JP2022022659A - Power storage device - Google Patents

Abstract

To provide a power storage device having a novel mechanism which can reduce internal pressure inside a case when the internal pressure inside the case excessively rises.SOLUTION: A power storage device 100 includes: a case 10 which includes a cylindrical part 10a and a bottom part 10b, and has an opening part 10h; a power storage element 20 disposed inside the case 10; a sealing member 30 disposed in the opening part 10h; and a collector member 40 electrically connected to the power storage element 20. The collector member 40 includes: a tabular part 41; a columnar part 42; and a bonding part 43 which bonds the tabular part 41 to the columnar part 42. The opening part 10h is sealed with the sealing member 30 and the collector member 40. The bonding part 43 breaks when internal pressure inside the case 10 rises to reach a value within a predetermined range, thereby causing a material inside the case 10 to be discharged to the outside of the case 10.SELECTED DRAWING: Figure 1

Description

The present invention relates to a power storage device.

An electric double layer capacitor is known as an example of a power storage device. Compared to secondary batteries, electric double layer capacitors have a longer life, can be charged quickly, and have excellent output characteristics. Therefore, electric storage devices such as electric double layer capacitors are widely used as a power source for backup.

Patent Document 1 (International Publication No. 2013/08874) has an external terminal portion, an exterior body, and an insertion hole into which the external terminal portion is inserted, and a sealing port in which the opening portion of the exterior body portion is sealed together with the external terminal portion. Discloses a power storage device comprising a member.

Conventionally, the power storage device has adopted a mechanism that cuts off the current or discharges the gas inside the case to the outside of the case when the internal pressure inside the case rises.

International Publication No. 2013/08874

Currently, there is a demand for a new mechanism that cuts off the current when the internal pressure inside the case rises. In such a situation, one of the purposes of the present disclosure is to provide a new mechanism capable of reducing the internal pressure in the case or interrupting the current when the internal pressure in the case rises excessively. It is to provide a power storage device equipped with the device.

One aspect of the present disclosure relates to a power storage device. The power storage device includes a tubular portion and a bottom portion that closes one end of the tubular portion, and has a case having an opening at the other end of the tubular portion, a storage element arranged in the case, and the opening. The current collecting member includes a sealing member arranged in the portion and a current collecting member electrically connected to the power storage element, and the current collecting member includes a plate-shaped portion, a columnar portion, and the plate-shaped portion and the columnar portion. The opening is sealed by the sealing member and the current collecting member, including a joint portion for joining the portions, and when the internal pressure in the case rises and reaches a value within a predetermined range. When the joint is broken, the substance inside the case is released to the outside of the case.

Another aspect of the disclosure relates to other power storage devices. The other storage device includes a tubular portion and a bottom portion that closes one end of the tubular portion, and has a case having an opening at the other end of the tubular portion, a storage element arranged in the case, and the like. The current collecting member includes a sealing member arranged in the opening and a current collecting member electrically connected to the power storage element, and the current collecting member includes a plate-shaped portion, a columnar portion, and the plate-shaped portion. The opening is sealed by the sealing member and the current collecting member, and the internal pressure in the case rises to reach a value in a predetermined range, including a joint portion for joining the columnar portion. When the joint portion is broken, the electrical connection between the plate-shaped portion and the columnar portion is cut off.

According to the present disclosure, when the internal pressure in the case rises excessively, a power storage device having a new mechanism capable of reducing the internal pressure in the case or interrupting the current can be obtained.

It is sectional drawing which shows typically the example of the power storage device which concerns on this disclosure. FIG. 3 is a top view schematically showing an example of a current collector used in the power storage device shown in FIG. 1. It is a top view schematically showing an example of the sealing member used for the power storage device shown in FIG. 1. It is a schematic diagram for demonstrating the function of the power storage device shown in FIG. It is another schematic diagram for demonstrating the function of the power storage device shown in FIG. 1. It is sectional drawing for demonstrating an example of the structure of the power storage device which concerns on this disclosure. It is a schematic diagram for demonstrating the function of an example of the power storage device which concerns on this disclosure. It is sectional drawing which shows typically another example of the current collector used in the power storage device which concerns on this disclosure.

