JP2014072267A - Aluminum collector foil having through hole and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such problems of an aluminum electrolytic capacitor that when providing many through holes of about 1 μm by etching an aluminum foil for the electrode thereof, a high purity foil having a high occupancy of cubic azimuth is required, but a high purity foil is soft and workability is poor because the foil strength decreases, and that foil thickness of 50 μm or more is required for increasing the occupancy of cubic azimuth, and to obtain an aluminum collector foil having through holes capable of providing many through holes of about 1 μm, while maintaining a required foil strength even if the foil is made thin.SOLUTION: An aluminum collector foil has a plurality of dent parts, and through holes of smaller diameter than that of the dent part at the dent parts.

Description

  The present invention relates to an aluminum current collector foil having a through hole and a method for producing the same. In particular, the present invention relates to an aluminum current collector foil having a through hole used for a lithium ion capacitor or the like using lithium ions and a method for manufacturing the same.

  The lithium ion capacitor using a lithium ion uses a pre-doping technique in which lithium is previously occluded in the negative electrode material, whereby the voltage can be increased and the energy density can be improved. And in order to perform this pre dope efficiently, the method of providing many through-holes in the electrical power collector of an electrode is performed.

By the way, in order to improve the energy density, the electrode capacity increases when the thickness of the current collector is reduced. However, the foil strength of the current collector decreases as the current collector becomes thinner, and a through hole is provided in the current collector. And the foil strength is more likely to decrease.
Patent Document 1 describes that, as a lithium ion capacitor, a preferable current collector has a thickness of 50 μm or less, and a diameter of an inscribed circle of a preferable through hole is 0.2 μm to 5 μm.

JP 2011-74468 A

  By the way, in an aluminum electrolytic capacitor, an aluminum foil for the electrode may be etched to provide a large number of through holes of about 1 μm. In this case, the foil needs to have a high purity and a high occupation ratio in the cube orientation. If the purity is high, the foil is soft and the strength of the foil is lowered, and the processability is poor. Moreover, in order to increase the occupancy ratio of the cube orientation, the foil thickness becomes thicker than 50 μm, and cannot be directly used as a current collector foil used for a lithium ion capacitor or the like.

  The present invention has been made to solve the above-described problems, and can maintain the required foil strength even when the thickness of the foil is reduced, and can have aluminum having through holes that can provide a large number of through holes of about 1 μm. The purpose is to obtain current collector foil.

In order to solve the above problems, the present invention provides an aluminum current collector foil having the following through-holes.
(1) An aluminum current collector foil having a plurality of dent portions and through holes having a diameter smaller than that of the dent portions in the dent portions.
(2) The aluminum current collector foil according to (1), wherein the inscribed circle has a diameter of 5 μm to 15 μm, the diameter of the through hole is 0.5 μm to 3 μm, and the outer thickness is 20 μm to 50 μm.
(3) The aluminum current collector foil according to (1) or (2), to which 1 ppm to 100 ppm of manganese, iron, magnesium, silicon, copper, or lead is added.
(4) A method for producing an aluminum current collector foil comprising a step of providing a plurality of dent portions on an aluminum foil with an embossing roll, and a step of obtaining through holes in the dent portions by etching of pitting corrosion.
(5) A step of forming a protective film such as an oxide film or a hydroxide film in advance on an aluminum foil, providing a plurality of dent portions with an embossing roll, and simultaneously obtaining a through hole in the dent portion by destroying the protective film. A method for producing an aluminum current collector foil comprising:

  According to the configuration of the present invention, the required foil strength can be maintained even when the foil is thinned, and an aluminum current collector foil can be obtained in which a large number of through holes of about 1 μm can be provided.

The perspective view of the partial cross section of the aluminum collector foil which has a through-hole of this invention is shown. The manufacturing method of the aluminum current collection foil which has the through-hole of this invention is shown. The manufacturing method of the aluminum current collection foil which has another through-hole of this invention is shown.

