Lead wire for non-aqueous electrolyte battery, insulating film and non-aqueous electrolyte battery

Abstract

To provide a lead wire for a non-aqueous electrolyte battery excellent in adhesion of the non-aqueous electrolyte battery with a sealed container under high temperature.SOLUTION: A lead wire for a non-aqueous electrolyte battery of the present disclosure comprises: a conductor; and an insulating film that has a plurality of layers and covers at least a part of an outer peripheral surface of the conductor. The insulating film has a conductor coating layer laminated on a surface of the conductor, a first insulating layer laminated on the outermost surface of the insulating film, and a second insulating layer laminated on an inner surface of the first insulating layer. The conductor coating layer includes acid-modified polyolefin. The ratio of the shear breaking strength S1 of the first insulating layer at the same temperature as the second insulating layer to the shear breaking strength S2 of the second insulating layer at any one temperature between 80°C and 125°C (S1 / S2) is 0.33 or more and 3.0 or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a lead wire for a nonaqueous electrolyte battery, an insulating film, and a nonaqueous electrolyte battery. [Background technology]

[0002] As electronic devices become smaller and lighter, there is a demand for smaller and lighter electrical components, such as batteries and capacitors, used in these devices. For this reason, for example, nonaqueous electrolyte batteries have been adopted, in which a bag is used as a sealed container and a nonaqueous electrolyte (electrolytic solution), a positive electrode, and a negative electrode are sealed inside the bag. The nonaqueous electrolyte used is an electrolytic solution in which a fluorine-containing lithium salt, such as LiPF6 or LiBF4, is dissolved in propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, or the like.

[0003] The sealed container must be able to prevent the permeation of electrolyte and gas, and the intrusion of moisture from the outside. For this reason, a laminate film made by covering a metal layer such as aluminum foil with resin is used as the material for the sealed container, and the edges of two sheets of laminate film are heat-sealed to form the sealed container.

[0004] One end of the sealed container is an opening, and a nonaqueous electrolyte, positive and negative electrode plates, a separator, etc. are enclosed inside this opening. Furthermore, lead conductors, one end of which is connected to the positive and negative electrode plates, are arranged so as to extend from the inside to the outside of the sealed container. Finally, the opening is heat-sealed (thermally fused) to close the opening of the sealed container and also to bond the sealed container and the lead conductors together to seal the opening. This last heat-sealed part is called the seal part.

[0005] The lead conductor is covered with an insulating film at the portion corresponding to the seal, and the combination of the insulating film and the lead conductor is called a lead wire (tab lead) for a non-aqueous electrolyte battery. The sealed container and the lead conductor are bonded (thermally fused) via this insulating film. Therefore, this insulating film is required to have the property of maintaining adhesion between the lead conductor and the sealed container without causing a short circuit between the metal layer of the sealed container and the lead conductor.

[0006] As such a tab lead, for example, in the prior art, a lead wire for a non-aqueous electrolyte battery has been proposed in which a composite coating layer is formed by applying a treatment liquid containing a resin component including polyacrylic acid and polyacrylic acid amide and a metal salt to a lead conductor, and an insulator is provided on the outside of this composite coating layer (see Patent Document 1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-128096 Summary of the Invention

[0008] The lead wire for a nonaqueous electrolyte battery of the present disclosure comprises a conductor and an insulating film having a plurality of layers and covering at least a portion of the outer peripheral surface of the conductor, wherein the insulating film comprises a conductor coating layer laminated on the surface of the conductor, a first insulating layer laminated on the outermost surface of the insulating film, and a second insulating layer laminated on the inner surface of the first insulating layer, the conductor coating layer containing an acid-modified polyolefin, and a ratio (S1 / S2) of the shear fracture strength S1 of the first insulating layer at the same temperature as the second insulating layer to the shear fracture strength S2 of the second insulating layer at any one temperature of 80°C or higher and 125°C or lower of 0.33 or higher and 3.0 or lower. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of a lead wire for a nonaqueous electrolyte battery according to one embodiment of the present disclosure. [Figure 2]FIG. 2 is a partial cross-sectional view of a lead wire for a nonaqueous electrolyte battery according to one embodiment of the present disclosure. [Figure 3] FIG. 3 is a perspective view showing an example of a nonaqueous electrolyte battery including a lead wire for a nonaqueous electrolyte battery according to an embodiment of the present disclosure. [Figure 4] FIG. 4 is a longitudinal sectional view of the nonaqueous electrolyte battery of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Problem to be solved by this disclosure] In recent years, in response to demands for shorter charging times and longer driving ranges for electric vehicles, nonaqueous electrolyte batteries for vehicles are required to have rapid charge / discharge characteristics that enable them to charge and discharge large currents in a short time. As such rapid charge / discharge of nonaqueous electrolyte batteries increases, the environment in which they are used becomes hotter. Therefore, materials constituting nonaqueous electrolyte batteries are required to have higher heat resistance than before, and improving the adhesion between lead wires and the enclosure of the nonaqueous electrolyte battery at high temperatures has become a challenge.

[0011] An object of the present disclosure is to provide a lead wire for a nonaqueous electrolyte battery that has excellent adhesion to the enclosure of the nonaqueous electrolyte battery at high temperatures.

[0012] [Effects of this disclosure] According to the present disclosure, it is possible to provide a lead wire for a nonaqueous electrolyte battery that has excellent adhesion to the enclosure of the nonaqueous electrolyte battery at high temperatures.

[0013] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described.

[0014] The lead wire for a nonaqueous electrolyte battery of the present disclosure comprises a conductor and an insulating film having a plurality of layers and covering at least a portion of the outer peripheral surface of the conductor, wherein the insulating film comprises a conductor coating layer laminated on the surface of the conductor, a first insulating layer laminated on the outermost surface of the insulating film, and a second insulating layer laminated on the inner surface of the first insulating layer, the conductor coating layer containing an acid-modified polyolefin, and a ratio (S1 / S2) of the shear fracture strength S1 of the first insulating layer at the same temperature as the second insulating layer to the shear fracture strength S2 of the second insulating layer at any one temperature of 80°C or higher and 125°C or lower of 0.33 or higher and 3.0 or lower.

