Leads and Energy Storage Devices

Abstract

The lead wire comprises a lead conductor and a film that coats at least a portion of the surface of the lead conductor. This film contains a trivalent chromium compound and a first metal, wherein the ratio of the concentration of the first metal to the concentration of the trivalent chromium compound at the surface of the film is 0.01-4.0.

Description

[Technical Field]

[0001] The present disclosure relates to leads and power storage devices. [Background technology]

[0002] In power storage devices such as lithium-ion secondary batteries, the battery elements (positive electrode, negative electrode, and electrolyte) are generally housed in a container, with lead conductors extending from the inside to the outside of the container to extract current. The container and lead conductors are joined by thermal fusion with resin or the like, thereby sealing the battery elements.

[0003] However, over time, the bonding strength gradually weakens, causing the lead conductor to separate from the container. This occurs because moisture permeates through the bond over time, reacting with the electrolyte stored inside the container and generating hydrofluoric acid, which corrodes the lead conductor. Therefore, the lead conductor must have corrosion resistance and adhesive properties. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-156365 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-184494 Summary of the Invention

[0005] A lead wire according to one aspect of the present disclosure includes: A lead wire including a lead conductor and a coating covering at least a portion of a surface of the lead conductor, the coating includes a trivalent chromium compound and a first metal; The ratio of the concentration of the first metal to the concentration of the trivalent chromium compound on the surface of the coating is 0.01 or more and 4.0 or less.

[0006] A lead wire according to another embodiment of the present disclosure includes: A lead wire including a lead conductor and a coating covering at least a portion of a surface of the lead conductor, The coating is a trivalent chromium compound and and 1Contains hydroxides of elements that make up metals, the trivalent chromium compound includes chromium hydroxide, the ratio of the concentration of chromium hydroxide to the concentration of trivalent chromium compounds on the surface of the coating is 0.3 or more and 0.9 or less; The ratio of the concentration of the hydroxide of the element that constitutes the first metal to the concentration of the trivalent chromium compound on the surface of the coating is 0.01 or more and 1.0 or less.

[0007] A lead wire according to another embodiment of the present disclosure includes: A lead wire including a lead conductor and a coating covering at least a portion of a surface of the lead conductor, the coating includes a trivalent chromium compound, a first metal, and a calcium compound; The ratio of the concentration of calcium to the concentration of trivalent chromium compounds on the surface of the coating is 0.01 or more and 1.0 or less.

[0008] A power storage device according to the present disclosure includes the lead wire according to the present disclosure. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a partial cross-sectional view of the lead wire according to the first to third embodiments. [Figure 2] FIG. 2 is an overall cross-sectional view of the lead wire according to the first to third embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Problem to be solved by this disclosure] There has been a demand for improving the corrosion resistance and adhesiveness of lead conductors. To solve these problems, for example, Japanese Patent Laid-Open Publication No. 2015-156365 (Patent Document 1) discloses a lead wire including a coating containing trivalent chromium that coats the surface of the lead conductor and a thermal fusion layer that coats the surface of the coating. Furthermore, Japanese Patent Laid-Open Publication No. 2016-184494 (Patent Document 2) discloses a lead wire including two nickel plating layers that coat the surface of the lead conductor and a trivalent chromium film that coats the nickel plating layers. However, the corrosion resistance and adhesiveness were not necessarily sufficient.

[0011] The present inventors have considered it desirable to improve corrosion resistance and adhesion compared to conventional methods, and have completed the present disclosure.

[0012] Therefore, an object of the present disclosure is to provide a lead wire having high corrosion resistance and adhesiveness.

[0013] [Effects of this disclosure] According to the present disclosure, it is possible to provide a lead wire having high corrosion resistance and adhesiveness. [Description of the embodiments of the present disclosure] First, the contents of one aspect of the present disclosure will be listed and described.

[0014] [1] A lead wire according to one embodiment of the present disclosure includes: A lead wire including a lead conductor and a coating covering at least a portion of a surface of the lead conductor, the coating includes a trivalent chromium compound and a first metal; The ratio of the concentration of the first metal to the concentration of the trivalent chromium compound on the surface of the coating is 0.01 or more and 4.0 or less.

[0015] The lead wire has improved corrosion resistance due to the coating containing a trivalent chromium compound. Furthermore, when the lead wire includes a thermally adhesive layer, the coating contains a first metal, improving adhesion between the coating and the thermally adhesive layer. Furthermore, the ratio of the concentration of the first metal to the concentration of the trivalent chromium compound on the surface of the coating is 4.0 or less, improving corrosion resistance. Therefore, the lead wire has high corrosion resistance and adhesiveness.

[0016] [2] The ratio of the concentration of the first metal to the concentration of the trivalent chromium compound on the surface of the coating is preferably 0.1 to 4.0, which more reliably provides a lead wire with high corrosion resistance and adhesiveness.

[0017] [3] A lead wire according to another embodiment of the present disclosure includes: A lead wire including a lead conductor and a coating covering at least a portion of a surface of the lead conductor, The coating is a trivalent chromium compound and and 1Contains hydroxides of elements that make up metals, the trivalent chromium compound includes chromium hydroxide, the ratio of the concentration of chromium hydroxide to the concentration of trivalent chromium compounds on the surface of the coating is 0.3 or more and 0.9 or less; The ratio of the concentration of the hydroxide of the element that constitutes the first metal to the concentration of the trivalent chromium compound on the surface of the coating is 0.01 or more and 1.0 or less.