Hereinafter, embodiments according to 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. In the following specification, when the term "numerical value A to numerical value B" is used, the numerical value A and the numerical value B are included in the range.

(First and second power storage devices)
The first and second power storage devices according to the present disclosure will be described below. In this specification, the first and second power storage devices according to the present disclosure may be collectively referred to as "the power storage device according to the present disclosure" or "the power storage device of the present disclosure". The first and second power storage devices according to the present disclosure include a tubular portion and a bottom portion that closes one end of the tubular portion, respectively, and a case having an opening at the other end of the tubular portion and a case arranged in the case. It includes a power storage element, a sealing member arranged at the opening, and a power collection member electrically connected to the power storage element. Hereinafter, the current collector member may be referred to as a "current collector member (C)". Further, the opening of the case may be referred to as an "opening (O)". The current collector member (C) includes a plate-shaped portion, a columnar portion, and a joint portion for joining the plate-shaped portion and the columnar portion. The joint portion may be referred to as a "joint portion (B)" below. The opening (O) is sealed by a sealing member and a current collecting member.

In the first power storage device according to the present disclosure, when the internal pressure inside the case rises and reaches a value within a predetermined range, the joint portion (B) breaks, so that the substance inside the case is released to the outside of the case. Will be done. On the other hand, in the second power storage device according to the present disclosure, when the internal pressure in the case rises and reaches a value in a predetermined range, the joint portion (B) breaks, so that the plate-shaped portion and the columnar portion are formed. The electrical connection is cut off. Except for this point, there is no difference between the first power storage device and the second power storage device. The description other than this point can be applied to both the first and second power storage devices. In the power storage device according to the present disclosure, when the internal pressure inside the case rises and reaches a value within a predetermined range, the joint portion (B) breaks, so that the substance inside the case is released to the outside of the case. At the same time, the electrical connection between the plate-shaped portion and the columnar portion may be cut off.

In the following, the portion that separates the inside and the outside of the power storage device and holds the substance inside the case may be referred to as an “exterior body”. The exterior body is composed of a case having an opening (O) and a member for sealing the opening (O). The exterior body prevents a part of the power storage element (for example, an electrolytic solution) from leaking to the outside of the power storage device in a normal time. The member that seals the opening (O) includes a part of the current collector member (C) and a sealing member. In one example, the columnar portion of the current collector member (C) and the sealing member function as members for sealing the opening (O).

The current collector member (C) is electrically connected to an electrode included in the power storage element. For example, the plate-shaped portion of the current collector member (C) is electrically connected to one of the pair of electrodes included in the power storage element. The columnar portion of the current collector member (C) may function as an electrode terminal of the power storage device.

The joint (B) is designed to break when the internal pressure in the case rises and reaches a value within a predetermined range. The predetermined range may be referred to as "range X" below. Further, the internal pressure inside the case when the joint portion (B) breaks may be referred to as a “predetermined value”. From another point of view, the joint (B) breaks when the internal pressure in the case becomes higher than the pressure at which the joint (B) breaks. In the first power storage device, when the joint portion (B) breaks, a substance (gas or the like) inside the case is released to the outside of the case, and the internal pressure inside the case decreases. By reducing the pressure inside the case, it is possible to prevent the case from being greatly deformed and torn. On the other hand, in the second power storage device, the electrical connection between the plate-shaped portion and the columnar portion is cut off by breaking the joint portion (B).

As described above, the joint (B) is designed to break when the internal pressure in the case reaches a value within the range X. The lower limit value of the range X is a value at which the joint portion (B) is designed so that the joint portion (B) does not break up to that value. The upper limit value of the range X is a value in which the joint portion (B) is designed so that the joint portion (B) breaks before the internal pressure in the case exceeds the value. Since the internal pressure in the case when the joint portion (B) breaks varies, the range X has a certain width.

