JP6959054B2 - Perforated metal foil - Google Patents

Description

The present invention is a perforated metal foil provided with a plurality of perforations, particularly an electrode for a power storage device having high energy density and high output characteristics, which can be manufactured based on a simple and practical predoping technique. And the power storage device including the electrode thereof.

At present, high output and high energy density of power storage devices are required, and along with this, power storage devices such as lithium ion capacitors (LIC) are being developed.
As a solution to the high output and high energy density, the pre-doping technology in which lithium (Li) ions are supported on the negative electrode is attracting attention.
Among them, by using a metal foil having a through hole as a current collector for an electrode and a current collector core, a simple and practical power storage device based on a pre-doping technique can be manufactured.
At this time, the opening ratio, which is the ratio of the opening area to the unit area, is preferably set large in order to increase the pre-doping rate or the uniformity of the pre-doping, but the electrode layer on the current collector From the viewpoint of ease of formation and electrode strength, it is not preferable to make it too large.

Positive and negative electrode current collecting metal foils of LIC and next-generation lithium ion batteries (LIB) are generally produced by applying an active material to a metal foil having a plurality of openings, and are described in, for example, Patent Documents 1 and 2 below. Has a portion (opening region) in which a large number of holes are formed in the central portion of the metal foil in the width direction as shown in FIG. 2, and holes are provided at the edge portion in the longitudinal direction of the metal foil. A perforated metal foil in which an unperforated portion (non-perforated region) is present is disclosed.

By the way, in the case of a metal foil having through holes as shown in FIG. 2, the presence of a non-perforated region at the end of the foil prevents the foil from breaking when a force is applied in the longitudinal direction, and the inside of the machine is prevented. Foil can be passed through, but when a force is applied in the longitudinal direction, unevenness due to twisting may occur at the boundary (position of the boundary line) between the perforated region and the non-perforated region.
This is because the tensile strength decreases in the open region and a difference from the tensile strength in the non-open region occurs, causing twisting. The larger the open ratio in the open region, the larger the difference. Become. Then, the unevenness due to the twist adversely affects the running performance of the foil in the coating machine in the coating process of the active material, which is the next step, and impairs the coating property.

Japanese Unexamined Patent Publication No. 2003-168441 Japanese Unexamined Patent Publication No. 2013-065517

In view of the above problems, the present invention reduces the uneven distribution of tensile strength between the end non-perforated region and the perforated region (high perforation rate region) in a tension environment in the perforated metal foil for a power storage device. It is an object of the present invention to provide a perforated metal foil capable of suppressing a height difference of unevenness.

As a result of studies to achieve the above object, the present inventors have made at least one or more between the non-perforated region at the end and the high perforated region which is the central region in the metal perforated foil. By setting a low perforation rate region (a region where the perforation rate is lower than the perforation region in the central region), the tension between the end non-perforation region and the high perforation ratio region under a tensile environment. The present invention has been completed by finding that it is possible to reduce the uneven distribution of strength and suppress the height difference of unevenness.

In the perforated metal foil of the present invention capable of solving the above problems, at least one first perforation region (high opening) in which through holes having a pore diameter of 0.36 mm or more and 1.2 mm or less are formed with a perforation rate of 10% or more. The pore ratio region), at least one second pore region (low pore ratio region) in which the through hole is formed at a pore ratio lower than the pore ratio of the first pore region, and a through hole. At least one non-perforated region is arranged in the width direction of the metal foil, and the first perforated region, the second perforated region, and the non-perforated region are all the lengths of the metal foil. It extends parallel to the direction, the second perforated region is arranged adjacent to the first perforated region, and the non-perforated region is arranged adjacent to the second perforated region. It is characterized by that.
In the specification of the present application, the "opening ratio" is the ratio of the total opening area of a plurality of through holes existing in the unit area to the unit area extending along the longitudinal direction of the metal foil, that is, It means the ratio of the opening area per unit area (opening area ratio), but since the opening area is determined by the hole diameter of the through hole and the number of holes in the unit area, the low opening rate in the present invention is the hole diameter. It may be achieved by reducing the number of holes, reducing the number of holes, or it may be a composite.

Further, according to the present invention, in the perforated metal foil having the above-mentioned characteristics, the second perforation region is formed at a perforation rate of 30 to 70% as compared with the first perforation region. It is a feature.

