Lead wire for non-aqueous electrolyte batteries and non-aqueous electrolyte batteries

Abstract

This lead wire for a non-aqueous electrolyte battery comprises a conductor and an insulating film that has at least one layer and covers at least a portion of an outer circumferential surface of the conductor. The conductor has a conductor coating film that covers at least a portion of the surface thereof. The conductor coating film contains a metal element and a trivalent chromium compound that includes chromium hydroxide. The ratio of the number of atoms of chromium included in the chromium hydroxide to the number of atoms of chromium included in the trivalent chromium compound at the topmost surface of the conductor coating film is 0.40–0.85. The insulating film has an innermost layer that is layered on the surface of the conductor coating film. The innermost layer includes, as a principal component, a resin component that includes a maleic anhydride–modified polypropylene. The acid modification rate of the resin component is 0.02–0.50 mass%.

Description

[Technical Field]

[0001] This disclosure relates to lead wires for non-aqueous electrolyte batteries and non-aqueous electrolyte batteries. [Background technology]

[0002] With the miniaturization and weight reduction of electronic devices, there is a demand for smaller and lighter electrical components such as batteries and capacitors used in these devices. For this reason, non-aqueous electrolyte batteries are being adopted, for example, in which a bag is used as a sealed container and a non-aqueous electrolyte, positive electrode, and negative electrode are sealed inside. As the non-aqueous electrolyte, an electrolyte is used in which lithium salts containing fluorine, such as LiPF6 and LiBF4, are dissolved in propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, or ethylmethyl carbonate.

[0003] Encapsulated containers are required to have properties that prevent the permeation of electrolytes and gases, as well as the ingress of moisture from the outside. For this reason, laminated film, which consists of a metal layer such as aluminum foil coated with resin, is used as the material for enclosed containers, and the edges of two laminated films are heat-fused together to form the enclosed container.

[0004] One end of the sealed container is an opening, and a non-aqueous electrolyte, a positive electrode plate, a negative electrode plate, a separator, etc., are sealed inside. Furthermore, lead conductors, one end of which is connected to the positive electrode plate and the negative electrode plate, are arranged to extend from the inside to the outside of the sealed container. Finally, the opening of the sealed container is closed by heat sealing (thermal fusion), and the sealed container and the lead conductors are bonded together to seal the opening. This final heat-fused portion is called the seal portion.

[0005] The portion of the lead conductor corresponding to the sealing area is covered with an insulating film, and a lead wire with both the insulating film and the lead conductor is called a lead wire for non-aqueous electrolyte batteries (tab lead). The sealed container and the lead conductor are bonded (heat-fused) via this insulating film. Therefore, this insulating film is required to have the characteristic 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 for the tab leads mentioned above, a conventional technology has proposed a non-aqueous electrolyte battery in which different metals are used for the conductors of the positive electrode connection lead wire and the negative electrode connection lead wire, and the lead wires are provided with an insulating layer that does not melt at the heat-sealing temperature of the sealed bag (see Patent Document 1). [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 9-265974 [Overview of the Initiative]

[0008] The lead wire for a non-aqueous electrolyte battery of the present disclosure comprises a conductor and an insulating film having one or more layers and covering at least a portion of the outer surface of the conductor, wherein the conductor has a conductor coating covering at least a portion of its surface, the conductor coating contains a trivalent chromium compound including chromium hydroxide and a metal element, the ratio of the number of chromium atoms in the chromium hydroxide to the number of chromium atoms in the trivalent chromium compound at the outermost surface of the conductor coating is 0.40 or more and 0.85 or less, the insulating film has an innermost layer laminated on the surface of the conductor coating, the innermost layer mainly consists of a resin component including maleic anhydride-modified polypropylene, and the acid modification rate of the resin component is 0.02% by mass or more and 0.50% by mass or less. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a perspective view of a lead wire for a non-aqueous electrolyte battery according to one embodiment of the present disclosure. [Figure 2] Figure 2 is a partial cross-sectional view of a lead wire for a non-aqueous electrolyte battery according to one embodiment of the present disclosure. [Figure 3] Figure 3 is a perspective view showing an example of a non-aqueous electrolyte battery equipped with lead wires for a non-aqueous electrolyte battery according to one embodiment of the present disclosure. [Figure 4] Figure 4 is a longitudinal cross-sectional view in the thickness direction of the non-aqueous electrolyte battery shown in Figure 3. [Modes for carrying out the invention]

[0010] [Issues this disclosure aims to address] Even if such tab leads have sufficient adhesion immediately after sealing the opening of the enclosed container, prolonged use can lead to moisture permeation through the seal. This permeated moisture reacts with the non-aqueous electrolyte sealed inside the container, generating hydrofluoric acid. Hydrofluoric acid is highly corrosive to metal lead conductors, and this corrosion can cause delamination at the interface between the conductor and the insulating film. Therefore, improved resistance to non-aqueous electrolytes is required for tab leads.

[0011] The purpose of this disclosure is to provide a lead wire for a non-aqueous electrolyte battery that has excellent resistance to the non-aqueous electrolyte of the non-aqueous electrolyte battery.

[0012] [Effects of this disclosure] According to this disclosure, it is possible to provide lead wires for non-aqueous electrolyte batteries that have excellent resistance to the non-aqueous electrolyte of the non-aqueous electrolyte battery.

[0013] [Description of Embodiments in this Disclosure] First, embodiments of this disclosure will be listed and described.

[0014] The lead wires for non-aqueous electrolyte batteries disclosed herein are (1) A conductor and an insulating film having one or more layers that covers at least a portion of the outer surface of the conductor, wherein the conductor has a conductive film that covers at least a portion of its surface, the conductive film contains a trivalent chromium compound including chromium hydroxide and a metal element, the ratio of the number of chromium atoms in the chromium hydroxide to the number of chromium atoms in the trivalent chromium compound at the outermost surface of the conductive film is 0.40 or more and 0.85 or less, the insulating film has an innermost layer laminated on the surface of the conductive film, the innermost layer mainly consists of a resin component including maleic anhydride-modified polypropylene, and the acid modification rate of the resin component is 0.02% by mass or more and 0.50% by mass or less.

[0015] In the lead wire for the non-aqueous electrolyte battery, the conductor is coated with a conductive film containing a trivalent chromium compound including chromium hydroxide and a metal element, thereby suppressing peeling at the interface between the conductor and the insulating film caused by corrosion of the conductor by hydrofluoric acid generated by the hydrolysis of the non-aqueous electrolyte. Furthermore, the innermost layer laminated on the surface of the conductive film is mainly composed of a resin component containing maleic anhydride-modified polypropylene, and the acid modification rate of the resin component is 0.02% by mass or more and 0.50% by mass or less, resulting in good adhesion between the innermost layer and the conductive film. Furthermore, by having a ratio of the number of chromium atoms in the chromium hydroxide to the number of chromium atoms in the trivalent chromium compound at the outermost surface of the conductive coating of 0.40 to 0.85, the conductive coating has a sufficient amount of hydrogen bonding with the maleic anhydride-modified polypropylene in the innermost layer, and the mechanical strength of the conductive coating is good, thereby improving the adhesive strength between the conductor and the insulating film. On the other hand, the outermost surface of the conductive coating has a ratio of the number of chromium atoms in the chromium hydroxide to the number of chromium atoms in the trivalent chromium compound at the outermost surface of the conductive coating of 0.40 to 0.85, so the amount of hydroxyl groups on the surface is less than that of an untreated conductor surface, which is thought to be covered with almost 100% hydroxide due to the adhesion of moisture from the atmosphere. In contrast, by setting the acid modification rate of the resin component, which is the main component of the innermost layer, to 0.02% by mass or more and 0.50% by mass or less, the frequency of hydrogen bond formation between the hydroxyl groups on the conductor surface and the maleic anhydride-modified groups of the resin component can be kept within a good range, thereby further improving the adhesive strength between the conductor and the insulating film. Therefore, the lead wires for non-aqueous electrolyte batteries have excellent resistance to the non-aqueous electrolyte of the non-aqueous electrolyte battery.