The value of the range X is appropriately set according to the type and application of the power storage device. The lower limit of the range X is higher than the internal pressure in the case during normal use. The upper limit of the range X is set, for example, lower than the internal pressure at which the case bursts. The range X may be, for example, 1.2 MPa or more, or 1.7 MPa or more. The range X may be, for example, 3.0 MPa or less, or 1.8 MPa or less. These lower limit values and upper limit values can be arbitrarily combined. For example, the range X may be in the range of 1.2 MPa to 3.0 MPa (for example, the range of 1.2 MPa to 1.8 MPa).

The range X depends on the area of the plate-shaped portion in contact with the joint, the area of the columnar portion in contact with the joint, the material of the joint, the shape (for example, thickness) of the joint, the method of forming the joint, and the like. Can be changed.

In the first and second power storage devices according to the present disclosure, the sealing member may have a through hole. In this case, at least a part of the columnar portion may be arranged in the through hole, and the plate-shaped portion may be arranged between the power storage element and the sealing member. In this configuration, the opening (O) can be sealed by the sealing member and the columnar portion. When the internal pressure inside the case rises and the joint breaks, thereby separating the plate-shaped portion and the columnar portion, the columnar portion moves outward in the through hole. When the inside of the case and the outside of the case communicate with each other through the through hole due to the movement of the columnar portion, the substance inside the case is released to the outside of the case.

When a part of the columnar portion is arranged in the through hole of the sealing member, the portion of the through hole of the sealing member where the force of the sealing member to press the columnar portion is maximum is the central axis of the through hole. It may be located closer to the power storage element than the center of the through hole in the direction. According to this configuration, when the joint portion is broken, the columnar portion can easily move in the through hole. In the through hole of the sealing member, the portion where the force of the sealing member to press the columnar portion is maximum is at the same position as the center of the through hole in the direction of the central axis of the through hole, or is a storage element rather than the center. May be on the other side.

The tubular portion of the case may have an annular groove portion protruding from the outer peripheral surface of the tubular portion toward the central axis of the tubular portion. Then, the columnar portion in the through hole may be pressed by the groove portion via the sealing member. In this example, in the columnar portion, the portion pressed by the deepest portion of the groove portion is the portion where the force of the sealing member to press the columnar portion is maximized. In other words, the plane perpendicular to the central axis of the tubular part, where the plane including the deepest part of the groove and the columnar part intersect, the force that the sealing member presses against the columnar part is the maximum. It may be a part of. The intersecting portion may exist on the power storage element side of the center of the through hole in the direction of the central axis of the through hole, or may exist at a position different from that.

The plate-shaped portion of the current collector member (C) may have an insertion hole, and a part of the columnar portion may be inserted into the insertion hole. According to this configuration, the current collector member (C) can be easily formed. Further, according to this configuration, a joint portion (B) that is easily broken is easily formed.

The joint portion (B) may be formed along the peripheral surface of the columnar portion. The joint portion (B) may be formed so that the object does not flow at the portion of the insertion hole when the joint portion (B) is not broken. Alternatively, the joint portion (B) may be formed so that an object can flow through the insertion hole portion even when the joint portion (B) is not broken. For example, the joint portions (B) may be formed so as to be scattered on the peripheral surface of the columnar portion. In either case, the case may be sealed by the sealing member and the current collector (C).

The joint portion (B) may be thinner than the plate-shaped portion. According to this configuration, when the internal pressure in the case rises, it is easy to break at the joint portion (B). However, the thickness of the joint portion (B) is not limited as long as the joint portion (B) breaks when the internal pressure in the case rises to the value of the range X.