Further, the present invention is characterized in that, in the perforated metal foil having the above-mentioned characteristics, the width of the second perforated region is 2 mm or more and 50 mm or less.

Further, in the present invention, in the perforated metal foil having the above-mentioned characteristics, the non-perforated region is provided at at least one end in the width direction of the metal foil, and the width of the non-perforated region is widened. It is also characterized in that it is 2 mm or more and 50 mm or less.

Further, the present invention is characterized in that, in the perforated metal foil having the above-mentioned characteristics, the thickness of the metal foil is 3 μm to 50 μm.

Further, the present invention is also characterized in that, in a perforated metal foil having the above characteristics, the surface roughness of the metal foil (based on Ra, JIS B 0601: 2001) is 0.5 μm or less. be.

Since the decrease in tensile strength in the open region correlates with the open ratio, uneven distribution of force occurs at the boundary between the high open ratio region and the non-open region due to the difference in tensile strength, which causes unevenness due to twisting. However, in the perforated metal foil of the present invention, a low perforation rate region is arranged between the high perforation rate region and the non-perforation region, whereby the non-perforation region and the low perforation region are arranged. The boundary between the rate region, the low pore ratio region, the high pore ratio region, and the region with different pore ratios increases, and the difference in the pore ratio at the boundary becomes small, so the uneven distribution force becomes small, and the height difference of the unevenness becomes small. Can be made smaller.

It is a simple schematic diagram (plan view) which shows the perforated metal foil which concerns on embodiment of this invention. It is a schematic diagram which shows the conventional perforated metal foil (the perforated metal foil which has the non-perforated area at the end).

The perforated metal foil according to the present invention is a metal foil in which a perforated portion is provided by processing a metal foil. Hereinafter, embodiments of the present invention will be described with reference to FIG. It is not limited to those illustrated in.
FIG. 1 is a plan view schematically showing a state in which a second perforation region (low perforation rate region) 2 exists between a first perforation region (high perforation rate region) 1 and a non-perforation region 3. Is. At this time, the hole diameter and the arrangement of the holes in the opened portion are large and simplified so as to be easy to explain. The openings provided in the first opening region and the second opening region are generally circular, but are not limited thereto.
In the width direction of the perforated metal foil of the present invention, at least one first perforation region (high perforation rate) in which through holes having a hole diameter of 0.36 mm or more and 1.2 mm or less are formed with a perforation rate of 10% or more. Region 1), at least one second opening region (low opening ratio region) 2 in which a through hole is formed at a pore ratio lower than that of the first opening region 2, and a through hole At least one non-perforated region 3 which is not provided is arranged, and these first perforated region 1, second perforated region 2 and non-perforated region 3 are all parallel to the longitudinal direction of the metal foil. It extends in the direction.

Then, in the perforated metal foil of the present invention, as shown in FIG. 1, the second perforated region 2 is located adjacent to the first perforated region 1, and the non-perforated region 3 is It is arranged so as to be adjacent to the second opening region 2 without being adjacent to the first opening region 1. In the present invention, it is preferable that the non-perforated regions 3 are arranged at both end edges of the perforated metal foil, but both end edges may be the second perforated regions 2.

In the present invention, the opening provided in the first opening region 1 may have an opening rate of 10% or more, preferably 30% or more and 60% or less, and particularly preferably 40% or more and 50% or less. In the present invention, in order to reduce the height difference of the unevenness at the boundary between the region where the through hole is formed and the non-perforated region, the opening ratio in the second open region 2 is set to open the first open region 1. The pore ratio is preferably 30 to 70%.
The processing method for providing holes in the first hole region 1 and the second hole region 2 is not particularly limited, and general punching press, roll punching press, etching, laser processing, etc. are performed. Both can be used.

The width (length in the width direction of the metal foil) of the second perforated region 2 and the non-perforated region 3 in the present invention is preferably 2 mm to 50 mm, and is formed at at least one end of the metal foil in the width direction. Is preferable.
In the present invention, the structure may be such that the second perforated region 2 is arranged at the end of the perforated metal foil, but the second perforated region 2 includes the first perforated region 1 and the non-perforated region 3. It is preferable to be arranged between.

The thickness of the perforated metal foil of the present invention is not particularly limited, but the thickness of the perforated metal foil used as the positive and negative electrode current collecting metal foils of LIC and LIB is preferably 3 μm to 50 μm, and the metal foil is said to be. The average surface roughness (based on Ra, JIS B 0601: 2001) is not particularly limited, but is preferably 0.5 μm or less.
Further, the material of the perforated metal foil of the present invention is generally aluminum foil, copper foil or nickel foil, but is not limited thereto.

