Ferritic stainless steel foil, electrode, and battery

Abstract

To provide ferritic stainless steel foil that offers excellent corrosion resistance.SOLUTION: The ferritic stainless steel foil disclosed in this invention comprises a foil main body made of ferritic stainless steel. The diffraction intensity I110 of the {110} plane, the diffraction intensity I200 of a {200} plane, and the diffraction intensity I211 of the {211} plane obtained by focusing X-ray diffraction measurement on the foil body satisfy formula (1). I110 / (I110+I200+I211)≤0.16 (1)SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a ferritic stainless steel foil, an electrode using the ferritic stainless steel foil as a current collector, and a battery using the electrode, and more specifically to a ferritic stainless steel foil used as a current collector for a secondary battery. [Background technology]

[0002] Batteries such as primary batteries and secondary batteries have been used as power sources for various electronic devices. In recent years, secondary batteries, typified by lithium-ion batteries, have become increasingly popular due to the widespread use of small electronic devices such as home video cameras, laptops, and smartphones.

[0003] A secondary battery includes electrodes having a positive electrode and a negative electrode, and an electrolyte. Both the positive electrode and the negative electrode have an electrode mixture layer formed on a current collector. The electrode mixture layer is a layer containing an active material. The current collector has the function of supplying current to the active material and the function of serving as a substrate for supporting the electrode mixture layer.

[0004] Traditionally, electrolyte solutions have been used as electrolytes in secondary batteries. However, because electrolyte solutions contain flammable organic solvents, the temperature range in which they can be used is narrow. For this reason, in recent years, development of all-solid-state batteries that use solid electrolytes instead of electrolyte solutions has been progressing. Because all-solid-state batteries do not contain organic solvents, stable battery performance can be achieved over a wide temperature range. Among the solid electrolytes used in all-solid-state batteries, sulfide-based solid electrolytes, including LPS (Lithium Phosphorus Sulfide), have particularly high ionic conductivity. Therefore, the use of sulfide-based solid electrolytes can achieve high output in all-solid-state batteries.

[0005] On the other hand, when a sulfide-based solid electrolyte is used, the current collector may be corroded by sulfides. Corrosion of the current collector results in a decrease in battery performance. In other words, the current collector must have high corrosion resistance. For this reason, the use of highly corrosion-resistant stainless steel as the current collector material is being considered. Among stainless steels, ferritic stainless steel in particular has lower electrical resistance and higher conductivity than austenitic stainless steel. For this reason, ferritic stainless steel is suitable as a current collector material.

[0006] However, even when ferritic stainless steel is used as a current collector, corrosion reactions due to sulfide-based solid electrolytes still occur in all-solid-state batteries, so there is a need for technology to further improve the corrosion resistance of ferritic stainless steel.

[0007] A technology for improving the corrosion resistance of ferritic stainless steel for current collector applications is proposed in International Publication No. 2021 / 006089 (Patent Document 1).

[0008] Patent Document 1 discloses a ferritic stainless steel sheet for use as a current collector in a sulfide-based solid battery, which contains 0.001 to 0.050% C, 0.01 to 2.00% Si, 0.01 to 1.00% Mn, 0.050% or less P, 0.010% or less S, 18.00 to 32.00% Cr, 0.01 to 4.00% Ni, 0.001 to 0.150% Al, and 0.050% or less N, with the balance being Fe and unavoidable impurities. Patent Document 1 also describes that this ferritic stainless steel sheet exhibits excellent sulfidation resistance when the Cr content is increased to 18.00% or more. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] International Publication No. 2021 / 006089 Summary of the Invention [Problem to be solved by the invention]

[0010] However, the corrosion resistance of ferritic stainless steel may be improved by a means different from that of the ferritic stainless steel sheet disclosed in Patent Document 1.

[0011] An object of the present disclosure is to provide a ferritic stainless steel foil that can provide excellent corrosion resistance, an electrode that uses the ferritic stainless steel foil as a current collector, and a battery that uses the electrode. [Means for solving the problem]

[0012] The ferritic stainless steel foil of the present disclosure is A foil body made of ferritic stainless steel, The diffraction intensity I of the {110} plane obtained by focusing X-ray diffraction measurement on the foil body 110 and the diffraction intensity of the {200} plane I 200 and the diffraction intensity of the {211} plane I 211 and satisfy the formula (1). I 110 / (I 110 +I 200 +I 211 )≦0.16 (1)

[0013] The electrode of the present disclosure comprises: The ferritic stainless steel foil; and an electrode mixture layer formed on the surface of the ferritic stainless steel foil.

[0014] The battery of the present disclosure comprises: The electrode; and an electrolyte. [Effects of the Invention]

[0015] The ferritic stainless steel foil of the present disclosure provides excellent corrosion resistance. The electrode of the present disclosure comprises the ferritic stainless steel foil of the present disclosure. The battery of the present disclosure comprises the electrode of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present inventors have investigated means for improving the corrosion resistance of ferritic stainless steel foil, and as a result, have made the following findings.

[0017] In Patent Document 1, the Cr content of ferritic stainless steel is increased to improve its corrosion resistance. Thus, the inclusion of alloying elements that improve corrosion resistance is effective for improving the corrosion resistance of ferritic stainless steel foil. However, increasing the content of alloying elements can reduce the workability of the ferritic stainless steel foil and increase manufacturing costs. Therefore, the present inventors focused on the crystal orientation of the foil body rather than the chemical composition of the foil body in a ferritic stainless steel foil having a foil body made of ferritic stainless steel.

[0018] In the body-centered cubic lattice of the ferritic stainless steel foil, the {110} plane is the lattice plane with the most densely packed atoms (close-packed atomic plane). Close-packed atomic planes such as the {110} plane serve as slip planes for dislocations.

[0019] In the manufacturing process of ferritic stainless steel foil and in the manufacturing process of batteries using ferritic stainless steel foil as a current collector, processing involving deformation of the foil itself is carried out. During such processing, fine cracks may occur in the foil itself due to cleavage fracture. The occurrence of cracks during processing is more likely when the {110} plane, which is both the close-packed atomic plane and the slip plane, is oriented parallel or perpendicular to the depth direction of the foil itself (the normal direction to the surface of the foil itself). Furthermore, corrosion of ferritic stainless steel foil preferentially progresses along these fine cracks. In other words, the more the {110} plane is oriented parallel or perpendicular to the depth direction, the more likely fine cracks will occur during processing, which accelerates the progression of corrosion of the ferritic stainless steel foil.

