WO2017002421A1 - Lead conductor and power storage device - Google Patents

Abstract

This lead conductor is for use in a power storage device provided with a positive electrode, a negative electrode, an electrolyte solution, and a container for accommodating the positive electrode, the negative electrode, and the electrolyte solution. The lead conductor is configured from an aluminum alloy containing: 0.1-1.2 mass% of Si; and Mg in a range that is less than 1.5 mass% and that results in the mass ratio of Mg/Si being 0.8-2.7. The lead conductor has a tensile strength of 100-220 MPa and a conductivity of 50% IACS or more.

Description

Lead conductor and power storage device

The present invention relates to a lead conductor used in a power storage device such as a nonaqueous electrolyte battery, and a power storage device. In particular, the present invention relates to a lead conductor that is thin and thin and hardly breaks.

Lithium ion secondary batteries are used as power sources for portable electronic / electrical devices such as mobile phones such as smartphones and notebook personal computers, and small electronic / electrical devices (hereinafter sometimes referred to as portable devices). . A typical lithium-ion secondary battery for use as a power source for portable devices has a configuration in which a battery element is housed in a bag-like container and lead conductors are arranged from the inside to the outside of the container (Patent Document 1). 1 and 2).

The lead conductor is mainly made of a metal strip that transfers power between the battery and an external member. In the above-described power supply application for portable devices, pure aluminum is used for the positive lead conductor, and pure nickel or pure nickel-plated pure copper is used for the negative lead conductor.

The above-mentioned bag-shaped container is typically provided with a metal layer. In order to insulate the metal layer from the metal lead conductor, the two are joined via a resin layer. The container is sealed through this resin layer. A lead conductor with resin in which a resin layer is formed on a metal strip is also used.

JP 2014-0117175 A

It is desired that lead conductors used for power storage devices such as lithium ion secondary batteries are not easily broken even if they are thin and narrow.

Recently, the power consumption of portable devices is increasing due to the high specification of portable electronic / electrical devices and small electronic / electrical devices. For this reason, lithium ion secondary batteries and the like used for power supplies of portable devices are required to increase battery capacity (energy density) while being thin and small, and lead conductors are also thicker than before. It is desired to reduce the thickness and the width.

However, lead conductors made of pure metals such as pure aluminum and pure nickel and having a thin and narrow width, for example, a thickness of 0.1 mm or less and a width of 10 mm or less, are assembled in a manufacturing process or in portable devices. There is a risk of breaking.

In the manufacturing process, for example, the lead conductor may be bent into a predetermined shape and connected to a member such as a circuit board provided in portable devices. By bending the lead conductor, the portable device can be stored even when the casing of the portable device is thin or small. If the bending radius is reduced, such as right-angle bending or double folding, the storage capacity of the lead conductor can be further reduced. However, thin and narrow pure metal lead conductors have a small breaking load, so if they are bent with a small bending radius so that they can be stored in a thin housing, etc., they may break and fall during transport before assembly. There is a possibility of breaking even if an impact such as doing is applied.

Even after being assembled in mobile devices, if an impact is applied by dropping the mobile devices, etc., there is a possibility that the thin and thin pure metal lead conductor may break. If an impact such as dropping is applied in the bent state as described above, excessive bending that exceeds the allowable stress is applied to the bent part, and the thin and thin pure metal lead conductor may break. It is thought that there is also.

Furthermore, since the lead conductor provided in the power storage device is used for power transfer, it is also desired that the lead conductor is excellent in conductivity.

The present invention has been made in view of the above circumstances, and one of its purposes is to provide a lead conductor for a power storage device that is thin and thin and hardly breaks. Another object of the present invention is to provide a power storage device including a lead conductor that is thin and thin but hardly broken.

The lead conductor which concerns on 1 aspect of this invention is used for an electric power storage device provided with a positive electrode, a negative electrode, electrolyte solution, and the container which accommodates these.
This lead conductor contains 0.1 mass% or more and 1.2 mass% or less of Si, and Mg has a mass ratio of Mg / Si of 0.8 or more and 2.7 or less, and less than 1.5 mass%. It is comprised from the aluminum alloy contained in the range to satisfy | fill.
The tensile strength of this lead conductor is 100 MPa or more and 220 MPa or less.
The conductivity of the lead conductor is 50% IACS or more.

A power storage device according to an aspect of the present invention includes the above lead conductor.

The above lead conductors are not easily broken even if they are thin and narrow. In the above power storage device, the lead conductor is not easily broken.

It is a perspective view showing the outline of the nonaqueous electrolyte battery which is an example of the power storage device of an embodiment. FIG. 2 is a cross-sectional view of the nonaqueous electrolyte battery of the embodiment taken along the line (II)-(II) shown in FIG. It is explanatory drawing explaining the test method of a bending test. It is explanatory drawing explaining the test method of an impact test. It is a schematic block diagram which shows an example of the electrochemical measurement cell used for the measurement of a diffused resistance value. It is an equivalent circuit diagram used for calculation of a diffused resistance value. It is the schematic of the sample used for a peel strength test. In a peel strength test, it is explanatory drawing which shows the sample before peel strength measurement, and the state which measures peel strength.

DESCRIPTION OF SYMBOLS 1 Lead conductor 10 Nonaqueous electrolyte battery 11 Container 110 Metal layer 112 Inner resin layer 114 Outer resin layer 13 Separator 14 Positive electrode 15 Negative electrode 16, 17 Current collector 19 Lead wire 20 Lead conductor with resin 22 Coating resin layer 220 Adhesive layer 222 Surface Layer 300 Electrochemical measurement cell 302 Counter electrode 304 Electrolyte 310 Measuring device S Sample w Weight SS1, SS2 Simulated sample S1 Strip material S22 Resin layer S1l, S1s Split piece S22a, S22b Resin film la, sa Film piece

The inventors of the present invention say that a thin and thin lead conductor is not easily broken by bending or impact if it is made of a metal having a specific composition and the tensile strength and conductivity satisfy a specific range. Obtained knowledge. The present invention is based on the above findings.
First, the contents of the embodiment of the present invention will be listed and described.

(1) The lead conductor which concerns on 1 aspect of this invention is used for an electric power storage device provided with a positive electrode, a negative electrode, electrolyte solution, and the container which accommodates these.
This lead conductor contains 0.1 mass% or more and 1.2 mass% or less of Si, and Mg has a mass ratio of Mg / Si of 0.8 or more and 2.7 or less, and less than 1.5 mass%. It is comprised from the aluminum alloy contained in the range to satisfy.
The tensile strength of this lead conductor is 100 MPa or more and 220 MPa or less.
The conductivity of the lead conductor is 50% IACS or more.

The above lead conductor has a tensile strength that satisfies a specific range, is high in strength but is not too high (not too hard), and is excellent in toughness (for example, elongation at break). Such a lead conductor having high strength and high toughness is thin and thin, for example, with a resistance to bending or impact (for example, 0.1 mm or less) even if the thickness is 0.1 mm or less and the width is 10 mm or less. 2% proof stress), and it is difficult to break even if a predetermined bending is performed or an impact is applied. Preferably, the lead conductor is not easily broken even when subjected to an impact while being bent into a predetermined shape.

In addition, the above lead conductor has a specific conductivity and is excellent in conductivity. Here, the strength can be increased by increasing the content of the additive element in the constituent metal of the lead conductor, or by performing sufficient work hardening by plastic working at a high workability. However, excessive addition of additive elements, excessive strain introduction due to work hardening, and the like cause a decrease in conductivity. Said lead conductor is excellent in electroconductivity, when content of an additive element is adjusted in the range with which the electrical conductivity satisfy | fills the above-mentioned specific range, or manufacturing conditions, such as plastic working and heat processing, are adjusted.

