Power storage device

Abstract

To provide a power storage device which can efficiently be manufactured at a low cost while ensuring high safety.SOLUTION: A power storage device 100 includes: a case 10; a power storage element 20 disposed inside the case 10; a lead 21 connected to an electrode of the power storage element 20; and a sealing member 40 sealing an opening of the case 10. The sealing member 40 includes: a gasket 41 including a disk-shaped base part 41a; and a conductive sealing plate 42. The base part 41a is disposed between the sealing plate 42 and the power storage element 20. The base part 41a is provided with a through-hole 41h. A protrusion 42a of the sealing plate 42 is inserted into the through-hole 41h. The protrusion 42a of the sealing plate 42 is connected to the lead 21. In accordance with a rise of internal pressure inside the case 10, the protrusion 42a is displaced in a direction away from the lead 21 so that the protrusion 42a and the lead 21 are disconnected from each other.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an electricity storage device. [Background technology]

[0002] Currently, power storage devices such as secondary batteries and capacitors are used in a variety of fields. For example, these power storage devices are used in power tools, power-assisted bicycles, electric vehicles, and the like, and efforts are being made to increase their capacity.

[0003] Electric storage devices used in various fields are required to exhibit high safety even in harsh operating environments. For this reason, secondary batteries and the like have conventionally been provided with mechanisms for ensuring safety, such as explosion-proof valves and current interruption devices (CIDs). For example, a cylindrical battery is known as a secondary battery, which includes an electrode body, a cylindrical outer can, and a sealing body that is crimped and fixed to the opening of the outer can via a gasket, and the sealing body includes a valve body that has a circular outer shape and is crimped and fixed to the gasket, a metal plate that is disposed on the inner side of the battery from the valve body and is connected to the center of the valve body, and an annular insulating member that is interposed between the outer periphery of the valve body and the outer periphery of the metal plate (for example, Patent Document 1). In this cylindrical battery, when the pressure inside the outer can increases, the pressure causes the center of the valve body to move toward the outside of the battery. This moving force causes the valve body to separate from the metal plate. Then, the connection between the valve body and the metal plate is cut off, and the current path inside the cylindrical battery can be cut off. In this cylindrical battery, at least a valve body, a metal plate, an insulating member, and a gasket are used to implement a sealing mechanism for the exterior can and a safety mechanism. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2016 / 157749 Summary of the Invention [Problem to be solved by the invention]

[0005] The above-mentioned electric storage device requires many parts to perform the functions of sealing and safety. This may deteriorate the workability when assembling the electric storage device. Therefore, a sealing member that can ensure safety with a simpler structure is required. In this situation, one of the objects of the present disclosure is to provide an electric storage device that can be efficiently manufactured at low cost and has high safety. [Means for solving the problem]

[0006] One aspect of the present disclosure relates to an energy storage device, the energy storage device including a case having a cylindrical tube portion, a bottom portion closing one end of the tube portion, and an opening portion provided at the other end of the tube portion, an energy storage element including a pair of electrodes arranged inside the case, a lead connected to one of the pair of electrodes, and a sealing member that seals the opening portion of the case, the sealing member including a gasket having insulating properties and including a disk-shaped base, and a sealing plate having electrical conductivity, the sealing plate having a displacement portion on which a protrusion protruding toward the energy storage element is formed, and an outer periphery provided around the displacement portion, the base portion is arranged between the sealing plate and the energy storage element, a through hole is formed in the base, the protrusion of the sealing plate is inserted into the through hole, and the protrusion of the sealing plate and the lead are connected to each other. Joint In response to an increase in the internal pressure of the case, the projection is displaced in a direction away from the lead, thereby causing a contact between the projection and the lead. Joint is cut off. This specification discloses the following techniques: (Technology 1) An electricity storage device including: a case having a cylindrical tube portion, a bottom portion closing one end of the tube portion, and an opening portion provided at the other end of the tube portion; an electricity storage element disposed within the case and including a pair of electrodes; a lead connected to one of the pair of electrodes; and a sealing member sealing the opening portion of the case, the sealing member includes a gasket having insulating properties and including a disk-shaped base, and a sealing plate having electrical conductivity; the sealing plate has a displacement portion on which a protrusion protruding toward the energy storage element is formed, and an outer circumferential portion provided around the displacement portion, the base is disposed between the sealing plate and the energy storage element, A through hole is formed in the base, The protrusion of the sealing plate is inserted into the through hole, the projection of the sealing plate and the lead are connected, The power storage device, wherein the projection is displaced in a direction away from the lead in response to an increase in internal pressure within the case, thereby cutting off the connection between the projection and the lead. (Technology 2) the gasket includes a rising portion extending from a peripheral edge portion of the base in a direction away from the energy storage element, and an annular folded-back portion extending from an end of the rising portion toward the inside of the case and covering at least a portion of an upper surface of an outer circumferential portion of the sealing plate, an annular groove is formed on an outer circumferential surface of the cylindrical portion of the case; an area of ​​the inner circumferential surface of the cylindrical portion where the groove is formed protrudes inwardly of the case; the sealing member is located on the groove portion, The power storage device according to Technology 1, wherein the other end of the cylindrical portion is bent toward the inside of the case and abuts against an upper surface of the folded-back portion. (Technology 3) The electricity storage device according to claim 1 or 2, wherein the sealing plate has a thin-walled portion between the current collecting portion on which the protrusions are formed and the outer periphery, the thin-walled portion being thinner than the current collecting portion and the outer periphery. (Technology 4) 4. The electricity storage device according to any one of Techniques 1 to 3, wherein an inner circumferential surface of the through hole is inclined so that the through hole becomes narrower as it approaches the lead. (Technology 5) The electricity storage device according to any one of Techniques 1 to 4, wherein the base has an air hole formed therein for transmitting the internal pressure of the case to the sealing plate. (Technology 6) The energy storage device according to any one of techniques 1 to 5, wherein the through hole has a longitudinal direction along a first direction, and the protrusion of the sealing plate has a longitudinal direction along the first direction when viewed from the bottom of the case. (Technology 7) the lead includes a strip-shaped portion connected to the projection of the sealing plate, the strip portion and the projection are connected by a weld; The power storage device according to claim 6, wherein the welded portion has a longitudinal direction along the first direction when viewed from the bottom of the case. (Technology 8) the lead includes a strip-shaped portion connected to the projection of the sealing plate, The power storage device according to claim 6, wherein one edge of the lead in the extending direction intersects with the first direction when viewed from the bottom of the case. (Technology 9) The electricity storage device according to any one of Techniques 1 to 8, wherein at least one rib is provided on the surface of the base on the lead side. (Technology 10) The at least one rib includes two ribs arranged to sandwich the through hole, The power storage device according to claim 9, wherein the lead includes a strip-shaped portion that is disposed between the two ribs and connected to the protrusion of the sealing plate. (Technology 11) the lead includes a wide portion connected to the strip portion and having a width greater than that of the strip portion; The power storage device according to technique 10, wherein the width of the wide portion is greater than the distance between the two ribs. (Technology 12) The lead includes two wide portions connected to both ends of the strip portion, respectively, and each wide portion is wider than the strip portion; The width of each of the two wide portions is wider than the distance between the two ribs, The power storage device according to technique 10, wherein the lead is arranged such that the two wide portions sandwich at least a portion of the two ribs. Effect of the Invention