[0020] The crystal orientation of the foil body can be evaluated by focusing X-ray diffraction measurement. The three major lattice planes detected by focusing X-ray diffraction measurement of the foil body are the {110}, {200}, and {211} planes. The lower the ratio of the diffraction intensity of the {110} plane to the sum of the diffraction intensities of the three lattice planes, the lower the orientation of the {110} plane in the depth direction. This can suppress the generation of microcracks in the foil body during processing. Therefore, the progression of corrosion in the ferritic stainless steel foil is suppressed. As a result, the corrosion resistance of the ferritic stainless steel foil can be improved.

[0021] Based on the above findings, the inventors have investigated the relationship between the diffraction intensity of each lattice plane in the foil body, obtained by focusing X-ray diffraction measurement, and corrosion resistance. As a result, the diffraction intensity I of the {110} plane, obtained by focusing X-ray diffraction measurement of the foil body, 110 and the diffraction intensity of the {200} plane I 200 and the diffraction intensity of the {211} plane I 211 However, the present inventors have found that if formula (1) is satisfied, excellent corrosion resistance can be obtained in the ferritic stainless steel foil. I 110 / (I 110 +I 200 +I 211 )≦0.16 (1)

[0022] The ferritic stainless steel foil of this embodiment, the electrode of this embodiment, and the battery of this embodiment have been completed based on the above technical concept, and have the following configurations.

[0023] The ferritic stainless steel foil of the first configuration is A foil body made of ferritic stainless steel, The diffraction intensity I of the {110} plane obtained by focusing X-ray diffraction measurement on the foil body 110 and the diffraction intensity of the {200} plane I 200 and the diffraction intensity of the {211} plane I 211 and satisfy the formula (1). I 110 / (I 110 +I200 +I 211 )≦0.16 (1)

[0024] The ferritic stainless steel foil of the second configuration is A ferritic stainless steel foil of a first configuration, further comprising: I defined by formula (2) in the region from a depth of 0.38 μm to a depth of 2.82 μm starting from the surface of the foil body R The maximum value of I MAX is 15.0 or greater. I R =II 110 / II 211 (2) Here, II in formula (2) 110 is substituted with the integrated intensity of the {110} plane obtained by grazing incidence X-ray diffraction, and II 211 is substituted with the integrated intensity of the {211} plane obtained by grazing incidence X-ray diffraction.

[0025] The ferritic stainless steel foil of the third configuration is A ferritic stainless steel foil having a first or second configuration, The chemical composition of the foil body is, in mass%, C: 0.001 to 0.030%, Si: 0.01 to 1.00%, Mn: 0.01 to 1.00%, P: 0.050% or less, S: 0.030% or less, Ni: 0.01 to 0.50% Cr: 12.00~20.00%, Mo: 0.01 to 2.50% N: 0~0.100%, Ti: 0 to 0.80% Nb: 0 to 0.80%, and Zr: 0 to 0.80%; The balance is Fe and impurities.

[0026] The electrodes of the first configuration are: A ferritic stainless steel foil having any one of the first to third configurations; and an electrode mixture layer formed on the surface of the ferritic stainless steel foil.

[0027] The battery of the first configuration comprises: a first configuration of electrodes; and an electrolyte.

[0028] The battery in the second configuration is 1. A battery of a first configuration, comprising: The electrolyte is a sulfide-based solid electrolyte.

[0029] The ferritic stainless steel foil of this embodiment, the electrode of this embodiment, and the battery of this embodiment will be described in detail below. Note that "%" for elements means mass % unless otherwise specified.

[0030] [Composition of ferritic stainless steel foil] The ferritic stainless steel foil of this embodiment has a foil body made of ferritic stainless steel. That is, the ferritic stainless steel foil of this embodiment may be composed only of a foil body made of ferritic stainless steel. Here, ferritic stainless steel means a steel with a Cr content of 10.5% or more and a microstructure mainly composed of ferrite.

[0031] [Regarding formula (1)] In the ferritic stainless steel foil of this embodiment, the diffraction intensity I of the {110} plane obtained by focusing X-ray diffraction measurement of the foil body is 110 and the diffraction intensity of the {200} plane I 200 and the diffraction intensity of the {211} plane I 211 and satisfy the formula (1). I 110 / (I 110 +I 200 +I 211 )≦0.16 (1)

[0032] Define F1 as follows: F1=I110 / (I 110 +I 200 +I 211 ) F1 is an index of the orientation of the {110} plane in the depth direction. If F1 is 0.16 or less, the proportion of {110} planes oriented parallel or perpendicular to the depth direction within the foil body is sufficiently low. In this case, the occurrence of fine cracks in the foil body during processing can be sufficiently suppressed. As a result, the ferritic stainless steel foil exhibits excellent corrosion resistance.

[0033] The lower limit of F1 is not particularly limited. In consideration of normal industrial production, the lower limit of F1 is, for example, 0, and more preferably 0.01. The upper limit of F1 is preferably 0.14, and more preferably 0.12.

[0034] [Method for measuring the diffraction intensity of each lattice plane] Diffraction intensity of {110} plane I 110 , {200} plane diffraction intensity I 200 , and the diffraction intensity of the {211} plane I 211 is calculated in the following way:

[0035] A test piece is taken from the surface of the ferritic stainless steel foil body as the observation surface. The size of the test piece is not particularly limited, but it is preferable that it be larger than the X-ray irradiation area. The location from which the test piece is taken is also not particularly limited, but for example, the center of the foil body width. Focused X-ray diffraction measurement is performed on the observation surface of the test piece using an X-ray diffractometer to obtain a diffraction profile. The incident direction of the X-rays is parallel to a plane containing the rolling direction and a direction perpendicular to the surface of the foil body. For example, an ULTIMA-III (trade name) manufactured by Rigaku Corporation can be used for the measurement. The X-ray diffractometer uses a CuKα source for the measurement. The X-ray diffraction measurement is performed with an acceleration voltage of 40 kV, an acceleration current of 40 mA, a divergence slit of 1 / 2°, a scan speed of 0.2° / min, and a sampling width of 0.02°. A monochromator is placed in front of the detector. Peaks of the {110}, {200}, and {211} planes are identified from the obtained diffraction profile. From the peaks of each identified lattice plane, the diffraction intensity of the {110} plane I110 , {200} plane diffraction intensity I 200 , and the diffraction intensity of the {211} plane I 211 Ask for.

[0036] Obtained I 110 , I 200 , and I 211 F1 is calculated based on the above. Note that F1 is a value rounded off to two decimal places.

[0037] [I R The maximum value of I MAX About Preferably, in the ferritic stainless steel foil of this embodiment, the I defined by formula (2) in the region from a depth of 0.38 μm to a depth of 2.82 μm starting from the surface of the foil body is R The maximum value of I MAX is 15.0 or greater. I R =II 110 / II 211 (2) Here, II in formula (2) 110 is substituted with the integrated intensity of the {110} plane obtained by grazing incidence X-ray diffraction, and II 211 is substituted with the integrated intensity of the {211} plane obtained by grazing incidence X-ray diffraction.