[0015] In the lead wire for a nonaqueous electrolyte battery, the insulating film has a conductor coating layer laminated on the surface of the conductor, and the conductor coating layer contains an acid-modified polyolefin, thereby providing good adhesion to the conductor. The insulating film also has a first insulating layer laminated on the outermost surface of the insulating film and a second insulating layer laminated on the inner surface of the first insulating layer, and the ratio (S1 / S2) of the shear fracture strength S1 of the first insulating layer at the same temperature as the second insulating layer to the shear fracture strength S2 of the second insulating layer at any one temperature in the range of 80°C to 125°C is 0.33 to 3.0, thereby providing a shear fracture strength in a temperature range reached by a high-power battery between the first insulating layer and the second insulating layer laminated on the inner surface of the first insulating layer that is close to each other. Typically, the upper limit of operating temperature for nonaqueous electrolyte batteries is around 60°C. When the electrolyte, etc., inside the battery deteriorates and turns into decomposition gas, causing internal pressure, delamination can occur. This can initially result in material breakdown of the insulating film, which acts as the delamination initiation point. The delamination then progresses from the initiation point, resulting in the entire adhesive bond being delaminated, resulting in leakage of the decomposition gas and electrolyte. However, in the case of the lead wire for a nonaqueous electrolyte battery, even if a force is applied to the insulating film in a direction that causes delamination at temperatures above this conventional upper limit, the shear fracture strength of the first insulating layer and the second insulating layer laminated on the inner surface of the first insulating layer is similar, so the fracture is not biased toward one layer. Even if a delamination initiation point occurs, further progression of the delamination can be suppressed. Therefore, when the lead wire for a nonaqueous electrolyte battery is housed in a sealed container for a nonaqueous electrolyte battery and the sealed container and the lead wire for a nonaqueous electrolyte battery are bonded via the insulating film, strong adhesion is likely to be maintained even at high temperatures. Therefore, the lead wire for a nonaqueous electrolyte battery exhibits excellent adhesion to the sealed container of a nonaqueous electrolyte battery at high temperatures.

[0016] The shear fracture strength is calculated by cutting the surface layer on each surface side of the sample to be measured with a cutting blade at a constant vertical speed of 0.5 μm / sec and a constant horizontal speed of 5 μm / sec, determining the horizontal force acting on the cutting blade during cutting and the cutting cross-sectional area, and using the determined horizontal force and cutting cross-sectional area, according to the following formula (1). τ=FH / 2AcotΦ (1) In equation (1), τ is the shear fracture strength (unit: MPa), FH is the horizontal force (unit: N (Newton)), and A is the cutting cross-sectional area (unit: mm 2 ) and Φ=45°. τ is a value calculated assuming a shear angle of Φ = 45°. The cutting blade used is made of single crystal diamond with a cutting width of 1 mm and a cutting angle of 60° (rake angle 20°, clearance angle 10°). The shear fracture strength is calculated as the arithmetic average of the values ​​measured at three randomly selected points on the surface to be measured. The shear fracture strength can be measured using a known measuring device. An example of such a measuring device is the SAICAS-NN model manufactured by Daipla Wintes. In the examples described below, the assumed shear strength was measured using the SAICAS-NN model manufactured by Daipla Wintes in constant speed mode (vertical speed 0.5 μm / sec and horizontal speed 5 μm / sec), cutting the entire thickness region from the surface of the sample to be measured with the cutting blade, and determining the horizontal force during cutting and the cutting cross-sectional area based on the region where the cutting force profile shows a stable slope, and the value was calculated using the above formula (1).

[0017] It is preferable that the shear fracture strength S2 is 3 MPa or more and 20 MPa or less, and the shear fracture strength S1 is 3 MPa or more and 20 MPa or less. By making the shear fracture strength S2 and the shear fracture strength S1 3 MPa or more and 20 MPa or less, the peel strength is improved, the strength of each layer constituting the insulating film is made uniform, and stress concentration can be suppressed, so that cracks and delamination of the insulating film, which forms a joint with the sealing container of the nonaqueous electrolyte battery, can be further suppressed.

[0018] It is preferable that the ratio (S1 / S2) of the shear fracture strength S1 of the first insulating layer at the same temperature as the second insulating layer to the shear fracture strength S2 of the second insulating layer at any one temperature of 80° C. to 125° C. be 0.67 or more and 1.50 or less. When the ratio (S1 / S2) of the shear fracture strength S1 to the shear fracture strength S2 is 0.67 or more and 1.50 or less, the lead wire for a nonaqueous electrolyte battery can further improve the adhesion to the enclosure of the nonaqueous electrolyte battery at high temperatures.

[0019] It is preferable that the shear fracture strength S2 is 6 MPa or more and 15 MPa or less, and the shear fracture strength S1 is 6 MPa or more and 15 MPa or less. When both the shear fracture strength S2 and the shear fracture strength S1 are 6 MPa or more and 15 MPa or less, the effect of suppressing cracking and delamination of the insulating film, which is the joint portion with the sealing container of the nonaqueous electrolyte battery, can be further improved.

[0020] Preferably, the second insulating layer has an average thickness T2 of 25 μm or more, and the first insulating layer has an average thickness T1 of 25 μm or more. By making the second insulating layer average thickness T2 and the first insulating layer average thickness T1 25 μm or more, the strength of the second insulating layer and the first insulating layer can be improved.

[0021] The insulating film is used in the lead wire for a nonaqueous electrolyte battery of the present disclosure. By using the insulating film, the lead wire for a nonaqueous electrolyte battery has excellent adhesion to the sealing container of the nonaqueous electrolyte battery at high temperatures.

[0022] The nonaqueous electrolyte battery of the present disclosure also includes an enclosed container and a plurality of lead wires for the nonaqueous electrolyte battery that are arranged to extend from the inside to the outside of the enclosed container, and the enclosed container is made of a sheet body in which an innermost resin layer, a metal layer, and an outermost resin layer are laminated in this order, and the innermost resin layer 27 and the first insulating layer are heat-sealed.

[0023] The nonaqueous electrolyte battery includes a plurality of lead wires for the nonaqueous electrolyte battery, and the first insulating layer of the lead wires is heat-sealed to the innermost resin layer of the sealed container, thereby providing excellent adhesion between the lead wires and the sealed container at high temperatures.

[0024] In the nonaqueous electrolyte battery, the ratio (S4 / S1) of the shear fracture strength S4 of the innermost resin layer at the same temperature as the first insulating layer to the shear fracture strength S1 of the first insulating layer at a temperature in the range of 80°C to 125°C is preferably 0.33 to 3.0. By setting the ratio of the shear fracture strengths of the heat-fused first insulating layer and the innermost resin layer at a temperature in the range of 80°C to 125°C to 0.33 to 3.0, the shear fracture strengths of the first insulating layer and the innermost resin layer of the sealed container to which the first insulating layer is heat-fused are close to each other at a temperature in the range of 80°C to 125°C. Therefore, even if a force is applied in a direction that causes the lead wire for a nonaqueous electrolyte battery to peel from the sealed container at high temperatures, stress concentration is unlikely to occur, cracking can be suppressed, and the adhesive strength between the first insulating layer and the innermost resin layer can be improved. Therefore, the nonaqueous electrolyte battery has excellent adhesion between the lead wire and the sealed container at high temperatures.

[0025] The shear fracture strength S4 is preferably 3 MPa or more and 20 MPa or less. If the shear fracture strength S4 of the innermost resin layer 27 at a temperature in the range of 80°C or more and 125°C or less is 3 MPa or more and 20 MPa or less, similar to the shear fracture strength S1 of the first insulating layer at a temperature in the range of 80°C or more and 125°C or less, the nonaqueous electrolyte battery is less likely to experience stress concentration even when a force is applied in a direction that causes the lead wire and the sealed container to peel off at high temperatures, and the effect of suppressing the occurrence of delamination and cracks in the first insulating layer and the innermost resin layer can be further improved.