In the case of the perforated metal foil of the present invention in which the first perforated region 1, the second perforated region 2 and the non-perforated region 3 are arranged in the width direction of the metal foil as shown in FIG. By arranging the second opening region 2 adjacent to the one opening region 1 and arranging the non-opening region 3 adjacent to the second opening region 2, at the boundary of the adjacent regions. Uneven distribution of force due to the difference in tensile strength is unlikely to occur, unevenness due to twisting is unlikely to occur, the uneven distribution force is small, and the height difference of unevenness can be reduced.
Next, the present invention will be described in more detail based on Examples, but the present invention is not limited to Examples.

Manufacture of perforated metal foil As a metal foil, a copper foil having a thickness of 15 μm and a surface roughness (Ra) of 0.2 μm was prepared, and the copper foil was punched. A perforated metal foil having each perforation rate and perforation region was prepared. Then, the perforated metal foils were cut into a size of 310 × 1000 mm, respectively. A non-perforated region having a width of 5 mm is arranged at both ends of the perforated metal foil in the width direction, and a first perforated region is arranged at the center of the metal foil in the width direction. The width of the second opening region in each of No. 3 was set to 5 mm.
For each perforated metal foil having a thickness of 15 μm produced above, one side of the metal foil is fixed, a load of 3 kgf is applied to the other side to apply tension, and the height difference of the unevenness generated at the region boundary position is detected. The measurement was performed using (Omron's smart sensor linear proximity type ZX-E series φ8 mm). The results are shown in Table 1 below.

From the results of Table 1 above, Example 1 in which the second opening region exists as compared with the height difference of the unevenness of the metal foils of Comparative Examples 1 to 3 in which the second opening region which is the low opening ratio region does not exist. The height difference of the unevenness of the metal foil of ~ 3 is small, and by providing the second opening region, the height difference of the unevenness generated between the regions is reduced, and the inside of the coating machine is used in the coating process of the active material. It was confirmed that the running performance of the foil was good and the uniformity of coating was improved.

In the perforated metal foil of the present invention, since the first perforated region and the non-perforated region are not arranged adjacent to each other, they are arranged at the boundary position between the regions having different perforated states arranged in the width direction of the metal foil. Since waviness and the like do not occur and the uneven height difference of the metal foil can be alleviated, it is particularly useful for producing positive and negative electrode current collecting metal foils of LIC and LIB.

1 First opening area (high opening rate area)
2 Second opening area (low opening rate area)
3 Non-perforated area

Claims (6)

A metal foil provided with a plurality of holes (excluding those having a burr height of 0.1 mm or more around the holes), and the metal foil has a hole diameter of 0.36 mm or more and 1.2 mm or less. The through hole is formed at least one first opening region in which the through hole is formed at a hole opening rate of 10% or more, and the through hole is formed at a hole opening rate lower than the opening rate of the first opening area. At least one second perforated region and at least one non-perforated region not provided with a through hole are arranged in the width direction of the metal foil, and the first perforated region, the second perforated region and the second perforated region are arranged. Each of the non-perforated regions extends parallel to the longitudinal direction of the metal foil, the second perforated region is arranged adjacent to the first perforated region, and the non-perforated region is the first. (Ii) Being placed adjacent to the perforated area ,
as well as
A perforated metal foil for a power storage device , wherein the thickness of the metal foil is 3 μm to 50 μm, and the material of the metal foil is an aluminum foil or a copper foil. The perforated metal foil for a power storage device according to claim 1, wherein the second perforation region is formed at a perforation rate of 30 to 70% as compared with the first perforation region. The perforated metal foil for a power storage device according to claim 1 or 2, wherein the width of the second perforated region is 2 mm or more and 50 mm or less. Claims 1 to 3, wherein the non-perforated region is provided at at least one end in the width direction of the metal foil, and the width of the non-perforated region is 2 mm or more and 50 mm or less. The perforated metal foil for a power storage device according to any one of the items. The perforated metal foil for a power storage device according to any one of claims 1 to 4, wherein the thickness of the metal foil is 3 μm to 50 μm. The perforated metal foil for a power storage device according to any one of claims 1 to 5, wherein the surface roughness (Ra) of the metal foil is 0.5 μm or less.

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