[0038] In the above-mentioned F1, the focus was on the {110} crystal orientation throughout the entire foil body. The inventors further investigated ways to further improve the corrosion resistance of ferritic stainless steel foil, focusing on the {110} crystal orientation in the foil body, particularly in the surface layer. Here, the surface layer is defined as the region from the surface of the foil body to a depth of 2.82 μm.

[0039] Corrosion of ferritic stainless steel foil progresses from the surface to the depth. The {110} plane, a close-packed atomic plane, has a short interatomic distance within the plane, resulting in a strong interatomic bond. Therefore, the more perpendicularly oriented the {110} plane is to the depth direction at a given depth, the slower the corrosion rate at that depth. In particular, increasing the depth orientation of the {110} plane in the surface layer of the foil can significantly suppress the progression of corrosion originating from the surface. As mentioned above, the higher the depth orientation of the {110} plane, the more likely cracks will occur during processing. However, in the surface layer, increasing the orientation of the {110} plane can actually suppress the progression of corrosion. In other words, if the {110} plane is oriented in the depth direction in the surface layer while the overall crystal orientation of the foil can be adjusted to satisfy Equation (1), the corrosion resistance of ferritic stainless steel foil can be further improved.

[0040] The crystal orientation in the surface layer of the foil body can be evaluated by grazing incidence X-ray diffraction (GIXD). Unlike focusing methods, grazing incidence X-ray diffraction can selectively measure the crystal orientation up to any depth starting from the surface. Furthermore, grazing incidence X-ray diffraction measurements of the surface layer of the foil body primarily detect peaks of the {110} and {211} planes. The greater the ratio of the integrated intensity of the {110} plane to the integrated intensity of the {211} plane at a given depth, the more the {110} planes oriented perpendicular to the depth direction are present at that depth. In other words, to further enhance the corrosion resistance of ferritic stainless steel foil, it is preferable that the ratio of the integrated intensity of the {110} plane to the integrated intensity of the {211} plane at the surface layer of the foil body is large.

[0041] where I R is an index that represents the ratio of the amount of {110} planes to the amount of {211} planes that make up the crystal orientation in the depth direction at any depth position starting from the surface of the foil body. I in the region from the depth position of 0.38 μm to the depth position of 2.82 μm starting from the surface of the foil body RThe maximum value of I MAX is the surface I R It is an index that represents the maximum value of

[0042] I in the region from the surface of the foil body to a depth of 0.38 μm to a depth of 2.82 μm R The maximum value of I MAX If the ratio of the integrated intensity of the {110} plane to the integrated intensity of the {211} plane is 15.0 or more, the ratio of the integrated intensity of the {110} plane to the integrated intensity of the {211} plane is sufficiently large in the surface layer. In this case, the orientation of the {110} plane in the depth direction is sufficiently high in the surface layer, and the progression of corrosion originating from the surface layer can be sufficiently suppressed. As a result, the ferritic stainless steel foil can achieve even better corrosion resistance.

[0043] I MAX The lower limit is more preferably 20.0, and even more preferably 30.0. I MAX There is no particular upper limit for I. Considering normal industrial production, MAX The upper limit is, for example, 120.0.

[0044] [Method for measuring the integrated intensity of each lattice plane] Integrated intensity of {110} plane II 110 , and the integrated intensity of the {211} plane II 211 is calculated in the following way:

[0045] A test piece is taken from the surface of the ferritic stainless steel foil body as the observation surface. The size of the test piece is not particularly limited. The location from which the test piece is taken is also not particularly limited, but for example, the center of the foil body width. Measurement is performed on the observation surface of the test piece using grazing incidence X-ray diffraction. Specifically, the radiation source is CoKα radiation, the tube voltage is 40 kV, and the tube current is 135 mA. The X-ray beam is collimated using a mirror. For example, a SmartLab manufactured by Rigaku Corporation can be used for the measurement. A 5.0° Soller slit is installed on the incident side, a 5.0° Soller slit is installed on the receiving side, a parallel slit analyzer (PSA) is installed at 0.5°, receiving slit 1 (RS1) is 1.0 mm, and receiving slit 2 (RS2) is open. The incident direction of the X-rays is parallel to a plane containing the rolling direction and the direction perpendicular to the surface of the foil body.

[0046] The measurement depth from the observation surface at each incidence angle in the grazing incidence X-ray diffraction method can be calculated from the X-ray penetration depth t that satisfies μt = 1, where μ is the linear absorption coefficient. To calculate the linear absorption coefficient μ, the mass absorption coefficient of 19.11Cr-1.77Mo-78.38Fe (mass%), which corresponds to SUS444, is used, and the density is 7.75g / cm. 3 Based on this conversion method, when the incident angle is 2.0° to 15.0°, the measurement depth corresponds to a depth of 0.38 μm to a depth of 2.82 μm. Therefore, measurements are performed under nine conditions, with incident angles of 2.0°, 3.0°, 4.0°, 5.0°, 6.0°, 8.0°, 10.0°, 12.0°, and 15.0°. From the diffraction profiles obtained under each condition, the peaks of the {110} plane and the {211} plane are identified. From the peaks of each lattice plane, the integrated intensity II of the {110} plane is calculated. 110 and {211} plane integrated intensity II 211 Calculate.

[0047] Obtained II 110 and II 211 Based on equation (2), I R Calculate I R is the value obtained by rounding off the second decimal place to the first decimal place. I obtained under nine conditions corresponding to measurement depths of 0.38 to 2.82 μmR The maximum value of I MAX Let's say.

[0048] [Chemical composition] In the ferritic stainless steel foil of this embodiment, the chemical composition of the foil body may be that of a known ferritic stainless steel.

[0049] The chemical composition of the foil body of the ferritic stainless steel foil of this embodiment may satisfy, for example, any one selected from the group consisting of SUS405, SUS410L, SUS429, SUS430, SUS430LX, SUS430J1L, SUS434, SUS436L, SUS436J1L, SUS443J1, SUS444, SUS445J1, SUS445J2, SUS447J1, and SUSXM27 as specified in JIS G 4305 (2015).

[0050] The chemical composition of the foil body of the ferritic stainless steel foil of this embodiment may further satisfy, for example, any one selected from the group consisting of 403, 405, 409L, 410, 410L, 410S, 415, 420J1, 420J2, 420, 429, 429J1, 430, 430J1L, 430LX, 430Ti, 434, 436, 436J1L, 439, 441, 444, 445, 445J1, 445J2, 446, 447, and 448 as specified in ASTM A 240 (2006).