[0026] [Details of the embodiments of the present disclosure] The lead wire for a nonaqueous electrolyte battery and the nonaqueous electrolyte battery according to the present disclosure will be described in detail below.

[0027] <Lead wire for non-aqueous electrolyte batteries> Fig. 1 is a perspective view of a lead wire for a nonaqueous electrolyte battery according to one embodiment of the present disclosure. Fig. 2 is a partial cross-sectional view of the lead wire for a nonaqueous electrolyte battery according to one embodiment of the present disclosure. As shown in Figs. 1 and 2, the lead wire 1 for a nonaqueous electrolyte battery includes a conductor 3 and a three-layer insulating film 5 that covers at least a portion of the outer circumferential surface of the conductor 3. The insulating film 5 includes a conductor coating layer 6 laminated on the surface of the conductor 3, a first insulating layer 8 laminated on the outermost surface of the insulating film 5, and a second insulating layer 7 laminated on the inner surface of the first insulating layer 8. The conductor corresponds to a lead conductor.

[0028] (conductor) The conductor 3 is connected to the electrodes of the nonaqueous electrolyte battery. The material of the conductor 3 is not particularly limited as long as it is a conductor that can be used to form a lead wire for a nonaqueous electrolyte battery. Examples of the material include metal materials such as aluminum, titanium, nickel, copper, aluminum alloys, titanium alloys, nickel alloys, and copper alloys, as well as materials obtained by plating these metal materials with nickel, gold, or the like. The material for the conductor 3 connected to the positive electrode of the nonaqueous electrolyte battery is preferably one that does not dissolve during discharge, and specifically, aluminum, titanium, aluminum alloys, and titanium alloys are preferred. On the other hand, the material for the conductor 3 connected to the negative electrode is preferably nickel, copper, nickel alloys, copper alloys, nickel-plated copper, or gold-plated copper. The conductor 3 may also be surface-treated to prevent corrosion by the electrolyte.

[0029] The lower limit of the average thickness of the conductor 3 is preferably 0.10 mm. When the average thickness of the conductor 3 is 0.10 mm or more, a sufficient amount of current can be passed through the battery for practical use. The lower limit of the average thickness of the conductor 3 may be 0.15 mm or even 0.20 mm. When the average thickness of the conductor 3 is 0.10 mm or less, resistance heat generation in the lead wire portion can be suppressed even when the lead wire is subjected to rapid charging and discharging. On the other hand, the upper limit of the average thickness of the conductor 3 is not particularly limited and can be appropriately set depending on, for example, the capacity of the nonaqueous electrolyte battery. For example, the upper limit of the average thickness is preferably 5 mm. The upper limit of the average thickness of the conductor 3 may even be 4 mm. The "average thickness" of the conductor 3 is the average value of thickness measurements at 10 points. Hereinafter, "average thickness" has the same meaning.

[0030] (insulating film) The insulating film 5 is used as an insulating film for a lead wire for a nonaqueous electrolyte battery. The insulating film 5 has multiple layers and is laminated on the outer peripheral surface of the conductor 3 so as to cover at least a portion of the outer peripheral surface of the conductor 3. The lower limit of the average thickness of the insulating film 5 is preferably 0.05 mm. If the average thickness of the insulating film 5 is less than 0.05 mm, it becomes difficult to fill the gap between the insulating film 5 and the sealed container 11 caused by a step equal to the thickness of the conductor 3 with the insulating film 5. The lower limit of the average thickness of the insulating film 5 may be 0.08 mm or even 0.10 mm. On the other hand, the upper limit of the average thickness of the insulating film 5 is preferably 0.30 mm. If the average thickness of the insulating film 5 exceeds 0.30 mm, the amount of moisture that permeates the insulating film 5 from the atmosphere and enters the nonaqueous electrolyte battery 10 increases, which may accelerate deterioration of the nonaqueous electrolyte battery 10. The upper limit of the average thickness of the insulating film 5 may be 0.25 mm or even 0.22 mm. In the present disclosure, the average thickness of the insulating film 5 is the average value of thickness measurements at 10 points on the surface of the outer circumferential surface of the insulating film 5 that has the largest area.

[0031] In this embodiment, the insulating film 5 has a conductor coating layer 6 laminated on the surface of the conductor 3, a first insulating layer 8 laminated on the outermost surface of the insulating film 5, and a second insulating layer 7 laminated on the inner surface of the first insulating layer 8.

[0032] (Conductor coating layer) The conductor coating layer 6 coats a part of the outer peripheral surface of the conductor 3. By having the conductor coating layer 6, the insulating film 5 can suppress corrosion of the conductor 3.

[0033] The conductor covering layer 6 contains an acid-modified polyolefin. When the conductor covering layer 6 contains an acid-modified polyolefin, the adhesiveness to the conductor is good, and the adhesiveness to the second insulating layer 7 can be sufficiently exhibited.

[0034] Examples of polyolefin resins to be acid-modified include polyethylene, polypropylene, etc. Among these, polypropylene is preferred.

[0035] The acid used for acid modification is not particularly limited as long as it does not impair the effects of the present invention, and examples thereof include unsaturated carboxylic acids and derivatives thereof. Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, itaconic acid, and fumaric acid. Examples of derivatives of unsaturated carboxylic acids include maleic acid monoesters, maleic anhydride, itaconic acid monoesters, itaconic anhydride, fumaric acid monoesters, and fumaric anhydride. Among these, derivatives of unsaturated carboxylic acids are preferred, and maleic anhydride is more preferred, from the viewpoint of further improving the adhesion (compatibility) between the olefin resin and the liquid crystal polymer.

[0036] The acid-modified polyolefin is preferably acid-modified polypropylene, and more preferably maleic anhydride polypropylene. When the acid-modified polyolefin is acid-modified polypropylene, and the second insulating layer 7 is made of polypropylene, the adhesion between the conductor coating layer 6 and the second insulating layer 7 is further improved.

[0037] The lower limit of the acid-modified polyolefin content in the conductive coating layer 6 is preferably 70% by mass. If the acid-modified polyolefin content is below this lower limit, it may be difficult to obtain practically sufficient material properties. Furthermore, the lower limit of the acid-modified polyolefin content in the conductive coating layer 6 may be 80% by mass, 90% by mass, or even 100% by mass.

[0038] The conductive coating layer 6 may contain a thermoplastic resin other than the acid-modified polyolefin and other known additives, such as antioxidants, flame retardants, tackifiers, lubricants, fillers, crystallization accelerators, and colorants, as long as the effects of the present disclosure are not impaired.

[0039] The lower limit of the average thickness T3 of the conductor coating layer 6 is preferably 20 μm. If the average thickness T3 of the conductor coating layer 6 is less than 20 μm, sufficient adhesion to the conductor may be insufficient. The lower limit of the average thickness T3 of the conductor coating layer 6 may be 30 μm or 40 μm. On the other hand, the upper limit of the average thickness T3 of the conductor coating layer 6 is preferably 150 μm. If the average thickness T3 of the conductor coating layer 6 exceeds 150 μm, the amount of moisture that permeates through the insulating film 5 from the atmosphere and enters the nonaqueous electrolyte battery 10 may increase, potentially accelerating battery degradation. The upper limit of the average thickness T3 of the conductor coating layer 6 may be 120 μm or 100 μm. Here, in the present disclosure, the average thickness T3 of the conductor coating layer 6 is the average value of thickness measurements at 10 points on the surface with the largest area among the outer peripheral surfaces of the conductor coating layer 6.

