Electric energy storage device

Abstract

This electricity storage device is provided with an electrode group including a first electrode and a second electrode, a case which accommodates the electrode group and which has an opening, and a sealing body which closes the opening in the case, wherein: the case includes a tube portion, a curved portion continuous with one end portion of the tube portion, and a bottom portion which closes the other end portion of the tube portion; the curved portion includes an opening edge portion, a crimped portion which is continuous with the opening edge portion and is located outside the opening edge portion in the radial direction of the tube portion, and an annular groove portion which is continuous with the crimped portion and which is recessed in such a way as to project inward in the radial direction of the tube portion; the sealing body includes an electrically conductive sealing plate, and an insulating gasket which is compressed between the sealing plate and a region of the crimped portion facing the groove portion, and between the sealing plate and an inner surface of the groove portion; the case and the first electrode are electrically connected to one another; the sealing plate and the second electrode are electrically connected to one another; and the opening edge portion is not in contact with the gasket.

Description

Technical Field

[0001] The present disclosure relates to a power storage device.

Background Art

[0002] Power storage devices are widely used as drive sources for vehicles, electronic devices, etc. Generally, a power storage device includes a case that houses an electrode group including a first electrode and a second electrode and has an opening, and a sealing body that closes the opening of the case. When the first electrode is electrically connected to the case, the second electrode is provided on the sealing body and connected to a terminal portion that is electrically insulated from the case.

[0003] When modularizing a plurality of power storage devices, from the viewpoint of simplifying the current collection structure, it is desirable to arrange a first current collection member electrically connected to the first electrode and a second current collection member electrically connected to the second electrode on the opening side of the power storage device. In that case, it is desirable to weld the first current collection member to the opening edge portion of the case and weld the second current collection member to the terminal portion of the sealing body.

[0004] As shown in Patent Document 1, as a secondary battery, an electrode body, a cylindrical outer can, and a sealing body caulked and fixed to the opening of the outer can via a gasket are provided, and this sealing body is a cylindrical battery caulked and fixed to the gasket, is known.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the case of Patent Document 1, since the opening edge of the case is caulked to the outer periphery of the sealing lid via a gasket, the opening edge is pressed against the gasket and is in close contact with the gasket. In such a structure, if a first current collecting member is welded to the opening edge of the case, the gasket may be deteriorated by the heat of welding. And when the gasket deteriorates, the sealing performance by caulking may decrease.

[0007] An object of the present disclosure is to suppress deterioration of a gasket included in a sealing body of an electric storage device.

Means for Solving the Problems

[0008] One aspect of the present disclosure includes an electrode group including a first electrode and a second electrode, a case that houses the electrode group and has an opening, and a sealing body that closes the opening of the case. The case has a cylindrical portion, a curved portion continuous with one end of the cylindrical portion, and a bottom portion that closes the other end of the cylindrical portion. The curved portion has an opening edge portion, a caulking portion that is continuous with the opening edge portion and is outward in the radial direction of the cylindrical portion from the opening edge portion, and an annular groove portion that is continuous with the caulking portion and is recessed so as to protrude inward in the radial direction of the cylindrical portion. The sealing body has a conductive sealing plate and an insulating gasket that is compressed between the sealing plate and a region facing the groove portion of the caulking portion and between the sealing plate and the inner surface of the groove portion. The case and the first electrode are electrically connected, the sealing plate and the second electrode are electrically connected, and the opening edge portion is not in contact with the gasket, relating to an electric storage device.