The joint portion (B) may be formed on the power storage element side of the center of the plate-shaped portion in the thickness direction of the plate-shaped portion. According to this configuration, when the internal pressure in the case rises, it is easy to break at the joint portion (B). However, as long as the joint portion (B) breaks when the internal pressure in the case rises above a predetermined value, the joint portion (B) may be formed at a position other than the above.

The joint portion (B) may be formed by welding a plate-shaped portion and a columnar portion. The welding method is not particularly limited, and laser welding, arc welding, resistance welding and the like may be used. Alternatively, the plate-shaped portion and the columnar portion may be joined by soldering. In this case, the joint portion (B) is formed of solder. Welding or soldering may be performed by welding or soldering the plate-shaped portion and the columnar portion from the side that is the power storage element side. According to this configuration, it is easy to form a welded portion or a soldered portion on the power storage element side. Alternatively, welding or soldering may be performed by welding or soldering the plate-shaped portion and the columnar portion from the side opposite to the power storage element.

An example of the power storage device according to the present disclosure may satisfy the following configuration (1). Further, at least one of the following configurations (2) to (5) may be satisfied.
(1) The sealing member has a through hole, and at least a part of the columnar portion is arranged in the through hole. The plate-shaped portion is arranged between the power storage element and the sealing member.
(2) The portion of the through hole of the sealing member where the force of the sealing member to press the columnar portion is maximum exists on the power storage element side of the center of the through hole in the direction of the central axis of the through hole.
(3) The plate-shaped portion has an insertion hole into which a part of the columnar portion is inserted. In this case, the joint portion (B) may be provided along the peripheral surface of the columnar portion.
(4) The joint portion (B) is formed on the power storage element side of the center of the plate-shaped portion in the thickness direction of the plate-shaped portion.
(5) The joint portion (B) is formed by welding a plate-shaped portion and a columnar portion.

The power storage device and its components according to the present disclosure will be described below with reference to examples. The power storage device is a device that can be charged and discharged. 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, or the like. The electricity storage device may be an electric double layer capacitor (EDLC) using activated carbon as an electrode material, a lithium ion capacitor (LIC), or another electrolytic capacitor.

(Power storage element)
The power storage element is not particularly limited, and may be selected according to the type of power storage device. A known power storage element may be used as the power storage element. For example, when the power storage device is a secondary battery, a power storage element including a positive electrode, a negative electrode, a separator, and an electrolytic solution may be used. The negative electrode of an example lithium ion secondary battery contains a substance that reversibly occludes and releases lithium ions as a negative electrode active material. The negative electrode active material includes, for example, a carbon material such as graphite and an inorganic compound such as silicon and titanium oxide. The positive electrode of these secondary batteries may contain a transition metal composite oxide containing lithium as a positive electrode active material. This transition metal composite oxide includes elements such as nickel, manganese, cobalt and aluminum.

When the power storage device is a capacitor, the power storage element may include a pair of electrodes, a separator arranged between the electrodes, and an electrolytic solution and a separator. These components can be selected according to the type of capacitor. For example, when the power storage device is an electric double layer capacitor, electrodes containing activated carbon as an active material may be used for the pair of electrodes. When the power storage device is a lithium ion capacitor, an electrode containing activated carbon as an active material may be used for one of the pair of electrodes (positive electrode). In this case, the negative electrode used in the lithium ion secondary battery can be used for the other (negative electrode) of the pair of electrodes. An example of a negative electrode used in a lithium ion secondary battery includes, for example, a negative electrode active material (eg graphite) capable of occluding and releasing lithium ions.

If the power storage device is a capacitor, the power storage element may include a winder. The winding body may be formed by winding the pair of electrodes and the separator so that the separator is arranged between the pair of electrodes. The pair of electrodes may be polar electrodes, one of which may be an anode and the other of which may be a cathode. When the power storage device is a secondary battery, the power storage element includes a group of electrodes. The electrode group may be formed by winding a positive electrode and a negative electrode via a separator. The storage element may further contain an electrolytic solution or a liquid component.

