Battery, manufacturing method thereof, metal terminal with adhesive film for metal terminal, and roll of adhesive film for metal terminal

Abstract

To provide a battery appropriately suppressing opening of a packaging material in a portion, where an adhesive film is positioned, even in a case where an internal pressure of the battery rises.SOLUTION: The present invention relates to a battery comprising at least: a battery element including a cathode, an anode and an electrolyte; a packaging material sealing the battery element; and a metal terminal respectively electrically connected to the cathode and the anode and extending outside the packaging material. In the battery, an adhesive film for metal terminal is disposed between the metal terminal and the packaging material. The adhesive film for metal terminal successively comprises a first polyolefin layer, a substrate film containing polyethylene-naphthalate, and a second polyolefin layer. At least one of the first polyolefin layer and the second polyolefin layer contains acid-modified polyolefin. An angle θ formed from a direction Ymax which is a maximum intra-plane orientation direction of a naphthalene ring contained in the substrate film and a direction in which the metal terminal extends outside the packaging material is 45° or more and 135° or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a battery, a method for producing the same, a metal terminal with an adhesive film for a metal terminal, and a roll of the adhesive film for a metal terminal. [Background technology]

[0002] Various types of batteries have been developed, and packaging materials are essential components for sealing battery elements such as electrodes and electrolytes in all batteries. Metal packaging materials have traditionally been widely used for battery packaging. However, in recent years, with the increasing performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, and the like, batteries are required to have a variety of shapes, as well as to be thinner and lighter. However, the metal packaging materials that have traditionally been widely used have the drawbacks of being difficult to accommodate the diverse shapes and also having limitations on how light they can be.

[0003] Therefore, in recent years, a film-like laminate in which a base layer, a barrier layer, and a heat-sealable resin layer are sequentially laminated has been proposed as a packaging material that can be easily processed into various shapes and can be made thinner and lighter (see, for example, Patent Document 1). When using such a film-like packaging material, the battery element is sealed with the packaging material by heat-sealing the peripheral portion of the packaging material with the heat-sealable resin layers located in the innermost layers of the packaging material facing each other. Metal terminals protrude from the heat-sealed portion of the packaging material, and the battery element sealed with the packaging material is electrically connected to the outside through the metal terminals electrically connected to the electrodes of the battery element. That is, in the heat-sealed portion of the packaging material, the metal terminals are sandwiched between the heat-sealable resin layers and are formed so as to protrude outside the packaging material. Because the metal terminals and the heat-sealable resin layer are made of different materials, the hermeticity of the battery element is likely to be reduced at the interface between the metal terminals and the heat-sealable resin layer. For this reason, a technique is known in which an adhesive film is disposed at the interface between the metal terminal and the heat-sealable resin layer to prevent a decrease in the sealing property at the interface between the metal terminal and the heat-sealable resin layer.

[0004] For example, Patent Document 2 discloses an adhesive film for sealing metal terminals of lithium batteries, which comprises a biaxially oriented polyethylene naphthalate film on both sides of which an acid-modified polyolefin layer is formed via an adhesion promoter layer made of an isocyanate component. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-202927 [Patent Document 2] Patent No. 4440573 Summary of the Invention [Problem to be solved by the invention]

[0006] The adhesive film disclosed in Patent Document 2 uses a biaxially oriented polyethylene naphthalate film, which has high water vapor barrier properties and mechanical strength, as a substrate, with polyolefin layers laminated on both sides of the substrate via adhesion promoter layers. Therefore, by sealing the metal terminal and the heat-sealable resin layer of the packaging material via the adhesive film, the adhesion between the metal terminal and the heat-sealable resin layer is improved, and short-circuiting between the metal terminal and the barrier layer laminated on the packaging material can be prevented. Furthermore, the use of a biaxially oriented polyethylene naphthalate film has the advantage of excellent heat resistance.

[0007] In recent years, the applications of batteries have become more diverse. For example, batteries used in high-temperature environments or with certain types of electrolytes can increase the internal pressure of the battery's packaging material. For example, when a battery is exposed to high temperatures, the organic solvent used in the electrolyte can decompose, generating gas and causing an increase in internal pressure. Furthermore, charging due to overvoltage or discharging due to excessive current can cause a sustained increase in the temperature inside the battery, leading to a runaway battery reaction and an increase in the internal pressure of the packaging material.

[0008] After extensive research, the inventors discovered that when the internal pressure of the battery packaging material increases, force is applied in the thickness direction of the adhesive film located between the packaging material and the metal terminal, and there is a risk that the heat-sealed portion around the periphery of the battery will open in the area where the adhesive film is located.

[0009] Under these circumstances, the main object of the present invention is to provide a battery in which opening of the packaging material at the portion where the adhesive film is located is suitably prevented even when the internal pressure of the battery increases, and a further object of the present invention is to provide a method for manufacturing the battery. [Means for solving the problem]

[0010] The present inventors have conducted extensive research to solve the above-mentioned problems. As a result, they have found that a battery having the following configuration suitably prevents opening of the packaging material at the portion where the adhesive film is located, even when the internal pressure of the battery increases. The present invention was completed through further research based on this finding.

[0011] A battery comprising: a battery element including at least a positive electrode, a negative electrode, and an electrolyte; a packaging material for sealing the battery element; and metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and extending outside the packaging material, an adhesive film for a metal terminal is disposed between the metal terminal and the packaging material; The adhesive film for a metal terminal includes a first polyolefin layer, a base film containing polyethylene naphthalate, and a second polyolefin layer in this order; At least one of the first polyolefin layer and the second polyolefin layer contains an acid-modified polyolefin, Y, measured by the following method max and a direction in which the metal terminal extends outside the packaging material, the angle θ between the direction in which the metal terminal extends outside the packaging material is 45° or more and 135° or less.

[0012] (Y max (Method of measuring direction) Adhesive film for metal terminals Y max The direction was measured by polarization measurement of the single-reflection ATR method of Fourier transform infrared spectroscopy. When infrared absorption spectra were obtained in 18 directions at intervals of 10° from 0° to 170° in the direction perpendicular to the thickness direction for the surface of the base film, the 765 cm -1 Absorption peak intensity Y at 765 1181cm -1 Absorption peak intensity Y at 1181 The maximum Y value is calculated by dividing by max The direction in which max The direction.