The above lead conductors are thin and thin and difficult to break, and are excellent in conductivity. Therefore, non-aqueous electrolyte batteries such as lithium ion secondary batteries used for power sources of portable devices and other power storage devices It can utilize suitably as a structural member.

Furthermore, although the above lead conductor contains Mg, which is considered to be more easily eluted into the electrolyte than Al, it exists as a compound with Mg (Mg ₂ Si) by containing it in a specific range together with Si, thereby storing power. It was found that when assembled in a device, it also has excellent resistance to electrolytes. The presence of a resin layer between the lead conductor and the container of the power storage device is also expected to make it difficult to elute the constituent components of the lead conductor and contribute to improvement in resistance to the electrolytic solution. Also from these points, the lead conductor can be suitably used as a constituent member of a power storage device such as a nonaqueous electrolyte battery.

(2) As an example of the above lead conductor, there is a form in which the 0.2% proof stress is 40 MPa or more.

In the above form, the 0.2% proof stress satisfies a specific range, the proof stress is sufficiently high, and even if it is thin and thin, it is difficult to break.

(3) As an example of the lead conductor, a form having a thickness of 0.03 mm to 0.1 mm and a width of 1 mm to 10 mm can be given.

Although the above-mentioned form is thin and narrow, it is not too thin or too narrow, and is difficult to break. Moreover, since the said form is thin and thin, it can respond to the request | requirement of thickness reduction and size reduction of an electric power storage device.

(4) As an example of the above lead conductor, a form in which the diffusion resistance value is 5 × 10 ⁵ Ω · cm ⁻² or more can be mentioned. The diffusion resistance value is measured as follows.
A sample in which a part of the lead conductor is covered with a predetermined resin is used as a sample, and the formation position of the resin and the counter electrode in the sample are brought into contact with the electrolyte used in the power storage device, and the electrolyte is maintained at 60 ° C. Maintain for 1 week. After one week, the AC impedance spectrum of the sample is measured, and the resistance value of the sample is obtained based on the measured AC impedance spectrum. The obtained resistance value is defined as a diffusion resistance value. In a lead conductor with a resin having a coating resin layer to be described later, the diffusion resistance value may be measured by regarding the coating resin layer as the predetermined resin.

Since the diffusion resistance value is high even if the above-described form is in contact with a high-temperature electrolyte solution for a long time via the predetermined resin, it can be said that the constituent elements of the lead conductor are difficult to elute into the electrolyte solution over time. Therefore, the above-mentioned form is not easily broken even if it is thin and narrow, and is excellent in resistance to the electrolytic solution.

(5) As an example of the above-described lead conductor, a mode in which at least a part of the surface of the lead conductor is provided with a surface treatment portion on which one kind selected from chemical conversion treatment, boehmite treatment, alumite treatment, and etching is applied. It is done.

The surface treatment part has fine unevenness and excellent adhesion to the resin layer, and the lead conductor and the resin layer are difficult to peel off even if the resin layer formation area in the lead conductor is bent or shocked . The above-described form is not easily broken even if it is thin and thin, and the above-mentioned diffusion resistance value is further enhanced in that the resin layer is in close contact, and the resistance to the electrolytic solution is superior.

(6) As an example of the lead conductor, the aluminum alloy contains 0.005% by mass or more in total of one or more elements selected from Cu, Fe, Cr, Mn, Zn, Ni, Ag, and Zr. The form containing below mass% is mentioned.

In the above-mentioned form, in addition to Si and Mg, the elements listed above are contained in a specific range, so that the strength is easily increased and the material is not easily broken.

(7) As an example of the lead conductor, the aluminum alloy contains at least one of Ti of 0.01% by mass to 0.05% by mass and B of 0.001% by mass to 0.008% by mass. A form is mentioned.

Both Ti and B have the effect of making the crystal of the aluminum alloy fine during casting. In the above embodiment, in addition to Si and Mg, Ti and B are contained in a specific range, so that the constituent metal of the lead conductor can be an aluminum alloy having a fine crystal structure, and the strength becomes higher. Easy to break.

(8) As an example of the lead conductor, the lead conductor includes a coating resin layer bonded to a fixed region of the lead conductor with the container, and the coating resin layer has a multilayer structure made of different resins. The form whose total thickness is 20 micrometers or more and 300 micrometers or less is mentioned.

The coating resin layer is interposed between the lead conductor and the container of the power storage device and functions as an insulator. If the coating resin layer has a multilayer structure, it can contain resins of various materials, particularly resins having excellent adhesion. Even if the coating resin layer has a multi-layer structure, a thin lead conductor with a resin can be obtained as long as the thickness thereof is within the specific range described above. Therefore, the said form can ensure insulation with a container and contributes to thickness reduction of an electric power storage device. When this coating resin layer is provided in the surface treatment portion of (5) above, it is preferable because of excellent adhesion to the lead conductor as described above.

(9) A power storage device according to an aspect of the present invention includes the lead conductor according to any one of (1) to (8) above.

Even if the lead conductor provided in the above power storage device is thin and thin, the lead conductor is not easily broken when it is bent during the manufacturing process or when it is subjected to an impact by dropping it at any time. Therefore, when the power storage device is used as a power source for portable equipment, it is possible to reduce a decrease in yield due to breakage of the lead conductor or to maintain the lead conductor having excellent conductivity for a long period of time. , Can exchange power with the outside.

[Details of the embodiment of the present invention]
Hereinafter, a lead conductor according to an embodiment of the present invention and a power storage device according to an embodiment of the present invention will be described with reference to the drawings as appropriate. In the figure, the same reference numerals indicate the same names.

(Lead conductor)
The lead conductor 1 (FIGS. 1 and 2) of the embodiment is a conductive member used in a power storage device (nonaqueous electrolyte battery 10 in FIG. 1), and includes a positive electrode 14 and a negative electrode 15 (see FIG. 1) housed in a container 11. 2) and an external member (not shown) are electrically connected to be used for power transfer. The lead conductor 1 is typically a rectangular metal strip, and is used in a state where the resin layer is in contact with, preferably in close contact with, at least a fixed region of the surface with the container 11. The resin layer is at least one of a coating resin layer 22 described later, an inner resin layer 112 (FIG. 2) provided in the container 11 itself, and a bonding resin layer (not shown) separately bonded between the lead conductor 1 and the container 11. (Hereinafter, simply referred to as a resin layer).

One feature of the lead conductor 1 according to the embodiment is that it is made of an aluminum alloy having a specific composition containing Mg and Si in a specific range. Hereinafter, the composition of this aluminum alloy will be described first, and then the characteristics and structure of the lead conductor 1 will be described.

Composition The aluminum alloy constituting the lead conductor 1 of the embodiment contains 0.1% by mass or more and 1.2% by mass or less of Si, and Mg contains Mg / Si in a mass ratio of 0.8 or more and 2.7. An Al—Mg—Si based alloy that is contained in a range satisfying less than 1.5% by mass below, the balance being Al (aluminum) and inevitable impurities. In terms of Mg / Si, the lower limit of the Mg content is 0.08% by mass or more.
Or the aluminum alloy which comprises the lead conductor 1 of embodiment contains Si and Mg in the above-mentioned specific range, and is selected from Cu, Fe, Cr, Mn, Zn, Ni, Ag, and Zr. It is an Al—Mg—Si based alloy containing a total of 0.005 mass% or more and 1 mass% or less of elements (hereinafter sometimes referred to as specific elements), with the balance being Al and inevitable impurities.
Hereinafter, the element content indicates mass%.

