JP6351050B1 - Perforated metal foil for power storage device current collector, manufacturing method thereof, electrode, and battery including the electrode - Google Patents

Abstract

An object of the present invention is to propose a perforated metal foil for an electricity storage device current collector and a method of manufacturing the same, which can suppress the generation of metal pieces during processing, although it is a physical processing method. A perforated metal foil for an electricity storage device current collector according to the present invention includes a plurality of slit-like through-holes having an aspect ratio of 10 or more defined by long sides / short sides aligned in the length direction of the foil body. It is characterized by being formed. It is preferable that the foil main body has a strip shape, the length direction of the plurality of through holes is aligned in the length direction, and burrs are formed on the periphery of the opening of the through hole. It is preferable that a burr longer than 1/2 of the slit width of the through hole is formed at the periphery of the opening on the long side of the through hole. [Selection] Figure 1

Description

The present invention relates to a perforated metal foil for a current collector that is suitable for a power storage device current collector such as a secondary battery, a manufacturing method thereof, an electrode, and a battery including the electrode .

A metal foil is used as a current collector in power storage devices such as a lithium ion battery, a lithium ion capacitor, an electric double layer capacitor, and an all solid state battery. For example, in a lithium ion battery, an aluminum foil or a negative electrode current collector is used as a positive electrode current collector. Copper foil is mainly used as the electric body.
In these power storage devices, a perforated metal foil provided with through holes may be used as a current collector for the purpose of improving the pre-doping efficiency of lithium ions and preventing the active material layer from falling off.

  For example, as described in Patent Document 1 and Patent Document 2 below, a plurality of through holes are formed in the metal foil by passing the metal foil between a roll having irregularities on the surface and a smooth roll, and the metal foil and the active material It has been proposed to improve the adhesion of the.

  In addition, a method of forming a large number of through holes in a metal foil by etching as described in Patent Document 3 is also known.

Japanese Patent No. 4074689 Japanese Patent No. 583080 JP 2011-216364 A

However, Patent Document 2 discloses that when a punching process is performed by a physical method in which a metal foil is passed between a roll having an uneven surface and a smooth roll, fine metal pieces are generated during the punching process. Is clearly stated. When metal pieces of a certain size are mixed in the battery, there is a risk of short circuit inside, and there is a risk of abnormal heat generation in some cases. Although some documents report a method of removing the generated metal piece later, the internal short circuit is a fatal phenomenon in terms of battery safety, and it is desirable to suppress the occurrence itself.
In addition, in the technique using etching described in Patent Document 3, the risk of the above-mentioned metal piece generation is small, but since the manufacturing method is resist film formation, etching, and resist film removal, physical drilling is performed. There is a concern that the productivity is remarkably low as compared with the processing method, and the manufacturing cost as a current collector becomes extremely high.

In the present invention, the shape of the through-hole formed in the metal foil is devised, so that it is a physical processing method, but the perforated metal foil for the electricity storage device current collector that can suppress the generation of metal pieces during processing And a method of manufacturing the same. Another object of the present invention is to provide an electrode provided with an active material layer on the metal foil, and a battery including the electrode.

This invention is made | formed based on this knowledge, Comprising: It has the following structures.
The perforated metal foil for the electricity storage device current collector of the present invention is formed in the foil body with a plurality of slit-shaped through-holes having an aspect ratio of 10 or more defined by the long side / short side aligned in the length direction, A burr longer than ½ of the slit width of the through hole is formed on the entire periphery of the opening of each through hole .
In this invention, the said foil main body is strip | belt shape, and the structure by which the length direction of these through-holes was arrange | equalized in the length direction is employable.
In the present invention, the burr is formed so as to surround the entire periphery of the opening of the foil body, and the burr height on the end in the length direction of the through hole is the burr at the center in the length direction of the through hole. A configuration higher than the height can be adopted.

In the present invention, it can adopt a configuration having a plastic deformation portion to the burr.
In the present invention, a configuration in which the plurality of through holes are intermittently formed in the foil body at a pitch of 0.5 mm or more can be employed.
In the present invention, a configuration in which the short side of the through hole is 1 to 500 μm and the long side is 10 to 5000 μm can be adopted.
In the present invention, the through-holes are formed in a pair of parallel long side portions extending in the length direction thereof and end edges formed in a tapered shape on both ends in the length direction of the pair of long side portions. The structure which consists of parts can be adopted.

A method for manufacturing a perforated metal foil for an electricity storage device according to the present invention uses a rotary blade provided with a plurality of cutting edge portions intermittently through a recess along the outer peripheral edge of a disk-shaped main body portion. It is a slit-shaped through-hole having an aspect ratio of 10 or more defined by long sides / short sides intermittently in parallel with the metal foil in the direction of rotation at the individual blade edge portions while being pressed against the metal foil , A through hole having a burr longer than ½ of the slit width is formed at the periphery of the opening on the long side .
In the present invention, the blade edge portion is pressed in the thickness direction of the foil body, and the blade edge portion is pierced through the foil body while plastic deformation is applied to the foil body at the blade edge portion. The through hole can be formed while forming a burr having a plastically deformed portion obtained by plastically deforming a part of the main body.

In the present invention, the plurality of through holes can be intermittently formed in the foil body at a pitch of 0.5 mm or more.
In this invention, the short side of the said through-hole can be 1-500 micrometers, and a long side can be 10-5000 micrometers.
In the electrode of the present invention, a plurality of slit-shaped through-holes having an aspect ratio of 10 or more defined by the long side / short side are formed in the foil body with the length direction of each being aligned, and the entire periphery of the opening of each through-hole is formed. A burr longer than ½ of the slit width of the through hole is formed in the periphery, and the burr is crushed and smoothed, and an active material layer applied to both front and back surfaces of the metal foil is provided. It is characterized by that.
In the present invention, it is possible to adopt a configuration in which the active material layers formed on both the front and back surfaces of the foil main body are in close contact with each other through the through hole.
In the present invention, a configuration in which the plurality of through holes are intermittently formed in the foil body at a pitch of 0.5 mm or more can be employed.
In the present invention, a configuration in which the short side of the through hole is 1 to 500 μm and the long side is 10 to 5000 μm can be adopted.
The battery of the present invention can employ a configuration including the electrode according to any one of the preceding items.

