Electricity storage device and electricity storage module

Abstract

To provide a power storage device capable of reducing the resistance.SOLUTION: A power storage device 1 includes a wound body 2, a case 3, and a current collector plate 4. The wound body 2 includes a first electrode 21 and a second electrode 22 wound around a winding axis X, and the first electrode 21 is exposed at a first winding end 24 located at one end in a direction of the winding axis X. The case 3 has a cylindrical shape with a bottom 30 to store the wound body 2. The current collector plate 4 is located between the first winding end 24 and the bottom 30. In the first winding end 24, the first electrode 21 and the current collector plate 4 are welded in a first welded part 41. The current collector plate 4 and the bottom 30 are welded in a second welded part 34 different from the first welded part 41. The total area of the second welded part 34 is smaller than the total area of the first welded part 41. The bottom 30 has a groove 350 capable of cleaving. The current collector plate 4 is provided with a through hole 40. A position of the groove 350 and a position of the through hole 40 overlap when viewed from the winding axis X direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure generally relates to an electricity storage device and an electricity storage module, and more particularly to an electricity storage device in which a wound body is housed in a case, and an electricity storage module including a plurality of such electricity storage devices. [Background technology]

[0002] Conventionally, there has been known an electric storage device in which a wound body including wound positive and negative electrode members is housed in a case. Examples of such an electric storage device include secondary batteries such as lithium ion batteries (LIBs), lithium ion capacitors (LICs), and electrochemical devices such as electric double-layer capacitors (EDLCs).

[0003] For example, Patent Document 1 describes an electricity storage device in which an electrode group including a wound positive electrode, a negative electrode, and a separator is housed in a bottomed case together with a nonaqueous electrolyte. In the electricity storage device of Patent Document 1, a rod-shaped lead tab is connected to each of the positive electrode and the negative electrode. For example, Patent Document 2 describes a capacitor element including a wound first electrode, a second electrode, and a separator housed in a bottomed cylindrical case together with an electrolyte. Patent Document 2 also describes connecting a first electrode exposed on one end surface of the capacitor element to the inner surface of the case by laser welding from the outer surface of the case. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2017 / 130855 [Patent Document 2] International Publication No. 2007 / 069538 Summary of the Invention [Problem to be solved by the invention]

[0005] In the electricity storage device described in Patent Document 1, power is exchanged only via lead tabs, but the area (current collection area) where the lead tabs are connected to the positive electrode (or negative electrode) is small, so the resistance value of the electricity storage device tends to be high. Also, with the connection method in Patent Document 2, the current collection area between the inner surface of the case and the electrodes can be secured and resistance can be reduced, but it is difficult to connect the inner surface of the case and the electrodes when the electrodes are housed in the case.

[0006] An object of the present disclosure is to provide a low-resistance electricity storage device and an electricity storage module including the same. [Means for solving the problem]

[0007] An electricity storage device according to one aspect of the present disclosure includes a wound body, a case, and a current collector plate. The wound body includes a first electrode and a second electrode wound around a winding axis, with the first electrode exposed at a first winding end located at one end of the winding axis. The case houses the wound body and is cylindrical with a bottom. The current collector plate is located between the first winding end and the bottom. At the first winding end, the first electrode and the current collector plate are welded at a first weld. The current collector plate and the bottom are welded at a second weld different from the first weld. The total area of ​​the second weld is smaller than the total area of ​​the first weld. The bottom has a cleavable groove. The current collector plate has a through hole. When viewed from the winding axis direction, the position of the groove and the position of the through hole overlap. An electricity storage device according to one aspect of the present disclosure includes a wound body, a case, and a current collector plate. The wound body includes a first electrode and a second electrode wound around a winding axis, with the first electrode exposed at a first winding end located at one end of the winding axis direction. The case houses the wound body and is cylindrical with a bottom. The current collector plate is located between the first winding end and the bottom. The first electrode and the current collector plate are electrically and mechanically connected at the first winding end. The current collector plate and the bottom are electrically connected. The bottom has a cleavable groove. The current collector plate has a through hole provided at a position overlapping the winding axis. When viewed from the winding axis direction, the position of the groove and the position of the through hole overlap. An electricity storage device according to one aspect of the present disclosure includes a wound body, a case, and a current collector plate. The wound body includes a first electrode and a second electrode wound around a winding axis, with the first electrode exposed at a first winding end located at one end of the winding axis direction. The case houses the wound body and is cylindrical with a bottom. The current collector plate is located between the first winding end and the bottom. The first electrode and the current collector plate are electrically and mechanically connected at the first winding end. The current collector plate and the bottom are electrically connected. The bottom has an opening whose thickness is smaller than the thickness of its surroundings. The opening has a cleavable groove. The current collector plate has a through hole. When viewed from the winding axis direction, the position of the groove and the position of the through hole overlap. An electricity storage device according to one aspect of the present disclosure includes a wound body, a case, and a current collector plate. The wound body includes a first electrode and a second electrode wound around a winding axis, with the first electrode exposed at a first winding end located at one end of the winding axis. The case houses the wound body and is cylindrical with a bottom. The current collector plate is located between the first winding end and the bottom. The first electrode and the current collector plate are electrically and mechanically connected at the first winding end. The current collector plate and the bottom are electrically connected. The bottom has an opening whose thickness is smaller than the thickness of its surroundings. The opening has a cleavable groove. The current collector plate has a through hole provided at a position overlapping the winding axis. When viewed from the winding axis direction, the position of the groove and the position of the through hole overlap.