..Si (silicon) and Mg (magnesium)
An Al—Mg—Si alloy containing 0.1% or more of Si and 0.08% or more of Mg has high tensile strength and 0.2% yield strength, and is excellent in strength and yield strength. Such an Al—Mg—Si-based alloy can be expected to further improve the strength and yield strength by age hardening when it is subjected to an aging treatment in the production process. Such an Al—Mg—Si based alloy may improve in strength over time due to natural aging. Such a high-strength Al—Mg—Si-based alloy can maintain high strength even when, for example, softening is performed after plastic working to increase toughness or conductivity. In this case, it can have high strength, high toughness, and high conductivity. Even if the lead conductor 1 made of such an Al—Mg—Si alloy is thin and thin, it is difficult to break when subjected to predetermined bending or impact.

Such an Al—Mg—Si alloy tends to have higher strength as the Mg and Si contents are higher. For example, such an Al—Mg—Si-based alloy has a Si content of 0.2% or more, further 0.3% or more, 0.35% or more, a Mg content of 0.1% or more, 0% .2% or more, and further 0.3% or more.

In such an Al—Mg—Si based alloy, if the content of Mg and Si is too large, the conductivity decreases (especially when Mg is excessive), the precipitate containing Mg and Si is too much or coarse. Or the fracture starting from the precipitate is likely to occur. Therefore, the Si content is 0.9% or less, further 0.8% or less, 0.7% or less, and the Mg content is 1.4% or less, 1.2% or less, and further 1.0% or less. can do.

Such an Al—Mg—Si based alloy has a mass ratio of Mg to Si of Mg / Si, and since this Mg / Si is 0.8 or more, there are many metal components and the conductivity tends to be high. The lower limit of Mg / Si can be 0.9 or more, further 0.95 or more, and 1 or more. Since Mg / Si is 2.7 or less, precipitates containing Mg and Si can be appropriately present and the strength tends to increase. The upper limit of Mg / Si can be 2.6 or less, further 2.5 or less, or 2.0 or less.

It is considered that Mg alone is easier to elute into the electrolyte than Al. Although the Al—Mg—Si based alloy contains Mg, it contains Mg in a specific range with respect to Si and less than 1.5%, so that Mg is a compound with Si (Mg ₂ Si ). Since Mg ₂ Si is difficult to pass electricity, it is considered that short circuiting caused by elution of Mg can be prevented. The inventors of the present invention configured a two-electrode electrochemical cell of a working electrode made of aluminum alloy or pure aluminum having various compositions and a counter electrode made of platinum, and both electrodes were immersed in an electrolyte solution to obtain a predetermined voltage. The amount of current that flows when sapphire was measured was measured. As a result, when Si is contained in the specific range described above, Mg / Si exceeds 2.7, and Mg having an amount of 1.5% by mass or more is excessive, the amount of current is very large. / Si is 2.7 or less and Mg is less than 1.5% by mass (for example, Al-0.65% Si-0.9% Mg, Mg / Si≈1.4) It has been confirmed that the amount of current is about 1/10 or less of the excess Mg, which is almost the same as that of pure aluminum. In consideration of resistance to the electrolytic solution, the lead conductor 1 of the embodiment defines the Si content, the Mg content, and Mg / Si.

.. Other additive elements The aluminum alloy constituting the lead conductor 1 of the embodiment is likely to have high strength when it contains the above-mentioned specific element in a specific range in addition to Mg and Si. Of the above-mentioned specific elements, Cu has little decrease in conductivity and can improve strength. Although Fe, Cr, Mn, Ni, and Zr have a large decrease in conductivity, the effect of improving the strength is high. Zn and Ag have little decrease in electrical conductivity and have a certain degree of strength improvement effect. Either a form containing only one kind of these elements or a form containing two or more kinds can be used.

Such an aluminum alloy has high strength and hardly breaks when the total content of the specific elements is 0.005% or more. The greater the total content, the higher the strength, and the lower limit can be 0.01% or more, further 0.05% or more, 0.1% or more.

If the total content of the specific element is 1% or less, such an aluminum alloy is excellent in conductivity by reducing the decrease in conductivity. Here, when the constituent components of the lead conductor 1 are eluted in the electrolytic solution, there is a possibility that the positive electrode 14 and the negative electrode 15 are short-circuited or the characteristics of the power storage device are deteriorated due to the eluted components. If the total content is 1% or less, the elution of the constituent components can be sufficiently reduced. In the lead conductor 1 attached to the power storage device as described above, the elution of the constituent components can be more effectively reduced if the resin layer is in close contact. The upper limit of the total content can be 0.9% or less, further 0.8% or less, or 0.7% or less.
Examples of the content of each element include the following.
Cu 0.01% to 0.9%, further 0.03% to 0.8% Fe 0.005% to 0.9%, further 0.01% to 0.5% Cr 0.005 % To 0.8%, further 0.01% to 0.7% Mn 0.005% to 0.8%, further 0.01% to 0.7% Zn, Ni, Ag, Zr Total 0.005% or more and 0.2% or less, and in total, 0.005% or more and 0.15% or less

..Ti (titanium), B (boron)
In addition to Mg and Si or in addition to Mg and Si and the specific element, the aluminum alloy can easily increase the strength when it contains at least one of Ti and B in a specific range. This is because Ti and B have an effect of making the crystal of the aluminum alloy fine at the time of casting, and the strength is enhanced if it has a fine crystal structure. Although the form containing B may be sufficient as an aluminum alloy, the refinement | miniaturization effect of a crystal | crystallization is easier to obtain if it is the form containing Ti, and also the form containing both Ti and B.

An aluminum alloy is more likely to obtain a crystal refinement effect as the content of Ti or B is larger, but if it is too much, the electrical conductivity is lowered. Moreover, it is thought that the refinement | miniaturization effect of a crystal | crystallization is saturated with the content of Ti and B about the following upper limit values. From this, the Ti content of the aluminum alloy is 0.01% or more and 0.05% or less, 0.015% or more and 0.045% or less, and further 0.02% or more and 0.04% or less. be able to. Examples of the B content of the aluminum alloy include 0.001% to 0.008%, 0.003% to 0.007%, and further 0.004% to 0.006%.

-Structure As the structure of the aluminum alloy constituting the lead conductor 1, the fine crystal structure described above can be cited. For example, the average crystal grain size may be 1 μm or more and 50 μm or less, 2 μm or more and 40 μm or less, and further 30 μm or less. When the lead conductor 1 has such a fine crystal structure, the lead conductor 1 is excellent in strength and is not easily broken even if it is thin and thin, and the electrolyte does not easily penetrate into the lead conductor 1. It is expected that the amount of the constituent component eluted into the electrolytic solution is reduced and the resistance to the electrolytic solution is easily increased. The crystal grain size may be controlled to a predetermined size by adjusting the content of the above-described additive elements, the conditions of plastic working in the manufacturing process, the heat treatment conditions, and the like.

-Mechanical characteristics-Tensile strength The lead conductor 1 of the embodiment is characterized in that the tensile strength is 100 MPa or more and 220 MPa or less. Since the lead conductor 1 has a sufficiently high tensile strength, it is difficult to break even if it is thin and narrow. Since the higher the tensile strength, the better the strength and the more difficult it is to break, the lower limit of the tensile strength can be 110 MPa or more, further 120 MPa or more, 125 MPa or more. Since the lead conductor 1 is not too high in tensile strength, the electrical conductivity is reduced due to strain introduced during plastic working, and the electrical conductivity is excellent, and the toughness such as elongation is also excellent. Therefore, the lead conductor 1 can have a tensile strength of 210 MPa or less, further 200 MPa or less, and 190 MPa or less.

.. Strength The lead conductor 1 of the embodiment has high tensile strength and typically excellent strength, and it is difficult to break even if it is thin and narrow. Specifically, a lead conductor 1 having a 0.2% proof stress satisfying 40 MPa or more can be mentioned. The lead conductor 1 has a tendency that the higher the yield strength, the more difficult it is to break, and the 0.2% yield strength can be set to 45 MPa or more, further 50 MPa or more, 55 MPa or more. When the 0.2% proof stress is too high, the tensile strength tends to be too high, and there is a concern about the above-described decrease in conductivity and toughness.
The upper limit of 0.2% proof stress is about 100 MPa or less.