According to the perforated metal foil for the electricity storage device current collector of the present invention, a plurality of slit-like through holes having an aspect ratio of 10 or more are formed, and the entire circumference of the opening periphery of each through hole is longer than ½ of the slit width. Since the burr is provided, it is possible to suppress the generation of metal pieces during drilling. Moreover, when an active material is applied to both the front and back surfaces of the metal foil, the active materials on the front and back surfaces are in close contact with each other due to the presence of the through-holes, and the adhesion of the active material to the metal foil can be improved.
In the case of a strip-shaped metal foil, the tension at the time of winding or unwinding is applied in the length direction, but the long side of the through hole is aligned along the length direction of the metal foil. Thus, it is possible to provide a metal foil configured to withstand the tension during winding or unwinding.
Also, as the electrode of the electricity storage device, when laminated and wound and there is no hole in the current collector foil, when the electrolyte between the electrodes is dried up, the resistance of that part tends to increase significantly, If there is a through hole in the collector foil, the electrolytic solution capillarity through the through-hole from the adjacent layers, it is possible to penetrate the moiety de Lai up, it is possible to suppress an increase in the electrode resistance become. Therefore, partial dry-up of the electrolytic solution is unlikely to occur, which leads to improvement in cycle characteristics when used for a long period of time.
In particular, in the case of a wound electrode, the heat cannot be radiated from the central portion of the electricity storage device due to the structure, and the heat generation increases, and the resistance increases easily due to the electrolyte dry-up in this portion. When the through-hole is opened in the electric body, the electrolytic solution easily permeates from the outer peripheral portion, and it is difficult to increase the resistance of the electrode in the central portion, and the resistance as the entire power storage device is difficult to increase.
In the metal foil of the present invention, the generation of metal pieces can be suppressed at the time of forming the through-hole. Therefore, when an active material layer is formed on both surfaces of the metal foil to form an electrode and a battery equipped with this electrode is formed, It is possible to provide a battery that is free from the risk of an internal short circuit due to the presence.

The top view of the perforated metal foil for electrical storage device electrical power collectors of 1st Embodiment of this invention. The partial enlarged plan view which shows an example of the arrangement | sequence state of the through-hole currently formed in the metal foil. The partial enlarged plan view for demonstrating the shape of the through-hole currently formed in the metal foil. The enlarged schematic diagram which shows the example of the through-hole currently formed in the metal foil. The expanded perspective view which looked at the example of the through-hole currently formed in the metal foil from the surface side of foil. The expanded perspective view which looked at the example of the through-hole currently formed in the metal foil from the back surface side of foil. The side view for demonstrating the state which forms a through-hole by the blade edge part of a tool in the metal foil. The perspective view which shows an example of the through-hole formation state by the tool used when forming a through-hole in the metal foil. The top view which shows an example of the tool used when forming a through-hole in the metal foil. The side schematic diagram which shows an example of the manufacturing apparatus used in order to form a through-hole continuously in a strip | belt-shaped metal foil. The side view which shows an example of the manufacturing apparatus which added the function which forms a through-hole continuously in a strip | belt-shaped metal foil, and also crushes a burr | flash. The top view of the perforated metal foil for electrical storage device electrical power collectors of 2nd Embodiment of this invention. 1 shows an example of a laminate type secondary battery using a metal foil according to the present invention as a positive electrode current collector, (A) is a perspective view for disassembling a part of the secondary battery and showing the entire configuration; (B) is an enlarged perspective view showing a positive electrode current collector, a negative electrode current collector, and an active material applied thereto. The side view which shows an example of the tool used when manufacturing the conventional perforated metal foil. The figure which shows the 3D image test result of the through-hole surface part currently formed in the metal foil manufactured in the Example. The figure which shows the 3D image test result of the through-hole back surface part currently formed in the metal foil manufactured in the Example. The microscope picture which planarly viewed the through-hole currently formed in the metal foil manufactured in the Example. The photograph which shows the specific example of the through-hole of the actual example of the through-hole formed in the metal foil manufactured in the Example, and a comparative example. This figure shows the state of occurrence of metal pieces adhering to a rubber mat laid under the metal foil when the metal foil is manufactured. (A) shows the region (left side of the photograph) formed with the metal foil of the comparative example. The photograph which compares and shows the area | region (photograph right side) which formed the metal foil of an example, (B) is a photograph which expands and shows the area | region shown to (A) partially. The other form of the blade edge | tip part of the tool used when forming a through-hole in the metal foil is shown, (A) is a side view which shows a 2nd form, (B) is a side view which shows a 3rd form. . FIG. 6 shows still another form of the cutting edge portion of the tool used when forming a through hole in the metal foil, (A) is a front view showing a fourth form, and (B) is a front view showing a fifth form. (C) is a front view showing a sixth embodiment, (D) is a front view showing a seventh embodiment. The rotary blade and blade edge | tip part used when forming a through-hole in the metal foil are shown, (A) is a figure which shows the other form of a rotary blade, (B) is the side surface which shows the 8th form of a blade edge | tip part. (C) is a side view showing a ninth form of the blade edge part, (D) is a side view showing an eighth form of the blade edge part.