Effects of the Invention

[0009] According to the present disclosure, since it is possible to join the current collecting member at a portion of the caulking portion of the case that is not in contact with the gasket, it is possible to provide an electric storage device in which deterioration of the gasket included in the sealing body is suppressed.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 4C

Figure 4D

Figure 4E

Figure 4F

Figure 4G

Figure 4H

Figure 4I

Figure 4J

Embodiments for Carrying Out the Invention

[0011] The power storage device according to one aspect of the present disclosure includes an electrode group including a first electrode and a second electrode, a case that houses the electrode group and has an opening, and a sealing body that closes the opening of the case. The case has a cylindrical portion, a curved portion continuous with one end of the cylindrical portion, and a bottom portion that closes the other end of the cylindrical portion. The curved portion has an opening edge portion, a caulking portion that is continuous with the opening edge portion and is outward in the radial direction of the cylindrical portion from the opening edge portion, and an annular groove portion that is recessed so as to project inward in the radial direction of the cylindrical portion and is continuous with the caulking portion. The sealing body has a conductive sealing plate and an insulating gasket that is compressed between the sealing plate and a region facing the groove portion of the caulking portion and between the sealing plate and the inner surface of the groove portion. The case is electrically connected to the first electrode. The sealing plate is electrically connected to the second electrode, and the opening edge portion is not in contact with the gasket. The case may be made of, for example, metal. The metal constituting the case may be made of aluminum, copper, iron, stainless steel, nickel, or an alloy combining these metals.

[0012] Since the opening edge portion is not in contact with the gasket, even when a first current collector member is welded to the opening edge portion, heat from the welding is less likely to be transmitted to the gasket, so deterioration of the gasket is suppressed. For example, a first current collecting lead having the same polarity as the first electrode and derived from the first current collector member is welded to the outer surface of the opening edge portion. On the other hand, a second current collecting lead having the same polarity as the second electrode and derived from the second current collector member is welded to the outer surface of the sealing plate. Examples of the material of the gasket include polypropylene (PP), polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), perfluoroalkoxy alkane (PFA), and polyether ether ketone (PEEK).

[0013] At the boundary between the opening edge and the caulked portion, a step may be formed such that the distance D1 between the opening edge and the groove portion in the axial direction of the cylindrical portion is greater than the distance D2 between the caulked portion and the groove portion in the axial direction. Here, the distance D1 is the shortest distance between the opening edge and the groove portion in the axial direction, and the distance D2 is the shortest distance between the caulked portion and the groove portion in the axial direction. The height of the groove portion serving as the reference for D1 and D2 is the height of the deepest part of the groove portion (the part closest to the axis of the cylindrical portion). By making D1 > D2, the heat of welding is less likely to be further transmitted to the gasket, so the deterioration of the gasket is further suppressed.

[0014] In order to easily make D1 > D2, the curved portion may have a first curved portion facing the side opposite to the bending direction of the caulked portion at the boundary between the opening edge and the caulked portion. Such a first curved portion can be easily formed in the case before forming the caulked portion. The gasket is most compressed by the first curved portion. In other words, by forming the first curved portion, it becomes easier to increase the compression rate of the gasket by the caulked portion. In the power storage device of the present disclosure, the first curved portion does not necessarily compress the gasket most strongly. A flat portion may be formed in the caulked portion, and this flat portion may compress the gasket most strongly. In the radial direction of the power storage device, an inclined surface that descends more toward the outside may compress the gasket most strongly.

[0015] Between the first curved portion and the outermost end of the opening edge, a second curved portion facing the same side as the bending direction of the caulked portion may be provided. By providing the second curved portion, the outermost end of the opening edge does not protrude excessively in the direction away from the sealing body in the axial direction of the cylindrical portion. Also, by controlling the magnitude of the inner angle of the second curved portion, the angle formed by the opening edge and the radial direction of the cylindrical portion can be made closer to 0°. That is, a flat portion along the radial direction of the cylindrical portion can be provided at the opening edge. Such a flat portion facilitates welding with the first current collector member. On the outer surface of the flat portion of the opening edge, a first current collecting lead derived from the first current collector member and having the same polarity as the first electrode can be easily welded.