[0018] The lead wire has improved corrosion resistance due to the coating containing a trivalent chromium compound. Furthermore, when the lead wire includes a thermal seal layer, the coating contains chromium hydroxide and hydroxide of the elements constituting the first metal, forming hydrogen bonds and improving adhesion between the coating and the thermal seal layer. Furthermore, when the lead wire includes a thermal seal layer, the ratio of the concentration of chromium hydroxide to the concentration of trivalent chromium compound on the surface of the coating is 0.3 to 0.9, and the ratio of the concentration of hydroxide of the elements constituting the first metal to the concentration of trivalent chromium compound on the surface of the coating is 0.01 to 1.0, improving adhesion between the coating and the thermal seal layer. Therefore, the lead wire has high corrosion resistance and adhesiveness.

[0019] [4] A lead wire according to another embodiment of the present disclosure includes: A lead wire including a lead conductor and a coating covering at least a portion of a surface of the lead conductor, the coating includes a trivalent chromium compound, a first metal, and a calcium compound; The ratio of the concentration of calcium to the concentration of trivalent chromium compounds on the surface of the coating is 0.01 or more and 1.0 or less.

[0020] The lead wire has improved corrosion resistance due to the coating containing a trivalent chromium compound. Furthermore, when the lead wire includes a thermal seal layer, the coating contains a first metal, improving adhesion between the coating and the thermal seal layer. Furthermore, the inclusion of a calcium compound improves stability against decomposition products of electrolyte components in the power storage device, improving corrosion resistance. Furthermore, when the lead wire includes a thermal seal layer, the ratio of the calcium concentration to the trivalent chromium compound concentration on the surface of the coating is 0.01 or more and 1.0 or less, improving adhesion between the coating and the thermal seal layer. Therefore, the lead wire has high corrosion resistance and adhesiveness.

[0021] [5] The calcium compound preferably contains at least one selected from the group consisting of calcium hydroxide, calcium oxide, calcium sulfate, and calcium carbonate. This ensures that the lead wire has high corrosion resistance and adhesiveness.

[0022] [6] The first metal is the metal with the highest content in a first region surrounded by the surface of the coating and an imaginary plane positioned 500 nm away from the surface of the coating and parallel to the surface of the coating.

[0023] [7] The first metal is preferably at least one selected from the group consisting of nickel, aluminum, and copper.

[0024] [8] The coating preferably further contains metallic chromium, which more reliably provides a lead wire with high corrosion resistance and adhesiveness.

[0025] [9] The chromium content of the coating is 0.1 mg / m 2 More than 20mg / m 2 By specifying it in this way, it is possible to more reliably obtain a lead wire having high corrosion resistance and adhesiveness.

[0026]

[10] Preferably, the lead wire further includes a heat-sealing layer that covers at least a portion of the coating.

[0027]

[11] The heat-sealing layer is preferably made of a maleic anhydride-modified polyolefin resin, which ensures that the lead wire has high corrosion resistance and adhesiveness.

[0028]

[12] The thickness of the coating is preferably 1 nm or more and 50 nm or less. By specifying it in this way, the lead wire can be more reliably provided with high corrosion resistance and adhesiveness.

[0029]

[13] The coating further comprises a fluorine compound; The fluorine concentration on the surface of the coating is preferably 0.1 atomic % or more and 5.0 atomic % or less, which more reliably results in a lead wire with high corrosion resistance and adhesiveness.

[0030]

[14] The coating preferably does not contain hexavalent chromium compounds, because hexavalent chromium compounds are environmentally hazardous substances.

[0031]

[15] The lead conductor may be nickel, nickel-plated metal, or nickel-phosphorus alloy-plated metal.

[0032]

[16] The lead conductor may be aluminum or an aluminum alloy.

[17] The lead conductor may be copper or a copper alloy.

[0033]

[18] The power storage device of the present disclosure includes the lead wire according to any one of [1] to

[17] . The power storage device having such a configuration has excellent high corrosion resistance and adhesiveness.

[0034] [Details of the embodiments of the present disclosure] Hereinafter, one embodiment of the present disclosure (hereinafter referred to as "the present embodiment") will be described. However, the present embodiment is not limited thereto. In this specification, when an element symbol or element name is described, it may mean a substance consisting of only that element, or it may mean a constituent element in a compound.

[0035] First Embodiment The lead wire of this embodiment will be described with reference to Figures 1 and 2. The lead wire of this embodiment includes a lead conductor 1 and a coating 2 that covers at least a portion of the surface of the lead conductor 1. The coating 2 contains a trivalent chromium compound and a first metal, and the ratio of the concentration of the first metal to the concentration of the trivalent chromium compound on surface A of the coating is 0.01 or more and 4.0 or less.

[0036] <Lead conductor> The lead conductor is a conductive member, and is a member that electrically connects, for example, an electrode housed in a container of a power storage device to an external member. The lead conductor is formed from a highly conductive material and includes a first metal. The first metal is any metal contained in the material that constitutes the lead conductor, and is preferably at least one selected from the group consisting of nickel (Ni), aluminum (Al), and copper (Cu).

[0037] Examples of highly conductive materials that make up the lead conductor include a first metal, a plated metal, an alloy, etc. Examples of plated metals include nickel-plated metals and nickel-phosphorus alloy-plated metals, and examples of alloys include aluminum alloys and copper alloys.

[0038] Also, referring to Figure 1, the first metal is the metal with the highest content in a first region C surrounded by a surface A of the coating and an imaginary plane B located 500 nm away from and parallel to the surface A of the coating.

[0039] The first metal can be confirmed by the following method: A cross section of a coating obtained using a focused ion beam device (FIB device), a cross-section polisher device (CP device), or the like is observed at 20,000x magnification with a scanning transmission electron microscope (SEM).

[0040] For the above observation field, elemental quantitative analysis is performed on the first region using energy dispersive X-ray spectrometry (hereinafter sometimes referred to as "EDX") attached to the SEM, and the metal element occupying the largest area is identified as the first metal.

