Surface-treated metal sheet for battery

Abstract

Provided is a surface-treated metal sheet for a battery, the surface-treated metal sheet comprising: a metal base material; and a tin layer provided on at least one surface of the metal base material. A (MI (200) / MI (211)) ratio, which is the ratio of a crystal orientation index MI (200) of a (200) of the metal base material to a crystal orientation index MI (211) of a (211) of the metal base material, is 1.1 or more, and a crystal orientation index Sn (200) of a (200) of the tin layer is 2.95 or less.

Description

Surface-treated metal sheets for batteries

[0001] The present invention relates to a surface-treated metal sheet for batteries that has an effect of suppressing gas generation and is excellent in durability.

[0002] Nickel-cadmium batteries, nickel-metal hydride batteries, etc. are widely known as secondary batteries, so-called alkaline batteries, whose electrolyte is an alkaline aqueous solution. Among alkaline secondary batteries, air batteries and nickel-zinc batteries, which use nickel hydroxide or the like for the positive electrode, zinc or the like for the negative electrode active material, and an alkaline aqueous solution for the electrolyte, are being actively developed as next-generation batteries.

[0003] The advantages of nickel-zinc batteries include a high electromotive force and a high energy density for an aqueous battery, the low cost of zinc, the small amount of rare metals used, the fact that both nickel and zinc are recyclable metals, and the use of an aqueous electrolyte, which makes them safer than lithium-ion batteries.

[0004] On the other hand, one of the challenges in practical application of zinc-air batteries and nickel-zinc batteries as secondary batteries is the problem of hydrogen gas generation (hereinafter also referred to as gas generation) during charging and discharging (including natural discharge). If hydrogen gas generation occurs and the amount generated becomes too large, it can cause a decrease in battery performance, an increase in internal pressure, and lead to battery leakage. These problems can occur particularly noticeably in batteries in which zinc is involved in the battery reaction.

[0005] It has been known that the above-mentioned problem of hydrogen gas generation can be solved by applying a material with a high hydrogen overvoltage to the negative electrode current collector. For example, Patent Document 1 discloses a nickel-zinc battery in which the negative electrode current collector is made of a tin-plated metal material with a high hydrogen overvoltage.

[0006] Japanese Patent Application Laid-Open No. 2019-139986

[0007] However, as described in Patent Document 1, when the potassium hydroxide concentration in the electrolyte is set to a high concentration of 20 wt % or more in order for the alkaline secondary battery to exhibit sufficient battery performance, the technology described in Patent Document 1 has the problem that gas generation may not be sufficiently prevented depending on the state of tin plating. Furthermore, in the above-mentioned high-concentration electrolyte environment, repeated charge and discharge can dissolve tin, exposing part of the tin-plated metal material to the electrolyte and increasing the risk of gas generation, resulting in a problem of low durability.

[0008] The problem to be solved by the present invention is to provide a surface-treated metal sheet for batteries that is effective in suppressing gas generation during charging and discharging of alkaline secondary batteries in a high-concentration electrolyte environment as described above, and that has excellent durability.

[0009] As a result of intensive research into achieving the above-mentioned object, the inventors have found that the above-mentioned object can be achieved by a surface-treated metal sheet for batteries, which comprises a metal substrate and a tin layer provided on at least one surface of the metal substrate, and in which the crystal orientation indexes of the metal substrate and the tin layer are controlled, and have thus completed the present invention.

[0010] [1] According to a first aspect of the present invention, there is provided a surface-treated metal sheet for batteries, comprising a metal substrate and a tin layer provided on at least one surface of the metal substrate, wherein the ratio (MI(200) / MI(211)) of the crystal orientation index MI(200) of the (200) plane of the metal substrate to the crystal orientation index MI(211) of the (211) plane of the metal substrate is 1.1 or more, and the crystal orientation index Sn(200) of the (200) plane of the tin layer is 2.95 or less.

[0011] [2] According to a second aspect of the present invention, there is provided the surface-treated metal sheet for batteries according to the first aspect, wherein the metal substrate is an iron-based metal substrate.

[0012] [3] According to a third aspect of the present invention, there is provided the surface-treated metal sheet for batteries according to the second aspect, in which the iron-based metal substrate is a steel plate.

[0013] [4] According to a fourth aspect of the present invention, there is provided the surface-treated metal sheet for batteries according to the third aspect, wherein the steel sheet is a low-carbon steel or an ultra-low-carbon steel.

[0014] [5] According to a fifth aspect of the present invention, there is provided the surface-treated metal sheet for a battery according to any one of the first to fourth aspects, wherein the metal substrate has a thickness of 0.01 mm to 1.2 mm.

[0015] [6] According to aspect 6 of the present invention, the tin coating amount in the tin layer is 1.0 g / m ２ Above, 35.0g / m ２ There is provided a surface-treated metal sheet for a battery according to any one of Aspects 1 to 5 below.

[0016] [7] According to a seventh aspect of the present invention, there is provided the surface-treated metal sheet for a battery according to any one of the first to sixth aspects, wherein the tin layer has a thickness of 0.15 μm or more and 5.00 μm or less.

[0017] [8] According to aspect 8 of the present invention, the ratio of the crystal orientation index Sn(200) of the (200) plane of the tin layer to the thickness (μm) of the tin layer (Sn(200) / thickness (μm) of the tin layer) is 6.00 or less. The surface-treated metal sheet for a battery according to any one of aspects 1 to 7.

[0018] [9] A ninth aspect of the present invention provides the surface-treated metal sheet for a battery according to any one of the first to eighth aspects, wherein the ratio of the crystal orientation index Sn(200) of the (200) plane of the tin layer to the thickness (μm) of the tin layer (Sn(200) / thickness (μm) of tin layer) is 3.00 or less.

[0019] According to the present invention, it is possible to provide a surface-treated metal sheet for batteries that has an effect of suppressing gas generation and is excellent in durability.

[0020] FIG. 1 is a cross-sectional view of a surface-treated metal sheet for batteries according to an embodiment of the present invention.

[0021] The surface-treated metal sheet for batteries of the present invention is a surface-treated metal sheet used in batteries, such as a current collector for a negative electrode, a battery tab / lead material, and a battery container for housing a battery's power generating element. Examples of batteries include, but are not limited to, aqueous batteries using alkaline electrolytes, such as nickel-cadmium batteries, nickel-metal hydride batteries, air-zinc batteries, and nickel-zinc batteries, as well as non-aqueous batteries such as lithium-ion batteries. The surface-treated metal sheet for batteries of the present invention is suitable for aqueous batteries, particularly aqueous batteries in which zinc is involved in the battery reaction (e.g., nickel-zinc batteries), as a current collector or battery container. The present invention can be applied to both primary and secondary aqueous batteries. The surface-treated metal sheet for batteries of this embodiment is particularly suitable for alkaline secondary batteries, which are used in high-concentration electrolyte environments (e.g., electrolytes with a potassium hydroxide concentration of 20 wt % or more).

[0022] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0023] 1 is a cross-sectional view of a surface-treated metal sheet for batteries 10 according to an embodiment of the present invention. As shown in FIG. 1, the surface-treated metal sheet for batteries 10 according to this embodiment includes a metal substrate 20 and tin layers 30 provided on both sides of the metal substrate 20.

[0024] While FIG. 1 illustrates an example in which a tin layer 30 is formed on both sides of the metal substrate 20, the configuration of the surface-treated metal sheet 10 for batteries is not particularly limited thereto. In the surface-treated metal sheet 10 for batteries, the tin layer 30 may be formed on at least one side of the metal substrate 20. Furthermore, in the present embodiment, the tin layer 30 may be formed on a surface where gas generation suppression is required. For example, when the surface-treated metal sheet 10 for batteries according to this embodiment is used as a negative electrode current collector (for example, when used as a negative electrode current collector for a nickel-zinc battery), a lead material, or a tab material, the tin layer 30 may be formed on both sides of the metal substrate 20. Furthermore, when the surface-treated metal sheet 10 for batteries according to this embodiment is used as a battery container such as a container or an electrode can, the tin layer 30 may be formed on the surface of the metal substrate 20 that faces the inner surface of the battery. The surface that faces the outer surface of the battery is not particularly limited, and may either have the tin layer 30 formed thereon or not have the tin layer 30 formed thereon.