-Elongation The lead conductor 1 of the embodiment is excellent in strength such as tensile strength and proof stress, and is typically excellent in toughness such as elongation, and it is difficult to break even if it is thin and narrow. Specifically, the lead conductor 1 satisfying a breaking elongation of 5% or more can be mentioned. The lead conductor 1 tends to be more difficult to break as the elongation is higher, and the elongation at break can be 6% or more, further 7% or more, or 8% or more. When the elongation at break of the lead conductor 1 is too high, the tensile strength and the 0.2% proof stress tend to be too low, and there is a concern that the strength may decrease. The upper limit of breaking elongation is about 40% or less.

-Conductivity The lead conductor 1 of the embodiment is excellent in strength and toughness, and is also excellent in conductivity, and has a conductivity satisfying 50% IACS or more. The lead conductor 1 preferably has higher electrical conductivity, and the electrical conductivity can be 51% IACS or higher, further 52% IACS or higher, or 53% IACS or higher.

-Size The size (thickness, width, length) of the lead conductor 1 of the embodiment can be selected as appropriate. The lead conductor 1 having a small thickness and a narrow width can be suitably used as a constituent member of a power storage device for which a reduction in thickness and size is desired. Examples of the thin and narrow lead conductor 1 include those having a thickness of 0.03 mm to 0.1 mm and a width of 1 mm to 10 mm. The length of the lead conductor 1 may be adjusted by appropriately cutting before assembling to the power storage device.

If the thickness is 0.03 mm or more, it is difficult to break even if the width is as thin as about 1 mm. The thickness can be 0.035 mm or more, and further 0.04 mm or more. If thickness is 0.1 mm or less, it can contribute to thickness reduction and size reduction of an electric power storage device. The thickness can be 0.08 mm or less, further 0.07 mm or less, and 0.05 mm or less.

If the width of the lead conductor 1 is 1 mm or more, it is difficult to break even if the thickness is as thin as about 0.03 mm. The lead conductor 1 can have a width of 2 mm or more, and further 3 mm or more. If the width | variety of the lead conductor 1 is 10 mm or less, it can contribute to size reduction of an electric power storage device. The lead conductor 1 can have a width of 9 mm or less, further 8 mm or less, or 7 mm or less.

-Resistance to electrolyte solution The lead conductor 1 of the embodiment is also excellent in resistance to the electrolyte solution, and the constituent components of the lead conductor 1 are difficult to elute into the electrolyte solution. When the above-described diffusion resistance value (see also Patent Document 1) is used as a parameter indicating this characteristic, the lead conductor 1 of the embodiment has a high diffusion resistance value of 5 × 10 ⁵ Ω · cm ⁻² (= 5 × 10 ⁵ Ω / cm ² ) or more is mentioned. It is considered that the lead conductor 1 has a higher diffusion resistance value, so that the amount of the above constituent components eluted into the electrolyte solution is smaller and the resistance to the electrolyte solution is better, and the diffusion resistance value is 6 × 10 ⁵ Ω · cm ⁻² or more, Furthermore, it is preferable to satisfy 7 × 10 ⁵ Ω · cm ⁻² or more and 7.5 × 10 ⁵ Ω · cm ⁻² or more. In order to increase the diffusion resistance value, it is preferable to provide a specific surface treatment section described later in the contact area with the resin layer.

-Surface treatment part When the lead conductor 1 of embodiment is provided with the surface treatment part by which the below-mentioned surface treatment was given to the fixed area | region with the container 11 at least on the surface of at least one part of the surface, Preferably both surfaces of a front and back, a resin layer Adhesion can be improved. The contact area of the lead conductor 1 with the electrolytic solution in the container 11 in the lead conductor 1 is reduced due to the closely adhered resin layer, and the components of the lead conductor 1 can be reduced from being eluted into the electrolytic solution. Such a lead conductor 1 has a high diffusion resistance value. Further, when the lead conductor 1 and the resin layer are in close contact with each other, the sealed state of the container 11 of the power storage device can be maintained satisfactorily, leakage of the electrolyte solution to the outside of the container 11, and intrusion of moisture from the outside into the container 11 Can be prevented.

Form in which the surface treatment part is provided only in the fixed region with the container 11 on the surface of the lead conductor 1 (form in which surface treatment is performed only in the fixed area), and form in which the surface treatment part is provided on the entire front and back surfaces of the lead conductor 1 Surface treatment is applied to the end surface / side surface connecting the back surface), and the surface treatment portion is provided on the entire outer surface of the lead conductor 1 (surface treatment is applied to all of the end surface / side surface connecting the front and back surfaces and the front and back surfaces. Can be used.

Examples of the surface treatment include chemical conversion treatment, boehmite treatment, alumite treatment, etching, blast treatment, and brush polishing. As the conditions for each treatment, known conditions that have been applied to conventional lead conductors can be used.

In particular, when the lead conductor 1 includes a surface treatment portion to which one type selected from chemical conversion treatment, boehmite treatment, alumite treatment, and etching is provided, the lead conductor 1 is more excellent in adhesion to the resin layer, depending on the treatment conditions. It tends to be the lead conductor 1. When the lead conductor 1 includes a surface treatment portion subjected to chemical conversion or etching, the lead conductor 1 is further excellent in adhesion to the resin layer. By being superior in the adhesion between the lead conductor 1 and the resin layer, it is possible to reduce the elution amount of the constituent components, increase the diffusion resistance value, maintain a good sealing state, and the like. As for the surface roughness of this surface treatment part, 0.1 micrometer or more and 0.5 micrometer or less are mentioned by arithmetic mean roughness Ra, for example.

Covering resin layer As an example of the lead conductor 1 of the embodiment, a coating bonded to a fixed region between the main body of the lead conductor 1 made of an aluminum alloy having the above-described specific composition and the container 11 in the main body of the lead conductor 1 A lead conductor with resin 20 including the resin layer 22 is exemplified. The covering resin layer 22 functions as an insulator between the main body of the lead conductor 1 and the metal layer 110 when the container 11 of the power storage device includes the metal layer 110. For the formation of the coating resin layer 22, known manufacturing conditions for lead conductors with resin can be used.

A typical example of the constituent material of the coating resin layer 22 is thermoplastic polyolefin. Specifically, polyethylene, acid-modified polyethylene, polypropylene, ethylene vinyl acetate copolymer, acid-modified polypropylene (for example, maleic anhydride-modified polypropylene), ionic polymers such as ionomer, maleic acid-modified polyolefin (for example, maleic acid-modified polyolefin) Low density polyethylene), or mixtures thereof.
Examples of the ionomer include those obtained by crosslinking a copolymer such as ethylene and methacrylic acid with a metal ion such as Na, Mg, K, Ca, or Zr, a metal complex, or a cation such as an ammonium salt.

The covering resin layer 22 can be a single layer structure or a multilayer structure made of resins having different components and cross-linked states. Examples of the coating resin layer 22 having a multilayer structure include a two-layer structure including an adhesive layer and a surface layer. For example, the adhesive layer includes the above-described thermoplastic polyolefin, and the surface layer includes the above-described thermoplastic polyolefin cross-linked (for example, the same resin as the constituent resin of the adhesive layer and cross-linked).