[0008] An energy storage module according to one aspect of the present disclosure includes a plurality of the energy storage devices, and the plurality of energy storage devices are electrically and mechanically connected by a conductive member having electrical conductivity. [Effects of the Invention]

[0009] The present disclosure has an advantage in that the resistance of the electricity storage device and electricity storage module can be reduced. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an electricity storage device according to an embodiment of the present disclosure. [Figure 2] Fig. 2A is a schematic perspective view showing the configuration of a wound body included in the above electricity storage device, and Fig. 2B is a schematic bottom view of the wound body shown in Fig. 2A. [Figure 3] FIG. 3 is a schematic plan view showing a current collector plate included in the electricity storage device. [Figure 4] Fig. 4A is a schematic enlarged cross-sectional view of a portion of the electricity storage device, Fig. 4B is a schematic bottom view of the electricity storage device shown in Fig. 4A, and Fig. 4C is an explanatory view showing how grooves in the electricity storage device shown in Fig. 4A are cleaved. [Figure 5]Fig. 5A is a schematic cross-sectional view showing an energy storage module according to an embodiment of the present disclosure, and Fig. 5B is a schematic bottom view of the energy storage module shown in Fig. 5A. [Figure 6] FIG. 6 is a schematic plan view showing a current collector plate included in a power storage module according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0011] 1. Overview As shown in FIGS. 1 and 2A , an electricity storage device 1 according to this embodiment includes a wound body 2, a case 3, and a current collector plate 4. The wound body 2 includes a first electrode 21 and a second electrode 22 wound around a winding axis X, with the first electrode 21 exposed at a first winding end 24 located at one end in the direction of the winding axis X. The case 3 houses the wound body 2 and is cylindrical and has a bottom 30. The current collector plate 4 is electrically and mechanically connected to the first electrode 21 at the first winding end 24, and is located between the first winding end 24 and the bottom 30.

[0012] In the electricity storage device 1 of this embodiment, power is exchanged via the current collector 4, which is electrically connected to the first electrode 21. By electrically connecting the first electrode 21, which is exposed at the first winding end 24, to the current collector 4, the current collection area can be made larger than when the first electrode 21 is electrically connected to a rod-shaped lead tab. In this embodiment, by increasing the current collection area between the first electrode 21 and the current collector 4, the resistance of the electricity storage device 1 can be reduced. Furthermore, because the wound body 2 connected to the current collector 4 is housed in the case 3, connection is easier than when the case 3 and the wound body 2 are directly connected.

[0013] 2.Details Hereinafter, an electricity storage device 1 according to this embodiment and an electricity storage module including the electricity storage device 1 will be described in detail with reference to Fig. 1 to Fig. 5. As described above, the electricity storage device 1 includes the wound body 2, the case 3, and the current collector plate 4.

[0014] 2-1. Wound body As shown in FIG. 2A, the wound body 2 includes a first electrode 21, a second electrode 22, and a separator 23.

[0015] The first electrode 21 is, for example, a conductive sheet material. Examples of the sheet material include metal foil, porous metal, and punched metal. The thickness of the sheet material is not particularly limited as long as the first electrode 21 can be rolled up. Therefore, the first electrode 21 may be in the form of a plate or a film. Examples of the material of the first electrode 21 include copper, copper alloy, nickel, and stainless steel. The first electrode 21 is, for example, copper foil.

