JPH11120989A - Electrode structure of battery case - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the danger of short circuit by covering the terminal of an electrode with an insulating sheet having at least one cutout part every terminal of each pole in a part situated on the outside of a battery case. SOLUTION: An electrode terminal P consists of a flat terminal of metal foil or the like, and both sides of the electrode terminal P except a contact area or the connecting part to a target equipment is covered with an electrode protecting film F having insulating property. A cutout part 2 is provided in a prescribed position so that the cutout part 2 is conformed to the position to form the contact area with each terminal P of plus electrode and minus electrode when the film F is folded in two. The electrode terminal P is put between the two-folded film F, and adhered thereto by means of heat seal, and the inner surfaces of the film F are thermally fused together in the terminal peripheral part. Thus, the short-circuit between the metal foil of the layer product constituting a battery case and the electrode is prevented, and the electrode terminal P can be prevented from being bent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an electrode protruding out of a battery case.

[0002]

2. Description of the Related Art In a relatively flat battery such as a polymer battery, a battery case is formed of a flexible material having a laminated structure, and an electromotive portion of the battery is housed in the battery case. The electrode is designed to extend to the outside of the case and be connectable to a device to be used. In addition, it is required to make the battery itself thinner. In some cases, a flexible metal foil such as an aluminum foil or a copper foil is used as an electrode, and the electrode is extended outside the battery case as a flat terminal. Further, the flexible material forming the battery case formed as described above can be obtained by laminating various material layers by a technique such as lamination. For example, as shown in FIG.
a ', 15b', and 15c 'are laminated to form a battery case packaging material 10'. The battery case is required to have physical properties for protecting the battery electromotive section. For example,
A barrier property that blocks the permeation of water vapor and various gases, which is a necessary condition as a packaging material for a battery case, is required.
In the example of FIG. 8, 12 'is the layer used for that purpose. As a material of the layer, a metal foil such as copper is often used as a laminate material of the packaging material because of its excellent barrier properties. Although the layer such as the copper foil has excellent barrier properties, it also has conductivity, and is described as a conductive layer or a barrier layer in the following description. By the way, in each material constituting the packaging material, the outermost layer 11 'forms a battery case with the innermost sealant layer 14' for abrasion resistance of the surface and prevention of pinholes caused by piercing. The reinforcing layer 13 'is a layer laminated for the purpose of further reinforcing the strength of the case. When the battery case C 'is formed using the battery case packaging material 10' as shown in FIG. 8A, the battery case C 'is laminated on the cut surface 1' of the battery case C 'as shown in FIG. 8C. The conductive layer cross section 12 'of the structure may be exposed. In such a case, in the end section 1 'of the case, the conductive terminal P' and the end exposed surface of the conductive layer 12 'in the packaging material have a very close positional relationship. There is a risk that the electrode terminal P 'may be bent and come into contact with the conductive layer 12' exposed on the cross section 1 'of the laminated structure. If the contact trouble occurs before using this battery, such as during storage of the battery, the battery will be discharged and the life of the battery will be exhausted. In addition, when the battery is attached to the target device or during use, if the end conductive layer 12 'of the battery case comes into contact with the electrode terminal P', the device to which the battery is attached does not function. This may cause the device to fail. As a countermeasure for avoiding such contact trouble, there is a method of covering the end section 1 'of the battery case C' with an insulating material. 'Would greatly reduce its processing efficiency. On the other hand, the flat electrode terminal P ′ is easily bent if it is a single metal foil,
There is a problem that the battery case easily comes into contact with the end face cross section 1 'of the battery case.

[0003]

SUMMARY OF THE INVENTION In a battery case formed of a flexible laminate material, a conductive layer is included in the laminate material layer, the conductive layer is exposed at a cross section of an end of the case, and a sheet-like electrode is formed. Provided is a technique for a battery case and an electrode structure that does not cause a short circuit in a battery case and an electrode structure sandwiched between the battery cases.