[0007] According to the present disclosure, the number of parts performing sealing and safety functions is reduced, and therefore it is possible to obtain a safe electricity storage device that can be manufactured efficiently at low cost. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view illustrating a schematic example of an electricity storage device according to the present disclosure. [Diagram 2] 2 is a perspective view showing a schematic diagram of a sealing member and a lead used in the electricity storage device shown in FIG. 1. [Diagram 3] 2 is a perspective view showing a gasket of a sealing member and a lead used in the electricity storage device shown in FIG. 1 with a part cut away. FIG. [Figure 4] FIG. 2 is a top view diagrammatically illustrating the power storage device illustrated in FIG. [Diagram 5] 1. FIG. 4 is a bottom view diagrammatically illustrating another example of a sealing member and a lead used in the electricity storage device shown in FIG. [Figure 6] 1. FIG. 4 is a bottom view diagrammatically illustrating another example of a sealing member and a lead used in the electricity storage device shown in FIG. [Figure 7] 2A to 2C are cross-sectional views each showing a schematic process for manufacturing the electricity storage device shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] In the following, the embodiment of the present disclosure will be described with reference to examples, but the present disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be exemplified, but other numerical values ​​and materials may be applied as long as the effects of the present disclosure can be obtained.

[0010] (Electricity storage device) The energy storage device of the present disclosure includes a case having a cylindrical tube portion, a bottom portion closing one end of the tube portion, and an opening portion provided at the other end of the tube portion, an energy storage element including a pair of electrodes arranged within the case, a lead connected to one of the pair of electrodes, and a sealing member that seals the opening portion of the case. The sealing member includes a gasket having insulating properties and including a disk-shaped base, and a sealing plate having electrical conductivity. The sealing plate has a displacement portion formed with a protrusion protruding toward the energy storage element, and an outer periphery provided around the displacement portion. The base portion of the gasket is arranged between the sealing plate and the energy storage element. A through hole is formed in the base portion. The protrusion of the sealing plate is inserted into the through hole. The protrusion of the sealing plate and the lead are connected. As the internal pressure in the case increases, the protrusion is displaced away from the lead, thereby breaking the connection between the protrusion and the lead. Hereinafter, the through hole formed in the disc-shaped base of the gasket may be referred to as the "through hole (G)", and the protrusion of the sealing plate inserted into the through hole (G) may be referred to as the "protrusion (P)".

[0011] In the electricity storage device of the present disclosure, the displacement portion (protrusion (P)) of the sealing plate is displaced in a direction away from the lead in response to an increase in the internal pressure inside the case. Then, by displacing the protrusion (P) of the sealing plate in a direction away from the lead, it is possible to cut off the connection between the protrusion (P) of the sealing plate and the lead. That is, it is possible to make the sealing plate and the lead function as a current interrupt device (CID). This CID cuts off the current collection path in the electricity storage device when the pressure inside the case exceeds a predetermined value due to gas accumulation in the case caused by overcharging or the like. By cutting off the current collection path, it is possible to stop charging and discharging the electricity storage device with increased pressure. Then, it is possible to prevent the electricity storage device from becoming unsafe and bursting due to increased pressure.

