Collector plate and power storage device using same

Abstract

This collector plate is plate-shaped and includes: a first main surface; and a second main surface located on the side opposite the first main surface. The collector plate further includes: a first part at the center thereof; a plurality of second parts extending in first directions away from the first part; and a plurality of third parts extending from portions of the second parts, such portions being spaced apart from the first part, and the third parts protrude in second directions that cross the first directions. With regard to two second parts adjacent to each other, there is a gap formed between a third part extending from one of the second parts and a third part extending from the other second part.

Description

Current collector plate and power storage device using the same

[0001] The present disclosure relates to a current collector plate and an electricity storage device using the same.

[0002] 2. Description of the Related Art With the expansion of demand for in-vehicle applications, power storage devices such as secondary batteries are being required to have higher output and capacity.

[0003] As a current collection structure for obtaining high output, a so-called end surface current collection structure is being considered, in which the exposed portion of the negative electrode current collector or positive electrode current collector protrudes from the end surface of the wound electrode group and is welded to the current collecting plate.

[0004] As an example of an electricity storage device having an end-face current collection structure, for example, Patent Document 1 proposes a secondary battery having a case, an electrode assembly having an anode plate, a cathode plate, and a separator interposed between the anode plate and the cathode plate and attached within the case, a cap assembly that seals the case, and an anode current collector plate and a cathode current collector plate that are electrically connected to the anode plate and the cathode plate of the electrode assembly, respectively, and at least one of the anode current collector plate and the cathode current collector plate has a plate-shaped main body and a contact portion that protrudes from the main body and comes into contact with the corresponding anode plate or cathode plate.

[0005] Japanese Patent Application Laid-Open No. 2005-203374

[0006] As the capacity and output of the power storage device increase, the amount of gas generated during abnormal heat generation also increases, making it necessary to quickly exhaust a large amount of high-temperature gas.

[0007] The current collector plate and battery described in Patent Document 1 are designed to make it difficult to exhaust gas during abnormal heat generation, so there is a risk that the gas will not be exhausted in time after the explosion-proof valve is activated, and a high temperature state will be maintained. As a result, for example, when multiple power storage devices are arranged to form a module, the heat from the high temperature may be transmitted to adjacent power storage devices, causing damage.

[0008] One aspect of the present disclosure relates to a current collector plate having a plate shape with a first main surface and a second main surface opposite the first main surface, and having a central first portion, a plurality of second portions extending in a first direction away from the first portion, and a plurality of third portions extending from locations of the second portions spaced apart from the first portion and protruding in a second direction intersecting the first direction, wherein a gap is formed between the third portion extending from one of the second portions and the third portion extending from the other of the second portions in two adjacent second portions.

[0009] Another aspect of the present disclosure relates to an electricity storage device including: a columnar wound body in which a positive electrode and a negative electrode are wound with a separator interposed therebetween; a case that houses the wound body; and the current collector plate, wherein the battery case has a cylindrical portion and a bottom that closes one end of the cylindrical portion, and at least the first portion of the current collector plate is electrically connected to the bottom of the case on the first main surface side, and at least the second portion of the current collector plate is joined on the second main surface side to one of the positive electrode and the negative electrode at an end face of the wound body that faces the second main surface.

[0010] Use of the current collector plate of the present disclosure improves the safety of the electricity storage device.

[0011] 1A is a top view illustrating the appearance of a current collector plate according to an embodiment of the present disclosure. １ -X ２ 1 is a cross-sectional view in the direction. FIG. 2 is a perspective view showing the appearance of a current collector plate according to an embodiment of the present disclosure. FIG. 3 is a top view showing another example of a current collector plate according to an embodiment of the present disclosure. FIG. 4 is a side view showing the appearance of a battery according to an embodiment of the present disclosure. FIG. 5 is a schematic view of a battery according to an embodiment of the present disclosure, with a portion of the case cut away, showing a state in which a current collector plate is arranged in the case. FIG. 6 is a longitudinal cross-sectional view showing the configuration of particularly the bottom side of a battery according to an embodiment of the present disclosure. FIG. 7 is a perspective view showing another example of a current collector plate according to an embodiment of the present disclosure. FIG. 8 is a top view showing an enlarged view of a first portion and its periphery, showing another example of a current collector plate according to an embodiment of the present disclosure. FIG. 9 is a top view showing an enlarged view of a first portion and its periphery, showing another example of a current collector plate according to an embodiment of the present disclosure. FIG. 10 is a schematic cross-sectional view showing another example of a current collector plate according to an embodiment of the present disclosure.