[0025] <Metal substrate 20> In the metal substrate 20, the ratio (MI(200) / MI(211)) of the crystal orientation index MI(200) of the (200) plane of the metal substrate 20 to the crystal orientation index MI(211) of the (211) plane satisfies 1.1 or more. Since the ratio (MI(200) / MI(211)) of the crystal orientation index MI(200) of the (200) plane of the metal substrate 20 to the crystal orientation index MI(211) of the (211) plane of the metal substrate 20 is 1.1 or more, the surface-treated metal sheet 10 for batteries in this embodiment has excellent durability when used for batteries. In other words, the surface-treated metal sheet 10 for batteries in this embodiment can suppress gas generation over a long period of time. In this embodiment, in order to further improve durability, the crystal orientation index ratio (MI(200) / MI(211)) is preferably 1.3 or more, more preferably 1.5 or more. The upper limit of the ratio of the crystal orientation index of the (200) plane of the metal substrate to the crystal orientation index of the (211) plane (MI(200) / MI(211)) is not particularly limited, but is usually 5.0 or less.

[0026] The crystal orientation index MI(200) of the (200) plane and the crystal orientation index MI(211) of the (211) plane of the metal base 20 can be determined as follows. Note that the following description will be given assuming that low carbon steel or ultra-low carbon steel is used as the metal base 20.

[0027] First, the crystal orientation index MI(200) of the (200) plane of the metal substrate 20 is determined by measuring the diffraction intensity of each crystal plane on the surface of the metal substrate 20 using an X-ray diffractometer with a CuKα radiation source, and then using the obtained diffraction intensity of iron and the diffraction intensity of a standard iron powder, by the method of Willson and Rogers (described in "K.S. Willson and J.A. Rogers; Tech. Proceeding Amer. Electroplaters Soc., 51, 92 (1964)"). It can be calculated based on the following formula (1). Note that, as the diffraction intensity data, data on the (110), (200), and (211) planes, which are said to appear within a diffraction angle (2θ) range of 30 to 90° when the X-ray source is CuKα, are used.

[0028] The crystal orientation index MI(200) of the (200) plane of the metal base 20 can be calculated based on the following formula (1): MI(200)=IF(200) / IFR(200) (1)

[0029] IF(200) and IFR(200) in the above formula (1) can be calculated based on the following formulas (2) and (3), respectively: IF(200) = I(200) / [I(110) + I(200) + I(211)] (2) IFR(200) = IR(200) / [IR(110) + IR(200) + IR(211)] (3)

[0030] In the above formula (1), IF(hkl) (h, k, l are each an integer) represents the X-ray diffraction intensity ratio from the (hkl) plane, and IFR(hkl) represents the X-ray diffraction intensity ratio from the (hkl) plane of standard iron powder. In the above formula (2), I(hkl) represents the X-ray diffraction intensity from the (hkl) plane. In the above formula (3), IR(hkl) represents the X-ray diffraction intensity from the (hkl) plane of standard iron powder as described in 03-065-4899 of the ICDD PDF-2 2014 database. The same applies to the following formulas (4) to (6) described later.

[0031] The crystal orientation index MI(211) of the (211) plane of the metal base 20 can be calculated based on the following formula (4) using the measurement results of the diffraction intensity of each crystal plane on the surface of the metal base 20 by an X-ray diffractometer: MI(211)=IF(211) / IFR(211) (4)

[0032] IF(211) and IFR(211) in the above formula (4) can be calculated based on the following formulas (5) and (6), respectively: IF(211) = I(211) / [I(110) + I(200) + I(211)] (5) IFR(211) = IR(211) / [IR(110) + IR(200) + IR(211)] (6)

[0033] By determining the crystal orientation indexes MI(200) and MI(211) of the (200) and (211) planes of the metal base 20 in the manner described above, the ratio (MI(200) / MI(211)) of the crystal orientation index MI(200) of the (200) plane to the crystal orientation index MI(211) of the (211) plane can be determined.

[0034] The metal substrate 20 is not particularly limited in type as long as the ratio (MI(200) / MI(211)) of the crystal orientation index MI(200) of the (200) plane to the crystal orientation index MI(211) of the (211) plane is 1.1 or greater. For example, a metal plate based on one selected from iron, copper, and nickel is preferably used. Specifically, a steel plate, a copper plate, a nickel plate, or the like can be used as the metal substrate 20. Among these, iron is preferred as the metal type, from the viewpoint of easily and suitably controlling the crystal orientation index MI(200) of the (200) plane and the crystal orientation index MI(211) of the (211) plane of the metal substrate 20. Using iron as the metal type is preferred because it makes it easier to control the crystal orientation indexes of the (200) plane and the (211) plane, thereby making it possible to suitably suppress defects that occur when forming the tin layer 30 described below, and also enabling the strength of the metal substrate 20 to be suitably controlled.

[0035] When the metal substrate 20 is an iron-based metal substrate, a steel plate is preferably used. Examples of steel plates that can be used include low-carbon steel (carbon content: 0.01 to 0.15 wt%), ultra-low-carbon steel (carbon content: less than 0.01 wt%), and non-aging ultra-low-carbon steel obtained by adding Ti, Nb, or the like to ultra-low-carbon steel. Examples of metal substrates that can be used include electrolytic foils made of a pure metal selected from iron, copper, and nickel (electrolytic foils containing 99.9 wt% or more of a metal selected from iron, copper, and nickel), and electrolytic foils made of an alloy containing two or more metals selected from iron, copper, and nickel. When the surface-treated metal sheet 10 for batteries according to this embodiment is used as a negative electrode current collector, the metal substrate 20 may be a perforated plate or foil having through-holes.

[0036] When a metal plate based on a metal other than iron, such as copper or nickel, is used as the metal substrate 20, the crystal orientation index of each plane can be determined by the above method, similar to when a steel plate is used as the metal substrate 20. For example, when a nickel plate is used as the metal substrate 20, the crystal orientation index of each plane can be determined based on the above formulas (1) to (6) using data on the X-ray diffraction intensity of a standard nickel powder and measurement results of the diffraction intensity of each crystal plane on the surface of the metal substrate 20 obtained by an X-ray diffractometer.

[0037] The thickness of the metal substrate 20 is not particularly limited, but is preferably 0.005 to 2.0 mm, more preferably 0.01 to 1.0 mm. For example, when used as a current collector, it is preferably 0.01 to 0.3 mm, more preferably 0.01 to 0.2 mm, and particularly preferably 0.01 to 0.1 mm. When used as a battery container or battery tab / lead material, it is preferably 0.1 to 1.2 mm, more preferably 0.1 to 1.0 mm, and particularly preferably 0.15 to 0.5 mm. As described below, the metal substrate 20 can be prepared by cold-rolling a metal plate, and the thickness of the metal substrate 20 after cold-rolling is preferably within the above range. The thickness of the metal substrate 20 is preferably measured by cross-sectional observation using an optical microscope or a scanning electron microscope (SEM). Furthermore, thickness measurement using a micrometer or the like can be applied before surface treatment, i.e., before the formation of the tin layer 30 described below.

[0038] In the metal substrate 20, it is sufficient that the ratio (MI(200) / MI(211)) of the crystal orientation index MI(200) of the (200) plane to the crystal orientation index MI(211) of the (211) plane measured on the surface on which the tin layer 30 is formed is 1.1 or more.

[0039] <Tin layer 30> As shown in Fig. 1 , the surface-treated metal sheet for batteries 10 of this embodiment includes a tin layer 30 formed on the surface of the metal substrate 20. The tin layer 30 can be formed by tin plating the metal substrate 20.