[0016] At least a part of the opening edge portion may have a thin-walled portion thinner than the caulked portion. A notch defined including the thin-walled portion may be formed on the surface of the curved portion facing the gasket. Even with this configuration, a gap is formed between the thin-walled portion and the gasket in the same manner as when the opening edge portion is bent from the caulked portion. This gap suppresses the transfer of heat generated when the thin-walled portion is joined to the current collecting member to the gasket. Further, if the thin-walled portion is formed, a gap can be formed between the gasket and the opening edge portion without bending the caulked portion or the opening edge portion outward of the case. Therefore, an increase in the dimension in the height direction as the power storage device can be suppressed. Note that all of the opening edge portion may be a thin-walled portion thinner than the caulked portion, or a part of the opening edge portion may be a thin-walled portion. In the curved portion, a step may be formed on the inner surface (the surface facing the gasket) of the thin-walled portion of the caulked portion or the opening edge portion, or an inclined surface may be formed.

[0017] Note that the type of the power storage device is not particularly limited, and examples thereof include a primary battery, a secondary battery, a lithium ion capacitor, an electric double layer capacitor, and a solid electrolytic capacitor. Among them, a non-aqueous electrolyte secondary battery (including an all-solid battery) such as a lithium ion secondary battery having a high energy density can be preferably used.

[0018] Hereinafter, the power storage device according to the embodiment of the present invention will be specifically described with reference to the drawings, but the present invention is not limited thereto.

[0019] FIG. 1 is a cross-sectional view showing an example of the structure of a power storage device 100 according to an embodiment. FIG. 2 is a cross-sectional view showing the structure of the case of the power storage device of FIG. 1 before processing. The power storage device 100 includes an electrode group 120 including a first electrode and a second electrode, a case 110 that houses the electrode group 120 and has an opening 101, and a sealing body 130 that closes the opening 101 of the case 110. The case 110 has a cylindrical tube portion 111, a curved portion 112 continuous with one end of the tube portion 111, and a bottom portion 113 that closes the other end of the tube portion 111.

[0020] The bent portion 112 has an opening edge portion 1121, a caulking portion 1122 that is continuous with the opening edge portion 1121 and is outward in the radial direction of the cylindrical portion 111 from the opening edge portion 1121, and an annular groove portion 1123 that is continuous with the caulking portion 1122 and is recessed so as to protrude inward in the radial direction of the cylindrical portion 111.

[0021] The sealing body 130 has a conductive sealing plate 131 and an insulating gasket 133. The gasket 133 is compressed between the region facing the groove portion 1123 of the caulking portion 1122 and the sealing plate 131, and between the sealing plate 131 and the inner surface of the groove portion 1123.

[0022] The case 110 is electrically connected to the first electrode. The sealing plate 131 is electrically connected to the second electrode. The opening edge portion 1121 does not contact the gasket 133, and a space is provided between the opening edge portion 1121 and the gasket 133 so that heat applied to the opening edge portion 1121 does not easily transfer to the gasket 133.

[0023] An internal insulating plate 140 is disposed between the electrode group 120 and the sealing body 130, and the internal insulating plate 140 prevents contact between the electrode group 120 and the sealing body 130. A predetermined lead hole 141 is provided in the internal insulating plate 140. The first electrode constituting the electrode group 120 is electrically connected to the case 110. Therefore, the case 110 has the same polarity as the first electrode. The lead 122 led out from the second electrode passes through the lead hole 141 and is electrically connected to the inner surface of the sealing plate 131. Therefore, the sealing plate 131 has the same polarity as the second electrode.

[0024] On the outer surface of the opening edge portion 1121, a first current collecting lead 301 that is led out from the first current collecting member and has the same polarity as the first electrode is welded. On the other hand, on the outer surface of the sealing plate 131, a second current collecting lead 401 that is led out from the second current collecting member and has the same polarity as the second electrode is welded.

[0025] FIG. 3 is a diagram for explaining the influence of heat applied to the gasket 133 included in the sealing body 130. As shown in FIG. 3(a), when the opening edge portion 1121 is not distinguished from the caulked portion 1122 and is in contact with the gasket 133, the heat applied to the opening edge portion 1121 directly transfers to the most compressed and loaded portion of the gasket 133, deteriorating the gasket 133. On the other hand, as shown in FIG. 3(b), when the opening edge portion 1121 is distinguished from the caulked portion 1122 and is not in contact with the gasket 133, the heat applied to the opening edge portion 1121 is less likely to transfer to the gasket 133, suppressing the deterioration of the gasket 133.