[0012] Hereinafter, embodiments of the present disclosure will be described. Note that in the following description, examples of embodiments of the present disclosure will be described, but the present disclosure is not limited to the examples described below. In the following description, specific numerical values, materials, etc. may be exemplified, but other numerical values, materials, etc. may be applied as long as the effects of the present disclosure can be obtained.

[0013] A current collector plate according to an embodiment of the present disclosure is plate-shaped and has a first main surface and a second main surface opposite the first main surface. The current collector plate has a central first portion and a plurality of second portions extending in a first direction away from the first portion. The current collector plate further has a plurality of third portions in each of the second portions extending from a location on the second portion spaced apart from the first portion and projecting in a second direction intersecting the first direction.

[0014] The current collector plate is provided in an electricity storage device such as a battery (e.g., a secondary battery). The electricity storage device includes, for example, a case having a cylindrical portion and a bottom portion that closes one end of the cylindrical portion. A columnar wound body in which a positive electrode and a negative electrode are wound with a separator interposed therebetween is housed in the case, with one end face of the wound body facing the bottom. The other end of the cylindrical portion of the case has an opening. The opening of the case is closed with the wound body housed therein and maintained airtight. Note that the method for sealing the opening of the case is not particularly limited, and any known method can be used.

[0015] In this case, the current collector is disposed between the bottom and the wound body such that the first main surface of the current collector faces the bottom of the case and the second main surface of the current collector faces the end face of the wound body. The current collector is electrically connected to either the positive electrode or the negative electrode at the end face of the wound body and is also electrically connected to the bottom.

[0016] The current collector plate may be electrically connected to either the positive electrode or the negative electrode depending on the configuration of the power storage device, i.e., the current collector plate may be either a positive electrode current collector plate or a negative electrode current collector plate.

[0017] The bottom of the case may be provided with an explosion-proof mechanism, such as a thin section or markings. When abnormal heat generation occurs and the internal pressure rises above a predetermined threshold due to generated gas, the explosion-proof mechanism is activated, and the generated gas is exhausted to the outside of the case. This stops the abnormal heat generation. However, if a current collector plate is disposed between the bottom and the winding body, the shape of the current collector plate may hinder the gas exhaust, slowing down the gas exhaust speed. As a result, the abnormal heat generation cannot be stopped immediately, and the heat caused by the abnormal heat generation may affect the outside (for example, an adjacent power storage device).

[0018] The second portions of the current collector plate extend from the central first portion in a first direction away from the first portion while being spaced apart. In other words, the multiple second portions extend, for example, radially from the first portion, with the first portion as the center. When the current collector plate is placed in the case, the first portion is located at the center of the bottom, and the second portions extend from the center of the bottom toward the cylindrical portion. Hereinafter, the first direction in which the second portions extend may be referred to as the "radial direction."

[0019] The third portion extends from a location of the second portion spaced apart from the first portion and extends (for example, along the circumferential direction of the tubular portion) so as to protrude in a second direction intersecting the first direction. In two adjacent second portions, the third portion extending from one second portion is spaced apart from the third portion extending from the other second portion, forming a gap. Radial gaps are interposed between the third portions and between the second portions. These gaps function as exhaust paths for exhausting generated gas in the event of abnormal heat generation.

[0020] Therefore, by using a current collector plate having the second and third portions, gas generated during abnormal heat generation can be exhausted at high speed, and the abnormal heat generation state can be stopped immediately.

[0021] Additionally, the third portion has the effect of holding the winding body within the case when gas is exhausted. This is because the provision of the third portion increases the rigidity of the current collector plate at the location where the third portion is provided. Furthermore, the formation of a gap between the third portions extending from adjacent second portions allows the third portions to more actively penetrate into the exposed current collector portion of the winding body to which they are electrically connected. This deeper penetration more firmly fixes the current collector plate to the exposed current collector portion and reduces the electrical resistance between the third portion and the exposed current collector portion.

[0022] In order not to obstruct gas exhaust, the explosion-proof mechanism provided at the bottom of the case is preferably provided in a region that is more inward than the third portion and does not overlap with the third portion. In other words, the third portion preferably extends more outward than the region where the explosion-proof mechanism is provided, protruding in the second direction intersecting the radial direction. However, it is sufficient that the explosion-proof mechanism is located inside the outermost periphery of the third portion. In this case, it is sufficient that at least a portion of the third portion is located outside the region where the explosion-proof mechanism is formed at the bottom. Increasing the proportion of the portion of the third portion that is located outside the explosion-proof mechanism further enhances the effect of holding the wound body within the case.