[0016] The first electrode 21 of this embodiment has a positive electrode material layer 210 supported on both sides thereof. The positive electrode material layer contains a positive electrode active material. The positive electrode active material has a fibrous or granular inner core portion containing a conductive polymer and a fibrous or granular surface layer portion covering at least a portion of the inner core portion.

[0017] 2A, it is preferable that the first electrode 21 does not carry the positive electrode material layer 210 near the first winding end 24 of the first electrode 21. This allows the first electrode 21 to be exposed at the first winding end 24.

[0018] The second electrode 22 is, for example, a conductive sheet material. Examples of the sheet material include metal foil, porous metal, and punched metal. The thickness of the sheet material is not particularly limited as long as it can roll up the second electrode 22. Therefore, the second electrode 22 may be in the form of a plate or a film. Examples of the material of the second electrode 22 include aluminum, aluminum alloy, nickel, and titanium. The second electrode 22 is, for example, aluminum foil.

[0019] In this embodiment, the second electrode 22 has a negative electrode material layer 220 supported on its surface. The negative electrode material layer 220 includes a negative electrode active material. The negative electrode active material is, for example, a material in which an oxidation-reduction reaction involving the absorption and desorption of lithium ions proceeds. Specific examples of the negative electrode active material include carbon materials, metal compounds, alloys, and ceramic materials. In this embodiment, the second electrode 22 does not support the negative electrode material layer 220 near the second winding end 25 located at the other end of the wound body 2 in the direction of the winding axis X. This allows the second electrode 22 to be exposed at the second winding end 25.

[0020] The separator 23 is, for example, a nonwoven fabric made of cellulose fiber, a nonwoven fabric made of glass fiber, or a microporous membrane, woven fabric, or nonwoven fabric made of polyolefin. The separator 23 of this embodiment includes a first separator 230 and a second separator 231. The first separator 230 and the second separator 231 may be made of the same material or different materials.

[0021] In the wound body 2 of this embodiment, the first electrode 21, the first separator 230, the second electrode 22, and the second separator 231 are stacked in this order and wound around the winding axis X. The first electrode 21, the first separator 230, the second electrode 22, and the second separator 231 may be wound only once, but preferably they are wound two or more times. In this embodiment, the second electrode 22, the first separator 230, the first electrode 21, and the second separator 231 are wound in a cylindrical shape, and the wound body 2 is cylindrical, but is not limited to this. For example, the second electrode 22, the first separator 230, the first electrode 21, and the second separator 231 may be wound in a rectangular shape around the winding axis X, and the wound body 2 may be rectangular. The winding axis X is a virtual central axis when the first electrode 21, the first separator 230, the second electrode 22, and the second separator 231 are wound.

[0022] In this embodiment, as shown in Fig. 2A, a second separator 231 is provided on the outer peripheral surface 26 of the wound body 2. As shown in Fig. 2B, the first electrode 21 is exposed at a first winding end 24 located at one end in the direction of the winding axis X, and multiple layers of the first electrode 21 are formed. The second electrode 22 is exposed at a second winding end 25 located at the other end in the direction of the winding axis X. A terminal board 27, which will be described later, is electrically connected to the second electrode 22.

[0023] 2-2. Current collector plate The current collector plate 4 is a conductive plate-like member. The current collector plate 4 is made of, for example, metal. Examples of materials for the current collector plate include aluminum, copper, nickel, iron, and stainless steel. The thickness of the current collector plate 4 is preferably, for example, within a range of 0.3 mm to 0.5 mm, and more preferably within a range of 0.35 mm to 0.45 mm. In this case, the current collector plate 4 can be made to have both strength and processability.

[0024] The shape of the current collector 4 in a plan view is designed according to the shape of the first winding end 24 in a plan view. In this embodiment, since the shape of the first winding end 24 in a plan view is circular, the shape of the current collector 4 in a plan view is also preferably circular (see FIG. 3 ). The surface area of ​​the current collector 4 is preferably the same as or larger than the surface area of ​​the first winding end 24. In this case, the first electrode 21 on the surface of the first winding end 24 and the current collector 4 can be easily electrically and mechanically connected. Furthermore, as described below, when the current collector 4 is welded to the bottom 30 of the case 3, the area over which the current collector 4 is connected to the bottom 30 can be increased. The current collector 4 is electrically and mechanically connected to the first electrode 21 exposed at the first winding end 24. Examples of methods for connecting the current collector 4 to the first electrode 21 include soldering, brazing using silver paste, and laser welding. In this embodiment, the current collector plate 4 and the first electrode 21 are preferably connected by laser welding.