[0041] The shape of the lead conductor is not particularly limited, but a flat plate shape with a thickness of 50 μm to 1000 μm, a width of 1 mm to 200 mm, and a length of 5 mm to 200 mm is preferably used.

[0042] <Coating> The coating covers at least a portion of the surface of the lead conductor. The coating is preferably provided on the entire surface of the lead conductor, but may also cover at least a portion of the surface of the lead conductor. In this embodiment, the "surface of the coating" refers to the surface opposite to the side that contacts the lead conductor, and this also applies to the following second and third embodiments.

[0043] (chromium) The coating contains a trivalent chromium (Cr) compound. The inclusion of the trivalent chromium compound in the coating improves the corrosion resistance of the coating. The trivalent chromium compound is a compound containing trivalent chromium, and examples thereof include chromium hydroxide, chromium chloride, chromium sulfate, chromium acetate, and chromium nitrate.

[0044] The coating may further contain metallic chromium, which improves adhesion between the lead conductor and the coating and provides high corrosion resistance.

[0045] The chromium content of the coating is, for example, 0.1 mg / m 2 More than 20mg / m 2 Here, the chromium contained in the film refers to the total amount of trivalent chromium compounds and metallic chromium converted into chromium. 2 If the chromium content in the coating is less than 20 mg / m, the coating will not be formed uniformly and corrosion resistance will tend to decrease. 2 If the content of chromium in the film is more than 100%, cracks tend to form in the film, and the corrosion resistance tends to decrease. Content is 1 mg / m 2 More than 15mg / m 2 Preferably less than 3 mg / m 2 More than 10mg / m 2 It is more preferable that it is less than 10 ...

[0046] The chromium content of the coating can be measured using inductively coupled plasma-mass spectrometry (hereinafter sometimes referred to as "ICP-MS"). The chromium content of the coating can be determined, for example, by cutting the lead conductor covered with the coating, immersing it in a hydrochloric acid solution to dissolve the lead conductor, and measuring the chromium concentration in the resulting solution using an inductively coupled plasma mass spectrometer (ICP-MS7700x, manufactured by Agilent Technologies).

[0047] The presence or absence of metallic chromium in the coating can be confirmed by measuring X-ray absorption spectra using a fluorescence yield method. For example, a synchrotron radiation facility (BL16 at the Saga Prefectural Kyushu Synchrotron Light Research Center (SAGA-LS)) can be used as the equipment for measuring X-ray absorption spectra. X-rays are irradiated onto the outermost surface of the coating using this equipment, and an X-ray absorption spectrum is obtained. The X-ray energy value on the horizontal axis of the obtained X-ray absorption spectrum is calibrated using metallic chromium, and then normalization and background processing are performed using software (e.g., REX2000 manufactured by Rigaku Corporation). The ratio of the X-ray absorption at 5990 eV to the X-ray absorption at 6007 eV is then calculated, and if this ratio is 0.1 or greater, it can be assumed that metallic chromium is present in the coating. (first metal) The coating contains a first metal. When the lead wire of this embodiment includes a thermal adhesive layer described below, the coating containing the first metal improves the adhesion between the coating and the thermal adhesive layer.

[0048] (Ratio of concentration of primary metal to concentration of trivalent chromium compounds) The ratio of the concentration of the first metal to the concentration of the trivalent chromium compound on the surface of the coating is 0.01 or more and 4.0 or less. If the ratio of the concentration of the first metal to the concentration of the trivalent chromium compound on the surface of the coating exceeds 4.0, the coating tends to be formed non-uniformly and have reduced corrosion resistance. The ratio of the concentration of the first metal to the concentration of the trivalent chromium compound on the surface of the coating is preferably 3.0 or less, more preferably 2.0 or less, and even more preferably 1.5 or less. Furthermore, the ratio of the concentration of the first metal to the concentration of the trivalent chromium compound on the surface of the coating may be, for example, 0.1 or more, 0.3 or more, or 0.5 or more.

[0049] The concentration of the trivalent chromium compound and the concentration of the first metal on the surface of the coating can be measured using X-ray Photoelectron Spectroscopy (hereinafter sometimes referred to as "XPS"). The measurement conditions for XPS are, for example, as follows. Surface The ratio of the concentration of the first metal to the concentration of the trivalent chromium compound in the above can be calculated by curve fitting the spectrum obtained under the following measurement conditions and determining the ratio of the peak areas. [XPS measurement conditions] X-ray source: Al-Kα X-ray source output: 15kV Photoelectron take-off angle: 45° Analysis area: 100 μm Φ Furthermore, the surface of the coating may have defects. Such defects may occur, for example, when the coating is formed on the surface of the lead conductor. Even if the surface of the coating has defects, the coating of this embodiment provides sufficient corrosion resistance and adhesiveness.

[0050] (Fluorine compounds) The coating may contain a fluorine (F) compound, which improves stability against decomposition products of the electrolyte components in the power storage device and provides a high level of corrosion resistance.

[0051] The fluorine concentration of the fluorine compound on the surface of the coating is preferably 0.1 atomic % or more and 5.0 atomic % or less, and more preferably 0.3 atomic % or more and 4.5 atomic % or less. If the fluorine concentration of the fluorine compound on the surface of the coating is less than 0.1 atomic %, corrosion resistance tends to decrease. If the fluorine concentration of the fluorine compound on the surface of the coating is more than 5.0 atomic %, adhesion between the lead conductor and the coating tends to decrease.