[0023] The number of second portions may be two or more. In the case of a current collector plate having two second portions, the two second portions may extend from the first portion in opposite directions. In this case, the shape of the current collector plate when viewed from the first main surface or the second main surface may be I-shaped.

[0024] The winding may have three or more second portions. In this case, a gap is provided between adjacent second portions and between adjacent third portions, and the gap between the second portions is wider than the gap between the third portions. In this case, the current collector plate is configured to easily and efficiently exhaust gas generated in the event of abnormal heat generation while pressing down on the winding body.

[0025] When the current collector plate has three or more second portions, the second portions may be arranged at equiangular positions in the circumferential direction, but are not limited thereto. That is, the angles formed between adjacent second portions among the multiple second portions may be the same. The number of second portions is preferably three or more in order to efficiently exert the effect of the third portion in holding the wound body. On the other hand, the number of second portions may be, for example, six or less in order to efficiently exhaust gas and to facilitate the manufacture of the energy storage device. In particular, a current collector plate having four second portions and third portions protruding from each of the four second portions can highly effectively hold the wound body and efficiently exhaust gas.

[0026] The second portion may have a radially extending portion that protrudes toward the second main surface. This protruding portion toward the second main surface is a recess when viewed from the first main surface, and the recess extends radially to form a groove. When a current collector is disposed between the bottom and the wound body, the current collector can preferentially contact the wound body at this groove. This allows electrical connection between the current collector and one electrode of the wound body via the groove. The electrical connection can be achieved, for example, by pressing the current collector against the wound body so that the groove contacts the one electrode, and then welding the one electrode to the current collector at the groove. Furthermore, because this protruding portion is recessed when viewed from the first main surface, the thickness of the protruding portion can be suppressed.

[0027] The thickness of the current collector plate may be, for example, in the range of 0.1 mm to 1.0 mm. In this case, the first portion may be thicker than the second portion. This thickness relationship can prevent the laser from penetrating the first portion when joining the first portion to the bottom of the case. Furthermore, when joining the second portion to the exposed current collector portion of the electrode in the wound body, it can prevent the exposed current collector portion from being subjected to excessive heat damage. It can also prevent molten material from the second portion from penetrating into the interior of the wound body. For example, the thickness of the second portion (particularly the bottom of the groove) may be 0.3 mm, and the thickness of the first portion may be 0.4 mm.

[0028] The first portion may have a protruding surface that protrudes toward the first main surface. When the current collector plate is disposed between the bottom portion and the wound body, the first portion may come into contact with the bottom portion at this protruding surface. Therefore, the current collector plate and the case can be electrically connected at the protruding surface. The electrical connection can be made, for example, by laser welding from the outside of the case. In this case, the weld mark formed by laser welding may be annular when viewed from the first main surface or the second main surface, or may be at least one point. Alternatively, the connection may be made by resistance welding or cold welding from the inside of the case.

[0029] The outer periphery of the first portion may have an annular protruding portion toward the second main surface facing the wound body and / or an annular recessed portion toward the second main surface. The annular protruding portion prevents the current collector exposed portion from displacing toward the center of the first portion. Furthermore, the current collector exposed portion recessing into the annular recessed portion prevents the current collector exposed portion from displacing toward the center of the first portion. This configuration allows the first portion to be joined to the case without affecting the bonding state between the second portion and the current collector exposed portion. Furthermore, because the displacement of the current collector exposed portion is suppressed, tilting of the electrode within the wound body and variation in the distance between adjacent positive and negative electrodes within the wound body are suppressed. Note that, when the first portion has such an annular protruding portion or annular recessed portion, the current collector exposed portion does not necessarily have to abut the annular protruding portion or recess into the annular recessed portion.

[0030] A through-hole may be provided in the first portion to further promote gas discharge and to facilitate the injection of electrolyte during the manufacturing process. The through-hole may be provided in an area of ​​the first portion where welding to the bottom of the case is not planned. Furthermore, the through-hole may improve the circulation of electrolyte. The through-hole may be positioned so as not to overlap an imaginary line (or imaginary area) connecting the joint between the first portion and the bottom and the groove in the second portion by the shortest distance. In this case, the current flowing between the groove electrically connected to the wound body and the joint is prevented from bypassing the through-hole. This shortens the current collection path between the groove and the joint.

[0031] The current collector plate may further have a plating layer laminated on each of the first and second main surfaces. In this case, the thickness of the plating layer laminated on the first main surface side may be thinner than the thickness of the plating layer laminated on the second main surface side. In this case, if the metal constituting the plating layer is a highly reflective metal, the plating layer on the first main surface side is prevented from reflecting the laser when welding by irradiating a laser from outside the case. Examples of the material (base layer) of the current collector plate include iron, stainless steel, copper, etc. when connecting to the negative electrode, and aluminum, iron, etc. when connecting to the positive electrode. Examples of the plating layer include nickel, etc. In the current collector plate of the present disclosure, this plating layer is not essential.