[0040] (Second insulating layer) The insulating film 5 has a second insulating layer 7 between the first insulating layer 8 and the conductor coating layer 6. The second insulating layer 7 is laminated on the inner surface of the first insulating layer 8. The second insulating layer 7 preferably contains a cross-linked polyolefin or a polyolefin having a melting point 10°C or more higher than that of the conductor coating layer 6. By containing a cross-linked polyolefin or a polyolefin resin having a melting point 10°C or more higher than that of the conductor coating layer 6, the second insulating layer 7 is less likely to melt at the heat-sealing temperature when the opening of the sealed container is heat-sealed, and short-circuiting between the metal layer of the sealed container and the conductor can be suppressed.

[0041] Examples of the polyolefin in the crosslinked polyolefin include polypropylene, polyethylene, and derivatives thereof. The crosslinked polyolefin is preferably a crosslinked random polypropylene having a melting point of 130°C or higher and 155°C or lower and an MFR of 3g / 10min or higher and 15g / 10min or lower. This ensures sufficient adhesion to the conductor coating layer 6 and the first insulating layer 8, and is less likely to melt at heat-sealing temperatures.

[0042] As the high-melting-point polyolefin, polypropylene having a melting point of 155° C. or higher is preferred, and homopolypropylene, block polypropylene, thermoplastic olefin elastomer (TPO), etc. are particularly preferred.

[0043] The lower limit of the cross-linked polyolefin content in the second insulating layer 7 is preferably 70% by mass. If the cross-linked polyolefin content is below this lower limit, it may be difficult to obtain sufficient material properties for practical use. The lower limit of the cross-linked polyolefin content in the second insulating layer 7 may also be 80% by mass, 90% by mass, or 100% by mass.

[0044] The second insulating layer 7 may contain a thermoplastic resin other than the crosslinked polyolefin and other known additives, such as antioxidants, flame retardants, tackifiers, lubricants, fillers, crystallization accelerators, and colorants, as long as the effects of the present disclosure are not impaired.

[0045] The lower limit of the average thickness T2 of the second insulating layer 7 is preferably 25 μm. If the average thickness T2 of the second insulating layer 7 is less than 25 μm, the strength of the second insulating layer 7 may be insufficient. The lower limit of the average thickness T2 of the second insulating layer 7 may be 30 μm or even 40 μm. On the other hand, the upper limit of the average thickness T2 of the second insulating layer 7 is preferably 250 μm. If the average thickness of the second insulating layer 7 exceeds 250 μm, the amount of moisture that permeates through the insulating film 5 from the atmosphere and enters the nonaqueous electrolyte battery increases, which may accelerate battery degradation. Here, in the present disclosure, the average thickness T2 of the second insulating layer 7 is the average of thickness measurements at 10 points on the surface with the largest area among the outer peripheral surfaces of the second insulating layer 7.

[0046] (First insulating layer) The first insulating layer 8 is disposed farthest from the conductor 3 and is made of a thermoplastic resin. The first insulating layer 8 is laminated on the outermost surface of the insulating film 5, and is laminated on the surface of the second insulating layer 7. The first insulating layer 8 preferably contains as its main component a resin that is easily melted at the heat-sealing temperature when the opening of the sealed container is heat-sealed (thermally fused), and more preferably contains as its main component a polyolefin. Here, in the present disclosure, the term "main component" refers to the component that has the largest content in terms of mass, for example, a component that is contained in the first insulating layer 8 at a content of 50 mass% or more.

[0047] Examples of polyolefins include polypropylene, polyethylene, and derivatives thereof. The polypropylene is preferably a random polypropylene having a melting point of 120°C or higher and 155°C or lower and an MFR of 3g / 10min or higher and 15g / 10min or lower. The random polypropylene used as the polyolefin has the advantage of being able to fully exhibit adhesion to the second insulating layer 7 and the innermost resin layer of the sealed container.

[0048] The lower limit of the polyolefin content in the first insulating layer 8 is preferably 70% by mass. If the polyolefin content is below this lower limit, it may be difficult to obtain sufficient material properties for practical use. The lower limit of the polyolefin content in the first insulating layer 8 may also be 80% by mass, 90% by mass, or 100% by mass.

[0049] The first insulating layer 8 may contain a thermoplastic resin other than the above polyolefin to the extent that the effects of the present disclosure are not impaired. More specifically, the first insulating layer 8 may contain a plurality of resins, and examples of these plurality of resins include combinations of homopolypropylene, block polypropylene, random polypropylene, low-crystalline polypropylene, low-density polyethylene, linear low-density polyethylene, low-crystalline ethylene-propylene copolymer, low-crystalline ethylene-butylene copolymer, low-crystalline ethylene-octene copolymer, low-crystalline propylene-ethylene copolymer, etc.

[0050] The first insulating layer 8 may contain other known additives to the extent that the effects of the present disclosure are not impaired. Examples of known additives include antioxidants, flame retardants, tackifiers, lubricants, fillers, crystallization accelerators, and colorants.

[0051] The lower limit of the average thickness T1 of the first insulating layer 8 is preferably 25 μm. If the average thickness T1 of the first insulating layer 8 is less than 25 μm, the strength of the first insulating layer 8 may be insufficient. The lower limit of the average thickness T1 of the first insulating layer 8 may be 30 μm or even 40 μm. On the other hand, the upper limit of the average thickness T1 of the first insulating layer 8 is preferably 250 μm. If the average thickness T1 of the first insulating layer 8 exceeds 250 μm, the amount of moisture that permeates through the insulating film 5 from the atmosphere and enters the nonaqueous electrolyte battery may increase, potentially accelerating battery degradation. Here, in the present disclosure, the average thickness T1 of the first insulating layer 8 is the average of thickness measurements at 10 points on the surface with the largest area among the outer peripheral surfaces of the first insulating layer 8.