[0004]

A battery case having a terminal portion of a flat electrode extending from a battery electromotive section to the outside of a battery case, wherein each of the pole terminals at a portion located outside the battery case is provided. An electrode structure of a battery case, wherein terminals of the electrode are covered with an insulating sheet having at least one cutout portion, wherein each of the following inventions includes an inner surface of the battery case and an insulating sheet. The outer surface is heat-sealed, an electrode and a heat-sealable layer are provided on at least one surface of the insulating sheet, and the base material of the insulating sheet is made of polyethylene terephthalate, polyamide, polyimide, or polycarbonate. And the printing is provided on the battery case and / or the insulating sheet.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a thin type of battery among various types of batteries. A battery case is formed using a flexible sheet. The above-mentioned problem has been solved by covering the extended flat terminal with an insulating film, and by providing a notch at a predetermined position of the covering film, connection to a target device is enabled. It is. FIG.
FIGS. 3A and 3B are diagrams illustrating an electrode structure of a battery case according to the invention; FIG. 3A is an overall perspective view of the battery, FIG. (c) it is a sectional view of _{X 1 -X 1 (X 2 -X} 2). FIG. 2 is a perspective view for explaining a method of coating a protective film on an electrode, and shows (a) before coating and (b) after coating.
3, a description will be given of an embodiment of the electrode structure of the battery case of the present invention, a perspective view showing a state before the battery case enclosing the battery body (a) a battery case, (b) X ₂ -X ₂ parts It is sectional drawing. FIG. 4 is a top view of a battery having an electrode structure of a battery case according to the embodiment. FIG. 5 is a cross-sectional view of (a) part X ₃ -X ₃ (X ₄ -X ₄ ) in FIG.
FIG. 6B is an enlarged view of a portion W, and FIG.
(A) Y ₁ -Y ₁ part cross-sectional view, a (b) Y ₂ -Y ₂ parts cross section. FIG. 7 is a cross-sectional view illustrating the material configuration of the electrode protection film of the present invention. FIGS. 8A and 8B illustrate an electrode structure of a battery case according to the related art. FIG. 8A is a cross-sectional view of a layer configuration showing the material of the battery case, FIG. 8B is a perspective view of the battery according to the related art, and FIG. FIG.

As shown in FIGS. 8 (a) and 8 (c), a flexible packaging material 10 'for forming a battery case C is provided.
When a conductive layer 12 ′ such as a metal foil is included therein, the above-mentioned portion in the packaging material 10 ′ is exposed to the end section 1 ′ as the battery case C ′ when forming the case, and If the terminal P 'is in the form of a sheet such as a flexible metal foil, the electrode terminal P' comes into contact with the conductive layer 12 'exposed on the cross section of the battery case C' before or during use of the battery. There is danger. When the contact trouble occurs, the electromotive force decreases due to the discharge of the battery, or the electromotive force becomes zero.
If the contact trouble occurs in the use target device, it may cause a functional failure of the device or a failure of the device. Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problem, and as a result, have been able to solve the problem by changing the structure of the electrode to a structure described below. As shown in FIG. 1, the above-mentioned contact trouble is prevented by covering the lead-out portion of the electrode including the sheet-shaped electrode P, particularly the portion sandwiched by the end of the battery case, with an electrode protection film F having an insulating property. It became possible to prevent. The degree of coverage of the electrode terminals P with the electrode protection film F is not particularly limited, but the entire surface must not be covered to be electrodes. That is, it is necessary to provide an exposed portion exhibiting conductivity (hereinafter, referred to as a contact area) for coming into contact with an input end to a partner device used as a battery. Specifically, when the notch 2 is formed in the electrode protection film F and the electrode protection film F is covered from both sides of the electrode terminal P, the position electrode terminal of the notch 2 is exposed and the battery Is the contact area 3 with the target device. In forming the contact area 3, when bonding the electrode protection film F and the electrode terminal P, an insulating film such as an adhesive is not formed in the contact area 3.

Although the battery case C of the present invention is desirably assembled by a heat sealing technique, the battery case C and the electrode structure thereof which meet the purpose of the present invention can be obtained by other techniques such as using an adhesive. If so, that technique may be used.

[0008] The material of the battery case C used in the present invention is that it can form a sealed system and has a property of preventing water vapor or corrosive gas from the outside from entering the case for an extremely long time. That is, the so-called barrier properties are good, heat resistance and cold resistance are basic thermal conditions, and the outer and innermost materials of the case have insulating properties. Various materials can be considered as the battery case material 10 that satisfies the required physical properties as described above, but it is preferable to use a laminated material obtained by bonding a flexible film or a metal foil. That is, it is possible to make use of the excellent physical properties of the film or the metal foil or the like and, on the contrary, complement the disadvantages of each film or metal foil. The method for forming the case is not particularly limited, and a method using an adhesive, a sealing method using ultrasonic waves, high frequency, or the like, a heat sealing method for bonding by heating and pressing, or the like can be used. In the present invention, it is desirable to form a case by bonding a necessary portion by heat sealing as a heat-sealable material as an inner surface material of the laminated material forming the case.