When the power storage device is a capacitor, at least one of the pair of electrodes may contain activated carbon as the active material. In addition to activated carbon, the electrode usually further contains a binder and a conductive agent. The electrode may further include a current collector carrying an active layer.

(Case)
The case may function as an electrode terminal. When the case functions as an electrode terminal, the case is formed using, for example, a conductive metal. In that case, one of the pair of electrodes included in the power storage element is electrically connected to the case. The case may be made of aluminum, iron, copper, or an alloy or clad material of these metals. As the case of the power storage device, a known case of the power storage device may be used.

The case includes a cylindrical portion and a bottom portion that closes one end of the tubular portion, and has an opening at the other end of the tubular portion. The tubular portion may be cylindrical or square tubular, but is typically cylindrical. The tubular portion may have an annular groove portion protruding from the outer peripheral surface of the tubular portion toward the central axis of the tubular portion. The sealing member may be pressed by this groove.

(Current collector (C))
As described above, the current collector member (C) has a plate-shaped portion, a columnar portion, and a joint portion (B) for joining the plate-shaped portion and the columnar portion. The current collector member (C) is formed of a conductive material, for example, a metal. Examples of the material of the current collector (C) include iron, copper, aluminum, and alloys containing them. The material of the current collector member (C) may be selected according to the type of the power storage element. The plate-shaped portion, the columnar portion, and the joint portion (B) may be formed of the same material or may be formed of different materials.

The plate-shaped portion has a shape corresponding to the shape of the tubular portion of the case. For example, when the tubular portion of the case is cylindrical, the plate-shaped portion may have a disk-shaped shape having an insertion hole (through hole) formed in the center.

The thickness of the plate-shaped portion is not particularly limited, but may be in the range of, for example, 0.3 mm to 1 mm (for example, the range of 0.4 mm to 0.8 mm). The thickness of the joint is set to break when the pressure in the case rises to a value within a predetermined range (X). The thickness of the joint portion may be thinner than that of the plate-shaped portion. The thickness of the joint portion may be 5% or more, 10% or more, 20% or more, or 30% or more of the thickness of the plate-shaped portion. Further, the thickness of the joint portion may be 80% or less, 60% or less, 50% or less, less than 50%, or 40% or less of the thickness of the plate-shaped portion. These lower and upper limits can be combined arbitrarily. For example, the thickness of the joint portion may be 5% or more and 80% or less of the thickness of the plate-shaped portion, or 10% or more and less than 50%.

(Sealing member)
The sealing member is made of an elastic and insulating material. The sealing member may be formed of, for example, an insulating resin or an insulating rubber. Examples of resins used as materials for sealing members include polypropylene (PP), polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), perfluoroalkoxy alkane (PFA), polyetheretherketone (PEEK), and the like. Is done. Examples of rubber used as a material for the sealing member include butyl rubber and the like. Additives (eg, known additives) may be added to these materials as needed. The sealing member can be manufactured by a known method.

(Manufacturing method of power storage device)
The method for manufacturing the power storage device is not particularly limited, and the power storage device can be manufactured by using a known method. In the manufacturing method of one example, first, the power storage element is arranged in the case, one electrode of the power storage element and the case are electrically connected, and the other electrode of the power storage element and the current collector member (C) are electrically connected. Connect to the target. Next, the current collector member (C) and the sealing member are arranged at the opening of the case, and the sealing member is crimped at the end of the case on the opening (O) side to seal the case. At this time, if necessary, an annular groove portion is formed in the tubular portion of the case. In this way, the power storage device is manufactured.

Hereinafter, an example of the first and second power storage devices according to the present disclosure will be specifically described with reference to the drawings. The above-mentioned components can be applied to the components of the power storage device described below. Further, the power storage device described below can be changed based on the above description. Further, the matters described below may be applied to the above-described embodiment. Further, in the embodiment described below, components that are not essential for the power storage device of the present disclosure may be omitted. The figure shown below is schematic and does not reflect the actual scale.