[0052] The ratio (S1 / S2) of the shear fracture strength S1 of the first insulating layer 8 at the same temperature as the second insulating layer to the shear fracture strength S2 of the second insulating layer 7 at any one temperature in the range of 80° C. to 125° C. is 0.33 to 3.0, and preferably 0.67 to 1.5. When the ratio (S1 / S2) of the shear fracture strength S1 of the first insulating layer 8 at the same temperature as the second insulating layer to the shear fracture strength S2 of the second insulating layer 7 at any one temperature in the range of 80° C. to 125° C. is 0.33 to 3.0, the shear fracture strengths of the first insulating layer 8 and the second insulating layer 7 disposed between the conductive coating layer 6 and the first insulating layer 8 at any one temperature in the range of 80° C. to 125° C. are close to each other. Generally, the upper limit of usable temperature for nonaqueous electrolyte batteries is around 60°C. Even if a force is applied to the insulating film 5 in a direction that would cause peeling at temperatures exceeding this conventional upper limit, the shear fracture strengths of the first insulating layer and the second insulating layer laminated on the inner surface of the first insulating layer are similar. Therefore, even if a peeling-off point occurs, the peeling phenomenon is not biased toward one layer. Therefore, when the lead wire 1 for a nonaqueous electrolyte battery is housed in a sealed container of a nonaqueous electrolyte battery and the sealed container and the lead wire 1 for a nonaqueous electrolyte battery are bonded via the insulating film 5, strong adhesion is likely to be maintained even at high temperatures. Therefore, the lead wire 1 for a nonaqueous electrolyte battery has excellent adhesion to the sealed container of a nonaqueous electrolyte battery at high temperatures.

[0053] The lower limit of the shear fracture strength S2 of the second insulating layer 7 at any one temperature in the range of 80°C to 125°C may be 3 MPa or 6 MPa. The upper limit of the shear fracture strength S2 may be 20 MPa or 15 MPa. When the shear fracture strength S2 is 3 MPa or more and 20 MPa or less, peel strength is improved, the strength of each layer constituting the insulating film 5 is made uniform, and stress concentration can be suppressed, so that cracks and delamination of the insulating film 5, which is the joint portion with the sealing container of the nonaqueous electrolyte battery, can be further suppressed.

[0054] The lower limit of the shear fracture strength S1 of the first insulating layer 8 at any one temperature in the range of 80°C to 125°C may be 3 MPa or 6 MPa. The upper limit of the shear fracture strength S1 may be 20 MPa or 15 MPa. When the shear fracture strength S1 is 3 MPa or more and 20 MPa or less, peel strength is improved, the strength of each layer constituting the insulating film 5 is made uniform, and stress concentration can be suppressed, so that cracks and delamination of the insulating film 5, which is the joint portion with the sealing container of the nonaqueous electrolyte battery, can be further suppressed.

[0055] The shear fracture strength S2 of the second insulating layer 7 at any one temperature in the range of 80°C to 125°C and the shear fracture strength S1 of the first insulating layer 8 at the same temperature as the second insulating layer 7 can be adjusted, for example, by mixing two or more resins with different shear fracture strengths and inorganic fillers. Specifically, a resin with a low shear fracture strength of about 1 MPa to 3 MPa at 80°C, such as low-crystalline polypropylene, can be added in an appropriate mass ratio to a resin with a high shear fracture strength of about 25 MPa at 80°C, such as homopolypropylene. Furthermore, a desired high shear fracture strength can be achieved by adding an inorganic filler, such as a flame retardant or bulking agent, in an appropriate mass ratio.

[0056] [Method of manufacturing insulating film] The method for producing the insulating film of the present disclosure is not particularly limited. For example, a forming resin composition containing the respective resin components and additives of the conductor coating layer, second insulating layer, and first insulating layer is mixed using a known mixing device such as an open roll, pressure kneader, single-screw mixer, or twin-screw mixer. Next, when producing a single-layer film, the film-like conductor coating layer, second insulating layer, and first insulating layer can be produced by extrusion molding such as T-die molding or inflation molding. The conductor coating layer, second insulating layer, and first insulating layer are then superimposed and thermally laminated with a heated roll to form the insulating film. Alternatively, a co-extrusion inflation method or a T-die method can be used to simultaneously form multiple layers. Furthermore, an extrusion lamination method can be used in which a molten resin is laminated on a single-layer film.

[0057] By using the insulating film, the lead wire for a nonaqueous electrolyte battery has excellent adhesiveness to the sealing container of the nonaqueous electrolyte battery at high temperatures.

[0058] [Method of manufacturing lead wire for non-aqueous electrolyte battery] The method for producing the lead wire 1 for a nonaqueous electrolyte battery is not particularly limited, and the lead wire 1 for a nonaqueous electrolyte battery can be produced by a known method.

[0059] The lead wire for a nonaqueous electrolyte battery has excellent adhesiveness to the sealing container of the nonaqueous electrolyte battery at high temperatures.

[0060] <Non-aqueous electrolyte battery> The nonaqueous electrolyte battery 10 includes the above-described nonaqueous electrolyte battery lead wire 1. Examples of nonaqueous electrolyte batteries include secondary batteries such as lithium ion batteries.

[0061] FIG. 3 is a perspective view showing an example of a nonaqueous electrolyte battery including the lead wire for a nonaqueous electrolyte battery. FIG. 4 is a partial cross-sectional view schematically showing one embodiment of a nonaqueous electrolyte battery. The nonaqueous electrolyte battery (secondary battery) 10 shown in FIGS. 3 and 4 includes a plate-shaped positive electrode, a plate-shaped negative electrode, and a nonaqueous electrolyte (e.g., a nonaqueous electrolyte solution), all of which are not shown, an enclosed container 11, and multiple, specifically, two, lead wires 1 for a nonaqueous electrolyte battery. The lead wire 1 for a nonaqueous electrolyte battery is the lead wire for a nonaqueous electrolyte battery described above. As described above, the lead wire 1 for a nonaqueous electrolyte battery of this embodiment includes an insulating film 5 that includes a conductor coating layer 6, a second insulating layer 7, and a first insulating layer 8. The nonaqueous electrolyte battery 10 includes a substantially rectangular enclosed container 11 and two lead wires 1 for a nonaqueous electrolyte battery extending from the inside to the outside of the enclosed container 11. The conductor 3 and the enclosed container 11 are connected to a seal portion 13 of the enclosed container 11 via the insulating film 5. The sealed container 11 is a container that accommodates the positive electrode, the negative electrode, the separator, and the non-aqueous electrolyte in a sealed state.

[0062] Positive and negative electrodes (not shown) are stacked with separators interposed between them to form a stacked electrode group. This stacked electrode group and a non-aqueous electrolyte are housed in a sealed container 11. In this sealed container 11, the stacked electrode group is immersed in the electrolyte. The sealed container 11 is formed from a sheet body, as will be described later. In the sealed container 11, a seal portion 13 around two sheets or a folded sheet body is heat-sealed to form a sealed state.

[0063] Of the two lead wires 1 for a nonaqueous electrolyte battery, one lead wire 1 for a nonaqueous electrolyte battery is arranged so that one end 4a of the conductor 3 thereof is exposed from the sealed container 11 and the other end 4b is connected to the positive electrode inside the sealed container 11. The other lead wire 1 for a nonaqueous electrolyte battery is arranged so that one end 4a of the conductor 3 thereof is exposed from the sealed container 11 and the other end 4b is connected to the negative electrode inside the sealed container 11.