[0025] In this embodiment, the first electrode 21 and the current collecting plate 4 are electrically and mechanically connected at a first weld 41 at the first winding end 24. If the current collecting plate 4 and the first electrode 21 are connected by laser welding, the first weld 41 corresponds to a weld mark left by the laser welding. In FIG. 3, multiple layers of the first electrode 21 are indicated by dotted lines. In this embodiment, as shown in FIG. 3, the first weld 41 preferably extends linearly across the multiple layers of the first electrode 21 when viewed from one side in the direction of the winding axis X. In other words, the first weld 41 preferably extends linearly from the outer periphery to the center (or from the center to the outer periphery) of the first winding end 24 when viewed from one side in the direction of the winding axis X. In this case, the number of locations where the current collecting plate 4 and the first electrode 21 are welded can be increased, and the area where the current collecting plate 4 and the first electrode 21 are connected (current collecting area) can be increased. This allows the resistance value of the electricity storage device 1 to be reduced. Furthermore, the current collector plate 4 and the first electrode 21 can be mechanically connected firmly. That is, the welding strength between the current collector plate 4 and the first electrode 21 can be improved. Furthermore, because the first weld 41 extends linearly across multiple layers of the first electrode 21, the current collector plate 4 and the first electrode 21 can be welded more easily than if the current collector plate 4 and the first electrode 21 were welded along the multiple layers of the first electrode 21. Furthermore, it is preferable that multiple first welds 41 be provided on the current collector plate 4. In this case, the area over which the current collector plate 4 and the first electrode 21 are connected (current collection area) can be increased, thereby enabling the current collector plate 4 and the first electrode 21 to be mechanically connected more firmly and further reducing the resistance of the electricity storage device 1. The number of first welds 41 on the current collector plate 4 is not particularly limited, but the current collector plate 4 of this embodiment has three first welds 41, as shown in FIG. 3 .

[0026] The current collecting plate 4 of this embodiment is provided with a through hole 40. When gas is generated within the electricity storage device 1 as a result of repeated charging and discharging of the electricity storage device 1, this gas can be guided to the through hole 40. The diameter of the through hole 40 is preferably within a range of 1 mm to 10 mm. In this case, gas generated within the electricity storage device 1 can be easily guided to the through hole 40. The position of the through hole 40 is not particularly limited, but it is preferably provided at the center of the current collecting plate 4 in a plan view. The through hole 40 is preferably provided in a portion of the current collecting plate 4 where the first welded portion 41 is not provided. In other words, the first welded portion 41 is preferably provided in a portion of the current collecting plate 4 where the through hole 40 is not provided.

[0027] In this embodiment, the current collector plate 4 has a notch 42 formed on its outer periphery. When inserting the wound body 2 and the current collector plate 4 into the case 3 described below, the notch 42 makes it possible to determine the orientation of the current collector plate 4 within the case 3. This makes it easy to determine the orientation of the first welded portion 41 within the case 3. The shape of the notch 42 is not particularly limited, and may be semicircular, triangular, rectangular, or linear as shown in FIG. 3 .

[0028] 2-3.Case As shown in FIG. 4A , the case 3 is cylindrical and has a bottom. Specifically, the case 3 includes a bottom 30 and a sidewall 31 that rises from the bottom 30 along the direction of the winding axis X. The thickness of the bottom 30 is not particularly limited. The thickness of the bottom 30 may be constant or may vary partially. Examples of materials for the case 3 include aluminum, nickel, iron, stainless steel, etc. Aluminum is preferred as the material for the case 3 to ensure conductivity and processability. The shape and size of the case 3 are not particularly limited as long as it can accommodate the wound body 2 and the current collector plate 4. When the wound body 2 and the current collector plate 4 are housed in the case 3, the current collector plate 4 is located between the first winding end 24 of the wound body 2 and the bottom 30.

[0029] In this embodiment, it is preferable that the current collecting plate 4 and the bottom portion 30 are electrically connected. The current collecting plate 4 is electrically connected to the first electrode 21 of the wound body 2, and therefore, by electrically connecting the current collecting plate 4 and the bottom portion 30, the bottom portion 30 and the first electrode 21 can be electrically connected via the current collecting plate 4. The electrical connection between the current collecting plate 4 and the bottom portion 30 may be made using a wire such as a lead wire, a copper wire, or a braided wire, or may be made by brazing using solder or silver paste, or by welding such as laser welding.