[0051] The chemical composition of the foil body of the ferritic stainless steel foil of this embodiment may contain, for example, the following elements.

[0052] C: 0.001 to 0.030% Carbon (C) increases the strength of the ferritic stainless steel foil. If the C content is 0.001% or more, this effect can be sufficiently obtained. On the other hand, if the C content is 0.030% or less, the formation of a Cr-deficient layer due to the generation of Cr carbides can be suppressed, which in turn suppresses the embrittlement of the oxide film and improves the corrosion resistance of the ferritic stainless steel foil. Therefore, the preferred C content is 0.001 to 0.030%. A more preferable lower limit of the C content is 0.003%, and even more preferably 0.005%. The upper limit of the C content is more preferably 0.025%, and even more preferably 0.020%.

[0053] Si: 0.01 to 1.00% Silicon (Si) deoxidizes steel during the steelmaking process, and if the Si content is 0.01% or more, this effect can be sufficiently obtained. On the other hand, if the Si content is 1.00% or less, the workability of the ferritic stainless steel foil is improved. Therefore, the preferred Si content is 0.01 to 1.00%. The lower limit of the Si content is more preferably 0.03%, and even more preferably 0.05%. The upper limit of the Si content is more preferably 0.90%, and even more preferably 0.80%.

[0054] Mn: 0.01 to 1.00% Manganese (Mn) increases the strength of the ferritic stainless steel foil, and if the Mn content is 0.01% or more, this effect can be sufficiently obtained. On the other hand, if the Mn content is 1.00% or less, the corrosion resistance of the ferritic stainless steel foil is improved. Therefore, the preferred Mn content is 0.01 to 1.00%. A more preferable lower limit of the Mn content is 0.03%, and even more preferably 0.05%. A more preferable upper limit of the Mn content is 0.90%, and even more preferably 0.80%.

[0055] P:0.050% or less Phosphorus (P) is an impurity. If the P content is 0.050% or less, the workability and corrosion resistance of the ferritic stainless steel foil are improved. Therefore, the preferred P content is 0.050% or less. The lower the P content, the better. However, excessively reducing the P content increases the production cost. Therefore, in consideration of normal industrial production, the lower limit of the P content is preferably more than 0%, more preferably 0.001%, and even more preferably 0.010%. A more preferable upper limit of the P content is 0.045%, and even more preferably 0.040%.

[0056] S: 0.030% or less Sulfur (S) is an impurity. If the S content is 0.030% or less, the workability and corrosion resistance of the ferritic stainless steel foil are improved. Therefore, the preferred S content is 0.030% or less. The S content is preferably as low as possible. However, excessively reducing the S content increases the production cost. Therefore, in consideration of normal industrial production, the lower limit of the S content is preferably more than 0%, more preferably 0.001%, and even more preferably 0.010%. The upper limit of the S content is more preferably 0.025%, and even more preferably 0.020%.

[0057] Ni: 0.01 to 0.50% Nickel (Ni) improves the corrosion resistance of the ferritic stainless steel foil, and if the Ni content is 0.01% or more, this effect can be sufficiently obtained. On the other hand, if the Ni content is 0.50% or less, the workability of the ferritic stainless steel foil is improved. Therefore, the Ni content is preferably 0.01 to 0.50%. A more preferable lower limit of the Ni content is 0.03%, and even more preferably 0.05%. A more preferable upper limit of the Ni content is 0.40%, and even more preferably 0.30%.

[0058] Cr: 12.00~20.00% Chromium (Cr) forms an oxide film and improves the corrosion resistance of the ferritic stainless steel foil. If the Cr content is 12.00% or more, this effect can be sufficiently obtained. On the other hand, if the Cr content is 20.00% or less, the workability of the ferritic stainless steel foil is improved. Therefore, the preferred Cr content is 12.00 to 20.00%. The lower limit of the Cr content is more preferably 12.50%, and even more preferably 13.00%. The upper limit of the Cr content is more preferably 19.00%, and even more preferably 18.00%.

[0059] Mo: 0.01 to 2.50% Molybdenum (Mo) enhances the strength and corrosion resistance of ferritic stainless steel foil, and if the Mo content is 0.01% or more, these effects can be sufficiently obtained. On the other hand, if the Mo content is 2.50% or less, the workability of the ferritic stainless steel foil is improved. Therefore, the preferred Mo content is 0.01 to 2.50%. A more preferable lower limit of the Mo content is 0.03%, and even more preferably 0.05%. A more preferable upper limit of the Mo content is 2.40%, and even more preferably 2.30%.

[0060] N: 0 to 0.100% Nitrogen (N) may not be contained. On the other hand, if the N content is 0.100% or less, the strength of the ferritic stainless steel foil increases. Therefore, the preferred N content is 0 to 0.100%. A more preferable lower limit of the N content is more than 0%, even more preferably 0.001%, and even more preferably 0.003%. The upper limit of the N content is more preferably 0.090%, and even more preferably 0.080%.

[0061] Ti: 0 to 0.80% Titanium (Ti) may not be contained. On the other hand, if the Ti content is 0.80% or less, it fixes C and suppresses the formation of Cr carbides, thereby suppressing the formation of a Cr-depleted layer. As a result, embrittlement of the oxide film is suppressed, and the corrosion resistance of the ferritic stainless steel foil is improved. Therefore, the preferred Ti content is 0 to 0.80%. A more preferable lower limit of the Ti content is more than 0%, even more preferably 0.01%, and even more preferably 0.03%. A more preferable upper limit of the Ti content is 0.70%, and even more preferably 0.60%.

[0062] Nb: 0 to 0.80% Niobium (Nb) may not be contained. On the other hand, if the Nb content is 0.80% or less, the corrosion resistance of the ferritic stainless steel foil is improved. Therefore, the Nb content is preferably 0 to 0.80%. A more preferable lower limit of the Nb content is more than 0%, even more preferably 0.01%, and even more preferably 0.03%. The upper limit of the Nb content is more preferably 0.70%, and even more preferably 0.60%.

[0063] Zr: 0 to 0.80% Zirconium (Zr) may not be contained. On the other hand, if the Zr content is 0.80% or less, the corrosion resistance of the ferritic stainless steel foil is improved. Therefore, the preferred Zr content is 0 to 0.80%. A more preferable lower limit of the Zr content is more than 0%, even more preferably 0.01%, and even more preferably 0.03%. A more preferable upper limit of the Zr content is 0.70%, and even more preferably 0.60%.

[0064] The balance of the preferred chemical composition of the foil body of the ferritic stainless steel foil of this embodiment consists of Fe and impurities. Here, the impurities in the chemical composition refer to substances that are mixed in from raw materials or the manufacturing environment during industrial production of the ferritic stainless steel foil, and are acceptable within a range that does not adversely affect the ferritic stainless steel foil of this embodiment.