The laminated material forming the battery case of the present invention will be specifically described. As an example of a specific layer configuration as the laminated material, the following configuration can be adopted as shown in FIG. (Outer) Outermost layer / Barrier layer / Reinforcing layer / Sealant (Inner) layer Each of the above layers can be laminated by dry lamination or sandwich lamination. The total thickness of the above layer structure is preferably 50 to 200 μm. If the total thickness is less than 50 μm, the water vapor barrier property is poor, and there is a risk that moisture may enter the electrolyte. If the total thickness of the above layer configuration exceeds 200 μm, it will deviate from the basic concept of a polymer battery, which wants to be as light and thin as possible, and the effect of a thickness exceeding 200 μm on the barrier properties against water vapor and various gases, etc. Can not expect.

[0010] Each layer of the laminated material in the above example is selected according to its physical properties. The following structure can be used as a specific laminated material. (Outside) PET / AL / PET (or Ny / sealant (inside) [Abbreviation PET: polyethylene terephthalate, AL:
Aluminum (Foil), Ny: Nylon] Since the outermost layer 11 is a surface layer of the battery case, the outermost layer 11 has insulation properties, has a smooth surface, has chemical resistance, has friction resistance, and has tensile strength. It is required to have a function of protecting the battery from various physical and chemical damages or decomposition received from the outside by the battery case, which has strength against piercing or the like. Specific materials are various resins, preferably PE
A biaxially stretched film formed from T is desirable. The thickness of the outermost layer 11 is desirably 5 to 30 μm. When the thickness of the outermost layer 11 is less than 5 μm, the piercing from the outside is inferior and the risk of pinholes is large. When the thickness exceeds 30 μm, the heat sealing property at the time of forming the case is affected.

Preferably, a barrier layer 12 is provided next to the outermost layer 11. The barrier layer 12 is a material for a blocking function (barrier function) for preventing water vapor and various gases from entering or permeating the battery case. Ethylene / vinyl alcohol copolymer, film made of ethylene / vinyl alcohol copolymer, etc., or film of metal or inorganic oxide such as silicon oxide deposited on polyethylene terephthalate film, etc., barrier coating agent such as polyvinylidene chloride May be used, but it is preferable to use a metal such as an aluminum foil to obtain a high barrier. When an aluminum foil is used as the barrier layer 12, its thickness is desirably about 5 to 30 μm. When the thickness of the aluminum foil is less than 5 μm, the number of pinholes is large and the barrier property is poor. When the thickness of the aluminum foil exceeds 30 μm, the heat sealing property at the time of forming the case is affected.

Preferably, a reinforcing layer 13 is provided inside the barrier layer 12. By adding the reinforcing layer 13, the strength of the battery case can be reinforced. In particular, reinforcement against damage to the battery case due to protrusions is desired. As the reinforcing layer 13, a biaxially stretched film, preferably PET
Alternatively, Ny or the like can be used. The thickness of the reinforcing layer 13 is preferably 5 to 30 μm. Reinforcement layer thickness 5μ
If it is less than m, the piercing resistance from the inside (battery main body) is poor, pinholes are easily generated, and electrolyte leakage, delamination and the like may occur. The thickness of the reinforcing layer 13 is 30 μm.
If it exceeds m, the sealability at the time of molding will be affected.

The material of the sealant layer 14 of the laminated material adheres to necessary portions in the formation of the battery case C. As described above, the method of forming the battery case is a bonding method by heat fusion (heat sealing method). However, it is desirable in terms of workability, sealability, and the like. In the case of the heat sealing, it is selected from a resin having a heat-fusing property, but a material which can be heat-fused with an electrode terminal described later or a coating material of the electrode terminal. As the sealant layer 14, a material which can be heat-sealed to the metal foil of the electrode terminal or the covering film of the terminal as described above is used. Specifically, ethylene acrylic acid (EAA), ethylene methacrylic acid (EMAA), ethylene ethyl acrylate (EE
A), ionomers and the like can be used. The sealant layer 14 may be formed by laminating a film formed using the resin in advance on the surface of the reinforcing layer 13 or by extruding the resin on the surface of the reinforcing layer 13 with an extruder. May be used to form a layer.