[0030] In the present embodiment, it is preferable that the current collector 4 and the bottom 30 are mechanically connected. The current collector 4 is mechanically connected to the first electrode 21 of the wound body 2, and therefore by mechanically connecting the current collector 4 and the bottom 30, the bottom 30 and the first electrode 21 can be mechanically connected via the current collector 4. In other words, with the wound body 2 and the current collector 4 housed in the case 3, the wound body 2 and the current collector 4 can be fixed inside the case 3. The mechanical connection between the current collector 4 and the bottom 30 may be performed by adhesive, screwing, caulking, or the like, or may be performed by brazing using solder, silver paste, or the like, or by welding such as laser welding.

[0031] In this embodiment, it is particularly preferable that the current collecting plate 4 and the bottom portion 30 are electrically and mechanically connected. Specifically, as shown in FIG. 4B , it is preferable that the current collecting plate 4 and the bottom portion 30 are electrically and mechanically connected at a second weld 34 separate from the first weld 41. Brazing using solder or silver paste, or welding such as laser welding, is particularly preferable as a method for electrically and mechanically connecting the current collecting plate 4 and the bottom portion 30. In this case, the electrical and mechanical connection between the current collecting plate 4 and the bottom portion 30 can be achieved simultaneously. If the current collecting plate 4 and the bottom portion 30 are connected by laser welding, the second weld 34 corresponds to the weld mark of the laser welding. In FIG. 4B , the first electrode 21, the current collecting plate 4, and the first weld 41 are indicated by dotted lines. In this embodiment, it is preferable that the second weld 34 is located so as not to overlap with the first weld 41 when viewed from one side in the direction of the winding axis X. If the second weld 34 is positioned so as to overlap the first weld 41, the connection strength between the current collecting plate 4 and the bottom 30 may be reduced. In contrast, if the second weld 34 is positioned so as not to overlap the first weld 41, the current collecting plate 4 and the bottom 30 can be firmly connected. For example, when laser welding the current collecting plate 4 and the bottom 30 together, the position of the first weld 41 as seen from one side in the direction of the winding axis X is estimated based on the position of a notch 42 provided in the current collecting plate 4, and the current collecting plate 4 and the bottom 30 are welded so as not to overlap with the first weld 41. Furthermore, it is preferable that a plurality of second welds 34 be provided on the bottom 30. In this case, the area over which the bottom 30 and the current collecting plate 4 are connected is increased, thereby enabling the bottom 30 and the current collecting plate 4 to be more firmly connected.

[0032] The shape of the second weld 34 may be any shape as long as it does not overlap with the first weld 41 when viewed from one side of the winding axis X. In particular, in this embodiment, the second weld 34 is preferably linear and extends along the winding direction of the wound body 2 when viewed from one side of the winding axis X. In other words, the second weld 34 is preferably linear and extends along the winding direction of the first electrode 21. Since the first weld 41 is linear and spans multiple layers of the first electrode 21, the second weld 34 is linear and extends along the winding direction of the wound body 2, which makes it possible to ensure a welding area between the current collecting plate 4 and the bottom 30 while avoiding the first weld 41. Furthermore, in this embodiment, the total area of ​​the second weld 34 is preferably smaller than the total area of ​​the first weld 41. In other words, the welding area between the current collecting plate 4 and the bottom 30 is preferably smaller than the welding area between the first electrode 21 and the current collecting plate 4. While the current collecting plate 4 is a plate-like member, the first electrode 21 is a thin, sheet-like member. Therefore, the connection strength per unit weld area between the current collecting plate 4 and the bottom 30 tends to be greater than that between the first electrode 21 and the current collecting plate 4. Therefore, by making the total area of ​​the second welds 34 smaller than the total area of ​​the first welds 41 and preferentially increasing the weld area between the first electrode 21 and the current collecting plate 4, the connection strength between the first electrode 21 and the current collecting plate 4 can be more easily ensured. The bottom 30 of this embodiment preferably includes an opening 35 having a rupturable groove 350. That is, the opening 35 is a region of the bottom 30 that includes the groove 350. When gas is generated within the power storage device 1 due to repeated charging and discharging of the power storage device 1, the groove 350 ruptures, allowing the gas to be released, as shown in FIG. 4C . Arrows in FIG. 4C indicate the flow of gas. When first electrode 21 exposed at first winding end 24 is directly connected to bottom 30, it is necessary to secure an area for the weld between first electrode 21 and bottom 30, making it difficult to provide opening 35 in bottom 30. In contrast, in electricity storage device 1 of the present embodiment, first electrode 21 exposed at first winding end 24 is connected to current collector plate 4, and current collector plate 4 is also connected to bottom 30, making it easy to provide opening 35 in bottom 30.