The dent portion described in the present invention is a concave portion provided on the surface of the current collector aluminum foil, and is provided on one or both sides of the foil. When providing on both sides, it is preferable to arrange the locations on both sides as much as possible. The shape of the indented part is about 5 μm to 15 μm as the diameter of the inscribed circle on the surface part of the foil, and if it is smaller than 5 μm, the processing on the indenting tool side becomes difficult, and wear and breakage during use tend to occur. On the other hand, when the thickness is larger than 15 μm, the number of the recessed portions is reduced, and accordingly, the number of through holes is reduced, and the efficiency of pre-doping is easily deteriorated.
The method of creating a dent portion can provide a dent portion on one side by a combination of an embossing roll and a flat roll, and on both sides by a combination of embossing rolls. When providing a dent part on both surfaces, it adjusts so that a dent part may overlap with the gear etc. which combined with the embossing roll.
The vertical cross-sectional shape of the indented portion is not particularly limited, such as a rectangle, a trapezoid, or a semicircular shape. However, in the case of a single-sided shape, it may be a pointed triangle. In the case of double-sided, it is easier to align the position if the tip is not sharp.

  The through hole described in the present invention is a hole penetrating from the front surface to the back surface of the current collector aluminum foil, and can be easily formed by an etching method used for an aluminum electrolytic capacitor. The aluminum foil can easily penetrate through a dent portion where the distance from the front surface to the back surface is short.

  The aluminum foil described in the present invention has a thickness of about 20 μm to 50 μm, and aluminum added with manganese, iron, magnesium, silicon, copper, lead, or the like can be used. These additives can improve the strength or etchability of the aluminum. For the etching property, the amount of iron, copper, lead or the like is adjusted so that pitting corrosion is more likely to occur than the overall corrosion. Their addition amount is preferably about 1 ppm to 100 ppm.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1: has shown the perspective view of the partial cross section of the aluminum current collection foil which has a through-hole of this invention.
The aluminum current collector foil has a plurality of recessed portions 1, an etching hole 2 formed on the entire surface by etching, and a through hole 3 in which a part of the etching hole 2 penetrates from the front surface to the back surface of the aluminum current collector foil. doing. The through hole 3 is smaller than the diameter of the dent portion 1, and the dent portion 1 is a portion where the thickness of the aluminum current collector foil is reduced. Therefore, the through hole 3 is easily formed by the dent portion 1. Further, since the portion other than the dent portion 1 of the aluminum current collector foil is a portion having a thicker foil thickness than the dent portion 1, the through hole 3 is difficult to be formed, and there is a portion without the etching hole 2. Contributes to foil strength.
Moreover, although the dent part 1 is provided in at least one of the front surface or the back surface of the aluminum current collector foil, it is preferable that the aluminum current collector foil has a thin portion because the aluminum current collector foil has the same position as much as possible.
In addition, an electrode material is provided on the surface of the aluminum current collector foil. The electrode material is applied to the surface of the aluminum current collector foil and then pressed. Here, the etching holes 2 provided on the entire surface of the aluminum current collector foil can firmly laminate the electrode material provided on the surface by the anchor effect. On the other hand, in the indented portion 1, the electrode material and the aluminum current collector foil are pressed and pressed more loosely than the other portions, so that the through hole 3 is less likely to be clogged with the electrode material and prevents predoping from being hindered. be able to.

