Electrode foil for electrolytic capacitors and electrolytic capacitors

Abstract

An electrode foil for an electrolytic capacitor comprises a substrate containing a valve-acting metal and a dissimilar metal composite layer covering the surface of the substrate. The dissimilar metal composite layer includes a mixed region containing a first metal and a second metal different from the first metal. The mixed region constitutes at least 50% of the thickness of the dissimilar metal composite layer. The mixed region is used to achieve a content of at least 1 atom% for both the first metal (M1) and the second metal (M2) relative to the total metal content.

Description

Technical Field

[0001] This invention relates to electrode foil for electrolytic capacitors and electrolytic capacitors. Background Technology

[0002] The anode foil of an electrolytic capacitor can, for example, use a foil-shaped or plate-shaped substrate containing a valve-acting metal. To increase the capacitance of the electrolytic capacitor, the surface of the substrate typically has a porous portion. The porous portion is formed by etching the substrate. Through chemical conversion treatment of the substrate, the surface of the substrate (porous portion) is covered with a metal oxide (dielectric) layer.

[0003] However, as the performance of electronic devices equipped with electrolytic capacitors improves, there is a demand for higher performance electrolytic capacitors. For example, there is a need to improve the relative permittivity and voltage withstand capability of the dielectric layer. However, it is difficult to simultaneously improve the relative permittivity and voltage withstand capability with a single dielectric layer (metal oxide layer). As a method to simultaneously improve the relative permittivity and voltage withstand capability, one example is a method in which the dielectric layer consists of two layers: an oxide layer of a first metal that is beneficial for improving the relative permittivity and an oxide layer of a second metal that is different from the first metal and is beneficial for improving the voltage withstand capability.

[0004] Patent document 1 proposes to form a first metal oxide layer using a first precursor and a second metal oxide layer using an atomic layer deposition (ALD) method.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: U.S. Patent Application Publication No. 2017 / 0103883 Summary of the Invention

[0008] An electrode foil for an electrolytic capacitor according to one aspect of the present invention comprises a substrate including a valve-acting metal and a dissimilar metal composite layer covering the surface of the substrate. The dissimilar metal composite layer includes a mixed region containing a first metal and a second metal different from the first metal. The mixed region constitutes at least 50% of the thickness direction of the dissimilar metal composite layer. The content M1 of the first metal relative to all metals and the content M2 of the second metal relative to all metals in the mixed region are both 1 atom% or more.

[0009] Another aspect of the present invention provides an electrolytic capacitor comprising the aforementioned electrode foil for an electrolytic capacitor.

[0010] According to the present invention, high-performance and high-reliability electrolytic capacitors can be obtained. Attached Figure Description

[0011] Figure 1 This is a cross-sectional schematic diagram of the substrate of the electrode foil according to one embodiment of the present invention.

[0012] Figure 2 This is an enlarged cross-sectional schematic diagram showing a portion of the porous portion of an electrode foil whose surface is covered by a dissimilar metal composite layer, according to one embodiment of the present invention.

[0013] Figure 3 It is Figure 2 The X-section is shown as an enlarged cross-sectional diagram.

[0014] Figure 4 This is a magnified cross-sectional schematic diagram showing a portion of the porous portion of the electrode foil in another embodiment of the present invention, whose surface is covered by a dissimilar metal composite layer.

[0015] Figure 5 This is a schematic diagram of the cross-section of an electrolytic capacitor.

[0016] Figure 6 It is a three-dimensional diagram schematically showing the structure of the winding body of an electrolytic capacitor. Detailed Implementation

[0017] Before describing the implementation methods, the issues in the prior art are briefly described below.

[0018] When a dielectric layer is obtained by forming multiple metal oxide layers using multiple precursors via the ALD method, the increased quantity of precursors supplied to the reaction chamber and the increased number of cycles (precursor cycles) result in an increased amount of impurities from the precursors contained in the dielectric layer. Consequently, leakage current may sometimes increase.

[0019] In the case of a double-layer dielectric layer, the uneven distribution of the two metals along the thickness direction of the dielectric layer can sometimes prevent the stable acquisition of the electrode foil performance resulting from the two metals. For example, sometimes the presence of metal oxides with poor insulation is greater than the target value in certain areas, leading to reduced insulation and increased leakage current.

[0020] One method involves heat-treating a laminate of a first metal oxide layer and a second metal oxide layer to form a composite layer in which the first and second metal oxides coexist. However, heat treatment requires heating the laminate at temperatures above 450°C, which can sometimes cause the substrate to deteriorate or deform due to the heat. It is also difficult to heat the laminate uniformly, resulting in significant variations in the degree of heating along the thickness of the porous portion. Therefore, it is difficult to adjust the ratio and distribution of the first and second metals, making it impossible to consistently obtain the performance of the electrode foil.

[0021] One method involves forming an oxide layer of a second metal, different from the first metal contained in the substrate, on the surface of a substrate, performing a chemical conversion treatment on the substrate, and forming a first metal oxide layer between the substrate and the second metal oxide layer. In this method, a region where the first and second metal oxides coexist can be formed at the boundary between the first and second metal oxide layers. However, in this chemical conversion treatment method, this region is formed with a thickness extremely thin compared to the first and second metal oxide layers. Furthermore, it is difficult to adjust the ratio and distribution of the first and second metals. Therefore, it is impossible to consistently obtain stable electrode foil performance.

[0022] When a substrate with two metal oxide layers (a first metal oxide layer and a second metal oxide layer) formed on its surface is chemically converted to repair defects in the two layers, the metals contained in the two layers cause deviations in the degree of repair, and sometimes the performance of the electrode foil cannot be stably obtained.

[0023] In view of the above-mentioned problems, the present invention provides an electrode foil for electrolytic capacitors, which is used to provide high-performance and high-reliability electrolytic capacitors.

[0024] The electrode foil for the electrolytic capacitor of this embodiment includes a substrate comprising a valve-acting metal and a dissimilar metal composite layer covering the surface of the substrate. The dissimilar metal composite layer includes a mixed region comprising a first metal and a second metal different from the first metal, the mixed region constituting at least 50% of the thickness direction of the dissimilar metal composite layer. The content percentage M1 of the first metal relative to all metals and the content percentage M2 of the second metal relative to all metals in the mixed region are both 1 atom% or more.

[0025] The aforementioned dissimilar metal composite layer can be formed by atomic layer deposition (ALD) using a precursor containing a first metal and a precursor containing a second metal, or a single precursor containing both the first and second metals, depositing the first and second metals at atomic layer units. Therefore, regions where the first and second metals coexist can be easily formed with a suitable thickness, and the ratio and distribution of the first and second metals can be easily adjusted. In the coexisting regions, the first and second metals can be uniformly distributed along the thickness direction of the dissimilar metal composite layer. In the case of ALD, the effects of heat from the substrate are also mitigated. When chemically converting a substrate with a dissimilar metal composite layer on its surface to repair defects in the dissimilar metal composite layer, deviations in the degree of repair are suppressed due to the coexistence of the first and second metals. Furthermore, using a single precursor containing both the first and second metals reduces the amount of precursor supplied to the reaction chamber and the number of cycles (precursor cycles), thus reducing impurities from the precursor. Therefore, the increase in leakage current caused by the increased amount of impurities from the precursor is suppressed. Based on the above, the performance of the electrode foil derived from the first and second metals can be stably obtained, leading to a high-performance and highly reliable electrolytic capacitor.