A specific embodiment of a perforated metal foil for an electricity storage device according to the present invention will be described with reference to the drawings. In addition, in the drawings used in the following description, in order to make the features easy to understand, there are cases where the portions that become the features are enlarged for the sake of convenience, and the dimensional ratios of the respective components are not always the same as the actual ones. Absent.
FIG. 1 shows a perforated metal foil 1 for an electricity storage device current collector according to this embodiment. A slit-shaped (substantially rectangular in plan view) through-hole 2 is formed in a strip-shaped foil main body 1A along its length direction. A plurality of rows are formed intermittently and at a predetermined interval.
FIG. 1 is a schematic diagram showing the overall configuration. In order to emphasize the formation position of the through hole 2, the through hole 2 is displayed in a black rectangle, but the through hole 2 is shown in FIGS. 2 and 3. In this way, the foil body 1 is formed as a slit-like hole. The detailed shape of the specific through-hole 2 formed in the foil body 1A will be described later in detail with reference to FIGS.

The foil body 1 may be made of any metal foil such as aluminum or aluminum alloy foil, copper or copper alloy foil, nickel or nickel alloy foil, silver or silver alloy foil, for example.
When the metal foil 1 of the present embodiment is applied as a current collector of an electricity storage device such as a lithium ion secondary battery, if it is used as a positive electrode current collector, an aluminum or aluminum alloy foil can be used. If used as an electric body, a copper or copper alloy foil can be used.
The metal foil 1 is not limited to a current collector of a lithium ion secondary battery, but can be widely applied as a current collector of various power storage devices such as a lithium ion capacitor, an electric double layer capacitor, or an all solid state battery.

The through-hole 2 formed in the metal foil 1 has a long side 2a and a short side 2b as shown in an enlarged view in FIG. 2 or FIG. 3, and all have substantially the same shape, all have substantially the same major diameter, and all have substantially the same. The short-diameter through-hole 2 is formed, and the aspect ratio that can be defined by the long side (2a) / short side (2b) of the through-hole 2 is 10 or more. When the aspect ratio of the through hole 2 is less than 10, the ratio of the long side / short side becomes small and the through hole 2 becomes a shape close to a square hole, and the foil main body 1A is configured at the time of drilling using a tool described later. This is not desirable because the metal is broken to produce fine metal pieces. For this reason, increasing the aspect ratio of the through hole 2 is more effective in reducing the generation of metal pieces.
The upper limit of the aspect ratio of the through hole 2 is not particularly specified, but the upper limit of the aspect ratio is preferably set to about 200 in consideration of ease of workability and ease of handling when forming the through hole 2 in the foil body 1A. .

When the metal foil 1 is used for the secondary battery current collector, the long side 2a of the through hole 2 is preferably in the range of 10 μm to 5000 μm, and the short side 2b is preferably in the range of 1 μm to 500 μm. In the aforementioned range, the long side 2a is more preferably in the range of 500 to 3000 μm, and the short side 2b is more preferably in the range of 5 to 100 μm.
In the specification of the present application, when a numerical range is defined, it means a range including an upper limit and a lower limit unless otherwise noted. Therefore, the range of 10 μm to 5000 μm means a range of 10 μm to 5000 μm.

When the metal foil 1 is used for the secondary battery current collector, the pitch of the through holes 2 intermittently arranged in a row in the length direction of the foil body 1A (from the tip of one through hole 2 to the next through hole 2). (Distance to tip: see FIGS. 2 and 3) As an example, P is preferably 0.5 mm or more. However, this limitation is the case where the through hole 2 is formed by cutting into the foil body 1A using a tool described later, and when the pitch P is too small, the metal foil 1 is taken up by a roll or unwound by a roll. In addition, there is a risk of deformation or breakage of the foil main body 1A, and this is a pitch limitation in consideration of a possibility that the through holes 2 adjacent to each other are connected in a row. For this reason, when there is no fear of breakage or deformation of the foil body 1A, a pitch P of less than 0.5 mm may be adopted.
Note that the value of the pitch P does not have to be constant as in this embodiment, and may vary periodically or change randomly.

  The thickness of the metal foil 1 is desirably in the range of 1 μm to 40 μm. If the metal foil is thinner than 1 μm, the strength is insufficient and may be deformed during winding or unwinding, and if it exceeds 40 μm, the merit as a current collector for a secondary battery is reduced.

2 and 3, the metal foil 1 is formed with a plurality of through holes 2 with the above-described pitch P, with the long sides 2a aligned in the length direction of the strip-shaped foil body 1A. A plurality of rows of through holes 2 are formed at a predetermined interval T in the width direction.
The through holes 2 arranged in the width direction of the foil body 1A are alternately arranged in the width direction of the foil body 1A. In this example, the pitch P is smaller than the length of the long side 2 a of the through hole 2. For this reason, the through-hole 2 of the adjacent row | line | column is arrange | positioned in the side of the area | region between the through-holes 2 and 2 adjacent by the predetermined pitch P in the length direction of 1 A of foil main bodies. As an example, when the region where the three through holes 2 are adjacently disposed is viewed in plan as shown in FIG. 2 or FIG. 3, the figure connecting the longitudinal center points of the three through holes 2 is an isosceles triangle or an equilateral triangle. It is possible to adopt such an arrangement. This arrangement is an example, and it is needless to say that another arrangement may be adopted as the arrangement of the through holes 2.

In the metal foil 1 shown in FIG. 1, eleven rows of through holes 2 are formed in the width direction of the foil body 1A. In FIG. 2, three rows of through holes 2 are enlarged, and in FIG. Is enlarged. The interval T between the rows of the through-holes 2 can be selected from a range of 1 mm to 20 mm, for example.
If the pitch P and the interval T are too small, the strength of the metal foil 1 is lowered, and therefore, when the tension is applied in the length direction of the metal foil 1, the metal foil 1 may be deformed. For example, when manufacturing a secondary battery, since it is necessary to perform a process such as winding or unwinding while applying tension to the metal foil 1, the metal foil 1 is not deformed during winding or unwinding. It is necessary to adopt such a pitch P and interval T.

