JP2012015004A - Thin profile battery and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin profile battery which is encapsulated with two exterior members oppositely provided and also serving as external terminals by bonding their peripheral edges together with resin and which excels in both adhesive strength and moisture penetration restraining ability, making it durable for a long period of use.SOLUTION: A thin profile battery has a power generation element contained between a first exterior member which doubles as an external terminal for one electrode of oppositely provided electrodes and a second exterior member which doubles as an external terminal for the other electrode, the first exterior member and the second exterior member being insulated by the resin provided between the peripheral edges of the first exterior member and the second exterior member. In the thin profile battery, more specifically, the first exterior member and the second exterior member are insulated by a first resin which bonds the peripheral edges of the first exterior member and the second exterior member together and by a second resin which restrains moisture content from penetrating from the peripheral edges of the first exterior member and the second exterior member.

Description

The present invention relates to a thin battery using, for example, a lithium ion (Li ⁺ ) conductive solid electrolyte or a non-aqueous electrolyte and a method for manufacturing the same.

As electronic devices become smaller and thinner, batteries are required to be thinner. For example, in a lithium battery using a Li ⁺ conductive solid electrolyte or a non-aqueous electrolyte, the conventional sealing method by caulking a gasket can only be reduced to about 1.4 mm. Therefore, it is difficult to achieve a sufficient thinning required today.

  For this reason, for example, a battery (electrochemical element) in which a first external terminal that also serves as a constituent member of an exterior body is opposed to a second external terminal, and an insulating sealing member made of polyphenylene sulfide is thermally welded to the peripheral end face thereof. Has been developed (for example, Patent Document 1). FIG. 3 is a cross-sectional view schematically showing an example of the structure of the thin battery 31 thus sealed by adhesion. The peripheral portions of the first exterior member 32 and the second exterior member 33 that also serve as external terminals are sealed by being bonded via a resin 36. Reference numeral 34 denotes a power generation element, and 35 denotes a conductive spring.

  Further, as a sealing resin, a thin battery using a three-layer structure resin (sealing material) in which a metal adhesive resin layer is provided on both sides and the inside is a gas barrier resin layer has been developed (for example, Patent Document 2). ). FIG. 4 is a cross-sectional view schematically showing the structure of such a thin battery 41. In FIG. 4, the peripheral portions of the first exterior member 42 and the second exterior member 43 are bonded together via a resin (seal material) 47 having a three-layer structure of a metal adhesive resin layer 45 and a gas barrier resin layer 46. It is sealed by. Reference numeral 44 denotes a power generation element.

Japanese Patent No. 4,390,426 JP 2009-206102 A

  However, in the method of sealing using the single sealing resin shown in FIG. 3, it is difficult to obtain a sufficient adhesion function and a moisture sealing function (permeation suppression function) at the same time. That is, a resin having an excellent adhesion function is generally a hydrogen-bonding resin, so that moisture easily passes therethrough. On the other hand, a resin having an excellent sealing function does not have a sufficient adhesion function. Therefore, there is a problem that it is difficult to produce a thin battery that can withstand long-term use. Further, in the method of sealing using the sealing resin having a three-layer structure shown in FIG. 4, the balance between the adhesion function and the sealing function is improved, but the sealing function is not always satisfactory.

  Therefore, the present invention is a thin battery in which the peripheral portions of two exterior members also serving as external terminals provided opposite to each other are bonded together with a resin and sealed. It is an object of the present invention to provide a thin battery that has excellent suppression function and can withstand long-term use.

  As a result of intensive studies on the sealing structure of a thin battery, the present inventor has found a means that can solve the above problems and has completed the present invention. Hereinafter, means for solving the problems will be sequentially described.

(1) The thin battery of the present invention is
A power generation element is housed between a first exterior member that also serves as an external terminal of one of the electrodes and a second exterior member that also serves as an external terminal of the other electrode, the first exterior member and the second exterior member. A thin battery in which the first exterior member and the second exterior member are insulated by a resin provided between the peripheral portions of the members,
A first resin for adhering peripheral edges of the first exterior member and the second exterior member;
A thin battery characterized in that the first exterior member and the second exterior member are insulated by the first resin and the second resin that suppresses moisture permeation from the periphery of the second exterior member. is there.