[0016] The ratio of the number of chromium atoms in the chromium hydroxide to the number of chromium atoms in the trivalent chromium compound at the outermost surface of the conductive film is calculated using X-ray photoelectron spectroscopy (hereinafter also referred to as "XPS"). The term "on the outermost surface of the conductor film" refers to the region up to the detection depth that can be measured using the above X-ray photoelectron spectroscopy for any surface, specifically, the region extending about 5 nm in the depth direction from any surface. In addition, in the present disclosure, the main component means a component having a content exceeding 50% by mass.

[0017] (2) In (1) above, the metal element may be nickel, aluminum, copper, or a combination thereof. By including nickel, aluminum, copper, or a combination thereof as the metal element in the conductor film, the conductivity of the conductor can be further improved.

[0018] (3) In (1) or (2) above, the conductor film may further contain a calcium compound, a fluorine compound, or a combination thereof. By further containing a calcium compound in the conductor film, when the lead wire for non-aqueous electrolyte battery is used in a non-aqueous electrolyte battery, the stability of the conductor film against the decomposition products of the non-aqueous electrolyte components in the non-aqueous electrolyte battery is improved, so that excellent corrosion resistance can be achieved. By further containing a fluorine compound in the conductor film, the formation of a stable passivation film is promoted, so that the corrosion resistance can be further improved.

[0019] (4) In any of (1) to (3) above, the average thickness of the conductor film may be 1 nm or more and 50 nm or less. When the average thickness of the conductor film is 1 nm or more and 50 nm or less, the corrosion resistance of the conductor is good.

[0020] (5) In any of (1) to (4) above, the acid modification rate of the resin component may be 0.10% by mass or more and 0.50% by mass or less. When the acid modification rate of the resin component is 0.10% by mass or more and 0.50% by mass or less, the adhesion strength between the conductor and the insulating film can be further improved.

[0021] (6) In any of (1) to (5) above, the average thickness of the insulating film may be 0.05 mm or more and 0.50 mm or less. The average thickness of the insulating film is 0.05 mm or more and 0.50 mm or less, which allows the gap between the insulating film and the sealed container to be sufficiently filled, and also reduces the amount of moisture that penetrates the insulating film from the atmosphere into the interior of the non-aqueous electrolyte battery.

[0022] (7) In any of (1) to (6) above, the average thickness of the innermost layer may be 0.01 mm or more and 0.25 mm or less. The average thickness of the innermost layer being 0.01 mm or more and 0.25 mm or less improves adhesion to the conductor and suppresses the amount of moisture that penetrates the insulating film from the atmosphere into the interior of the non-aqueous electrolyte battery.

[0023] (8) In any of (1) to (7) above, the conductor may be nickel, nickel-plated metal, nickel-phosphorus alloy plated metal, aluminum, or aluminum alloy. The conductor being nickel, nickel-plated metal, nickel-phosphorus alloy plated metal, aluminum, or aluminum alloy can improve conductivity, potential resistance, etc.

[0024] (9) In any of (1) to (8) above, in the photoelectron spectrum of the outermost surface of the conductive film obtained by X-ray photoelectron spectroscopy, the difference A between the photoelectron intensity at 577.3 (eV) and the background may be considered as the number of chromium atoms contained in chromium(III) hydroxide, the difference B between the photoelectron intensity at 576.1 (eV) and the background may be considered as the number of chromium atoms contained in chromium(III) oxide, and the difference C between the photoelectron intensity at 579.8 (eV) and the background may be considered as the number of chromium atoms contained in chromium(III) fluoride, and the ratio of the number of chromium atoms contained in chromium hydroxide to the number of chromium atoms contained in the trivalent chromium compound may be A / (A+B+C). In other words, when the photoelectron spectrum of the conductive coating is obtained by X-ray photoelectron spectroscopy, with the binding energy value of the measured electrons to the atomic nucleus on the horizontal axis and the photoelectron intensity on the vertical axis, the ratio of the number of chromium atoms contained in the chromium hydroxide to the number of chromium atoms contained in the trivalent chromium compound at the outermost surface of the conductive coating can be determined as follows, thereby allowing for a concise and accurate understanding of the state of the outermost surface of the conductive coating.

[0025] Based on "Applied Surface Science 553 (2021) 149437", the peak positions of chromium(III) hydroxide (Cr(OH)3) and chromium(III) oxide (Cr2O3) are assumed to be 577.3 eV and 576.1 eV, respectively, in the Cr2p3 spectrum obtained by XPS analysis. Furthermore, based on "Surf. Interface Anal. 23 (1995) 887", chromium(III) fluoride (CrF3) is assumed to be 579.8 eV. Specifically, the photoelectron spectrum of the conductive coating is measured using the following procedure. [1] Binding energy correction In the measurement of the photoelectron spectrum of the conductive coating using the above X-ray photoelectron spectroscopy method, the measurement interval on the horizontal axis is set to 0.1 eV. First, the photoelectron spectrum of C1s is measured in the range of 278 eV to 298 eV. Next, a correction is made by subtracting or adding the bond energy on the horizontal axis so that the bond energy of the maximum peak in the obtained C1s range is 284.8 eV. The same correction is applied to other elements (Cr2p3) as to C1s. [2] Smoothing The measurement range for the Cr2p3 spectrum is set to 582 eV to 570 eV (with a background of 581 eV to 572 eV). The photoelectron intensities for chromium(III) hydroxide, chromium(III) oxide, and chromium(III) fluoride are calculated as the average of three points: the photoelectron intensity at the measurement point in the Cr2p3 spectrum and the photoelectron intensities at the measurement intervals before and after that point. The vertical axis of the obtained photoelectron spectrum represents relative values, shown as relative values ​​with the maximum value of the measurement range set to 1. [3] Calculation of A / (A+B+C) When analyzing the obtained spectra of chromium(III) hydroxide, chromium(III) oxide, and chromium(III) fluoride, the baseline is set as a straight line with endpoints of, for example, 581 eV and 572 eV. Then, A, B, and C are defined as the values ​​obtained by subtracting the baseline intensity at the peak position from the photoelectron intensities of 577.3 eV, 576.1 eV, and 579.8 eV. Then, A / (A+B+C) is calculated as the ratio of the number of chromium atoms contained in the chromium hydroxide to the number of chromium atoms contained in the trivalent chromium compound.

[0026] (10) The non-aqueous electrolyte battery of the present disclosure also comprises a sealed container, a plurality of lead wires for the non-aqueous electrolyte battery arranged to extend from the inside to the outside of the sealed container, and a non-aqueous electrolyte.

[0027] The non-aqueous electrolyte battery, by having multiple lead wires for the non-aqueous electrolyte battery, can suppress delamination between the conductor and the insulating film and improve airtightness.

[0028] [Details of the embodiments of this disclosure] The lead wires for non-aqueous electrolyte batteries and the non-aqueous electrolyte batteries related to this disclosure will be described in detail below.

[0029] <Lead wire for non-aqueous electrolyte battery> Figure 1 is a perspective view of a lead wire for a non-aqueous electrolyte battery according to one embodiment of the present disclosure. Figure 2 is a partial cross-sectional view of a lead wire for a non-aqueous electrolyte battery according to one embodiment of the present disclosure. As shown in Figures 1 and 2, the lead wire 1 for the non-aqueous electrolyte battery comprises a conductor 3 and an insulating film 5 having one or more layers and covering at least a portion of the outer surface of the conductor 3. The conductor 3, having one end 4a and the other end 4b, also has a conductor coating 9 that covers at least a portion of its surface. In this embodiment, the insulating film 5 comprises an innermost 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 3 corresponds to a lead conductor.