4 to 6 are detailed enlarged views when the through hole 2 shown in FIGS. 1 to 3 is actually formed on the foil main body 1A using a cutting edge portion of a tool described later.
The through-hole 2 in this example includes a long side 2B parallel to each other in the opening 2A, and a short side 2C formed in a U-shaped tapered shape on both ends in the length direction of the long side 2B. As shown in FIG. 5, burrs 3 are formed so as to protrude from the front surface side to the back surface side of the foil body 1A on almost the entire periphery of the opening 2A. The burr 3 includes a long side burr part 3A protruding from the long side part 2B of the opening 2A and a short side burr part 3B protruding from the short side part 2C. The two long side burr parts 3A and the two short sides The burr 3B surrounds the entire back surface of the opening 2A. As shown in FIG. 4, the length of the through hole 2 in the plan view of the through hole 2 can be expressed as a, and the slit width of the through hole 2 (interval between the opposing long side portions 2 </ b> B: along the vertical direction in FIG. 4. The length of the short side portion 2C) can be expressed as D.

These burrs 3 are formed by penetrating the foil main body 1A in the thickness direction by a cutting edge portion of a tool described later and partially plastically deforming the foil main body 1A when penetrating.
For this reason, the height (length) of the long side burr portion 3 </ b> A is formed to be larger than ½ of the slit width of the through hole 2. Further, the height (length) of the long side burr portion 3A and the height (length) of the short side burr portion 3B are substantially equal. The reason why the height of the long side burr portion 3A is formed to be larger than ½ of the slit width of the through hole 2 is when a part of the foil body 1A is penetrated in the thickness direction at the blade edge portion of the tool described later. This is a result of extending the metal material constituting the foil body 1A by plastic deformation.
The fact that the length of the long side burr portion 3A is formed to be larger than ½ of the slit width of the through hole 2 is that the foil main body 1A is penetrated in the thickness direction by using a blade edge portion of a tool to be described later. It shows that the hole 2 was formed.

FIG. 7 shows an example of a state in which the through-hole 2 is formed by piercing the foil body 1 using the cutting edge portion 10G of the tool 10, and FIG. 8 is suitable for use when forming the through-hole 2 in the foil body 1A. An example of a simple tool is shown.
A tool 10 shown in FIG. 8 is a tool having a disk-shaped rotary blade 10D that is rotatably provided by a shaft portion 10B on a part of a support shaft 10A.
A plurality of convex cutting blades 10F are alternately formed at regular intervals on the outer peripheral edge portion of the rotary blade 10D via a plurality of concave portions 10E in the circumferential direction, and a cutting edge portion 10G is formed at a tip portion of the cutting blade 10F. The rotary-type clearance blade is configured.

  While the rotary blade 10D of the tool 10 is pressed at right angles to the foil body 1A of the metal foil 1 and processed so as to penetrate the foil body 1A with the individual blade edge portions 10G, the rotary blade 10D is moved along the length direction of the foil body 1A. As shown in FIG. 8, a plurality of through-holes 2 can be intermittently formed in a row in the foil body 1A. Prior to this processing, it is preferable to arrange a receiving material such as a rubber sheet on the back surface side of the foil main body 1A so as to provide a cushion material when the blade edge portion 10G penetrates the foil main body 1A.

  FIG. 7 shows a state in which the blade edge portion 10G is pulled out from the foil body 1A after the blade edge portion 10G penetrates the foil body 1A in the thickness direction to form the through-hole 2. By penetrating the foil body 1A with the cutting edge portion 10G in the thickness direction, a through hole 2 having a slit width D can be formed in the foil body 1A and plastically deformed so as to extend a metal material on the back side of the foil body 1A. A burr 3 can be formed. Therefore, in the burr 3, the height (length) H of the long side burr part 3A is formed to be larger than ½ of the slit width D. In addition, since the short side burr | flash part 3B is similarly formed in the short side side of the through-hole 2 with a plastic deformation, the short side burr | flash part 3B becomes the height (length) equivalent to 3A of long side burr | flash parts. It is formed.

If one row of through-holes 2 is formed as shown in FIG. 8, the necessary rows of through-holes 2 are sequentially formed at different positions in the width direction of the foil body 1A using the rotary blade 10D of the tool 10. Thus, the metal foil 1 having the configuration shown in FIG. 1 can be obtained.
If the through-hole 2 is formed in the foil body 1A using the tool 10 having the rotary blade 10D shown in FIGS. 8 and 9, the burr 3 is formed in the foil body 1A using the blade edge portion 10G. Since the through-hole 2 can be formed, the metal foil 1 having many through-holes 2 having a target aspect ratio and a target size can be easily manufactured. Further, if the through-hole 2 having an aspect ratio of 10 or more is formed in the foil body 1A by piercing using the blade edge portion 10G, the material of the foil body 1 is stretched by the blade edge portion 10G and plastically deformed, and then the through-hole 2 is formed. Since the burr 3 is generated and formed, the through hole 2 can be formed without generating foreign matters such as fine metal pieces individually. For this reason, the metal foil 1 having no foreign matter such as a fine metal piece is suitable for a current collector of a power storage device such as a secondary battery, and provides a high-quality current collector without fear of an internal short circuit. it can.