[0065] Plate Thickness The thickness of the foil body of the ferritic stainless steel foil of this embodiment is not particularly limited, and is, for example, 6 to 20 μm.

[0066] [Uses of the ferritic stainless steel foil of this embodiment] The ferritic stainless steel foil of this embodiment has excellent corrosion resistance. Therefore, it is suitable for use as a current collector in an all-solid-state battery using a highly corrosive sulfide-based solid electrolyte. The ferritic stainless steel foil of this embodiment can also be used for applications other than as a current collector in a secondary battery.

[0067] [Method for producing ferritic stainless steel foil according to the present embodiment] An example of a method for producing the ferritic stainless steel foil of this embodiment will be described. The method for producing the ferritic stainless steel foil described below is one example for producing the ferritic stainless steel foil of this embodiment. Therefore, the ferritic stainless steel foil having the above-mentioned configuration may be produced by a production method other than the production method described below. However, the production method described below is a preferred example of a method for producing the ferritic stainless steel foil of this embodiment.

[0068] An example of a method for producing the ferritic stainless steel foil of this embodiment includes the following steps. (Process 1) Material preparation process (Process 2) Intermediate cold rolling process (Process 3) Intermediate annealing process (Process 4) Final cold rolling process Each step will be described below.

[0069] [(Process 1) Material preparation process] In the material preparation step, a ferritic stainless steel sheet having a thickness of several hundred μm to several mm is prepared as a material for producing the ferritic stainless steel foil of this embodiment. The material is, for example, a cold-rolled coil obtained by cold-rolling a hot-rolled coil. The material may be prepared by manufacturing or by purchasing from a third party. In other words, the process for preparing the material is not particularly limited.

[0070] When manufacturing a raw material, for example, it is manufactured by the following method. Molten steel having a desired chemical composition is manufactured. A slab is manufactured using the molten steel by continuous casting. The manufactured slab is hot worked and cold rolled to manufacture a steel plate having a thickness of several hundred μm to several mm. Through the above steps, the raw material for the ferritic stainless steel foil of this embodiment is prepared.

[0071] [(Process 2) Intermediate cold rolling process] In the intermediate cold rolling process, cold rolling is performed on the prepared material to produce an intermediate steel plate having a thickness of several tens of μm to several hundreds of μm. In the intermediate cold rolling process, cold rolling may be performed using a continuous rolling mill equipped with a plurality of rolling stands arranged in a row, or may be performed using a reversing rolling mill. There is no particular limitation on the cumulative reduction ratio in the intermediate cold rolling process.

[0072] The intermediate cold rolling step satisfies the following conditions. As will be described later, the intermediate cold rolling step and the intermediate annealing step may be alternately repeated multiple times. In this case, it is sufficient that the following conditions are satisfied in the final intermediate cold rolling step. (Condition 1) Maximum reduction rate in one pass R1 MAX is 10.0% or more. Condition 1 will be explained below.

[0073] [Maximum reduction rate in one pass R1 MAX About Here, "pass" means the operation of the material passing through one rolling stand once. In the intermediate cold rolling process, cold rolling consisting of multiple passes is carried out. "The maximum reduction ratio R1 in one pass MAX " means the reduction rate in the pass with the largest reduction rate in the intermediate cold rolling process. Maximum reduction rate in one pass R1 MAX The larger the reduction ratio R1 in one pass, the larger the strain that can be accumulated inside the intermediate steel sheet after the intermediate cold rolling process. Here, the greater the amount of strain accumulated in the intermediate steel sheet after the intermediate cold rolling process, the more recrystallization is promoted in the subsequent intermediate annealing process. In addition, the more recrystallization is promoted, the lower the orientation of the {110} plane in the depth direction. MAX If the annealing temperature is 10.0% or more, a sufficient amount of strain is introduced into the intermediate steel sheet. In this case, provided that the intermediate annealing process satisfies Condition 2 described below, the orientation of the {110} plane is also sufficiently reduced inside the intermediate steel sheet. As a result, F1 in the manufactured ferritic stainless steel foil satisfies Formula (1). Maximum reduction rate in one pass R1 MAX There is no particular upper limit to the maximum rolling reduction R1 in one pass, considering normal industrial production. MAX The upper limit is, for example, 40.0%.

[0074] [(Process 3) Intermediate annealing process] In the intermediate annealing step, bright annealing is performed on the intermediate steel sheet after the intermediate cold rolling step. Bright annealing is an annealing treatment performed in an extremely low oxygen atmosphere. The surface of the intermediate steel sheet that has been subjected to bright annealing is hardly oxidized, and the surface gloss can be maintained. The extremely low oxygen atmosphere in bright annealing is preferably a mixed gas atmosphere of H2 gas and N2 gas. The N2 fraction in the atmospheric gas is, for example, 35 to 65% by volume.

[0075] In the bright annealing performed in the intermediate annealing process, the intermediate steel sheet is passed through a heat treatment furnace in an extremely low-oxygen atmosphere at a predetermined speed. The heat treatment furnace is divided into a heating chamber, an annealing chamber, and a rapid cooling chamber in the order in which the intermediate steel sheet passes through. In the heating chamber, the intermediate steel sheet is heated and maintained at a predetermined temperature. Here, the temperature in the heating chamber is the heating temperature T (°C), and the time it takes for the intermediate steel sheet to pass through the heating chamber is the holding time t (seconds). In the annealing chamber, the intermediate steel sheet is cooled from the heating temperature T (°C) to 400°C at a predetermined cooling rate. In the rapid cooling chamber, the intermediate steel sheet cooled to 400°C is rapidly cooled to room temperature. The rapid cooling method is not particularly limited, but may be air cooling, for example.

[0076] The intermediate cold rolling step and the intermediate annealing step may be alternately repeated multiple times. For example, when the intermediate cold rolling step and the intermediate annealing step are alternately repeated twice, a first intermediate cold rolling step and a first intermediate annealing step are performed, followed by a second intermediate cold rolling step and a second intermediate annealing step.

[0077] The intermediate annealing step satisfies the following conditions: When the intermediate annealing step is performed multiple times, it is sufficient that the following conditions are satisfied in the intermediate annealing step that is performed last. (Condition 2) The heat treatment parameter FA defined by the formula (A) is 2133 or more. FA = (T-780) × (log 10 t+30) (A) Here, the heating temperature T (°C) is substituted for T in the formula (A), and the holding time t (seconds) is substituted for t.