[0012] Furthermore, in the energy storage device of the present disclosure, in addition to the above-mentioned CID function, when the internal pressure in the case further increases, the sealing plate may break to release the gas in the case to the outside of the case. Such a sealing plate prevents the energy storage device of the present disclosure from exploding. Therefore, safety is further improved. The sealing member of the present disclosure has a smaller number of parts and a simpler structure than conventional sealing members that perform the above-mentioned functions. Therefore, the present disclosure provides an energy storage device that achieves reduced manufacturing costs and assembly man-hours while maintaining safety.

[0013] Furthermore, since the sealing member of the present disclosure has a small number of parts, the volume of the parts can be reduced compared to conventional sealing members that perform similar functions, and therefore the energy density of the power storage device of the present disclosure can be increased compared to conventional power storage devices.

[0014] The power storage device may be a secondary battery or a capacitor. The power storage device may be a non-aqueous electrolyte secondary battery (lithium ion secondary battery, lithium battery, etc.), a nickel-hydrogen secondary battery, etc. The power storage device may be an electric double layer capacitor using activated carbon as an electrode material, or a lithium ion capacitor, etc.

[0015] The storage element is not particularly limited and may be selected according to the type of the storage device. A known storage element may be used for the storage element. For example, when the storage device is a secondary battery, a storage element including a positive electrode, a negative electrode, a separator, and an electrolyte may be used. The negative electrode of an example lithium ion secondary battery includes a material that reversibly absorbs and releases lithium ions as a negative electrode active material. Examples of the negative electrode active material include carbon materials such as graphite, and inorganic compounds such as silicon and titanium oxide. The positive electrode of these secondary batteries may include a transition metal composite oxide containing lithium as a positive electrode active material. The transition metal composite oxide includes elements such as nickel, manganese, cobalt, and aluminum.

[0016] When the power storage device is a capacitor, a power storage element including two electrodes, an electrolyte, and a separator may be used. These components can be selected according to the type of capacitor.

[0017] (case) The case may function as, for example, one of the electrode terminals. When the case functions as an electrode terminal, for example, the case may be formed using a metal having electrical conductivity, and one electrode of the power storage element (an electrode not electrically connected to the sealing plate) may be electrically connected to the case. For example, the negative electrode and the case may be electrically connected. In the power storage device of the present disclosure, the positive electrode may be connected to the case.

[0018] The case has a cylindrical tube portion, a bottom portion that closes an opening at one end of the tube portion, and an opening portion at the other end of the tube portion. The tube portion may have an annular groove portion that protrudes from the outer peripheral surface of the case toward the inner peripheral surface of the case in the radial direction of the tube portion. A sealing member can be disposed on the groove portion. The open end of the case is bent toward the inside of the tube portion (toward the central axis of the tube portion) in the radial direction of the tube portion by crimping. Furthermore, the bent open end is crimped to the outer peripheral portion of the sealing plate via a folded portion of a gasket of the sealing member described later. The crimped open end and the groove portion can sandwich the sealing member. Thereby, the opening of the case is sealed. For example, a metal case can be used for the case. This metal case may be made of aluminum, iron, nickel copper, or an alloy or clad material of these metals. The case of the power storage device is not limited to the above configuration and may be a known case.

[0019] (Lead) The lead electrically connects the electrode of the energy storage element and the sealing plate. The lead may be a lead used in a known energy storage device. The lead may be a strip-shaped metal foil. Examples of the metal (conductive metal) constituting the lead include aluminum, iron, nickel, copper, or an alloy or clad material made of a plurality of these metals. One end of the lead may be connected to either of the two electrodes of the energy storage element, but when the energy storage device is a secondary battery, for example, the lead is connected to the positive electrode.

[0020] The other end of the lead or its vicinity is connected (fixed) to the sealing plate. That is, the lead is electrically and physically connected to the sealing plate. There is no particular limitation on the method of connecting the lead and the sealing plate, and welding, for example, may be used. However, in order to function as a CID, the connection method must be such that the connection between the lead and the sealing plate is released (i.e., the fixation is released) when the force pulling the lead and the sealing plate apart becomes large. When joining the lead and the sealing plate by welding, 、 The force required to separate the lead and the sealing plate can be adjusted by changing the conditions such as the weld area and the weld depth. There are no particular limitations on the welding method, and laser welding, resistance welding, friction stir welding, ultrasonic welding, etc. may be used.

[0021] From the viewpoint of reducing the number of parts, it is preferable that the lead is directly connected to the sealing plate, however, the lead and the sealing plate may be indirectly connected via a conductive member as long as the lead can function as a CID.

[0022] (Sealing board) The sealing plate is, for example, a circular plate having electrical conductivity. The sealing plate may function as an electrode terminal, or may function as a displacement member that electrically connects an electrode terminal (for example, a terminal cap) and a lead. The sealing plate is, for example, formed of a metal plate, such as aluminum, nickel, copper, iron, or an alloy or clad material composed of a plurality of these metals. A known sealing plate (such as a valve) can be used as the sealing plate.

[0023] The sealing plate may have a displacement portion that is displaced in response to the internal pressure in the case, and an outer peripheral portion formed around the displacement portion. The displacement portion is formed with a current collecting portion having a protrusion that protrudes toward the lead. The tip of the protrusion may be located at (or in the vicinity of) the opening of the through hole (G) on the side of the energy storage element, or may be located closer to the energy storage element than the opening of the through hole (G).