[0026] The dissimilar metal composite layer includes at least the aforementioned mixed regions, and may also include regions other than the mixed regions. Regions other than the mixed regions include: regions containing the first metal but not the second metal, and regions containing the second metal but not the first metal. The first metal and / or the second metal may be the same as or different from the valve-acting metal contained in the substrate. The dissimilar metal composite layer may further include a third metal other than the first and second metals. The third metal may be included in the mixed regions or in regions other than the mixed regions.

[0027] The ratio of the thickness of the mixed-use region to the thickness of the dissimilar metal composite layer is 50% or more, it can be 70% or more, or it can be 90% or more. Alternatively, the ratio can be 100%. That is, the entire dissimilar metal composite layer can be composed of the mixed-use region. It should be noted that the thickness of the mixed-use region refers to the thickness of the dissimilar metal composite layer within the mixed-use region in the thickness direction.

[0028] When the content of the first metal relative to all metals, M1, and the content of the second metal relative to all metals, M2, in the mixed storage region are both 1 atomic% or more, the performance of the electrode foil brought about by the first metal and the second metal is fully utilized. The content of the first metal relative to all metals, M1, and the content of the second metal relative to all metals, M2, in the mixed storage region can be 1 atomic% or more and 99 atomic% or less, or 1 atomic% or more and 70 atomic% or less.

[0029] The mixed region can be divided into three equal parts, A1, A2, and A3, along the thickness direction of the dissimilar metal composite layer, starting from the surface side of the composite layer. Preferably, the first metal and the second metal are uniformly distributed within regions A1 to A3. In this case, the electrode foil properties resulting from each metal can be easily and stably obtained, leading to high-performance and high-reliability electrolytic capacitors.

[0030] Within the A1 to A3 regions, it is preferable that the deviation in the atomic ratio of the first metal to the second metal is small. Specifically, in the A1 region, the atomic ratio R of the first metal to the second metal is... A1 The ratio of the number of atoms of the first metal to the second metal in region A2, R A2 And the atomic ratio R of the first metal to the second metal in region A3. A3 Preferably, 0.8 ≤ R A2 / R A1 ≤1.2 and 0.8≤R A3 / R A2 A relationship ≤1.2. More preferably, R. A2 / R A1 and R A3 / R A2 They are above 0.9 and below 1.1, respectively.

[0031] Within the regions A1 to A3, it is preferable to have a small deviation in the content of the first metal relative to all metals. Specifically, the content M1 of the first metal relative to all metals in region A1 is... A1 (atomic %), the percentage of the first metal in region A2 relative to all metals, M1 A2 (atomic percentage), and the content M1 of the first metal in region A3 relative to all metals. A3 (atomic percentage) preferably satisfies 0.9 ≤ M1 A2 / M1 A1 ≤1.1 and 0.9≤M1 A3 / M1 A2 The relationship is ≤1.1. Furthermore, M1 A1 M1 A2 and M1 A3 Each is preferably 1 atom% or more.

[0032] Within the regions A1 to A3, it is preferable to have a small deviation in the content of the second metal relative to all metals. Specifically, the content of the second metal relative to all metals in region A1 is M2. A1 (atomic %), the content of the second metal in region A2 relative to all metals, M2 A2 (atomic %) and the content of the second metal in region A3 relative to all metals, M2 A3(Atomic percentage) preferably satisfies 0.9 ≤ M2 A2 / M2 A1 ≤1.1 and 0.9≤M2 A3 / M2 A2 The relationship is ≤1.1. Furthermore, M2 A1 M2 A2 and M2 A3 Each is preferably 1 atom% or more.

[0033] The substrate may have a porous portion and a core continuous with the porous portion, and a dissimilar metal composite layer may cover the surface of the porous portion. The substrate is an integral part of the core and the porous portion. The substrate may be a metal foil containing a valve-acting metal. The substrate is obtained, for example, by etching the metal foil. The porous portion is the surface side (outer side) of the metal foil that has been porousened by etching, and the remaining portion, which is the inner side of the metal foil, is the core. The porous portion has pits or pores surrounded by a metal skeleton containing a valve-acting metal. The dissimilar metal composite layer is provided in such a way that it covers at least a portion of the surface of the metal skeleton constituting the porous portion (the metal skeleton surrounding the pits or pores).

[0034] (Metal 1 to Metal 3)

[0035] From the viewpoint of improving the relative permittivity of the dielectric layer, the first metal preferably includes at least one selected from titanium (Ti), tantalum (Ta), hafnium (Hf), zirconium (Zr) and zinc (Zn).

[0036] The first metal preferably includes at least one selected from titanium and tantalum (hereinafter referred to as titanium, etc.). Titanium, etc., is beneficial for improving corrosion resistance and insulation, enabling high performance and long lifespan of electrolytic capacitors. Deterioration and short circuits in electrolytic capacitors tend to occur on the surface side of the porous portion; therefore, titanium, etc., can be included in greater quantities on the surface side of the porous portion. In the case of titanium, especially for electrolytic capacitors with low rated voltage, it is easy to obtain effects such as improved insulation.

[0037] The second metal preferably comprises at least one selected from silicon (Si) and aluminum (Al) (hereinafter referred to as silicon, etc.). Silicon, etc., is beneficial for improving the voltage withstand capability of the dielectric layer. In addition, silicon, etc., is also beneficial for improving insulation. Silicon, etc., can be contained in greater quantities in the core side of the porous portion of the dielectric layer, which is prone to defects.

[0038] The content of the first metal and the second metal in the dissimilar metal composite layer is varied along the thickness direction of the porous portion. Depending on the application of the electrolytic capacitor, the required performance (voltage withstand, capacitance, etc.), and the metallic properties of the first and second metals selected, the first metal can be increased on the surface side of the porous portion, or the second metal can be increased on the core side of the porous portion. Alternatively, the second metal can be increased on the surface side of the porous portion, or the first metal can be increased on the core side of the porous portion.

[0039] Preferably, the first metal is titanium and the second metal is silicon, and the silicon content in the mixed region is between 1 atomic% and 70 atomic% relative to the total metal content. In this case, it is easy to simultaneously obtain improvements in the relative permittivity and voltage withstand capability of the dielectric layer. The ALD method can be used to increase the silicon content, which is beneficial for improving voltage withstand capability, on the core side of the porous portion where defects in the dielectric layer are prone to occur. On the surface side of the porous portion where the substrate is prone to corrosion, the titanium content, which is beneficial for improving corrosion resistance, can be increased. Therefore, the performance of the electrode foil can be improved more effectively.

[0040] Preferably, the first metal is titanium and the second metal is aluminum, and the aluminum content in the mixed region is between 1 atomic% and 55 atomic% relative to the total metal content. In this case, it is easy to simultaneously obtain improvements in the relative permittivity and voltage withstand capability of the dielectric layer. The ALD method can be used to increase the aluminum content, which is beneficial for improving voltage withstand capability, on the core side of the porous portion where defects in the dielectric layer are prone to occur. On the surface side of the porous portion of the substrate where corrosion is likely to occur, the titanium content, which is beneficial for improving corrosion resistance, can be increased. Therefore, the performance of the electrode foil can be improved more effectively.