[0030] (conductor) The conductor 3 is connected to the electrodes of a non-aqueous electrolyte battery. From the viewpoint of conductivity, the material of this conductor 3 can be, for example, metal materials such as aluminum, titanium, nickel, copper, aluminum alloys, titanium alloys, nickel alloys, and copper alloys, as well as nickel-plated metals and nickel-phosphorus alloy plated metals obtained by plating these metal materials with nickel. Among these, the material used to form the conductor 3 connected to the negative electrode of a non-aqueous electrolyte battery may be nickel, nickel-plated metal, or nickel-phosphorus alloy plated metal. On the other hand, the material used to form the conductor 3 connected to the positive electrode may be aluminum or aluminum alloys from the viewpoint of potential resistance, high conductivity, and cost.

[0031] The lower limit of the average thickness of conductor 3 may be 0.10 mm. When the average thickness of conductor 3 is 0.10 mm or more, a sufficient current can be supplied for practical use as a battery. Furthermore, the lower limit of the average thickness of conductor 3 may be 0.15 mm or 0.20 mm. On the other hand, the upper limit of the average thickness of conductor 3 is not particularly limited and can be set appropriately according to the capacity of the non-aqueous electrolyte battery, for example. For example, the upper limit of the average thickness may be 5.00 mm. When the average thickness of conductor 3 is 5.00 mm or less, resistive heat generation in the lead wire portion can be suppressed even when rapid charging and discharging is performed on the lead wire. Furthermore, the upper limit of the average thickness of conductor 3 may be 4 mm. Note that the "average thickness" of conductor 3 is the average value of the thickness measurements taken at 10 points. Hereafter, "average thickness" is synonymous.

[0032] (Conductive coating) The conductive coating 9 covers at least a portion of the surface of the conductor 3. The conductive coating 9 contains a trivalent chromium compound including chromium hydroxide and a metal element. By covering the conductor 3 with a conductive coating containing a trivalent chromium compound including chromium hydroxide and a metal element, the corrosion resistance of the conductor 3 is improved.

[0033] The above-mentioned metal elements may be nickel, aluminum, copper, or a combination thereof. By including nickel, aluminum, copper, or a combination thereof as metal elements in the conductive coating 9, the conductivity of the conductor 3 can be further improved.

[0034] At the outermost surface of the conductive coating 9, the lower limit of the ratio of the number of chromium atoms contained in chromium hydroxide to the number of chromium atoms contained in the trivalent chromium compound is 0.40, but may also be 0.41. If the ratio of the number of chromium atoms contained in chromium hydroxide is less than 0.40, the conductive coating 9 may not be able to form a sufficient amount of hydrogen bonds with the maleic anhydride-modified polypropylene in the innermost layer 6, and the adhesive strength between the conductor 3 and the insulating film 5 may be insufficient. On the other hand, the upper limit of the ratio of the number of chromium atoms contained in chromium hydroxide is 0.85, but may also be 0.84. If the ratio of the number of chromium atoms contained in chromium hydroxide exceeds 0.85, the mechanical strength of the conductive coating 9 may decrease, and the adhesive strength between the conductor 3 and the insulating film 5 may be insufficient. By keeping the ratio of the number of chromium atoms contained in chromium hydroxide within the above range, the conductive coating has a sufficient amount of hydrogen bonds with the maleic anhydride-modified polypropylene in the innermost layer, and the mechanical strength of the conductive coating is good, thus improving the adhesive strength between the conductor and the insulating film.

[0035] The ratio of the number of chromium atoms in chromium hydroxide to the number of chromium atoms in the trivalent chromium compound on the outermost surface of the conductive film 9 can be calculated as follows: In the photoelectron spectrum of the outermost surface of the conductive film, A is considered to be the number of chromium atoms in chromium(III) hydroxide, B is considered to be the number of chromium atoms in chromium(III) oxide, and C is considered to be the number of chromium atoms in chromium(III) fluoride.

[0036] The conductive coating 9 may further contain a calcium compound, a fluorine compound, or a combination thereof. Further inclusion of a calcium compound in the conductive coating 9 improves the stability of the conductive coating 9 against decomposition products of the non-aqueous electrolyte components in the non-aqueous electrolyte battery when the lead wire 1 for the non-aqueous electrolyte battery is used in the non-aqueous electrolyte battery, thus providing excellent corrosion resistance. Further inclusion of a fluorine compound in the conductive coating 9 promotes the formation of a stable passivated coating, further improving corrosion resistance. Examples of calcium compounds include calcium oxide, calcium hydroxide, calcium carbonate, calcium chromate, calcium chromate dihydrate, anhydrous calcium chromate, and calcium aluminate compounds. Examples of fluorine compounds include calcium fluoride, chromium fluoride, aluminum fluoride, and copper fluoride. The calcium compound and fluorine compound in the conductive coating 9 can be confirmed by XPS.

[0037] The lower limit of the average thickness of the conductive coating 9 may be 1 nm or 3 nm. A conductive coating 9 with an average thickness of 1 nm or more ensures sufficient corrosion resistance of the conductor 3. On the other hand, the upper limit of the average thickness of the conductive coating 9 may be 50 nm or 20 nm. A conductive coating 9 with an average thickness of 50 nm or less suppresses density reduction due to crack formation in the conductive coating 9, thereby maintaining better corrosion resistance. The average thickness of the conductive coating 9 can be measured by analyzing the elements present on the surface of the conductor 3 coated with the conductive coating 9 using XPS.

[0038] (Insulating film) The insulating film 5 is used as an insulating film for the lead wire 1 for a non-aqueous electrolyte battery. The insulating film 5 has one or more insulating layers and is laminated on the outer surface of the conductor 3 so as to cover at least a portion of the outer surface of the conductor 3. By having one or more insulating layers 3 in the insulating film 5, various functions can be provided depending on the purpose of the lead wire 1 for the non-aqueous electrolyte battery. The lead wire 1 for a non-aqueous electrolyte battery in this embodiment includes an insulating film 5 having three insulating layers 3.

[0039] The lower limit of the average thickness of the insulating film 5 may be 0.05 mm. An average thickness of 0.05 mm or more ensures that the gap between the insulating film 5 and the sealing container 11, created by the step difference equal to the thickness of the conductor 3, is reliably sealed by filling it with the insulating film 5. Furthermore, the lower limit of the average thickness of the insulating film 5 may be 0.08 mm or 0.10 mm. On the other hand, the upper limit of the average thickness of the insulating film 5 may be 0.50 mm. An average thickness of 0.50 mm or less reduces the amount of moisture that penetrates the insulating film 5 from the atmosphere into the non-aqueous electrolyte battery 10, thereby suppressing the deterioration of the non-aqueous electrolyte battery. Furthermore, the upper limit of the average thickness of the insulating film 5 may be 0.40 mm or 0.30 mm. Here, in this disclosure, the average thickness of the insulating film 5 is the average value of the thickness measurements taken at 10 points on the largest surface area on the outer surface of the insulating film 5.

[0040] In this embodiment, the insulating film 5 has an innermost 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.

[0041] (Innermost layer) The innermost layer 6 is laminated on the surface of the conductor coating 9. The insulating film 5, by having the innermost layer 6, can suppress corrosion of the conductor 3.