The thickness is desirably 10 to 100 μm. If the thickness of the sealant layer 14 is less than 10 μm, the piercing resistance from the internal battery body is inferior, pinholes are easily generated, and there is a risk of electrolyte leakage and delamination. Further, when the thickness of the sealant layer 14 exceeds 100 μm, the absolute moisture absorption of the film itself of the sealant layer increases, and the inside of the spout is provided with means for preventing the bag from closing when sucking the contents. There is a risk of ingress of moisture. As described above, the outermost layer 11, the barrier layer 12, the reinforcing layer 13, and the sealant layer 14 may be bonded to each other by dry lamination with a polyurethane-based adhesive or a sandwich in which an adhesive resin is extruded and bonded between the respective layers. Lamination can be performed by a technique such as lamination.

Next, an electrode terminal according to the present invention will be described. The electrode terminal P in the present invention is a flat terminal such as a metal foil, and as described above, the contact area 3, that is, both sides of the terminal except for the connection part to the target device are covered by the electrode protection film F having insulating properties. It is characterized by coating. As an example of the coating method, as shown in FIG. 2A, a notch 2 is provided at a predetermined position of a coating film F, and the coating film F is folded in two. In the example of FIG. The notch 2 is provided so as to coincide with the position to be the contact area 3 of each terminal P, and the electrode terminal P is placed between the folded electrode protection films 2 by a method such as heat sealing. And the electrode terminal P is adhered and covered, and the terminal peripheral portion is heat-fused to the inner surfaces of the electrode protection film F. As a method of bonding at the time of coating on the electrode terminal P, other than the heat sealing method, for example, an adhesive is applied to the inner surface of the electrode protection film P, and the electrode terminal P is immediately coated and kept in a pressurized state for a predetermined time May be adhered.

In the above-mentioned coating, there may be a non-coating portion 7 in the portion near the electromotive portion D of the battery and located in the battery case C. The area located in the area is provided with a sufficient covering area, and the electrode terminal P
Layer 12 of battery case end section 1 due to bending of
So that no contact trouble occurs.

Next, the electrode protection film F covering the electrode terminals P in the present invention will be described. The electrode protection film F may be any as long as it has an insulating property and can be adhered to the surface of the electrode terminal P. As shown in FIG. 7
As shown in FIG. 2B, the support layer 22 and the adhesive layer 21
A support layer 22 as shown in FIG.
May be composed of three layers in which the adhesive layer 21 is laminated on one side and the outer layer 23 is laminated on the side opposite to the adhesive layer. As described above, it is preferable that the battery case be formed by the heat sealing method, but the situation is the same for the coating of the electrode terminals. As a material used for the adhesive layer 21 and the outer layer 23 of the electrode protection film 20, a material that can be thermally fused to a metal foil or the like of an electrode terminal is used. Specifically, ethylene acrylic acid (EA)
A), ethylene methacrylic acid (EMAA), ethylene ethyl acrylate (EEA), ionomer and the like. As the support layer 22, a film or the like that is less likely to expand and contract due to heat and has excellent tensile strength is selected. Specifically, polyethylene terephthalate, polyamide,
A biaxially stretched film made of polyimide or polycarbonate is preferably used.

The electrode of the present invention is a flat plate and is made of a conductive material. Specifically, aluminum, copper,
Examples thereof include a metal such as tin or an alloy of two or more of these metals that has been subjected to foil processing.