(Embodiment 1)

A cross-sectional view of the configuration of the power storage device 100 according to the first embodiment is schematically shown in FIG. The power storage device 100 corresponds to any of the above-mentioned first power storage device and the second power storage device. The power storage device 100 includes a case 10, a power storage element 20, a sealing member 30, and a current collector member (current collector member (C)) 40. The power storage device 100 further includes a current collector plate 51.

The case 10 is made of a conductive metal and functions as an electrode terminal. The case 10 includes a cylindrical portion 10a and a bottom portion 10b that closes an opening at one end of the tubular portion 10a. The case 10 has an opening (opening (O)) 10h at the other end of the tubular portion 10a. The tubular portion 10a has an annular groove portion 10g protruding from the outer peripheral surface of the tubular portion 10a toward the central axis of the tubular portion 10a. A part of the sealing member 30 is crimped by the end portion of the tubular portion 10a on the opening 10h side.

The power storage element 20 is arranged in the case 10. An electrolytic solution (not shown) is arranged in the case 10, and the electrolytic solution constitutes a part of the power storage element 20. The power storage element 20 includes a plate group 21 and ends 22 and 23. The electrode plate group 21 is formed, for example, by winding the pair of electrodes and the separator so that the separator is arranged between the pair of electrodes. The end 22 includes a conductive member (current collector and / or lead) connected to one of the pair of electrodes. The conductive member at the end 22 is electrically connected to the current collector 40 (for example, the plate-shaped portion 41 of the current collector 40) by welding or the like. The end 23 includes a conductive member (current collector and / or lead) connected to the other electrode of the pair of electrodes. The conductive member at the end 23 is connected to the current collector plate 51 having conductivity by welding or the like. The current collector plate 51 is electrically connected to the case 10 (for example, the bottom portion 10b of the case 10). That is, the conductive member at the end 23 is electrically connected to the case 10 via the current collector plate 51.

FIG. 2 schematically shows a top view of the current collector 40 before being incorporated into the power storage device 100 when viewed from the columnar portion 42 side. The current collector member 40 includes a plate-shaped portion 41, a columnar portion 42, and a joint portion (joint portion (B)) 43 for joining the plate-shaped portion 41 and the columnar portion 42. The plate-shaped portion 41, the columnar portion 42, and the joint portion 43 are each made of a conductive material. The plate-shaped portion 41 has a disk-shaped shape having an insertion hole (through hole) 41h in the center. In other words, the plate-shaped portion 41 has a flat donut-shaped shape. The columnar portion 42 has a substantially columnar shape. A part of the columnar portion 42 on one end side is inserted into the insertion hole 41h. A part of the other portion of the columnar portion 42 is inserted into the through hole 30h of the sealing member 30, and the other end of the columnar portion 42 protrudes from the sealing member 30. The diameter of the columnar portion 42 is a diameter that can be inserted into the insertion hole 41h. That is, the diameter of the columnar portion 42 is the same as or slightly smaller than the diameter of the insertion hole 41h.

The joint portion 43 electrically connects the plate-shaped portion 41 and the columnar portion 42. The columnar portion 42 is electrically connected to one of the pair of electrodes of the power storage element 20 via the joint portion 43, the plate-shaped portion 41, and the like. The columnar portion 42 functions as an electrode terminal. The columnar portion 42 of the example shown in FIG. 1 has a tapered shape in which the tip portion on the side opposite to the plate-shaped portion 41 becomes thinner toward the end. By adopting such a tapered shape, it becomes easy to insert the columnar portion 42 into the through hole 30h of the sealing member 30.

In the example shown in FIG. 1, the joint portion 43 is formed in a donut shape along the peripheral surface 42p of the columnar portion 42. For example, the joint portion 43 may be formed so as not to allow a substance to permeate at the portion of the joint portion 43 in a state where the joint portion 43 is not broken. Alternatively, the joints 43 may be formed so as to be scattered. As described above, the joint is formed by welding, soldering, or the like.