[0040] The tin layer 30 has a crystal orientation index Sn(200) of the (200) plane determined by X-ray diffraction measurement of 2.95 or less, preferably 2.80 or less, more preferably 2.50 or less, and particularly preferably 2.00 or less. The lower limit of the crystal orientation index Sn(200) of the (200) plane of the tin layer 30 is not particularly limited, but is usually 0.01 or more. The above-mentioned Sn(200) represents the crystal orientation index of the (200) plane of the tin layer 30.

[0041] The crystal orientation index Sn(200) of the (200) plane of the tin layer 30 can be determined in the same manner as the method for determining the crystal orientation index of the metal substrate 20 described above. That is, the diffraction intensity of each crystal plane on the surface of the tin layer 30 is measured using an X-ray diffractometer with a CuKα radiation source, and then the obtained diffraction peaks of tin and the diffraction peaks of standard tin powder are used to calculate the crystal orientation index Sn(200) by the method of Willson and Rogers. The diffraction intensity data used is data on the (200) plane, (101), (220), (211), (301), (112), (400), (321), (420), (411), (312), and (501) planes, which are considered to appear within a diffraction angle (2θ) range of 30 to 90° when the X-ray source is CuKα. The crystal orientation index Sn(200) can be calculated by the Wilson and Rogers method based on the following formula (7): Sn(200)=IF(200) / IFR(200) (7)

[0042] In the above formula (7), IF(200) can be calculated by the following formula (8): IF(200) = I(200) / [I(200) + I(101) + I(220) + I(211) + I(301) + I(112) + I(400) + I(321) + I(420) + I(411) + I(312) + I(501)] (8)

[0043] In the above formula (7), IFR(200) can be calculated by the following formula (9): IFR(200) = IR(200) / [IR(200) + IR(101) + IR(220) + IR(211) + IR(301) + IR(112) + IR(400) + IR(321) + IR(420) + IR(411) + IR(312) + IR(501)] (9)

[0044] In the above formula (7), IF(200) represents the X-ray diffraction intensity ratio from the (200) plane, in the above formula (8), I(hkl) represents the X-ray diffraction intensity from the (hkl) plane, and in the above formula (9), IR(hkl) represents the X-ray diffraction intensity from the (hkl) plane described in 00-004-0673 of the ICDD PDF-2 2014 database for standard tin powder.

[0045] The tin coverage in the tin layer 30 is preferably 1.0 g / m ２ More preferably, it is 2.0 g / m or more. ２ More preferably, 3.0 g / m ２ More preferably, 5.0 g / m ２ The upper limit of the amount of tin deposited in the tin layer 30 is not particularly limited, but is preferably 35.0 g / m ２ More preferably, 25.0 g / m or less. ２ More preferably 20.0 g / m or less ２ Particularly preferably 15.0 g / m or less ２ By setting the tin deposition amount in the tin layer 30 within the above range, gas generation during charge and discharge can be effectively suppressed. In particular, when the tin deposition amount in the tin layer 30 is 5.0 g / m or less, ２ By controlling the tin content within the above range, it is possible to suitably control the crystal orientation index Sn(200) of the (200) plane of the tin layer 30. This makes it possible to more effectively suppress gas generation, and even if tin dissolution into the electrolyte occurs due to repeated charge and discharge, it is possible to suitably control the dissolution of tin. The tin deposition amount can be determined by subjecting the surface-treated metal sheet for batteries 10 to X-ray fluorescence measurement or ICP emission spectroscopy analysis. The above tin deposition amount represents the deposition amount on one side of the metal substrate 20.

[0046] The thickness of the tin layer 30 is preferably 0.15 μm or more, more preferably 0.30 μm or more, even more preferably 0.50 μm or more, and particularly preferably 1.00 μm or more. The upper limit of the thickness of the tin layer 30 is not particularly limited, but is preferably 5.00 μm or less, more preferably 3.00 μm or less, even more preferably 2.50 μm or less, and particularly preferably 2.00 μm or less. By setting the thickness of the tin layer 30 within the above range, gas generation during charge and discharge can be effectively suppressed while improving durability. In particular, by setting the thickness of the tin layer 30 to 1.00 μm or more, the gas generation suppression effect and durability can be further improved. On the other hand, if the thickness of the tin layer 30 is below the lower limit of the above range, the crystal orientation index of the tin layer 30 cannot be appropriately controlled, and gas generation tends to become significant. The thickness of the tin layer 30 is determined by multiplying the tin deposition amount determined by the above method by the density of tin (g / cm ３ ) and converting it into a thickness (dividing the amount of tin deposition by the density), but the method for determining the thickness of the tin layer 30 is not limited to this. Other methods for determining the thickness of the tin layer 30 that can be used include, for example, thickness measurement by cross-sectional observation with a scanning electron microscope (SEM), thickness measurement with a transmission electron microscope (TEM), and measurement with a high-frequency glow discharge optical emission spectrometer.

[0047] In this embodiment, in order to further enhance the gas generation suppression effect, it is preferable that the ratio of the crystal orientation index Sn(200) of the (200) plane of the tin layer to the thickness (μm) of the tin layer (Sn(200) / thickness of tin layer (μm)) is 6.00 or less. The inventors have found that with regard to the gas generation suppression effect of the surface-treated metal sheet for batteries 10, the thickness of the tin layer 30 and the crystal orientation index Sn(200) of the tin layer 30 are closely related. That is, the inventors have found that the gas generation suppression effect can be more suitably enhanced by controlling the crystal orientation index Sn(200) to satisfy the above range relative to the thickness of the tin layer 30. In order to more significantly enhance the gas generation suppression effect, the ratio of the crystal orientation index Sn(200) of the (200) plane of the tin layer to the thickness (μm) of the tin layer (Sn(200) / thickness (μm) of the tin layer) is more preferably 4.00 or less, and particularly preferably 3.00 or less. The lower limit of the ratio of the crystal orientation index Sn(200) of the (200) plane of the tin layer to the thickness (μm) of the tin layer (Sn(200) / thickness (μm) of the tin layer) is not particularly limited, but is usually 0.01 or more.

[0048] In the surface-treated metal sheet for batteries 10 of this embodiment, the ratio of the crystal orientation index MI(200) of the (200) plane of the metal substrate 20 to the crystal orientation index MI(211) of the (211) plane of the metal substrate 20 (MI(200) / MI(211)) is 1.1 or more, and the crystal orientation index Sn(200) of the (200) plane of the tin layer 30 is 2.95 or less. The reason why such a configuration is preferable is as follows.

[0049] As mentioned above, one of the challenges facing the practical application of alkaline secondary batteries is the problem of hydrogen gas generation. Hydrogen gas is generated when the reaction conditions for hydrogen gas generation are met under conditions where a chemical reaction other than the battery reaction (self-discharge) occurs due to the formation of a local battery between dissimilar metals inside the battery. For example, in nickel-zinc batteries, zinc precipitates in the form of zinc or zinc oxide during charging and dissolves during discharge. However, zinc has one of the lowest potentials among metals used in aqueous batteries, so when a local battery state is formed between zinc and other metals used in the battery, the discharge rate is high, making it easy to meet the conditions for hydrogen gas generation.

[0050] Excessive hydrogen gas generation can lead to reduced battery performance and leakage problems. Specifically, when hydrogen gas generation occurs due to self-discharge, electrons that should contribute to the battery reaction are consumed by hydrogen gas generation, leading to reduced battery performance. The more hydrogen gas generated, the more the battery performance deteriorates. Furthermore, leakage may occur due to increased internal pressure, leading to reduced safety. Note that self-discharge here includes both side reactions during charging and discharging (chemical reactions including the hydrogen gas generation process) and chemical reactions that occur outside of charging and discharging, i.e., when the battery is left standing.

