JP7015977B2 - Power storage device - Google Patents

Description

The present invention relates to a power storage device.

In power storage devices such as lithium ion batteries, lithium ion capacitors, electric double layer capacitors, and all-solid-state batteries, metal foil is used for the current collector. For example, in a lithium ion battery, an aluminum foil is mainly used as a positive electrode current collector and a copper foil is mainly used as a negative electrode current collector.

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 predoping 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, a plurality of through holes are formed in the metal foil by passing the metal foil between the roll having an uneven surface and the smooth roll, and the metal foil and the active material adhere to each other. It has been proposed to improve sex. Patent Document 3 discloses a method of forming a large number of through holes in a metal foil by an etching process.

Japanese Patent No. 4074689 Japanese Patent No. 583080 Japanese Unexamined Patent Publication No. 2011-216364

Patent Document 2 describes that when a metal foil is passed between a roll having an uneven surface and a smooth roll to perform a hole drilling process, fine metal pieces are generated during the hole drilling process. Has been done. If a metal piece of a certain size gets mixed in the battery, a short circuit may occur inside. Although some documents have reported a method of removing the generated metal pieces later, an internal short circuit is a fatal phenomenon in terms of battery safety, and it is desirable to suppress the generation itself.

The method described in Patent Document 3 has a low risk of generating the above-mentioned metal pieces, but is more productive than the physical drilling method because it is a manufacturing method such as forming a resist film, etching, and removing the resist film. It is extremely low, and there is a concern that the manufacturing cost as a current collector will be extremely high.

An object of the present invention is to provide a power storage device capable of manufacturing an electrode without causing troubles such as breakage and deformation.

The first aspect of the present invention includes a foil-shaped current collector and a current terminal connected to one side of the current collector, and a plurality of slit-shaped through holes are formed in the current collector. The ratio (L / D) of the through hole to the length (L) in the length direction and the distance (D) between the through holes adjacent to each other in the length direction of the through hole is 1.0 or less. It is characterized by that.

A second aspect of the present invention is an invention based on the first aspect, in which the first through-hole row in which the through-holes are arranged in a row in the same length direction of the through-holes and the first through-holes are aligned. It has a second through-hole row having a smaller ratio (L / D) than the row, and the first through-hole row and the second through-hole row are alternately arranged in the width direction of the through-hole. It is characterized by.

The third aspect of the present invention is the invention based on the first or second aspect, and is characterized in that the interval D is 0.5 mm or more.

A fourth aspect of the present invention is an invention based on any one of the first to third aspects, wherein the through hole has a length W in the width direction of 1 to 500 μm and a length L in the length direction. Is 10 to 5000 μm.

A fifth aspect of the present invention is an invention based on any one of the first to fourth aspects, wherein the through hole is a pair of long sides parallel to the length direction of the through hole and the pair. It is characterized by having short sides formed in a constricted shape on both ends of the long side of the.

According to the first aspect of the present invention, the through hole has a ratio (L / D) of the length L in the length direction and the distance D in the length direction of the through hole to be 1.0 or less. Since it is formed, the strength required for unwinding and winding is maintained, so that the electrode can be manufactured without causing problems such as breakage and deformation.

According to the second aspect of the present invention, since it has through holes, the adhesiveness of the mixture layer can be obtained, the increase in resistance can be suppressed as a whole, and by including the second through hole row, it is possible to obtain more. The strength can be surely improved.

According to the third and fourth viewpoints of the present invention, it is possible to withstand the tension applied at the time of unwinding and winding at the time of manufacturing a secondary battery.

According to the fifth aspect of the present invention, since the through hole can be formed without generating an unnecessary metal piece, it is possible to obtain a current collector in which the metal piece does not adhere.