[0078] In the intermediate annealing step, it is preferable that the following condition be further satisfied: When the intermediate annealing step is performed a plurality of times, it is only necessary that the following condition be satisfied in the intermediate annealing step that is performed last. (Preferable condition 1) The heat treatment parameter FA defined by the formula (A) is 8418 or less. Condition 2 and preferred condition 1 will be explained below.

[0079] [About the heat treatment parameter FA] In the intermediate annealing step, the higher the heating temperature T or the longer the holding time t, the more recrystallization is promoted, and the lower the orientation of the {110} plane in the depth direction. If FA is 2133 or more, the orientation of the {110} plane in the foil body in the depth direction can be sufficiently reduced. In this case, assuming that the intermediate cold rolling step satisfies condition 1, F1 in the manufactured ferritic stainless steel foil satisfies formula (1). Therefore, FA is set to 2133 or more.

[0080] On the other hand, if the FA is 8418 or less, excessive deterioration of the {110} plane orientation in the surface layer of the foil body can be suppressed. In this case, on the premise that the final cold rolling process satisfies the preferred condition 2 described later, the I in the manufactured ferritic stainless steel foil can be MAX Therefore, it is preferable that FA is 8418 or less.

[0081] [(Process 4) Final cold rolling process] In the final cold rolling step, the intermediate steel sheet after the intermediate annealing step is cold rolled again to obtain a ferritic stainless steel foil having a foil body of a predetermined thickness. A well-known cold rolling mill may be used in the final cold rolling step. For example, cold rolling may be performed using a continuous rolling mill equipped with multiple rolling stands arranged in a row, or cold rolling may be performed using a reverse rolling mill. The cumulative reduction ratio in the final cold rolling step is not particularly limited.

[0082] The final cold rolling process satisfies the following conditions: (Preferred condition 2) Maximum reduction rate in one pass R2 MAX is less than 26%. Condition 2 will be explained below.

[0083] [Maximum reduction rate in one pass R2 MAX About In the final cold rolling process, cold rolling consisting of multiple passes is carried out. The maximum reduction rate in one pass is R2 MAX" refers to the reduction rate in the pass with the largest reduction rate in the final cold rolling process. If there is even one pass with an excessively large reduction rate, intense processing heat will occur. As a result, the temperature will rise excessively in the surface layer of the intermediate steel plate, and the orientation of the {110} plane in the depth direction will decrease. The maximum reduction rate in one pass, R2 MAX When the rolling reduction is 26% or less, it means that there are no passes with rolling reductions exceeding 26%. In this case, the heat generated by processing in the surface layer is sufficiently suppressed, and excessive deterioration of the orientation of the {110} plane in the depth direction is also suppressed. As a result, assuming that the intermediate annealing process satisfies the preferred condition 1, the I MAX is 15.0 or more. Therefore, the maximum rolling reduction in one pass R2 MAX is preferably 26% or less. Maximum reduction rate in one pass R2 MAX There is no particular lower limit to the rolling reduction rate R2 in one pass, considering normal industrial production. MAX The lower limit is, for example, 5%.

[0084] The ferritic stainless steel foil of this embodiment is manufactured by the above-described manufacturing method.

[0085] [electrode] The electrode of this embodiment comprises the ferritic stainless steel foil of this embodiment and an electrode mixture layer formed on the surface of the ferritic stainless steel foil. That is, in the electrode of this embodiment, the ferritic stainless steel foil of this embodiment is used as a current collector. The electrode of this embodiment may be a positive electrode or a negative electrode. That is, the configuration of the electrode of this embodiment is not particularly limited as long as it comprises the ferritic stainless steel foil of this embodiment and an electrode mixture layer.

[0086] [Electrode mixture layer] In the electrode of this embodiment, the electrode mixture layer is not particularly limited as long as it has a known configuration. The electrode mixture layer contains an active material. The electrode mixture layer may contain materials other than the active material. The electrode mixture layer may contain, for example, a binder and a conductive additive. Furthermore, the electrode mixture layer used in an all-solid-state battery may contain, for example, a solid electrolyte.

[0087] [Active material] In the electrode of this embodiment, the active material contained in the electrode mixture layer is not particularly limited, and well-known active materials can be used. When the electrode is a positive electrode, the positive electrode active material may be, for example, LiCoO2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 The negative electrode active material may be, for example, a carbon-based material such as graphite, an alloy material such as CuSn alloy and NiTiSi alloy, a Si-based material such as Si and SiO, or Li4Ti5O 12 It may also be an oxide-based material represented by the following.

[0088] [binder] In the electrode of this embodiment, the binder contained in the electrode mixture layer is not particularly limited, and well-known binders can be used. The binder may be, for example, a rubbery polymer such as styrene-butadiene rubber or isoprene rubber, a synthetic resin such as polyethylene, polyimide, polyacrylic acid, or polyamide, a styrene-butadiene-styrene block copolymer or its hydrogenated product, a thermoplastic elastomer such as styrene-ethylene-butadiene, styrene copolymer, styrene-isoprene, or styrene block copolymer or their hydrogenated products, a soft resinous polymer such as syndiotactic 1,2-polybutadiene, ethylene-vinyl acetate copolymer, or copolymer of ethylene with an α-olefin having 3 to 12 carbon atoms, or a fluorinated polymer such as polytetrafluoroethylene, tetrafluoroethylene-ethylene copolymer, polyvinylidene fluoride, polypentafluoropropylene, or polyhexafluoropropylene.

[0089] [Conductive additive] In the electrode of this embodiment, the conductive additive contained in the electrode mixture layer is not particularly limited, and any known conductive additive can be used. The conductive additive may be, for example, acetylene black, carbon black, or ketjen black.

[0090] [Electrode manufacturing method] The method for producing the electrode of this embodiment is not particularly limited. The electrode of this embodiment is produced by a well-known method using the ferritic stainless steel foil of this embodiment as a current collector. The method for producing the electrode of this embodiment includes, for example, an electrode slurry preparation step and an electrode mixture layer formation step.

[0091] [Electrode slurry preparation process] In the electrode slurry preparation step, a composition (electrode slurry) for forming an electrode mixture layer is prepared. The electrode slurry may be prepared according to the electrode mixture layer to be obtained. For example, the electrode slurry may be prepared by kneading an active material, a binder, and a solvent. For example, the electrode slurry may be prepared by further kneading an active material, a conductive additive, a binder, and a solvent. Furthermore, when preparing an electrode slurry to be used in an all-solid-state battery, the electrode slurry may be prepared by kneading an active material, a solvent, a solid electrolyte, and a binder. The kneading method is adjusted appropriately depending on the active material, the conductive additive, the binder, the solid electrolyte, and the solvent. In other words, the electrode slurry preparation step may be performed by a known method.