[0013] That is, the present invention provides the following aspects. Item 1. A battery comprising at least a battery element having a positive electrode, a negative electrode, and an electrolyte, a packaging material that seals the battery element, and metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and that extend outside the packaging material, an adhesive film for a metal terminal is disposed between the metal terminal and the packaging material; The adhesive film for a metal terminal includes a first polyolefin layer, a base film containing polyethylene naphthalate, and a second polyolefin layer in this order; At least one of the first polyolefin layer and the second polyolefin layer contains an acid-modified polyolefin, Y, measured by the following method max and a direction in which the metal terminal extends outside the packaging material, the angle θ between the direction in which the metal terminal extends outside the packaging material is 45° or more and 135° or less. Y max The direction was measured by polarization measurement of the single-reflection ATR method of Fourier transform infrared spectroscopy. When infrared absorption spectra were obtained in 18 directions at intervals of 10° from 0° to 170° in the direction perpendicular to the thickness direction for the surface of the base film, the 765 cm -1 Absorption peak intensity Y at 765 1181cm-1 Absorption peak intensity Y at 1181 The maximum Y value is calculated by dividing by max The direction in which max The direction. Item 2. The battery according to Item 1, wherein the thickness of the substrate film of the adhesive film for metal terminals is 10 μm or more and 50 μm or less. Item 3. The battery according to Item 1 or 2, wherein the first polyolefin layer and the second polyolefin layer of the adhesive film for metal terminal contain an acid-modified polyolefin. Item 4. The battery according to any one of Items 1 to 3, wherein the thickness of the first polyolefin layer and the second polyolefin layer of the adhesive film for a metal terminal is 5 μm or more and 80 μm or less. Item 5. The battery according to any one of Items 1 to 4, wherein the adhesive film for a metal terminal has a thickness of 20 μm or more and 200 μm or less. Item 6. The battery according to any one of Items 1 to 5, wherein the packaging material is composed of a laminate including at least a base layer, a barrier layer, and a heat-sealable resin layer in this order. Item 7. A method for manufacturing a battery comprising: a battery element including at least a positive electrode, a negative electrode, and an electrolyte; a packaging material for sealing the battery element; and metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding outside the packaging material, and disposing an adhesive film for metal terminals between the metal terminals and the packaging material, The adhesive film for a metal terminal includes a first polyolefin layer, a base film containing polyethylene naphthalate, and a second polyolefin layer in this order, At least one of the first polyolefin layer and the second polyolefin layer contains an acid-modified polyolefin, Y, measured by the following method max a packaging material in which the angle θ between the direction of the metal terminal and the direction in which the metal terminal extends outside the packaging material is 45° or more and 135° or less. Y maxThe direction was measured by polarization measurement of the single-reflection ATR method of Fourier transform infrared spectroscopy. When infrared absorption spectra were obtained in 18 directions at intervals of 10° from 0° to 170° in the direction perpendicular to the thickness direction for the surface of the base film, the 765 cm -1 Absorption peak intensity Y at 765 1181cm -1 Absorption peak intensity Y at 1181 The maximum Y value is calculated by dividing by max The direction in which max The direction. Item 8. A metal terminal with an adhesive film for a metal terminal, in which an adhesive film for a metal terminal is attached to the metal terminal of a battery, The adhesive film for a metal terminal includes a first polyolefin layer, a base film containing polyethylene naphthalate, and a second polyolefin layer in this order; At least one of the first polyolefin layer and the second polyolefin layer contains an acid-modified polyolefin, The direction in which the metal terminal extends outward from the battery when attached to the battery and the Y of the adhesive film for metal terminals measured by the following method. max The metal terminal with the adhesive film for metal terminal, wherein the adhesive film for metal terminal is attached to the metal terminal so that the angle θ formed with the direction is 45° or more and 135° or less. Y max The direction was measured by polarization measurement of the single-reflection ATR method of Fourier transform infrared spectroscopy. When infrared absorption spectra were obtained in 18 directions at intervals of 10° from 0° to 170° in the direction perpendicular to the thickness direction for the surface of the base film, the 765 cm -1 Absorption peak intensity Y at 765 1181cm -1 Absorption peak intensity Y at 1181 The maximum Y value is calculated by dividing by max The direction in which max The direction. Item 9. A roll of adhesive film for metal terminals, which is interposed between metal terminals electrically connected to the positive and negative electrodes of a battery element having at least a positive electrode, a negative electrode, and an electrolyte, and a packaging material that seals the battery element, The adhesive film for a metal terminal includes a first polyolefin layer, a base film containing polyethylene naphthalate, and a second polyolefin layer in this order; At least one of the first polyolefin layer and the second polyolefin layer contains an acid-modified polyolefin, Y, measured by the following method max A roll of adhesive film for a metal terminal, wherein the angle θ formed by the winding direction and a direction perpendicular to the winding direction of the roll of adhesive film for a metal terminal is 45° or more and 135° or less. Y max The direction was measured by polarization measurement of the single-reflection ATR method of Fourier transform infrared spectroscopy. When infrared absorption spectra were obtained in 18 directions at intervals of 10° from 0° to 170° in the direction perpendicular to the thickness direction for the surface of the base film, the 765 cm -1 Absorption peak intensity Y at 765 1181cm -1 Absorption peak intensity Y at 1181 The maximum Y value is calculated by dividing by max The direction in which max The direction. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a battery in which opening of the packaging material at the portion where the adhesive film is located is suitably prevented even when the internal pressure of the battery increases. Furthermore, according to the present invention, it is also possible to provide a method for manufacturing the battery, and a metal terminal with an adhesive film for a metal terminal. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic plan view of a battery of the present invention. [Figure 2]FIG. 2 is a schematic cross-sectional view taken along line AA' in FIG. [Figure 3] FIG. 2 is a schematic cross-sectional view taken along line BB' in FIG. [Figure 4] 1 is a schematic cross-sectional view of an adhesive film for a metal terminal used in a battery of the present invention. [Figure 5] 1 is a schematic cross-sectional view of a packaging material used in a battery of the present invention. [Figure 6] FIG. 2 is a schematic diagram illustrating the fabrication of a test battery. [Figure 7] This is a schematic diagram to explain the angle θ between the Ymax direction, which is the maximum in-plane orientation direction of the naphthalene rings contained in the base film of the adhesive film for metal terminals, and the direction in which the metal terminal extends outside the packaging material. [Figure 8] FIG. 1 is a schematic diagram for explaining an opening test of a packaging material. [Figure 9] 1 is a schematic diagram of a metal terminal with an adhesive film for a metal terminal of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] The battery of the present invention is a battery comprising at least a battery element having a positive electrode, a negative electrode, and an electrolyte, a packaging material that seals the battery element, and metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and extend outside the packaging material.

[0017] In the battery of the present invention, an adhesive film for metal terminals is disposed between the metal terminals and the packaging material, and the adhesive film for metal terminals comprises a first polyolefin layer, a substrate film containing polyethylene naphthalate, and a second polyolefin layer in this order, and at least one of the first polyolefin layer and the second polyolefin layer contains an acid-modified polyolefin.

[0018] Furthermore, in the battery of the present invention, the Y max The angle θ between the direction of the metal terminal and the direction of the metal terminal extending outside the packaging material is 45° or more. It is characterized by being 135° or less.

[0019] (Y max (Method of measuring direction) Adhesive film for metal terminals Y max The direction is measured by a single Fourier transform infrared spectroscopy When infrared absorption spectra were obtained for the surface of the substrate film in 18 directions at intervals of 10° from 0° to 170° in a direction perpendicular to the thickness direction by polarization measurement using a reflection ATR method, the 765 cm -1 Absorption peak intensity Y at 765 1181cm -1 Absorption peak intensity Y at 1181 The maximum Y value is calculated by dividing by max The direction in which max The direction.

[0020] The battery of the present invention and the method for producing the same will be described in detail below.

[0021] In this specification, a numerical range indicated by "to" means "greater than or equal to" or "less than or equal to." For example, the expression 2 to 15 mm means 2 mm or greater and 15 mm or less.

[0022] The battery 10 of the present invention comprises at least a battery element 4 having a positive electrode, a negative electrode, and an electrolyte, a packaging material 3 that seals the battery element 4, and metal terminals 2 that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude outside the packaging material 3. In the battery 10 of the present invention, an adhesive film 1 for a metal terminal, which will be described later, is disposed between the metal terminal 2 and the packaging material 3. That is, the battery 10 of the present invention can be produced by a method that includes a step of disposing the adhesive film 1 for a metal terminal between the metal terminal 2 and the packaging material 3. In the production of the battery of the present invention, the adhesive film 1 for a metal terminal is provided with a Y max The angle θ between the direction of the terminal and the direction in which the metal terminal extends outside the packaging material is 45° or more and 135° or less.

[0023] Specifically, when a battery element 4 including at least a positive electrode, a negative electrode, and an electrolyte is sealed with a packaging material 3, an adhesive film for metal terminals 1 is interposed between the metal terminals 2 and the heat-sealable resin layer 35 with the metal terminals 2 protruding outward. At this time, the adhesive film for metal terminals 1 is disposed between the metal terminals 2 and the packaging material 3 so that the angle θ is 45° or more and 135° or less. Then, the heat-sealable resin layers 35 of the flange portions are heat-sealed together so that a flange portion of the packaging material 3 (a region where the heat-sealable resin layers 35 contact each other, i.e., the peripheral portion 3a of the packaging material) can be formed around the periphery of the battery element 4, and the battery element 4 is sealed with the packaging material 3, thereby obtaining a battery.

[0024] In the battery 10 of the present invention, a metal terminal 5 with an adhesive film for a metal terminal, in which an adhesive film for a metal terminal 1 is attached to a metal terminal 2 in advance, may be disposed between the upper and lower packaging materials 3. The metal terminal 5 with an adhesive film for a metal terminal has a direction x in which the metal terminal 2 extends outward from the battery when attached to the battery (the direction x corresponding to the direction in which the metal terminal extends outward from the packaging material described above) and a direction x in which the adhesive film for a metal terminal extends outward from the battery when attached to the battery. max The adhesive film 1 for a metal terminal is attached to the metal terminal 2 so that the angle θ between the direction is 45° or more and 135° or less (see FIG. 9). The present invention can also provide such a metal terminal with an adhesive film for a metal terminal.

