JP2013182810A - Collector, and lithium ion secondary battery using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a coating uniformly, by eliminating nonuniformity in the thickness of a coating applied to both sides of a collector.SOLUTION: The collector is provided with a plurality of through holes penetrating from one main surface to the other main surface of the collector. The through hole penetrates the collector substantially linearly, and one and the other openings of the through hole are located at positions substantially not overlapping each other, in the projection view from a direction perpendicular to one major surface of the collector.

Description

  The present invention relates to a current collector and a lithium ion secondary battery using the current collector.

  Batteries typified by lithium ion secondary batteries are basically a positive electrode, a negative electrode, a separator that insulates the positive electrode from the negative electrode, and an electrolyte solution that allows ions to move between the positive electrode and the negative electrode. It is configured. The positive electrode and the negative electrode are obtained by applying various active materials to the surface of a current collector made of a metal foil. For example, an active material containing lithium cobaltate or the like applied to a current collector made of an aluminum foil is used as the positive electrode, while an active material containing graphitized carbon or the like is made of copper foil as the negative electrode. What was apply | coated to the electrical power collector is used.

  Generally, when various active materials are applied to various metal foil surfaces such as aluminum foil and copper foil, there is a problem that the metal foil and the active material are difficult to be integrated and the active material is relatively easy to fall off. If the material falls off, a secondary battery having a desired capacity cannot be obtained. In addition, when the active material is dropped after the secondary battery is manufactured, there is a disadvantage that the charge / discharge capacity of the secondary battery is gradually reduced.

  For this reason, the foil in which the hole penetrated perpendicularly from the surface side to the back surface side of a current collector was devised (for example, patent documents 1 and 2).

  In patent document 2, it is further improved from the form of patent document 1, the through-hole which inclined in the electrical power collector is formed by the etching method, and the active material and binder apply | coated to the front and back of a electrical power collector And the technique which prevents dropping of an active material by making it easy to make it latch to this through-hole is disclosed (refer FIG.2,3,4).

  However, when the active material is applied to the holes (FIG. 1) vertically penetrated as described above and the current collectors (FIGS. 2 to 4) having the inclined holes, the paint is applied from the surface side of one current collector. Even if the coating is applied, the coating material wraps around the back surface side of the current collector, the coating material adheres to the back surface, and the coating film thickness becomes non-uniform.

Furthermore, in the case of a current collector having crater-like through holes as shown in FIG. 2, the hole diameters on the front surface and the back surface of the current collector are greatly different. Even if it applied, the problem that the thickness of the coating film differs on both surfaces arose. Referring to FIG. 2, since the hole diameter on the front surface side is wide, it is easy to fill with paint, but the hole diameter on the back surface side is narrow, and the intercept angle formed by the current collector surface and the inner wall surface of the through hole is an acute angle. Therefore, it is difficult for the paint to be filled in the holes. As described above, the difference in the hole diameters on the front and back surfaces of the current collector and the difference in ease of filling the coating amount tend to cause a difference in the coating thickness between the front surface and the back surface.
Further, in the case of the current collector in which the through holes are formed as shown in FIG. 4, the applied paint is unlikely to go around into the depressions inside the through holes, so that there is a problem that the whole hole is not easily filled with the paint.

  Thus, if a lithium ion secondary battery is produced with a difference in coating film thickness between the front surface side and the back surface side of the current collector, for example, the desired non-uniformity of the electrochemical reaction may cause There is a possibility that the cycle characteristics may not be obtained.

JP 2000-294250 A Japanese Patent Laid-Open No. 11-67217

  The present invention provides a current collector that eliminates the unevenness of the thickness of the applied coating film in a current collector having a through-hole and can form a coating film uniformly. An object of the present invention is to provide a highly reliable lithium ion secondary battery capable of obtaining battery characteristics.

  In order to achieve the above object, the current collector according to the present invention includes a plurality of through holes penetrating from one main surface of the current collector to the other main surface, and the through holes penetrate substantially linearly. The one opening and the other opening penetrating the current collector in a straight line are arranged at positions that do not substantially overlap each other when projected from the vertical direction of the one main surface of the current collector. ing.

  Thereby, even if a paint is applied on the current collector, it is possible to avoid going around to the back side through the through hole, and to uniformize the coating thickness on one side and the other side of the current collector. be able to.

  In the current collector according to the present invention, it is preferable that the opening area of the one opening and the opening area of the other opening are substantially equal.