[0041] From the viewpoint of further improving the dielectric constant, Zr can also be used together with Ti as the first metal. From the viewpoint of further improving the withstand voltage, Al can also be used together with Si as the second metal.

[0042] Examples of third metals include niobium (Nb). Nb is beneficial for increasing the relative permittivity of the dielectric layer.

[0043] (Anode foil)

[0044] The dissimilar metal composite layer can be an oxide layer. In this case, the oxide layer functions as a dielectric layer, and the electrode foil can be used as an anode foil. By using a metal that is beneficial to improving the relative permittivity of the dielectric layer in the first metal and a metal that is beneficial to improving the voltage withstand capability of the dielectric layer in the second metal, both the relative permittivity and voltage withstand capability of the dielectric layer can be improved simultaneously. In the case of an anode foil, the mixed region can contain the first metal and the second metal in the form of an oxide of the first metal and an oxide of the second metal, or a composite oxide of the first metal and the second metal.

[0045] The mixed storage region may contain impurities. The impurities are at least one selected from hydrogen, carbon, and nitrogen. The precursor used in the ALD method may contain the aforementioned impurities. The impurity content Mi in the mixed storage region is preferably 25 atomic percent or less, more preferably 15 atomic percent or less, relative to the total of all metals and impurities in the mixed storage region. When the dissimilar metal composite layer is an oxide layer (dielectric layer) and the electrode foil is used as the anode foil, a high impurity content may sometimes increase the leakage current. When using a precursor containing both a first metal and a second metal, the impurity content can be easily reduced to the aforementioned range, and the increase in leakage current caused by impurities can be easily suppressed. In particular, the hydrogen content in the mixed storage region is suppressed to 10 atomic percent or less, relative to the total of all metals and impurities in the mixed storage region.

[0046] (Cathode foil)

[0047] The dissimilar metal composite layer can be a conductive layer. In this case, the electrode foil can be used as the cathode foil. Metals that improve corrosion resistance and conductivity can be combined in the first and second metals. For example, titanium and tantalum can be combined. This approach is advantageous in terms of increased productivity and reduced manufacturing costs.

[0048] From the viewpoint of improving the conductivity of the conductive layer, the dissimilar metal composite layer (conductive layer) can further include conductive carbon. The dissimilar metal composite layer can include regions where a first metal, a second metal, and conductive carbon coexist. The percentage of conductive carbon in the coexisting regions relative to the total content of all metals and conductive carbon can, for example, be 10 atomic% or more and 95 atomic% or less. Alternatively, the dissimilar metal composite layer can be composed of a region where the first metal and the second metal coexist (coexisting layer) and a conductive carbon layer.

[0049] Here, Figure 1 This is a schematic cross-sectional view of the substrate of an electrode foil according to one embodiment of the present invention. Figure 2 This is a magnified cross-sectional schematic diagram showing a portion of the porous portion having a dissimilar metal composite layer in an electrode foil according to one embodiment of the present invention. Figure 3 It is Figure 2The X-section is shown as an enlarged cross-sectional diagram.

[0050] The electrode foil 10 includes a substrate 110 containing a valve-acting metal and a dissimilar metal composite layer 120 (first layer 121) covering the surface of the substrate 110. The substrate 110 has a porous portion 112 and a core portion 111 continuous with the porous portion 112. The substrate 110 is an integral part of the core portion 111 and the porous portion 112. Figure 2 As shown, a dissimilar metal composite layer 120 covers the surface of the porous portion 112. The porous portion 112 has a plurality of pits (pores) P surrounded by a metal skeleton containing a valve-acting metal. The dissimilar metal composite layer 120 covers the surface of the metal skeleton of the porous portion 112. That is, the dissimilar metal composite layer 120 covers the outer surface of the porous portion 112 and the inner wall surface of the pits (pores) P.

[0051] The entire dissimilar metal composite layer 120 is composed of a mixed region consisting of a first metal and a second metal different from the first metal. The dissimilar metal composite layer (mixed region) 120 has a thickness T1. In this embodiment, the entire dissimilar metal composite layer is composed of the mixed region, but the mixed region only needs to constitute more than 50% of the thickness of the dissimilar metal composite layer.

[0052] like Figure 1 As shown, the porous portion 112 can be divided into three equal regions, B1, B2, and B3, in the thickness direction from the side opposite to the core 111. That is, when the thickness of the porous portion 112 is set to T, regions B1 to B3 each have a thickness of 1 / 3T. It should be noted that the thickness T of the porous portion 112 is obtained by cutting the electrode foil 10 to obtain a cross-section in the thickness direction of the core 111 and the porous portion 112, obtaining an image of the cross-section based on a scanning electron microscope (SEM), and calculating the average thickness of any 10 points of the porous portion.

[0053] The content M1 of the first metal relative to all metals in region B1. B1 (atomic %), the content of the first metal in region B2 relative to all metals, M1 B2 (atomic %) and the content of the first metal in region B3 relative to all metals, M1 B3 (atomic percentage) satisfies 1 ≤ (M1) B1 +M1 B2 +M1 B3 The relationship is ) / 3. It should be noted that the content of the first metal in region B1 relative to all metals refers to the content of the first metal in region B1 relative to all metals in the mixed region covering the porous surface. The content of the first metal in region B2 relative to all metals and the content of the first metal in region B3 relative to all metals are the same.

[0054] The content of the second metal relative to all metals in region B1, M2 B1 (atomic %), the content of the second metal in region B2 relative to all metals, M2 B2 (atomic %) and the content of the second metal in region B3 relative to all metals, M2 B3 (atomic percentage) satisfies 1 ≤ (M2) B1 +M2 B2 +M2 B3 The relationship is ) / 3. It should be noted that the content of the second metal in region B1 relative to all metals refers to the content of the second metal in region B1 relative to all metals in the mixed region covering the porous surface. The content of the second metal in region B2 relative to all metals and the content of the second metal in region B3 relative to all metals are the same.

[0055] In the thickness direction (regions B1 to B3) of the porous portion 112, the content of the first metal and the second metal in the mixed region covering the surface of the porous portion can be varied. For example, compared to the core side (region B3) of the porous portion, the content of the metal that is beneficial to improving corrosion resistance as the first metal can be increased on the surface side (region B1). Alternatively, compared to the surface side (region B1) of the porous portion, the content of the metal that is beneficial to improving voltage resistance as the second metal can be increased on the core side (region B3).

[0056] The atomic ratio R of the first metal to the second metal in region B1. B1 The ratio of the number of atoms of the first metal to the second metal in region B2, R B2 The ratio of the number of atoms of the first metal to the second metal in region B3, R B3 It can satisfy R B3 <R B2 <R B1 The relationship is as follows. It should be noted that the atomic ratio of the first metal to the second metal in region B1 refers to the atomic ratio of the first metal in region B1 to the second metal in the mixed region covering the porous surface. The atomic ratios of the first metal to the second metal in regions B2 and B3 are also the same. R B2 / R B1 and R B3 / R B2 The values ​​can be above 0.05 and below 0.95, above 0.1 and below 0.75, or above 0.15 and below 0.65.