[0025] The battery of the present invention may be either a primary battery or a secondary battery, but is preferably a secondary battery. The type of secondary battery is not particularly limited, and examples include lithium ion batteries, lithium ion polymer batteries, lead acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, metal-air batteries, polyvalent cation batteries, condensers, and capacitors. Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries are preferred.

[0026] Adhesive film for metal terminals The adhesive film for metal terminals used in the battery of the present invention will be described in detail below.

[0027] The adhesive film for a metal terminal is disposed between a metal terminal electrically connected to an electrode of a battery element and a packaging material that seals the battery element. Specifically, as shown in Figures 1 to 3, for example, the adhesive film for a metal terminal 1 is disposed between a metal terminal 2 electrically connected to an electrode of a battery element 4 and a packaging material 3 that seals the battery element 4. The metal terminal 2 protrudes outside the packaging material 3 and is sandwiched between the packaging material 3 at a peripheral edge 3a of the heat-sealed packaging material 3 via the adhesive film for a metal terminal 1. In the present invention, the heating temperature when heat-sealing the packaging material is typically in the range of about 160 to 190°C, and the pressure is typically in the range of about 1.0 to 2.0 MPa.

[0028] The adhesive film 1 for metal terminals is provided to improve the adhesion between the metal terminal 2 and the packaging material 3. Improved adhesion between the metal terminal 2 and the packaging material 3 improves the hermetic sealing of the battery element 4. As described above, when the battery element 4 is heat-sealed, the battery element is sealed so that the metal terminal 2 electrically connected to the electrode of the battery element 4 protrudes outside the packaging material 3. At this time, the metal terminal 2 made of metal and the heat-sealable resin layer 35 (a layer made of a heat-sealable resin such as polyolefin) located in the innermost layer of the packaging material 3 are made of different materials. Therefore, without using such an adhesive film, the hermetic sealing of the battery element is likely to be poor at the interface between the metal terminal 2 and the heat-sealable resin layer 35.

[0029] In the present invention, the adhesive film 1 for a metal terminal comprises a first polyolefin layer 12a, a base film 11, and a second polyolefin layer 12b in that order, with at least one of the first polyolefin layer 12a and the second polyolefin layer 12b being formed from an acid-modified polyolefin. In the adhesive film 1 for a metal terminal, the first polyolefin layer 12a and the second polyolefin layer 12b are located on both surfaces, respectively. When the adhesive film 1 for a metal terminal is placed between the metal terminal 2 of the battery 10 of the present invention and the packaging material 3, the surface of the metal terminal 2 made of metal and the heat-sealable resin layer 35 of the packaging material 3 (a layer formed from a heat-sealable resin such as polyolefin) are bonded via the adhesive film 1 for a metal terminal.

[0030] As will be described later, in the battery of the present invention, as shown in the schematic diagram of FIG. 7, the maximum in-plane orientation direction of the naphthalene rings contained in the base film 11 of the adhesive film for metal terminal 1 is Y max The heat-sealable resin layers 35 of the packaging material 3 are heat-sealed together with the adhesive film 1 for metal terminals disposed between the metal terminals 2 and the packaging material 3 so that the angle θ between the direction x in which the metal terminals 2 extend outward from the packaging material 3 is 45° or more and 135° or less. This effectively prevents opening of the heat-sealed portion of the periphery of the battery where the adhesive film for metal terminals is located, even if the internal pressure of the battery increases. That is, by the angle θ being 45° or more and 135° or less, the maximum in-plane orientation direction of the naphthalene rings contained in the base film 11, Y max The direction of the naphthalene rings is nearly perpendicular to the direction x in which the metal terminals 2 extend outward from the packaging material 3. This orientation of the naphthalene rings increases the strength of the base film 11 in the direction x. Therefore, even when the internal pressure of the battery increases and a strong force is applied from inside the battery in the direction x, the base film 11 is less likely to undergo cohesive failure, and it is possible to suitably prevent the opening of the heat-sealed portion around the battery.

[0031] [Base film 11] In the adhesive film 1 for a metal terminal, the base film 11 is a layer that functions as a support for the adhesive film 1 for a metal terminal.

[0032] The substrate film 11 contains polyethylene naphthalate (PEN). As disclosed in Patent Document 2, for example, PEN has a higher melting point and glass transition point than polyethylene terephthalate (PET), polyolefin, acid-modified polyolefin, etc., and has excellent mechanical strength at high temperatures. Therefore, even when the adhesive film for metal terminal 1 is heat-sealed while sandwiched between the metal terminal 2 and the packaging material 3, the PEN film is less likely to become thin. Furthermore, PEN has a lower water vapor permeability than PET, and is excellent in water vapor barrier properties.

[0033] As long as the base film 11 contains polyethylene naphthalate (PEN), it may further contain other resins, such as polyesters other than PEN, epoxy resins, acrylic resins, fluororesins, silicone resins, phenolic resins, polyetherimide resins, polyimide resins, polycarbonates, and mixtures or copolymers thereof.

[0034] Specific examples of polyester resins different from PEN include polyethylene terephthalate, polybutylene terephthalate, polybutylene naphthalate, polyethylene isophthalate, copolymer polyesters whose repeating units are mainly ethylene terephthalate, copolymer polyesters whose repeating units are mainly butylene terephthalate, etc. Specific examples of copolymer polyesters whose repeating units are mainly ethylene terephthalate include copolymer polyesters in which ethylene terephthalate is the main repeating unit and is polymerized with ethylene isophthalate (hereinafter abbreviated as polyethylene (terephthalate / isophthalate)), polyethylene (terephthalate / isophthalate), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sodium sulfoisophthalate), polyethylene (terephthalate / sodium isophthalate), polyethylene (terephthalate / phenyl-dicarboxylate), polyethylene (terephthalate / decanedicarboxylate), etc. Specific examples of copolymer polyesters containing butylene terephthalate as the main repeating unit include copolymer polyesters in which butylene terephthalate is the main repeating unit and is polymerized with butylene isophthalate (hereinafter abbreviated as polybutylene (terephthalate / isophthalate)), polybutylene (terephthalate / adipate), polybutylene (terephthalate / sebacate), polybutylene (terephthalate / decanedicarboxylate), polybutylene naphthalate, etc. Polyesters different from PEN may be used alone or in combination of two or more.

[0035] In the present invention, from the viewpoint of providing excellent sealing properties (water vapor barrier properties) between the packaging material and the metal terminal, the base film 11 is preferably made of a polyethylene naphthalate (PEN) film.

[0036] The base film 11 is uniaxially or biaxially stretched. The biaxially stretched base film 11 is preferably used as the base film 11 because its heat resistance is improved by oriented crystallization.

[0037] Furthermore, in the battery of the present invention, the maximum in-plane orientation direction of the naphthalene rings contained in the base film 11 of the adhesive film for metal terminal 1 is Y max direction, and the metal terminal 2 is The adhesive film 1 for metal terminals is arranged so that the angle θ between the direction x in which the adhesive film 1 for metal terminals extends and the direction x in which the adhesive film 1 for metal terminals extends is 45° or more and 135° or less, and the strength of the base film 11 of the adhesive film 1 for metal terminals in the direction x is increased against the force applied when the internal pressure of the battery increases. Therefore, even when the internal pressure of the battery increases and a strong force is applied from inside the battery in the direction x, the base film 11 is less likely to undergo cohesive failure, making it possible to suitably prevent the packaging material from being opened. max The direction is measured as follows.