[0024] The displacement portion of the sealing plate may be displaced by a pressure equal to or greater than a predetermined value within the case. In this case, the displacement portion may have a thin wall portion formed therein that is thinner than the outer periphery. For example, the sealing plate may include a thin wall portion between the portion (current collecting portion) where the protrusion (P) is formed and the outer periphery, the thin wall portion being thinner than the current collecting portion and the outer periphery. The displacement portion may be configured, for example, in a disk shape or a dome shape. When the sealing plate includes a dome-shaped displacement portion, the dome-shaped displacement portion is disposed so as to be convex toward the energy storage element. In order to increase the displacement of the protrusion (P), the protrusion (P) may be formed, for example, in the center of the displacement portion of the sealing plate (the center of the current collecting portion).

[0025] The shape of the tip surface of the protrusion (the surface to which the lead is connected) may be a shape having a longitudinal direction along the direction in which the region of the lead facing the sealing member extends. With this configuration, the bonding area of ​​the lead to be bonded to the protrusion of the sealing plate can be easily expanded without expanding the area of ​​the lead to all four sides. Therefore, the bonding strength between the lead and the protrusion can be easily increased. In addition, the distance from the edge of the lead to the bonded region to the bonded region is likely to be short. Therefore, when the sealing plate is displaced, the bonded region is less likely to bend. Therefore, when the sealing plate is displaced, the lead is less likely to follow. The width of the tip surface having the longitudinal direction may be narrower than the width of the part of the lead connected to the tip surface. That is, for example, the entire tip surface of the protrusion may be covered by the lead. In addition, in the displacement portion, the thickness of the part (current collecting portion) where the protrusion is formed may be thicker than the other regions. This configuration can prevent delays in the activation timing of the CID compared to protrusions formed such that the rear surface of the protrusion (the upper surface of the sealing plate) at the displacement portion is recessed by a dimension substantially equal to the protruding height of the protrusion.

[0026] If the internal pressure in the case increases further and the displacement of the sealing plate becomes particularly large after the CID function is activated and the sealing plate and the leads are broken, the thin portion of the sealing plate may break and the gas inside the case may be released to the outside of the case, thereby preventing the case from bursting.

[0027] (gasket) The gasket is formed of a material having elasticity and insulating properties to function as a gasket. That is, the gasket has insulating properties. The gasket may be formed of a known material used for gaskets of secondary batteries or capacitors. Examples of the gasket material include polypropylene (PP), polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), perfluoroalkoxyalkane (PFA), and polyether ether ketone (PEEK). Additives (for example, known additives) may be added to these materials as necessary. There is no limitation on the method of forming the gasket, and it may be formed by a method such as injection molding.

[0028] The gasket includes, for example, a rising portion extending from the peripheral edge of the base in a direction away from the energy storage element, and an annular folded portion extending from an end of the rising portion toward the inside of the case (toward the central axis of the case) and covering at least a part of the upper surface of the outer periphery of the sealing plate. The rising portion and the folded portion are disposed between the inner periphery near the open end of the case and the sealing plate, and insulate the case from the sealing plate.

[0029] The cross-sectional shape of the through hole (G) formed in the base of the gasket (the cross-sectional shape perpendicular to the thickness direction of the base of the gasket) is not particularly limited as long as the protrusion of the sealing plate can be inserted. The shape of the through hole may be, for example, a circle, an ellipse, a rectangle (including a square), or a rectangle with rounded corners. The shape of the opening of the through hole may also be a shape with a longitudinal direction parallel to the longitudinal direction of the tip surface in accordance with the shape of the protrusion having the longitudinal direction. In order to suppress the lead from following when the displacement part of the sealing plate is displaced, the gap between the opening on the lead side and the protrusion (P) in the through hole (G) of the gasket may be reduced. Therefore, when the protrusion of the sealing plate and the gasket are viewed from the side of the energy storage element, the outer shape of the protrusion and the shape of the opening of the through hole of the gasket may be approximately the same size and shape. The position of the through hole corresponds to the position of the protrusion of the sealing plate. The through hole may be formed, for example, in the center of the disk-shaped base or in the vicinity thereof.

[0030] The power storage device of the present disclosure may satisfy the following configurations (1) and (2). (1) The gasket includes a raised portion extending from the peripheral edge of the base in a direction away from the energy storage element, and an annular folded portion extending from an end of the raised portion (the end farther from the energy storage element) toward the inside of the case (toward the central axis of the case) and covering at least a portion of the upper surface of the outer periphery of the sealing plate. (2) An annular groove is formed on the outer peripheral surface of the cylindrical portion of the case, and the area on the inner peripheral surface of the cylindrical portion where the groove is formed protrudes inwardly of the case. The sealing member is positioned on the groove, and the other end of the cylindrical portion is bent inwardly of the case and abuts against the upper surface of the folded-back portion. Here, the upper surface means the surface that is farther from the energy storage element.

[0031] The sealing plate may have a thin portion between the current collecting portion on which the protrusions are formed and the outer periphery, the thin portion being thinner than the current collecting portion and the outer periphery.

[0032] The inner circumferential surface (side surface) of the through hole (G) may be inclined so that the through hole (G) becomes narrower as it approaches the lead. That is, the inner circumferential surface of the through hole of the gasket may have a tapered shape that becomes narrower from the sealing plate side toward the energy storage element side. By using a through hole of such a shape, the displacement of the protrusion (P) of the sealing plate becomes smooth, and the reliability of the CID in the energy storage device is improved.