[0051] To avoid such problems as deterioration of battery performance and leakage, it is necessary to minimize the amount of hydrogen gas generated. In particular, the current collector material is a component that is more likely to generate hydrogen gas and is also more likely to self-discharge because zinc and other elements in the electrolyte are deposited on its surface and come into direct contact with it.

[0052] To address this issue, one method for suppressing hydrogen gas generation is known to be the use of a material with a high hydrogen overvoltage. In this embodiment, tin (Sn) in the tin layer is considered to be a material with a high hydrogen overvoltage. However, the inventors have confirmed that even when tin with a high hydrogen overvoltage is used, the effectiveness of suppressing hydrogen gas generation varies depending on the crystal orientation state of the tin layer. Furthermore, the inventors have found that by controlling the crystal orientation index Sn(200) of the (200) plane of the tin layer 30 to 2.95 or less, it is possible to suppress defects (hereinafter also referred to as plating defects) with locally low tin deposition on the surface of the tin layer 30, thereby suppressing gas generation from the surface-treated metal sheet for batteries 10.

[0053] Furthermore, the present inventors have found that even in a battery surface-treated metal sheet in which the surface of a metal substrate appears to be coated with a tin layer by tin plating, if the surface of the tin layer dissolves due to repeated charge / discharge in a highly concentrated electrolyte environment (hereinafter also referred to as in the electrolyte), a portion of the metal substrate may be exposed to the surface and gas may be generated. The reason for this problem is thought to be as follows. That is, even if there are no apparent defects on the outermost surface of the tin layer and the metal substrate appears to be sufficiently coated with the tin layer, there may be localized defects in the tin layer where the amount of tin deposited is low. When a battery surface-treated metal sheet containing such defects is used, repeated long-term charge / discharge accelerates tin dissolution due to the defects, exposing the metal substrate to the surface and exposing it to the electrolyte. Therefore, when a metal with a low hydrogen overvoltage (e.g., iron, copper, or nickel) is used as the metal substrate, the corrosion current is thought to increase, resulting in gas generation.

[0054] In response to these problems, the present inventors have discovered that by setting the ratio of the crystal orientation index MI(200) of the (200) plane of the metal substrate 20 to the crystal orientation index MI(211) of the (211) plane of the metal substrate 20 (MI(200) / MI(211)) to be 1.1 or greater, gas generation can be suppressed over a long period of time in the surface-treated metal sheet for batteries 10, resulting in excellent durability. The reason for this is unclear, but the following is thought to be the case. That is, the state of tin electrodeposition on the metal substrate 20 varies depending on the crystal plane of the metal substrate 20. By controlling the crystal plane of the metal substrate 20 so that the ratio of the crystal orientation index MI(200) (MI(200) / MI(211)) is 1.1 or greater, it is possible to improve the uniformity of electrodeposition when tin is plated on the metal substrate 20 (at the time of initial electrodeposition), thereby suppressing defects in the tin layer 30. Therefore, in the surface-treated metal plate 10 for batteries in this embodiment, even if tin dissolution occurs on the surface of the tin layer 30 due to repeated charging and discharging, it is possible to prevent the metal substrate 20 from being exposed to the surface, and it is therefore thought that the durability of the battery can be improved.

[0055] As a result of extensive research into materials that have the above-mentioned gas generation suppression effect and excellent durability, the inventors have found that by controlling the crystal orientation index ratio (MI(200) / MI(211)) of the metal substrate 20 to be 1.1 or more and the crystal orientation index Sn(200) of the tin layer 30 to be 2.95 or less, defects in the tin layer 30 are suppressed overall, thereby suppressing gas generation and achieving excellent durability.

[0056] On the other hand, when the ratio of the crystal orientation indices (MI(200) / MI(211)) of the metal base 20 is less than 1.1 or the crystal orientation index Sn(200) of the tin layer 30 is more than 2.95, defects are formed in the tin layer 30, and the defects promote dissolution of tin during repeated charge and discharge, exposing part of the metal base 20 to the electrolyte, which tends to make it easier for gas to be generated during charge and discharge. In particular, when the ratio of the crystal orientation indices (MI(200) / MI(211)) is less than 1.1, the initial plating (particularly when the tin deposition amount is 2.0 g / m ２ The inventors have confirmed that this causes uneven electrodeposition at a surface roughness of less than 100 nm (less than 100 nm), resulting in increased surface irregularities in the tin layer 30 at the initial stage of plating. Since plating has the property of easily concentrating on protruding portions, it is believed that continuing plating on a surface with many irregularities further deteriorates the uniformity of plating, and defects in the tin layer 30 where the amount of tin deposition is low are formed locally.

[0057] <Method for manufacturing surface-treated metal sheet 10 for batteries> The surface-treated metal sheet 10 for batteries according to this embodiment can be manufactured by tin-plating both surfaces of a metal substrate 20 to form a tin layer 30. In this embodiment, the tin layer 30 is formed on both surfaces of the metal substrate 20, but the present invention is not particularly limited to this embodiment, and it is sufficient that the tin layer 30 is formed on at least one surface of the metal substrate 20.

[0058] First, a metal substrate 20 is prepared in which the ratio (MI(200) / MI(211)) of the crystal orientation index MI(200) of the (200) plane of the metal substrate 20 to the crystal orientation index MI(211) of the (211) plane of the metal substrate 20 is controlled to be 1.1 or more. The method for preparing such a metal substrate 20 is not particularly limited, but examples thereof include a method of cold-rolling a metal plate (first method), a method of cold-rolling a metal plate followed by continuous annealing (second method), and a method of cold-rolling a metal plate followed by continuous annealing and then cold-rolling again (hereinafter also referred to as re-rolling) (third method). As described above, a metal plate based on one selected from iron, copper, and nickel is preferably used as the metal plate, and is preferably an iron-based metal plate, more preferably a steel plate, and particularly preferably a steel plate made of low-carbon steel or ultra-low-carbon steel.

[0059] In the first method, the metal substrate 20 is prepared by cold rolling a metal plate (first cold rolling). The reduction (%) in cold rolling the metal plate is preferably 80% to 99%, more preferably 83% to 99%, and particularly preferably 85% to 95%, from the viewpoint of easily controlling the crystal orientation index of the metal substrate 20. If the reduction exceeds the lower or upper limit of the above-mentioned reduction, it is difficult to control the crystal orientation index of the metal substrate 20, which is not preferable. The reduction (%) refers to the reduction rate (%) of the thickness of the metal plate before and after cold rolling, and can be determined by dividing the amount of change in the thickness of the metal plate before and after cold rolling by the thickness of the metal plate before cold rolling.

[0060] In the second method, a metal substrate 20 is prepared by cold rolling a metal plate and then performing continuous annealing. The cold rolling reduction (%) may be the same as that in the first method described above. Heat treatment conditions for continuous annealing are preferably a heat treatment temperature of 550°C or higher and 850°C or lower, and a heat treatment time of 10 seconds or higher and 5 minutes or lower. By using these heat treatment conditions, the crystal orientation index ratio (MI(200) / MI(211)) of the metal substrate 20 can be easily and suitably controlled, and the metal substrate can be appropriately softened. To further soften the metal substrate 20, it is more preferable to set the heat treatment temperature to 650°C or higher and 850°C or lower, and the heat treatment time to 10 seconds or higher and 5 minutes or lower. After the heat treatment, temper rolling with a reduction (%) of more than 0% but less than 10% may be performed, as long as the crystal orientation index ratio (MI(200) / MI(211)) is in a range satisfying 1.1 or higher.

[0061] Heat treatment temperatures exceeding 850°C or heat treatment times exceeding 5 minutes are not preferred because it becomes difficult to control the crystal orientation index of the metal substrate 20. In particular, heat treatment by box annealing requires a long period of time, making it extremely difficult to control the crystal orientation index of the metal substrate 20, and there is also a risk of the strength of the metal substrate 20 being extremely reduced, which is not preferred.