  As a result, the amount of paint filled from the one opening and the amount of paint filled from the other opening are approximately the same, and the film thickness of the coating film formed on the current collector surface and the current collector back surface is more uniform. Can be formed.

  In the current collector according to the present invention, the opening shape of the one opening and the other opening of the current collector is preferably circular or polygonal.

  The lithium ion secondary battery according to the present invention includes a plurality of through holes penetrating from one main surface of the current collector to the other main surface, the through holes penetrating substantially linearly, and the current collector The one opening and the other opening penetrating in a straight line are arranged at positions that do not substantially overlap each other when projected from the vertical direction of the one main surface of the current collector. Is used for the negative electrode and / or the positive electrode.

  Thereby, the charge / discharge capacity acting on the electrode surface side and the back surface side can be accurately controlled, and a highly reliable lithium ion secondary battery can be provided.

  Here, in the present invention, the through-hole penetrating substantially linearly only needs to be substantially linear, and there may be some fluctuation of the inner wall of the through-hole caused by the etching process.

  In addition, the fact that one opening on one main surface of the through-hole in the present invention and the other opening on the other main surface do not substantially overlap each other is from the vertical direction of the one main surface of the current collector. When projected, it means that they do not substantially match, and if the difference in coating thickness between the one side and the other side of the current collector does not occur, the one opening A part of the other opening may overlap.

  Needless to say, “substantially equivalent” as described above is intended to allow a difference that does not impair the effects of the present invention as an allowable range.

  According to the present invention, it is possible to suppress the wraparound of the paint and to provide an electrode having a uniform thickness of the active material as compared with the case where a current collector having a conventional through hole is used. Can do. Further, by using the current collector of the present invention, a lithium ion secondary battery having highly reliable battery characteristics can be provided.

FIG. 1 is an explanatory view showing a current collector having a conventional through hole. (Patent Document 1) FIG. 2 is an explanatory view showing a current collector having a conventional through hole. (Patent Document 2) FIG. 3 is an explanatory view showing a current collector having a conventional through hole. (Patent Document 2) FIG. 4 is an explanatory view showing a current collector having a conventional through hole. (Patent Document 2) FIG. 5 is an example of an explanatory view showing a current collector having a through hole of the present invention. FIG. 6 is an explanatory view showing one process for producing a current collector (FIG. 5) having a through hole of the present invention by an etching method by photolithography. FIG. 7 is an explanatory view showing a current collector having through holes in a staggered pattern by an etching method using photolithography. FIG. 8 is an explanatory view showing one process for producing a current collector (FIG. 1) having a conventional through hole by an etching method using photolithography. It is explanatory drawing which showed the collector which has the conventional through-hole produced by the preparation method of FIG. FIG. 10 is an explanatory view showing a current collector having another through hole shape obtained by the present invention.

  In the current collector according to one embodiment of the present invention, an aluminum foil, an aluminum alloy foil, a copper foil, a copper alloy foil, or the like is preferably used as the metal foil constituting the perforated current collector. In the case of a lithium ion secondary battery, the current collector used for the positive electrode may be preferably an aluminum foil or an aluminum alloy foil, while the current collector used for the negative electrode is a copper foil or a copper alloy foil. good. In the present embodiment, a metal foil other than an aluminum foil or a copper foil can also be used as the current collector by appropriately selecting an etching solution in the photolithography process with respect to the material of the current collector.

  The thickness of the perforated current collector is usually about 8 to 30 μm. The current collector made of aluminum foil used for the lithium secondary battery is preferably about 15 to 25 μm, and the current collector made of copper foil is preferably 10 to 20 μm. The copper foil may be a rolled copper foil (a copper foil obtained by a rolling method) or an electrolytic copper foil (a copper foil obtained by an electrolytic method).

The shape of the through hole provided in the current collector is preferably a circular shape, but the shape is not particularly limited. The shape may be any shape such as a perfect circle or an ellipse, a polygon such as a triangle, a quadrangle, or a hexagon.
In particular, a circular shape or a hexagonal shape is preferable because a uniform coating film can be easily formed on the front and back surfaces of the current collector.

Further, the size of the through hole can be appropriately adjusted to an arbitrary size according to the type and size of the lithium ion secondary battery or the application.
Generally, assuming that the area of the through hole is the area of a virtual circle, the diameter of the virtual circle can be 0.1 to 3 mm.