[0032] The electrical connection between the current collector and one electrode of the winding body may be made primarily in the second portion. Meanwhile, the electrical connection between the current collector and the case may be made primarily in the first portion. The third portion may also contribute to the electrical connection between the current collector and the case or one electrode of the winding body. For example, a protrusion that protrudes toward the first main surface may be formed on part of the third portion (e.g., a tip end in a protruding direction protruding from the second portion) so that the current collector and the case can be electrically connected in the third portion.

[0033] If the third portion has a protrusion that protrudes toward the first main surface, a recess may be formed on the surface of the case bottom facing the first main surface. The recess engages with the protrusion on the third portion. This improves the electrical connection between the current collector plate and the case and also improves the effectiveness of holding the wound body within the case when gas is exhausted in the event of abnormal heat generation.

[0034] The power storage device according to an embodiment of the present disclosure is suitable for use as, for example, a non-aqueous electrolyte secondary battery, an alkaline storage battery, or a capacitor, and contributes to increasing the output of the non-aqueous electrolyte battery. Non-aqueous electrolyte batteries include lithium ion secondary batteries and all-solid-state batteries.

[0035] An energy storage device according to an embodiment of the present disclosure includes a cylindrical wound body formed by winding a positive electrode and a negative electrode with a separator interposed therebetween, a case for accommodating the wound body, and the current collector plate. The case has a cylindrical portion and a bottom portion closing one end of the cylindrical portion. At least a first portion of the current collector plate is electrically connected to the bottom portion of the case on the first main surface side, and at least a second portion of the current collector plate is electrically connected to one of the positive electrode and the negative electrode on the end face of the wound body facing the second main surface on the second main surface side.

[0036] The other of the positive and negative electrodes of the wound body is usually electrically connected to a terminal plate disposed on the other end of the cylindrical portion. The terminal plate closes an opening formed at the other end of the cylindrical portion. The space between the opening of the cylindrical portion and the terminal plate is airtightly sealed. The sealing method is not particularly limited, and known methods can be used.

[0037] The method of electrically connecting the other electrode of the positive and negative electrodes of the wound body to the terminal plate is not particularly limited, and may be achieved by attaching one end of an internal lead to the other electrode and connecting the other end of the internal lead to the terminal plate, or may be achieved via a current collector plate.

[0038] When the other of the positive and negative electrodes of the wound body is electrically connected to the terminal plate via a current collector, the current collector interposed between the bottom of the case and one of the positive and negative electrodes of the wound body is referred to as the first current collector. In contrast, the current collector interposed between the terminal plate and the other of the positive and negative electrodes of the wound body is referred to as the second current collector, to distinguish between the two. As described above, the first current collector is a current collector having a first portion, a second portion, and a third portion.

[0039] The second current collector plate may be a current collector plate of a conventional configuration, or may be a current collector plate having a first portion, a second portion, and a third portion, similar to the first current collector plate. When the second current collector plate has a configuration similar to that of the first current collector plate, the first main surface is the surface facing the terminal plate, and the second main surface is the surface opposite to the first main surface facing the winding body, whereby the first portion, the second portion, and the third portion are defined.

[0040] By using the second current collecting plate having the first, second, and third portions, gas can be quickly discharged from the terminal plate side in addition to the case bottom when abnormal heat is generated, making it easier to immediately stop the abnormal heat generation.

[0041] The size of the power storage device (battery) is not particularly limited, and the outer diameter of the case may be, for example, 18 mm or more, 21 mm or more, or 46 mm or more. The larger the outer diameter of the battery, the higher the output, but the greater the amount of gas generated during abnormal heat generation. Therefore, using the current collector plate of the present disclosure is effective. Furthermore, the ratio of the area of ​​the area where an explosion-proof mechanism (e.g., an explosion-proof valve) is formed on the bottom to the area of ​​the bottom of the case may be 90% or less, or may be 80% or less. The area of ​​the area where the explosion-proof mechanism is formed is the area of ​​a circumscribed circle centered on the center of the bottom and tangent to the periphery of the explosion-proof mechanism when the bottom is viewed from the axial direction (height direction) of the case.

[0042] Furthermore, the current collector plate of the present disclosure can be employed in any structure of an electricity storage device, regardless of whether it is a primary battery or a secondary battery, and regardless of the configuration of the positive electrode and negative electrode.