FIG. 10 is a side view showing an example of a manufacturing apparatus suitable for use in the case where a plurality of rows of through holes 2 are continuously formed on a long strip-shaped foil body 1A.
The manufacturing apparatus 15 of this example has an unwinding reel 16 that can unwind the strip-shaped foil body 1 </ b> A and a take-up reel 17 that can wind up the foil body 1 </ b> A, and between the unwinding reel 16 and the take-up reel 17. A pressing roll 18 and a rotary blade 19 are provided on the front side, and an adjustment reel 20 is provided on the front and rear sides thereof.
The rotary blade 19 has a configuration in which a plurality of blade edges 19a are provided on the outer peripheral portion, and a plurality of rotary blades 19c provided via recesses 19b are stacked in a necessary thickness direction. The number of the rotary blades 19c stacked corresponds to the number of rows of the through holes 2 formed in the width direction of the foil body 1A.
The pressing roll 18 is a roll having an elastic body layer on the outer peripheral portion or made entirely of an elastic body. When the strip-shaped foil body 1A is pierced by the blade edge portion 19a of the rotary blade 19, the tip of the blade edge portion 19a is elastic. It is a cushion roll for receiving.

The strip-shaped foil body 1A wound around the unwinding reel 16 is fed out, passed between the rotary blade 19 and the pressing roll 18 via one adjustment reel 20, and taken up via the other adjustment reel 20. Take up with reel 17. By this operation, a plurality of rows of through holes 2 can be intermittently and simultaneously formed in the foil main body 1A that has passed between the rotary blade 19 and the pressing roll 18 by the plurality of cutting edge portions 19a of the rotary blade 19.
If the through holes 2 are formed in the foil body 1A with a configuration in which the plurality of rotary blades 19 are arranged in parallel, the plurality of through holes 2 in a state of being accurately aligned at a predetermined interval in the width direction of the foil body 1A can be formed. By using the manufacturing apparatus 15 shown in FIG. 10, the through holes 2 in a state of being uniformly and accurately arranged in the foil body 1A can be formed.

FIG. 11 is a side view showing another example of a manufacturing apparatus suitable for use in the case where a plurality of rows of through holes 2 are continuously formed on a long strip-shaped foil body 1A. In the manufacturing apparatus 21 shown in FIG. 11, the same components as those of the manufacturing apparatus 15 shown in FIG. 10 are denoted by the same reference numerals, and the description of the same components is omitted.
The manufacturing apparatus 21 of this example is characterized in that light pressure lowering rolls 22 and 22 are arranged between the installation position of the rotary blade 19 and the pressing roll 18 and the adjustment reel 20 on the take-up reel 17 side.
These lightly rolling rolls 22 and 22 lightly roll the foil main body 1A, and crush the burrs 3 provided in the plurality of through holes 2 formed in the foil main body 1A by the rotary blade 19 and the pressing roll 18 to obtain the foil. It has a function of smoothing the main body 1A.

FIG. 12 shows a metal foil 23 according to the second embodiment. In the metal foil 23 according to the second embodiment, through holes 24 formed at a constant pitch along the length direction are respectively provided in the width direction. Are formed in a line.
As shown in the structure of the second embodiment, the through holes 24 may be formed so as to be aligned in the width direction of the metal foil 23, or may be formed alternately as in the previous embodiment. In addition, a free arrangement may be used, but in any case, the metal foil 23 is preferably formed along the length direction.

The metal foil 1 manufactured by the tool 10 or the manufacturing apparatuses 15 and 21 described above can be applied as, for example, an electrode foil of a lithium ion secondary battery described below based on FIG.
The secondary battery 25 shown in FIG. 13 includes a positive electrode current collector 31 made of an aluminum or aluminum alloy foil body and separators 28 and 29 around tab leads 26 and 27, and a negative electrode current collector made of a copper or copper alloy foil body. The electric body 30 is wound. A positive electrode active material layer 33 is applied to both surfaces of the positive electrode current collector 31, and a negative electrode active material layer 32 is applied to both surfaces of the negative electrode current collector 30.
The positive electrode current collector 31 is applied with the metal foil 1 composed of the foil body 1A in which the above-described through holes 2 are aligned, and the negative electrode current collector 30 is composed of the metal foil composed of the foil body 1A in which the above-described through holes 2 are aligned. The foil 1 is applied. Alternatively, only one of the positive electrode current collector 31 and the negative electrode current collector 30 may be the metal foil 1 made of the foil body 1A.
In the secondary battery 25 shown in FIG. 13, the slits 2 of the positive electrode current collector 31 and the negative electrode current collector 30 are formed in parallel to these winding directions. The slot 2 is formed along the direction in which the electrode is wound in this way, which is preferable because the slit 2 retains its shape when a tensile stress is applied when the metal foil is wound.

In the positive electrode current collector 31 and the negative electrode current collector 30 formed of a foil body in which a plurality of the through holes 2 are formed, the active material layer 32 or the active material layer 32 is formed on both surfaces of the current collectors 30 and 31 provided with the plurality of through holes 2. As a result of the material layer 33 being provided, the active materials provided on both surfaces of the current collectors are in close contact with each other, so that the adhesion of the active material layers 32 and 33 to the current collectors 30 and 31 is improved.
Further, when an active material is applied to the positive electrode current collector 31 and the negative electrode current collector 30, tension is applied to the foil main body 1A of the positive electrode current collector 31 and the foil main body 1A of the negative electrode current collector 30, respectively. Since the holes 2 are formed under the above-described conditions and the strength necessary for unwinding and winding is maintained, the active material can be applied without causing any trouble such as breakage or deformation of the foil body 1A.