[0033] When the through hole of the gasket has the above-mentioned tapered shape, the outer peripheral surface of the protrusion (P) of the sealing plate may also have a tapered shape that becomes thinner toward the energy storage element. With this configuration, the protrusion (P) of the sealing plate can be smoothly displaced, improving the reliability of the CID in the energy storage device.

[0034] The outer peripheral surface of the protrusion (P) of the sealing plate may contact the inner peripheral surface of the through hole (G). According to this configuration, since the protrusion (P) can be held by the gasket, it is possible to suppress the breakage of the sealing plate and the lead when the CID is not in operation. Alternatively, a gap may be formed between the outer peripheral surface of the protrusion and the inner peripheral surface of the through hole (G). That is, the protrusion may have a shape such that at least a part of the protrusion does not contact the inner peripheral surface of the through hole (G). According to this configuration, it is possible to suppress the transfer of heat from the protrusion to the gasket when the lead is welded to the protrusion. As a result, it is possible to suppress problems caused by the gasket being deformed by heat (for example, problems related to the displacement of the sealing plate, etc.).

[0035] The base of the gasket may have a vent hole formed therein for transmitting the internal pressure in the case to the sealing plate. It is also possible to transmit the internal pressure in the case to the sealing plate only through the through hole (G) into which the protrusion (P) of the sealing plate is inserted. However, by forming the vent hole, the internal pressure in the case can be transmitted to the sealing plate quickly and reliably. In this case, the vent hole may be provided at a position that does not overlap with the lead. This configuration can prevent the lead from blocking the vent hole when gas flows into the vent hole. However, in the power storage device of the present disclosure, the vent hole may be provided at a position that overlaps with the lead if there is no consideration of the risk of the lead blocking the vent hole.

[0036] The through hole (G) may have a longitudinal direction along one direction (first direction), and the protrusion (P) of the sealing plate may have a longitudinal direction along the first direction when viewed from the bottom of the case. Hereinafter, the first direction may be referred to as the "first direction D1."

[0037] The lead may include a strip connected to a protrusion (P) of the sealing plate, and the strip and the protrusion (P) may be connected by a weld, and the weld may have a longitudinal direction along a first direction D1 when viewed from the bottom of the case.

[0038] The lead may include a strip-shaped portion connected to the projection (P) of the sealing plate, and an edge at one end in the direction in which the lead extends may intersect with the first direction D1 when viewed from the bottom of the case.

[0039] At least one rib (e.g., multiple ribs) may be provided on the surface of the base of the gasket on the lead side. By providing the rib, the rigidity of the base of the gasket can be increased, and when the CID operates, the lead is less likely to follow the displacement of the sealing plate. Furthermore, by providing the rib, a part of the lead can be engaged with the rib, and when the CID operates, the lead is less likely to follow the displacement of the sealing plate. Therefore, the reliability of the CID function can be improved. In addition, the rib can also facilitate the positioning of the lead when connecting the lead to the sealing plate. Therefore, the lead is prevented from being displaced and causing stress to be applied to the joint between the lead and the sealing plate. Furthermore, when an air hole is formed in the gasket, the air hole and the lead can be prevented from overlapping.

[0040] The movement of the lead may be suppressed by interference between the lead and at least one of the ribs. That is, the movement of the lead may be suppressed by being locked to the rib. When the lead is displaced following the displacement of the protrusion (P) of the sealing plate, the connection between the sealing plate and the lead may be difficult to release even if the displacement of the protrusion (P) becomes large. The reliability of the CID can be improved by suppressing the displacement of the lead by interference between the rib formed on the gasket and the lead. When the displacement of the lead is suppressed by interference between the lead and the rib, the distance between the lead and the rib at the position of interference may be in the range of 0 to 0.6 mm.

[0041] At least one rib formed on the base of the gasket may include two ribs arranged to sandwich the through hole (G) of the base. The lead may include a strip-shaped portion arranged between the two ribs and connected to the protrusion (P) of the sealing plate. As examples of the arrangement of the lead and the ribs in this case, first and second examples are described below. The two ribs may be arranged approximately parallel to each other. In this specification, approximately parallel means that they are arranged parallel or at an angle close to parallel, and for example, the angle between the directions in which the two ribs extend is 10° or less.

[0042] In the first example, the lead and the two ribs may have the following configuration. The lead includes a wide portion that is connected to the strip portion (for example, one end of the strip portion in the longitudinal direction) and is wider than the strip portion. The width of the wide portion is wider than the distance between the two ribs. With this configuration, the rib engages with an area of ​​the periphery of the wide portion that faces the rib. Therefore, the lead is less likely to be displaced when the sealing plate is displaced. Note that in this configuration, the number of ribs does not need to be two. Even if there is only one rib, it is possible to suppress the displacement of the lead compared to a configuration without any ribs. Note that in this case, the edges of the wide portion and the strip portion may be shaped by connecting multiple straight lines, or may include curved lines.

[0043] In the second example, the lead and the two ribs may have the following configuration. The lead includes two wide parts that are connected to both ends of the strip (for example, one end in the longitudinal direction of the strip and the other end opposite thereto) and are wider than the strip. The width of each of the two wide parts is wider than the distance between the two ribs. The lead is arranged so that the two wide parts sandwich at least a part of the two ribs. With this configuration, the area of ​​the periphery of the wide part that faces the ribs is engaged with the ribs. This engagement makes it difficult for the lead to be displaced when the sealing plate is displaced. The lead is connected (fixed) to the sealing plate. In other words, it can be said that notches are formed at both ends in the width direction of the strip, and the two ribs are housed in this pair of notches. The number of notches and ribs does not need to be two. Even if there is only one notch and one rib, the lead is less likely to be displaced than in a configuration without a rib and a notch. The rib may be columnar and fill most of the notch, or may extend along the edge of the notch, and the edge of the notch may be rectangular, U-shaped, V-shaped, or C-shaped.