[0043] Hereinafter, a current collector plate according to an embodiment of the present disclosure will be specifically described with reference to the drawings, taking as an example a case where it is used in a lithium ion secondary battery, which is an example of a power storage device.

[0044] 1A, 1B, and 2 are diagrams illustrating an example of a configuration of a current collector plate according to an embodiment of the present disclosure. Fig. 1A is a top view illustrating the appearance of the current collector plate, and Fig. 1B is a diagram illustrating the X in Fig. 1A. １ -X ２ 2 is a perspective view of the current collector plate as viewed from the first main surface side (the bottom side of the case).

[0045] The current collecting plate 40 has a central first portion 41, a plurality of second portions 42 extending radially along a first direction (radial direction) away from the first portion 41, and a plurality of third portions 43 extending from a location of each second portion 42 spaced apart from the first portion 41 and protruding in a second direction (circumferential direction) intersecting the first direction. In adjacent second portions 42, the third portion extending from one second portion toward the other second portion is spaced apart from the third portion extending from the other second portion toward the one second portion. In other words, a gap is formed between the third portion extending from one second portion and the third portion extending from the other second portion.

[0046] The current collector 40 is plate-shaped and has a first main surface S1 and a second main surface S2 opposite (backside of) the first main surface S1. The current collector 40 is, for example, a metal plate that is punched into a predetermined shape and then processed by press forming into a shape with projections and recesses. When the current collector 40 is placed in a battery, it is placed between the bottom of the case and the wound body so that the first main surface S1 faces the bottom of the case and the second main surface S2 faces the wound body. Note that FIG. 2 shows the appearance of the current collector as viewed from the first main surface S1 side (the bottom side of the case).

[0047] 1A, 1B, and 2, the first portion 41 has a protruding surface 41S that protrudes toward the first main surface S1. The protruding surface 41S contacts the bottom surface of the battery case, electrically connecting the current collector plate 40 to the case.

[0048] On the other hand, the second portion 42 has a protruding surface 42S that protrudes toward the second main surface S2. This protruding surface extends in the direction in which the second portion 42 extends, and when viewed from the first main surface side, a groove 42A is formed that extends in the direction in which the second portion 42 extends. The current collector plate 40 and one electrode of the wound body are electrically connected in the groove 42A.

[0049] A gap G is present between adjacent second portions 42 and between adjacent third portions 43 that are continuous from adjacent second portions 42. Gas generated during abnormal heat generation can be efficiently released through this gap G. Because adjacent third portions 43 extend from the tip of the second portion 42 so as to approach each other, the width of the gap G between the second portions 42 is wider than the width of the gap G between the third portions 43.

[0050] The third part 43 extends in a direction approximately perpendicular to the direction in which the second part 42 extends, protruding on both sides from the second part 42, thereby having the effect of holding and fixing the wound body so that it does not fly out of the case.

[0051] 1A, 1B, and 2, in the current collecting plate 40, four second portions 42 extend radially from the first portion 41 at 90° angles to each other. In addition, the third portion 43 extends from the tip of the second portion 42 while receding toward the first portion 41, so that the overall shape of the second portion and the third portion 43 connected to the second portion forms an arrowhead. As a result, as can be seen from FIG. 1A, a portion of the outline of each of the multiple third portions 43 is in contact with a predetermined square R. As a result, the overall outline shape of the current collecting plate 40 is a shape inscribed in a square.

[0052] In this case, it is possible to achieve a high level of both the effect of fixing the wound body and the effect of efficiently exhausting gas by using the current collecting plate 40. In addition, since the current collecting plate 40 has a contour shape inscribed in a square, residue is reduced when manufacturing the current collecting plate 40 by punching a metal plate, improving production efficiency.

[0053] 3A and 3B are diagrams showing another example of the configuration of a current collector plate according to an embodiment of the present disclosure, and show top views of the current collector plate as viewed from the first main surface side (case bottom side).

[0054] 3A is an example in which the third portion 43 is arranged to extend in an arc shape from the tip of the second portion 42. In this example, the arc-shaped third portion 43 can be arranged to extend along the inner circumferential wall of the battery case when placed inside the battery.

[0055] 3B is an example of a current collector plate 40B having three second portions 42 extending from a first portion 41. In the current collector plate 40B, the three second portions 42 extend radially from the first portion 41 at angles of 120° to each other. The third portion 43 is arranged to extend in an arc shape from the tip of the second portion 42. The arc-shaped third portion 43 can be arranged to extend along the inner circumferential wall of the battery case when placed inside the battery.