[0038] <Maximum in-plane orientation direction of naphthalene rings (Y max Direction) Measurement Using polarization measurement by single-reflection ATR in Fourier transform infrared spectroscopy (FT-IR), infrared absorption spectra are obtained for the surface of the substrate film in 18 directions perpendicular to the thickness direction, from 0° (an arbitrary reference direction perpendicular to the thickness direction) to 170° in 10° increments. Here, the surface of the substrate film is the surface on which either the first polyolefin layer or the second polyolefin layer is laminated. Next, in each of these 18 directions, the 765 cm of the infrared absorption spectrum is measured. -1 Absorption peak intensity Y at 765 1181cm -1 Absorption peak intensity Y at 1181 Then, the maximum value Y among the obtained values ​​Y (18 values) is calculated. max The direction in which maxThe infrared absorption spectrum is measured under the following conditions, for example: For the adhesive film for metal terminal obtained from the battery, the maximum in-plane orientation direction (Y max When measuring the maximum in-plane orientation direction (Y ) of the naphthalene rings on the surface of the substrate film, first, the peripheral heat-sealed portion with the metal terminal interposed therebetween is cut off, the battery packaging material is removed, and the adhesive film for metal terminals is separated from the battery. Next, the first polyolefin layer or the second polyolefin layer is peeled off and removed to expose the substrate film, and measurements can be made in this state. In addition, for the adhesive film for metal terminals obtained from the adhesive film for metal terminals heat-sealed to the metal terminal, the maximum in-plane orientation direction (Y ) of the naphthalene rings on the surface of the substrate film can be measured. max When measuring the surface orientation (orientation), the adhesive film for metal terminals can be physically separated from the metal terminal, and the first or second polyolefin layer can be peeled off to expose the substrate film. When peeling off the first or second polyolefin layer from the adhesive film for metal terminals, the first or second polyolefin can be dissolved using a solvent such as heated xylene to expose the substrate film. The surface orientation degree of the substrate film is an indicator of the stretched state of the substrate film, so the measured value is the same whether it is measured after obtaining the substrate film or after peeling off the first or second polyolefin layer from the adhesive film for metal terminals obtained from a battery to expose the substrate film. The surface orientation degree of the substrate film can also be measured after obtaining the substrate film.

[0039] (Infrared absorption spectrum measurement conditions) Spectrometer: Thermo IS10 Attachment: Single reflection ATR attachment (Seagull) Detector: MCT (Hg Cd Te) Resolution: 8cm -1 IRE:Ge Incident angle: 30° Polarizer: Wire grid, S polarization Baseline: 1800cm -1 From 2000cm -1 Average intensity at Absorption peak intensity Y 765 :760cm -1 From 770cm -1 The maximum peak intensity in the range minus the baseline value Absorption peak intensity Y 1181 :1176cm -1 From 1186cm -1 The maximum peak intensity in the range minus the baseline value

[0040] In the battery of the present invention, the maximum in-plane orientation direction of the naphthalene ring contained in the base film 11 of the adhesive film for metal terminal 1 is Y max The mechanism by which opening of the packaging material at the portion where the adhesive film is located is suitably prevented even when the internal pressure of the battery increases when the angle θ between the direction x in which the metal terminal 2 extends outward from the packaging material 3 is between 45° and 135° can be considered as follows. That is, as described above, when the internal pressure of the battery packaging material increases, a large force is applied from the inside to the outside of the battery. At this time, there is a risk that the packaging material will open at the portion where the adhesive film for metal terminals is located between the metal terminals and the packaging material. After further investigation into this point, it was found that when the substrate film of the adhesive film for metal terminals contains polyethylene naphthalate, when force is applied in the direction x in which the metal terminals 2 extend outward from the packaging material 3, the substrate film of the adhesive film for metal terminals is easily peeled off in layers, causing the substrate film of the adhesive film for metal terminals to break and leading to opening of the battery. This is thought to be because the naphthalene rings contained in the base film are oriented in the stretching direction (i.e., perpendicular to the thickness direction) due to the stretching during the production of the base film, resulting in directions of high strength and directions of low strength in the base film, and when the direction of low strength of the base film approaches the direction x, the base film becomes more likely to peel off in layers.

[0041] Further investigations by the present inventors have revealed that when an adhesive film for a metal terminal is placed between the metal terminal and the packaging material, by using a base film in which the angle θ is 45° or more and 135° or less, the maximum in-plane orientation direction of the naphthalene ring, Y max It was confirmed that the direction of the insulating film 100 and the direction x in which the metal terminal 2 extends outward from the packaging material 3 are nearly perpendicular to each other, and that the destruction of the base film in the x direction is effectively suppressed. -1 Absorption peak intensity Y at 765 is due to the out-of-plane vibration of the CH group, and is observed at 1181 cm in the infrared absorption spectrum. -1 Absorption peak intensity Y at 1181 is due to the vibration of the naphthalene ring.

[0042] From the viewpoint of more effectively preventing opening of the packaging material at the portion where the adhesive film is located, in the battery of the present invention, max The lower limit of the angle θ between the Y direction and the direction x is preferably about 50° or more, and the upper limit is preferably about 130° or less, more preferably about 120° or less, and even more preferably about 90° or less. max Preferred ranges of the angle θ between the direction x and the direction x include about 50 to 130°, about 50 to 120°, about 50 to 90°, about 60 to 130°, about 60 to 120°, and about 60 to 90°. The direction x in which the metal terminal extends outside the packaging material is usually the longitudinal direction of the metal terminal.

[0043] If necessary, the surface of the base film 11 may be subjected to a known adhesion-facilitating treatment such as corona discharge treatment, ozone treatment, or plasma treatment.

[0044] The thickness of the base film 11 is not particularly limited, and is preferably about 10 to 50 μm, more preferably about 10 to 30 μm, from the viewpoint of preventing short circuits while providing excellent sealing between the packaging material and the metal terminal.

[0045] [First and second polyolefin layers 12a, 12b] In the adhesive film for metal terminals 1, at least one of the first and second polyolefin layers 12a, 12b is formed from an acid-modified polyolefin. In other words, in the present invention, one of the first and second polyolefin layers 12a, 12b may be formed from an acid-modified polyolefin and the other from a polyolefin, or both the first and second polyolefin layers 12a, 12b may be formed from an acid-modified polyolefin. Acid-modified polyolefins have a high affinity with metals and heat-sealable resins such as polyolefins. Furthermore, polyolefins have a high affinity with heat-sealable resins such as polyolefins. Therefore, by arranging a layer formed from an acid-modified polyolefin on the metal terminal 2 side, excellent adhesion can be achieved at the interface between the adhesive film for metal terminals 1 and the metal terminal 2 and the heat-sealable resin layer 35.

[0046] The adhesive film 1 for metal terminals may be any laminate having a first polyolefin layer 12a, a base film 11, and a second polyolefin layer 12b in that order, and for example, as shown in Figure 4, has a laminate structure in which the first polyolefin layer 12a / base film 11 / second polyolefin layer 12b are laminated in that order.

[0047] In the first and second polyolefin layers 12a and 12b, the acid-modified polyolefin is not particularly limited as long as it is an acid-modified polyolefin, but preferred examples include polyolefins graft-modified with an unsaturated carboxylic acid or anhydride thereof.

[0048] Specific examples of acid-modified polyolefins include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous polypropylenes such as homopolypropylene, polypropylene block copolymers (e.g., propylene-ethylene block copolymers), and polypropylene random copolymers (e.g., propylene-ethylene random copolymers); and ethylene-butene-propylene terpolymers. Among these polyolefins, polyethylene and polypropylene are preferred.

[0049] The acid-modified polyolefin may be a cyclic polyolefin. For example, a carboxylic acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a cyclic polyolefin by substituting an α,β-unsaturated carboxylic acid or an anhydride thereof for some of the monomers constituting the cyclic polyolefin, or by block polymerizing or graft polymerizing an α,β-unsaturated carboxylic acid or an anhydride thereof with a cyclic polyolefin.

[0050] The acid-modified cyclic polyolefin is a copolymer of an olefin and a cyclic monomer, and examples of the olefin constituting the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, butadiene, and isoprene. Examples of the cyclic monomer constituting the cyclic polyolefin include cyclic alkenes such as norbornene; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these polyolefins, preferred are cyclic alkenes, and more preferred are norbornene. Styrene is also an example of a constituting monomer.

[0051] Examples of the carboxylic acid or anhydride thereof used for the acid modification include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride.

[0052] When either the first or second polyolefin layer 12a, 12b is formed from a polyolefin, examples of the polyolefin include the same polyolefins as those exemplified above as the acid-modified polyolefins or acid-modified cyclic polyolefins.

[0053] The first and second polyolefin layers 12a and 12b may each be formed of a single resin component or a blend polymer of two or more resin components.Furthermore, the first and second polyolefin layers 12a and 12b may each be formed of a single layer or two or more layers of the same or different resin components.

[0054] Furthermore, the first and second polyolefin layers 12a and 12b may each contain a filler, if necessary. When the first and second polyolefin layers 12a and 12b contain a filler, the filler functions as a spacer, effectively preventing short circuits between the metal terminal 2 and the barrier layer 33 of the packaging material 3. The particle size of the filler is approximately 0.1 to 35 μm, preferably approximately 5.0 to 30 μm, and more preferably approximately 10 to 25 μm. The content of the filler is approximately 5 to 30 parts by mass, preferably approximately 10 to 20 parts by mass, per 100 parts by mass of the resin components forming the first and second polyolefin layers 12a and 12b.