If it is the above-mentioned metal foil 1, the aspect ratio which can be prescribed | regulated by the long side (2a) / short side (2b) of the through-hole 2 shall be 10 or more, and the through-hole 2 with the above-mentioned tool 10 or the manufacturing apparatuses 15 and 21. Therefore, a secondary battery in which unnecessary conductive foreign matters such as fine metal pieces are not attached to the metal foil 1 and the internal short circuit due to the conductive foreign matters of the current collector does not occur. Can be configured.
The long side 2a of the through hole 2 is in the range of 10 μm to 5000 μm, the short side 2b is in the range of 1 μm to 500 μm, and the long side 2a of the through hole 2 is aligned in the length direction of the foil body 1A. Since the thickness is 1 to 40 μm and the through holes 2 are intermittently formed in the foil body at a pitch of 0.5 mm or more, the practical strength that can withstand the application of tension during unwinding and winding during secondary battery production Have
In addition, in the case of the wound current collectors 30 and 31 as shown in FIG. 12, heat cannot be radiated from the central portion of the electricity storage device due to the structure, and heat generation increases, and the electrolyte solution in this portion is dried up. Increase in resistance easily occurs. However, when a plurality of through-holes 2 are formed in the current collectors 30 and 31 of the electrodes, the electrolytic solution can easily penetrate through the through-holes 2 from the outer peripheral portion, and it is difficult to increase the resistance of the electrode in the central portion. The resistance of the secondary battery as a whole is less likely to increase.

  In addition, when a through-hole is opened in a metal foil with a conventional uneven roll, the metal foil sandwiched between the uneven rolls is punched so as to tear, so inevitably many fine metal pieces are generated. However, there is a risk of short circuit. On the other hand, if the through-hole 2 is formed by the tool 10 or the manufacturing apparatuses 15 and 21 described above, a part of the metal foil is plastic-worked, but the plastic-worked part is left as a burr, and one part of the plastic-worked part is left. Since the through hole 2 is formed by cutting the portion, the through hole 2 can be formed without generating unnecessary metal pieces. For this reason, the metal foil which the adhesion of the metal piece has not arisen can be obtained.

Examples of the present invention will be described below, but the present invention is not limited to these examples.
An aluminum foil (tempered: H18) made of JIS A 1085 alloy with a thickness of 15 μm and having a width of 200 mm × length of 300 mm was laid on a rubber mat, and a tool equipped with a rotary blade with slits shown in FIGS. 20 rows of through holes having the sizes shown in Table 1 were formed at the pitches shown in Table 1 below.
Prepare a rotary blade with various changes so that the long side length, short side length, and pitch between the blade edges are the values shown in Table 1, and form through holes in the aluminum foil under the same conditions as above. did. Moreover, about a comparative example, foil body using the tracing wheel 37 which has the cone-shaped blade edge | tip with the pointed tip through the arm part 36 on the front end side of the handle | steering-wheel part 35 shown in FIG. A through-hole was formed in. The thickness of the blade portion of the rotary blade used was 0.5 mm, and the cross-sectional shape of the blade edge was the blade edge shape shown in FIG. 7 with a blade edge angle of 20 °.
In Table 1, a through hole having a long side of 2700 μm and a short side of 8 μm is formed in the aluminum foil using a gap blade using a rotary blade having a blade edge portion having substantially the same length and width as this through hole. . For the other through holes, the size of the cutting edge portion of the gap blade corresponds to the size of the through hole.

A positive electrode slurry (positive electrode active material) composed of a positive electrode active material, a conductive material, a binder, and a diluent shown below is formed on each aluminum foil of Examples 1 to 5 in Table 1 so as to have a thickness of 50 μm. It apply | coated on each aluminum foil before drilling, and it dried at 130 degreeC for 1 hour, and obtained the electrode. About Examples 1-5 and a comparative example, the positive electrode slurry is apply | coated to both surfaces of foil.
Positive electrode active material Lithium iron phosphate (average particle size: 1μm)
Conductive material Acetylene Black (AB)
Binder Polyvinylidene fluoride (PVDF)
Diluent N-methyl-2-pyrrolidone (NMP)
Mixing ratio of each component (weight ratio) Positive electrode active material: AB: PVDF = 85: 8: 7

  A strip test piece having a width of 15 mm was cut out for each electrode, a 90 ° peel test was performed, and a peel strength (N / 15 mm) was measured. When the peel strength of the foil before perforation was set to 1, 0 or more and less than 1 was evaluated as x, 1 or more and less than 2 as ◯, and 2 or more as 以上. The results are listed in Table 1.

  A strip test piece having a width of 15 mm and a length of 200 mm was prepared for each of the aluminum foils before Examples 1 to 5, the comparative example, and the holes were formed. The distance between chucks of the universal tensile testing machine (manufactured by Shimadzu Corporation) was set to 100 mm, and the maximum load (N / 15 mm) measured until the foil broke was calculated. The results are listed in Table 1.

The number of aluminum pieces generated when a certain number of through-holes were opened in the aluminum foil was measured to evaluate the difficulty of the generation.
The form of the through hole depends on the type of blade used for drilling, and here, there are three types of “Examples 1 and 2”, “Examples 3 and 5”, and a comparative example. Thousands of through-holes each having three types of dimensions were prepared on an aluminum foil of JIS A 1085 alloy tempered H18 having a thickness of 15 μm, and the number of aluminum pieces generated at that time was counted. At this time, there is a possibility that very fine aluminum powder that is difficult to observe visually is also generated, but here, only aluminum pieces having a diameter of about 0.1 μm or more were counted.
Less than 50 was evaluated as ◎, 50 or more and less than 200 as ○, 200 or more and less than 500 as Δ, and 500 or more as ×. The results are listed in Table 1.