[0056] Fig. 4 is a side view showing the appearance of the battery 200 according to this embodiment, with the current collector plate 40 disposed therein. Fig. 5 is a schematic diagram showing a state in which the case 210 and the current collector plate 40 are disposed, with a portion of the case 210 cut away. Fig. 6 is a vertical cross-sectional view showing the internal structure of the battery 200 on the bottom side of the case 210.

[0057] Battery 200 includes a wound body 100 formed into a columnar shape by winding a positive electrode 10 and a negative electrode 20 with a separator 30 interposed therebetween, a non-aqueous electrolyte (not shown), a metal case 210 with a bottom that houses wound body 100 and the non-aqueous electrolyte, and a sealing plate 220 that seals the opening of case 210. Although not shown in Figures 4 and 5, a gasket is disposed around the periphery of sealing plate 220, and the inside of case 210 is sealed by crimping the open end of case 210 to the gasket.

[0058] The positive electrode 10 is in the form of a long sheet and includes a positive electrode current collector and a positive electrode active material layer supported thereon. The positive electrode active material layer is formed on both sides of the positive electrode current collector. However, one longitudinal end of the positive electrode current collector may have a positive electrode current collector exposed portion that does not have a positive electrode active material layer. The positive electrode may be electrically connected to a sealing plate via the positive electrode current collector exposed portion. In other words, the sealing plate functions as an external positive electrode terminal. The other longitudinal end of the positive electrode current collector is covered with an insulating layer 13.

[0059] The negative electrode 20 is in the form of a long sheet and includes a negative electrode current collector and a negative electrode active material layer supported on the negative electrode current collector. The negative electrode active material layer is formed on both sides of the negative electrode current collector. However, one end along the longitudinal direction of the negative electrode current collector is formed with a negative electrode current collector exposed portion 21x that does not have the negative electrode active material layer.

[0060] A current collector 40 (negative electrode current collector) is disposed between the bottom of the case 210 and the wound body 100. A first portion 41 of the current collector 40 protrudes toward the first main surface S1 and is in contact with the bottom of the case 210. The current collector 40 is welded to the bottom of the case 210 at the contact point.

[0061] The current collector 40 has a groove 42A formed in the second portion 42, which protrudes toward the second main surface S1 opposite the first main surface S1, and the groove 42A abuts against the negative current collector exposed portion 21x. The current collector 40 and the negative current collector exposed portion 21x are welded to each other at the groove 42A. Therefore, the case 210 functions as an external negative terminal.

[0062] A thin-walled portion 210X is provided at the bottom of the case 210. When abnormal heat generation occurs, the internal pressure of the battery increases, and if the internal pressure exceeds a predetermined threshold, the case 210 breaks at the thin-walled portion 210X, allowing gas to be exhausted. The third portion 43 of the current collector plate 40 serves to fix the wound body 100 within the case 210 as the gas is exhausted. The third portion 43 also extends further outward than the thin-walled portion 210X so as not to impede gas exhaust.

[0063] 5 and 6, the inner surface of the bottom of case 210 is not flat, but has an annular recess 210A on the outer periphery. In this case, the tip of third portion 43 of current collecting plate 40 may protrude toward first main surface S1 so as to engage with recess 210A. This brings the protruding portion of third portion 43 into contact with case 210, improving the electrical connection between current collecting plate 40 and case 210 and enhancing the effect of fixing the wound body during gas exhaust in the event of abnormal heat generation.

[0064] In order to facilitate the injection of the electrolyte solution during manufacturing and to further facilitate the discharge of gas in the event of abnormal heat generation, a through-hole may be provided in the first portion 41. Since the first portion 41 faces the hollow region of the core of the wound body 100, providing a through-hole in the first portion 41 and forming a gas discharge path makes it easier to discharge gas from the hollow region.

[0065] 7 shows an example of a current collector plate 40C in which a protruding portion 43A protruding toward the first main surface S1 is provided at the tip of the third portion 43, and a through hole 41H is provided in the first portion 41. In FIG. 7, the third portion 43 extending in the second direction is bent at the tip to form the protruding portion 43A protruding toward the first main surface S1. The protruding portion 43A is not limited to this configuration, and for example, the third portion 43 may be made thicker at the tip to protrude toward the first main surface S1. Furthermore, in the example of FIG. 7, the through hole 41H is provided at the center of the protruding surface 41S of the first portion 41, but this is not limiting, and the through hole 41H may be provided in a region of the protruding surface 41S that is outer circumferential of the position where the first portion 41 is welded to the case bottom. However, in this case, the through hole 41H may be provided in a position that does not face the groove portion 42A in the circumferential direction (for example, in a position that faces the gap G) so that the through hole 41H does not lengthen the current path that flows from the groove portion 42A to the case via the first part 41.