  In particular, the size of the through hole is more preferably substantially the same opening area on the front and back surfaces of the current collector in the formation of a uniform coating film.

In addition, a large number of through holes are provided in the current collector. For example, the pitch between the through holes may be about 0.2 to 10 mm, and the density of the through holes may be about 1 to 2500 / cm ^2. . The pitch between the through holes means a distance connecting the opening of the through hole provided on the same plane of the current collector and the center of the opening of the through hole.

  Further, the through holes may be arranged on the current collector surface at an equal pitch, or may be arranged in a staggered pattern.

One of the features of the present invention is that the through hole is inclined at a specific intercept angle θ from one main surface of the metal foil to the other main surface. Here, the intercept angle is a cross section from a direction perpendicular to one main surface of the metal foil, that is, a line on the front or back surface of the metal foil that appears in the vertical cross section of the through hole, and an inner wall surface in the inclined through hole. This is the angle formed with the line.
This can be understood more clearly with reference to FIG. The front and back surfaces of the metal foil are not used in a strict sense, but when one main surface is used as the front surface, the other main surface is used as the back surface. Only.

FIG. 5 will be described in detail below.
FIG. 5 shows a cross-sectional form of the current collector of the present invention.
The intercept angle θ1 formed by the surface 1 of the current collector and the inner wall surface 3 of the through hole is 10 ° to 80 °, and the intercept angle formed by the back surface 2 of the current collector and the inner wall surface 3 of the through hole θ3 is 100 ° to 170 °, and the intercept angle θ2 formed by the surface 1 of the current collector and the inner wall surface 4 of the through hole is 100 ° to 170 °. A through hole having an intercept angle θ4 of 10 ° to 80 ° formed by the inner wall surface 4 of the hole is provided.
The intercept angles of the above θ1, θ2, θ3, and θ4 can be appropriately selected depending on the thickness of the current collector and the hole diameter of the through hole, and the opening hole on the front surface side and the opening hole on the back surface side of the current collector are Adjustments are made so that they are not vertically opposed, that is, arranged in positions that do not overlap each other. In addition, the said facing is a state where the holes on the front surface side and the holes on the back surface side are perpendicularly opposed as shown in FIGS. 1 to 4 and the opening diameters on the front surface side and the back surface side overlap each other. Means.

  As described above, when the paint is applied from the current collector surface 1 side to the current collector having the inclined through hole as shown in FIG. 5, the paint hits the wall surface 4 in the through hole. Prevents wrapping around the back of the body. Further, when the paint is applied from the current collector back surface 2 side, the paint is also prevented from flowing around the surface of the current collector.

  The current collector having the through holes as described above can be obtained by an arbitrary method such as an etching method by photolithography or a punching method.

The current collector shown in FIG. 5 has a perforated resist film having a large number of through holes bonded to the surface of the non-porous metal foil, and a perforated resist film is bonded to the back surface of the non-porous metal foil. By etching the three-layer laminate, a large number of through holes corresponding to the holes of the perforated resist film can be formed in the non-porous metal foil.
As the non-porous metal foil, any metal foil such as an aluminum foil or a copper foil having no holes can be used.

A perforated resist film having a large number of inclined through holes is bonded to the surface of such a non-porous metal foil. The perforated resist film is formed by applying a resist solution made of an ultraviolet curable photosensitive resin to the surface of the non-porous metal foil, forming a resist layer, and then passing a positive film (film with a positive pattern) through the resist layer. By irradiating other parts with ultraviolet light without irradiating only the part to be perforated with ultraviolet light, curing the other part, and washing and removing the photosensitive resin in the uncured part with a developer. Can be easily obtained.
In the above ultraviolet irradiation, an inclined perforated resist film can be obtained by providing a specific inclination angle with a non-porous metal foil on which a resist layer passed through a positive film is formed with respect to the ultraviolet irradiation light.

Conversely, a resist solution made of an ultraviolet-decomposable (collapse-type) photosensitive resin is applied to form a resist layer, and then a negative film (a glass plate with a negative pattern) is passed through the resist layer. It can also be obtained by irradiating only the part to be opened with ultraviolet rays, and then washing and removing the decomposed photosensitive resin in the part irradiated with the ultraviolet rays.
On the other hand, a non-porous resist film is bonded to the back surface of the non-porous metal foil. The non-porous resist film can be easily obtained by irradiating the entire surface with ultraviolet rays after forming a resist layer when a resist solution made of an ultraviolet curable photosensitive resin is used. Further, when a resist solution made of an ultraviolet-decomposable photosensitive resin is used, it is allowed to leave the resist layer so as not to irradiate ultraviolet rays as much as possible.