[0062] In the third method, the metal substrate 20 is prepared by cold-rolling a metal sheet, followed by continuous annealing and re-rolling (secondary cold rolling). The conditions for the first cold rolling (first cold rolling) and continuous annealing may be the same as those for the first and second methods. The reduction ratio (%) in the re-rolling of the metal sheet is preferably 10% to 90%, more preferably 10% to 85%, and even more preferably 10% to 80%. In particular, by using the above reduction ratio (%), the thickness of the metal substrate 20 can be reduced, the crystal orientation indices MI(200) and MI(211) can be suitably controlled, and the strength of the metal substrate 20 can be increased. This makes the surface-treated metal sheet 10 for batteries more suitable for use as a current collector. In order to further increase the strength of the metal base material 20, the rolling reduction (%) is more preferably 45% or more and 85% or less, even more preferably 45% or more and 80% or less, and particularly preferably 50% or more and 80% or less.

[0063] If the reduction rate (%) in the re-rolling exceeds 90%, it is difficult to control the crystal orientation index of the metal substrate 20, and the elongation of the metal substrate 20 tends to decrease and become too hard. For this reason, cracks may occur in the surface-treated metal sheet for batteries 10 depending on the processing conditions when used as a battery, or cracks may occur due to vibration or thermal expansion when used as a battery component. Therefore, it is not preferable for the reduction rate (%) in the re-rolling to exceed 90%.

[0064] In the third method, after the first cold rolling, at least one of continuous annealing and re-rolling may be performed two or more times. In this case, it is preferable to alternately perform continuous annealing and re-rolling. When performing at least two or more steps of continuous annealing or re-rolling, the heat treatment conditions for continuous annealing or the reduction rate (%) conditions for re-rolling in the final step of obtaining the metal substrate 20 may be the same as those in the second method described above. For example, when performing two continuous annealing steps, the heat treatment conditions for the continuous annealing in the second step may be a heat treatment temperature of preferably 550°C or higher and 850°C or lower, and a heat treatment time of preferably 10 seconds or higher and 5 minutes or lower. Furthermore, when performing two re-rolling steps, the conditions for the re-rolling (third cold rolling) in the second step may be preferably 10% or higher and 90% or lower, more preferably 10% or higher and 85% or lower, and even more preferably 10% or higher and 80% or lower. When two or more continuous annealing steps are performed, the heat treatment conditions in the other continuous annealing steps except for the final continuous annealing step are not particularly limited, but it is preferable that the heat treatment temperature is 550° C. or higher and 850° C. or lower, and the heat treatment time is 10 seconds or higher and 5 minutes or lower. Furthermore, when two or more re-rolling steps are performed, the rolling ratio (%) in the other re-rolling steps except for the final re-rolling step is preferably 10% or higher and 90% or lower, more preferably 10% or higher and 85% or lower, and even more preferably 10% or higher and 80% or lower.

[0065] As a third method, continuous annealing and re-rolling may each be performed two or more times. In this case, it is preferable to alternately perform continuous annealing and re-rolling twice. When continuous annealing and re-rolling are each performed two or more times, as described above, the heat treatment conditions for continuous annealing and the reduction rate (%) conditions for re-rolling in the final step of obtaining the metal substrate 20 may be the same as those in the second method described above. For example, as the heat treatment conditions for continuous annealing in the second step, the heat treatment temperature may be preferably 550°C or higher and 850°C or lower, and the heat treatment time may be preferably 10 seconds or higher and 5 minutes or lower. The conditions for re-rolling (third cold rolling) in the second step may be preferably 10% or higher and 90% or lower, more preferably 10% or higher and 85% or lower, and even more preferably 10% or higher and 80% or lower. When two or more continuous annealing steps are performed, the heat treatment conditions in the other continuous annealing steps except for the final continuous annealing step are not particularly limited, but it is preferable that the heat treatment temperature is 550° C. or higher and 850° C. or lower, and the heat treatment time is 10 seconds or higher and 5 minutes or lower. Furthermore, when two or more re-rolling steps are performed, the rolling ratio (%) in the other re-rolling steps except for the final re-rolling step is preferably 10% or higher and 90% or lower, more preferably 10% or higher and 85% or lower, and even more preferably 10% or higher and 80% or lower.

[0066] As a third method, when the metal substrate 20 is obtained by performing continuous annealing, re-rolling (secondary cold rolling), continuous annealing, and re-rolling (tertiary cold rolling) in this order after primary cold rolling, it is preferable to perform each step under the following conditions. That is, the rolling reduction (%) in the primary cold rolling is preferably 80% to 99%, more preferably 83% to 99%, and even more preferably 85% to 95%. In the continuous annealing after the primary cold rolling, it is preferable to set the heat treatment temperature to 550°C to 850°C and the heat treatment time to 10 seconds to 5 minutes. In the re-rolling (secondary cold rolling), the rolling reduction (%) is preferably 10% to 90%, more preferably 20% to 80%, and even more preferably 30% to 60%. In the continuous annealing after the secondary cold rolling, it is preferable to set the heat treatment temperature to 550°C to 850°C and the heat treatment time to 10 seconds to 5 minutes. The rolling reduction (%) in the re-rolling (tertiary cold rolling) is preferably 10% or more and 90% or less, more preferably 30% or more and 85% or less, and particularly preferably 50% or more and 80% or less.

[0067] The heat treatment conditions for continuous annealing up to the final step and the reduction rate (%) conditions for re-rolling may be appropriately selected depending on the properties required for the battery application (for example, the strength and thickness of the metal substrate 20). For example, when either continuous annealing or re-rolling is performed in two steps, or when continuous annealing and re-rolling are each performed in two steps, the heat treatment conditions for continuous annealing in the first step and the reduction rate (%) conditions for re-rolling (secondary cold rolling) may be adjusted so that the strength and thickness of the metal substrate 20 finally obtained are within a preferred range. Preferably, the continuous annealing and re-rolling in the first step may be performed under the same conditions as in the second method described above.

[0068] The first to third methods may be selected as appropriate depending on the properties (such as thickness and strength) required for the battery application.

[0069] Next, the surface of the metal substrate 20 is tin-plated to form a tin layer 30, thereby obtaining a surface-treated metal sheet for batteries 10. The method for forming the tin layer 30 is not particularly limited as long as the crystal orientation index Sn(200) of the (200) plane of the tin layer 30 is controlled to be 2.95 or less. Examples of the method include adding an additive to a tin plating bath used to form the tin layer 30, or adjusting and controlling the current density and treatment time of the tin plating.

[0070] The tin plating bath used to form the tin layer 30 may be a ferrostane bath, an MSA bath, a halogen bath, a sulfuric acid bath, or the like, which further contains additives. Of these, a sulfuric acid bath having a bath composition of 10 to 60 g / L of tin ions and 25 to 110 mL / L of sulfuric acid and further containing additives is preferred. Furthermore, a bath composition of 10 to 60 g / L of tin ions and 25 to 60 mL / L of sulfuric acid and further containing the above-mentioned additives is particularly preferred.

[0071] Examples of additives to be added to the tin plating bath include ethoxylated naphthol and ethoxylated naphthol sulfonic acid. Commercially available products include Technistan TP Additive manufactured by Technic Japan Co., Ltd. and UTB230R manufactured by Ishihara Chemical Co., Ltd. The amount of additive added to the tin plating bath is preferably 5 to 100 mL / L, more preferably 10 to 100 mL / L, and even more preferably 15 to 50 mL / L.

[0072] Among the plating conditions for forming the tin layer 30, the current density is preferably 1.0 to 30.0 A / dm ２ and more preferably 2.0 to 15.0 A / dm ２ , more preferably 4.0 to 15.0 A / dm ２ The temperature of the plating bath is preferably 25 to 60° C., more preferably 35 to 55° C. The pH of the plating bath is preferably 1.0 or less.