It is a schematic diagram which shows the structure of the lithium ion secondary battery which concerns on this embodiment. It is a top view which shows the current collector of the lithium ion secondary battery which concerns on this embodiment, FIG. 2A is a positive electrode current collector, and FIG. 2B is a negative electrode current collector. It is a partially enlarged plan view of the current collector which concerns on this embodiment. It is an enlarged plan view of the through hole which concerns on this embodiment. It is an enlarged perspective view seen from the surface side of the through hole which concerns on this embodiment. It is an enlarged perspective view seen from the back surface side of the through hole which concerns on this embodiment. It is an end view for demonstrating the state which forms the through hole which concerns on this embodiment. It is a perspective view which shows the method of forming the through hole which concerns on this embodiment. It is a schematic diagram which shows the manufacturing apparatus which forms the through hole which concerns on this embodiment. It is a top view of the metal foil used for manufacturing the current collector which concerns on this embodiment. It is a schematic diagram which shows the modification of the manufacturing apparatus which forms the through hole which concerns on this embodiment. It is a top view which shows the modification (1) of the metal foil used for manufacturing the current collector which concerns on this embodiment. It is a top view which shows the modification of the current collector of the lithium ion secondary battery which concerns on this embodiment, FIG. 13A is a positive electrode current collector, and FIG. 13B is a negative electrode current collector. It is a top view which shows the modification (2) of the metal foil used for manufacturing the current collector which concerns on this embodiment.

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

1. 1. Overall Configuration As shown in FIG. 1, the lithium ion secondary battery 10 as a power storage device includes a positive electrode 12, a negative electrode 14, a separator 16, and a case 17 for accommodating them. In the lithium ion secondary battery 10 shown in this figure, five positive electrodes 12 and five negative electrodes 14 are alternately stacked with a separator 16 interposed therebetween. The positive electrode 12, the negative electrode 14, and the separator 16 are prepared in a non-aqueous solvent containing, for example, ethylene carbonate (EC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), dimethyl carbonate (DMC), and LiPF ₆ , LiBF ₄ , and LiClO. It is immersed in an electrolytic solution (not shown) mixed with a lithium salt such as ₄ .

The positive electrode 12 has a foil-shaped positive electrode current collector 18 and a positive electrode mixture layer 20 provided on one side or both side surfaces of the positive electrode current collector 18. For the positive electrode current collector 18, for example, an aluminum or aluminum alloy foil can be used. The positive electrode mixture layer 20 contains an active material such as LiCoO ₂ (LCO) and a binder such as polyvinylidene fluoride or polyamide-imide.

The negative electrode 14 has a foil-shaped negative electrode current collector 22 and a negative electrode mixture layer 24 provided on one side or both side surfaces of the negative electrode current collector 22. For the negative electrode current collector 22, for example, a copper or copper alloy foil can be used. The negative electrode mixture layer 24 contains an active material such as natural graphite and a binder such as styrene, butadiene, and rubber.

The positive electrode mixture layer 20 and the negative electrode mixture layer 24 may further contain a conductive auxiliary agent such as acetylene black, ketjen black, and carbon nanotube, and a thickener such as carboxymethyl cellulose.

The plurality of positive electrodes 12 are bundled at the terminal connection portion 19, arranged on one side surface of the positive electrode current terminal 26, and fixed by welding. For welding, for example, ultrasonic welding can be used. When welding, a backing plate 30 is placed on the surface of the bundled terminal connection portion 19, ultrasonic waves are irradiated from the other side surface of the positive electrode current terminal 26, and the terminal connection portion 19 bundled together with the backing plate 30 is subjected to a positive electrode current. It is fixed to one side surface of the terminal 26. As the backing plate 30, the same aluminum or aluminum alloy plate as the positive electrode current collector 18 is used.

The plurality of negative electrodes 14 are also bundled at the terminal connection portion 23, and are fixed to one side surface of the negative electrode current terminal 28 together with the backing plate 32 by welding in the same manner as the positive electrode 12. As the backing plate 32, a nickel plate or a nickel-plated copper plate is used.

The welding in the positive electrode 12 and the negative electrode 14 is not limited to ultrasonic welding, and for example, resistance welding and laser welding can be used.