  In the present invention, as the resin for insulation, since the role is divided using the adhesive resin and the sealing (moisture permeation suppression) resin according to each role, each characteristic is fully exhibited. Thus, it is possible to provide a thin battery that is sufficiently excellent in both an adhesion function and a sealing function and can withstand long-term use.

  In addition, resin excellent in adhesiveness with metals, such as an epoxy resin and an acrylic resin, is preferably used for 1st resin. For the second resin, a resin having an excellent water permeation suppressing function such as polyaramid, polyethylene naphthalate, tetrafluoroethylene perfluoroalkyl vinyl ether copolymer (PFA), and fluorinated ethylene propylene (FEP) is preferably used.

(2) The thin battery of the present invention is
Said thin battery,
The second resin is any one of polyaramid, polyethylene naphthalate, tetrafluoroethylene perfluoroalkyl vinyl ether copolymer, and fluorinated ethylene propylene.

  Since these resins have a particularly excellent water permeation suppressing function, a thin battery having an extremely excellent water permeation suppressing function can be provided.

(3) The thin battery of the present invention is
Said thin battery,
The resin has a thickness of 5 to 100 μm.

  The optimum thickness of the resin in consideration of the amount of resin required for adhesion and sealing and the thinning of the battery is 5 to 100 μm.

(4) The thin battery of the present invention is
Said thin battery,
The first resin is provided on an outer peripheral portion of the second resin.

  By providing the adhesive resin on the outer periphery of the sealing resin, a thin battery having an excellent sealing function can be provided.

(5) The method for producing a thin battery of the present invention comprises:
A method of manufacturing the thin battery,
The second resin is provided by sticking a moisture permeation suppression type resin sheet to the peripheral portions of the first exterior member and the second exterior member.

  By sticking a moisture permeation suppression type resin sheet to the peripheral portions of the first exterior member and the second exterior member, the second resin can be reliably provided by a simple operation without requiring an expensive device. it can.

(6) Moreover, the manufacturing method of the thin battery of this invention is as follows.
A method of manufacturing the thin battery,
The first resin is provided by sticking or molding an adhesive resin as a sheet on a peripheral portion of the first exterior member and the second exterior member.

  In order to sufficiently secure the bonding function, it is preferable to provide the first resin by adhering an adhesive resin as a sheet to the peripheral portions of the first exterior member and the second exterior member, or by molding. In particular, since the first resin is provided by molding (insert molding) the adhesive resin on the peripheral portions of the first exterior member and the second exterior member, the opposing surfaces of the first exterior member and the second exterior member are provided. In addition, the adhesive resin can be disposed on the side surfaces of the first exterior member and the second exterior member. For this reason, it is possible to suppress the uneven application of the adhesive resin between the opposing surfaces of the first exterior member and the second exterior member (elimination of unapplied portions) and to have a stable adhesive strength. Moreover, the short circuit by the contact between positive and negative can be suppressed by arrange | positioning resin to the side surface of a 1st exterior member and a 2nd exterior member.

  According to the present invention, it is possible to provide a thin battery that is sufficiently excellent in both an adhesion function and a sealing function and can withstand long-term use.

It is sectional drawing which shows typically the structure of the thin battery of one embodiment of this invention. It is sectional drawing which shows typically the structure of the thin battery of one Example of this invention. It is sectional drawing which shows typically an example of the structure of the conventional thin battery. It is sectional drawing which shows typically the other example of the structure of the conventional thin battery.

  Hereinafter, the present invention will be described based on embodiments with reference to the drawings.

1. Structure (1) Outline of Thin Battery First, the structure of the thin battery of the present invention will be described. FIG. 1 is a cross-sectional view schematically showing the structure of a thin battery 1 according to an embodiment of the present invention. In FIG. 1, 2 is a first exterior member also serving as an external terminal of one electrode, 3 is a second exterior member also serving as an external terminal of the other electrode, 4 is a power generation element, and 5 is a spring having conductivity. Reference numeral 8 denotes a resin, which includes a first resin 6 for adhesion and a second resin 7 for sealing. For convenience of understanding the drawings, the scale between the constituent members is appropriately modified.