FIG. 2 shows a method for producing an aluminum current collector foil having a through hole according to the present invention. 2A shows the state before etching, and FIG. 2B shows the state after etching.
First, aluminum is formed into a foil shape to a specified thickness by cold rolling. Next, as shown in FIG. 2A, the dent portion 1 is provided in the aluminum foil 5 by the embossing roll 4. The convex portion 6 of the embossing roll has a triangular, semicircular, trapezoidal, rectangular, etc. cross section in the convex direction. The narrower tip of the convex portion 6 tends to dent the aluminum foil 5 at a low pressure. Further, it is preferable that the tip of the convex portion 6 is not narrowed when the dent portion 1 is provided from both surfaces, since the approach distance range between the dents is widened and the allowable displacement range is widened.
Next, the processing oil adhering to the surface during cold rolling or embossing is removed. However, if the foil is softened when heated to decompose the rolling oil, it is degreased with an alkali.
Next, as shown in FIG. 2B, the aluminum foil 5 is etched. Etching technology can be applied to aluminum electrolytic capacitors. For example, a direct current is passed through an aluminum foil to form an etching hole by electrochemical etching, and then an alternating current is passed in a solution containing hydrochloric acid or sulfuric acid. Etching can reduce the melting of the surface of the aluminum foil, prevent the mechanical strength from being lowered, and efficiently increase the diameter of the etching hole.
Then, an etching hole 2 formed on the entire surface and a through hole 3 in which a part of the etching hole 2 penetrates from the front surface to the back surface of the aluminum current collector foil are formed by etching. The through hole 3 is smaller than the diameter of the dent portion 1, and the dent portion 1 is a portion where the thickness of the aluminum current collector foil is reduced. Therefore, the through hole 3 is easily formed by the dent portion 1.

FIG. 3 shows a method for producing an aluminum current collector foil having another through hole according to the present invention.
3A shows the state after the surface treatment, FIG. 3B shows the state after the embossing, and FIG. 3C shows the state after the etching.
The protective film layer 7 formed by the surface treatment is an etching suppression layer provided on both surfaces of the aluminum foil 5 and has a thickness that is easily deformed or damaged by the pressing of the convex portion 6 of the embossing roll 4. Therefore, the thickness is preferably 0.01 μm to 0.5 μm. A particularly preferred thickness is 0.02 μm to 0.1 μm. When the thickness is less than 0.01 μm, the surface treatment is meaningless because of the same thickness as the natural oxide film. On the other hand, when it is thicker than 0.5 μm, it is difficult to damage the protective film layer 7 so that the convex portion 6 of the embossing roll 4 can be etched.
As the surface treatment, for example, an oxide film layer by heating or anodic oxidation or a hydroxide layer by hydration treatment with hot water is provided.
The heat treatment is performed at about 200 ° C. to 550 ° C. in the atmosphere. In addition, as anodization, a commonly used solution such as a boric acid bath, an oxalic acid bath, a phosphoric acid bath, an adipic acid bath, or the like is used, and the thickness of the oxide film is controlled by changing the voltage. Moreover, as a hydration process, you may process only with a pure water and you may use a boric acid, a borax, adipic acid, potassium hydrogenphosphate, etc. as a trace amount additive.
Next, as shown in FIG. 3B, the dent portion 1 is provided in the aluminum foil 5 by the embossing roll 4. At this time, the protective film layer 7 is partially deformed or damaged in accordance with the dent.
Next, as shown in FIG. 3C, the aluminum foil 5 is etched. In this case, since the protective film layer 7 is present, the portions other than the dent portion 1 are difficult to be etched, and the portion without the etching hole 2 is wider than when the protective film layer 7 is not provided. It can contribute by foil strength.

  DESCRIPTION OF SYMBOLS 1 ... Dented part, 2 ... Etching hole, 3 ... Through-hole, 4 ... Embossing roll, 5 ... Aluminum foil, 6 ... Convex part, 7 ... Protective film layer

Claims (5)

  An aluminum current collector foil having a plurality of dent portions and through holes having a diameter smaller than that of the dent portions in the dent portions.   2. The aluminum current collector foil according to claim 1, wherein the inscribed circle has a diameter of 5 μm to 15 μm, the diameter of the through hole is 0.5 μm to 3 μm, and the outer thickness is 20 μm to 50 μm.   The aluminum current collector foil according to claim 1 or 2, wherein manganese, iron, magnesium, silicon, copper, or lead is added in an amount of 1 ppm to 100 ppm.   A method for producing an aluminum current collector foil, comprising: a step of providing a plurality of dent portions on an aluminum foil by an embossing roll; and a step of obtaining through holes in the dent portions by etching of pitting corrosion.   Aluminum having a step of forming a protective film such as an oxide film or a hydroxide film in advance on an aluminum foil, providing a plurality of dent portions by an embossing roll, and simultaneously obtaining a through hole in the dent portion by destroying the protective film The manufacturing method of current collection foil.

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