[0057] It could be M1 B3 <M1B2 <M1 B1 M1 B2 / M1 B1 and M1 B3 / M1 B2 The values ​​can be above 0.05 and below 0.95, above 0.1 and below 0.75, or above 0.15 and below 0.65.

[0058] It can be M2 B1 <M2 B2 <M2 B3 M2 B2 / M2 B3 and M2 B1 / M2 B2 The values ​​can be above 0.05 and below 0.95, above 0.1 and below 0.75, or above 0.15 and below 0.65.

[0059] like Figure 3 As shown, the mixed region (dissimilar metal composite layer 120) can be divided into three equal regions, A1, A2, and A3, in the direction of thickness T1 of the dissimilar metal composite layer 120, starting from the surface side of the dissimilar metal composite layer 120. Preferably, in any of the regions B1 to B3, the distribution deviation of the first metal and the second metal between regions A1 to A3 is small. In this case, the electrode foil performance brought about by each metal can be easily and stably obtained, and a high-performance and high-reliability electrolytic capacitor can be easily obtained.

[0060] In any region of region B1 to B3, the deviation of the atomic ratio of the first metal to the second metal is preferably small in regions A1 to A3. A2 / R A1 and R A3 / R A2 The values ​​are preferably 0.8 or more and 1.2 or less, and more preferably 0.9 or more and 1.1 or less.

[0061] In any region from B1 to B3, the deviation of the content of the first metal relative to all metals is preferably small in regions from A1 to A3, M1 A2 / M1 A1 and M1 A3 / M1 A2 The values ​​are preferably 0.9 or higher and 1.1 or lower. Preferably, at least in region B1, M1 A1 M1 A2 and M1 A3 Each is more than 1 atom%.

[0062] In any region of B1 to B3, and within regions A1 to A3, the deviation of the content of the second metal relative to all metals is preferably small, M2 A2 / M2 A1 and M2 A3 / M2 A2 The values ​​are preferably 0.9 or higher and 1.1 or lower. Preferably, at least in region B3, M2 A1 M2 A2 and M2 A3 Each is more than 1 atom%.

[0063] Analysis of the distribution and concentration of each element in the mixed storage region can be performed using elemental mapping based on energy dispersive X-ray spectroscopy (EDX).

[0064] The content of the first and second metals in the mixed storage area can be determined by the following method.

[0065] The electrode foil was cut to obtain a cross-section in the thickness direction of the porous portion, resulting in a sample cross-section. The sample cross-section was observed using a scanning electron microscope (SEM) to confirm the dissimilar metal composite layer covering the surface of the porous portion. EDX-based elemental mapping was performed on the dissimilar metal composite layer to identify the mixed regions of the first and second metals. The content of the first metal (M1) and the content of the second metal (M2) in the mixed regions were then calculated.

[0066] Specifically, using SEM images of the sample cross-section, the porous material was divided into regions B1 to B3. The content of the first metal at any 10 locations within the mixed regions covering region B1 was calculated, and their average value was taken as the content M1 of the first metal in the mixed regions within region B1. B1 The content M1 of the first metal in the mixed storage area of ​​region B2. B2 The content of the first metal in the mixed storage area of ​​region B3, M1 B3 Similarly, calculate M1. B1 ~M1 B3 The average value is taken as the content M1 of the first metal in the mixed storage area.

[0067] In addition, the content of the second metal at any 10 locations in the mixed storage area covering region B1 is calculated, and their average value is taken as the content M2 of the second metal in the mixed storage area of ​​region B1. B1 The content of the second metal in the mixed storage area of ​​region B2, M2 B2 The content of the second metal in the mixed storage area of ​​region B3, M2 B3 Similarly, calculate M2. B1 ~M2 B3The average value is taken as the content M2 of the second metal in the mixed storage area.

[0068] R B1 R B2 and R B3 By calculating M1 respectively B1 / M2 B1 M1 B2 / M2 B2 and M1 B3 / M2 B3 And that will give you the answer.

[0069] The content of impurities (H, C, N) in the mixed storage area can be determined by the following method.

[0070] Find the impurity content at any 10 locations in the mixed region covering the surface of region B1, and calculate their average value as the impurity content Mi in the mixed region of region B1. B1 The impurity content Mi in the mixed storage area of ​​region B2. B2 The impurity content Mi in the mixed storage area of ​​region B3 B3 Similarly, calculate Mi. B1 ~Mi B3 The average value is taken as the impurity content Mi in the mixed storage area.

[0071] The content of the first and second metals in regions A1 to A3 can be determined by the following method.

[0072] Using SEM images of the sample cross-section, any region from B1 to B3 is selected. The mixed region covering the selected region is further subdivided into regions A1 to A3. Elemental mapping based on EDX analysis is performed to determine the content of the first and second metals in regions A1 to A3. Specifically, the content of the first metal at any 10 locations in region A1 is calculated, and their average value is taken as the content M1 of the first metal in region A1. A1 The content of the first metal in region A2, M1 A2 The content of the first metal in region A3, M1 A3 Similarly, calculate the content of the second metal at any 10 locations in region A1, and take their average as the content M2 of the second metal in region A1. A1 The content of the second metal in region A2, M2 A2 The content of the second metal in region A3, M2 A3 Similarly, find the answer.

[0073] R A1 R A2 and RA3 By calculating M1 respectively A1 / M2 A1 M1 A2 / M2 A2 and M1 A3 / M2 A3 And that will give you the answer.

[0074] (Level 2)

[0075] From the viewpoint of further improving the performance of the electrode foil, the electrode foil may have a layer (second layer) containing an oxide of a valve-acting metal between the substrate and the dissimilar metal composite layer (first layer). The second layer can be formed by performing a chemical conversion treatment on the electrode foil having the first layer on its surface. The thickness of the second layer can be controlled by applying a voltage to the electrode foil.

[0076] In the case of an anode foil where the first layer is an oxide layer, defects in the first layer are repaired through chemical conversion treatment (formation of the second layer), further improving the properties of the anode foil, such as voltage withstand capability. By mixing the first metal and the second metal, deviations in the degree of repair are suppressed. Defects in the first layer may occur, for example, during the manufacturing process of electrolytic capacitors, such as in the cutting process of the metal foil or the formation process of the winding body. The substrate preferably contains a valve-acting metal (e.g., Al) suitable for chemical conversion.

[0077] When the first layer is a conductive layer on the cathode foil, the formation of the second layer suppresses the reaction between the substrate and the electrolyte, thus inhibiting the degradation of the cathode foil. Furthermore, when a chemical conversion coating (second layer) is formed, capacitance may also be generated on the cathode side. If capacitance is generated on the cathode side in addition to the anode, the overall capacitance (combined capacitance) of the electrolytic capacitor decreases. However, by forming an oxide coating (second layer) of appropriate thickness on the roughened cathode foil, the capacitance on the cathode side is intentionally increased, and the decrease in the overall capacitance of the electrolytic capacitor can be suppressed. When using an electrode foil as the cathode foil, a thinner chemical conversion coating is preferred.