In the coating resin layer 22 having a multilayer structure, for example, both the adhesion between the main body of the lead conductor 1 and the coating resin layer 22 and the adhesion between the container 11 and the coating resin layer 22 can be selected by selecting a component, a crosslinked state, and the like. Can be enhanced. As a result, even if the portion having the coating resin layer 22 in the lead conductor 20 with resin is bent or subjected to an impact, the container 11 and the coating resin layer 22 are disposed between the main body of the lead conductor 1 and the coating resin layer 22. The covering resin layer 22 is difficult to peel off. The power storage device including such a lead conductor 20 with resin can reduce the amount of elution into the electrolyte in the constituent components of the main body of the lead conductor 1 by the coating resin layer 22 that is in close contact with the main body of the lead conductor 1. The sealed state of the container 11 can be maintained satisfactorily. When the main body of the lead conductor 1 includes the above-described surface treatment portion, it is preferable that the surface treatment portion includes the coating resin layer 22 because the adhesion of the coating resin layer 22 is more excellent.

If the coating resin layer 22 is thick to some extent, the coating resin layer 22 is not easily damaged when the lead conductor 20 with resin is bent or subjected to an impact, and conversely, the coating resin layer 22 is not too thick. Thus, the lead conductor 20 with resin can be thinned. The thickness of the coating resin layer 22 is, for example, 20 μm or more and 300 μm or less, and can be 30 μm or more and 290 μm or less, 40 μm or more and 280 μm or less, and 50 μm or more and 200 μm or less. This thickness is the thickness of the coating resin layer 22 provided on one surface of the main body of the lead conductor 1 when the coating resin layers 22 are provided on the front and back surfaces of the main body of the lead conductor 1, respectively. If the layer 22 has a multilayer structure, the total thickness is taken.

-Use Although the lead conductor 1 of embodiment and the lead conductor 20 with resin can be utilized for any of the positive electrode of a power storage device, and a negative electrode, it is suitable for the lead conductor for positive electrodes.

Manufacturing method The lead conductor 1 having the above-mentioned specific composition and having high strength and excellent conductivity, and the lead conductor 1 also excellent in elongation are prepared by preparing an aluminum alloy having a specific composition, and plasticity such as rolling. Manufactured by processing and heat treatment.
Examples of the material used for plastic working include a continuous cast material, a billet cast material, and an extruded material obtained by extruding a continuous cast rolled material.
The heat treatment includes softening treatment, and plastic processing can be performed before and after the softening treatment. Examples of the lead conductor 1 include soft materials and ½ hard materials. The ½ hard material can be manufactured by performing plastic processing to some extent after the softening treatment, or by performing a softening treatment to such an extent that the strength does not decrease too much after the plastic working. At least the heat treatment conditions and the degree of plastic working are adjusted so that the tensile strength and the electrical conductivity satisfy the specific ranges described above.

The lead conductor 20 with a resin including the coating resin layer 22 is preferably manufactured by, for example, the following manufacturing method (A) or (B) because the adhesiveness of the coating resin layer 22 is excellent.
(A) Fabricate the cast plate ⇒ Roll the cast plate ⇒ Apply heat treatment (softening treatment) to the rolled plate ⇒ Perform surface treatment ⇒ Cut the treated plate into strips ⇒ Form a coating resin layer (B) Continuous casting Create rolled material (wire rod) ⇒
Extrude wire rod into plate by conform extrusion ⇒ Roll the extruded plate ⇒
Apply heat treatment (softening treatment) to the rolled plate ⇒ Apply surface treatment ⇒ Cut the processed plate into strips ⇒
Form a coating resin layer

For details of the surface treatment, refer to the section of the surface treatment section described above. The details of the coating resin layer 22 may be referred to the section of the coating resin layer 22 described above.

Aging treatment can be performed at any time before softening treatment. When the aging treatment is performed, the solution treatment can be performed at any time before the aging treatment. When continuous casting is performed, the solution treatment can be omitted. A compound containing Mg and Si is precipitated by aging treatment, and the strength is improved by dispersion strengthening by the precipitates and the electrical conductivity is improved by reducing the solid solution amount of Mg and Si in Al. Can do.

.. Process before rolling When the cast plate of (A) is a continuous cast material, it has the advantages that it is easy to refine crystals by rapid cooling, a long material is obtained, and a supersaturated solid solution is easily obtained by rapid cooling.
By subjecting the continuous cast rolled material (B) to conform extrusion, an extruded plate having a desired shape and size can be easily formed, and an extruded plate having a fine crystal structure can be obtained.
Since the material used for rolling has a fine structure, it is excellent in plastic workability and can be rolled well.

.. Rolling process Hot rolling or cold rolling is performed by adjusting the rolling reduction so as to obtain a rolled sheet having a desired thickness (which may be the thickness of the lead conductor 1). By performing cold rolling, the crystal can be made finer, and even when heat treatment is performed at an appropriate time, the lead conductor 1 having a fine crystal structure can be easily obtained. Intermediate heat treatment can be performed during rolling. When the intermediate heat treatment is performed, the plastic workability can be improved.

・ ・ Heat treatment process Heat treatment such as softening treatment, aging treatment, and solution treatment can be either continuous treatment for long materials or batch treatment in which the materials are sealed in a heating container such as an atmospheric furnace. Can also be used. Examples of the continuous treatment include a direct energization method, an indirect energization method, and a furnace method. Control parameters such as holding temperature, holding time, material supply speed, current value, furnace temperature, and the like are adjusted in accordance with the continuous processing method so that the tensile strength and the electrical conductivity become desired values.

An example of conditions for solution treatment, aging treatment, and softening treatment by batch treatment is shown below.
Solution treatment Holding temperature: 500 ° C. or more and 580 ° C. or less, Holding time: 0.01 hour or more and 10 hours or less Aging treatment Holding temperature: 100 ° C. or more and 250 ° C. or less, Holding time: 2 hours or more and 20 hours or less Softening treatment Holding temperature: 250 to 500 ° C., holding time: 0.5 to 6 hours

If the atmosphere of the heat treatment is an atmosphere having a low oxygen content, generation of an oxide film can be suppressed. Specific atmospheres include an air atmosphere and a non-oxidizing atmosphere. Examples of the non-oxidizing atmosphere include a reduced pressure atmosphere (vacuum atmosphere), an inert gas atmosphere such as nitrogen and argon, and a reducing gas atmosphere containing hydrogen and carbon dioxide gas.

.. Separation process The produced aluminum alloy plate having a predetermined thickness is cut according to a predetermined width of the lead conductor 1 to form a strip. Here, even if the produced aluminum alloy plate is a thin plate of, for example, 0.1 mm or less, the cross-sectional area of the wide thin plate is large to some extent, so that it is difficult to break and is easy to handle. When this wide thin plate is cut into, for example, a width of 10 mm or less to form a narrow strip, the cross-sectional area is reduced. However, this thin and narrow strip is made of the aluminum alloy having the specific composition described above, and the tensile strength and the electrical conductivity satisfy a specific range, so that the breaking load is large and it is difficult to break. Accordingly, this thin and narrow strip (an example of the lead conductor 1 of the embodiment) is not easily broken and easy to handle in the manufacturing process of the lead conductor 1 itself, and is bent or shocked in the manufacturing process of the power storage device. It is difficult to break even if it is received. If the strip is long, it may be appropriately cut to a predetermined length.

(Power storage device)
The power storage device according to the embodiment electrically connects a positive electrode, a negative electrode, an electrolyte, a container that stores these, a positive electrode and an external member, and a negative electrode and an external member. One lead conductor. In the power storage device of the embodiment, one or two of the two lead conductors are the lead conductor 1 of the above-described embodiment (there may be a lead conductor 20 with resin).

Each lead conductor is arranged from the inside to the outside of the container, and a positive electrode or a negative electrode is connected to one end side, and an external member such as a circuit board is connected to the other end side by soldering or the like. A fixing area with the container is provided. A resin layer (at least one of the above-described coating resin layer 22, inner resin layer 112, and bonding resin layer) is interposed between the lead conductor fixing region and the container. *

Specific examples of the power storage device of the embodiment include a non-aqueous electrolyte battery using a non-aqueous electrolyte, an electric double layer capacitor, and an aqueous electrolyte battery using water as a main solvent of the electrolyte. Known techniques can be applied to the basic configuration of the nonaqueous electrolyte battery, the electric double layer capacitor, the aqueous electrolyte battery, the material of each component, and the like.