[0052] The fluorine concentration on the surface of the coating can be measured using XPS. The XPS measurement conditions are, for example, as follows. [XPS measurement conditions] X-ray source: Al-Kα X-ray source output: 15kV Photoelectron take-off angle: 45° Analysis area: 100 μm Φ (film thickness) The thickness of the coating is preferably 1 nm or more and 50 nm or less, and more preferably 3 nm or more and 20 nm or less. If the thickness of the coating is less than 1 nm, the coating will not be formed uniformly and corrosion resistance will tend to decrease. If the thickness of the coating is more than 50 nm, cracks will easily form in the coating and the coating density will tend to decrease, which will tend to decrease corrosion resistance.

[0053] The thickness of the coating can be measured in terms of SiO2. The thickness of the coating is defined as the sputtering depth in terms of SiO2 at which the composition ratio of chromium element is half of its maximum value, for example, by performing depth direction analysis by XPS under the following conditions: [XPS analysis conditions] X-ray source: Al-Kα X-ray source output: 15kV Photoelectron take-off angle: 45° Analysis area: 100 μm Φ (others) Other components contained in the coating include carbon, nitrogen, oxygen, sodium, phosphorus, sulfur, chlorine, potassium, and the like.

[0054] From the viewpoint of environmental protection in recent years, it is preferable that the coating does not contain hexavalent chromium compounds. Examples of hexavalent chromium compounds include dichromates and chromates. "Not containing hexavalent chromium compounds" means that the coating preferably does not contain any hexavalent chromium compounds at all, but it may also be that the amount of hexavalent chromium in the hexavalent chromium compounds is below the detection limit. The absence of hexavalent chromium compounds can be confirmed according to JIS H 8625.

[0055] <Thermal adhesive layer> The lead wire of this embodiment may further include a heat-sealing layer. The heat-sealing layer need only cover at least a part of the coating, and does not necessarily have to be provided on the entire coating.

[0056] The heat-sealing layer can be made of any resin that melts when heated (250°C to 300°C) during heat fusion, and examples thereof include polyolefin resins, acid-modified styrene elastomers, etc. Examples of polyolefin resins include polyethylene, polypropylene, ionomer resins, acid-modified polyolefins, etc. Acid-modified polyolefins that have been modified with maleic acid, acrylic acid, methacrylic acid, maleic anhydride, etc. and have adhesive functional groups are preferred, and they have excellent adhesion to metals. Sexual A superior maleic anhydride modified polyolefin resin is more preferred.

[0057] In addition to these resins, the heat-sealing layer can contain various additives such as flame retardants, UV absorbers, light stabilizers, heat stabilizers, lubricants, and colorants. These resin materials and additives are mixed using a known mixer such as an open roll, pressure kneader, single-screw mixer, or twin-screw mixer, and then extrusion molding is performed to produce a film-like heat-sealing layer. The thickness of the heat-sealing layer depends on the thickness of the lead conductor 1, but is preferably 30 μm to 200 μm.

[0058] The heat-sealing layer can also be used after crosslinking by irradiation with ionizing radiation such as accelerated electron beams or gamma rays. Crosslinking can increase heat resistance and prevent a decrease in adhesive strength when the temperature rises during use. The entire heat-sealing layer can be crosslinked, or the heat-sealing layer can have a multi-layer structure in which a non-crosslinked layer and a crosslinked layer are laminated.

[0059] <Peel strength> In the lead wire according to this embodiment, the adhesive strength between the lead conductor and the thermal adhesive layer can be evaluated by measuring the peel strength using the following method. Peel strength can be measured, for example, by cutting one of the lead conductor and the thermal adhesive layer of the lead wire, bending it 180°, and placing it in a tensile tester (EX-SX manufactured by Shimadzu Corporation). The cut portion is then pulled at a pulling speed of 50 mm / min. The higher the peel strength value, the better the adhesive strength between the lead conductor and the thermal adhesive layer, and the better the corrosion resistance.

[0060] Second Embodiment 1 and 2, the lead wire of this embodiment includes a lead conductor 1 and a coating 2 that covers at least a portion of the surface of the lead conductor 1. The coating 2 contains a trivalent chromium compound and a hydroxide of an element that constitutes a first metal, and the trivalent chromium compound contains chromium hydroxide. The ratio of the concentration of the chromium hydroxide to the concentration of the trivalent chromium compound on surface A of the coating is 0.3 to 0.9, and the ratio of the concentration of the hydroxide of the element that constitutes the first metal to the concentration of the trivalent chromium compound on surface A of the coating is 0.01 to 1.0. The lead wire of this embodiment will be described below, but explanations that overlap with those of embodiment 1 will be omitted.

[0061] (hydroxide) The coating contains hydroxides, specifically, hydroxides of elements constituting the first metal and chromium hydroxide. When the lead wire of this embodiment includes a thermally sealed layer, the coating contains hydroxides of elements constituting the first metal and chromium hydroxide, and hydroxyl groups formed on the surface of the metal containing the first metal and hydroxyl groups of the hydroxide form hydrogen bonds, improving the adhesion between the coating and the thermally sealed layer. Examples of hydroxides of elements constituting the first metal include nickel(II) hydroxide, aluminum hydroxide, and copper(II) hydroxide.

[0062] (ratio of chromium hydroxide concentration to trivalent chromium compound concentration) The ratio of the concentration of chromium hydroxide to the concentration of trivalent chromium compounds on the surface of the coating is 0.3 to 0.9. When the lead wire of this embodiment includes a thermally adhesive layer, the ratio of the concentration of chromium hydroxide to the concentration of trivalent chromium compounds on the surface of the coating is 0.3 to 0.9, thereby improving the adhesion between the coating and the thermally adhesive layer. The ratio of the concentration of chromium hydroxide to the concentration of trivalent chromium compounds on the surface of the coating is preferably 0.35 to 0.8, and more preferably 0.4 to 0.7.