[0078] Here, Figure 4 This is a magnified cross-sectional schematic diagram showing a portion of the porous portion of the electrode foil in another embodiment of the present invention, whose surface is covered by a dissimilar metal composite layer.

[0079] like Figure 4 As shown, in the electrode foil 10, a second layer 122 of thickness T2 can be formed between the metal skeleton constituting the porous portion 112 and the first layer 121 of thickness T1. The second layer is an oxide layer of the valve-acting metal from the substrate 110.

[0080] The thickness T1 of the first layer can be greater than the thickness T2 of the second layer. When the first layer is formed using the ALD method, it is also easy to adjust T2 < T1 in the B3 region deep within the pit. In the case of an anode foil, it is easy to simultaneously improve the relative permittivity and withstand voltage of the dielectric layer resulting from the first layer. In the case of a cathode foil, it is possible to reduce the impact of the cathode-side capacitance resulting from the second layer on the overall capacitance of the electrolytic capacitor. T1 / T2 can be 2 or more, or even 3 or more.

[0081] In the case of an anode foil, the thickness T1 of the dissimilar metal composite layer (first layer) can be 100 nm or more and 50,000 nm or less, or 500 nm or more and 30,000 nm or less. The thickness T2 of the second layer can be 500 nm or more and 30,000 nm or less, or 1,000 nm or more and 35,000 nm or less.

[0082] In the case of a cathode foil, the thickness T1 of the dissimilar metal composite layer (first layer) can be 20 nm or more and 20,000 nm or less, or 50 nm or more and 10,000 nm or less. The thickness T2 of the second layer can be 25 nm or more and 25,000 nm or less, or 50 nm or more and 20,000 nm or less.

[0083] It should be noted that the thickness T1 of the first layer is calculated as follows: the electrode foil is cut to obtain a cross-section in the thickness direction of the porous part, an SEM image of the cross-section is obtained, the thickness is measured at arbitrarily selected 10 points, and these measured values ​​are averaged to obtain the thickness. The thickness T2 of the second layer is also calculated using the same steps as the first layer.

[0084] The thickness of the porous portion is not particularly limited and can be appropriately selected based on the application of the electrolytic capacitor and the required voltage withstand capability. For example, the thickness of the porous portion can be selected in the range of 10 μm or more and 160 μm or less. Alternatively, the thickness of the porous portion can be set to be, for example, more than 1 / 10 and less than 5 / 10 of the thickness of the substrate.

[0085] The peak value of the fine pore diameter of the pits or pores in the porous material is not particularly limited. From the viewpoint of increasing the surface area and forming the dissimilar metal composite layer to the depth of the porous material, it can be set to, for example, 50 nm or more and 2000 nm or less, or 100 nm or more and 300 nm or less. The peak value of the fine pore diameter is, for example, the highest frequency pore diameter of the fine pore diameter distribution on a volume basis as measured using a mercury porosimeter.

[0086] The withstand voltage of an electrolytic capacitor is not particularly limited. For example, it can have a relatively low withstand voltage of 1V or more but less than 4V, or a relatively high withstand voltage of 4V or more, 15V or more, or 100V or more. When obtaining an electrolytic capacitor with a withstand voltage of 4V or more, it is preferable to set the thickness of the dissimilar metal composite layer, which functions as the dielectric layer, to be 4nm or more. Furthermore, when obtaining an electrolytic capacitor with a withstand voltage of 15V or more, it is preferable to set the thickness of the dissimilar metal composite layer, which functions as the dielectric layer, to be 21nm or more.

[0087] More specifically, for example, in the case of obtaining an electrolytic capacitor with a large withstand voltage of 60V or more, the peak value of the fine pore size of the porous part can be, for example, 50nm or more and 300nm or less, the thickness of the porous part can be, for example, 30μm or more and 160μm or less, and the thickness of the dissimilar metal composite layer that functions as a dielectric layer can be, for example, 30nm or more and 100nm or less.

[0088] In the case of electrolytic capacitors with electrode foil withstand voltages of, for example, 100V or higher, the shape of the etched pits can be a generally columnar, conical, or frustum-shaped form with a larger pit diameter on the surface side of the substrate and a smaller pit diameter on the core side, extending in a tunnel-like manner from the surface side of the substrate toward the core side. A portion of the columnar pit can penetrate the substrate.

[0089] In the case of obtaining an electrolytic capacitor with a relatively low withstand voltage, for example, a withstand voltage of 10V or less, the peak value of the fine pore size of the porous part can be, for example, 20nm or more and 200nm or less, the thickness of the porous part can be, for example, 30μm or more and 160μm or less, and the thickness of the dissimilar metal composite layer that functions as the dielectric layer can be, for example, 4nm or more and 30nm or less.

[0090] (Method for manufacturing electrode foil)

[0091] The method for manufacturing electrode foil includes, for example, a first step of preparing a substrate having a porous portion and a core continuous with the porous portion; and a second step of forming a dissimilar metal composite layer covering the surface of the metal skeleton constituting the porous portion.

[0092] (Step 1)

[0093] In the first step of preparing the substrate, for example, the metal foil containing the valve-acting metal is roughened by etching. Roughening forms a porous portion with multiple pits or pores on the surface side of the metal foil. Simultaneously, a core integral with the porous portion is formed on the inner side of the metal foil. Etching can be performed, for example, by direct current etching using direct current or alternating current etching using alternating current.

[0094] The valve-acting metal is not particularly limited; examples include aluminum (Al), tantalum (Ta), and niobium (Nb), which are easily formed into a second layer through chemical conversion treatment. The thickness of the metal foil is not particularly limited, for example, it can be 15 μm or more and 300 μm or less. The valve-acting metal can be contained in the substrate in the form of an alloy or compound containing the valve-acting metal.

[0095] (Step 2)

[0096] The formation of dissimilar metal composite layers can be achieved, for example, using vapor phase methods. Examples of vapor phase methods include vacuum evaporation, chemical vapor deposition, mist deposition, sputtering, pulsed laser deposition, and atomic layer deposition (ALD). Among these, ALD is superior in its ability to form dense dissimilar metal composite layers deep into porous regions.

[0097] In the ALD process, a feed gas is supplied to a reaction chamber containing the target material, enabling the formation of a heterogeneous element composite layer on the surface of the target material. The feed gas can be a gas containing precursors of a first metal and a second metal, or a gas containing precursors of both the first and second metals. In the ALD process, a self-limiting mechanism functions, thus the first and second metals are deposited on the surface of the target material in atomic-layer units. Therefore, the thickness of the formed heterogeneous element composite layer can be easily controlled in the ALD process. The thickness of the heterogeneous metal composite layer is controlled by the number of times the feed gas is supplied to the reaction chamber (cycle number).

[0098] In the ALD method, by depositing the first metal and the second metal on the surface of the object in atomic layer units, it is easy to form a layer in which the first metal and the second metal coexist, and it is easy to adjust the content of the first metal and the second metal. In the ALD method, the first metal and the second metal can be uniformly distributed in the thickness direction (A1 to A3 region) of the dissimilar metal composite layer.

[0099] When a dissimilar metal composite layer is formed in the form of an oxide layer, the following process (i) can be repeated as one cycle.