As shown in FIG. 2, the positive electrode current collector 18 has a foil body 18A including a mixture forming region 36. A terminal connection portion 19 is integrally formed on the foil body 18A. The foil body 18A has a rectangular shape, and the central portion excluding the peripheral edge is the composite material forming region 36. The positive electrode mixture layer 20 is provided in the mixture forming region 36. The terminal connection portion 19 is formed on one side of the foil body 18A. In the case of this figure, the terminal connection portion 19 is provided on the left side of the upper side of the foil main body 18A and protrudes from the upper side. The positive electrode current collector 18 is formed with a large number of slit-shaped through holes 34 penetrating in the thickness direction.

Like the positive electrode current collector 18, the negative electrode current collector 22 has a foil body 22A including a composite material forming region 38 and a terminal connection portion 23, and a large number of slit-shaped through holes 34 are formed. The negative electrode mixture layer 24 is provided in the mixture forming region 38. The terminal connection portion 23 is provided on the right side of the upper side of the foil main body 22A, which is on the opposite side of the positive electrode current collector 18, and protrudes from the upper side.

In the present specification, when the positive electrode current collector 18 and the negative electrode current collector 22 are not distinguished, they are collectively referred to as a current collector. The orientation of the through hole 34 is not particularly limited, but in the case of this figure, the length direction of the through hole 34 is formed so as to be parallel to the one side of the foil bodies 18A and 22A.

As shown in FIG. 3, the through holes 34 are adjacent to each other in the length direction. The through holes 34 are arranged in a row with an interval D in the length direction of the through holes 34, and are arranged with an interval T in the width direction. The distance D between the through holes in the length direction is preferably 0.5 mm or more, for example. If it is less than 0.5 mm, there is a problem that the through hole 34 and the through hole 34 are connected even if the hole is opened with a rotary blade having a small diameter. In the case of this figure, the through holes 34 adjacent to each other in the width direction are arranged in a state where the positions of the through holes 34 in the length direction are aligned. The through hole 34 is formed so that the ratio (L / D) of the length L in the length direction and the distance D in the length direction is 1.0 or less. If the ratio (L / D) exceeds 1.0, the interval D is too narrow, and the current collector may be deformed or broken in the manufacturing process. Since the through hole 34 has a horizontally long slit shape, if the interval D is too narrow, the metal existing between the through holes 34 will break with a small force. Further, once broken, it easily propagates to the next through hole 34, which in turn causes a problem that a long linear hole is formed. In the case of this figure, the interval D is constant, but may change periodically or randomly. The ratio (L / D) is preferably 0.8 or less, more preferably 0.5 or less. The ratio (L / D) is preferably 0.05 or more. When the ratio (L / D) is less than 0.05, the length L of the through hole 34 is too short, so that it becomes difficult to obtain effects such as binding property, liquid permeability, and gas permeability.

The ratio (L / D) depends on the size of the electric capacity of the power storage device to be applied. For example, in the case of consumer power storage devices such as mobile phones and smartphones, which require a small amount of electric capacity, the length of the electrodes used is short, so the number of times the electrodes are wound when stacking batteries is generally 7 to 8 times. And few. Therefore, since the tensile load applied to the electrode plate including the current collector is small, the ratio (L / D) can be relatively large, that is, the interval D with respect to the length L can be relatively narrowed.

On the other hand, in the case of an in-vehicle power storage device that requires a large electric capacity, the length of the electrodes used is long, so that the number of times the electrodes are wound when stacking batteries is as many as several tens. Therefore, since a larger tensile load is applied to the electrode plate including the current collector, it is necessary to reduce the ratio (L / D), that is, widen the interval D with respect to the length L to increase the strength of the current collector foil.

As described above, by appropriately adjusting the ratio (L / D) for preventing the current collector foil from being damaged depending on the size of the power storage device, it becomes possible to manufacture the power storage device without defects at the manufacturing stage.