[0055] The filler may be either inorganic or organic. Examples of inorganic fillers include carbon (carbon, graphite), silica, aluminum oxide, barium titanate, iron oxide, silicon carbide, zirconium oxide, zirconium silicate, magnesium oxide, titanium oxide, calcium aluminate, calcium hydroxide, aluminum hydroxide, magnesium hydroxide, and calcium carbonate. Examples of organic fillers include fluororesins, phenolic resins, urea resins, epoxy resins, acrylic resins, benzoguanamine-formaldehyde condensates, melamine-formaldehyde condensates, cross-linked polymethyl methacrylates, and cross-linked polyethylenes. From the standpoints of shape stability, rigidity, and content resistance, aluminum oxide, silica, fluororesins, acrylic resins, and benzoguanamine-formaldehyde condensates are preferred, with spherical aluminum oxide and silica being particularly preferred. As a method for mixing the filler into the resin component that forms the polyolefin layer 12, a method in which the two are melt-blended in advance using a Banbury mixer or the like to form a masterbatch and then adjusted to a predetermined mixing ratio, or a method in which the filler is directly mixed with the resin component can be used.

[0056] The first and second polyolefin layers 12a and 12b may each contain a pigment, if necessary. Various inorganic pigments can be used as the pigment. A preferred example of the pigment is carbon (carbon, graphite), which is one of the fillers listed above. Carbon (carbon, graphite) is a material commonly used inside batteries and is unlikely to leach into the electrolyte. Furthermore, the pigment has a significant coloring effect, and a sufficient amount can be added without impairing adhesion. Furthermore, the pigment does not melt due to heat, and the apparent melt viscosity of the added resin can be increased. Furthermore, the pigment prevents the pressure-applied portion from becoming thin during thermal adhesion (heat sealing), thereby providing excellent sealing between the packaging material and the metal terminal.

[0057] When a pigment is added to the first and second polyolefin layers 12a, 12b, the amount of the pigment added is, for example, about 0.05 to 0.3 parts by mass, preferably about 0.1 to 0.2 parts by mass, per 100 parts by mass of the resin components forming the first and second polyolefin layers 12a, 12b when carbon black with a particle size of approximately 0.03 μm is used. Adding a pigment to the first and second polyolefin layers 12a, 12b makes it possible to detect the presence or absence of the adhesive film for metal terminal 1 using a sensor or to visually inspect the film. When a filler and a pigment are added to the first and second polyolefin layers 12a, 12b, the filler and pigment may be added to the same first and second polyolefin layers 12a, 12b. However, to avoid impairing the thermal adhesiveness of the adhesive film for metal terminal 1, it is preferable to add the filler and pigment separately to the first and second polyolefin layers 12a, 12b.

[0058] The first and second polyolefin layers 12a, 12b can each be composed of a resin film. When the first and second polyolefin layers 12a, 12b are composed of a resin film, the adhesive film for a metal terminal can be suitably produced by laminating a resin film formed from the above-mentioned polyolefin or acid-modified polyolefin onto the base film 11 using, for example, a dry lamination method. Alternatively, the adhesive film for a metal terminal can be suitably produced by extruding the resin constituting the first and second polyolefin layers 12a, 12b onto the base film 11.

[0059] When the first and second polyolefin layers 12a, 12b made of resin films are laminated on the surface of the base film 11, the surfaces of the first and second polyolefin layers 12a, 12b facing the base film 11 may be subjected to a known adhesion-facilitating treatment such as corona discharge treatment, ozone treatment, or plasma treatment, as necessary. In particular, corona discharge treatment enhances the adhesion between the base film 11 and the first polyolefin layer 12a and second polyolefin layer 12b, thereby providing excellent sealing between the packaging material and the metal terminal.

[0060] The thickness of the first and second polyolefin layers 12a, 12b can be appropriately selected depending on the layer structure of the adhesive film for metal terminal 1. Taking into consideration the filling of resin and pinholes after heat sealing, the lower limit of each is preferably about 5 μm or more, more preferably about 20 μm or more, and the upper limit is preferably about 80 μm or less, more preferably about 50 μm or less. The thickness ranges of the first and second polyolefin layers 12a, 12b are preferably about 5 to 80 μm, about 5 to 50 μm, about 20 to 80 μm, and about 20 to 50 μm, respectively.

[0061] [Adhesion promoter layer] The adhesion promoter layer (not shown) is a layer that is provided as needed for the purpose of firmly adhering the base film 11 to the first and second polyolefin layers 12a, 12b. The adhesion promoter layer may be provided on only one side between the base film 11 and the first and second polyolefin layers 12a, 12b, or on both sides.

[0062] The adhesion promoter layer can be formed using known adhesion promoters such as isocyanate-based, polyethyleneimine-based, polyester-based, polyurethane-based, and polybutadiene-based. From the viewpoint of further improving electrolyte resistance, it is preferable to form the adhesion promoter using an isocyanate-based adhesion promoter. As the isocyanate-based adhesion promoter, one containing an isocyanate component selected from triisocyanate monomer and polymeric MDI has excellent laminate strength and shows little decrease in laminate strength after immersion in an electrolyte. It is particularly preferable to form the adhesive layer using an adhesion promoter made from triphenylmethane-4,4',4"-triisocyanate, a triisocyanate monomer, or polymethylene polyphenyl polyisocyanate, a polymeric MDI (NCO content of approximately 30%, viscosity of 200 to 700 mPa·s). It is also preferable to form the adhesive layer using tris(p-isocyanatephenyl)thiophosphate, a triisocyanate monomer, or a two-component curing adhesion promoter that uses a polyethyleneimine-based compound as the main component and polycarbodiimide as the crosslinking agent.

[0063] The adhesion promoter layer can be formed by coating and drying using a known coating method such as bar coating, roll coating, or gravure coating. The amount of adhesion promoter to be applied is 20 to 100 mg / m in the case of an adhesion promoter made of triisocyanate. 2 Approximately, preferably 40 to 60 mg / m 2 In the case of adhesion promoters made of polymeric MDI, the concentration is 40 to 150 mg / m 2 Approximately, preferably 60 to 100 mg / m 2 In the case of a two-component curing adhesion promoter that uses polyethyleneimine as the main component and polycarbodiimide as the crosslinking agent, the adhesive strength is about 5 to 50 mg / m 2 about 10 to 30 mg / m 2 Triisocyanate monomer is a monomer with three isocyanate groups in one molecule, and polymeric MDI is a mixture of MDI and MDI oligomers formed by polymerizing MDI, and is represented by the following formula:

[0064] [ka]

[0065] The adhesive film 1 for metal terminals can be produced by laminating first and second polyolefin layers 12a, 12b, respectively, on both surfaces of a base film 11. The base film 11 and the first and second polyolefin layers 12a, 12b can be laminated by known methods such as extrusion lamination or thermal lamination. When laminating the base film 11 and the first and second polyolefin layers 12a, 12b via an adhesion promoter layer, for example, the adhesion promoter that constitutes the adhesion promoter layer can be applied and dried on the base film 11 by the above-mentioned method, and the first and second polyolefin layers 12a, 12b can be laminated on top of the adhesion promoter layer.

[0066] The thickness (total thickness) of the adhesive film 1 for metal terminals is not particularly limited, but the lower limit is preferably about 20 μm or more, more preferably about 50 μm or more, and the upper limit is preferably about 200 μm or less, more preferably about 150 μm or less. The thickness range is preferably about 20 to 200 μm, about 20 to 150 μm, about 50 to 200 μm, or about 50 to 150 μm.

[0067] The method for interposing the adhesive film 1 for metal terminals between the metal terminals 2 and the packaging material 3 is not particularly limited, and for example, as shown in Figures 1 to 3, the adhesive film 1 for metal terminals may be wrapped around the metal terminals 2 in the area where the metal terminals 2 are sandwiched between the packaging material 3. Furthermore, although not shown, the adhesive film 1 for metal terminals may be disposed on both sides of the metal terminals 2 so as to cross the two metal terminals 2 in the area where the metal terminals 2 are sandwiched between the packaging material 3.