[0092] [Electrode mixture layer formation process] In the electrode mixture layer forming step, an electrode mixture layer is formed on the surface of the ferritic stainless steel foil of this embodiment. Specifically, the kneaded electrode slurry is applied to the ferritic stainless steel foil of this embodiment. The application method is not particularly limited and may be a well-known method. For example, application may be performed using an applicator with a gap. Furthermore, application may be performed by spraying using a sprayer.

[0093] The electrode of this embodiment can be manufactured by the above steps.

[0094] [battery] The battery of this embodiment includes the electrode of this embodiment and an electrolyte. The battery of this embodiment may have any known configuration other than the electrode of this embodiment, and is not particularly limited. The battery of this embodiment may further include, for example, a separator. The shape of the battery of this embodiment is not particularly limited, and may be cylindrical, prismatic, coin-shaped, or sheet-shaped. Furthermore, the battery of this embodiment may be a secondary battery or a primary battery. When the battery according to this embodiment is a secondary battery, it may be, for example, a non-aqueous electrolyte secondary battery, an aqueous electrolyte secondary battery, or an all-solid-state secondary battery.

[0095] [Electrolytes] The electrolyte conducts ions between the positive electrode and the negative electrode. In the battery of this embodiment, the electrolyte is not particularly limited, and a well-known electrolyte can be used. The electrolyte may be a liquid electrolytic solution or a solid electrolyte.

[0096] The electrodes of the battery of this embodiment use the ferritic stainless steel foil of this embodiment as a current collector. Therefore, the current collector has excellent corrosion resistance. Therefore, the electrolyte of the battery of this embodiment can be a sulfide-based solid electrolyte, which is highly corrosive to the current collector. Examples of sulfide-based solid electrolytes include Li3PS4 and Li7P3S 11 It may be an LPS system represented by Li6PS5Cl x Br (1-x) (0≦x≦1) may be an argyrodite type, 10 GeP2S 12 and Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 The thiolicon represented by the following may also be used.

[0097] [Battery manufacturing method] The method for manufacturing the battery of the present embodiment is not particularly limited. For example, the battery of the present embodiment is manufactured by a well-known method by placing a laminate of the electrode of the present embodiment, an electrolyte, and a counter electrode in a battery case. [Example]

[0098] The effects of the ferritic stainless steel foil of this embodiment will be explained more specifically using examples. The conditions in the following examples are one example of conditions adopted to confirm the feasibility and effects of the ferritic stainless steel foil of this embodiment. Therefore, the ferritic stainless steel foil of this embodiment is not limited to this one example of conditions.

[0099] As a material for producing ferritic stainless steel foil, a steel plate having the chemical composition shown in Table 1 was prepared. The thickness of the steel plate was 300 μm.

[0100] [Table 1]

[0101] The material of each test number was subjected to an intermediate cold rolling process once to produce an intermediate steel plate. Specifically, the material of each test number was cold rolled using a reverse rolling mill. The maximum reduction rate R1 in one pass for each test number was MAX (%) are shown in Table 2.

[0102] [Table 2]

[0103] The intermediate steel sheets after the intermediate cold rolling process were subjected to a single intermediate annealing process. Specifically, the intermediate steel sheets of each test number were bright annealed in a mixed gas atmosphere of 35 to 65 volume percent N2 gas and the remainder H2 gas. The heating temperature T (°C), holding time t (seconds), and calculated heat treatment parameter FA for each test number are shown in Table 2.

[0104] The intermediate steel sheets after the intermediate annealing process were subjected to a final cold rolling process. In the final cold rolling process, the intermediate steel sheets of each test number were subjected to cold rolling using a reverse rolling mill to produce ferritic stainless steel foils with a foil body having a thickness of 10 μm. The maximum rolling reduction R2 in one pass for each test number was MAX (%) are shown in Table 2.

[0105] By the above manufacturing process, ferritic stainless steel foils with each test number were manufactured.

[0106] [About the evaluation test] The following evaluation tests were carried out on the produced ferritic stainless steel foils with each test number. (Test 1) Diffraction intensity measurement test (Test 2) Integrated intensity measurement test (Test 3) Corrosion resistance evaluation test Each test will be explained below.

[0107] [(Test 1) Diffraction Intensity Measurement Test] Based on the method described in the above [Method for measuring the diffraction intensity of each lattice plane], the diffraction intensity I of the {110} plane in the foil body of the ferritic stainless steel foil of each test number was measured. 110 , {200} plane diffraction intensity I 200 , and the diffraction intensity of the {211} plane I 211 The obtained I 110 , I 200 , and I 211 F1 was calculated based on the above. F1 for each test number is shown in Table 3.

[0108] [Table 3]

[0109] [(Test 2) Integrated intensity measurement test] Based on the method described in the above [Method for measuring the integrated intensity of each lattice plane], the integrated intensity II of the {110} plane from the depth position of 0.38 μm to the depth position of 2.82 μm in the foil body of the ferritic stainless steel foil of each test number 110 , and the integrated intensity of the {211} plane II 211 The obtained II 110 and II 211 Based on equation (1), I R Calculate I from the depth position of 0.38 μm to the depth position of 2.82 μm. R The maximum value of I MAX The I of each test number was calculated. MAX is shown in Table 3.

[0110] [(Test 3) Corrosion resistance evaluation test] The corrosion resistance of the ferritic stainless steel foil of each test number was evaluated by the following method. First, a circular test piece with a diameter of 11 mm was taken from the ferritic stainless steel foil. One surface of the test piece was used as the evaluation surface. The developed area ratio Sdr, as specified in ISO25178-2:2012, was measured on the evaluation surface of the test piece. The developed area ratio Sdr is an index that represents the rate of increase in the surface area of ​​the measured surface compared to a flat surface. Since the corrosion reaction begins on the surface of the foil itself, the greater the developed area ratio Sdr of the test piece, the faster the corrosion progresses.

[0111] The developed area ratio Sdr of the evaluation surface of the test specimen was measured using a laser microscope. The laser microscope used was a Keyence VK-X100. A measurement area of ​​280 μm × 200 μm was measured at a magnification of 2000x. Specifically, four locations within the measurement area were measured with a 145 μm × 109 μm field of view to measure the entire area, and a surface image was obtained. The four surface images were linked using the accompanying image linking software to obtain a surface image of the 280 μm × 200 μm measurement area. A reference plane was set by cutting 0.3% of the area from the low-brightness side from the surface shape profile obtained by analyzing the surface image of the measurement area, and a three-dimensional image was generated. Filtering was performed using a high-pass filter with a cutoff wavelength of 50 μm. A Gaussian filter was used for filtering. The developed area ratio Sdr, as defined in ISO25178-2:2012, was calculated in a 200 μm × 150 μm region of the obtained three-dimensional image.