[0044] Also, a through hole may be formed in the strip-shaped portion of the lead, and the rib may be fitted into the through hole. In this case, the through hole formed in the lead may be a round hole or a rectangular hole. Also, when the gasket and the lead are viewed from the electrode group side, the shape of the hole and the shape of the rib may be substantially the same, and the rib may be smaller than the opening of the hole. When the through hole of the strip-shaped portion is fitted into the rib, the lead may be press-fitted into the rib. This allows the lead to be fixed more firmly to the gasket. In addition, when the sealing plate and the lead are viewed from the electrode group side, the through hole of the lead may be arranged side by side with the tip surface of the protrusion in the longitudinal direction of the strip-shaped portion.

[0045] The power storage device of the present disclosure may include a terminal cap (not shown) connected to the sealing plate. The terminal cap may be made of a conductive material (e.g., a conductive metal) and may include a protruding portion that functions as a terminal. The terminal cap may include a flat donut-shaped portion and a protruding portion formed in the center of the portion. The terminal cap is disposed on the opposite side of the sealing plate from the power storage element. That is, the sealing plate is disposed between the terminal cap and the power storage element. In one example, the peripheral portion of the terminal cap and the peripheral portion of the sealing plate are overlapped, and the two peripheral portions are crimped at the opening end of the case via a gasket. In this case, the terminal cap may be formed with a vent hole for releasing gas inside the case when the sealing plate is broken.

[0046] One aspect of the present disclosure relates to the above-mentioned sealing member. As described above, the sealing member according to the present disclosure includes a gasket including a disk-shaped base and a sealing plate having electrical conductivity, the base is disposed between the sealing plate and an energy storage element, a through hole (G) is formed in the base, and a protrusion (P) provided on a displacement portion of the sealing plate is inserted into the through hole (G).

[0047] An example of the power storage device of the present disclosure and an example of a manufacturing method thereof will be specifically described below with reference to the drawings, but the power storage device of the present disclosure is not limited to the following content. The components described above can be applied to the components of the example power storage device described below. In addition, the components of the example power storage device described below may be changed based on the above description, and components that are not essential to the power storage device of the present disclosure may be omitted. In addition, the matters described below may be applied to the above embodiment.

[0048] (Embodiment 1) In the first embodiment, an example of an energy storage device of the present disclosure will be described. A cross-sectional view of an energy storage device 100 of the first embodiment is shown in Fig. 1. The energy storage device 100 includes a case 10, an energy storage element 20 arranged in the case 10, leads 21 and 22 connected to electrodes (not shown) of the energy storage element 20, and a sealing member 40 that seals an opening of the case 10. The energy storage device 100 further includes insulating plates 23 and 24. The insulating plates 23 and 24 are each a disk-shaped member having a through hole formed therein.

[0049] The sealing member 40 includes a gasket 41 including a disk-shaped base 41a, and a sealing plate 42. The base 41a is disposed between the sealing plate 42 and the energy storage element 20. A through hole 41h is formed in the center of the base 41a. The base 41a has a planar shape that is approximately the same size as the planar shape (circular) of the sealing plate 42. The peripheral edge of the base 41a and the peripheral edge of the sealing plate 42 are in close contact with each other.

[0050] The case 10 has a cylindrical tube portion 10b, a bottom portion 10c that closes one end of the tube portion 10b, and an opening portion 10d that constitutes the other end (open end) of the tube portion 10b. In the vicinity of the opening portion 10d of the tube portion 10b, an annular groove portion 10a that protrudes from the outside of the case 10 toward the inside of the case 10 in the radial direction of the tube portion 10b is formed. The sealing member 40 is disposed on the inner peripheral surface of the groove portion 10a. The opening end of the opening portion 10d of the case 10 is crimped to the outer peripheral portion of the sealing plate 42 via a gasket 41. As a result, the sealing member 40 is sandwiched between the groove portion 10a and the opening end, and the case 10 is sealed.

[0051] The gasket 41 includes a rising portion 41b extending from the peripheral edge of the base portion 41a in a direction away from the energy storage element 20, and an annular folded portion 41d extending from the end of the rising portion 41b toward the inside of the case 10 and covering at least a portion of the upper surface of the outer circumferential portion 42p of the sealing plate 42.

[0052] The sealing plate 42 includes a dome-shaped displacement portion 42d that is convex toward the energy storage element 20, and an outer peripheral portion 42p that is provided around the displacement portion 42d. At least a part of the displacement portion 42d is thinned so that the displacement portion 42d breaks when the displacement of the displacement portion 42d becomes large. A current collector portion is provided in a central portion (current collector portion) 42c of the displacement portion 42d, on which a protrusion 42a protruding toward the energy storage element 20 is formed. The protrusion 42a of the sealing plate 42 is inserted into a through hole 41h of the gasket 41. The tip surface of the protrusion 42a may be on the same plane as or in the vicinity of the surface 41s of the gasket 41 that faces the energy storage element 20, or may protrude toward the energy storage element 20 beyond the surface 41s. The lead 21 is fixed (connected) to the tip surface of the protrusion 42a.