[0042] The innermost layer 6 is mainly composed of a resin component containing maleic anhydride-modified polypropylene (maleic anhydride-modified PP). Because the innermost layer 6 is mainly composed of a resin component containing maleic anhydride-modified polypropylene, it has good adhesion to the conductor coating 9.

[0043] The lower limit of the acid modification rate of the above resin component is 0.02% by mass, but it may also be 0.10% by mass. An acid modification rate of 0.02% by mass or higher enhances the adhesion between the innermost layer 6 and the conductor coating 9, providing sufficient resistance to non-aqueous electrolytes. On the other hand, the upper limit of the acid modification rate of the above resin component is 0.50% by mass, but it may also be 0.40% by mass. An acid modification rate of 0.50% by mass or lower allows the maleic anhydride-modified groups to suppress corrosion of the conductor 3, resulting in good corrosion resistance. The above acid denaturation rate was determined by infrared spectroscopy (transmitted FT-IR) at 1710 cm². -1 It is calculated by taking the mass of carboxyl groups measured from the peak area and converting it from the average thickness of the innermost six layers based on an appropriate calibration curve.

[0044] The melting point of maleic anhydride-modified polypropylene may be between 130°C and 170°C, or between 130°C and 150°C. If the melting point of maleic anhydride-modified polypropylene is below 130°C, its heat resistance may decrease. On the other hand, if the melting point of maleic anhydride-modified polypropylene exceeds 170°C, the amount of heat required to melt it is large, and it may not melt sufficiently, potentially resulting in insufficient adhesion between the innermost layer 6 and the conductor 3.

[0045] The lower limit of the content of maleic anhydride-modified polypropylene in the innermost layer 6 may be 0.1% by mass or 0.5% by mass. If the content of maleic anhydride-modified polypropylene is less than 0.1% by mass, there is a risk that the material properties may not be sufficient for practical use.

[0046] In the innermost layer 6, the resin component may contain a thermoplastic resin other than maleic anhydride-modified polypropylene, to the extent that it does not impair the effects of this disclosure. Examples of thermoplastic resins other than maleic anhydride-modified polypropylene include polyolefins such as polypropylene and polyethylene. The innermost layer 6 may also contain other known additives. Examples of known additives include antioxidants, flame retardants, tackifiers, lubricants, fillers, crystallization accelerators, and colorants.

[0047] The lower limit of the average thickness of the innermost layer 6 may be 0.01 mm. A minimum average thickness of 0.01 mm for the innermost layer 6 ensures sufficient adhesion to the conductor 3. Alternatively, the lower limit of the average thickness of the innermost layer 6 may be 0.02 mm or 0.03 mm. On the other hand, the upper limit of the average thickness of the innermost layer 6 may be 0.25 mm. A minimum average thickness of 0.25 mm for the innermost layer 6 reduces the amount of moisture that penetrates the insulating film 5 from the atmosphere into the non-aqueous electrolyte battery, thereby suppressing battery degradation. Alternatively, the upper limit of the average thickness of the innermost layer 6 may be 0.22 mm or 0.20 mm. In this disclosure, the average thickness of the innermost layer 6 is the average of the thickness measurements taken at 10 points on the largest surface area within the outer periphery of the innermost layer 6.

[0048] (First insulating layer) The first insulating layer 8 is positioned furthest from the conductor 3 and is formed of a thermoplastic resin. The first insulating layer 8 is laminated on the outermost surface of the insulating film 5 and on the surface of the second insulating layer 7. The first insulating layer 8 may be mainly composed of a resin that is easily melted at the heat sealing temperature when the opening of the sealed container is heat-sealed (heat-fused), or it may be mainly composed of polyolefin.

[0049] Examples of polyolefins include polypropylene, polyethylene, and their derivatives. More specifically, examples 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, and low-crystalline propylene-ethylene copolymer. The first insulating layer 8 may contain multiple resins. The polyolefin may be polypropylene, and the polypropylene may be random polypropylene with a melting point of 120°C to 155°C and an MFR of 3g / 10min to 15g / 10min. The advantage of using random polypropylene as the polyolefin is that it can exhibit sufficient adhesion to the second insulating layer 7 and the innermost resin layer of the sealed container.

[0050] The lower limit of the polyolefin content in the first insulating layer 8 may be 70% by mass. If the polyolefin content is less than 70% by mass, there is a risk that the material properties may not be sufficient for practical use. Furthermore, the lower limit of the polyolefin content in the first insulating layer 8 may be 80% by mass, 90% by mass, or 100% by mass.

[0051] The first insulating layer 8 may contain thermoplastic resins other than the polyolefins described above, to the extent that they do not impair the effects of the present disclosure.

[0052] The first insulating layer 8 may contain other known additives to the extent that they do not impair the effects of the present disclosure. Examples of known additives include antioxidants, flame retardants, tackifiers, lubricants, fillers, crystallization accelerators, and colorants.

[0053] The lower limit of the average thickness of the first insulating layer 8 may be 25 μm. If the average thickness of the first insulating layer 8 is less than 25 μm, the strength of the first insulating layer 8 may not be sufficient. Furthermore, the lower limit of the average thickness of the first insulating layer 8 may be 30 μm or 40 μm. On the other hand, the upper limit of the average thickness of the first insulating layer 8 may be 250 μm. If the average thickness of the first insulating layer 8 exceeds 250 μm, the amount of moisture that penetrates the insulating film 5 from the atmosphere into the interior of the non-aqueous electrolyte battery may increase, potentially accelerating the deterioration of the battery. Here, in this disclosure, the average thickness of the first insulating layer 8 is the average value of the thickness measurements taken at 10 points on the surface with the largest area on the outer surface of the first insulating layer 8.

[0054] (Second insulating layer) The insulating film 5 may have a second insulating layer 7 between the first insulating layer 8 and the innermost layer 6. The second insulating layer 7 is laminated on the inner surface of the first insulating layer 8. The second insulating layer 7 may contain a crosslinked polyolefin or a polyolefin with a higher melting point than the innermost layer 6. By including a crosslinked polyolefin or a polyolefin resin with a higher melting point than the innermost layer 6 in the second insulating layer 7, it is less likely to melt at the heat sealing temperature when the opening of the sealed container is heat sealed, thereby suppressing short circuits between the metal layer of the sealed container and the conductor.

[0055] Examples of polyolefins in the above-mentioned crosslinked polyolefin include polypropylene, polyethylene, and derivatives thereof.

[0056] The high-melting-point polyolefin may be polypropylene with a melting point of 155°C or higher, and may be homopolypropylene, block polypropylene, thermoplastic olefin elastomer (TPO), etc.

[0057] The second insulating layer 7 may contain thermoplastic resins other than the crosslinked polyolefins described above, and may also contain other known additives, to the extent that they do not impair the effects of the present disclosure. Examples of known additives include antioxidants, flame retardants, tackifiers, lubricants, fillers, crystallization accelerators, and colorants.

[0058] The lower limit of the average thickness of the second insulating layer 7 may be 25 μm. If the average thickness of the second insulating layer 7 is less than 25 μm, the strength of the second insulating layer 7 may not be sufficient. Furthermore, the lower limit of the average thickness of the second insulating layer 7 may be 30 μm or 40 μm. On the other hand, the upper limit of the average thickness of the second insulating layer 7 may be 250 μm. If the average thickness of the second insulating layer 7 exceeds 250 μm, the amount of moisture that penetrates the insulating film 5 from the atmosphere into the interior of the non-aqueous electrolyte battery may increase. Here, in this disclosure, the average thickness of the second insulating layer 7 is the average value of the thickness measurements taken at 10 points on the surface with the largest area on the outer surface of the second insulating layer 7.