[0063] (Ratio of the concentration of hydroxides of elements constituting the first metal to the concentration of trivalent chromium compounds) Furthermore, the ratio of the concentration of the hydroxide of the element constituting the first metal to the concentration of the trivalent chromium compound on the surface of the coating is 0.01 or more and 1.0 or less. When the lead wire of this embodiment includes a thermal seal layer, the ratio of the concentration of the hydroxide of the element constituting the first metal to the concentration of the trivalent chromium compound on the surface of the coating is 0.01 or more and 1.0 or less, thereby improving the adhesion between the coating and the thermal seal layer. The elements that make up The ratio of the hydroxide concentrations is preferably 0.05 or more and 0.8 or less, and more preferably 0.1 or more and 0.6 or less.

[0064] The concentrations of trivalent chromium compounds, chromium hydroxide, and hydroxides of elements constituting the first metal on the surface of the coating can be measured using XPS. The XPS measurement conditions are, for example, as follows. The ratio of the concentration of chromium hydroxide to the concentration of trivalent chromium compounds on the surface of the coating and the ratio of the concentration of hydroxides of elements constituting the first metal to the concentration of trivalent chromium compounds on the surface of the coating can be calculated by curve fitting the spectra obtained under the measurement conditions below and determining the ratio of the peak areas. [XPS measurement conditions] X-ray source: Al-Kα X-ray source output: 15kV Photoelectron take-off angle: 45° Analysis area: 100 μm Φ Third Embodiment 1 and 2, the lead wire of this embodiment includes a lead conductor 1 and a coating 2 that covers at least a portion of the surface of the lead conductor 1. The coating 2 includes a trivalent chromium compound, a first metal, and a calcium compound. The ratio of the concentration of calcium to the concentration of the trivalent chromium compound on surface A of the coating is 0.01 or more and 1.0 or less. The lead wire of this embodiment will be described below, but descriptions that overlap with those of embodiments 1 and 2 will be omitted.

[0065] (Calcium compounds) The coating contains a calcium (Ca) compound. The inclusion of the calcium compound in the coating improves stability against decomposition products of the electrolyte components in the power storage device, resulting in excellent corrosion resistance. The calcium compound is not particularly limited, and examples thereof include calcium hydroxide, calcium oxide, calcium sulfate, and calcium carbonate.

[0066] The ratio of the calcium concentration to the trivalent chromium compound concentration on the surface of the coating is 0.01 or more and 1.0 or less. When the lead wire of this embodiment includes a thermally adhesive layer, the ratio of the calcium concentration to the trivalent chromium compound concentration on the surface of the coating is 0.01 or more and 1.0 or less, thereby improving the adhesion between the coating and the thermally adhesive layer. The ratio of the calcium concentration to the trivalent chromium compound concentration on the surface of the coating is preferably 0.03 or more and 0.7 or less, and more preferably 0.05 or more and 0.4 or less.

[0067] The concentrations of trivalent chromium compounds and calcium on the surface of the coating can be measured using XPS. The XPS measurement conditions are, for example, as follows. The ratio of the calcium concentration to the trivalent chromium compound concentration on the surface of the coating can be calculated by curve fitting the spectrum obtained under the measurement conditions below and determining the ratio of the peak areas. [XPS measurement conditions] X-ray source: Al-Kα X-ray source output: 15kV Photoelectron take-off angle: 45° Analysis area: 100 μm Φ ≪Applications≫ The lead wires of Embodiments 1 to 3 are suitable for use in power storage devices, such as non-aqueous electrolyte batteries and electric double layer capacitors that use non-aqueous electrolyte solutions, and aqueous electrolyte batteries in which the main solvent of the electrolyte solution is water. [Example]

[0068] The present disclosure will be described in detail below with reference to examples, but the present disclosure is not limited to these examples.

[0069] <Making lead wires> <Sample 1> (Making lead conductors) The lead conductor was made of an oxygen-free copper plate (C1020) with a length of 100 mm, a width of 45 mm, and a thickness of 0.2 mm. As a pretreatment, the substrate was immersed in a sodium hydroxide solution (40 g / L) at 25°C, and a current density of 1.0 A / dm 2 After the degreasing, the substrate was washed with running water.

[0070] Next, the washed substrate was subjected to acid activation by immersing the substrate in an aqueous sulfuric acid solution (10% by mass) at 25° C. for 30 seconds, and then the substrate after acid activation was washed with running water.

[0071] Next, nickel amidosulfate tetrahydrate (350 g / L), nickel chloride hexahydrate (30 g / L), and boric acid (30 g / L) were mixed to obtain a nickel plating solution. The acid-activated substrate was immersed in the nickel plating solution at 50°C, and a current density of 5.0 A / dm 2 The plating was carried out for 120 seconds. After plating, the base material was washed with running water to obtain a lead conductor made of nickel-plated copper (nickel-plated metal).

[0072] (film formation) 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 / dm 2 After cathodic electrolysis, the lead conductor was washed with running water to obtain a lead conductor having a coating film as shown in Table 1.

[0073] (Formation of heat-sealed layer) Both sides of the lead conductor on which the coating was formed were covered with a 50 μm-thick maleic anhydride-modified polypropylene film, and the film was pressed and bonded at 260° C. for 30 seconds. Thus, the lead wire of Sample 1 was produced.

[0074] <Samples 2-5, A-C> For samples 2 to 5 and A to C, the same lead conductor as that of sample 1 was used. For sample 2, the cathodic electrolysis time was set to 40 seconds, except for sample 3, the cathodic electrolysis time was set to 5 seconds, except for sample 4, the concentration of chromium chloride hexahydrate was set to 10 g / L, and for sample 5, the cathodic electrolysis time was set to 60 seconds and the concentration of chromium chloride hexahydrate was set to 10 g / L. For sample A, the current density was set to 1 A / dm 2 A lead conductor with a coating formed thereon was obtained in the same manner as in Sample 1, except that in Sample B, the concentration of chromium chloride hexahydrate was 1.0 g / L, and in Sample C, the time of cathodic electrolysis was 90 seconds and the concentration of chromium chloride hexahydrate was 10 g / L. In addition, a thermally fused layer was formed in the same manner as in Sample 1, and lead wires for each sample were produced.