  Etching is then performed on the three-layer laminate in which the inclined perforated resist film, non-porous metal foil, and non-porous resist film are laminated in this order. Etching is performed using an etching solution (for example, ferric chloride-nitric acid aqueous solution) that dissolves the nonporous metal foil but does not dissolve the resist film. Etching is generally performed by spraying an etching solution from a spray nozzle toward the inclined perforated resist film of the three-layer laminate. Moreover, it can also carry out by immersing a three-layer laminated body in an etching liquid. By such a method, the etching solution enters from the inclined holes of the resist film, dissolves the non-porous metal foil, and a perforated current collector having a large number of inclined through holes as shown in FIG. 5 is obtained.

  Furthermore, as another form of the back surface of the non-porous metal foil, an inclined perforated resist film may be bonded. The inclined perforated resist film on the back surface side may be formed by a method similar to that of the perforated resist film inclined on the front surface side. That is, it is in the form of a three-layer structure of an inclined perforated resist film-non-porous metal foil-an inclined perforated resist film. In the case of such a form, both surfaces of the non-porous metal foil can be simultaneously etched with a ferric chloride-nitric acid aqueous solution. However, in the present embodiment, it is necessary to adjust so that the inclined hole provided in the resist film on the back surface side is connected substantially linearly to the inclined hole provided in the resist film on the front surface side of the current collector. Yes, that is, when the non-porous metal foil is etched and dissolved with a ferric chloride-hydrochloric acid aqueous solution, the inclined hole formed from the front side of the metal foil and the inclined hole formed from the back side form one straight line at the end of etching. It is necessary to form a through hole. Note that the resist film described above is used to mean a resist film for etching.

  On the other hand, it is possible to produce a current collector in which inclined through holes are formed by directly punching the non-porous metal foil with a punching jig in a state where the non-porous metal foil is provided with a specific inclination. As other punching methods, a current collector in which inclined through holes are formed can be obtained by a mechanical punching method, a drill method, a laser irradiation method, or the like.

  Based on the above embodiment, the present invention will be further described in the following examples. In particular, in the present invention, preparation of a perforated current collector by an etching method using photolithography will be described. However, the following examples do not limit the present invention.

Example 1
A non-porous electrolytic copper foil having a width of 20 cm, a length of 50 cm, and a thickness of 20 μm was prepared. A resist solution (OFPR-800, manufactured by Tokyo Ohka Kogyo Co., Ltd.) was uniformly applied to both surfaces of this electrolytic copper foil, and dried at 110 ° C. for 5 minutes to form a resist layer.

  On the other hand, a negative film was prepared in which circles having a diameter of 0.2 mm were baked at a pitch of 3 mm in the width direction and at a pitch of 3 mm in the length direction. The negative film had a width of 20 cm and a length of 50 cm so as to match the size of the electrolytic copper foil. The thickness of the negative film was 0.2 mm.

This negative film is laminated on a resist layer bonded to the surface of the non-porous electrolytic copper foil, and irradiated with 300 mJ / cm ² of ultraviolet light from an ultraviolet exposure device provided at a certain distance from the negative film. A latent image was formed on the layer. At this time, ultraviolet rays were irradiated so that the acute angle of the surface of the non-porous electrolytic copper foil in which the negative film was laminated on the resist layer and the slice formed by the ultraviolet irradiation light became 80 °. Then, it was developed with an NMD-3 developer manufactured by Tokyo Ohka Kogyo Co., Ltd. for at least 30 seconds, lightly washed with water, and then dried at 110 ° C. for 5 minutes.

  As a result, as shown in FIG. 6, in the resist layer bonded to the surface of the non-porous electrolytic copper foil, circular through holes having a diameter of about 0.2 mm are arranged at a pitch of 3 mm in the width direction and in the length direction. The through-holes were formed at a pitch of 3 mm, and the acute angle (θ1) of the section formed by the resist layer surface and the inner walls of the through-holes was approximately 80 °. In addition, the resist layer bonded to the back surface of the non-porous electrolytic copper foil was not irradiated with ultraviolet rays, and was used as the original non-porous resist layer. As described above, a three-layer laminate was obtained in which a perforated resist layer, a nonporous electrolytic copper foil, and a nonporous resist layer were laminated in this order.