[0059] [Manufacturing method for lead wires for non-aqueous electrolyte batteries] The method for manufacturing the lead wires for the non-aqueous electrolyte battery is not particularly limited and can be manufactured by known methods.

[0060] First, a treatment solution is applied to at least a portion of the conductor's surface, and a chemical conversion treatment (chromate treatment) is performed using the following method to coat the conductor with a conductor film. First, the circumferential surface of the conductor is degreased. When the conductor is formed, oily components may adhere to its surface, and the degreasing is performed to remove these oily components and oils. Degreasing can be carried out by coating or immersing the conductor in an organic solvent, surfactant, acid, or alkaline solution. Next, after washing and removing the organic solvent, surfactant, acid, or alkaline solution and drying the surface, the metal surface is chemically treated using a solution mainly composed of chromate.

[0061] Examples of acidic compounds used for degreasing include hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, phosphoric acid, sulfamic acid and other inorganic acids, citric acid, gluconic acid, oxalic acid, tartaric acid, formic acid, hydroxyacetic acid, EDTA (ethylene diamine tetraacetic acid), and ammonium thioglycolate. Furthermore, examples of alkaline compounds include sodium salts such as sodium hydroxide (NaOH), sodium carbonate (Na2CO3), baking soda (NaHCO3), sodium sulfate (Na2SO4·10H2O), and sodium sesquicarbonate (Na2CO3·NaHCO3·2H2O); silicates such as sodium orthosilicate (2Na2O·SiO2, 10%~40% moisture content) and sodium metasilicate (2Na2O·SiO2·9H2O); and phosphates such as monosodium phosphate (NaH2PO4), sodium pyrophosphate (Na4P2O7), disodium phosphate (Na2HPO4), sodium hexametaphosphate ((NaPO3)6), and trisodium phosphate (Na3PO4).

[0062] The chemical conversion treatment is performed by applying and drying the treatment solution to the conductor, such as by immersing the conductor in the treatment solution, spraying the treatment solution onto the conductor, or using a roll coating method. In the chemical conversion treatment, at least the insulating film coating may be treated, but it is desirable to treat the entire circumference of the conductor using methods such as immersion, shower, or roll coating.

[0063] As the treatment solution for chemical conversion, an aqueous solution containing 5.0 g / L of chromium chloride hexahydrate and 170 g / L of potassium formate is used. The conductor is subjected to the above treatment solution at 45°C with a current density of 10 A / dm². 2 The coating is applied by cathode electrolysis for 30 seconds under these conditions. Next, after drying, it is baked at a heating temperature of 100°C to 300°C to form a conductive coating.

[0064] Next, an insulating film is applied to at least a portion of the outer surface of the conductor covered by the conductive coating. The method for manufacturing the insulating film is not particularly limited. For example, a forming resin composition containing the respective resin components and additives of each 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 each insulating layer, each insulating layer can be made into a film by extrusion molding such as T-die molding or inflation molding. Then, the insulating layers are stacked and bonded together by heat lamination using a hot roll. In addition, multiple insulating layers can be formed simultaneously using the inflation method by co-extrusion or the T-die method. Furthermore, an extrusion lamination method can be used in which molten resin is laminated on a single-layer film. The film-like insulating film is cut to a predetermined size and coated to at least a portion of the outer surface of the conductor by heat and pressure bonding from both sides of the conductor using a thermocompression bonding method. Furthermore, insulating layers can be produced not only by extrusion molding but also by injection molding. In injection molding, the conductor can be coated by injecting resin after mounting the conductor in the mold, and two-color molding can be used when forming multiple layers.

[0065] The lead wires for non-aqueous electrolyte batteries exhibit excellent resistance to the non-aqueous electrolyte of the non-aqueous electrolyte battery.

[0066] <Nonaqueous electrolyte battery> The non-aqueous electrolyte battery 10 comprises the lead wire 1 for the non-aqueous electrolyte battery described above and a non-aqueous electrolyte. Examples of non-aqueous electrolyte batteries include lithium-ion secondary batteries.

[0067] Figure 3 is a perspective view showing an example of a non-aqueous electrolyte battery equipped with lead wires for the non-aqueous electrolyte battery. Figure 4 is a schematic partial cross-sectional view showing one embodiment of the non-aqueous electrolyte battery. The non-aqueous electrolyte battery (non-aqueous electrolyte secondary battery) 10 shown in Figures 3 and 4 comprises a plate-shaped positive electrode, a plate-shaped negative electrode, and a non-aqueous electrolyte (not shown), a sealed container 11, and a plurality of, specifically two, lead wires 1 for the non-aqueous electrolyte battery. The lead wires 1 for the non-aqueous electrolyte battery are the lead wires for the non-aqueous electrolyte battery described above. As described above, the lead wires 1 for the non-aqueous electrolyte battery in this embodiment have an insulating film 5 with an innermost layer 6, a second insulating layer 7, and a first insulating layer 8. The non-aqueous electrolyte battery 10 has a substantially rectangular sealed container 11 and two lead wires 1 for the non-aqueous electrolyte battery extending from the inside to the outside of the sealed container 11. The conductor 3 and the sealed container 11 are connected via the insulating film 5 at the seal portion 13 of the sealed container 11. The sealed container 11 is a container that houses the positive electrode, negative electrode, separator, and non-aqueous electrolyte in a sealed state.

[0068] Positive and negative electrodes (not shown) are stacked via a separator to form a stacked electrode group. This stacked electrode group and a non-aqueous electrolyte are housed in a sealed container 11. Within this container 11, the stacked electrode group is immersed in the electrolyte. The container 11 is formed from a sheet body, as will be described later. In the container 11, the seal portion 13 around two sheet bodies or one folded sheet body is heat-sealed.

[0069] As shown in Figure 4, in the two lead wires 1 for non-aqueous electrolyte batteries, one lead wire 1 is arranged such that one end 4a of its conductor 3 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 is arranged such that one end 4a of its conductor 3 is exposed from the sealed container 11 and the other end 4b is connected to the negative electrode inside the sealed container 11.

[0070] The encapsulation container 11 is not laminated at both ends of the conductor 3, i.e., one end 4a and the other end 4b. One end 4a of the conductor 3 is exposed from the encapsulation container 11. On the other hand, an internal connection lead wire 14 is connected to the other end 4b of the conductor 3 of the positive electrode non-aqueous electrolyte battery lead wire 1 via a solder joint 15, and this internal connection lead wire 14 connects 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 non-aqueous electrolyte battery lead wire 1 via a solder joint 15, and this internal connection lead wire 14 connects to a negative electrode (not shown). As shown in Figure 4, the intermediate portions of these non-aqueous electrolyte battery lead wires 1 are sandwiched between a sheet body which is the encapsulation container 11 via an insulating film 5, and in this portion, the encapsulation container 11 and the first insulating layer 8 of the multiple non-aqueous electrolyte battery lead wires 1 are heat-fused together.

[0071] The positive and negative electrodes described above are typically laminates in which an active material layer containing an active material is laminated onto the surface of a current collector such as a metal foil. The positive and negative electrodes are usually plate-shaped, but they may also be in shapes other than plates.

[0072] The separator described above is typically an insulating and porous film. This separator is impregnated with a non-aqueous electrolyte.

[0073] A non-aqueous electrolyte contains a non-aqueous solvent and an electrolyte salt dissolved in this non-aqueous solvent.

[0074] As shown in Figure 4, the sealing container 11 is composed of a sheet body in which the innermost resin layer 27, the metal layer 25, and the outermost resin layer 26 are laminated in that order. The sealing container 11 is formed by overlapping two sheet bodies and heat-sealing three sides other than the side through which the conductor passes. At the sealing portion 13, the conductors 3 of each non-aqueous electrolyte battery lead wire 1 are bonded to the sealing container 11 with an insulating film 5 in between. At this point, the innermost resin layer 27 of the sealing container 11 and the first insulating layer 8 of each non-aqueous electrolyte battery lead wire 1 are heat-fused together.