[0073] Among the plating conditions for forming the tin layer 30, the treatment time may be controlled so as to fall within the above-mentioned range of the tin coating amount while appropriately selecting the above-mentioned plating conditions. That is, the tin coating amount is preferably 1.0 g / m ２More preferably, 2.0 g / m ２ More preferably, 3.0 g / m ２ More preferably, 5.0 g / m ２ The treatment time may be adjusted so that the tin deposition amount is 35.0 g / m or more. ２ More preferably, 25.0 g / m or less. ２ More preferably 20.0 g / m or less ２ Particularly preferably 15.0 g / m or less ２ In particular, the treatment time is adjusted so that the tin deposition amount is 5.0 g / m or less. ２ By applying tin plating so as to satisfy the above, it is possible to suitably control the crystal orientation index Sn(200) of the (200) plane of the tin layer 30, which is preferable because it is possible to more effectively suppress gas generation and suitably control the amount of tin that dissolves in the electrolyte.

[0074] In the surface-treated metal plate for batteries 10 according to this embodiment, if the ratio of the crystal orientation indices (MI(200) / MI(211)) of the metal substrate 20 and the crystal orientation index Sn(200) of the tin layer 30 are controlled within the above-mentioned ranges, a heat treatment (e.g., a reflow treatment) may be performed after the tin layer 30 is formed on the metal substrate 20.

[0075] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The methods for evaluating each property are as follows.

[0076] <X-ray Diffraction (XRD) Measurement (Crystal Orientation Index of Metal Substrate 20 and Tin Layer 30)> X-ray diffraction (XRD) measurement was performed on the surface-treated metal sheet for batteries 10 obtained in each example and comparative example to confirm the crystal orientation index of the metal substrate 20 and the tin layer 30. A Rigaku SmartLab was used as the X-ray diffraction measurement device, and the obtained surface-treated metal sheet for batteries 10 was cut into 30 mm x 30 mm samples to serve as measurement samples. The specific measurement conditions for the X-ray diffraction (XRD) measurement were as follows: (Apparatus configuration) X-ray source: CuKα Goniometer radius: 300 mm Optical system: focusing method (incident side slit system) Soller slit: 5° Longitudinal limiting slit: 5 mm Divergence slit: 1 / 2° (receiving side slit system) Scattering slit: 1 / 2° Soller slit: 5° Receiving slit: 0.3 mm Monochromatization method: counter monochromator method Detector: scintillation counter (Measurement parameters) Tube voltage-tube current: 45 kV 200 mA Scanning axis: 2θ / θ Scanning mode: continuous Measurement range: 2θ 30 to 90° Scanning speed: 10° / min Step: 0.05°

[0077] The obtained peak intensity values ​​were subjected to background subtraction using PDXL, an integrated powder X-ray analysis software manufactured by Rigaku Corporation, and data analysis was carried out.

[0078] For the surface-treated metal plate 10 for batteries obtained in each example and comparative example, the diffraction intensity of each iron crystal plane on the surface of the metal substrate 20 was measured using the X-ray diffraction (XRD) measurement method described above. Then, using the obtained diffraction intensity of iron and the diffraction intensity of the standard iron powder, the crystal orientation indices of the (200) and (211) planes on the surface of the metal substrate 20 were determined, and the ratio of the crystalline orientation indices (MI(200) / MI(211)) was calculated. Note that the diffraction angles of each iron crystal plane and the diffraction angles of each crystal plane of the standard iron powder were those described in Diffraction ICDD PDF-2 2014 database 03-065-4899.

[0079] For the surface-treated metal sheets for batteries 10 obtained in each example and comparative example, the diffraction intensity of each crystal plane of tin on the surface of the tin layer 30 was measured by the X-ray diffraction (XRD) measurement method described above, and then the obtained diffraction intensity of tin and the diffraction intensity of standard tin powder were used to determine the crystal orientation index of the (200) plane on the surface of the tin layer 30. Note that the diffraction angles of each crystal plane of tin and the diffraction angles of each crystal plane of the standard tin powder were those described in 00-004-0673 of the Diffraction ICDD PDF-2 2014 database.

[0080] <Measurement of thickness of metal substrate 20> The surface-treated metal sheet for batteries 10 obtained in each example and comparative example was cut, and the cross section was polished. Then, the thickness of the metal substrate 20 was determined from an image obtained using a scanning electron microscope (manufactured by JEOL Ltd., model: JSM-IT500).

[0081] <Measurement of tin deposition amount of tin layer 30 and calculation of thickness> The tin deposition amount of the surface-treated metal sheet for batteries 10 obtained in each example and comparative example was quantified by a calibration curve method using X-ray fluorescence (XRF) measurement. The X-ray fluorescence device used was a ZSX Primus IV manufactured by Rigaku Corporation. In the X-ray fluorescence measurement, it was confirmed that the metal elements contained in the tin layer 30 of the surface-treated metal sheet for batteries 10 could be quantified by the calibration curve method. The thickness of the tin layer 30 was calculated by multiplying the tin deposition amount determined by the above method by the density of tin (g / cm ３ ) and converted into thickness (dividing the amount of tin deposited by the density).

[0082] <Evaluation of Gas Generation Inhibition by Corrosion Current Density Measurement> The gas generation inhibition effect of the surface-treated metal sheets 10 for batteries obtained in each Example and Comparative Example was evaluated by measuring the corrosion current density when immersed in an alkaline solution. Specifically, as a test simulating a local cell with deposited zinc, a zinc plate was used as the counter electrode, and the obtained surface-treated metal sheets 10 for batteries were immersed in an alkaline solution and the corrosion current density was measured using an electrochemical measurement system, thereby evaluating the gas generation inhibition. It can be determined that the smaller the corrosion current density 30 seconds after immersion in the alkaline solution, the higher the gas generation inhibition effect. The gas generation inhibition effect was evaluated as follows according to the corrosion current density value. A+: Corrosion current density 200 μA / cm２ A: Corrosion current density 200 μA / cm ２ Super, 300μA / cm ２ B: Corrosion current density 300 μA / cm ２ Super, 600μA / cm ２ C: Corrosion current density 600 μA / cm ２ Super

[0083] The corrosion current density measurement was carried out under the following conditions, and the corrosion current density (unit: μA / cm) generated between the test electrode and the counter electrode in a 30 wt % potassium hydroxide solution was measured. ２ ) was measured. Measuring device: HZ7000 manufactured by Hokuto Denko Corporation Test electrode: zinc plate (evaluation area 20 x 20 mm, thickness 0.5 mm) Counter electrode: measurement sample (measurement diameter φ6 mm) Measurement method: no-resistance ammeter

[0084] <Evaluation of Defects in Tin Layer 30 by Salt Spray Test (SST)> Test pieces measuring 60 mm wide x 130 mm long were prepared for the surface-treated metal sheets for batteries 10 obtained in each Example and Comparative Example. Next, a salt spray test (SST) was performed in accordance with JIS Z 2371, and defects in the tin layer 30 were evaluated by visually observing the state of rust on the surface in the center (30 mm x 30 mm) of the surface-treated metal sheets for batteries 10. The neutral salt spray test was performed under the following conditions: Spray chamber temperature: 35°C ± 2°C Salt concentration: 50 g / L ± 5 g / L Test time: 24 hours

[0085] The smaller the maximum diameter of the rust (in the width direction of the test piece) and the fewer the number of rust particles, the fewer defects in the tin layer 30 where the amount of tin adhesion is locally low, and the more excellent the durability of the surface-treated metal sheet for batteries 10. The durability of the surface-treated metal sheet for batteries 10 was evaluated as follows: A: The maximum diameter of the rust particles is 2 mm or less, and the number of rust particles is 10 or less; B: The maximum diameter of the rust particles is 2 mm or less, and the number of rust particles is more than 10 but not more than 35; C: The maximum diameter of the rust particles is more than 2 mm, or the number of rust particles is more than 35.