Then, the etching solution is applied in the same direction as the direction in which the holes of the inclined through holes extend so that the through holes formed on the perforated resist layer side of the three-layer laminate are irradiated vertically. Jetted. That is, an etching solution composed of a mixed aqueous solution of 2.2 mol / dm ³ FeCl ₃ and 1.0 mol / cm ³ HCl (liquid temperature of about 50 ° C.) is applied at least at a pressure of 0.15 MPa from six nozzles. Etching was performed by spraying toward the perforated resist layer for 15 seconds. After this, it was immediately washed with water and dried at 110 ° C. for 5 minutes.

  Subsequently, in order to remove each resist layer of a three-layer laminated body, it immersed in acetone and dried for 5 minutes at 110 degreeC. As a result, a copper foil in which through holes having a diameter (diameter on the copper foil surface side) of about 0.2 mm were provided at a pitch of 3 mm in the width direction and at a pitch of 3 mm in the length direction was obtained. This copper foil was cut into a width of 10 cm and a length of 50 cm to obtain a perforated current collector.

  When this current collector was cut and the cross-sectional shape of the through hole appearing on the current collector cross section was observed with a microscope, it was an inclined through hole as shown in FIG. 5, and θ1 was about 70 ° and θ2 Was about 120 °, θ3 was about 110 °, and θ4 was about 60 °.

  In addition, since the negative film formed in a staggered pattern in Example 1 was used, the through hole of the obtained apertured collector was viewed from a direction perpendicular to one main surface of the collector, A perforated current collector arranged in a staggered pattern as shown in FIG. 7 was obtained.

  When a paint having a viscosity of 35,500 mPa · s, which is a mixture of an active material made of silicon and a polyimide binder, was applied to the surface of the perforated current collector, no wraparound of the paint was confirmed from the through hole to the back surface. . Furthermore, as a result of applying the same amount of the coating material on the back surface side, a coating film having a substantially uniform coating film thickness on the back surface side was formed. Here, when the thickness of the coating film on the front surface side was relatively 100, the coating film thickness on the back surface side was also 100.

  Further, the above electrode was used as a negative electrode of a lithium ion secondary battery, and a battery cell was prepared using a positive electrode, a separator, and an electrolytic solution, and the cycle characteristics at a potential of 2.5 to 4.2 V were evaluated. Showed 90%.

  For reference, the current collector manufactured in the same manner as in Example 1 except that the shape of the opening of the through hole in Example 1 was hexagonal, the same result as in Example 1 was obtained.

(Comparative Example 1)
A non-porous electrolytic copper foil having a width of 20 cm, a length of 50 cm, and a thickness of 20 μm was prepared. A resist solution (OFPR-800, manufactured by Tokyo Ohka Kogyo Co., Ltd.) was uniformly applied to both surfaces of this electrolytic copper foil, and dried at 110 ° C. for 5 minutes to form a resist layer.

  On the other hand, a negative film was prepared in which circles having a diameter of 0.2 mm were baked at a pitch of 3 mm in the width direction and at a pitch of 3 mm in the length direction. The negative film had a width of 20 cm and a length of 50 cm so as to match the size of the electrolytic copper foil. The thickness of the negative film was 0.2 mm.

This negative film is laminated on a resist layer bonded to the surface of the non-porous electrolytic copper foil, and irradiated with 300 mJ / cm ² of ultraviolet light from an ultraviolet exposure device provided at a certain distance from the negative film. A latent image was formed on the layer. At this time, the surface of the non-porous electrolytic copper foil in which the negative film was laminated on the resist layer and the section formed by the ultraviolet irradiation light were irradiated with ultraviolet rays so that the acute angle was 90 °. Then, it was developed with an NMD-3 developer manufactured by Tokyo Ohka Kogyo Co., Ltd. for at least 30 seconds, lightly washed with water, and then dried at 110 ° C. for 5 minutes.

  As a result, as shown in FIG. 8, the resist layer bonded to the surface of the non-porous electrolytic copper foil has through holes having a diameter of approximately 0.2 mm at a pitch of 3 mm in the width direction and a pitch of 3 mm in the length direction. The through-hole was formed, and the angle (θ1) formed by the resist layer surface and the inner wall of the through-hole formed approximately 90 °. In addition, the resist layer bonded to the back surface of the non-porous electrolytic copper foil was not irradiated with ultraviolet rays, and was used as the original non-porous resist layer. As described above, a three-layer laminate was obtained in which a perforated resist layer, a nonporous electrolytic copper foil, and a nonporous resist layer were laminated in this order.