[0064] The innermost resin layer (i.e., the sealed container 11) is not laminated on either end portion of the conductor 3, i.e., the one end 4a and the other end 4b. The one end 4a of the conductor 3 is exposed from the sealed container 11. Meanwhile, an internal connection lead wire 14 is connected to the other end 4b of the conductor 3 of the positive-electrode lead wire 1 for a nonaqueous electrolyte battery via a solder portion 15, and the lead wire 14 is connected to a positive electrode (not shown). Similarly, an internal connection lead wire 14 is connected to the other end 4b of the conductor 3 of the negative-electrode lead wire 1 for a nonaqueous electrolyte battery via a solder portion 15, and the lead wire 14 is connected to a negative electrode (not shown). As shown in FIG. 4 , the middle portions of these nonaqueous electrolyte battery lead wires 1 are sandwiched between the sheet-like sealed container 11 and the insulating film 5, and the innermost resin layer 27 of the sealed container 11 and the first insulating layers 8 of the plurality of nonaqueous electrolyte battery lead wires 1 are heat-sealed in this portion.

[0065] The positive electrode and the negative electrode are typically laminates in which an active material layer containing an active material is laminated on the surface of a current collector such as a metal foil. The positive electrode and the negative electrode are usually in the form of a plate, but may have a shape other than a plate.

[0066] The separator is typically an insulating, porous film impregnated with a non-aqueous electrolyte.

[0067] The non-aqueous electrolyte contains a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent.

[0068] As shown in FIG. 4 , the sealed container 11 is composed of a sheet 18 in which an innermost resin layer 27, a metal layer 25, and an outermost resin layer 26 are laminated in this order. The sealed container 11 is produced by overlapping two sheets 18 and heat-sealing three sides other than the side through which the conductor passes. At the outer periphery of the sealed container, the metal layers 25 of each sheet are bonded via the innermost resin layer 27. At the seal portion 13, the conductor 3 of each lead wire 1 for a nonaqueous electrolyte battery is bonded to the sealed container 11 via the insulating film 5. At this portion, the innermost resin layer 27 of the sealed container 11 and the first insulating layer 8 of each lead wire 1 for a nonaqueous electrolyte battery are heat-sealed.

[0069] The innermost resin layer 27 is laminated directly on the inner surface of the metal layer 25. The innermost resin layer 27 located inside the sealed container 11 is preferably made of an insulating resin that does not dissolve in the non-aqueous electrolyte and melts when heated. For example, polyolefin, acid-modified polyolefin, acid-modified styrene-based elastomer, etc. can be used for the innermost resin layer 27. Among these, polypropylene is preferred for the innermost resin layer 27. The average thickness of the innermost resin layer 27 is preferably about 10 μm to 500 μm.

[0070] The metal layer 25 has functions such as improving the strength of the sealed container 11 and preventing the intrusion of water vapor, oxygen, light, etc. into the battery. The metal layer 25 is formed from a metal such as aluminum foil. The metal layer 25 is mainly composed of a metal. Examples of such metals include aluminum, copper, stainless steel, and titanium, with aluminum being particularly preferred. The metal layer 25 is essentially formed from a metal, but may also contain additives other than metals. The metal layer 25 is in the form of a film, and is preferably formed from a metal foil, and more preferably from an aluminum alloy foil. The average thickness of the metal layer 25 is preferably about 10 μm to 50 μm.

[0071] The outermost resin layer 26 has functions such as protecting the outer surface of the metal layer 25 and providing insulation. The outermost resin layer 26, which is located on the outside of the sealed container, is typically made of an insulating material, and is mainly composed of resin. Examples of resins that can be used to form the outermost resin layer 26 include polyethylene terephthalate (PET), polyamide, polyester, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, phenolic resin, polyetherimide, polyimide, and mixtures or copolymers thereof. The average thickness of the outermost resin layer 26 is preferably about 10 μm to 50 μm.

[0072] As described above, the nonaqueous electrolyte battery 10 is arranged such that one end of the lead wire 1 for a nonaqueous electrolyte battery, i.e., one end 4a of the conductor 3, is exposed from the sealed container 11 and is sealed by the sealed container 11. Specifically, the lead wire 1 for a nonaqueous electrolyte battery is arranged so that the innermost resin layer of the sealed container 11 and the insulating film 5 of the lead wire 1 for a nonaqueous electrolyte battery are in direct contact with each other. With the lead wire 1 for a nonaqueous electrolyte battery arranged in this manner, the innermost resin layer 27 in the seal portion 13 of the sealed container 11 and the first insulating layer 8 of the lead wire 1 for a nonaqueous electrolyte battery are heat-sealed. This allows the positive electrode, negative electrode, and separator, which are a stacked electrode group immersed in a nonaqueous electrolyte solution, to be sealed within the sealed container 11.

[0073] In the nonaqueous electrolyte battery 10, the ratio (S4 / S1) of the shear fracture strength S4 of the innermost resin layer 27 of the sealed container 11 at the same temperature as the first insulating layer 8 to the shear fracture strength S1 of the first insulating layer 8 at any one temperature in the range of 80°C to 125°C is 0.33 to 3.0, and preferably 0.67 to 1.50. By setting the ratio of the shear fracture strengths of the heat-fused innermost resin layer 27 and the first insulating layer at the same temperature in the range of 80°C to 125°C to be 0.33 to 3.0, the shear fracture strengths of the first insulating layer and the innermost resin layer of the sealed container to which the first insulating layer is heat-fused are close to each other at any one temperature in the range of 80°C to 125°C. Therefore, even if a force is generated in a direction that causes the lead wire for a nonaqueous electrolyte battery and the sealed container to separate at high temperatures, stress concentration is unlikely to occur, and it is possible to suppress the occurrence of delamination or cracks between the first insulating layer 8 and the innermost resin layer 27. Therefore, the nonaqueous electrolyte battery 10 has excellent adhesion between the lead wire 1 for a nonaqueous electrolyte battery and the sealed container 11 at high temperatures.

[0074] The lower limit of the shear fracture strength S4 of the innermost resin layer 27 at a temperature in the range of 80°C to 125°C may be 3 MPa or 6 MPa. The upper limit of the shear fracture strength S4 may be 20 MPa or 15 MPa. The shear fracture strength S4 of the innermost resin layer 27 at a temperature in the range of 80°C to 125°C is 3 MPa or more and 20 MPa or less, similar to the shear fracture strength S1 of the first insulating layer at the same temperature in the range of 80°C to 125°C. When the shear fracture strength S4 of the innermost resin layer 27 at a temperature in the range of 80°C to 125°C is 3 MPa or more and 20 MPa or less, the nonaqueous electrolyte battery 10 is less likely to experience stress concentration even when a force is applied in a direction that causes separation between the lead wire 1 for a nonaqueous electrolyte battery and the sealed container 11 at high temperatures, and the effect of suppressing delamination and cracking of the first insulating layer 8 and the innermost resin layer 27 can be further improved.

[0075] [Method of manufacturing non-aqueous electrolyte battery] A method for manufacturing a nonaqueous electrolyte battery according to an embodiment of the present disclosure can be appropriately selected from known methods, and includes, for example, the steps of preparing a lead wire for the nonaqueous electrolyte battery, preparing a stacked electrode group, preparing a nonaqueous electrolyte, and housing the stacked electrode group connected to the lead wire for the nonaqueous electrolyte battery and the nonaqueous electrolyte in a sealed container.