[0026] At the boundary between the opening edge portion 1121 and the caulked portion 1122, a step is formed such that the distance D1 between the opening edge portion 1121 and the groove portion 1123 in the axial direction of the cylindrical portion 111 is larger than the distance D2 between the caulked portion 1122 and the groove portion 1123 in the axial direction. The distance D1 is the shortest distance between the inner surface of the opening edge portion 1121 and the groove portion 1123 in the axial direction, and the distance D2 is the shortest distance between the inner surface of the caulked portion 1122 and the groove portion 1123 in the axial direction. The height of the groove portion serving as the reference for D1 and D2 is the height of the deepest part of the groove portion, which is closest to the axis of the cylindrical portion (indicated by point P in FIG. 1).

[0027] The curved portion 112 has a first bent portion 112A that faces the side opposite to the bending direction of the caulked portion 1122 at the boundary between the opening edge portion 1121 and the caulked portion 1122. The gasket 133 is most compressed by the first bent portion 112A.

[0028] Further, the curved portion 112 has a second bent portion 112B that faces the same side as the bending direction of the caulked portion 1122 between the first bent portion 112A and the outermost end portion 1121T of the opening edge portion 1121. By providing the second bent portion 112B, the outermost end portion 1121T of the opening edge portion 1121 does not protrude excessively in the direction away from the sealing body 130 in the axial direction of the cylindrical portion 111. The angle formed between the opening edge portion 1121 and the radial direction (horizontal direction perpendicular to the axial direction) of the cylindrical portion 111 is approximately 0°, facilitating the welding of the first current collecting lead 301 to the opening edge portion 1121.

[0029] At least a part of the opening edge portion 1121 may have a thin portion thinner than the caulking portion 1122. A notch defined including the thin portion may be formed in the surface of the curved portion 112 facing the gasket 133.

[0030] Next, a method for manufacturing the power storage device according to the present embodiment will be described. FIGS. 4A to 4J show the first to tenth steps of the manufacturing process of the power storage device. In each figure, for ease of understanding, the case 110, the sealing plate 131, the gasket 133, and the outer shape of a predetermined mold are shown, and the illustration of other elements is omitted in principle.

[0031] <Step 1> First, a power storage element group 120, a precursor of the case 110 (case precursor 110X), and a sealing body 130 are prepared. The power storage element group 120 is housed in the case precursor 110X, the internal insulating plate 140 is disposed, a lead (not shown) led out from the first electrode is electrically connected to the case 110, and the lead 122 led out from the second electrode is electrically connected to the inner surface of the sealing plate 131 (FIG. 4A). Thereafter, an annular groove portion 1123 is formed at a position slightly closer to the opening 101 side than the internal insulating plate 140 in the case precursor 110X.

[0032] The case precursor 110X has a cylindrical tube portion 111, a curved portion 112 continuous with one end of the tube portion 111, and a bottom portion 113 closing the other end of the tube portion 111 (see FIG. 2). The curved portion 112 has an opening edge portion 1121, a caulking region 1122X continuous with the opening edge portion 1121, and an annular groove portion 1123 continuous with the caulking region 1122X. The opening edge portion 1121 has a first bent portion 112A that expands the opening 101 radially outward of the tube portion 111 and a second bent portion 112B that returns the opening 101 radially inward of the tube portion 111.

[0033] The sealing body 130 has a sealing plate 131 and a gasket 133. The sealing plate 131 is a disk-shaped member. The gasket 133 is a cylindrical shape having a cylindrical wall portion 1331 and an inner flange-shaped annular base portion 1332 that supports the inner surface of the peripheral edge portion of the sealing plate 131.