And the etching liquid was sprayed so that it might irradiate perpendicularly with respect to the through-hole formed in the perforated resist layer side of this three-layer laminated body. That is, an etching solution composed of a mixed aqueous solution of 2.2 mol / dm ³ FeCl ₃ , 1.0 mol / cm ³ and HCl (liquid temperature of about 50 ° C.) is applied at least at a pressure of 0.15 MPa from six nozzles. Etching was performed by spraying toward the perforated resist layer for 15 seconds. After this, it was immediately washed with water and dried at 110 ° C. for 5 minutes.

  Subsequently, in order to remove each resist layer of a three-layer laminated body, it immersed in acetone and dried for 5 minutes at 110 degreeC. As a result, a copper foil (FIG. 9) in which through-holes having a diameter (diameter on the copper foil surface side) of about 0.2 mm were provided at a pitch of 3 mm in the width direction and a pitch of 3 mm in the length direction was obtained. . This copper foil was cut into a width of 10 cm and a length of 50 cm to obtain a perforated current collector.

  When this current collector was cut and the cross-sectional shape of the through hole appearing in the current collector cross section was observed with a microscope, it was an inclined through hole as shown in FIG. 9, and θ1 was about 90 ° and θ2 Was about 90 °, θ3 was about 90 °, and θ4 was about 90 °.

When the coating material produced in Example 1 was applied to the surface of the perforated current collector, the coating material wraps around from the through hole on the back surface side. Furthermore, as a result of applying the same amount of coating material on the back surface side, the coating film thickness on the back surface side was larger than the thickness of the coating film formed on the front surface side.
Here, when the thickness of the coating film on the front surface side was relatively 100, the coating film thickness on the back surface side was 120. The reason why the thickness of the coating film on the back surface side is increased is considered to be that the coating applied on the front surface side wraps around the back surface side through the through hole.

  Further, the above electrode was used as a negative electrode of a lithium ion secondary battery, and a battery cell was prepared using a positive electrode, a separator, and an electrolytic solution, and the cycle characteristics at a potential of 2.5 to 4.2 V were evaluated. Was 82%. Therefore, it was clear that the negative electrode produced in Comparative Example 1 was not more suitable as the electrode of the lithium ion secondary battery than the negative electrode produced in Example 1 as the negative electrode of the lithium ion secondary battery. .

  Table 1 summarizes the results.

  The perforated current collector produced in the present invention is not limited to the above production method, and is not limited to this as long as through holes are formed by a suitable method.

  In addition, among the variations, in the cross section of the current collector, as shown in FIG. 10, a shape in which two adjacent inclined through-holes intersect with each other, as well as the current collector of FIG. I know. Although not clearly shown in FIG. 10, two inclined linear through holes are formed so as to intersect with each other, so that the two through holes have a joining portion inside the current collector. Moreover, you may form mutually shifted | deviated so that the junction part may be eliminated.

  The through hole as shown in FIG. 10 can be obtained by performing etching by photolithography according to the present invention a plurality of times. Various variations are conceivable as described above, and the present invention is not limited to the shapes described in the present embodiment. Needless to say, as shown in FIG. 5, the through-hole shape does not need to be a parallelogram, and may be deformed inside if the effects of the present invention are not impaired.

  By using the perforated current collector provided in the present invention, a current collector that can improve the non-uniformity of the applied coating thickness is provided, and as a result, a highly reliable lithium ion secondary battery is provided. Can be provided.

DESCRIPTION OF SYMBOLS 1 Front surface of current collector 2 Back surface of current collector 3 Inner wall surface of inclined through hole 4 Inner wall surface of inclined through hole

Claims (4)

A plurality of through holes penetrating from one main surface of the current collector to the other main surface are provided,
The through hole penetrates substantially linearly,
One opening and the other opening penetrating the current collector linearly,
The current collector is disposed at a position that does not substantially overlap each other when projected from the vertical direction of the one main surface of the current collector.   The current collector according to claim 1, wherein an opening area of the one opening of the current collector is substantially equal to an opening area of the other opening.   The current collector according to claim 1 or 2, wherein an opening shape of the one opening and the other opening of the current collector is a circular shape or a polygonal shape.   The lithium ion secondary battery produced using the electrical power collector of Claims 1-3 for a negative electrode and / or a positive electrode.

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