[0076] The nonaqueous electrolyte battery of this embodiment includes a plurality of lead wires for the nonaqueous electrolyte battery, and the first insulating layers of the lead wires are heat-sealed to the innermost resin layer of the sealed container, thereby providing excellent adhesion between the lead wires and the sealed container at high temperatures.

[0077] [Other embodiments] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is not limited to the configurations of the above-described embodiments, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0078] In the above embodiment, the lead wire for a nonaqueous electrolyte battery includes an insulating film having a three-layer structure including a conductive coating layer, a second insulating layer, and a first insulating layer. However, the lead wire for a nonaqueous electrolyte battery may include an insulating film having a multilayer structure including one or more intermediate layers inside the second insulating layer. [Example]

[0079] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0080] The materials used are shown below. [conductor] Aluminum plate (average thickness: 0.4 mm)

[0081] [Insulating film] 1. Conductive coating layer (PP0) Acid-modified random polypropylene: "Admer QE060" manufactured by Mitsui Chemicals (MFR 7g / 10min, melting point 140°C) 2. Second insulating layer (PP21) Block polypropylene: Novatec BC3AV manufactured by Japan Polypropylene Corporation (melting point 165°C, MFR 10g / 10min) (PP22) Block polypropylene: 80 parts by mass of "Novatec BC3AV" (MFR 10g / 10 min, melting point 165°C) manufactured by Japan Polypropylene Corporation, and 20 parts by mass of "Tafmer P0280" (Melting point 50°C or less, MFR 6g / 10 min) manufactured by Mitsui Chemicals, Inc. (PP23) Block polypropylene: 85 parts by mass of "Novatec BC3AV" manufactured by Japan Polypropylene Corporation and 15 parts by mass of ethylene propylene copolymer: "Tafmer P0280" manufactured by Mitsui Chemicals, Inc. (melting point 50°C or less, MFR 6g / 10 min) kneaded together (PP24) Block polypropylene: 60 parts by mass of "Novatec BC3AV" manufactured by Japan Polypropylene Corporation and 40 parts by mass of ethylene propylene copolymer: "Tafmer P0280" manufactured by Mitsui Chemicals, Inc. (melting point 50°C or less, MFR 6g / 10 min) kneaded together (PP25) Block polypropylene: 90 parts by mass of "Novatec BC3AV" manufactured by Japan Polypropylene Corporation and 10 parts by mass of ethylene propylene copolymer: "Tafmer P0280" manufactured by Mitsui Chemicals, Inc. (melting point 50°C or less, MFR 6g / 10 min) kneaded together (PP26) Homopolypropylene: "Homo MA3H" manufactured by Japan Polypropylene Corporation (MFR 10g / 10min, melting point 165°C) (PP27) Homopolypropylene: 100 parts by mass of "Homo MA3H" manufactured by Japan Polypropylene Corporation and Shimgon talc (average particle size 8 μm, specific surface area 13 m) manufactured by Nippon Talc Co., Ltd. 2 / g) 5 parts by mass (PP28) Block polypropylene: 40 parts by mass of "Novatec BC3AV" manufactured by Japan Polypropylene Corporation and 60 parts by mass of ethylene propylene copolymer: "Tafmer P0280" manufactured by Mitsui Chemicals, Inc. (melting point 50°C or less, MFR 6g / 10 min) kneaded together 3. First insulating layer (PP11) Random polypropylene: 70 parts by mass of Prime Polypro F227D manufactured by Prime Polypro Co., Ltd. and 30 parts by mass of ethylene propylene copolymer: Toughmer P0280 manufactured by Mitsui Chemicals, Inc. (melting point 50°C or less, MFR 6g / 10 min) kneaded together (PP12) Random polypropylene: 80 parts by mass of Prime Polypro F227D manufactured by Prime Polypro Co., Ltd. and 20 parts by mass of ethylene propylene copolymer: Toughmer P0280 manufactured by Mitsui Chemicals, Inc. (melting point 50°C or less, MFR 6g / 10 min) kneaded together (PP13) Random polypropylene: 60 parts by mass of Prime Polypro F227D manufactured by Prime Polypro Co., Ltd. and 40 parts by mass of ethylene propylene copolymer: Toughmer P0280 manufactured by Mitsui Chemicals, Inc. (melting point 50°C or less, MFR 6g / 10 min) kneaded together (PP14) Random polypropylene: 90 parts by mass of Prime Polypro F227D manufactured by Prime Polypro Co., Ltd. and 10 parts by mass of ethylene propylene copolymer: Toughmer P0280 manufactured by Mitsui Chemicals, Inc. (melting point 50°C or less, MFR 6g / 10 min) kneaded together (PP15) Random polypropylene: Prime Polypro F227D (MFR 7g / 10min, melting point 140°C) manufactured by Prime Polypro Co., Ltd. (PP16) Random polypropylene: SunAllomer PF621S (MFR 6g / 10min, melting point 150°C) manufactured by SunAllomer Co., Ltd. (PP17) Random polypropylene: 100 parts by mass of "Sunallomer PF621S" manufactured by Sunallomer Co., Ltd. and Shimgon talc (average particle size 8 μm, specific surface area 13 m) manufactured by Nippon Talc Co., Ltd. 2 / g) 5 parts by mass (PP18) Flexible polypropylene resin: "Welnex RFX4V" manufactured by Japan Polypropylene Corporation (melting point 140°C, MFR 6g / 10min)

[0082] [Sealed container] The aluminum packaging material "EL408PH(3)" manufactured by DNP and having the following composition was used. 1. Innermost resin layer PP4 Acid-modified random polypropylene, Admer QE060 (MFR 7g / 10min, melting point 140℃) manufactured by Mitsui Chemicals 2. Metal layer Aluminum layer (average thickness: 40 μm) 3.Outermost resin layer Aliphatic polyamide (Nylon 6,6: registered trademark)

[0083] [Test No. 1] (Insulating film preparation) The resin compositions for the conductor coating layer, second insulating layer, and first insulating layer were prepared using the resins listed in Tables 1 to 3. The resin compositions for the conductor coating layer, second insulating layer, and first insulating layer, each having the composition listed in Tables 1 to 3, were prepared using a mixer. Using a coat hanger-type, three-kind, three-layer T-die film-forming machine equipped with three single-screw extruders, the conductor coating layer resin composition was loaded into the first extruder, the second insulating layer resin composition into the second extruder, and the first insulating layer resin composition into the third extruder. The resulting mixture was co-extruded to obtain a three-layer insulating film laminated in the order conductor coating layer resin composition / second insulating layer resin composition / first insulating layer resin composition. The average thicknesses of the conductor coating layer, second insulating layer, and first insulating layer were 50 μm, 50 μm, and 50 μm, respectively.

[0084] (Fabrication of lead wire for non-aqueous electrolyte battery) Next, the obtained three-layer insulating film was cut to a predetermined size and heat-sealed to both sides of the conductor under conditions of a mold temperature of 220°C and a surface pressure of 0.3 MPa, thereby obtaining No. 1 lead wire for a nonaqueous electrolyte battery.