1 and 2 show an example of a nonaqueous electrolyte battery 10.
The nonaqueous electrolyte battery 10 includes a positive electrode 14, a negative electrode 15, a separator 13 impregnated with an electrolytic solution (here, a nonaqueous electrolytic solution), a bag-like container 11 that houses these battery elements, and a container 11. And two lead conductors 20 with resin fixed to each other. At least one of the lead conductors 20 with resin (for example, positive electrode) includes a main body of the lead conductor 1 made of an aluminum alloy having the specific composition described above, and a coating resin layer 22 bonded to the front and back surfaces of the main body of the lead conductor 1. Prepare. As the negative electrode lead conductor (main body), for example, one made of pure nickel, pure copper, pure nickel-plated pure copper, or the like can be used.
The covering resin layer 22 shown in FIG. 2 has a double structure including an adhesive layer 220 in contact with the main body of the lead conductor 1 and a surface layer 222 in contact with the inner surface of the container 11.

The positive electrode 14 and the negative electrode 15 of the nonaqueous electrolyte battery 10 are typically an active material layer composed of a powder molded body containing an active material, etc., and are a current collector 16 and a current collector composed of metal foil. 17 is formed on each. The current collector 16 (or current collector 17) and the main body of the lead conductor 1 are connected by, for example, a lead wire 19 (FIG. 2).
As the positive electrode and the negative electrode of the electric double layer capacitor, solid activated carbon is exemplified.

The container 11 is typically provided with a metal layer and a resin layer. The container 11 of FIG. 2 shows the example comprised from the double-sided multilayer film provided with the inner side resin layer 112, the metal layer 110, and the outer side resin layer 114 in order from the inner side. The container 11 is sealed by heat-sealing the peripheral portion of the double-sided multilayer film, and is formed into a bag shape as shown in FIG. In the fixing region of the lead conductor 1 in the container 11, the inner resin layer 112 of the container 11 and the covering resin layer 22 (here, the surface layer 222) of the lead conductor 20 with resin are heat-sealed, thereby providing the lead conductor with resin. 20 is fixed to the container 11 and the container 11 is sealed.

[Test Example 1]
Narrow strips were made from aluminum alloy plates of various compositions, and the mechanical properties and conductivity were examined.

The strip material of each sample was manufactured as follows.
A raw material having the composition shown in Table 1 (remainder Al and inevitable impurities) is prepared, and an aluminum alloy plate having a thickness of 0.05 mm is manufactured by the following step (I) or (II). Each obtained aluminum alloy plate is cut into a width of 5 mm or a width of 4 mm to obtain a narrow strip.
(I) Continuous casting ⇒ Conform extrusion ⇒ Cold rolling ⇒ Softening treatment (II) Billet casting ⇒ Solution treatment ⇒ Cold rolling ⇒ Softening treatment

Some samples are subjected to an aging treatment at an appropriate time during the cold rolling. The conditions for the aging treatment are a holding temperature of 180 ° C., a holding time of 16 hours, and “180 ° C. × 16 H” in Table 1.
A softening treatment (final heat treatment in this test) is performed after rolling. Table 1 shows the conditions of the softening treatment (softening temperature, atmosphere). In this test, the softening treatment was performed by batch treatment, and the softening temperature holding time was adjusted mainly using the tensile strength as an index.
Sample No. No softening treatment is performed on 1-103.

A tensile test (room temperature) was performed using a strip of 5 mm width among the strips of each sample prepared, and tensile strength (MPa), 0.2% proof stress (MPa), and elongation at break (%) were examined. . The results are shown in Table 2. The tensile test is performed based on JIS Z 2241 (2011).

The electrical conductivity (IACS%) was examined by a four-terminal method using a strip having a width of 5 mm among the strips of each prepared sample. The results are shown in Table 2.

Using the 4 mm wide strip of each sample strip, the bending test and the impact test were performed. The number of times of folding until the fracture occurred (times) and the energy (J / m) at the time of the fracture due to the impact were calculated. Examined. The results are shown in Table 2.

The bending test is performed as follows. As shown in FIG. 3, the sample S (strip) having a distance L between the scores of 30 mm is folded into two (see black arrows). Bending is performed so that the distance C between the ends of the sample S adjacent by folding is equal to twice the thickness of the sample S (0.05 mm in this example). Open the sample S folded in two and return it to its original position (see white arrow). This series of operations of folding and returning is considered as one time, and the number of times until it breaks is examined. It can be said that it is hard to break, so that there are many times.

The impact test is performed as follows. As shown in FIG. 4, a weight w is attached to the tip of a sample S having a distance L between the scores of 1 m (the left figure in FIG. 4), and after lifting the weight w upward by 1 m (the middle figure in FIG. 4), free fall (Right figure in FIG. 4). The weight (kg) of the maximum weight w at which the sample S does not break by this operation was measured, and the product value obtained by multiplying the weight by the gravitational acceleration (9.8 m / s ² ) and the drop distance 1 m was divided by the drop distance. Impact resistance is evaluated by the magnitude of the value (J / m or (N · m) / m). It can be said that the larger the impact value, the better the impact resistance and the more difficult it is to break.

As shown in Table 2, a sample No. composed of an Al—Mg—Si alloy having a specific composition containing Mg and Si in a specific range. 1-1-No. It can be seen that 1-11 has a tensile strength of 100 MPa or more and 220 MPa or less, an electrical conductivity of 50% IACS or more, high strength and excellent conductivity. Sample No. 1-1-No. No. 1-11 has a tensile strength of 120 MPa or more, and many samples have 130 MPa or more. Sample No. 1-1-No. Many of the samples 1-11 have a conductivity of 55% IACS or more, and further 56% IACS or more. These sample Nos. 1-1-No. Although 1-11 is a thin and narrow band material, it can be seen that it is difficult to break when bent or subjected to an impact. Sample No. with too much Mg It can be seen that 1-101 is very low in electrical conductivity (less than 45% IACS) and easily breaks. Sample No. with too little Si 1-102 shows that the tensile strength is too low (here, less than 100 MPa, and further 90 MPa or less), and it tends to break. Sample No. not softened. It can be seen that 1-103 has an excessively high tensile strength (here, more than 220 MPa, and more than 300 MPa), and is easily broken. Sample No. with too few added elements 1-104 shows that the tensile strength is too low (here, less than 100 MPa, and further 90 MPa or less), and it tends to break.

In this test, a thin and narrow strip having a thickness of 0.1 mm or less and a width of 10 mm or less is bent with a bending radius equal to or less than the thickness of the sample, but is further repeatedly bent. However, sample no. 1-1-No. It can be seen that 1-11 has a number of folding times of 5 or more and is difficult to break. Here, for example, when a lead conductor provided in a power storage device such as a lithium ion secondary battery is bent into a predetermined shape and fixed to an external member, an operation for opening the bent portion is performed in the subsequent manufacturing process. There is usually no such thing. However, there is a possibility that a force is applied to open the bent portion when the lead conductor receives an impact, for example, by dropping portable devices including the power storage device. Sample No. 1-1-No. Any of the thin and thin strips of 1-11 are not easily broken by repeated bending, so even if they are used as lead conductors for power storage devices such as lithium ion secondary batteries and are subjected to impacts such as dropping. It is expected that the predetermined bent shape can be satisfactorily maintained without breaking.