The spacing T in the width direction can be selected, for example, in the range of 1 mm to 20 mm. If the interval T is too narrow, the mechanical strength is lowered, and therefore, if tension is applied in the length direction of the through hole 34 in the manufacturing process, the current collector may be deformed. On the contrary, when the interval T is too large, the number of through holes 34 per unit width is reduced, and improvement in binding property at the through holes 34 portion cannot be expected. Due to the decrease in the through holes 34, there is a problem that the liquid permeability and the gas permeability between the positive electrode mixture layers 20 and the negative electrode mixture layers 24 on both side surfaces are lowered.

As shown in FIG. 4, the through hole 34 has a pair of long side portions 34B parallel to the length direction of the through hole 34 and a long side portion 34B having a constricted tip on both ends in the length direction of the through hole 34. It has an opening 34A including a short side portion 34C integrally formed with the above. The distance between the long side portions 34B is defined as the length (slit width) W in the width direction of the through hole 34, and the distance between the short side portions 34C is defined as the length L in the length direction of the through hole 34. The through hole 34 preferably has an aspect ratio (L / W) defined by a length L and a length W of 10 or more. When the aspect ratio (L / W) is less than 10, the through hole 34 has a shape close to a square, and the metal foil is torn off when the through hole is formed, which will be described later, and fine metal pieces are generated, which is not preferable. The higher the aspect ratio (L / W) of the through hole 34, the more the effect of reducing the generation of metal pieces can be improved. The upper limit of the aspect ratio (L / W) is not particularly limited, but is more preferably about 200 from the viewpoint of ease of processing and handling.

The length L of the through hole 34 is preferably in the range of 10 μm or more and 5000 μm or less, and the length W is preferably in the range of 1 μm or more and 500 μm or less. In the above range, the length L is more preferably in the range of 500 μm or more and 3000 μm or less, and the length W is more preferably in the range of 5 μm or more and 100 μm or less.

The thickness of the current collector is preferably in the range of 1 μm to 40 μm. If the current collector is thinner than 1 μm, the strength will be insufficient and there is a risk of deformation during winding and unwinding. If the current collector is thicker than 40 μm, the merit as a current collector will be reduced.

As shown in FIGS. 5 and 6, the through hole 34 is formed with a burr 35 protruding from the back surface side of the current collector on substantially the entire circumference of the opening 34A. The burr 35 is composed of a long side burr portion 35A protruding from the long side portion 34B of the opening 34A and a short side burr portion 35B protruding from the short side portion 34C, and has two long side burr portions 35A and two short sides. The burr portion 35B surrounds almost the entire circumference of the periphery of the opening 34A on the back surface side of the current collector.

As shown in FIG. 7, these burrs 35 are formed by partially plastically deforming a current collector penetrating the cutting edge portion 40G in the thickness direction.

Therefore, the height (length) H of the long side burr portion 35A is formed to be larger than 1/2 of the length W of the slit of the through hole. The height (length) H of the long side burr portion 35A and the height (length) H of the short side burr portion 35B are almost the same. The height H of the long side burr portion 35A is formed to be larger than 1/2 of the length W of the through hole 34 because the cutting edge portion 40G of the tool 40 has a part of the foil body 18A (22A) having a thickness thereof. This is the result of the metal material constituting the foil body 18A (22A) being stretched by plastic deformation when penetrating in the direction.

2. 2. Manufacturing method Next, a method of forming a current collector will be described. The current collector can be formed by forming a through hole 34 in the metal foil and cutting the metal foil into a predetermined shape. The metal foil is an aluminum or aluminum alloy foil when forming the positive electrode current collector 18, and a copper or copper alloy foil when forming the negative electrode current collector 22.

The through hole 34 can be formed by using the tool 40 shown in FIG. The tool 40 has a disk-shaped rotary blade 40D rotatably provided on a part of the support shaft 40A by the shaft portion 40B. A plurality of convex cutting blades 40F are alternately formed at regular intervals on the outer peripheral edge portion of the rotary blade 40D via a plurality of concave portions 40E in the circumferential direction, and the cutting edge portion 40G is formed at the tip portion of the cutting blade 40F. A rotary type clearance blade is formed.