[0075] The innermost resin layer 27 is laminated directly onto the inner surface of the metal layer 25. The innermost resin layer 27, located inside the sealed container 11, may be made of an insulating resin that does not dissolve in a non-aqueous electrolyte and melts when heated. As the innermost resin layer 27, for example, polyolefin, acid-modified polyolefin, or acid-modified styrene elastomer can be used. Among these, polypropylene is preferred as the innermost resin layer 27. The average thickness of the innermost resin layer 27 may be in the range of approximately 10 μm to 500 μm.

[0076] 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 inside of the battery. The metal layer 25 is formed from a metal such as aluminum foil. The metal layer 25 is mainly composed of metal. Examples of this metal include aluminum, copper, stainless steel, and titanium, with aluminum being preferred among these. Although the metal layer 25 is substantially formed from metal, it may also contain additives other than metal. The metal layer 25 is in the form of a film and may be formed from metal foil or aluminum alloy foil. The average thickness of the metal layer 25 may be about 10 μm to 50 μm.

[0077] The outermost resin layer 26 has the function of protecting the outer surface of the metal layer 25 and providing insulation. The outermost resin layer 26, located on the outside of the sealed container, is usually made of resin as the main component as an insulating material. Examples of resins that form the outermost resin layer 26 include polyethylene terephthalate (PET), polyamide, polyester, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicon resin, phenolic resin, polyetherimide, polyimide, and mixtures or copolymers thereof. The outermost resin layer 26 may be composed of multiple layers with an adhesive layer containing, for example, polyethylene terephthalate, polyamide, etc. The average thickness of the outermost resin layer 26 may be in the range of 10 μm to 50 μm.

[0078] In the non-aqueous electrolyte battery 10, as described above, one end of the lead wire 1 for the non-aqueous electrolyte battery, i.e., one end 4a of the conductor 3, is exposed from the sealing container 11 and sealed by the sealing container 11. Specifically, the lead wire 1 for the non-aqueous electrolyte battery is positioned so that the innermost resin layer of the sealing container 11 and the insulating film 5 of the lead wire 1 for the non-aqueous electrolyte battery are in direct contact. Furthermore, with the lead wire 1 for the non-aqueous electrolyte battery positioned in this manner, the innermost resin layer 27 of the seal portion 13 of the sealing container 11 and the first insulating layer 8 of the lead wire 1 for the non-aqueous electrolyte battery are heat-fused together. As a result, the stacked electrode group, consisting of the positive electrode, negative electrode, and separator, which is immersed in the non-aqueous electrolyte, can be sealed within the sealing container 11.

[0079] [Method for manufacturing non-aqueous electrolyte battery] A method for manufacturing a non-aqueous electrolyte battery according to one embodiment of this disclosure can be appropriately selected from known methods. The method for manufacturing the non-aqueous electrolyte battery includes, for example, the steps of preparing lead wires for the non-aqueous electrolyte battery, preparing a group of stacked electrodes, preparing a non-aqueous electrolyte, and housing the group of stacked electrodes to which the lead wires for the non-aqueous electrolyte battery are connected and the non-aqueous electrolyte in a sealed container.

[0080] The non-aqueous electrolyte battery, by having multiple lead wires for the non-aqueous electrolyte battery, can suppress delamination between the conductor and the insulating film and improve airtightness.

[0081] [Other embodiments] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure is not limited to the configurations of the embodiments described above, but is indicated by the claims, and all modifications within the meaning and scope of the claims are intended to be included.

[0082] In the above embodiment, the lead wire for the non-aqueous electrolyte battery had a three-layer insulating film having an innermost layer, a second insulating layer, and a first insulating layer. However, the lead wire for the non-aqueous electrolyte battery may have a two-layer insulating film that does not include a second insulating layer. Alternatively, the lead wire for the non-aqueous electrolyte battery may have a multilayer insulating film having one or more intermediate layers inside the second insulating layer. [Examples]

[0083] 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.

[0084] [Exam No. 1] (Fabrication of lead conductors) As the base material for the lead conductor, an oxygen-free copper plate (C1020) with a length of 100 mm, a width of 45 mm, and an average thickness of 0.2 mm was used. As a pretreatment, the base material was immersed in a sodium hydroxide aqueous solution (40 g / L) at 25°C, and the current density was set to 1.0 A / dm². 2 Cathodic electrolytic degreasing was performed. The degreased substrate was then washed with running water. Next, the washed substrate was immersed in a 10% by mass sulfuric acid aqueous solution at 25°C for 30 seconds to perform acid activation. After acid activation, the substrate was washed with running water. Next, nickel tetrahydrate amide sulfate (350 g / L), nickel hexahydrate (30 g / L), and boric acid (30 g / L) were mixed to obtain a nickel plating solution. The substrate, after acid activation, was immersed in the nickel plating solution at 50°C, and a current density of 5.0 A / dm² was applied. 2 Plating was performed for 120 seconds. After plating, the substrate was washed with running water to obtain a lead conductor made of nickel-plated copper (metal with nickel plating).

[0085] (Formation of conductive coating) A surface treatment solution was obtained by mixing chromium chloride hexahydrate (5.0 g / L) and potassium formate (170 g / L) in pure water. The lead conductor was immersed in the surface treatment solution at 45°C, and a current density of 10 A / dm² was obtained. 2Cathodic electrolysis was performed for 30 seconds. After cathodic electrolysis, the lead conductor was washed with running water and dried in a 100°C constant temperature bath for 180 seconds to obtain a lead conductor with a conductive coating. The ratio of the number of chromium atoms in the chromium hydroxide to the number of chromium atoms in the trivalent chromium compound at the outermost surface of this conductive coating was 0.50.

[0086] (Fabrication of insulating film) A two-layer insulating film comprising an innermost layer and a first insulating layer was fabricated. First, the resin compositions for the innermost layer and the first insulating layer were prepared using a mixing apparatus. (1) Innermost layer 100 parts by mass of Prime PolyPro F227D (melting point 142°C, MFR7) manufactured by Prime PolyPro as random polypropylene (random PP) and 1 part by mass of SIIgroup's POLYBOND3000 (melting point 157°C, acid modification rate 1.2% by mass) as maleic anhydride modified polypropylene were kneaded in a twin-screw kneader to obtain a resin component with an acid modification rate of 0.01% by mass. (2) First insulating layer As the material for the resin composition of the first insulating layer, random polypropylene: Prime PolyPro F227D (MFR 7g / 10 min, melting point 140℃) manufactured by Prime PolyPro was used. (3) Fabrication of insulating film Next, using a coat hanger type two-layer T-die film deposition machine equipped with two single-screw extruders, the innermost layer resin composition was fed into the first extruder and the first insulating layer resin composition into the second extruder. By co-extruding, two insulating films were obtained, laminated in the order of innermost layer resin composition / first insulating layer resin composition. The average thickness of the innermost layer was 50 μm, and the average thickness of the first insulating layer was 100 μm.

[0087] (Fabrication of lead wires for non-aqueous electrolyte batteries) Next, the two-layer insulating film obtained 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 0.2 MPa. This yielded lead wire No. 1 for a non-aqueous electrolyte battery.

[0088] [Exam No. 2] In the preparation of the insulating film, a lead wire for a non-aqueous electrolyte battery was obtained in the same manner as in Test No. 1, except that 100 parts by mass of "Prime PolyPro F227D" manufactured by Prime PolyPro Co., Ltd. as random polypropylene and 5 parts by mass of "POLYBOND3000" manufactured by SIIgroup Co., Ltd. as maleic anhydride modified polypropylene were used as materials for the innermost layer resin composition to obtain a resin component with an acid modification rate of 0.06% by mass.