[0068] The adhesive film 1 for a metal terminal of the present invention may also be in the form of a roll of adhesive film for a metal terminal, which is interposed between a metal terminal electrically connected to the positive and negative electrodes of a battery element including at least a positive electrode, a negative electrode, and an electrolyte, and a packaging material that seals the battery element. When in the form of a roll, the length of the adhesive film 1 for a metal terminal in the roll-up direction is, for example, about 50 to 500 m.

[0069] [Metal terminal 2] The metal terminal 2 (tab) is a conductive member electrically connected to an electrode (positive electrode or negative electrode) of the battery element 4, and is made of a metal material. The metal material constituting the metal terminal 2 is not particularly limited, and examples thereof include aluminum, nickel, and copper. For example, the metal terminal 2 connected to the positive electrode of a lithium ion battery is usually made of aluminum or the like. Furthermore, the metal terminal connected to the negative electrode of a lithium ion battery is usually made of copper, nickel, or the like.

[0070] To enhance electrolyte resistance, the surface of the metal terminal 2 is preferably subjected to a chemical conversion treatment. For example, when the metal terminal 2 is made of aluminum, specific examples of the chemical conversion treatment include known methods for forming an acid-resistant coating using phosphates, chromates, fluorides, triazine thiol compounds, etc. Among the methods for forming an acid-resistant coating, a preferred method is phosphate chromate treatment, which uses a compound consisting of three components: a phenolic resin, a chromium (III) fluoride compound, and phosphoric acid.

[0071] The size of the metal terminal 2 may be set appropriately depending on the size of the battery to be used, etc. The thickness of the metal terminal 2 is preferably about 50 to 1000 μm, more preferably about 70 to 800 μm. The length of the metal terminal 2 is preferably about 1 to 200 mm, more preferably about 3 to 150 mm. The width of the metal terminal 2 is preferably about 1 to 200 mm, more preferably about 3 to 150 mm.

[0072] [Packaging material 3] The packaging material 3 may have a laminate structure including at least a base material layer 31, a barrier layer 33, and a heat-sealable resin layer 35, in this order. FIG. 5 shows an example of the cross-sectional structure of the packaging material 3, in which the base material layer 31, an optional adhesive layer 32, a barrier layer 33, an optional adhesive layer 34, and a heat-sealable resin layer 35 are laminated in this order. In the packaging material 3, the base material layer 31 is the outermost layer, and the heat-sealable resin layer 35 is the innermost layer. During battery assembly, the battery element 4 is sealed by bringing the heat-sealable resin layers 35 located on the periphery of the battery element 4 into contact with each other and heat-sealing them, thereby sealing the battery element 4. While FIGS. 1 to 3 illustrate the battery 10 using an embossed packaging material 3 formed by embossing or the like, the packaging material 3 may also be an unformed pouch type. Pouch types include three-sided sealed, four-sided sealed, and pillow-shaped types, and any of these may be used.

[0073] (Base material layer 31) In the packaging material 3, the base layer 31 is a layer that functions as a base material for the packaging material and forms the outermost layer side.

[0074] The material for forming the base layer 31 is not particularly limited, as long as it has insulating properties. Examples of materials for forming the base layer 31 include polyester, polyamide, epoxy, acrylic, fluororesin, polyurethane, silicone resin, phenol, polyetherimide, polyimide, and mixtures or copolymers thereof. Polyesters such as polyethylene terephthalate and polybutylene terephthalate have the advantage of being highly resistant to electrolyte and being less susceptible to whitening due to adhesion of electrolyte, and are therefore preferably used as materials for forming the base layer 31. Furthermore, polyamide film has excellent stretchability and can prevent whitening due to resin cracking of the base layer 31 during molding, and is therefore preferably used as materials for forming the base layer 31.

[0075] The base layer 31 may be formed of a uniaxially or biaxially stretched resin film, or may be formed of an unstretched resin film. Among them, a uniaxially or biaxially stretched resin film, especially a biaxially stretched resin film, is preferably used as the base layer 31 because its heat resistance is improved by oriented crystallization.

[0076] Among these, the resin film forming the base layer 31 is preferably nylon or polyester, and more preferably biaxially oriented nylon or biaxially oriented polyester.

[0077] The base material layer 31 may be formed by laminating resin films made of different materials to improve pinhole resistance and insulation when used as a battery package. Specific examples include a multilayer structure in which a polyester film and a nylon film are laminated together, or a multilayer structure in which a biaxially oriented polyester film and a biaxially oriented nylon film are laminated together. When the base material layer 31 has a multilayer structure, the resin films may be bonded together via an adhesive, or may be directly laminated together without an adhesive. When bonding without an adhesive, examples of methods that bond the films in a hot-melt state include co-extrusion, sand lamination, and thermal lamination.

[0078] The base layer 31 may be made low-friction to improve formability. When making the base layer 31 low-friction, the coefficient of friction of the surface is not particularly limited, but may be, for example, 1.0 or less. To make the base layer 31 low-friction, for example, matte treatment, formation of a thin film layer of a slip agent, or a combination thereof may be used.

[0079] The thickness of the base layer 31 is, for example, about 10 to 50 μm, and preferably about 15 to 30 μm.

[0080] (Adhesive layer 32) In the packaging material 3, the adhesive layer 32 is a layer that is disposed on the base material layer 31 as needed to impart adhesion to the base material layer 31. That is, the adhesive layer 32 is provided between the base material layer 31 and the barrier layer 33.

[0081] The adhesive layer 32 is formed of an adhesive capable of bonding the base material layer 31 and the barrier layer 33. The adhesive used to form the adhesive layer 32 may be a two-component curing adhesive or a one-component curing adhesive. The bonding mechanism of the adhesive used to form the adhesive layer 32 is not particularly limited, and may be any of a chemical reaction type, a solvent volatilization type, a hot melt type, a hot pressure type, or the like.

[0082] The resin component of the adhesive that can be used to form the adhesive layer 32 is preferably a polyurethane-based two-component curing adhesive; polyamide, polyester, or a blend resin of these with modified polyolefin, from the viewpoint of having excellent ductility, durability and resistance to deformation under high humidity conditions, and resistance to thermal degradation during heat sealing, and effectively suppressing a decrease in the laminate strength between the base layer 31 and the barrier layer 33 and preventing delamination.

[0083] Furthermore, the adhesive layer 32 may be multi-layered with different adhesive components. When the adhesive layer 32 is multi-layered with different adhesive components, it is preferable to select a resin that has excellent adhesion to the base material layer 31 as the adhesive component disposed on the base material layer 31 side, and an adhesive component that has excellent adhesion to the barrier layer 33 as the adhesive component disposed on the barrier layer 33 side, from the viewpoint of improving the laminate strength between the base material layer 31 and the barrier layer 33. When the adhesive layer 32 is multi-layered with different adhesive components, specifically, preferred examples of the adhesive component disposed on the barrier layer 33 side include acid-modified polyolefin, metal-modified polyolefin, a mixed resin of polyester and acid-modified polyolefin, and a resin containing copolymer polyester.

[0084] The thickness of the adhesive layer 32 is, for example, about 2 to 50 μm, and preferably about 3 to 25 μm.

[0085] (Barrier layer 33) In the packaging material, the barrier layer 3 not only improves the strength of the packaging material but also functions to prevent water vapor, oxygen, light, and the like from penetrating into the battery. Specific examples of metals constituting the barrier layer 3 include aluminum, stainless steel, and titanium, with aluminum being preferred. The barrier layer 3 can be formed, for example, from a metal foil, a metal vapor-deposited film, an inorganic oxide vapor-deposited film, a carbon-containing inorganic oxide vapor-deposited film, or a film provided with these vapor-deposited films. It is preferably formed from a metal foil, and more preferably from an aluminum foil. From the viewpoint of preventing wrinkles and pinholes from forming in the barrier layer 3 during the production of the packaging material, it is more preferred that the barrier layer be formed from a soft aluminum foil such as annealed aluminum (JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, JIS H4000:2014 A8079P-O).

[0086] The thickness of the barrier layer 33 is preferably about 10 to 200 μm, more preferably about 20 to 100 μm, from the viewpoint of making the packaging material thinner and making it difficult for pinholes to occur during molding.

[0087] Furthermore, at least one surface, preferably both surfaces, of the barrier layer 3 are preferably subjected to a chemical conversion treatment in order to stabilize adhesion, prevent dissolution and corrosion, etc. Here, the chemical conversion treatment refers to a treatment for forming an acid-resistant film on the surface of the barrier layer.