[0053] The sealing plate 42 has a thin portion 42t that is thinner than the outer periphery 42p. More specifically, the sealing plate 42 has the thin portion 42t between the central portion 42c where the protrusions 42a are formed and the outer periphery 42p.

[0054] In the first embodiment, an example in which there is no gap between the protrusion 42a and the through hole 41h is shown, but there may be a gap between them. That is, the protrusion 42a and the side surface (inner circumferential surface) of the through hole 41h may not be in contact with each other. In addition, in the first embodiment, an example in which the shape of the opening of the through hole 41h is an ellipse having a longitudinal direction along the first direction D1, and the shape of the tip surface of the protrusion 42a is a shape having a longitudinal direction parallel to the longitudinal direction of the opening of the through hole 41h is shown, but these may be other shapes as described above. For example, the protrusion 42a and the through hole 41h may each be a truncated cone shape.

[0055] A connection portion C (eg, a welded portion) between the projection 42a and the lead 21 may have a longitudinal direction along the first direction D1 as shown in FIGS.

[0056] Fig. 2 is a schematic perspective view of the leads 21 and the sealing member 40 as viewed from the surface 41s side. Fig. 3 is a schematic partially exploded perspective view in which a part of the gasket 41 and the leads 21 in Fig. 2 have been removed. Fig. 4 is a schematic top view of the electricity storage device 100 as viewed from the sealing plate 42 side. The cross-sectional view in Fig. 1 is a cross-sectional view taken along the longitudinal direction of the ridge-like protrusions 42a shown in Fig. 3.

[0057] 2 and 3, a plurality of ventilation holes (through holes) 41c are formed in the base portion 41a of the gasket 41. The ventilation holes 41c communicate with the displacement portion 42d so that the internal pressure in the case 10 is transmitted to the displacement portion 42d.

[0058] Two ribs 41r arranged substantially parallel to each other with a through hole 41h therebetween are formed on a surface 41s of the base portion 41a of the gasket 41. Each of the ribs 41r extends in a direction parallel to the longitudinal direction (first direction D1) of the projection 42a.

[0059] The rib 41r is, for example, a linear protrusion. The lead 21 includes a strip-shaped portion 21a disposed between the two ribs 41r. The shape of the tip surface of the protrusion 42a is smaller than the planar shape of the strip-shaped portion 21a. A part of the strip-shaped portion 21a is fixed to the tip surface of the protrusion 42a by welding or the like.

[0060] When the internal pressure inside the case 10 increases, the protrusion 42a of the displacement portion 42d moves in a direction away from the energy storage element 20 (i.e., in a direction away from the lead 21). On the other hand, the movement of the lead 21 is suppressed by the base portion 41a. Therefore, when the displacement of the protrusion 42a becomes large, the connection between the protrusion 42a and the lead 21 breaks, and the connection is released. As a result, overcharging and the like are suppressed.

[0061] When the internal pressure of the case 10 increases further and the displacement of the displacement portion 42d becomes even larger, the thin-walled portion 42t or its peripheral portion breaks. As a result, the gas inside the case 10 is released to the outside of the case 10.

[0062] In the structure shown in Fig. 2 and Fig. 3, the movement of the strip portion 21a is suppressed by the rib 41r. Specifically, the movement of the strip portion 21a in a direction perpendicular to the longitudinal direction of the strip portion 21a (parallel to the first direction D1) is suppressed. Furthermore, the movement of the strip portion 21a in the longitudinal direction of the strip portion 21a may be suppressed by interference between the lead 21 and the rib 41r. A first example of such a configuration is shown typically in Fig. 5, and a second example is shown typically in Fig. 6. Figs. 5 and 6 are views of a part of the lead 21 and the gasket 41 as viewed from the surface 41s side, respectively.

[0063] In the example shown in FIG. 5, the lead 21 includes a strip portion 21a disposed between two ribs 41r, and a wide portion 21b connected to one end of the strip portion 21a and wider than the width Wa of the strip portion 21a. Such a lead 21 can be formed by cutting a single metal plate into a predetermined shape (the same applies to the lead 21 shown in FIG. 6). The width Wb of the wide portion 21b is wider than the distance L between the two ribs 41r. Therefore, the movement of the strip portion 21a is suppressed by the interference between the wide portion 21b and the two ribs 41r. In the example shown in FIG. 5, the strip portion 21a is suppressed from moving in the direction of the arrow A. At this time, the rib 41r extends while being bent in a crank shape (step shape) along the peripheral shape of the lead 21.

[0064] In one example shown in FIG. 6, the lead 21 includes a strip portion 21a disposed between two ribs 41r, and two wide portions 21b connected to both ends of the strip portion 21a in the longitudinal direction and wider than the width Wa of the strip portion 21a. The two wide portions 21b are disposed to sandwich at least a part of the two ribs 41r. The widths Wb of the two wide portions 21b are each wider than the distance L between the two ribs 41r. Therefore, the movement of the strip portion 21a is suppressed by the interference between the two wide portions 21b and the two ribs 41r. In the example shown in FIG. 6, the movement of the strip portion 21a in the directions of the arrows A and B is suppressed. The widths Wb of the two wide portions 21b may be the same or different.

[0065] In the above example, one edge of the lead 21 in the extending direction intersects with the first direction D1 when viewed from the bottom 10c of the case 10.