[0100] Process (i): Supply of gas containing precursors of the first metal and the second metal → Exhaust (purge) of gas containing precursors of the first metal and the second metal → Supply of oxidant → Exhaust (purge) of oxidant

[0101] Process (i) is repeated to deposit the first metal and the second metal in atomic layer units, thereby forming a heterogeneous metal composite layer (oxide layer) in which the first metal and the second metal coexist.

[0102] In addition, when a dissimilar metal composite layer is formed in the form of an oxide layer, the following process (ii) can be repeated as one cycle.

[0103] Process (ii): Supply of gas containing the precursor of the first metal → Exhaust (purge) of gas containing the precursor of the first metal → Supply of oxidant → Exhaust (purge) of oxidant → Supply of gas containing the precursor of the second metal → Exhaust (purge) of gas containing the precursor of the second metal → Supply of oxidant → Exhaust (purge) of oxidant

[0104] Process (ii) is repeated to deposit the first metal and the second metal alternately in atomic layer units, thereby forming a heterogeneous metal composite layer (oxide layer) in which the first metal and the second metal coexist.

[0105] In addition, when a dissimilar metal composite layer is formed in the form of an oxide layer, the following process (iii) can be repeated as one cycle.

[0106] Step (iii): Supply of gas containing the precursor of the first metal → Exhausting (purging) gas containing the precursor of the first metal → Supply of gas containing the precursor of the second metal → Exhausting (purging) gas containing the precursor of the second metal → Supply of oxidant → Exhausting (purging) oxidant

[0107] Process (iii) is repeated to deposit the first metal and the second metal alternately in atomic layer units, thereby forming a heterogeneous metal composite layer (oxide layer) in which the first metal and the second metal coexist.

[0108] When forming a dissimilar metal composite layer as a conductive layer, the following process (iv) can be repeated as one cycle.

[0109] Process (iv): Supply of gas containing precursors of the first metal and the second metal → Exhausting (purging) of gas containing precursors of the first metal and the second metal.

[0110] The process (iv) is repeated to deposit the first metal and the second metal in atomic layer units, thereby forming a heterogeneous metal composite layer (conductive layer) in which the first metal and the second metal coexist.

[0111] In addition, when forming a dissimilar metal composite layer as a conductive layer, the following process (v) can be repeated as one cycle.

[0112] Process (v): Supply of gas containing the precursor of the first metal → Exhausting (purging) gas containing the precursor of the first metal → Supply of gas containing the precursor of the second metal → Exhausting (purging) gas containing the precursor of the second metal

[0113] The process (v) is repeated to deposit the first metal and the second metal alternately at atomic layer units, thereby forming a heterogeneous metal composite layer (conductive layer) in which the first metal and the second metal coexist.

[0114] In steps (i) and (iv), a single precursor can be used to efficiently form the target dissimilar metal composite layer with fewer cycles. Therefore, the impurity content from the precursor in the dissimilar metal composite layer can be reduced.

[0115] Furthermore, in processes (i) and (vi), the content of the first and second metals in the thickness direction (regions B1 to B3) of the porous portion can be varied by utilizing the difference in the intrusion rate of the metals contained in the precursor into the pits. One of the first and second metals can be a metal with a slow intrusion rate into the pits (e.g., Ti, Ta), and the other of the first and second metals can be a metal with a fast intrusion rate into the pits (e.g., Si). In this case, the content of one of the first and second metals can be increased on the surface side (region B1) of the porous portion, and the content of the other of the first and second metals can be increased on the core side (region B3) of the porous portion.

[0116] In steps (ii), (iii), and (v), the content of the first and second metals in the thickness direction (regions B1 to B3) of the porous portion can be varied by utilizing the difference in the film formation rates (the penetration rates of the precursor containing the first metal and the precursor containing the second metal into the pit) of the two films formed alternately in atomic layer units by the ALD method. With a high film formation rate, the film easily forms deep into the pit; with a slow film formation rate, it is difficult to form a film deep into the pit. For example, one of the first and second metals can be a metal with a slow film formation rate (e.g., Ti, Ta), and the other can be a metal with a fast film formation rate (e.g., Si). In this case, the content of one of the first and second metals can be increased on the surface side (region B1) of the porous portion, and the content of the other of the first and second metals can be increased on the core side (region B3) of the porous portion.

[0117] Furthermore, in steps (ii), (iii), and (v), the adsorption time of the first metal (the supply time of the gas containing the precursor of the first metal) can be adjusted to change the content of the first metal and the second metal in the thickness direction (regions B1 to B3) of the porous portion. For example, the adsorption time of the first metal (the supply time of the gas containing the precursor of the first metal) can be shortened, causing the first metal to be adsorbed on the surface side of the porous portion, forming an unadsorbed portion of the first metal on the core side of the porous portion, and allowing the second metal to form a film on this adsorbed portion. In this case, the content of the first metal can be increased on the surface side of the porous portion, and the content of the second metal can be increased on the core side of the porous portion.

[0118] It should be noted that, compared to CVD, which is typically performed at temperatures of 400–900°C, ALD can be performed at temperatures of 100–400°C. That is, ALD is superior in suppressing thermal damage to metal foils.

[0119] Examples of oxidants used in the ALD process include water, oxygen, and ozone. The oxidant can be supplied to the reaction chamber in the form of plasma, with the oxidant serving as a raw material.

[0120] Precursors containing a first metal and a second metal can be, for example, organometallic compounds containing both a first metal and a second metal. Precursors containing a first metal can be, for example, organometallic compounds containing a first metal. Precursors containing a second metal can be, for example, organometallic compounds containing a second metal. Thus, the first metal and the second metal readily chemisorb onto the target material. Various organometallic compounds conventionally used in the ALD process can be used as precursors.

[0121] Examples of Al-containing precursors include trimethylaluminum ((CH3)3Al).

[0122] Examples of precursors containing Si include N-sec-butyl(trimethylsilyl)amine (C7H). 19 NSi), 1,3-diethyl-1,1,3,3-tetramethyldisilazane (C8H) 23 NSi2), tetramethylsilane (Si(CH3)4), tetraethoxysilane (Si(OC2H5)4), silicon tetrachloride (SiCl4), etc.

[0123] Examples of Ti-containing precursors include bis(tert-butylcyclopentadienyl)titanium dichloride (IV)(C 18 H 26 C 12Ti, tetra(dimethylamino)titanium(IV) ([(CH3)2N]4Ti), titanium tetrachloride (TiCl4), titanium ethoxide (IV) (Ti[O(C2H5)]4), etc.

[0124] Examples of precursors containing Ta include (tert-butylimide)tris(methylethylamino)tantalum(V)(C) 13 H 33 N4Ta), tantalum pentaethanol (V) (Ta(OC2H5)5), etc.

[0125] Examples of Zr-containing precursors include bis(methyl-n-5-cyclopentadienyl)methylmethoxyzirconium (Zr(CH3C5H4)2CH3OCH3), tetra(dimethylamido)zirconium (IV) ([(CH3)2N]4Zr), and tert-butoxidezir (IV) (Zr[OC(CH3)3]4).

[0126] Examples of precursors containing Hf include hafnium tetrachloride (HfCl4), tetra(dimethylamino)hafnium (Hf[N(CH3)2]4), and tert-butanol hafnium (Hf[OC(CH3)3]4).