[0112] Using the test specimens with the measured developed area ratio (Sdr), evaluation cells simulating sulfide-based all-solid-state batteries were fabricated. Specifically, 0.12 g of sulfide-based solid electrolyte was placed in a mold with an inner diameter of 11 mm and then pressurized at 300 MPa to form a cylindrical sulfide-based solid electrolyte pellet with a thickness of 700 μm and a bottom diameter of 11 mm. β-Li3PS4 was used as the sulfide-based solid electrolyte. The resulting pellet was placed on the evaluation surface of each test specimen. Furthermore, a cylindrical Li foil with a thickness of 1.2 mm and a bottom diameter of 11 mm was placed on top of the sulfide-based solid electrolyte pellet. These were placed in a measurement cell with an inner diameter of 11 mm, which was sealed from the outside air, and then bolted to a pressure of 5 MPa. The process from preparing the sulfide-based solid electrolyte pellet to sealing the evaluation cell was carried out in a glove box with an Ar atmosphere. The evaluation cells for each test specimen were fabricated using the above process.

[0113] Cyclic voltammetry (CV) measurements were carried out using the evaluation cells of each test number. In the cyclic voltammetry measurements, the test piece was used as the working electrode, and metal Li foil was used as the counter electrode and reference electrode. Specifically, the voltage was measured for the evaluation cell held at 60°C for 24 hours, and the open-circuit voltage V OC (V) to 3.0V, then to 0.005V, and again to the open circuit voltage V OC (V) and the current density (μA / cm 2 The open-circuit voltage V was measured at a sweep rate of 5 mV / sec. A series of voltage sweeps constituted one cycle, which was repeated five times. OC was 2.0 to 2.5 V for the evaluation cells of all test numbers.

[0114] Based on the measurement results, the open-circuit voltage V at the nth cycle (n is an integer between 1 and 5) OC The current density (μA / cm) flowing during the sweep from (V) to 3.0 V 2 ) was integrated by the time (seconds) it took to sweep. Furthermore, the integrated value was divided by the developed area ratio Sdr to eliminate the influence of minute irregularities on the evaluation surface of the test piece, and the result was calculated as C n (μC / cm2 ) is defined as C n (μC / cm 2 ) is the open circuit voltage V OC The time elapsed from the start of the sweep from (V) to 3.0V is defined as the test time t (seconds), and the time it takes to reach 3.0V is defined as t 3.0 (seconds), and the current density flowing through the evaluation cell at test time t (seconds) is I(t) (μA / cm 2 ) and the developed area ratio of the test piece is Sdr, it can be calculated using the following formula.

number

[0115] The sum of C1 to C5 is the integrated current value C (μC / cm 2 ) and was used as an index to represent the progress of the corrosion reaction on the test piece. 2 ) can be calculated using the following formula: C=C1+C2+C3+C4+C5 The integrated current value C (μC / cm 2 ) are shown in Table 3. When the integrated current value C is 7500 μC / cm 2 Super~8500μC / cm 2 When the integrated current value C was 7500 μC / cm, it was judged that excellent corrosion resistance was obtained. 2 When the integrated current value C was 8500 μC / cm or less, it was judged that even better corrosion resistance was obtained. 2 When the value exceeded this, it was determined that excellent corrosion resistance was not obtained.

[0116] [Evaluation results] Referring to Tables 1 to 3, in the ferritic stainless steel foils of test numbers 1 to 9, F1 satisfied formula (1), and therefore excellent corrosion resistance was obtained.

[0117] In the ferritic stainless steel foils of test numbers 1 to 6, I MAX was 15.0 or more, which resulted in even better corrosion resistance.

[0118] On the other hand, in test number 10, the maximum reduction rate R1 MAX (%) was too small. Therefore, F1 did not satisfy formula (1). As a result, excellent corrosion resistance was not obtained.

[0119] In test number 11, FA in the intermediate annealing step was too low, so F1 did not satisfy formula (1), and as a result, excellent corrosion resistance was not obtained.

[0120] The embodiments of the present disclosure have been described above. However, the above-described embodiments are merely examples for implementing the present disclosure. Therefore, the present disclosure is not limited to the above-described embodiments, and can be implemented by appropriately modifying the above-described embodiments within the scope of the present disclosure.

Claims

1. A foil body made of ferritic stainless steel, The diffraction intensity I of the {110} plane obtained by focusing X-ray diffraction measurement of the foil body １１０ and the diffraction intensity I of the {200} plane ２００ and the diffraction intensity I of the {211} plane ２１１ and satisfy the formula (1). Ferritic stainless steel foil. I １１０ / (I １１０ +I ２００ +I ２１１ )≦0.16 (1)

2. The ferritic stainless steel foil according to claim 1, further comprising: I defined by formula (2) in the region from a depth of 0.38 μm to a depth of 2.82 μm starting from the surface of the foil body Ｒ The maximum value of I ＭＡＸ is 15.0 or more, Ferritic stainless steel foil. I Ｒ =-- １１０ / -- ２１１ (2) Here, II in formula (2) １１０ is substituted with the integrated intensity of the {110} plane obtained by grazing incidence X-ray diffraction, and II ２１１ is substituted with the integrated intensity of the {211} plane obtained by grazing incidence X-ray diffraction.

3. The ferritic stainless steel foil according to claim 1, The chemical composition of the foil body is, in mass%, C: 0.001-0.030%, Si: 0.01-1.00%, Mn: 0.01-1.00%, P: 0.050% or less, S: 0.030% or less, Ni: 0.01-0.50%, Cr: 12.00-20.00%, Mo: 0.01-2.50%, N: 0-0.100%, Ti: 0 to 0.80%, Nb: 0 to 0.80%, and Zr: 0 to 0.80%; The balance consists of Fe and impurities. Ferritic stainless steel foil.

4. The ferritic stainless steel foil according to claim 2, The chemical composition of the foil body is, in mass%, C: 0.001-0.030%, Si: 0.01-1.00%, Mn: 0.01-1.00%, P: 0.050% or less, S: 0.030% or less, Ni: 0.01-0.50%, Cr: 12.00-20.00%, Mo: 0.01-2.50%, N: 0-0.100%, Ti: 0 to 0.80%, Nb: 0 to 0.80%, and Zr: 0 to 0.80%; The balance consists of Fe and impurities. Ferritic stainless steel foil.

5. The ferritic stainless steel foil according to any one of claims 1 to 4, an electrode mixture layer formed on the surface of the ferritic stainless steel foil, electrode.

6. The electrode according to claim 5; an electrolyte; battery.

7. 7. The battery of claim 6, The electrolyte is a sulfide-based solid electrolyte. battery.

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