Also, in this test, it can be seen that it is difficult to break even when a thin impact material having a thickness of 0.1 mm or less and a width of 10 mm or less is subjected to a large impact load of 2.0 J / m or more. Sample No. having such excellent impact resistance. 1-1-No. Any of the thin and thin strips of 1-11 is expected to hardly break even when it is used as a lead conductor of a power storage device such as a lithium ion secondary battery and receives an impact such as dropping. Furthermore, a thin and narrow strip of a sample group having a specific composition excellent in impact resistance is expected to be difficult to break even when subjected to an impact in a state of being bent into a predetermined shape as described above. .

As one of the reasons why such a result was obtained, sample No. 1-1-No. All of 1-11 are considered to have high tensile strength and excellent elongation in addition to satisfying a specific range of tensile strength. Specifically, Sample No. 1-1-No. 1-11 has a 0.2% proof stress of 40 MPa or more, further 50 MPa or more, many samples have 60 MPa or more, and elongation at break of 5% or more, further 6% or more. As another reason, sample No. 1-1-No. It is conceivable that 1-11 has a fine crystal structure, in particular, a sample containing at least one of Ti and B in a specific range has a finer crystal structure. Sample No. 1-1-No. When the crystal grain size was examined by observing the section 1-11 with an optical microscope, all of the samples had an average crystal grain size of 50 μm or less, and the samples containing Ti and B were finer crystals. The average crystal grain size is determined by a cutting method in accordance with JIS G 0551 (steel-crystal grain size microscopic test method, 2005).

In addition, the following can be understood from this test.
-Increasing the content of Mg or Si within a specific range or containing a specific additive element such as Cu within a specific range makes it easier to increase the tensile strength and the yield strength.
-Even if it is thin and narrow, it can be manufactured by controlling the conditions of plastic working and heat treatment while using a specific component as well as having a high strength, being difficult to break, and excellent in electrical conductivity.
For example, Sample No. having the same composition. 1-4 and Sample No. Comparing with 1-103, it can be seen that a plastic material having a high strength and excellent elongation can be obtained by performing a softening treatment. Sample No. having the same composition. 1-4 and Sample No. Comparing with 1-5, it can be seen that an aging treatment can be performed at an appropriate time to obtain a superior strength.

[Test Example 2]
Sample No. produced in Test Example 1 Using a strip made of an aluminum alloy having a composition of 1-11, a simulated sample of a lead conductor with resin was prepared, and the diffusion resistance value and the bonding strength of the resin were examined.

A simulated sample of the lead conductor with resin was prepared as follows.
Sample No. shown in Table 1 1-11 aluminum alloy plate (Mg: 0.48 mass%, Si: 0.19 mass%, Ti: 0.02 mass%, B: 0.005 mass%, thickness 0.05 mm) width A thin and narrow strip is prepared by cutting to 10 mm and a length of 45 mm, and the resin is joined after the surface treatment shown in Table 3 or without the surface treatment.

The sample subjected to the surface treatment is subjected to the surface treatment on the entire front and back surfaces of the strip (the entire front and back surfaces are the surface treatment portion), and the end surface and side surfaces of the strip are not subjected to the surface treatment. In addition, you may cut | disconnect the said sample, after giving surface treatment to the front and back of the aluminum alloy plate before a cutting | disconnection.

The details of the surface treatment shown in Table 3 are as follows.
The chemical conversion treatments I, III, and IV are chemical conversion treatments using commercially available chemical conversion treatment solutions capable of forming ionomers, and the average thickness of chemical film formation is the values shown in Table 3 (10 nm, 30 nm, 300 nm). The immersion time of the chemical conversion treatment solution is adjusted.
Chemical conversion treatment II is a chromate treatment using a commercially available treatment solution.
The roughening I and II are etching treatments using a commercially available alkaline etching solution, and the etching time is adjusted so that the average pit depth becomes the values shown in Table 3 (1 μm, 0.5 μm).
Boehmite I and II are boehmite treatments using pure water at 95 ° C., and the treatment times are different as shown in Table 3 (15 minutes, 20 seconds).
Alumite I and II are anodized using an aqueous sulfuric acid solution, and the treatment time is adjusted so that the average thickness of the alumite layer is 0.5 μm. In anodized I, sealing treatment is not performed after anodization, and in anodized II, sealing treatment is performed after anodization.
Blasting is a blasting process performed under the conditions shown in Table 3 (shot material: # 120 alumina particles, pressure: 0.3 MPa) using a commercially available pneumatic blasting apparatus.

Each sample No. 1 subjected to the above surface treatment was used. 2-11-No. 2-18, no. 2-112 ~ No. No. 2-114 strip and sample No. No surface treatment. Resin is bonded to the front and back surfaces of the 2-111 strip.
As the resin to be joined in each sample, a double-structure resin film including an adhesive layer (thickness 25 μm) made of acid-modified polypropylene and a surface layer obtained by crosslinking acid-modified polypropylene is used. Two resin films are used for each sample so as to sandwich the front and back surfaces of the strip of each sample.
The thickness of the surface layer for each resin film used in each sample is adjusted so that the total thickness of the adhesive layer and the surface layer becomes “resin thickness” in Table 3.

Except for a predetermined region on the front and back surfaces of the band material of each sample, the band material is sandwiched between two resin films, and the resin film is bonded to the front and back surfaces of the band material by hot pressing. The joining conditions are heating temperature: 260 ° C., pressure: 0.2 MPa, and heating time: 10 seconds. By this step, a simulated sample of a lead conductor with resin in which a part of the strip is exposed from the resin is obtained.
In the simulated sample used for the measurement of the diffusion resistance value, a region on one edge side where the lead wire is connected in the strip (10 mm in the region on the upper edge side in FIG. 5 × 10 mm in length) is exposed from the resin film. Each resin film is 25 mm × length 45 mm.
In the simulated sample used for measuring the bonding strength of the resin, the regions on both sides of the strip are exposed from the resin film (regions on the left and right sides in FIG. 7). Each resin film is 5 mm × length 60 mm.

(Diffusion resistance value)
As shown in FIG. 5, an electrochemical measurement cell 300 is constructed using a simulated sample SS1 including a strip S1 simulating a main body of a lead conductor and a resin layer S22, a counter electrode 302, and an electrolytic solution 304. After the simulated sample SS1 is immersed in the liquid 304 for a predetermined time, a diffusion resistance value is calculated using an AC impedance spectrum (see also Patent Document 1). The results are shown in Table 3.

In any sample, the counter electrode 302 is a wire rod (diameter 0.5 mm × length 50 mm) made of pure aluminum containing 99.999% by mass of Al. As the counter electrode 302, various electrodes having sufficient resistance to the electrolytic solution 304 and excellent in potential stability can be used as appropriate.
In any sample, the electrolytic solution 304 is used as an electrolytic solution for a lithium ion secondary battery. Here, the electrolyte is LiPF ₆ (molar concentration of electrolyte: 1 mol / L) and the solvent is a mixed organic solvent of EC: DMC: DEC = 1: 1: 1 (V / V%) (manufactured by Kishida Chemical Co., Ltd.) Electrolyte). EC is ethylene carbonate, DMC is dimethyl carbonate, DEC is diethyl carbonate, and V / V% means volume ratio.