[0066] An example of a method for manufacturing the energy storage device 100 shown in FIG. 1 is described below. First, the structure in the state of FIG. 7 is formed. The groove portion 10a is formed after the energy storage element 20 is placed in the case 10. The lead 21 is connected to one of the electrodes of the energy storage element 20 and the protrusion 42a. The lead 22 is connected to the case 10. Next, the open end of the case 10 is folded inward, and the cylindrical wall portion of the gasket 41 is sandwiched between the gasket 41 and the outer periphery 42p of the sealing plate 42 is crimped. By this process, the folded portion 41d is formed from the cylindrical wall portion. In this manner, the energy storage device 100 can be manufactured. These steps can be applied to steps used in known methods for manufacturing energy storage devices. [Industrial Applicability]

[0067] The present disclosure can be used for an electricity storage device. [Explanation of symbols]

[0068] 10 Cases 20 Energy storage element 21, 22 Lead 40 Sealing material 41 Gasket 41a base 41b Rising part 41c Ventilation hole 41d Folded part 41h through hole 41r Rib 42 Sealing plate 42a protrusion 42d Displacement section 100 Electricity storage device Connection C (welded section)

Claims

1. An electricity storage device including: a case having a cylindrical tube portion, a bottom portion closing one end of the tube portion, and an opening portion provided at the other end of the tube portion; an electricity storage element disposed within the case and including a pair of electrodes; a lead connected to one of the pair of electrodes; and a sealing member sealing the opening portion of the case, the sealing member includes a gasket having insulating properties and including a disk-shaped base, and a sealing plate having electrical conductivity; the sealing plate has a displacement portion on which a protrusion protruding toward the energy storage element is formed, and an outer circumferential portion provided around the displacement portion, the base is disposed between the sealing plate and the energy storage element, A through hole is formed in the base, The protrusion of the sealing plate is inserted into the through hole, the projection of the sealing plate and the lead are joined together, When the internal pressure in the case increases, the projection is displaced in a direction away from the lead, and the connection between the projection and the lead is broken. At least one rib is provided on the surface of the base portion on the lead side, The at least one rib includes two ribs arranged to sandwich the through hole, the lead includes a strip portion disposed between the two ribs and joined to the protrusion of the sealing plate; the lead includes a wide portion connected to the strip portion and having a width greater than that of the strip portion; The width of the wide portion is greater than the distance between the two ribs.

2. An electricity storage device including: a case having a cylindrical tube portion, a bottom portion closing one end of the tube portion, and an opening portion provided at the other end of the tube portion; an electricity storage element disposed within the case and including a pair of electrodes; a lead connected to one of the pair of electrodes; and a sealing member sealing the opening portion of the case, the sealing member includes a gasket having insulating properties and including a disk-shaped base, and a sealing plate having electrical conductivity; the sealing plate has a displacement portion on which a protrusion protruding toward the energy storage element is formed, and an outer circumferential portion provided around the displacement portion, the base is disposed between the sealing plate and the energy storage element, A through hole is formed in the base, The protrusion of the sealing plate is inserted into the through hole, the projection of the sealing plate and the lead are joined together, When the internal pressure in the case increases, the projection is displaced in a direction away from the lead, and the connection between the projection and the lead is broken. At least one rib is provided on the surface of the base portion on the lead side, The at least one rib includes two ribs arranged to sandwich the through hole, the lead includes a strip portion disposed between the two ribs and joined to the protrusion of the sealing plate; The lead includes two wide portions connected to both ends of the strip portion, the two wide portions being wider than the strip portion; The width of each of the two wide portions is wider than the distance between the two ribs, The lead is arranged such that the two wide portions sandwich at least a portion of the two ribs.

3. the gasket includes a rising portion extending from a peripheral edge portion of the base in a direction away from the energy storage element, and an annular folded-back portion extending from an end of the rising portion toward the inside of the case and covering at least a portion of an upper surface of an outer circumferential portion of the sealing plate, an annular groove is formed on an outer circumferential surface of the cylindrical portion of the case; an area of ​​the inner circumferential surface of the cylindrical portion where the groove is formed protrudes inwardly of the case; the sealing member is located on the groove portion, The power storage device according to claim 1 , wherein the other end of the cylindrical portion is bent inwardly of the case and abuts against an upper surface of the folded-back portion.

4. The power storage device according to any one of claims 1 to 3, wherein the sealing plate has a thin-walled portion between the current collecting portion on which the protrusion is formed and the outer periphery, the thin-walled portion being thinner than the current collecting portion and the outer periphery.

5. 5. The power storage device according to claim 1, wherein an inner circumferential surface of the through hole is inclined so that the through hole becomes narrower as it approaches the lead.

6. The power storage device according to any one of claims 1 to 5, wherein the base portion has an air hole formed therein for transmitting internal pressure in the case to the sealing plate.

7. The storage device according to any one of claims 1 to 6, wherein the through hole has a longitudinal direction along a first direction, and the protrusion of the sealing plate has a longitudinal direction along the first direction when viewed from the bottom of the case.

8. the belt-like portion and the projection are joined by a weld, The power storage device according to claim 7 , wherein the welded portion has a longitudinal direction along the first direction when viewed from the bottom of the case.

9. The power storage device according to claim 7 , wherein an edge at one end in a direction in which the lead extends intersects with the first direction when viewed from the bottom of the case.

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