[0127] Examples of Zn-containing precursors include zinc chloride, dimethyl zinc, and diethyl zinc.

[0128] Examples of precursors containing Nb include niobium ethanol (V)(Nb(OCH2CH3)5 and tris(diethylamido)(tert-butylimide)niobium (V)(C 16 H 39 N4Nb), etc.

[0129] When forming a dissimilar metal composite layer as a conductive layer, a precursor containing carbon (C) can be used together with a precursor containing a first metal and a second metal. Examples of precursors containing C include alkanes with 5 to 11 carbon atoms, such as hexane.

[0130] A raw material gas containing a first metal and a second metal can be alternately supplied to the reaction chamber with a raw material gas containing C to form a conductive layer in which the first metal, the second metal, and C coexist.

[0131] Alternatively, a raw material gas containing a first metal and a second metal can be supplied to the reaction chamber to form a first conductive layer in which the first metal and the second metal coexist. Next, a raw material gas containing C can be supplied to the reaction chamber to form a second conductive layer containing C.

[0132] (Step 3)

[0133] The method for manufacturing the electrode foil also includes a third step of chemically converting (anodic oxidation) the electrode foil whose surface is covered by a dissimilar metal composite layer (first layer) on the substrate. This allows the formation of a second layer containing an oxide of a valve-acting metal from the substrate between the substrate and the first layer. The thickness T2 of the second layer can be controlled by the voltage applied to the electrode foil during the chemical conversion.

[0134] In the ALD process, the feed gas can easily reach the deepest part of the etched pit, enabling the stable formation of the first layer in the B1-B3 region of the porous material. Therefore, even when forming a second layer, a first layer larger than the second layer can be formed in the B1-B3 region.

[0135] Electrolytic capacitors

[0136] The electrolytic capacitor of this embodiment includes the electrode foil for an electrolytic capacitor described above. The electrolytic capacitor, for example, includes an anode foil having a dielectric layer on its surface and a cathode portion covering at least a portion of the dielectric layer. The cathode portion includes, for example, a cathode foil and an electrolyte. The surface of the substrate of at least one of the anode foil and the cathode foil is covered by a dissimilar metal composite layer. In the case of the anode foil, the dissimilar metal composite layer is configured as an oxide layer (dielectric layer). In the case of the cathode foil, the dissimilar metal composite layer is configured as a conductive layer.

[0137] The following is a detailed description of the components of an electrolytic capacitor other than the electrode foil.

[0138] (electrolytes)

[0139] Electrolytes can contain liquid components and / or solid electrolytes. When the electrolyte does not contain a solid electrolyte, the liquid component is the electrolyte solution (liquid electrolyte). When the electrolyte contains a solid electrolyte, the liquid component may or may not be an electrolyte solution. The liquid component can enhance the repairability of the dielectric layer on the anode side of an electrolytic capacitor. As a solid electrolyte, a conductive polymer can be used.

[0140] (Conductive polymer)

[0141] Examples of conductive polymers include polypyrrole, polythiophene, and polyaniline. A single conductive polymer can be used, or two or more can be used in combination. The weight-average molecular weight of conductive polymers is, for example, 1000 to 100000.

[0142] It should be noted that in this specification, polypyrrole, polythiophene, and polyaniline refer to polymers with polypyrrole, polythiophene, and polyaniline as their basic backbones, respectively. Therefore, polypyrrole, polythiophene, and polyaniline may also include their respective derivatives. For example, polythiophene includes poly(3,4-ethylenedioxythiophene) (PEDOT), etc.

[0143] Conductive polymers can be doped with dopants. A single dopant can be used, or two or more can be used in combination. From the viewpoint of suppressing dedoping of self-conductive polymers, polymeric dopants are preferred. Examples of polymeric dopants include anions of polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallyl sulfonic acid, polypropylene sulfonic acid, and polymethyl methacrylate sulfonic acid. Among these, polystyrene sulfonic acid (PSS) is preferred. The weight-average molecular weight of the polymeric dopant is, for example, 1000 to 100000.

[0144] (Liquid component)

[0145] As a liquid component, it can be a non-aqueous solvent or a mixture of a non-aqueous solvent and an ionic substance (solute, such as an organic salt) dissolved therein (i.e., an electrolyte). The non-aqueous solvent can be an organic solvent or an ionic liquid. A high-boiling-point solvent is preferred as the non-aqueous solvent. Examples of non-aqueous solvents include polyol compounds such as ethylene glycol, cyclic sulfone compounds such as sulfolane, lactone compounds such as γ-butyrolactone, amide compounds such as N-methylacetamide, ester compounds such as methyl acetate, carbonate compounds such as propylene carbonate, ether compounds such as 1,4-dioxane, and ketone compounds such as methyl ethyl ketone. Alternatively, a polymeric solvent can be used as a high-boiling-point solvent. Examples of polymeric solvents include polyalkylene glycols such as polyethylene glycol.

[0146] Liquid components can contain both acidic and alkaline components. Organic carboxylic acids can be used as acidic components. These can be aliphatic or aromatic carboxylic acids. Examples of organic carboxylic acids include maleic acid, phthalic acid, benzoic acid, pyromellitic acid, and resorcinol.

[0147] Acid components can include inorganic acids. Examples of inorganic acids include phosphoric acid, phosphorous acid, hypophosphite, alkyl phosphates, boric acid, fluoroboric acid, tetrafluoroboric acid, hexafluorophosphate, benzenesulfonic acid, and naphthalenesulfonic acid.

[0148] Examples of alkali components include primary amines such as monoalkylamines, secondary amines such as dialkylamines, and tertiary amines such as trialkylamines. Additionally, compounds with alkyl-substituted amidine groups (imidazolium compounds, benzimidazole compounds, alicyclic amidine compounds, etc.) can be used as alkali components. Compounds with alkyl-substituted amidine groups can be quaternaries.

[0149] The liquid component can contain salts containing both acidic and alkaline components. These salts can be inorganic or organic. Examples of organic salts include trimethylamine maleate, triethylamine borosalicylate, ethyldimethylamine phthalate, mono-1,2,3,4-tetramethylimidazoline phthalate, and mono-1,3-dimethyl-2-ethylimidazoline phthalate.

[0150] The pH of the liquid component can be less than 7 or below 5. By maintaining the pH of the liquid component within this range, dedoping of the conductive polymer can be suppressed.

[0151] (spacer)

[0152] In electrolytic capacitors that use an electrolyte as the electrolyte, a spacer can be used to separate the anode foil from the cathode foil. The spacer can be made of materials such as nonwoven fabrics or films primarily composed of cellulose, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, vinylon, nylon, aromatic polyamides, polyimides, polyamide-imides, polyether-imides, rayon, or vitreous materials.

[0153] Here, Figure 5 This is a cross-sectional schematic diagram of the electrolytic capacitor according to this embodiment. Figure 6 This is a schematic diagram showing the unfolding of a portion of the winding contained in the electrolytic capacitor. However, the following embodiments do not limit the invention.