As shown in FIG. 5, lead wires are connected to the simulated sample SS1 and the counter electrode 302, respectively, and both lead wires are further connected to the AC impedance spectrum measuring device 310. Fill the bottomed cylindrical container with the electrolytic solution 304, so that only the resin layer S22 of each simulated sample SS1 is in contact with the electrolytic solution 304, and the connection portion of the lead wire in the strip S1 is not in contact with the electrolytic solution 304. Each simulated sample SS1 is immersed in the electrolytic solution 304, and the counter electrode 302 is immersed in the electrolytic solution 304. In this way, the electrochemical measurement cell 300 is constructed.
The above-described electrochemical measurement cell 300 is inserted into a thermostatic bath (not shown), the temperature of the electrolytic solution 304 is maintained at 60 ° C., and this immersion state is maintained for one week (1 W, 168 hours).
After one week, the AC impedance spectrum of each simulated sample SS1 is measured in the electrolyte solution 304, and the diffusion resistance value is calculated from the measured AC impedance spectrum.
The diffusion resistance value (Warburg impedance) is calculated using analysis by simulation using the equivalent circuit shown in FIG. When the diffusion resistance value is W, the equivalent circuit has a charge transfer resistance Rp in series with the diffusion resistance value W, a capacitance C in parallel with the diffusion resistance value W and the charge transfer resistance Rp, and a series connection with the parallel circuit. The electrolyte resistance Rs.

The measurement conditions for the AC impedance spectrum are: amplitude: 25 mV, measurement frequency range: 100 kHz to 100 mHz.
The measurement frequency (= measurement point of the AC impedance spectrum) is 10 points every time the frequency change amount is 10 times, and the AC impedance spectrum is measured by changing the frequency on a logarithmic scale. In this example, the number of AC impedance spectrum measurement points is 10 points from 100 kHz to 10 kHz, and 60 points in total. Each data of the AC impedance spectrum at each measurement frequency is reproduced by simulation using the above-described equivalent circuit, and each parameter of the equivalent circuit shown in FIG. 6 is estimated. The diffusion resistance value is calculated using the result of this simulation.
AC impedance spectrum can be automatically measured and analyzed using commercially available AC impedance spectrum measuring apparatus, AC impedance spectrum measuring software, and analysis software.
For example, VersaSTAT4-400 + VersaSTAT LC (Princeton Applied Research) can be used as the measurement device, VersaStudio (Princeton Applied Research) can be used as the measurement software, and Zview (Scribner Associates Inc.) can be used as the analysis software.

(Resin bond strength)
After immersing the entire simulated sample SS2 including the strip material S1 simulating the main body of the lead conductor shown in FIG. 7 and the resin film S22a and the resin film S22b respectively bonded to the front and back surfaces in an electrolytic solution for a predetermined time, The peel strength is measured as follows. The results are shown in Table 3.

As the electrolytic solution, the same one as used for measuring the diffusion resistance value (electrolytic solution manufactured by Kishida Chemical Co., Ltd.) is used. The temperature of the electrolytic solution is maintained at 80 ° C. using a thermostatic bath, and this immersion state is maintained for 1 week (1 W = 168 hours), 4 weeks (4 W), and 8 weeks (8 W).
After a predetermined immersion time has elapsed (here, after 1 W, after 4 W, or after 8 W), the simulated sample SS2 is taken out from the electrolyte, and one resin film S22a and the strip S1 are cut as shown in the left diagram of FIG. Then, it is divided into two (divided piece S1s, divided piece S1l, film piece la, film piece sa). The simulated sample SS2 is divided so that the length of the other divided piece S1l is sufficiently longer than the length of the one divided piece S1s.
The divided pieces S1l and divided pieces S1s that are divided are joined to the other resin film S22b. As shown in the right figure of FIG. 8, this other resin film S22b is folded back so that the short divided piece S1s is separated from the long divided piece S1l.
The long split piece S1l and the short split piece S1s are gripped by a commercially available tensile tester (not shown), and the split pieces S1l and the split pieces S1s are separated from each other as shown by the black arrows in the right diagram of FIG. Pull up and down in the right figure of 8). As the pulling force increases, the other resin film S22b is peeled off from the long divided piece S1l.
In this test, the maximum tensile force until the other resin film S22b is completely peeled from the long segment S1l is defined as peel strength (N), and the average value of n = 3 is shown in Table 3. It can be said that the greater the peel strength (N), the better the adhesion between the strip S1 and the resin film S22b.

As shown in Table 3, surface treatment is performed on a band material made of an Al—Mg—Si alloy having a specific composition containing Mg and Si in a specific range, in particular, chemical conversion treatment, boehmite treatment, alumite It can be seen that by performing one type of surface treatment selected from treatment and etching, or adjusting the treatment conditions, an aluminum alloy having excellent adhesion to the resin layer and a large diffusion resistance value can be obtained.

In this test, sample no. 2-11-No. 2-18 has a diffusion resistance value of 5 × 10 ⁵ Ω / cm ² or more, and many samples have a value of 10 × 10 ⁵ Ω / cm ² or more. Sample No. 2-11-No. As for 2-18, the peel strength after 8 W is 3N or more, many samples are 4N or more, and further, many samples are 5N or more, and it can be seen that the resin layer is difficult to peel over a long period of time. From this, it is considered that one of the reasons why the diffusion resistance value is large is that the resin layer is in close contact without being peeled off, and the contact area with the electrolytic solution in the strip of each sample can be reduced.

Sample No. with large diffusion resistance 2-11-No. When the 2-18 strip is used as the lead conductor of the power storage device, it is expected that the constituent components of the strip can be reduced from being eluted into the electrolyte, and the resistance to the electrolyte is excellent. Moreover, it can be said that the lead conductor excellent also in the tolerance with respect to such electrolyte solution is obtained by selecting an appropriate surface treatment method and process conditions.

Sample No. 2-11-No. The arithmetic average roughness Ra (JIS B 0601, 2001) of the surface-treated portion of the 2-18 strip was measured with a commercially available roughness measuring machine (evaluation length 3 μm, n = 9 average value). .1 μm or more and 0.5 μm or less. Thus, it is thought that it is excellent in adhesiveness with resin by roughening appropriately.

The present invention is not limited to these exemplifications, but is defined by the scope of the claims, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims. For example, the composition of the aluminum alloys of Test Examples 1 and 2, the width and thickness of the strip, the surface treatment method, the treatment conditions, the material and thickness of the coating resin layer, and the like can be changed as appropriate.

Claims (9)

1. A lead conductor used in a power storage device including a positive electrode, a negative electrode, an electrolytic solution, and a container for storing these,
   While containing 0.1 mass% or more and 1.2 mass% or less of Si,
   Mg is composed of an aluminum alloy containing Mg / Si in a range satisfying a mass ratio of 0.8 to 2.7 and less than 1.5% by mass,
   Tensile strength is 100 MPa or more and 220 MPa or less,
   A lead conductor having a conductivity of 50% IACS or more.
2. The lead conductor according to claim 1, wherein the 0.2% proof stress is 40 MPa or more.
3. The lead conductor according to claim 1, wherein the lead conductor has a thickness of 0.03 mm to 0.1 mm and a width of 1 mm to 10 mm.
4. 4. The lead conductor according to claim 1, wherein the diffusion resistance value is 5 × 10 ⁵ Ω · cm ⁻² or more.
5. The surface treatment portion according to any one of claims 1 to 4, further comprising a surface treatment portion on which at least a part selected from chemical conversion treatment, boehmite treatment, alumite treatment, and etching is applied to at least a part of the surface of the lead conductor. Lead conductor.
6. The aluminum alloy contains a total of one or more elements selected from Cu, Fe, Cr, Mn, Zn, Ni, Ag, and Zr in a range of 0.005% by mass to 1% by mass. 6. The lead conductor according to any one of items 5.
7. 7. The aluminum alloy according to claim 1, wherein the aluminum alloy contains at least one of Ti of 0.01% by mass to 0.05% by mass and B of 0.001% by mass to 0.008% by mass. The lead conductor according to item 1.
8. A coating resin layer bonded to a fixed region with the container in the lead conductor,
   The coating resin layer is a multilayer structure made of different resins,
   The lead conductor according to any one of claims 1 to 7, wherein a total thickness of the coating resin layer is 20 袖 m to 300 袖 m.
9. A power storage device comprising the lead conductor according to any one of claims 1 to 8.

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