[0089] [Exam No. 3] In the preparation of the insulating film, a lead wire for a non-aqueous electrolyte battery was obtained in the same manner as in Test No. 1, except that 100 parts by mass of "Prime PolyPro F227D" manufactured by Prime PolyPro Co., Ltd. as random polypropylene and 15 parts by mass of "POLYBOND3000" manufactured by SIIgroup Co., Ltd. as maleic anhydride modified polypropylene were used as materials for the innermost layer resin composition to obtain random PP with an acid modification rate of 0.18% by mass.

[0090] [Exam No. 4] In the preparation of the insulating film, a lead wire for a non-aqueous electrolyte battery was obtained in the same manner as in Test No. 1, except that 100 parts by mass of "Prime PolyPro F227D" manufactured by Prime PolyPro Co., Ltd. as random polypropylene and 40 parts by mass of "POLYBOND3000" manufactured by SIIgroup Co., Ltd. as maleic anhydride-modified polypropylene were used as materials for the innermost layer resin composition to obtain random PP with an acid modification rate of 0.48% by mass.

[0091] [Exam No. 5] In the preparation of the insulating film, a lead wire for a non-aqueous electrolyte battery was obtained in the same manner as in Test No. 1, except that 100 parts by mass of "Prime PolyPro F227D" manufactured by Prime PolyPro Co., Ltd. as random polypropylene and 50 parts by mass of "POLYBOND3000" manufactured by SIIgroup Co., Ltd. as maleic anhydride-modified polypropylene were used as materials for the innermost layer resin composition to obtain random PP with an acid modification rate of 0.60% by mass.

[0092] [Exam No. 6] In the formation of the conductive coating, the lead conductor after cathode electrolysis was washed with running water and dried in a 100°C constant temperature bath for 30 seconds, thereby obtaining a lead conductor having a conductive coating in which the ratio of the number of chromium atoms in the chromium hydroxide to the number of chromium atoms in the trivalent chromium compound on the outermost surface of the conductive coating was 0.83. Otherwise, a lead wire for a non-aqueous electrolyte battery was obtained in the same manner as in No. 3.

[0093] [Exam No. 7] In the formation of the conductive coating, the lead conductor after cathode electrolysis was washed with running water and dried in a constant temperature bath at 80°C for 20 seconds, thereby obtaining a lead conductor having a conductive coating in which the ratio of the number of chromium atoms in the chromium hydroxide to the number of chromium atoms in the trivalent chromium compound on the outermost surface of the conductive coating was 0.88. Otherwise, a lead wire for a non-aqueous electrolyte battery was obtained in the same manner as in No. 3.

[0094] [Exam No. 8] In the formation of the conductive coating, the lead conductor after cathode electrolysis was washed with running water and dried in a constant temperature bath at 250°C for 3600 seconds, thereby obtaining a lead conductor having a conductive coating in which the ratio of the number of chromium atoms in the chromium hydroxide to the number of chromium atoms in the trivalent chromium compound on the outermost surface of the conductive coating is 0.38. Otherwise, a lead wire for a non-aqueous electrolyte battery was obtained in the same manner as in No. 3.

[0095] [Exam No. 9] A flat conductor made of aluminum plate with a length of 100 mm, a width of 45 mm, and an average thickness of 0.4 mm was used as the base material for the lead conductor. For the formation of the conductor coating, chromium chloride hexahydrate (5.0 g / L) and potassium formate (170 g / L) were mixed with pure water to obtain a surface treatment solution. The lead conductor was immersed in the surface treatment solution at 45°C, and a current density of 10 A / dm² was achieved. 2 Cathodic electrolysis was performed for 10 seconds. After cathodic electrolysis, the lead conductor was washed with running water to obtain a lead conductor having a conductor coating in which the ratio of the number of chromium atoms in the chromium hydroxide to the number of chromium atoms in the trivalent chromium compound at the outermost surface of the conductor coating was 0.57. In addition, a lead wire for a non-aqueous electrolyte battery was obtained in the same manner as in No. 3.

[0096] [Test No. 10] A flat conductor made of an aluminum plate with a length of 100 mm, a width of 45 mm, and an average thickness of 0.4 mm was used as the base material of the lead conductor. In the formation of the conductor coating, chromium chloride hexahydrate (5.0 g / L), potassium formate (170 g / L), and potassium fluoride (5.0 g / L) were mixed in pure water to obtain a surface treatment solution. The lead conductor was immersed in the surface treatment solution at 45 °C, and cathodic electrolysis was performed at a current density of 10 A / dm 2 for 10 seconds. After the cathodic electrolysis, the lead conductor was washed with running water. Except for obtaining a lead conductor having a conductor coating with a ratio of the number of chromium atoms contained in the chromium hydroxide to the number of chromium atoms contained in the trivalent chromium compound on the outermost surface of the conductor coating being 0.41, a lead wire for a non-aqueous electrolyte battery was obtained in the same manner as in No. 3.

[0097] [Test No. 11] In the formation of the conductor coating, chromium chloride hexahydrate (5.0 g / L), potassium formate (170 g / L), and calcium chloride (0.5 g / L) were mixed in pure water to obtain a surface treatment solution. The lead conductor was immersed in the surface treatment solution at 45 °C, and cathodic electrolysis was performed at a current density of 10 A / dm 2 for 30 seconds. After the cathodic electrolysis, the lead conductor was washed with running water and dried in a constant temperature bath at 100 °C for 180 seconds. Except for obtaining a lead conductor having a conductor coating with a ratio of the number of chromium atoms contained in the chromium hydroxide to the number of chromium atoms contained in the trivalent chromium compound on the outermost surface of the conductor coating being 0.53, a lead wire for a non-aqueous electrolyte battery was obtained in the same manner as in No. 2.

[0098] [Test No. 12] In the formation of the conductor coating, chromium chloride hexahydrate (5.0 g / L), potassium formate (170 g / L), and calcium chloride (5.0 g / L) were mixed in pure water to obtain a surface treatment solution. The lead conductor was immersed in the surface treatment solution at 45 °C, and cathodic electrolysis was performed at a current density of 10 A / dm 2Cathodic electrolysis was performed for 30 seconds. After cathodic electrolysis, the lead conductor was washed with running water and dried in a 100°C constant temperature bath for 180 seconds to obtain a lead conductor having a conductor coating in which the ratio of the number of chromium atoms in the chromium hydroxide to the number of chromium atoms in the trivalent chromium compound at the outermost surface of the conductor coating was 0.38. Otherwise, a lead wire for a non-aqueous electrolyte battery was obtained in the same manner as in No. 2.

[0099] [Exam No. 13] As the base material for the lead conductor, an oxygen-free copper plate (C1020) with a length of 100 mm, a width of 45 mm, and an average thickness of 0.2 mm was used. As a pretreatment, the base material was immersed in a sodium hydroxide aqueous solution (40 g / L) at 25°C, and the current density was set to 1.0 A / dm². 2 Cathodic electrolytic degreasing was performed. The degreased substrate was then washed with running water. Next, the washed substrate was immersed in a 25°C sulfuric acid aqueous solution (10% by mass) for 30 seconds to perform acid activation. After acid activation, the substrate was washed with running water. Then, a lead wire for a non-aqueous electrolyte battery was obtained in the same manner as in No. 3, except that the process using nickel plating solution was omitted.