The first exterior member 2 and the second exterior member 3 are made of, for example, a SUS plate and are provided to face each other. Between the first exterior member 2 and the second exterior member 3, for example, a power generation element in which a positive electrode made of a composite oxide of Li and a transition metal, a negative electrode made of a lithium ion (Li ⁺ ) conductive solid electrolyte, and a metal Li are stacked. 4 and a conductive spring 5 are provided, and the positive electrode and the negative electrode are connected to one of the first exterior member 2 and the second exterior member 3, respectively.

  Resin 8 is provided at the peripheral portions of the first exterior member 2 and the second exterior member 3, and the first exterior member 2 and the second exterior member 3 are insulated and sealed between the peripheral portions. ing.

(2) Resin The resin 8 is composed of a first resin 6 such as an epoxy resin having an excellent adhesion function with respect to the first exterior member 2 and the second exterior member 3, and a first resin 6 such as polyaramid having a small moisture permeation amount and an excellent sealing function. The first resin 6 adheres the peripheral portions of the first exterior member 2 and the second exterior member 3, and the adjacent second resin is formed between the first exterior member 2 and the second exterior member 3. Close contact between the peripheral portions and seal between the peripheral portions.

  As described above, the resin 8 is composed of the first resin 6 having an excellent adhesion function and the second resin 7 having an excellent sealing function, whereby the first exterior member 2 and the second exterior member 3 can be bonded and sealed. Both can provide an excellent thin battery. The width of the first resin 6 is appropriately set so that sufficient adhesive strength can be obtained, and the width of the second resin 7 is appropriately set so that the moisture permeation amount is sufficiently small.

2. Thin battery manufacturing method (1) Production of power generation element For production of a power generation element, for example, a vapor phase growth method suitable for forming a thin film such as a sputtering method or a vacuum evaporation method or a method using a powder metallurgy method using powder as a raw material is used. Preferably used. For example, using the second exterior member as a substrate, a positive electrode having a predetermined thickness, a solid electrolyte, and a negative electrode are sequentially laminated on the surface using a vapor phase growth method to produce a power generation element.

(2) Attaching the second resin For example, in a state where the second resin 7 is adhered to the first exterior member 2 by bonding a sheet of polyaramid or polyethylene naphthalate as the second resin to the peripheral portion of the first exterior member 2. Deploy. By laminating in this way, the second resin 7 can be disposed without gaps between the first exterior member and the second exterior member facing each other, and thus the amount of moisture permeation can be further suppressed. .

(3) Adhesion with the first resin After the second resin 7 is provided on the first exterior member 2, the outer peripheral portion of the second resin is filled with, for example, an epoxy resin as the first resin, 2 Overlaying the exterior member, the peripheral portions of the superimposed first exterior member and the second exterior member are heated to 150 ° C. or higher under a pressure of 0.1 to 3 MPa to cure the epoxy resin, The second exterior member is bonded, or the first resin is insert-molded and cured by the temperature inside the mold. In this way, a thin battery excellent in adhesion function and sealing function having a thickness of about 0.4 to 0.7 mm can be produced.

1. Production of thin battery (1) Structure and size of thin battery (Examples 1 to 4)
FIG. 2 is a cross-sectional view schematically showing the structure of the thin battery 21 of this example. Reference numerals 22 and 23 respectively denote a first exterior member and a second exterior member made of a SUS plate, 24 is a power generation element, and 27 is an entire resin portion made up of a first resin 25 and a second resin 26.