[0088] [Adhesive layer 34] In the packaging material 3, the adhesive layer 34 is a layer that is provided as needed between the barrier layer 33 and the heat-sealable resin layer 35 in order to firmly bond the heat-sealable resin layer 35.

[0089] The adhesive layer 34 is formed of an adhesive capable of bonding the barrier layer 33 and the heat-sealable resin layer 35. The composition of the adhesive used to form the adhesive layer is not particularly limited, and examples thereof include a resin composition containing an acid-modified polyolefin. Examples of acid-modified polyolefins include the same as those exemplified for the first and second polyolefin layers 12a and 12b.

[0090] The thickness of the adhesive layer 34 is, for example, about 1 to 40 μm, and preferably about 2 to 30 μm.

[0091] [Thermal adhesive resin layer 35] In the packaging material 3, the heat-sealable resin layer 35 corresponds to the innermost layer, and is a layer that seals the battery element by heat-sealing the heat-sealable resin layers together when the battery is assembled.

[0092] The resin component used in the heat-fusible resin layer 35 is not particularly limited as long as it is heat-fusible, and examples thereof include polyolefins and cyclic polyolefins.

[0093] Specific examples of the polyolefin include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous polypropylenes such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); and ethylene-butene-propylene terpolymers. Among these polyolefins, polyethylene and polypropylene are preferred.

[0094] The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer, and examples of the olefin constituting the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, butadiene, and isoprene. Examples of the cyclic monomer constituting the cyclic polyolefin include cyclic alkenes such as norbornene; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these polyolefins, cyclic alkenes are preferred, and norbornene is more preferred. Styrene is also an example of a constituting monomer.

[0095] Among these resin components, preferred are crystalline or amorphous polyolefins, cyclic polyolefins, and blend polymers thereof; more preferred are polyethylene, polypropylene, copolymers of ethylene and norbornene, and blend polymers of two or more of these.

[0096] The heat-fusible resin layer 35 may be formed of one type of resin component alone, or may be formed of a blend polymer of two or more types of resin components. Furthermore, the heat-fusible resin layer 35 may be formed of only one layer, or may be formed of two or more layers of the same or different resin components.

[0097] The thickness of the heat-fusible resin layer 35 is not particularly limited, but may be about 2 to 2000 μm, preferably about 5 to 1000 μm, and more preferably about 10 to 500 μm. [Example]

[0098] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0099] <Maximum in-plane orientation direction of naphthalene rings (Y max Direction) Measurement The maximum in-plane orientation direction of the naphthalene rings contained in each base film (polyethylene naphthalate (PEN) film) used in the following Examples and Comparative Examples was Y max The direction was measured by the following method. First, infrared absorption spectra were obtained for the surface of the substrate film in 18 directions at intervals of 10° from 0° to 170° in the direction perpendicular to the thickness direction by polarization measurement using the single-reflection ATR method of Fourier transform infrared spectroscopy. Here, the surface of the substrate film is the surface on which the acid-modified polyolefin layer is laminated. Next, in each of these 18 directions, the 765 cm of the infrared absorption spectrum was measured. -1 Absorption peak intensity Y at 765 1181cm -1 Absorption peak intensity Y at 1181 The value Y was calculated by dividing by . Next, the maximum value Y among the obtained values ​​Y (18 values) was calculated. max The direction in which max The results are shown in Table 1. The specific conditions for measuring the infrared absorption spectrum are as follows:

[0100] (Infrared absorption spectrum measurement conditions) Spectrometer: Thermo IS10 Attachment: Single reflection ATR attachment (Seagull) Detector: MCT (Hg Cd Te) Resolution: 8cm -1 IRE:Ge Incident angle: 30° Polarizer: Wire grid, S polarization Baseline: 1800cm -1 From 2000cm -1 Average intensity at Absorption peak intensity Y 765 :760cm -1 From 770cm -1 Maximum peak intensity in the range value minus the baseline value Absorption peak intensity Y 1181 :1176cm -1 From 1186cm -1The maximum peak intensity in the range minus the baseline value

[0101] Examples 1-3 and Comparative Examples 1-2 <Preparation of adhesive film for metal terminals> The substrate film used was a sequentially biaxially stretched PEN film (thickness 12 μm) that had been subjected to corona discharge treatment on both sides. An adhesion promoter of triphenylmethane-4,4',4"-triisocyanate was applied to one side of the PEN film by gravure printing at a solid content of 50 mg / m. 2 After coating and drying, maleic acid-modified polypropylene (PPa) containing 0.15 parts by weight of carbon black was extruded and coated to a thickness of 30 μm using a T-die extruder. Next, the adhesion promoter and PPa were coated on the other side of the PEN film in the same manner. After that, an aging treatment was performed at 45°C for 72 hours to obtain an adhesive film for metal terminals (total thickness 72 μm) consisting of PPa layer / adhesion promoter layer / PEN film / adhesion promoter layer / PPa layer.

[0102] <Preparation of packaging materials> One side of the barrier layer, made of aluminum foil (thickness 40 μm), which had been chemically treated (phosphoric acid chromate treatment) on both sides with a chemical conversion treatment solution containing three components: phenolic resin, chromium fluoride (trivalent) compound, and phosphoric acid, was laminated to a substrate layer made of biaxially oriented nylon film (thickness 25 μm) by dry lamination. Specifically, a polyester adhesive was applied to one side of the barrier layer using gravure printing, and then dried (dry mass 4.0 g / m). 2 ), and a base material layer was attached, followed by aging treatment. Next, an adhesive layer (22.5 μm thick) made of maleic anhydride-modified polypropylene and a heat-sealable resin layer (22.5 μm thick) made of random polypropylene were co-extruded onto the other side of the barrier layer, and heated to obtain a battery packaging material consisting of the base material layer / adhesive layer / metal foil / adhesive layer / heat-sealable resin layer in this order.

[0103] <Preparation of test battery> The resulting packaging material was cut into a 160 mm (MD: Machine Direction, longitudinal direction) × 90 mm (TD: Transverse Direction, horizontal direction) strip. This was cold-formed (single-stage, drawn-in forming) to a forming depth of 3.0 mm at a pressure of 0.4 MPa using a rectangular forming die (female die, surface having a maximum height roughness (nominal Rz value) of 3.2 μm as specified in Table 2 of the surface roughness standard for comparison in JIS B 0659-1:2002, Annex 1 (Reference)) with a 50 mm (MD) × 30 mm (TD) opening and a corresponding forming die (male die, surface having a maximum height roughness (nominal Rz value) of 1.6 μm as specified in Table 2 of the surface roughness standard for comparison in JIS B 0659-1:2002, Annex 1 (Reference)). The heat-sealable resin layer was placed on the male mold side, with a 0.5 mm clearance between the male and female molds. The resulting forming cup position M is shown in Figure 6. Next, the molded packaging material was folded in half in the MD at the fold (midpoint P in the MD) so that the heat-sealable resin layers faced each other. A dummy cell (PET plate, 45 mm x 28 mm x 3 mm thick) was placed in the forming cup. Two adhesive films for metal terminals and two dummy metal terminals (0.1 mm thick, 5 mm wide, 30 mm long aluminum foil) were positioned as shown in Figure 7, and the two sides were heat-sealed along the forming cup, starting with the short side and then the long side. The two dummy metal terminals were positioned so that they would be removed from the short side. The heat-sealing conditions were 190°C, 3 seconds, and a pressure of 1.4 MPa using a 7 mm wide head. One side of the adhesive film for metal terminals was heat-sealed to a dummy metal terminal, and the other side was heat-sealed to a heat-sealable resin layer. After heat-sealing the two sides, the film was dried in a dry room for 24 hours. Then, 0.5 g of water was sealed in the dry room from the other side (not heat-sealed) as a virtual electrolyte, forming a case with an internal space (pressure 1 atm). Next, the periphery was cut so that the width of the heat-sealed portion between the heat-sealable resin layers was 3 mm, and test battery 13 was obtained.

[0104] <Packaging material opening test> As shown in Figure 8(a), the test battery 13 obtained above was placed in the space between two stainless steel plates, and the fixing spacer 20 was adjusted so that the distance W between the two stainless steel plates was 7.0 mm. Next, in this state, the battery was placed in a vacuum oven (AVO-310NS-D vacuum drying oven manufactured by AS ONE Corporation), the pressure inside the oven was set to 5000 Pa, and the temperature was raised to 120°C at a heating rate of 35°C / min (as shown in Figure 8(b)), and the test battery 13 expanded. The presence or absence of opening at the area where the adhesive film for metal terminals was located was confirmed. The results are shown in Table 1.