The coating with the electrode protection film according to the present invention will be described in more detail. Electrode terminal P of the present invention
The portion is an area exposed as a contact area 3 in order to be connected to the terminal of the target device as the battery T and conduct electricity, but the other part, especially the vicinity of the end section 1 of the battery case is covered with the electrode protection film F. By doing so, it was possible to prevent a problem due to a short circuit between the conductive layer 12 in the case packaging material and the electrode terminal P, which is an object of the present invention. And other parts may or may not be covered,
The electrode portion protruding from the battery case is flexible, and before or after use as a battery, the electrode portion is deformed and causes a poor contact with the target device. It is desirable to cover the electrode terminal surface with the electrode protection film F as much as possible. A specific method of exposing a predetermined part of the electrode terminal P and covering the other part with the electrode protection film F is as shown in FIG. Then, an electrode protection film F exceeding the left and right widths is prepared, and a notch is provided at a predetermined position when the electrode is covered. The electrode terminal portion P exposed by the notch 2 becomes the contact portion 3 of the electrode P as the battery T. The notch 2 may be provided on one side of the electrode, or may be provided on both the front and back surfaces, and may be provided as the notch 2 having an area including the cross section at the tip of the electrode terminal P or both right and left cross sections. Is also good.

In covering the electrode terminal P with the electrode protection film F in the present invention, it is a condition that the conductivity of the contact area 3 of the electrode is maintained. To this end, at least a layer of the electrode protection film P that is bonded to the electrode terminals P is a layer made of a material that can be thermally fused to the terminals P, and is thermally fused after the notch 2 is formed. When an adhesive is applied to the electrode protection film F and bonded to the terminal P, the notch 2 is formed in the electrode protection film F, and then the adhesive is applied to the adhesive layer excluding the notch 2. And then bonded to the electrode terminals P. Most preferably, at least one surface of the electrode protective film F is formed by laminating a material made of a material having heat-fusibility with the electrode terminal P as described above, and after forming the punched portion, An electrode is sandwiched between the surfaces of the heat-sealing layer, and an insulating sheet is coated and adhered to the surface of the electrode terminal by pressurizing and heating.

The electrode structure of the battery case according to the present invention eliminates the trouble caused by the short-circuit between the end section 1 of the battery case C and the electrode terminal P.
The effect of reinforcement of the electrode terminal outside of was observed. Further, the battery case C of the present invention is made of a material having a laminated structure.
It can print usage instructions or precautions for use.
Further, if necessary, printing can be performed on the electrode protection film F. In this case, as the electrode protection film F,
As shown in FIG. 7B or FIG.
By forming a laminated film containing
After printing, the adhesive layer 21 and / or the outer layer 23 are laminated on the printing surface. Each of the printing layers provided in this manner can backprint a film, so that the printed portion is located not between the surface but between the layers, and the printed portion is excellent in abrasion resistance. That is, as ink
In particular, ordinary printing inks that do not require rub resistance can be used.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Outermost layer 1 of packaging material forming battery case C
Polyethylene terephthalate of 12 μm thickness, Lumirror (trade name, manufactured by Toray Industries, Inc.)
Using a two-component polyurethane-based adhesive, an aluminum foil 15 μm (manufactured by Mitsubishi Aluminum Corporation) as the barrier layer 12 was laminated as an intermediate layer. The polyurethane-based adhesive is mainly composed of isocyanate and bamboo rack A5.
11 (trade name, manufactured by Takeda Pharmaceutical Co., Ltd.) and Polyol A50 (trade name, manufactured by Takeda Pharmaceutical Co., Ltd.), and the coating amount as an adhesive was 3 to 5 g / m ² . next,
On the surface of the laminated aluminum foil, a reinforcing layer 13 having a thickness of 12
μm biaxially stretched nylon film and emblem (trade name, manufactured by Unitika Ltd.) are laminated by a dry lamination method using the same polyurethane adhesive as described above, and ethylene methacrylic acid ( EEA) and Nuclell (trade name, manufactured by Mitsui Polychemicals, Inc.) were laminated to a thickness of 50 μm by an extrusion method.

Separately, as the electrode protection film F, 12 μm
Polyethylene terephthalate film, Lumirror (trade name, manufactured by Toray Industries, Inc.), on both surfaces of which ethylene methacrylic acid (EE
A) and Nuclel (trade name, manufactured by Mitsui Polychemicals, Inc.) were formed on both surfaces of the polyethylene terephthalate film by an extrusion method to a thickness of 20 μm.

Next, using a laminated packaging material F for the battery case, to form a bag C ₀ of pillow type having an opening 6, as shown in FIG. 3 (a).