[0075] <Sample 6> (Making lead conductors) The lead conductor was made of an aluminum plate (A1050) with a length of 100 mm, a width of 45 mm, and a thickness of 0.2 mm. As a pretreatment, the substrate was immersed in a sodium hydroxide aqueous solution (40 g / L) at 25°C, and a current density of 1.0 A / dm 2 After degreasing, the substrate was washed with running water to obtain a lead conductor.

[0076] (film formation) 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 / dm 2 After cathodic electrolysis, the lead conductor was washed with running water to obtain a lead conductor having a coating film as shown in Table 1.

[0077] (Formation of heat-sealed layer) A thermally adhesive layer was formed in the same manner as in Sample 1, to prepare a lead wire for Sample 6.

[0078] <Sample 7> For sample 7, a lead wire was prepared in the same manner as for sample 6, except that potassium fluoride (5.0 g / L) was further mixed into the surface treatment solution for sample 6.

[0079] <Sample 8> The lead conductor was made of an oxygen-free copper plate (C1020) with a length of 100 mm, a width of 45 mm, and a thickness of 0.2 mm. As a pretreatment, the substrate was immersed in a sodium hydroxide solution (40 g / L) at 25°C, and a current density of 1.0 A / dm 2 Cathodic electrolytic degreasing was performed. The degreased substrate was washed with running water. Next, the washed substrate was immersed in a sulfuric acid aqueous solution (10 mass %) at 25°C for 30 seconds to perform acid activation. The acid-activated substrate was then washed with running water to obtain a lead conductor. The formation of the coating and the thermal fusion layer was performed in the same manner as in Sample 1.

[0080] <Sample 9> (Making lead conductors) A lead conductor made of nickel-plated copper (nickel-plated metal) was prepared in the same manner as in Sample 1.

[0081] (film formation) 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 / dm 2 After the cathodic electrolysis, the lead conductor was washed with running water and dried in a thermostatic chamber at 100°C for 180 seconds to obtain a lead conductor having a coating film as shown in Table 2.

[0082] (Formation of heat-sealed layer) A thermally adhesive layer was formed in the same manner as in Sample 1, to prepare a lead wire for Sample 9.

[0083] <Samples 10-13, D-E> For samples 10 to 13 and D to E, the same lead conductors as in sample 9 were used. For sample 10, the cathodic electrolysis time was set to 5 seconds; for sample 11, the concentration of chromium chloride hexahydrate was set to 10 g / L; for sample 12, the drying time after cathodic electrolysis was set to 30 seconds; for sample 13, the drying time after cathodic electrolysis was set to 3600 seconds; and for sample D, the drying time was set to 3600 seconds in a thermostatic chamber at 250°C after cathodic electrolysis. , trial A lead conductor with a coating was obtained in the same manner as in Sample 9. For sample E, a lead conductor was obtained in which a coating was formed using a method that was partially different from that used for sample 9. Further, a thermal adhesive layer was formed in the same manner as in Sample 1, and lead wires were prepared for each sample.

[0084] <Sample 14> (Making lead conductors) A lead conductor made of nickel-plated copper (nickel-plated metal) was prepared in the same manner as in Sample 1.

[0085] (film formation) Chromium chloride hexahydrate (5.0 g / L), potassium formate (170 g / L), and calcium chloride (0.5 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 / dm 2 After the cathodic electrolysis, the lead conductor was washed with running water and dried in a thermostatic chamber at 100°C for 180 seconds to obtain a lead conductor having a coating film as shown in Table 3.

[0086] (Formation of heat-sealed layer) A thermally adhesive layer was formed in the same manner as in Sample 1, to prepare a lead wire for Sample 14.

[0087] <Sample 15, F> For Samples 15 and F, the same lead conductor as in Sample 14 was used. A lead conductor with a coating formed thereon was obtained in the same manner as in Sample 14, except that the calcium chloride concentration in Sample 15 was 3.0 g / L, and in Sample F, the calcium chloride concentration was 5.0 g / L. In addition, a thermally adhesive layer was formed in the same manner as in Sample 1, and lead wires for each sample were produced.

[0088] The lead wires of Samples 1 to 15 correspond to Examples, and the lead wires of Samples A to F correspond to Comparative Examples.

[0089] [Table 1]

[0090] [Table 2]

[0091] [Table 3]

[0092] <Sample Observation> <First metal> For each sample, the cross section of the coating obtained using a cross-section polisher (CP) was observed at 20,000x magnification using an SEM, and elemental mapping was performed on multiple first regions using an EDX attached to the SEM. In the elemental mapping, the element with the highest content ratio was designated as the first metal. The results are shown in the "First Metal" column in Tables 1 to 3. In the tables, Ni stands for "nickel," Al stands for "aluminum," and Cu stands for "copper."

[0093] <Calculation of chromium content> The portion of the lead wire of each sample where the heat-sealing layer was not bonded was cut into a width of 10 mm and immersed in dilute hydrochloric acid (3 mol / L) at 50°C for 60 minutes. The amount of chromium in the resulting solution was measured using an inductively coupled plasma mass spectrometer (ICP-MS7700x, manufactured by Agilent Technologies). From the results, the chromium content (mg / m) in the coating was calculated. 2 The results are shown in Tables 1 to 3 as "Cr content (mg / m 2 ) column.