[0100] [evaluation] (The ratio of the number of chromium atoms in the chromium hydroxide mentioned above to the number of chromium atoms in the trivalent chromium compound) The ratio of the number of chromium atoms in the chromium hydroxide to the number of chromium atoms in the trivalent chromium compound at the outermost surface of the conductive coating was measured using X-ray photoelectron spectroscopy. The XPS measurement conditions are as follows. Based on the procedure described above, the ratio of the number of chromium atoms in the chromium hydroxide to the number of chromium atoms in the trivalent chromium compound was calculated from the spectrum obtained under the following measurement conditions. <XPS measurement conditions> Measuring instrument: ULVAC PHI QuanteraSXM X-ray source: AL-Kα X-ray source output: 25W, 15kV Analysis area: 100 μmφ Photoelectron extraction angle: 45° Transmission energy: Narrow 55 eV Measurement range: 570eV~582eV Integration time :Time per step:20ms cycles: 10

[0101] (Method for correcting the binding energy of the spectrum) The photoelectron spectrum of C1s was measured in the 278eV–298eV range. A correction was applied to the bond energy by subtracting or adding it so that the bond energy of the maximum peak in the obtained C1s (278eV–298eV) range was 284.8eV. The same correction was applied to the other elements (Cr2p3) as to C1s.

[0102] (Maleic anhydride modification rate of polypropylene) The rate of maleic anhydride modification of polypropylene was determined by infrared spectral transmission using Thermo Fisher's "Nicolet 8700" at 1710 cm². -1 The mass of carboxyl groups measured from the peak area was calculated by converting it from the average thickness of the innermost layer based on an appropriate calibration curve.

[0103] (Evaluation of resistance to non-aqueous electrolytes) <Peeling test after immersion in electrolyte solution> For Tests No. 1 to No. 13, peel tests were conducted after immersion in the electrolyte. The electrolyte was prepared by mixing ethylene carbonate, diethyl carbonate, and dimethyl carbonate in a 1:1:1 volume ratio, and dissolving lithium hexafluoride phosphate (LiPF6) at a concentration of 1.0 mol / L. After adjusting the water content of this electrolyte to 1000 ppm, the lead wires for non-aqueous electrolyte batteries from Tests No. 1 to No. 13 were immersed in the electrolyte and left in an 80°C constant temperature bath for 4 weeks. Then, peel tests were conducted on Tests No. 1 to No. 13 after immersion in the electrolyte using the following method: One end of the lead conductor and the insulating film of Tests No. 1 to No. 13 were cut and bent at 180°, and then set in a tensile testing machine (Shimadzu Corporation "EX-SX"). The set cut section was pulled at a tensile speed of 50 mm / min to evaluate whether peeling occurred at the interface between the conductor and the insulating film. The results are shown in Table 1.

[0104] [Table 1]

[0105] As shown in Table 1, in the lead wires for non-aqueous electrolyte batteries, the conductor is coated with a conductive film containing a trivalent chromium compound including chromium hydroxide and a metal element, the innermost layer of the insulating film laminated on the surface of the conductive film is mainly composed of a resin component including maleic anhydride-modified polypropylene, the ratio of the number of chromium atoms in chromium hydroxide to the number of chromium atoms in the trivalent chromium compound at the outermost surface of the conductive film is 0.40 or more and 0.85 or less, and the acid modification rate of the resin component is 0.02% by mass or more and 0.50% by mass or less. In Tests No. 2 to No. 4, No. 6, No. 9 to No. 11 and No. 13, there was no peeling at the interface between the conductor and the insulating film in the peel test, and the resistance to non-aqueous electrolyte was good.

[0106] On the other hand, in Test No. 1, where the acid modification rate of the resin component, which is the main component of the innermost layer, was less than 0.02% by mass; in Test No. 5, where the acid modification rate of the resin component exceeded 0.50% by mass; in Test No. 7, where the ratio of the number of chromium atoms contained in chromium hydroxide to the number of chromium atoms contained in the trivalent chromium compound on the outermost surface of the conductor coating exceeded 0.85; and in Tests No. 8 and No. 12, where the ratio of the number of chromium atoms contained in the chromium hydroxide was less than 0.40, peeling was observed at the interface between the conductor and the insulating film during the peeling test, indicating poor resistance to non-aqueous electrolytes.

[0107] The results above demonstrate that the lead wires for non-aqueous electrolyte batteries exhibit excellent resistance to the non-aqueous electrolyte in non-aqueous electrolyte batteries. [Explanation of Symbols]

[0108] 1 Lead wire for non-aqueous electrolyte battery 3 conductors 4a One end 4b Other end 5. Insulating film 6. Innermost layer 7. Second insulating layer 8. First insulating layer 9 Conductor coating 10 Nonaqueous electrolyte battery 11. Encapsulation container 13. Seal part 14. Internal connection lead wires 15 Soldering section 25 metal layer 26. Outermost resin layer 27 Innermost resin layer

Claims

1. A conductor and An insulating film having one or more layers, covering at least a portion of the outer surface of the conductor and Equipped with, The above conductor has a conductive coating that covers at least a portion of its surface, The above conductive coating contains a trivalent chromium compound including chromium hydroxide and a metal element, The ratio of the number of chromium atoms in the chromium hydroxide to the number of chromium atoms in the trivalent chromium compound at the outermost surface of the conductive film is 0.40 or more and 0.85 or less. The insulating film has an innermost layer that is laminated on the surface of the conductive film. The innermost layer described above mainly consists of a resin component containing maleic anhydride-modified polypropylene, Lead wire for non-aqueous electrolyte batteries, wherein the acid modification rate of the above resin component is 0.02% by mass or more and 0.50% by mass or less.

2. Lead wire for a non-aqueous electrolyte battery according to claim 1, wherein the above-mentioned metal element is nickel, aluminum, copper, or a combination thereof.

3. Lead wire for non-aqueous electrolyte battery according to claim 1, further comprising a calcium compound, a fluorine compound, or a combination thereof in the conductor coating.

4. Lead wire for non-aqueous electrolyte battery according to claim 1, wherein the average thickness of the conductor coating is 1 nm or more and 50 nm or less.

5. Lead wire for non-aqueous electrolyte battery according to claim 1, wherein the acid modification rate of the above resin component is 0.10% by mass or more and 0.50% by mass or less.

6. Lead wire for a non-aqueous electrolyte battery according to claim 1, wherein the average thickness of the insulating film is 0.05 mm or more and 0.50 mm or less.

7. Lead wire for a non-aqueous electrolyte battery according to claim 1, wherein the average thickness of the innermost layer is 0.01 mm or more and 0.25 mm or less.

8. Lead wire for a non-aqueous electrolyte battery according to claim 1, wherein the conductor is nickel, nickel-plated metal, nickel-phosphorus alloy plated metal, aluminum, or aluminum alloy.

9. Lead wire for a non-aqueous electrolyte battery according to claim 1, wherein in the photoelectron spectrum of the outermost surface of the conductive film obtained by X-ray photoelectron spectroscopy, the difference A between the photoelectron intensity at 577.3 (eV) and the background is considered to be the number of chromium atoms contained in chromium(III) hydroxide, the difference B between the photoelectron intensity at 576.1 (eV) and the background is considered to be the number of chromium atoms contained in chromium(III) oxide, and the difference C between the photoelectron intensity at 579.8 (eV) and the background is considered to be the number of chromium atoms contained in chromium(III) fluoride, and the ratio of the number of chromium atoms contained in chromium hydroxide to the number of chromium atoms contained in the trivalent chromium compound is A / (A+B+C).

10. Enclosed container and A plurality of lead wires for a non-aqueous electrolyte battery according to any one of claims 1 to 9, arranged to extend from the inside to the outside of the above-mentioned sealed container, Non-aqueous electrolyte and A non-aqueous electrolyte battery equipped with the following features.

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