The rotary blade 40D of this tool 40 is pressed at a right angle to the metal foil 41, and the rotary blade 40D is rotationally moved along the length direction of the metal foil 41 while being processed so as to penetrate the metal foil 41 at each cutting edge portion 40G. As a result, a plurality of through holes 34 can be intermittently formed in a row in the metal foil 41. Prior to this processing, it is preferable to arrange a receiving material such as a rubber sheet on the back surface side of the metal foil 41 and use it as a cushioning material when the cutting edge portion 40G penetrates the metal foil 41.

By using the tool 40 provided with the rotary blade 40D in this way, it is possible to form the through hole 34 in the metal foil 41 while forming the burr 35 using the cutting edge portion 40G. A metal foil 41 having a large number of through holes 34 can be easily manufactured. By forming a through hole 34 having an aspect ratio of 10 or more in the metal foil 41 by penetrating using the cutting edge portion 40G, the material of the metal foil 41 is stretched by the cutting edge portion 40G and plastically deformed to generate the through hole 34. Since the burrs 35 are formed, the through holes 34 can be formed without individually generating foreign matters such as fine metal pieces. Therefore, the metal foil 41 having no foreign matter such as fine metal pieces is suitable for the current collector of the lithium ion secondary battery 10, and can provide a high-quality current collector without a risk of internal short circuit or the like. ..

FIG. 9 shows a manufacturing apparatus 42 suitable for continuously forming a plurality of rows of through holes 34 in a long strip-shaped metal foil 41.

The manufacturing apparatus 42 has a winding reel 43 capable of unwinding the strip-shaped metal foil 41 and a take-up reel 44 capable of winding the metal foil 41, and is pressed between the unwinding reel 43 and the take-up reel 44. A roll 45 and a rotary blade 46 are provided, and adjustment reels 47 are provided before and after them.

The rotary blade 46 has a configuration in which a plurality of blade edge portions 46a are provided on the outer peripheral portion and rotary blades 46c provided via recesses 46b are laminated in a required number in the thickness direction. The number of laminated rotary blades 46c corresponds to the number of rows of through holes 34 formed in the width direction of the metal foil 41.

The pressing roll 45 has an elastic body layer on the outer peripheral portion, or is a roll made entirely of an elastic body, and the tip of the cutting edge portion 46a is formed when the strip-shaped metal foil 41 is pierced by the cutting edge portion 46a of the rotary blade 46. It is a cushion roll for elastically receiving.

The strip-shaped metal foil 41 wound around the unwinding reel 43 is unwound, passed between the rotary blade 46 and the pressing roll 45 via one adjusting reel 47, and wound through the other adjusting reel 47. Wind up on reel 44. By this operation, a plurality of rows of through holes 34 can be intermittently and sequentially simultaneously formed in the metal foil 41 that has passed between the rotary blade 46 and the pressing roll 45 by the plurality of cutting edge portions 46a of the rotary blade 46.

By forming the through holes 34 in the metal foil 41 in a configuration in which a plurality of rotary blades 46 are arranged in parallel, it is possible to form a plurality of through holes 34 in a state of being accurately aligned at predetermined intervals in the width direction of the metal foil 41. By using the manufacturing apparatus 42 shown in this figure, as shown in FIG. 10, the through holes 34 are uniformly and accurately arranged in a strip shape along the length direction of the metal foil 41. The metal foil 41 can be formed. By cutting out the metal foil 41 shown in this figure into a predetermined shape, a current collector according to the present embodiment can be obtained.

3. 3. Actions and effects When the positive electrode mixture layer 20 or the negative electrode mixture layer 24 is provided on both side surfaces of the current collector, the positive electrode mixture layers 20 or the negative electrode mixture layers 24 on both side surfaces pass through the through hole 34. In close contact. Therefore, the positive electrode 12 or the negative electrode 14 improves the adhesion of the positive electrode mixture layer 20 or the negative electrode mixture layer 24 to the current collector.