[0034] <Second Step> Next, the first mold 510 having an annular protrusion 511 on its inner peripheral surface is fitted into the groove portion 1123 from the outer side in the radial direction of the cylindrical portion 111. Also, the annular second mold 520 is pressed against the outer surface of the sealing plate 131 and pressed in the axial direction of the cylindrical portion 111 (FIG. 4B). Thereby, the sealing body 130 is supported by the groove portion 1123.

[0035] <Third Step> Next, the third mold 530, which is a rotating body, is brought into contact with the outer surface of the opening edge portion 1121 (FIG. 4C). On the peripheral surface of the third mold 530, a plurality of tapered surfaces are provided so that the diameter gradually decreases from the opening 101 side of the case toward the bottom portion 113 side in the axial direction of the cylindrical portion 111.

[0036] <Fourth Step> Next, while rotating the third mold 530, it is pushed into the opening edge portion 1121 from the outer side to the inner side in the radial direction, and the opening edge portion 1121 is bent inward (FIG. 4D).

[0037] <Fifth Step> Next, an annular fourth mold 540 is brought into contact with the caulking region 1122X (FIG. 4E). The caulking region 1122X is a region that intervenes between the first bent portion 112A and the groove portion 1123 in the curved portion 112 and becomes the caulking portion 1122. The fourth mold 540 has a cylindrical concave surface that contacts the caulking region 1122X. The inner diameter of the concave surface becomes smaller as it approaches the contact portion with the vicinity of the first bent portion 112A. Between the concave surface and the annular protrusion 511 of the first mold 510, the caulking region 1122X, the peripheral edge portion of the sealing plate 131, and the gasket 133 are arranged.

[0038] <Sixth Step> Next, the fourth mold 540 is pressed against the outer surface of the caulking region 1122X, and the caulking region 1122X is pressed together with the gasket 133 in the axial direction of the cylindrical portion 111 between the fourth mold 540 and the annular protrusion 511 of the first mold 510 (FIG. 4F).

[0039] <Seventh Step> Next, a fifth mold 550 having a concave surface with a smaller radius of curvature than the concave surface of the fourth mold 540 is prepared. The radius of curvature defined here refers to the minimum radius of curvature of the concave surface obtained when the mold is cut by a plane including the axis of the cylindrical portion (FIG. 4G).

[0040] <Eighth step> Next, the fifth mold 550 is strongly pressed against the outer surface of the caulking region 1122X, and the caulking region 1122X is further pressed axially together with the gasket 133 between the fifth mold 550 and the annular protrusion 511 of the first mold 510 (FIG. 4H).

[0041] The concave surface of the fifth mold 550 presses the caulking region 1122X axially, but only contacts the opening edge portion 1121 to the extent of touching. Almost no stress is applied to the opening edge portion 1121. On the other hand, the caulking region 1122X strongly compresses the gasket 133 under the pressing force from the concave surface of the fifth mold 550. Specifically, the gasket 133 is compressed between the sealing plate 131 and the caulking portion 1122 (particularly the region facing the groove portion 1123 of the caulking portion 1122), and between the sealing plate 131 and the inner surface of the groove portion 1123. The first bent portion 112A bites into the gasket 133.

[0042] <Ninth step> Next, the first mold 510 is retracted from the groove portion 1123, and the peripheral surface of the cylindrical portion 111 is fixed by a cylindrical sixth mold 560 having an inner peripheral surface facing the peripheral surface of the cylindrical portion 111. Then, the pressing surface of the annular seventh mold 570 is brought into contact with the caulking portion 1122 formed by the previous processing from the axial direction (FIG. 4I).

[0043] <Tenth step> Next, the caulking portion 1122 is further strongly pressed axially by the seventh mold 570 (FIG. 4J). As a result, the groove portion 1123 is compressed axially, and the sealing performance of the caulking portion 1122 is enhanced.

[0044] In the above description, a cylindrical power storage device has been described as an example, but the present disclosure can also be applied to power storage devices having various shapes (for example, rectangular).

Industrial Applicability

[0045] The power storage device according to the present disclosure is particularly suitable for use as a power source for vehicles such as hybrid vehicles and electric vehicles.