The thin battery 21 is a circle having a thickness of 0.33 mm and a diameter of 10 mmφ, and the configuration and dimensions of the constituent members are as follows. In addition, the resin shown in Examples 1-4 of Table 1 and Table 2 was used for 1st resin and 2nd resin.
First and second exterior members: made of SUS board
Thickness 0.15mm, diameter 16mmφ
Power generation element: positive electrode LiCoO ₂ , solid electrolyte Li ₂ S—P ₂ S ₅ composite,
Negative electrode Li alloy
Thickness 0.03mm, diameter 10mmφ
First resin: heat 0.03mm, width 0.25mm
Second resin: thickness 0.03 mm, width 0.25 mm

  A thin battery was manufactured by the method described in the above embodiment using the above-described constituent members. In addition, adhesion | attachment of resin was performed under the pressurization of 180 degreeC and 1 Mpa.

(Comparative Example 1)
A thin battery was produced in the same manner as in Example except that the first resin shown in Comparative Example 1 of Table 1 was used alone as the resin 27.
(Comparative Examples 2 and 3)
A thin battery was produced in the same manner as in Example except that the second resin shown in Comparative Examples 2 and 3 in Table 2 was used alone as the resin 27.

(2) Resin a. Table 1 shows the material of the first resin and the adhesive strength to the exterior member.

  As shown in Table 1, the first resin used in Examples 1 to 4 has higher adhesive strength than the first resin used in Comparative Example 1.

B. Second Resin Table 2 shows the material and moisture permeation amount of the second resin.

  As shown in Table 2, the second resin used in Examples 1 to 4 has a smaller water permeation amount than the second resin used in Comparative Examples 2 and 3.

2. Performance Evaluation of Thin Battery (1) Test Method Each of the batteries of Examples 1 to 4 and Comparative Examples 1 to 3 was cut off in an air atmosphere and at room temperature, with a cutoff voltage of 3.0 V to 4.2 V, a current density of 0. A charge / discharge cycle test was performed under the condition of 05 mA / cm ² , and a capacity retention rate (%) was obtained by expressing the discharge capacity after 100 cycles with respect to the initial discharge capacity as a relative value.

(2) Test results Table 3 shows the test results of Examples and Comparative Examples.

  From Table 3, it can be seen that the capacity retention rates of Examples 1 to 4 are high. The reason why the capacity retention rate of the example is high in this way is that the bonding function and the sealing function are both excellent by sharing each role between the first resin and the second resin.

  As described above, according to the present invention, a thin battery that can withstand long-term use can be produced.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to said embodiment. Various modifications can be made to the above-described embodiment within the same and equivalent scope as the present invention.

1, 21, 31, 41 Thin battery
2, 22, 32, 42 First exterior member
3, 23, 33, 43 Second exterior member 4, 24, 34.44 Power generation element 5, 35 Spring 6, 25, First resin 7, 26 Second resin 8, 27, 36 Resin 45 Metal adhesive resin layer 46 Gas barrier resin layer 47 Sealing material

Claims (6)

A power generation element is housed between a first exterior member that also serves as an external terminal of one of the electrodes and a second exterior member that also serves as an external terminal of the other electrode, the first exterior member and the second exterior member. A thin battery in which the first exterior member and the second exterior member are insulated by a resin provided between the peripheral portions of the members,
A first resin for adhering peripheral edges of the first exterior member and the second exterior member;
A thin battery, wherein the first exterior member and the second exterior member are insulated by the first resin and the second resin that suppresses moisture permeation from the peripheral portion of the second exterior member.   2. The thin battery according to claim 1, wherein the second resin is any one of polyaramid, polyethylene naphthalate, tetrafluoroethylene perfluoroalkyl vinyl ether copolymer, and fluorinated ethylene propylene.   The thin battery according to claim 1, wherein the resin has a thickness of 5 to 100 μm.   The thin battery according to any one of claims 1 to 3, wherein the first resin is provided on an outer peripheral portion of the second resin. A method of manufacturing a thin battery according to any one of claims 1 to 4,
A method for producing a thin battery, characterized in that the second resin is provided by bonding a moisture permeation suppression type resin sheet to the peripheral portions of the first exterior member and the second exterior member. A method of manufacturing a thin battery according to any one of claims 1 to 4,
A method for producing a thin battery, characterized in that the first resin is provided by adhering an adhesive resin as a sheet to the peripheral portions of the first exterior member and the second exterior member, or by molding.

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