As shown in Table 1, the metal foils of Examples 1 to 8 in which through holes having an aspect ratio (long side / short side) of 12 to 338 were formed in rectangular through holes had high tensile strength, and the active material layer was closely attached. It was excellent in properties and no aluminum pieces were observed. About the adhesiveness of the active material, since it has applied on both surfaces of the electrical power collector, the peeling strength has increased.
On the other hand, the metal foil of Comparative Example 1 was a sample having an aspect ratio of 1, but the tensile strength was slightly reduced and generation of aluminum pieces was observed.
In addition, it can be presumed that the active material adhesion in the sample of Example 4 and the sample of Comparative Example 1 is both ◯ because of the influence of the pitch difference in the short side direction.
The sample of Example 6 was an example in which the pitch of the through holes was reduced, but the tensile strength tended to decrease slightly. The sample of Example 7 is an example in which the long side and the short side of the through-hole are enlarged, but the generation of aluminum pieces tends to increase although it is within a good range. The sample of Example 8 was a sample with a long side increased, but the tensile strength tended to decrease compared to Examples 1-5.
Comparative Example 2 was a sample having an aspect ratio of 7, but generation of aluminum pieces was observed.

FIG. 15 shows the 3D image inspection result (by VK-X100 made by Keyence Corporation) of the through hole of the sample of Example 1 shown in Table 1 as viewed from the front side, and FIG. 16 shows the back side of the through hole of the same example. FIG. 17 shows an enlarged view (magnification 100 times) when the through hole of the same example is viewed in plan. In Example 2, a 3D image result almost equivalent to that in Example 1 was obtained.
The through-holes shown in FIGS. 15 to 17 are slit-like through-holes having a length of 2.7 mm (2700 μm) and a width of 8 μm, and burrs having a height of about 70 μm are formed all around the through-hole opening.
In addition, when the burr height was investigated about each Example, Example 2 (70 micrometers), Example 3, 4 (120 micrometers), Example 5 (130 micrometers), Example 6 (120 micrometers), Example 7 (150) To 250 μm) and Example 8 (120 μm).

FIG. 18 shows a comparative example 1 sample in a left half region of an aluminum foil (tempered: H18) made of JIS A 1085 alloy having a thickness of 15 μm and having a width of 220 mm and a length of 300 mm on a rubber mat. A state in which a through hole is formed using the tool used in Examples 1 and 2 in the right half region is shown.
In the left half region of the aluminum foil shown in FIG. 18, round holes having an aspect ratio of 1 are formed by using the tracing wheel shown in FIG. Formed with. A substantially rectangular through-hole was formed in the right half region of the aluminum foil in the same manner as in Examples 1 and 2 with an interval of 7 mm for each row and a pitch of 1 mm.

FIG. 19 shows the result of observing the aluminum pieces remaining on the surface of the rubber mat by removing the aluminum foil after the formation of the through-hole shown in FIG. 18 and FIG. 19 (B). ) Shows the result of photographing different positions on the rubber mat.
19A and 19B, a region surrounded by a rectangular frame on the right side indicates a region where the through hole used in Examples 1 and 2 is formed, and a region on the left side of each drawing is used in Comparative Example 1. The area | region which formed the through-hole is shown.
As is clear from the comparison shown in FIG. 19, if a slit-shaped through-hole having an aspect ratio of 10 or more is formed using the rotary type cutting edge tool shown in FIGS. 8 and 9, almost all aluminum pieces are generated. You can see that they are not.

This means that the aluminum piece does not adhere to the aluminum foil in which the through hole is formed. Therefore, when this aluminum foil is used as a current collector of an electricity storage device such as a secondary battery, an aluminum piece that may cause an internal short-circuit is removed. This means that it is not mixed into the electricity storage device (battery). In addition, as shown in FIG. 19, that many aluminum pieces adhered on the rubber mat means that a considerable number of aluminum pieces are also adhered to the back surface side of the obtained aluminum foil.
Therefore, it was found that an electrode foil for a current collector having high strength, excellent active material adhesion, and no generation of aluminum pieces can be provided.

By the way, the side surface shape of the cutting edge part 10G of the tool 10 shown so far shown in FIGS. 7-11 and the side surface shape of the blade edge part 19a of the rotary blade 19 are examples, and are for forming the through-hole which concerns on this invention. The shape of the blade edge portion is not limited to these examples. For example, it may be a side isosceles trapezoidal cutting edge portion 40 in which R is formed at each corner portion shown in FIG. 20 (a), or a side hook-shaped outline having a round cutting edge shown in FIG. 20 (b). The cutting edge 41 may be used. The shape of the side surface of the blade edge portion is not particularly limited as long as it can form a through hole having a required width and length.
Further, the cross-sectional shape of the blade edge portion may be a double-blade type blade edge portion 42 as shown in FIG. 21 (A) or a blade edge portion 42 having a blade edge angle of about 90 °, or a two-stage blade type as shown in FIG. 21 (B). The blade edge portion 43 may have a blade edge angle of about 120 ° and a second blade edge angle of about 50 °. Furthermore, a double-edged blade type as shown in FIG. 21C and a blade edge part 44 having a cutting edge angle of about 25 °, and a two-stage blade type as shown in FIG. Any cross-sectional shape such as a blade edge portion 45 having a blade edge angle of about 70 ° at the second stage may be used. The angle of the blade edge is not particularly limited, and the cross-sectional shape of the blade edge portion is not particularly limited as long as it can form a through-hole having a required width and length.

Further, in the previous example, the tool 10 or the rotary blade 19 was used as a tool for forming a through hole in the metal foil, but a plurality of cutting edges are provided on the outer periphery of the rotating disk 46a shown in FIG. A configuration in which the rotary blade 46 provided with the portion 46 b is provided so as to be movable up and down with respect to the metal foil 47 can be adopted. In FIG. 22 (A), a plurality of cutting edge portions shown in FIG. 20 or FIG. 21 are intermittently formed on the outer periphery, but in the drawing, the description of each cutting edge portion is omitted and only an outline is described.
The rotation center axis of the rotary blade 46 is supported so as to be movable up and down, and the tape-shaped metal foil 47 is moved in the length direction while the rotary blade 46 is reciprocated up and down, whereby a through hole 47a is formed in the metal foil 47. Can be formed intermittently.