[0066] 8A and 8B show another example of a current collector plate in which a through hole 41H is provided in the first portion 41. FIGS. 8A and 8B are top views showing enlarged views of the periphery of the first portion of the current collector plate. In the example of FIGS. 8A and 8B, the through hole 41H is provided on the inner circumferential side of the welding position 41X with the case bottom. The through hole 41H may be cross-shaped as shown in FIG. 8A, and its shape is not particularly limited. Furthermore, a plurality of through holes 41H may be arranged as shown in FIG. 8B.

[0067] The material constituting the current collector 40 is determined depending on the materials constituting the positive and negative electrodes. For example, when used as a negative electrode current collector of a lithium ion secondary battery, the material of the current collector 40 is, for example, copper, copper alloy, nickel, stainless steel, etc. The material of the negative electrode current collector may be the same as the material of the negative electrode current collector 21. For example, when used as a positive electrode current collector of a lithium ion secondary battery, the material of the current collector 40 is, for example, aluminum, aluminum alloy, titanium, stainless steel, etc. The material of the positive electrode current collector may be the same as the material of the positive electrode current collector.

[0068] The exposed portion of the current collector and the current collecting plate 40 can be joined by, for example, laser welding. The laser may be irradiated radially from the opposite side of the current collecting plate's surface facing the end face of the winding 100 (i.e., the first main surface side) to multiple locations along the groove 42A. At this time, a weld mark extending in a first direction (the radial direction of the winding) is formed in the second portion 42 of the current collecting plate 40. Of the two ends of this weld mark in the first direction, the first end on the first portion side may be the welding start point (the point where welding begins), and the second end farther from the first portion than the first end may be the welding end point. By welding the second portion 42 of the current collecting plate 40 in this manner, the temperature of the second portion is higher when welding the outside of the second portion than when welding the inside of the second portion, making the outside of the second portion 42 more likely to melt during welding. This improves the reliability of the radial welding at the joint between the outside of the second portion 42 of the current collecting plate 40 and one of the positive and negative electrodes. By improving the welding reliability at the outside of the current collector plate 40 and the wound body 100, it is possible to suppress a deterioration in resistance when current is collected from the wound body 100 to the current collector plate 40. When the radially extending second portion 42 is joined to the wound body 100, the distance between the connection points with the second portion is longer in the winding direction of the current collection path of the wound body 100 at the outer portion than at the inner portion of the wound body. Therefore, the current collection path in the winding direction is longer at the outer portion of the wound body 100. If a welding defect occurs at the outer portion of the second portion 42, the current collection path within the wound body is more likely to be longer than if a welding defect occurs at the inner portion, and the current collection resistance of the power storage device 200 is more likely to deteriorate. Therefore, by improving the welding reliability at the outer portion of the second portion 42 of the current collector plate 40 in the radial direction than at the inner portion, it is possible to suppress a deterioration in current collection resistance when current is collected from the wound body 100 to the current collector plate 40.

[0069] FIG. 9 is a schematic cross-sectional view showing a current collector plate 40c, which is another example of the current collector plate 40 in this embodiment.

[0070] Furthermore, the second portion 42 of the current collector plate 40c may have a first region on the inside and a second region on the outside of the first region in the first direction (radial direction), and may be bent so that the second region is located closer to the wound body 100 than the first region. With this configuration, the second region of the second portion 42 actively abuts against the outside of the wound body 100, thereby improving the reliability of welding between the outside of the wound body 100 and the current collector plate 40.

[0071] (Positive Electrode) A sheet-shaped metal material is used for the positive electrode current collector. The sheet-shaped metal material may be a metal foil, a porous metal, an etched metal, or the like. Examples of the metal material that can be used include aluminum, an aluminum alloy, nickel, and titanium. The thickness of the positive electrode current collector is, for example, 10 μm to 100 μm.

[0072] The positive electrode active material layer includes, for example, a positive electrode active material, a conductive material, and a binder. The positive electrode active material layer can be obtained, for example, by applying a positive electrode mixture slurry including the positive electrode active material, the conductive material, and the binder to both sides of a positive electrode current collector, drying the coating, and then rolling. The positive electrode active material is a material that absorbs and releases lithium ions. Examples of positive electrode active materials include lithium-containing transition metal oxides, transition metal fluorides, polyanions, fluorinated polyanions, and transition metal sulfides.

[0073] (Negative Electrode) A sheet-shaped metal material is used for the negative electrode current collector. The sheet-shaped metal material may be a metal foil, a porous metal, an etched metal, or the like. Examples of the metal material that can be used include copper, a copper alloy, nickel, and stainless steel. The thickness of the negative electrode current collector is, for example, 10 μm to 100 μm.