Explanation of Signs

[0046] 100: Power storage device 101: Opening 110: Case 110X: Precursor of the case 111: Cylindrical part 112: Curved part 1121: Opening edge part 1121T: Outermost end part 1122: Crimping part 1122X: Crimping region 1123: Groove part 112A: First bending part 112B: Second bending part 113: Bottom part 120: Electrode group 122: Lead 130: Sealing body 131: Sealing plate 133: Gasket 140: Internal insulating plate 141: Lead hole 301: First current collecting lead 401: Second current collecting lead 510: First mold 511: Annular protrusion 520: Second mold 530: Third mold 540: Fourth mold 550: Fifth mold 560: Sixth mold 570: Seventh mold

Claims

1. An electrode group including a first electrode and a second electrode; A case that houses the electrode group and has an opening; A sealing body that closes the opening of the case; A first current collecting lead having the same polarity as the first electrode, and comprising: The case has a cylindrical portion, a curved portion continuous with one end of the cylindrical portion, and a bottom portion that closes the other end of the cylindrical portion. The curved portion has an opening edge portion, a caulked portion that is continuous with the opening edge portion and is outward in the radial direction of the cylindrical portion from the opening edge portion, and an annular groove portion that is continuous with the caulked portion and is recessed so as to protrude inward in the radial direction of the cylindrical portion. The sealing body is A conductive sealing plate; An insulating gasket that is compressed between the sealing plate and the region facing the groove portion of the caulked portion, and between the sealing plate and the inner surface of the groove portion. The case and the first electrode are electrically connected; The sealing plate and the second electrode are electrically connected; The opening edge portion is not in contact with the gasket; The first current collecting lead is welded to the outer surface of the opening edge portion; The curved portion is A first bent portion that faces the side opposite to the bending direction of the caulked portion at the boundary between the opening edge portion and the caulked portion; A second bent portion that faces the same side as the bending direction of the caulked portion between the first bent portion and the outermost end portion of the opening edge portion. A power storage device having

2. At the boundary between the opening edge portion and the caulked portion of the curved portion, a step is formed such that a distance D1 between the opening edge portion and the groove portion in the axial direction of the cylindrical portion is larger than a distance D2 between the caulked portion and the groove portion in the axial direction. The power storage device according to claim 1. The power storage device according to claim 1.

3. A second current collecting lead having the same polarity as the second electrode is welded to the outer surface of the sealing plate. The power storage device according to claim 1 or 2.

4. At least a part of the opening edge portion has a thin-walled portion that is thinner than the caulked portion; A notch defined including the thin-walled portion is formed on the surface of the curved portion facing the gasket. The power storage device according to any one of claims 1 to 3. The power storage device according to any one of claims 1 to 3.

5. An electrode group including a first electrode and a second electrode; A case that houses the electrode group and has an opening; A sealing body that closes the opening of the case; A first current collecting lead having the same polarity as the first electrode, and comprising: The case has a cylindrical portion, a curved portion continuous with one end of the cylindrical portion, and a bottom portion that closes the other end of the cylindrical portion. The curved portion has an opening edge portion, a caulking portion that is continuous with the opening edge portion and is outward in the radial direction of the cylindrical portion from the opening edge portion, and an annular groove portion that is continuous with the caulking portion and is recessed so as to protrude inward in the radial direction of the cylindrical portion. The sealing body is a sealing plate having conductivity, and an insulating gasket that is compressed between the sealing plate and a region facing the groove portion of the caulking portion, and between the sealing plate and the inner surface of the groove portion. The case and the first electrode are electrically connected. The sealing plate and the second electrode are electrically connected. The opening edge portion is not in contact with the gasket. The first current collecting lead is welded to the outer surface of the opening edge portion. At least a part of the opening edge portion has a thin-walled portion that is thinner than the caulking portion. A power storage device in which a notch defined including the thin-walled portion is formed in a surface of the curved portion facing the gasket.

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