FIG. 3 schematically shows a top view of the sealing member 30 before being incorporated into the power storage device 100 when viewed from the opening 10h side. The sealing member 30 has a through hole 30h in the center. An example of the sealing member 30 before being assembled into the power storage device 100 includes a columnar portion having a through hole 30h formed in the center. A part of the columnar portion 42 is inserted into the through hole 30h. The opening 10h of the case 10 is sealed by the sealing member 30 and the columnar portion 42. In the power storage device 100 shown in FIG. 1, the case 10, the sealing member 30, and the columnar portion 42 (current collector member 40) function as an exterior body containing the power storage element 20.

In the state of the power storage device 100, the through hole 30h is hermetically sealed by inserting the columnar portion 42 into the through hole 30h. That is, the diameter of the through hole 30h is set so that such a state is realized. For example, the diameter of the through hole 30h of the sealing member 30 before being incorporated into the power storage device 100 may be the same as or substantially the same as the diameter of the columnar portion 42. Even if the diameter of the through hole 30h is smaller than the diameter of the columnar portion 42, the sealing member 30 has elasticity, so that the columnar portion 42 can be inserted. On the other hand, even if the diameter of the through hole 30h is larger than the diameter of the columnar portion 42, the through hole 30h can be hermetically sealed by pressing the sealing member 30 with the groove portion 10g.

When the internal pressure in the case 10 rises to a value in a predetermined range X (a predetermined value or more), the joint portion 43 breaks. At that time, the diameter of the through hole 30h and / or the depth of the groove portion 10g are set so that the columnar portion 42 can move in the direction away from the power storage element 20.

In the power storage device 100, the temperature of the power storage element 20 may rise excessively due to an abnormality such as a short circuit in the power storage element 20, and the internal pressure in the case 10 may rise excessively. When the internal pressure in the case 10 rises above a predetermined value, the joint portion 43 breaks. As a result, the plate-shaped portion 41 and the columnar portion 42 are separated, and the electrical connection between the plate-shaped portion 41 and the columnar portion 42 is cut off. As shown in FIG. 4, the columnar portion 42 separated from the plate-shaped portion 41 moves in the direction away from the power storage element 20 due to the internal pressure. Finally, as shown in FIG. 5, the columnar portion 42 is extruded to the outside of the through hole 30h. As a result, the inside and the outside of the case 10 communicate with each other at the portion of the through hole 30h. As a result, the substance in the case 10 (for example, gas and / or the electrolytic solution) is released to the outside of the case 10, and the internal pressure in the case 10 decreases. According to this configuration, it is possible to prevent the case 10 from being excessively deformed and torn.

The direction in which the columnar portion 42 separates from the power storage element 20 even if the columnar portion 42 is not completely detached from the through hole 30h due to a change in the shape of the columnar portion 42 and / or a change in the shape of the through hole 30h. It is possible to communicate the inside and the outside of the case 10 at the portion of the through hole 30h by moving to some extent. Examples of such shape changes include the formation of grooves, the formation of steps, and at least a partial change to a tapered shape.

FIG. 6 shows an enlarged cross-sectional view of the vicinity of the current collector member 40. In the following figures, hatching may be omitted for ease of understanding.

FIG. 6 shows the center position LTc of the through hole 30h in the direction Dax of the central axis of the through hole 30h of the sealing member 30. FIG. 6 also shows the length T of the through hole 30h in the direction Dax. The central position LTc is located at a position separated by a length T / 2 from each of both ends of the through hole 30h.