[0074] The negative electrode active material layer contains, for example, a negative electrode active material, a conductive agent, and a binder. The negative electrode active material layer is obtained, for example, by applying a negative electrode mixture slurry containing the negative electrode active material, a conductive agent, and a binder to both sides of a negative electrode current collector, drying the coating, and then rolling it. The negative electrode active material is a material that absorbs and releases lithium ions. Examples of negative electrode active materials include carbon materials, metal compounds, alloys, and ceramic materials.

[0075] (Separator) The separator may be, for example, a microporous film made of a resin such as polyolefin, a woven fabric, a nonwoven fabric, etc. The thickness of the separator is, for example, 10 to 300 μm, and preferably 10 to 40 μm.

[0076] (Non-aqueous Electrolyte) The non-aqueous electrolyte has lithium ion conductivity and contains a lithium salt and a non-aqueous solvent that dissolves the lithium salt.

[0077] The current collector plate according to the present disclosure can be used to realize a high-output electricity storage device, and is therefore suitable for use in vehicles, for example.

[0078] 100: Wound body 10: Positive electrode 13: Insulating layer 20: Negative electrode 21x: Exposed portion of negative electrode current collector 30: Separator 40, 40A to 40C: Current collector plate 41: First portion 41S: Protruding surface 42: Second portion 42A: Groove portion 42S: Protruding surface 43: Third portion 43A: Protruding portion 200: Battery (electricity storage device) 210: Case 210A: Recess 210X: Thin portion

Claims

1. It is plate-shaped and has a first main surface and a second main surface on the side opposite to the first main surface, a central first portion, a plurality of second portions extending in a first direction away from the first portion, and a plurality of third portions extending from a position of the second portion spaced apart from the first portion and protruding in a second direction intersecting the first direction, wherein a gap is formed between the third portion extending from one of the two adjacent second portions and the third portion extending from the other second portion, a current collector plate.

2. It has three or more of the second portions, gaps are interposed between the adjacent second portions and between the adjacent third portions, and the gap between the second portions is wider than the gap between the third portions, The current collector plate according to claim 1.

3. A groove portion extending in the first direction while protruding toward the second main surface side is formed in the second portion, The current collector plate according to claim 1.

4. The first portion has a protruding surface protruding toward the first main surface side, The current collector plate according to claim 1.

5. Four of the second portions extend radially from the first portion so as to form an angle of 90° with each other, A part of the contour of each of the plurality of third portions is in contact with a predetermined square, The current collector plate according to any one of claims 1 to 4.

6. The third portion has a protruding portion protruding toward the first main surface side, The current collector plate according to any one of claims 1 to 4.

7. The first portion has a through hole, The current collector plate according to any one of claims 1 to 4.

8. It further has a plating layer laminated on the first main surface and the second main surface, The thickness of the plating layer on the first main surface side is thinner than the thickness of the plating layer on the second main surface side, The current collector plate according to any one of claims 1 to 4.

9. A columnar wound body in which a positive electrode and a negative electrode are wound with a separator interposed therebetween, a case for housing the wound body, and the current collector plate according to any one of claims 1 to 4, wherein the case has a cylindrical portion and a bottom portion closing one end of the cylindrical portion, at least the first portion of the current collector plate is electrically connected to the bottom portion of the case on the first main surface side, and at least the second portion of the current collector plate is joined to one of the positive electrode and the negative electrode on an end surface facing the second main surface of the wound body on the second main surface side, a power storage device.

10. An explosion-proof mechanism is provided at the bottom of the case. The explosion-proof mechanism is provided in a region on the inner circumferential side of the third portion of the current collector plate and not overlapping the third portion. The power storage device according to claim 9.

11. A recess is formed in the surface of the bottom of the case facing the first main surface. The recess is engaged with a protrusion provided on the third portion of the current collector plate. The power storage device according to claim 9.

12. The second portion of the current collector plate is joined to the one electrode by welding. A linear welding mark extending in the first direction is formed on the second portion. At both ends in the direction in which the welding mark extends, the first end of the welding mark on the first portion side is the welding start point, and the second end of the welding mark on the side far from the first portion is the welding end point. The power storage device according to claim 9.

13. The portion of the second portion of the current collector plate joined to the one electrode has, in the first direction, a first region on the first portion side and a second region located outside the first region. In the winding axis direction of the wound body, the second portion is bent such that the second region is located closer to the one electrode side than the first region. The power storage device according to claim 9.