[0094] <Chromium metal> X-rays were irradiated onto the outermost surface of each sample's coating at a synchrotron radiation facility (Saga Prefectural Kyushu Synchrotron Light Research Center, BL16), and X-ray absorption spectra were obtained. The X-ray energy values ​​on the horizontal axis of the obtained X-ray absorption spectra were calibrated using metallic chromium, and then normalization and background processing were performed using software (Rigaku Corporation, REX2000). The ratio of the X-ray absorption at 5990 eV to the X-ray absorption at 6007 eV was calculated to confirm the presence or absence of metallic chromium in the coating of each sample. The results are shown in the "Metallic Cr" column in Tables 1 to 3. A ratio of 0.1 or greater was recorded as "present," and a ratio of less than 0.1 was recorded as "absent."

[0095] <Coating thickness> An X-ray photoelectron spectrometer (Quantera SXM, manufactured by ULVAC-PHI) was used to perform depth profile analysis of the film of each sample under the following conditions, and the SiO2-equivalent depth of the chromium element associated with the peaks at 573 eV to 578 eV was calculated. The SiO2 etching rate measured with the X-ray photoelectron spectrometer was 1.0 nm / min. The results are shown in the "Thickness (nm)" column of Tables 1 to 3. [XPS measurement conditions] X-ray source: Al-Kα X-ray source output: 15kV Photoelectron take-off angle: 45° Analysis area: 100 μm Φ <Ratio of first metal concentration> Using an X-ray photoelectron spectrometer (Quantera SXM manufactured by ULVAC-PHI, Inc.), the concentrations of trivalent chromium compounds and the first metal on the surfaces of the coatings of Samples 1 to 8 and A to C were measured under the same conditions as those in the [XPS measurement conditions] section of <Coating thickness> above, and the ratio of the concentration of the first metal to the concentration of the trivalent chromium compounds on the surfaces of the coatings was calculated. The results are shown in the "First metal concentration ratio" column in Table 1. The fluorine concentration in the coating of Sample 7 was measured under the same conditions, and was found to be 4.0 atomic %.

[0096] <Concentration ratio of chromium hydroxide, concentration ratio of hydroxides of elements that make up the first metal> Using an X-ray photoelectron spectrometer (Quantera SXM, manufactured by ULVAC-PHI, Inc.) under the same conditions as those in the "XPS Measurement Conditions" section above under "Coating Thickness," the concentrations of trivalent chromium compounds, chromium hydroxide, and hydroxides of elements constituting the first metal were measured on the surfaces of the coatings of Samples 9-13 and D-E, and the ratios of the chromium hydroxide concentration to the trivalent chromium compound concentration on the surfaces of the coatings and the ratios of the hydroxides of elements constituting the first metal concentration to the trivalent chromium compound concentration on the surfaces of the coatings were calculated. The results are shown in the "Cr hydroxide concentration ratio" and "Hydroxide concentration ratio of elements constituting the first metal" columns in Table 2.

[0097] <Calcium concentration ratio> Using an X-ray photoelectron spectrometer (Quantera SXM, manufactured by ULVAC-PHI, Inc.), the concentrations of trivalent chromium compounds and calcium on the surface of the coatings of samples 14-15 and E-F were measured under the same conditions as those in [XPS measurement conditions] under <Coating thickness> above, and the ratio of the calcium concentration to the trivalent chromium compound concentration on the surface of the coating was calculated. The results are shown in the "Ca concentration ratio" column in Table 3.

[0098] <Evaluation Test> <Peel test> The peel strength of Samples 1 to 15 and Samples A to F was measured by the following method. In this test, the "initial peel strength" was measured immediately after production, and the "4-week peel strength" was measured 4 weeks after production.

[0099] (Initial peel strength) One of the lead conductors and the thermal adhesive layer of Samples 1 to 15 and A to F was cut and bent at 180°, and set in a tensile tester (Shimadzu EX-SX). The set cut portion was pulled at a pulling speed of 50 mm / min to measure the initial peel strength. The results are shown in Tables 1 to 3 under "Initial Peel Strength (N / cm 2 The initial peel strength is shown in the " 2 In the above cases, the lead wire can be evaluated as having high adhesiveness.

[0100] (4-week peel strength) A test solution was prepared by mixing ethylene carbonate, diethyl carbonate, and dimethyl carbonate in a volume ratio of 1:1:1, and dissolving lithium hexafluorophosphate (LiPF6) to a concentration of 1.0 mol / L. 15 and A~ F The test solution was adjusted to a moisture content of 1000 ppm, and the test solution was left in a thermostatic chamber at 80°C for 4 weeks. After that, the test was measured in the same manner as in "(Initial peel strength)" above. The results are shown in "Peel strength 4 weeks (N / cm 2 The test solution is generally used as an electrolyte for battery elements in power storage devices, and was prepared to evaluate the corrosion resistance of lead wires. 2 In the above cases, the lead wire can be evaluated as having high corrosion resistance.

[0101] <Consideration> Samples 1 to 8, in which the ratio of the concentration of the first metal to the concentration of the trivalent chromium compound on the surface of the coating was 0.01 or more and 4.0 or less, showed high values ​​for both the initial peel strength and the 4-week peel strength, which indicates that the lead wires of these samples have high corrosion resistance and adhesiveness.

[0102] On the other hand, samples A to C, in which the ratio of the concentration of the first metal to the concentration of the trivalent chromium compound on the surface of the coating was not within the range of 0.01 to 4.0, had high adhesion but reduced corrosion resistance.