Further, as shown in FIG. 22B, the rotary blade 46 may use a cutting edge tool 48 having a configuration in which a cutting edge portion 48c is provided only on one side of a rectangular block portion 48b having a central shaft portion 48a. As shown in (C), a cutting edge tool 49 having a cutting edge portion 49c on each end of a columnar block portion 49b having a central shaft portion 49a may be used. Further, as shown in FIG. 22D, a cutting edge tool 50 having a configuration in which three cutting edge portions 50c are provided around a triangular block portion 50b including a central shaft portion 50a may be used.
Using the cutting edge tools 49 and 50 shown in FIGS. 22 (C) and 22 (D), they are reciprocated up and down while intermittently rotating, and the cutting edge portions 49c and 50c are intermittently pressed against the tape-shaped metal foil 47. A desired perforated metal foil can be manufactured by forming the through-hole 47a.
As described above, various shapes can be adopted for the tool and the blade edge portion for forming the through hole in the metal foil.

DESCRIPTION OF SYMBOLS 1 ... Metal foil, 2 ... Through-hole, 2A ... Opening part, 2B ... Long side part, 2C ... Short side part, 2a ... Long side, 2b ... Short side, 3 ... Burr, 3A ... Long side burr part, 3B ... Short side burr section, 10 ... tool, 10F ... cutting blade, 10G ... cutting edge section, 15, 21 ... manufacturing device, 16 ... unwinding reel, 17 ... take-up reel, 18 ... pushing roll, 19 ... rotary blade, 19a ... blade edge part, 19b ... concave part, 23 ... metal foil, 24 ... through-hole, 25 ... secondary battery, 26, 27 ... tab lead, 28, 29 ... separator, 30 ... negative electrode current collector, 31 ... positive electrode current collector, 32 ... Negative electrode active material layer , 33 ... Positive electrode active material layer , 40, 41 ... Blade edge part, 42, 43, 44, 45 ... Blade edge part, 46 ... Rotary blade, 48c, 49c, 50c ... Blade edge part.

Claims (16)

  A plurality of slit-shaped through-holes having an aspect ratio of 10 or more defined by the long side / short side are formed in the foil body with the length direction of each being aligned, and the through-holes are formed around the entire periphery of the opening of each through-hole. A perforated metal foil for an electricity storage device current collector, wherein burrs longer than 1/2 of the slit width are formed.   2. The perforated metal foil for an electricity storage device current collector according to claim 1, wherein the foil main body has a strip shape, and the length direction of the plurality of through holes is aligned in the length direction thereof.   The burr is formed so as to surround the entire periphery of the opening of the foil body, and the burr height at the end in the longitudinal direction of the through hole is made higher than the burr height at the center in the length direction of the through hole. The perforated metal foil for an electricity storage device current collector according to claim 1 or 2, wherein the metal foil is perforated.   The perforated metal foil for an electricity storage device current collector according to any one of claims 1 to 3, wherein the burr has a plastically deformed portion.   5. The perforated metal for an electricity storage device current collector according to claim 1, wherein the plurality of through holes are intermittently formed in the foil body at a pitch of 0.5 mm or more. Foil.   The perforated metal foil for an electricity storage device current collector according to any one of claims 1 to 5, wherein the through-hole has a short side of 1 to 500 µm and a long side of 10 to 5000 µm.   The through-hole is composed of a pair of parallel long side portions extending in the length direction and edge portions formed in a tapered shape on both ends in the length direction of the pair of long side portions. A perforated metal foil for an electricity storage device current collector according to any one of claims 1 to 6, wherein: Using a rotary blade having a plurality of cutting edge portions intermittently through a recess along the outer peripheral edge of the disk-shaped main body, the metal blade is rotated by pressing the rotating blade against a metal foil and the individual cutting edge portions A slit-shaped through-hole having an aspect ratio of 10 or more, which is defined by the long side / short side, intermittently in parallel with the rotation direction of the foil, and the opening side periphery of the long side has a slit width of ½ A method for producing a perforated metal foil for an electricity storage device current collector , wherein a through-hole having a long burr is formed. A part of the foil body on the piercing side by pressing the blade edge part in the thickness direction of the foil body and passing the blade edge part through the foil body while plastic deformation of the foil body at the blade edge part. 9. The method for producing a perforated metal foil for an electricity storage device current collector according to claim 8 , wherein the through-hole is formed while forming a burr having a plastically deformed portion obtained by plastically deforming the material. The method for producing a perforated metal foil for an electricity storage device current collector according to claim 8 or 9 , wherein the plurality of through holes are intermittently formed in the foil body at a pitch of 0.5 mm or more. The short side of the through-hole 1 to 500 [mu] m, the long sides of the electric storage device current collector perforated metal foil according to any one of claims 8 to claim 10, characterized in that the 10~5000μm Production method. A plurality of slit-shaped through-holes having an aspect ratio of 10 or more defined by the long side / short side are formed in the foil body with the length direction of each being aligned, and the through-holes are formed around the entire periphery of the opening of each through-hole. A burr longer than ½ of the slit width is formed, and the burr is crushed and smoothed , and the metal foil is provided with an active material layer applied to both the front and back surfaces of the metal foil. electrode. The electrode according to claim 12 , wherein the active material layers formed on both front and back surfaces of the foil main body are in close contact with each other through the through hole. The electrode according to claim 12 or 13 , wherein the plurality of through holes are intermittently formed in the foil body at a pitch of 0.5 mm or more. The short side of the through hole is 1 to 500 [mu] m, the electrode according to any one of claims 12 to claim 14 in which the long side is characterized in that it is a 10～5000Myuemu. A battery comprising the electrode according to any one of claims 12 to 15 .