[0105] [Table 1]

[0106] In the batteries of Comparative Examples 1 and 2, when the portion where the packaging material had been opened was visually observed, it was confirmed that cohesive failure had occurred at the position of the base film of the adhesive film for metal terminal.

[0107] <Measurement of lamination strength between PEN film and PPa layer of adhesive film for metal terminals> The adhesive film for metal terminal obtained above was cut into a size of 100 mm (longitudinal direction) × 15 mm (lateral direction) to obtain a sample. At this time, for the samples of Examples 1 to 3 and Comparative Examples 1 and 2, the longitudinal direction of the sample and the Y direction of the adhesive film for metal terminal were max The adhesive film for metal terminals was cut to obtain samples so that the angles between the direction and the PEN film corresponded to the angle θ in Table 1. Next, at room temperature (25°C), the PEN film and PPa layer of the adhesive film for metal terminals were each chucked (chuck distance 50 mm) and pulled in the 180° direction (longitudinal direction) at a rate of 50 mm / min using a tensile tester (Shimadzu Corporation AGS-1kNX) to measure the laminate strength (N / 15m) between the PEN film and PPa layer of the adhesive film for metal terminals. The results are shown in Table 1. The laminate strength (N / 15m) is the average value of 20 samples. [Explanation of symbols]

[0108] 1. Adhesive film for metal terminals 2 metal terminals 3 Packaging materials 3a Peripheral edges of packaging material 4 Battery elements 5 Metal terminal with adhesive film for metal terminal 10 batteries 11 Base film 12a First polyolefin layer 12b Second polyolefin layer 13 Test battery 13a Edge 20 Fixing spacer 21 Stainless steel plate 31 Base material layer 32 Adhesive layer 33 Barrier Layer 34 Adhesive layer 35 Heat-fusible resin layer

Claims

1. A battery comprising: a battery element including at least a positive electrode, a negative electrode, and an electrolyte; a packaging material for sealing the battery element; and metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and extending outside the packaging material, an adhesive film for a metal terminal is disposed between the metal terminal and the packaging material; The adhesive film for a metal terminal includes a first polyolefin layer, a base film containing polyethylene naphthalate, and a second polyolefin layer in this order; At least one of the first polyolefin layer and the second polyolefin layer contains an acid-modified polyolefin, The acid-modified polyolefin is a polyolefin in which at least one of an ethylene-butene-propylene terpolymer and a polypropylene block copolymer is acid-modified, Y, measured by the following method: max and a direction in which the metal terminal extends outside the packaging material, the angle θ between the direction in which the metal terminal extends outside the packaging material is 45° or more and 135° or less. Y max The direction was measured by polarization measurement using a single-reflection ATR method of Fourier transform infrared spectroscopy. When infrared absorption spectra were obtained in 18 directions at intervals of 10° from 0° to 170° in a direction perpendicular to the thickness direction of the surface of the base film, the 765 cm -1 Absorption peak intensity Y 765 1181 cm -1 Absorption peak intensity Y 1181 The maximum value Y is calculated by dividing the Y by max The direction in which max The direction.

2. 2. The battery according to claim 1, wherein the thickness of the substrate film of the adhesive film for metal terminals is 10 μm or more and 50 μm or less.

3. The battery according to claim 1 or 2, wherein the first polyolefin layer and the second polyolefin layer of the adhesive film for a metal terminal contain an acid-modified polyolefin.

4. 4. The battery according to claim 1, wherein the thickness of the first polyolefin layer and the second polyolefin layer of the adhesive film for a metal terminal is 5 μm or more and 80 μm or less.

5. The battery according to any one of claims 1 to 4, wherein the adhesive film for metal terminals has a thickness of 20 µm or more and 200 µm or less.

6. 6. The battery according to claim 1, wherein the packaging material is composed of a laminate including at least a base layer, a barrier layer, and a heat-sealable resin layer in this order.

7. 7. The battery according to claim 1, wherein the first polyolefin layer and the second polyolefin layer each have a thickness of 20 μm or more and 80 μm or less.

8. 7. The battery according to claim 1, wherein the first polyolefin layer and the second polyolefin layer each have a thickness of 20 μm or more and 50 μm or less.

9. The battery according to any one of claims 1 to 8, wherein the thickness of the substrate film is 30 µm or more and 50 µm or less.

10. A method for manufacturing a battery including at least a battery element including a positive electrode, a negative electrode, and an electrolyte, a packaging material for sealing the battery element, and metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding outside the packaging material, and disposing an adhesive film for metal terminals between the metal terminals and the packaging material, The adhesive film for a metal terminal includes a first polyolefin layer, a base film containing polyethylene naphthalate, and a second polyolefin layer in this order, At least one of the first polyolefin layer and the second polyolefin layer contains an acid-modified polyolefin, The acid-modified polyolefin is a polyolefin in which at least one of an ethylene-butene-propylene terpolymer and a polypropylene block copolymer is acid-modified, Y, measured by the following method: max a direction in which the metal terminal extends outward from the packaging material such that an angle θ between the direction in which the metal terminal extends outward from the packaging material is 45° or more and 135° or less. Y max The direction was measured by polarization measurement using a single-reflection ATR method of Fourier transform infrared spectroscopy. When infrared absorption spectra were obtained in 18 directions at intervals of 10° from 0° to 170° in a direction perpendicular to the thickness direction of the surface of the base film, the 765 cm -1 Absorption peak intensity Y 765 1181 cm -1 Absorption peak intensity Y 1181 The maximum value Y is calculated by dividing the Y by max The direction in which max The direction.

11. A metal terminal with an adhesive film for a metal terminal, in which an adhesive film for a metal terminal is attached to a metal terminal of a battery, The adhesive film for a metal terminal includes a first polyolefin layer, a base film containing polyethylene naphthalate, and a second polyolefin layer in this order; At least one of the first polyolefin layer and the second polyolefin layer contains an acid-modified polyolefin, The acid-modified polyolefin is a polyolefin in which at least one of an ethylene-butene-propylene terpolymer and a polypropylene block copolymer is acid-modified, The direction in which the metal terminal extends outward from the battery when attached to the battery and the Y of the adhesive film for metal terminals measured by the following method. max The metal terminal with an adhesive film for a metal terminal, wherein the adhesive film for a metal terminal is attached to the metal terminal so that an angle θ formed with the direction is 45° or more and 135° or less. Y max The direction was measured by polarization measurement using a single-reflection ATR method of Fourier transform infrared spectroscopy. When infrared absorption spectra were obtained in 18 directions at intervals of 10° from 0° to 170° in a direction perpendicular to the thickness direction of the surface of the base film, the 765 cm -1 Absorption peak intensity Y 765 1181 cm -1 Absorption peak intensity Y 1181 The maximum value Y is calculated by dividing the Y by max The direction in which max The direction.

12. A roll of an adhesive film for metal terminals is interposed between metal terminals electrically connected to a positive electrode and a negative electrode of a battery element including at least a positive electrode, a negative electrode, and an electrolyte, and a packaging material that seals the battery element, The adhesive film for a metal terminal includes a first polyolefin layer, a base film containing polyethylene naphthalate, and a second polyolefin layer in this order; At least one of the first polyolefin layer and the second polyolefin layer contains an acid-modified polyolefin, The acid-modified polyolefin is a polyolefin in which at least one of an ethylene-butene-propylene terpolymer and a polypropylene block copolymer is acid-modified, Y, measured by the following method: max A roll of adhesive film for a metal terminal, wherein the angle θ formed by the winding direction and a direction perpendicular to the winding direction of the roll of adhesive film for a metal terminal is 45° or more and 135° or less. Y max The direction was measured by polarization measurement using a single-reflection ATR method of Fourier transform infrared spectroscopy. When infrared absorption spectra were obtained in 18 directions at intervals of 10° from 0° to 170° in a direction perpendicular to the thickness direction of the surface of the base film, the 765 cm -1 Absorption peak intensity Y 765 1181 cm -1 Absorption peak intensity Y 1181 The maximum value Y is calculated by dividing the Y by max The direction in which max The direction.

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