The electrode terminal P extended from the electromotive section D is a copper foil of 40 μm, the width of both plus and minus terminals is 15 mm, and the length is 30 mm. The formation of the notch 2 in the electrode protection film and the coating on the electrode terminal P were performed by the method shown in FIG. Next, FIG.
(A) Inserting the battery body covered with the electrode protection film F into the battery electromotive part D and the electrode terminal P extended from the electromotive part D from the open part 6, and the electrode terminal part covered with the electrode protection film F , And the open portion was heat-sealed to obtain a polymer battery T shown in FIG. 4 as a top view thereof. In the present embodiment, the notch 2 (which becomes a contact portion as an electrode) has an elliptical shape, and both the positive electrode and the negative electrode are provided on both surfaces. The electrode structure of the battery case of the obtained polymer battery T is such that, as shown in FIGS. 5 and 6, the contact part 3 of the battery terminal is provided at a position near the tip of the terminal P, Are covered with the insulating electrode protection film F, so that there is no trouble due to a short circuit as in the prior art.

According to the electrode structure of the battery case covered with the electrode protection film F of the present embodiment, the electrode terminal portion P is not short-circuited even if it is bent as described above. As a reinforcing effect.

[0027]

As described above, the metal foil of the laminated material constituting the battery case and the electrode are not short-circuited, and a stable case and electrode can be provided. By covering the electrode with the insulating sheet, the rigidity of the electrode terminal portion extending from the end face of the battery case to the front is improved, and the terminal is not bent when used as a battery, and the use stability is improved. Got well.

[Brief description of the drawings]

1A and 1B are diagrams illustrating an electrode structure of a battery case according to the present invention, wherein FIG. 1A is an overall perspective view of a battery, and FIG. 1B is a perspective view of an electromotive section and an electrode terminal of the battery. Cross-sectional view of (c) X ₁ -X ₁ (X ₂ -X ₂ )

FIG. 2 is a perspective view illustrating a method for coating an electrode with a protective film, and shows (a) before coating and (b) after coating.

3 (a) is a perspective view showing a state of a battery case before enclosing a battery body of the battery case, and FIG. 3 (b) is a section X ₂ -X ₂ illustrating an embodiment of an electrode structure of the battery case of the present invention. Sectional view

FIG. 4 is a top view of a battery having an electrode structure of a battery case according to the embodiment.

FIG. 5 shows (a) X ₃ −X ₃ (X ₄ −
X ₄ ) section sectional view, (b) W section enlarged view

FIG. 6 is a sectional view of (a) Y ₁ -Y ₁ part in FIG. 4;
(B) Y ₂ -Y ₂ parts cross section

FIG. 7 is a cross-sectional view illustrating a material configuration of the electrode protection film of the present invention.

8 (a) is a cross-sectional view of a layer structure showing a material of a battery case, illustrating an electrode structure of a battery case according to the related art.
(B) A perspective view of a battery according to the prior art, and (c) an enlarged view as viewed from the arrow Z.

[Explanation of symbols]

 T (Polymer) Battery C Battery Case D Electromotive Part P Electrode Terminal F Electrode Protection Film 1 End Section of Battery Case 2 Notch 3 Contact Area 4 Heat Sealing Part 5 Back Paste Part 6 Battery Body Insertion Part 7 Uncovered Part 10 Packaging material for battery case 11 Outermost layer 12 Conductive layer (barrier layer) 13 Reinforcement layer 14 Sealant layer 15 Adhesive layer 20 Electrode protective film 21 Adhesive layer of electrode protective film to electrode (adhesive layer) 22 Electrode protective film support layer (Support layer) 23 Outer layer (outer layer) of electrode protection film

Claims (5)

[Claims] 1. A battery case having a terminal portion of a flat electrode extending from a battery electromotive portion and reaching the outside of a battery case, wherein at least one terminal is provided for each pole terminal at a portion located outside the battery case. An electrode structure for a battery case, wherein the terminals of the electrode are covered with an electrode protection film having an insulating property and provided with cutout portions. 2. The electrode structure of a battery case, wherein an inner surface of the battery case and an outer surface of the electrode protection film are heat-sealed. 3. The electrode structure of a battery case according to claim 1, wherein a layer that can be thermally fused to the electrode is provided on at least one surface of the electrode protection film. 4. The electrode structure of a battery case according to claim 1, wherein the support layer of the electrode protection film is made of polyethylene terephthalate, polyamide, polyimide, or polycarbonate. 5. The electrode structure of a battery case according to claim 1, wherein printing is provided on the battery case and / or the electrode protection film.