[0086] The reason why the durability of the surface-treated metal sheet 10 for batteries as a battery can be evaluated by a salt spray test is as follows. Because the surface-treated metal sheet 10 for batteries has a tin layer 30 formed on a metal substrate 20, even if salt water is sprayed onto the surface-treated metal sheet 10, the salt water will not come into contact with the metal substrate 20, and almost no rust should occur on the surface of the surface-treated metal sheet 10 for batteries. Visual observation of rust in a salt spray test indicates the presence of defects (poor plating) in the tin layer 30, causing the metal substrate 20 to be partially exposed to salt water. In a surface-treated metal sheet 10 for batteries having defects in the tin layer 30, repeated charging and discharging in a harsh electrolyte environment is expected to expose a portion of the metal substrate due to the defects, resulting in increased gas generation. From the above, it can be concluded that the more rust occurs in the salt spray test, the more defects there are in the tin layer 30, and the poorer the battery's durability. Conversely, the less rust occurs in the salt spray test, the fewer defects there are in the tin layer 30, and the better the battery's durability.

[0087] Example 1 First, a low-carbon aluminum-killed steel substrate was prepared having the following chemical composition: C: 0.04 wt %, Mn: 0.32 wt %, Si: 0.01 wt %, P: 0.012 wt %, S: 0.014 wt %, balance: Fe and unavoidable impurities.

[0088] Next, the prepared substrate was cold-rolled at a rolling reduction of 85% to 95%, and then heat-treated by continuous annealing under conditions of a heat treatment temperature of 700° C., a soaking time of 60 seconds, and a reducing atmosphere.

[0089] Next, re-rolling (secondary cold rolling) was performed at a rolling reduction of 40% to 50%, followed by heat treatment by continuous annealing under conditions of a heat treatment temperature of 700°C, a soaking time of 30 seconds, and a reducing atmosphere, and re-rolling (tertiary cold rolling) was performed at a rolling reduction of 60% to 70% to obtain a metal substrate 20 (thickness: 0.06 mm). The rolling conditions and heat treatment conditions are shown in Table 1.

[0090] Next, the obtained metal substrate 20 was subjected to electrolytic degreasing and pickling by immersion in sulfuric acid, and then tin plating was performed under the following conditions to form a tin layer 30 on both sides of the metal substrate 20. The tin plating conditions were as follows. The tin plating treatment time was set under conditions such that the amount of tin deposited was the amount shown in Table 2, and a surface-treated metal sheet 10 for batteries was obtained. The obtained surface-treated metal sheet 10 for batteries was then subjected to the above-mentioned measurements. The results are shown in Table 2. (Bath composition) Stannous sulfate: 80 g / L Sulfuric acid: 80 g / L Additive (product name "UTB230R", manufactured by Ishihara Chemical Co., Ltd.): 15 mL / L (Plating conditions) pH: 1.0 or less Bath temperature: 45°C Current density: 5.0 A / dm ２

[0091] Example 2-4 A surface-treated metal sheet 10 for batteries was obtained in the same manner as in Example 1, except that tin plating was performed under the conditions shown in Table 2. The above-mentioned measurements were then carried out on the obtained surface-treated metal sheet 10 for batteries. The results are shown in Table 2.

[0092] Example 5 First, an ultra-low carbon aluminum-killed steel substrate was prepared, having the following chemical composition: C: 0.002 wt %, Mn: 0.2 wt %, Si: 0.01 wt %, P: 0.012 wt %, S: 0.014 wt %, balance: Fe and unavoidable impurities.

[0093] Next, the prepared substrate was cold-rolled at a rolling reduction of 85% to 95%, followed by heat treatment by continuous annealing at a heat treatment temperature of 700°C for a soaking time of 30 seconds in a reducing atmosphere, and then re-rolled (secondary cold rolling) at a rolling reduction of 60% to 70% to obtain a metal substrate 20 (thickness: 0.06 mm). The rolling conditions and heat treatment conditions are shown in Table 1.

[0094] Next, the surface-treated metal sheet for batteries 10 was obtained in the same manner as in Example 1, except that the obtained metal substrate 20 was tin-plated under the tin plating conditions set to the values ​​shown in Table 2. Then, the obtained surface-treated metal sheet for batteries 10 was subjected to the above-mentioned measurements. The results are shown in Table 2.

[0095] Example 6 A low-carbon aluminum-killed steel substrate having the same chemical composition as in Example 1 was prepared, except that the thickness of the substrate was changed. This substrate was cold-rolled at a reduction ratio of 85% to 95%, and then heat-treated by continuous annealing at a heat treatment temperature of 700°C for a soaking time of 30 seconds in a reducing atmosphere. The substrate was then re-rolled at a reduction ratio of 70% to 80%, to obtain a metal substrate 20 (thickness: 0.04 mm). The rolling conditions and heat-treatment conditions are shown in Table 1.

[0096] Next, the obtained metal substrate 20 was subjected to electrolytic degreasing and pickling by immersion in sulfuric acid, and then tin plating was performed under the following conditions to form a tin layer 30 on both sides of the metal substrate 20. The tin plating conditions were as follows. The tin plating treatment time was set under conditions such that the amount of tin deposited was the amount shown in Table 2, thereby obtaining a surface-treated metal sheet 10 for batteries. The obtained surface-treated metal sheet 10 for batteries was then subjected to the above-mentioned measurements. The results are shown in Table 2. (Bath composition) Tin ions: 20 g / L Sulfuric acid: 45 mL / L Additive (product name "Technistan TP Additive", manufactured by Technic Japan Co., Ltd.): 25 mL / L (Plating conditions) pH: 1.0 or less Bath temperature: 45°C Current density: 1.0 A / dm ２

[0097] <Examples 7 to 11> Surface-treated metal sheets 10 for batteries were obtained in the same manner as in Example 6, except that tin plating was performed under the conditions shown in Table 2. The above-mentioned measurements were then carried out on the obtained surface-treated metal sheets 10 for batteries. The results are shown in Table 2.

[0098] Examples 12-14 A surface-treated metal sheet 10 for batteries was obtained in the same manner as in Example 5, except that the additive in the tin plating bath was changed to Technic Japan Co., Ltd., product name "Technistan TP Additive," and the tin plating conditions were changed as shown in Table 2. Then, the above-mentioned measurements were carried out on the obtained surface-treated metal sheet 10 for batteries. The results are shown in Table 2.

[0099] Example 15 A low-carbon aluminum-killed steel substrate prepared in the same manner as in Example 1 was cold-rolled at a rolling reduction of 80% to 90% to obtain a metal substrate 20 (thickness: 0.30 mm). The rolling conditions are shown in Table 1.

[0100] Next, the surface-treated metal sheet for batteries 10 was obtained in the same manner as in Example 6, except that the tin plating conditions for the obtained metal substrate 20 were changed as shown in Table 2. Then, the above-mentioned measurements were carried out on the obtained surface-treated metal sheet for batteries 10. The results are shown in Table 2.

[0101] Example 16 A surface-treated metal sheet for batteries 10 was obtained in the same manner as in Example 15, except that tin plating was performed under the conditions shown in Table 2. The above-mentioned measurements were then carried out on the obtained surface-treated metal sheet for batteries 10. The results are shown in Table 2.

[0102] Example 17 A low-carbon aluminum-killed steel substrate prepared in the same manner as in Example 1 was cold-rolled at a rolling reduction of 80% to 90%, and then heat-treated by continuous annealing under conditions of a heat treatment temperature of 800°C, a soaking time of 60 seconds, and a reducing atmosphere, to obtain a metal substrate 20 (thickness 0.35 mm). The rolling conditions and heat-treatment conditions are shown in Table 1.

[0103] Next, the surface-treated metal sheet for batteries 10 was obtained in the same manner as in Example 6, except that the tin plating conditions for the obtained metal substrate 20 were changed as shown in Table 2. Then, the above-mentioned measurements were carried out on the obtained surface-treated metal sheet for batteries 10. The results are shown in Table 2.

[0104] Example 18 A surface-treated metal sheet for batteries 10 was obtained in the same manner as in Example 17, except that tin plating was performed under the conditions shown in Table 2. The above-mentioned measurements were then carried out on the obtained surface-treated metal sheet for batteries 10. The results are shown in Table 2.