When the mixed material slurry is applied to the metal foil 41 to form the positive electrode mixed material layer 20 or the negative electrode mixed material layer 24, tension is applied to the metal foil 41 in the length direction. The length direction of the through hole 34 is along the length direction of the metal foil 41, and the ratio (L / D) of the length L in the length direction and the distance D in the length direction is 1.0 or less. Since it is formed so as to be, the strength required for unwinding and winding is maintained, so that the mixed material slurry can be applied without causing problems such as breakage or deformation of the metal foil 41.

The through holes 34 of the foil bodies 18A and 22A have an aspect ratio (L / W) of 10 or more, and the through holes 34 are formed by the tool 40 or the manufacturing apparatus 42 described above. It is possible to obtain a secondary battery in which unnecessary conductive foreign matter such as a metal piece is not attached and there is no risk of internal short circuit due to the conductive foreign matter in the current collector.

The current collector is provided with a through hole 34 in which the ratio (L / D) of the length L in the length direction to the distance D in the length direction is 1.0 or less and the aspect ratio (L / W) is 10 or more. As a result, it is possible to prevent breakage or deformation of the metal foil 41 and an internal short circuit caused by a conductive foreign substance in the current collector, and it is possible to reduce the defect rate of the secondary battery.

The length L of the through hole 34 is in the range of 10 μm to 5000 μm, and the length W is in the range of 1 μm to 500 μm. Since the thickness is 1 μm to 40 μm and the through holes 34 are formed in the metal foil 41 at intervals D of 0.5 mm or more, it is practical to withstand the application of tension during unwinding and winding during secondary battery manufacturing. Has strength.

Since a plurality of through holes 34 are formed in the current collector, the electrolytic solution easily permeates from the outer peripheral portion to the inside through the through holes 34, and the resistance of the electrode in the central portion is unlikely to increase. Therefore, the lithium ion secondary battery can suppress the increase in resistance as a whole.

When a through hole is made in a metal foil by a conventional concavo-convex roll, the metal foil sandwiched between the concavo-convex rolls is punched out so as to be torn off, so that a large number of fine metal pieces are inevitably generated. However, there is a risk of short circuit. On the other hand, by forming the through hole 34 with the above-mentioned tool 40 or the manufacturing apparatus 42, a part of the metal foil 41 is plastically worked, but the plastically worked part is left as a burr 35 and is one of the plastically machined parts. Since the through hole 34 is formed by cutting the portion, the through hole 34 can be formed without generating an unnecessary metal piece. Therefore, it is possible to obtain the metal foil 41 and the current collector to which the metal pieces do not adhere.

4. Modifications The present invention is not limited to the above embodiment, and can be appropriately modified within the scope of the gist of the present invention.

FIG. 11 is a side view showing another example of a manufacturing apparatus suitable for continuously forming a plurality of rows of through holes 34 in a long strip-shaped metal foil 41. In the manufacturing apparatus 48 shown in FIG. 11, the components equivalent to those of the manufacturing apparatus 42 shown in FIG. 9 are designated by the same reference numerals, and the description of the equivalent components will be omitted.

The manufacturing apparatus 48 is characterized in that the light reduction rolls 49 and 49 are arranged between the installation position of the rotary blade 46 and the pressing roll 45 and the adjustment reel 47 on the take-up reel 44 side. These light rolling rolls 49, 49 lightly roll the metal foil 41 and crush the burrs 35 provided in the plurality of through holes 34 formed in the metal foil 41 by the rotary blade 46 and the pressing roll 45 to crush the metal. It has a function of smoothing the foil 41.

In the case of the above embodiment, the case where the through holes 34 adjacent to each other in the width direction are arranged in a state where the positions of the through holes 34 in the length direction are aligned has been described, but the present invention is not limited to this, for example. , The positions of the through holes 34 in the length direction may be staggered. FIG. 12 shows the metal leaf 50 according to the modified example, and the through holes 52 adjacent to each other in the width direction are arranged in a state where the positions of the through holes 52 in the length direction are staggered. A current collector can be obtained by cutting out the metal foil 50 shown in this figure into a predetermined shape. That is, since the ratio (L / D) is formed to be 1.0 or less, the same effect as that of the above embodiment can be obtained.

