.1 mm to 1.5 m.
m, and the thickness of the thin battery is 0.2 mm to 0.6 mm.
A thin battery using the solid polymer electrolyte according to claim 1.