[0085] (Preparation of sealed container) Two 15 μm thick aliphatic polyamide sheets were dry-laminated onto one side of a 40 μm thick aluminum foil, and an 80 μm thick PP4 resin sheet was thermally laminated onto the other side to obtain a laminate film. The resulting laminate film was used with the aliphatic polyamide resin sheet as the outermost resin layer to produce an enclosed container with one side sealed to form an opening.

[0086] (Fabrication of non-aqueous electrolyte battery) Using the lead wire and the sealed container obtained as described above, the seal portion through which the lead wire passed was heat-sealed under conditions of 200° C., a surface pressure of 2.0 MPa, and 3 seconds to prepare a nonaqueous electrolyte battery.

[0087] [No.2~No.29] A nonaqueous electrolyte battery was obtained in the same manner as No. 1, except that the resin compositions of the conductive coating layer, the second insulating layer, and the first insulating layer, and the average thicknesses of the insulating layers were as shown in Tables 1 to 3.

[0088] [evaluation] (Measurement of shear fracture strength) The shear fracture strength of the second insulating layer, the first insulating layer, and the innermost resin layer of the sealing container of the obtained lead wires for nonaqueous electrolyte batteries Nos. 2 to 4, 6 to 23, 25, and 27 to 29 was measured in the temperature range of 80° C. to 125° C. by the method described above. The results are shown in Tables 1 to 3. For Nos. 1, 5, 24 and 26, the shear fracture strength at 60°C was measured as a reference example by the above-mentioned method.

[0089] (peel strength) The peel strength between the insulating film and the laminate film serving as the sealing container was measured by the following procedure. A MinebeaMitsumi "TGI-2kN" tensile tester with a 1kN load cell and the optional "THB-B" thermostatic chamber was used. After the sample was placed in the thermostatic chamber, the test was performed three minutes after the chamber stabilized at the desired temperature. The distance between the chucks was set to 20mm. A metal flat chuck with file marks was used, with the lower chuck gripping the conductive plate and the upper chuck gripping the aluminum packaging. The upper chuck was operated to achieve a 180° peel, and the peel strength [N / cm] was measured at a peel speed of 50mm / min. The peel strength values ​​[N / cm] for the 180° peel test listed in Tables 1 to 3 are calculated by dividing the maximum test force obtained by the test by the width of the test specimen. The 180° peel test was performed at a peel rate of 50 mm / min at a measurement temperature range of 80° C. to 125° C. shown in Tables 1 to 3, and the peel strength was recorded. The results are shown in Tables 1 to 3.

[0090] (Overall judgment of peel test results) An overall evaluation was made based on the peel strength results measured at temperatures between 80°C and 125°C. The overall evaluation was rated on a three-point scale: A, B, and C. The evaluation criteria for the overall evaluation were as follows: A or B was considered a pass. A: 60 or above. B: 40 or more and less than 60. C: Less than 40.

[0091] [Table 1]

[0092] [Table 2]

[0093] [Table 3]

[0094] As shown in Tables 1 to 3, Nos. 2 to 4 and Nos. 6 to 23, in which the conductor coating layer of the insulating film contains an acid-modified polyolefin and the ratio (S1 / S2) of the shear fracture strength S1 of the first insulating layer at the same temperature as the second insulating layer to the shear fracture strength S2 of the second insulating layer at any one temperature between 80° C. and 125° C. is between 0.33 and 3.0, exhibited good peel strength at temperatures between 80° C. and 125° C. In particular, Nos. 6 to 9, Nos. 11 to 17, and Nos. 19 to 23, in which the ratio (S1 / S2) of the shear fracture strength S1 of the second insulating layer at any one temperature between 80° C. and 125° C. is between 0.67 and 1.50, exhibited particularly excellent peel strength at temperatures between 80° C. and 125° C. On the other hand, the lead wires for nonaqueous electrolyte batteries No. 25 and No. 27 to No. 29, which had a ratio (S1 / S2) of shear fracture strength S1 of less than 0.33 or more than 3.0, exhibited low peel strength values ​​at temperatures ranging from 80° C. to 125° C. Furthermore, although No. 26 exhibited good peel strength at 60° C., Nos. 27 and 28, which had an insulating film and a sealed container of the same composition, exhibited reduced shear fracture strength S1 ratio (S1 / S2) and reduced peel strength when evaluated at 80° C. or 120° C.

[0095] The above results demonstrate that the lead wire for a nonaqueous electrolyte battery has excellent adhesion to the enclosure of the nonaqueous electrolyte battery at high temperatures. [Explanation of symbols]

[0096] 1. Lead wire for non-aqueous electrolyte battery 3 Conductors 4a One end 4b Other end 5. Insulating film 6 Conductor coating layer 7 Second insulating layer 8 First insulating layer 10. Non-aqueous electrolyte battery 11 Enclosure 13 Seal part 14 Internal connection lead wire 15 Soldering part 25 metal layer 26 Outermost resin layer 27 Innermost resin layer

Claims

1. A conductor; an insulating film having a plurality of layers and covering at least a part of the outer circumferential surface of the conductor; Equipped with the insulating film has a conductor covering layer laminated on the surface of the conductor, a first insulating layer laminated on the outermost surface of the insulating film, and a second insulating layer laminated on the inner surface of the first insulating layer, the conductor coating layer contains an acid-modified polyolefin, The lead wire for a nonaqueous electrolyte battery, wherein the second insulating layer has a shear fracture strength S2 of 6 MPa or more and 17 MPa or less at a temperature of 80°C or more and 125°C or less, and the first insulating layer has a shear fracture strength S1 of 6 MPa or more and 16 MPa or less at a temperature of 80°C or more and 125°C or less.

2. 2. The lead wire for a non-aqueous electrolyte battery according to claim 1, wherein the shear fracture strength S2 is 15 MPa or less.

3. The average thickness T2 of the second insulating layer is 25 μm or more, 3. The lead wire for a non-aqueous electrolyte battery according to claim 1, wherein the first insulating layer has an average thickness T1 of 25 [mu]m or more.

4. An insulating film used in the lead wire for a nonaqueous electrolyte battery according to any one of claims 1 to 3.

5. An enclosure; a plurality of lead wires for a nonaqueous electrolyte battery according to any one of claims 1 to 3, which are arranged so as to extend from the inside to the outside of the sealing container; Equipped with the sealed container is composed of a sheet body in which an innermost resin layer, a metal layer, and an outermost resin layer are laminated in this order, The nonaqueous electrolyte battery has the innermost resin layer and the first insulating layer heat-sealed together.

6. 6. The nonaqueous electrolyte battery according to claim 5, wherein a ratio (S4 / S1) of a shear fracture strength S4 of the innermost resin layer at the same temperature as that of the first insulating layer to a shear fracture strength S1 of the first insulating layer at any one temperature in a range of 80°C or higher and 125°C or lower is 0.50 or higher and 1.60 or lower.

7. 7. The nonaqueous electrolyte battery according to claim 6, wherein the shear fracture strength S4 is 3 MPa or more and 20 MPa or less.

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