In the case of the above embodiment, the case where the through hole 34 is formed so that its length direction is parallel to the one side of the foil main bodies 18A and 22A has been described, but the present invention is not limited to this. In the positive electrode current collector 54 and the negative electrode current collector 56 shown in FIG. 13, the through hole 58 has a direction x in which the through hole 58 is orthogonal to one side provided with the terminal connection portions 19 and 23 of the foil bodies 54A and 56A, and the through hole 58. It is formed so that the acute angle formed with the length direction is 45 ° or less, and in the case of this figure, it is 0 °. Since the current collector according to this modification is formed so that the ratio (L / D) is 1.0 or less, the same effect as that of the above embodiment can be obtained. Further, since the length direction of the through hole 58 is formed substantially parallel to the direction x, when the positive electrode current terminal 26 or the negative electrode current terminal 28 is connected, the current collector faces the terminal connection portions 19 and 23. Even when tension is applied, it is possible to prevent the stress from concentrating on the short side of the through hole 58, so that the breakage of the current collector can be further suppressed.

In the case of the above embodiment, the case where the ratio (L / D) of the length L in the length direction and the distance D in the length direction of the through hole 34 is generally constant has been described, but the present invention describes this. However, the ratio may be changed. In the metal leaf 59 shown in FIG. 14, a first through-hole row in which through-holes 34 formed so as to have a ratio (L / D) of 1.0 or less are arranged in a row with the length directions of the through-holes 34 aligned. 60 and a second through-hole row 64 in which the through-holes 62 are arranged in a row with the length directions of the through-holes 62 aligned so that the ratio (L / D) is smaller than that of the first through-hole row 60. The first through hole row 60 and the second through hole row 64 are alternately arranged in the width direction of the through holes 34 and 62. Since the current collector according to this modification is formed so that the ratio (L / D) is 1.0 or less, the same effect as that of the above embodiment can be obtained. Further, by cutting out the metal foil 59 into a predetermined shape, the obtained current collector has through holes 34 and 62, so that the adhesion of the mixture layer can be obtained, and the resistance of the lithium ion secondary battery is increased as a whole. It can be suppressed, and by including the second through-hole row 64, the strength can be improved more reliably.

The case where the battery is applied to a lithium ion secondary battery as a power storage device has been described, but the present invention is not limited to this, and the present invention can be applied to a lithium ion capacitor, an electric double layer capacitor, an all-solid-state battery, or the like.

The material of the metal foil 41 can be appropriately selected according to the intended use, and for example, nickel or nickel alloy, silver or silver alloy may be used.

10 Lithium-ion secondary battery (power storage device)
18 Positive electrode current collector (current collector)
22 Negative electrode current collector (current collector)
26 Positive current terminal (current terminal)
28 Negative current terminal (current terminal)
34 Through hole 34A Opening 34B Long side 34C Short side 35 Bali

Claims (3)

It is provided with a foil-shaped current collector and a current terminal connected to one side of the current collector.
A plurality of slit-shaped through holes are formed in the current collector.
The through hole has a ratio (L / D) of 1.0 or less between the length (L) in the length direction and the distance (D) between the through holes adjacent to each other in the length direction of the through hole .
It has a first through-hole row in which the through-holes are arranged in a row in the same length direction, and a second through-hole row in which the ratio (L / D) is smaller than that of the first through-hole row. The through-hole rows and the second through-hole rows are alternately arranged in the width direction of the through-holes.
The through hole is composed of a pair of long side portions parallel to the length direction of the through hole and short side portions formed in a constricted shape on both end sides of the pair of long side portions. It has burrs protruding on the back surface side of the current collector on the entire circumference of the opening of the through hole.
A power storage device characterized by that. The power storage device according to claim 1 , wherein the interval (D) is 0.5 mm or more. The power storage device according to claim 1 or 2 , wherein the through hole has a length W in the width direction of 1 to 500 μm and a length L in the length direction of 10 to 5000 μm.

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