[0103] Samples 9 to 13, in which the ratio of the concentration of chromium hydroxide to the concentration of trivalent chromium compounds on the surface of the coating was 0.3 to 0.9 and the ratio of the concentration of the hydroxide of the element constituting the first metal to the concentration of trivalent chromium compounds on the surface of the coating was 0.01 to 1.0, exhibited high initial peel strength and 4-week peel strength, demonstrating that the lead wires of these samples had high corrosion resistance and adhesiveness.

[0104] On the other hand, sample D, in which the ratio of the concentration of chromium hydroxide to the concentration of trivalent chromium compounds on the surface of the coating was 0.2, and sample E, in which the ratio of the concentration of hydroxides of the elements constituting the first metal to the concentration of trivalent chromium compounds on the surface of the coating was 1.2, had high adhesion but reduced corrosion resistance.

[0105] Samples 14 and 15, in which the ratio of calcium concentration to trivalent chromium compound concentration on the coating surface was 0.01 or more and 1.0 or less, showed high values ​​for both the initial peel strength and the 4-week peel strength, indicating that the lead wires of these samples had high corrosion resistance and adhesiveness.

[0106] On the other hand, sample E, which does not contain calcium, had high adhesion but poor corrosion resistance. Also, sample F, which had a ratio of calcium concentration to trivalent chromium compound concentration on the coating surface of 1.2, showed low initial peel strength and 4-week peel strength.

[0107] Although the embodiments and examples of the present disclosure have been described above, it is also planned from the beginning that the configurations of the above-described embodiments and examples may be appropriately combined.

[0108] The embodiments and examples disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims, not by the embodiments and examples described above, and is intended to include any modifications equivalent to the claims and within the scope thereof. [Explanation of symbols]

[0109] 1 Lead conductor, 2 Coating, A Coating surface, B Imaginary plane, C First region.

Claims

1. A lead wire including a lead conductor and a coating covering at least a portion of a surface of the lead conductor, the coating includes a trivalent chromium compound and a first metal; a ratio of the concentration of the first metal to the concentration of trivalent chromium compounds on the surface of the coating, measured by X-ray photoelectron spectroscopy under the following conditions, being 0.01 or more and 4.0 or less; The lead wire, wherein the first metal is at least one selected from the group consisting of nickel, aluminum, and copper. [X-ray photoelectron spectroscopy measurement conditions] X-ray source: Al-Kα X-ray source output: 15 kV Photoelectron take-off angle: 45° Analysis area: 100 μm diameter

2. 2. The lead wire according to claim 1, wherein a ratio of a concentration of the first metal to a concentration of the trivalent chromium compound on the surface of the coating is 0.1 or more and 4.0 or less.

3. A lead wire including a lead conductor and a coating covering at least a portion of a surface of the lead conductor, the coating contains a trivalent chromium compound and a hydroxide of an element constituting a first metal, the trivalent chromium compound includes chromium hydroxide, the ratio of the concentration of chromium hydroxide to the concentration of trivalent chromium compounds on the surface of the coating, measured by X-ray photoelectron spectroscopy under the following conditions, is 0.3 or more and 0.9 or less; A lead wire, wherein a ratio of a concentration of a hydroxide of an element constituting the first metal to a concentration of a trivalent chromium compound on the surface of the coating is 0.01 or more and 1.0 or less. [X-ray photoelectron spectroscopy measurement conditions] X-ray source: Al-Kα X-ray source output: 15 kV Photoelectron take-off angle: 45° Analysis area: 100 μm diameter

4. A lead wire including a lead conductor and a coating covering at least a portion of a surface of the lead conductor, the coating comprises a trivalent chromium compound, a first metal, and a calcium compound; a ratio of a calcium concentration to a trivalent chromium compound concentration on the surface of the coating, measured by X-ray photoelectron spectroscopy under the following conditions, of 0.01 or more and 1.0 or less; [X-ray photoelectron spectroscopy measurement conditions] X-ray source: Al-Kα X-ray source output: 15 kV Photoelectron take-off angle: 45° Analysis area: 100 μm diameter

5. The lead wire according to claim 4 , wherein the calcium compound includes at least one selected from the group consisting of calcium hydroxide, calcium oxide, calcium sulfate, and calcium carbonate.

6. 6. The lead wire according to claim 1, wherein the first metal is the metal with the highest content in a first region surrounded by the surface of the coating and an imaginary plane located 500 nm away from the surface of the coating and parallel to the surface of the coating.

7. The lead wire according to claim 3 , wherein the first metal is at least one selected from the group consisting of nickel, aluminum, and copper.

8. The lead wire according to claim 1 , wherein the coating further comprises metallic chromium.

9. The chromium content of the coating is 0.1 mg / m ２ 20mg / m or more ２ The lead wire according to any one of claims 1 to 8, wherein the lead wire has a length of less than 1 / 2 mm.

10. The lead wire according to claim 1 , further comprising a heat-sealing layer covering at least a portion of the coating.

11. The lead wire according to claim 10 , wherein the heat-sealing layer is made of a maleic anhydride-modified polyolefin resin.

12. The lead wire according to claim 1 , wherein the coating has a thickness of 1 nm or more and 50 nm or less.

13. The coating further comprises a fluorine compound, 13. The lead wire according to claim 1, wherein a fluorine concentration on the surface of the coating is 0.1 atomic % or more and 5.0 atomic % or less.

14. The lead wire according to claim 1 , wherein the coating does not contain a hexavalent chromium compound.

15. The lead wire according to any one of claims 1 to 14, wherein the lead conductor is made of nickel, nickel-plated metal, or nickel-phosphorus alloy-plated metal.

16. The lead wire according to claim 1 , wherein the lead conductor is made of aluminum or an aluminum alloy.

17. The lead wire according to claim 1 , wherein the lead conductor is copper or a copper alloy.

18. A power storage device comprising the lead wire according to any one of claims 1 to 17.

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