[0154] like Figure 5 As shown, the electrolytic capacitor 200 includes a capacitor element and a bottomed housing 211 housing the capacitor element. The capacitor element includes a wound body 100 and a conductive polymer (not shown) attached to the wound body 100. Additionally, the electrolytic capacitor 200 includes a sealing member 212 that closes the opening of the bottomed housing 211, a base plate 213 covering the sealing member 212, and leads 60A and 60B extending from the sealing member 212 and through the base plate 213. The capacitor element and a liquid component (not shown) are housed together in the bottomed housing 211. The bottomed housing 211 is drawn inwards near the opening end, and the opening end is rolled up by riveting it to the sealing member 212.

[0155] The wound body 100 includes an anode foil 10, a cathode foil 20, and a spacer 30 between them. A conductive polymer is attached in such a way that it covers at least a portion of the surface of the dielectric layer of the anode foil 10. The wound body 100 also includes a lead connector 50A connected to the anode foil 10 and a lead connector 50B connected to the cathode foil 20. Lead connectors 50A and 50B are connected to leads 60A and 60B, respectively.

[0156] The anode foil 10 and cathode foil 20 are wound together with a spacer 30 between them. The outermost periphery of the wound is secured by a stop-winding tape 40. It should be noted that... Figure 6 This indicates the state of a portion of the coil being unfolded before the outermost circumference is fixed.

[0157] In the above embodiments, a wound electrolytic capacitor has been described, but the application scope of the present invention is not limited to the above content, and it can also be applied to other electrolytic capacitors, such as stacked electrolytic capacitors.

[0158] Industrial availability

[0159] The electrode foil for electrolytic capacitors of the present invention is suitable for use in electrolytic capacitors requiring high performance and high reliability.

[0160] Explanation of reference numerals in the attached figures

[0161] 10: Anode foil, 20: Cathode foil, 30: Spacer, 40: Anti-winding tape, 50A, 50B: Lead connectors, 60A, 60B: Leads, 100: Winding body, 110: Substrate, 111: Core, 112: Porous part, 120: Dissimilar metal composite layer, 121: First layer, 122: Second layer, 200: Electrolytic capacitor, 211: Bottom shell, 212: Sealing component, 213: Base plate.

Claims

1. An electrode foil for an electrolytic capacitor, comprising: Substrate, comprising valve-acting metal; and A dissimilar metal composite layer that covers the surface of the substrate. The dissimilar metal composite layer includes a mixed region containing a first metal and a second metal different from the first metal. The mixed storage region constitutes at least 50% of the thickness direction of the dissimilar metal composite layer. The content of the first metal relative to all metals, M1, and the content of the second metal relative to all metals, M2, in the mixed storage region are both 1 atom% or more. The dissimilar metal composite layer is an oxide layer. The mixed storage area contains impurities. The impurity is selected from at least one of hydrogen, carbon, and nitrogen. The impurity content in the mixed storage region is less than 25 atomic percent relative to the total of all metals and impurities in the mixed storage region.

2. The electrode foil for an electrolytic capacitor according to claim 1, wherein, The content of the first metal relative to all metals, M1, and the content of the second metal relative to all metals, M2, in the mixed storage area are respectively above 1 atomic% and below 99 atomic%.

3. The electrode foil for an electrolytic capacitor according to claim 1, wherein, When the mixed storage region is divided into three equal parts, A1, A2, and A3, in the thickness direction of the dissimilar metal composite layer starting from the surface side of the layer,... The atomic ratio R of the first metal to the second metal in region A1 A1 The atomic ratio R of the first metal to the second metal in region A2 A2 The atomic ratio R of the first metal to the second metal in region A3 A3 Satisfying 0.8≤R A2 / R A1 ≤1.2 and 0.8≤R A3 / R A2 The relationship is ≤1.

2.

4. The electrode foil for an electrolytic capacitor according to claim 3, wherein, The atomic percentage (M1) of the first metal in region A1 relative to all metals. A1 The atomic percentage (M1) of the first metal in region A2 relative to all metals. A2 and the atomic percentage (M1) of the first metal in region A3 relative to all metals. A3 Satisfying 0.9≤M1 A2 / M1 A1 ≤1.1, 0.9≤M1 A3 / M1 A2 ≤1.1, 1≤M1 A1 1≤M1 A2 And 1≤M1 A3 The relationship.

5. The electrode foil for an electrolytic capacitor according to claim 3, wherein, The atomic percentage (M2) of the second metal in region A1 relative to all metals. A1 The atomic percentage (M2) of the second metal in region A2 relative to all metals. A2 and the atomic percentage (M2) of the second metal in region A3 relative to all metals. A3 Satisfying 0.9≤M2 A2 / M2 A1 ≤1.1 and 0.9≤M2 A3 / M2 A2 ≤1.1, 1≤M2 A1 1≤M2 A2 And 1≤M2 A3 The relationship.

6. The electrode foil for an electrolytic capacitor according to claim 1, wherein, The substrate has a porous portion and a core portion continuous with the porous portion. The dissimilar metal composite layer covers the surface of the porous portion. When the porous material is divided into three equal regions, B1, B2, and B3, in the thickness direction of the porous material from the side opposite to the core, The atomic ratio R of the first metal to the second metal in region B1 B1 The atomic ratio R of the first metal to the second metal in region B2. B2 The atomic ratio R of the first metal to the second metal in region B3. B3 Satisfy R B3 <R B2 <R B1 The relationship.

7. The electrode foil for an electrolytic capacitor according to claim 6, wherein, The atomic percentage (M1) of the first metal in region B1 relative to all metals. B1 The atomic percentage (M1) of the first metal in region B2 relative to all metals. B2 and the atomic percentage (M1) of the first metal in region B3 relative to all metals. B3 Satisfy M1 B3 <M1 B2 <M1 B1 The relationship.

8. The electrode foil for an electrolytic capacitor according to claim 6, wherein, The atomic percentage (M2) of the second metal in region B1 relative to all metals. B1 The atomic percentage (M2) of the second metal in region B2 relative to all metals. B2 and the atomic percentage (M2) of the second metal in region B3 relative to all metals. B3 Meets M2 B1 <M2 B2 <M2 B3 The relationship.

9. The electrode foil for an electrolytic capacitor according to any one of claims 1 to 8, wherein, The first metal comprises at least one selected from titanium, tantalum, hafnium, zirconium, and zinc. The second metal comprises at least one selected from silicon and aluminum.

10. The electrode foil for an electrolytic capacitor according to any one of claims 1 to 8, wherein, The first metal is titanium, and the second metal is silicon. The silicon content in the mixed storage region is between 1 atomic% and 70 atomic% relative to all metals.

11. The electrode foil for an electrolytic capacitor according to any one of claims 1 to 8, wherein, The first metal is titanium, and the second metal is aluminum. The aluminum content in the mixed storage area is more than 1 atomic% and less than 55 atomic% relative to all metals.

12. The electrode foil for an electrolytic capacitor according to any one of claims 1 to 8, wherein, The hydrogen content in the mixed storage region is less than 10 atomic percent relative to the total of all metals and impurities in the mixed storage region.

13. The electrode foil for an electrolytic capacitor according to any one of claims 1 to 8, wherein, A layer comprising an oxide of the valve-acting metal is provided between the substrate and the dissimilar metal composite layer.

14. An electrolytic capacitor comprising electrode foil for an electrolytic capacitor as described in any one of claims 1 to 13.

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