Further, FIG. 6 shows the position of the plane Pmax which is a plane passing through the deepest portion 10 gm of the groove portion 10 g of the case 10 and is perpendicular to the central axis 10 c of the tubular portion 10a. The sealing member 30 is pressed by the groove portion 10g. Therefore, the force with which the sealing member 30 presses the columnar portion 42 becomes maximum at the portion where the plane Pmax and the columnar portion 42 intersect. As shown in FIG. 6, this portion preferably exists on the power storage element 20 side of the center (center position LTc) of the through hole 30h in the direction Dax. According to this configuration, when the joint portion 43 breaks and the plate-shaped portion 41 and the columnar portion 42 are separated, the columnar portion 42 can easily move in the through hole 30h.

FIG. 6 shows the center position Ltc of the plate-shaped portion 41 in the thickness direction Dth of the plate-shaped portion 41. Further, FIG. 6 also shows the thickness t of the plate-shaped portion 41. The central position Ltc is located at a position separated from each of the two main surfaces of the plate-shaped portion 41 by a length t / 2. As shown in FIG. 6, it is preferable that the joint portion 43 is formed on the power storage element 20 side of the central position Ltc. In this case, when the internal pressure in the case 10 rises, as shown in FIG. 7, stress tends to be concentrated on the joint portion 43, and the joint portion 43 tends to break.

As shown in FIG. 8, the joint portion 43 may be formed on the surface of the plate-shaped portion 41 and the columnar portion 42 facing the power storage element 20. Such a joint portion 43 may be formed by, for example, soldering.

The present invention can be used for a power storage device.

10: Case 10a: Cylindrical part 10b: Bottom part 10c: Central shaft 10g: Groove part 10h: Opening part 20: Power storage element 30: Sealing member 30h: Through hole 40: Current collecting member 41: Plate-shaped part 41h: Insertion hole 42 : Columnar portion 42p: Peripheral surface 43: Joint portion 100: Power storage device

Claims (9)

A case including a tubular portion and a bottom portion that closes one end of the tubular portion, and a case having an opening at the other end of the tubular portion.
The storage element arranged in the case and
The sealing member arranged in the opening and
Including a current collector member electrically connected to the power storage element,
The current collecting member includes a plate-shaped portion, a columnar portion, and a joint portion for joining the plate-shaped portion and the columnar portion.
The opening is sealed by the sealing member and the current collecting member.
A power storage device in which a substance in the case is discharged to the outside of the case by breaking the joint when the internal pressure in the case rises and reaches a value in a predetermined range. A case including a tubular portion and a bottom portion that closes one end of the tubular portion, and a case having an opening at the other end of the tubular portion.
The storage element arranged in the case and
The sealing member arranged in the opening and
Including a current collector member electrically connected to the power storage element,
The current collecting member includes a plate-shaped portion, a columnar portion, and a joint portion for joining the plate-shaped portion and the columnar portion.
The opening is sealed by the sealing member and the current collecting member.
A power storage device in which the electrical connection between the plate-shaped portion and the columnar portion is cut off by breaking the joint portion when the internal pressure in the case rises and reaches a value in a predetermined range. The sealing member has a through hole and has a through hole.
At least a part of the columnar portion is arranged in the through hole, and the columnar portion is arranged in the through hole.
The power storage device according to claim 1 or 2, wherein the plate-shaped portion is arranged between the power storage element and the sealing member. The portion of the through hole of the sealing member where the force of the sealing member to press the columnar portion is maximum is located closer to the power storage element than the center of the through hole in the direction of the central axis of the through hole. The power storage device according to claim 3. The plate-shaped portion has an insertion hole and has an insertion hole.
The power storage device according to any one of claims 1 to 4, wherein a part of the columnar portion is inserted into the insertion hole. The power storage device according to claim 5, wherein the joint portion is formed along the peripheral surface of the columnar portion. The power storage device according to any one of claims 1 to 6, wherein the joint portion is thinner than the plate-shaped portion. The power storage device according to any one of claims 1 to 7, wherein the joint portion is formed on the power storage element side with respect to the center of the plate shape portion in the thickness direction of the plate shape portion. The power storage device according to any one of claims 1 to 8, wherein the joint portion is formed by welding the plate-shaped portion and the columnar portion.

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