[0105] Comparative Examples 1-4 A surface-treated metal sheet for batteries 10 was obtained in the same manner as in Example 5, except that the tin plating conditions were changed as shown in Table 2. The above-described measurements were then carried out on the obtained surface-treated metal sheet for batteries 10. The results are shown in Table 2.

[0106] Comparative Examples 5 to 7 A low-carbon aluminum-killed steel substrate prepared in the same manner as in Example 1 was cold-rolled at a rolling reduction of 80% to 90%, and then heat-treated by continuous annealing under conditions of a heat treatment temperature of 700°C, a soaking time of 30 seconds, and a reducing atmosphere.

[0107] Next, re-rolling (secondary cold rolling) was performed at a rolling reduction of 40% to 50%, and then heat treatment was performed by box annealing under conditions of a heat treatment temperature of 600°C, a soaking time of 36,000 seconds, and a reducing atmosphere, to obtain a metal substrate 20 (thickness 0.11 mm). The rolling conditions and heat treatment conditions are shown in Table 1.

[0108] Next, the surface-treated metal sheet for batteries 10 was obtained in the same manner as in Comparative Example 1, except that the obtained metal substrate 20 was tin-plated under the tin plating conditions set to the values ​​shown in Table 2. Then, the obtained surface-treated metal sheet for batteries 10 was subjected to the above-mentioned measurements. The results are shown in Table 2.

[0109] Comparative Examples 8-9 A low-carbon aluminum-killed steel substrate prepared in the same manner as in Example 1 was cold-rolled at a rolling reduction of 80% to 90%, and then heat-treated by box annealing in a reducing atmosphere at a heat treatment temperature of 700°C for a soaking time of 54,000 seconds to obtain a metal substrate 20 (thickness: 0.30 mm). The rolling conditions and heat-treatment conditions are shown in Table 1.

[0110] Next, the surface-treated metal sheet for batteries 10 was obtained in the same manner as in Example 6, except that the tin plating conditions for the obtained metal substrate 20 were changed as shown in Table 2. Then, the above-mentioned measurements were carried out on the obtained surface-treated metal sheet for batteries 10. The results are shown in Table 2.

[0111] Comparative Example 10 A surface-treated metal sheet for batteries 10 was obtained and evaluated in the same manner as in Example 6, except that the tin plating conditions were changed as shown in Table 2. The results are shown in Table 2.

[0112]

[0113]

[0114] As shown in Table 1, in a surface-treated metal sheet for batteries 10 in which the ratio of the crystal orientation index MI(200) of the (200) plane to the crystal orientation index MI(211) of the (211) plane of the metal substrate 20 (MI(200) / MI(211)) is 1.1 or more and the crystal orientation index Sn(200) of the (200) plane of the tin layer 30 is 2.95 or less, the corrosion current density is reduced and gas generation can be effectively suppressed. Furthermore, the amount of rust generated after a salt spray test is small and defects in the tin layer 30 are suppressed, so the material can be determined to have excellent durability as a battery (Examples 1-18).

[0115] More specifically, in Example 1-18, the ratio of the crystal orientation indexes (MI(200) / MI(211)) of the metal substrate 20 was 1.1 or more, and the crystal orientation index Sn(200) of the tin layer 30 was 2.95 or less, so that the corrosion current density was 600 μm / cm ２ The results were as follows: It was confirmed that the gas generation suppression effect was excellent, and the amount of rust generated after the salt spray test was small, so that defects in the tin layer 30 were suppressed.

[0116] In addition, in Examples 1-11 and 13-18, the metal substrate 20 and the tin layer 30 satisfied the range of the crystal orientation index described above, and the ratio of the crystal orientation index Sn(200) of the (200) plane of the tin layer 30 to the thickness (μm) of the tin layer 30 (Sn(200) / thickness (μm) of the tin layer 30) was 6.00 or less, so that the corrosion current density was 300 μm / cm ２ Furthermore, in Examples 1-11 and 14-18, the ratio of the crystal orientation index Sn(200) of the (200) plane of the tin layer 30 to the thickness (μm) of the tin layer 30 (Sn(200) / thickness (μm) of the tin layer 30) was 3.00 or less, and therefore the corrosion current density was 200 μm / cm ２ The results were as follows, and it was confirmed that the gas generation suppression effect was significantly superior.

[0117] Furthermore, in Examples 2-11, 14, 16, and 18, the metal substrate 20 and the tin layer 30 satisfied the above-mentioned range of the crystal orientation index, and the tin coating amount in the tin layer 30 was 7.4 g / m ２As a result of the above (the thickness of the tin layer 30 is 1.0 μm or more), it was confirmed that overall defects in the tin layer 30 are more effectively suppressed, and the effect of suppressing gas generation and the durability as a battery are significantly superior.

[0118] On the other hand, in Comparative Example 1-10, either the ratio of the crystal orientation index MI(200) of the (200) plane to the crystal orientation index MI(211) of the (211) plane of the metal substrate 20 (MI(200) / MI(211)) or the crystal orientation index Sn(200) of the (200) plane of the tin layer 30 was outside the above-mentioned range, and therefore it was confirmed that the surface-treated metal plate for batteries 10 could not suppress gas generation and ensure durability as a battery at the same time.

[0119] More specifically, in Comparative Examples 1-7 and 10, in which the crystal orientation index Sn(200) of the (200) plane of the tin layer 30 was greater than 2.95, the corrosion current density was high, gas generation was significant, and the amount of rust generated was large, resulting in poor durability as a battery. Furthermore, in Comparative Examples 8-9, in which the crystal orientation index Sn(200) of the (200) plane of the tin layer 30 was 2.95 or less but the crystal orientation index ratio (MI(200) / MI(211)) of the metal substrate 20 was less than 1.1, the corrosion current density was able to be kept low, but due to the presence of defects in the tin layer 30, the amount of rust generated after the salt spray test was large, resulting in poor durability as a battery.

[0120] 10... Surface-treated metal sheet for battery 20... Metal substrate 30... Tin layer

Claims

1. A surface-treated metal sheet for batteries comprising: a metal substrate; and a tin layer provided on at least one surface of the metal substrate, wherein the ratio (MI(200) / MI(211)) of the crystal orientation index MI(200) of the (200) plane of the metal substrate to the crystal orientation index MI(211) of the (211) plane of the metal substrate is 1.1 or more; and the crystal orientation index Sn(200) of the (200) plane of the tin layer is 2.95 or less.

2. The surface-treated metal sheet for batteries according to claim 1, wherein the metal substrate is an iron-based metal substrate.

3. The surface-treated metal sheet for batteries according to claim 2, wherein the iron-based metal substrate is a steel sheet.

4. The surface-treated metal sheet for batteries according to claim 3, wherein the steel sheet is low-carbon steel or ultra-low-carbon steel.

5. The surface-treated metal sheet for batteries according to any one of claims 1 to 4, wherein the thickness of the metal substrate is 0.01 mm to 1.2 mm.

6. The tin coating amount in the tin layer is 1.0 g / m ２ Above, 35.0g / m ２ The surface-treated metal sheet for batteries according to any one of claims 1 to 5, wherein:

7. The surface-treated metal sheet for batteries according to any one of claims 1 to 6, wherein the thickness of the tin layer is 0.15 μm or more and 5.00 μm or less.

8. The surface-treated metal sheet for batteries according to any one of claims 1 to 7, wherein the ratio of the crystal orientation index Sn(200) of the (200) plane of the tin layer to the thickness (µm) of the tin layer (Sn(200) / thickness (µm) of tin layer) is 6.00 or less.

9. The surface-treated metal sheet for batteries according to claim 8, wherein the ratio of the crystal orientation index Sn(200) of the (200) plane of the tin layer to the thickness (μm) of the tin layer (Sn(200) / thickness (μm) of the tin layer) is 3.00 or less.

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