[0033] In this embodiment, the thickness of the open portion 35 in the bottom 30 is preferably smaller than the thickness of the portion of the bottom 30 other than the open portion 35. In other words, the thickness of the portion of the bottom 30 other than the open portion 35 is preferably greater than the thickness of the open portion 35 in the bottom 30. In this case, the grooves 350 in the open portion 35 can be easily ruptured, and if gas is generated in the electricity storage device 1, this gas can be more easily released. Furthermore, if gas is generated in the electricity storage device 1, deformation of the portion of the bottom 30 other than the open portion 35 due to the pressure of the gas can be suppressed.

[0034] Furthermore, in this embodiment, it is preferable that the second welded portion 34 is located in a portion of the bottom 30 other than the open portion 35. If the second welded portion 34 is located in the open portion 35, the current collecting plate 4 may become disconnected from the bottom 30 if the groove 350 is ruptured by the pressure of gas generated inside the electricity storage device 1. In contrast, by positioning the second welded portion 34 in a portion other than the open portion 35, it is possible to prevent the current collecting plate 4 from becoming disconnected from the bottom 30 at the second welded portion 34 if the groove 350 is ruptured by the pressure of gas.

[0035] In this embodiment, it is particularly preferable that the thickness of the open portion 35 of the bottom 30 is smaller than the thickness of the portion of the bottom 30 other than the open portion 35, and that the second welded portion 34 is located in the portion of the bottom 30 other than the open portion 35. In this case, it is particularly possible to prevent the current collector plate 4 and the bottom 30 from being disconnected at the second welded portion 34.

[0036] In this embodiment, it is preferable that the opening 35 is recessed toward the inside of the case 3. In other words, it is preferable that the opening 35 is provided within a recess provided in the bottom 30. In this case, the groove 350 can be torn within the recess provided in the bottom 30 (see FIG. 5C). That is, the recess provided in the bottom 30 can ensure a space for the groove 350 to be torn.

[0037] Furthermore, in this embodiment, the positions of open portions 35 and through holes 40 preferably overlap when viewed from one side in the direction of winding axis X. In this case, gas generated within electricity storage device 1 and guided to through holes 40 can be easily released from open portions 35 (see FIG. 4C ). Therefore, gas generated by repeated charging and discharging of electricity storage device 1 can be efficiently released from open portions 35.

[0038] Furthermore, in this embodiment, it is preferable that the open portion 35 has a plurality of intersecting grooves 350 so that the grooves 350 can easily be torn. In other words, it is preferable that the open portion 35 has a plurality of grooves 350 and that the open portion 35 has an intersection where the plurality of grooves 350 intersect. In this embodiment, the plurality of grooves 350 intersect in a "+" shape (see FIG. 4B), but the shape of the plurality of grooves 350 is not particularly limited. Furthermore, it is preferable that the intersection of the plurality of grooves 350 and the position of the through hole 40 overlap when viewed from one side in the direction of the winding axis X. In this case, the grooves 350 can be easily torn by gas generated within the electricity storage device 1 and guided to the through hole 40 (see FIG. 4C). Therefore, gas generated by repeated charging and discharging of the electricity storage device 1 can be released particularly efficiently from the open portion 35.

[0039] The case 3 of this embodiment has an opening 32 facing the bottom 30 (see FIG. 1). The area near the opening 32 is drawn inward. The case 3 of this embodiment is also provided with a sealing body 33 that closes the opening 32. The edge of the opening 32 is curled so as to crimp the sealing body 33. The sealing body 33 is made of an elastic material that contains, for example, a rubber component.

[0040] As shown in FIG. 1A , terminal plate 27 is provided between sealing body 33 and wound body 2. Terminal plate 27 is a plate-shaped member. Terminal plate 27 is made of a conductive metal, such as aluminum, copper, nickel, iron, or stainless steel. Terminal plate 27 includes a connection portion 271 provided on its surface facing wound body 2 and an external terminal portion 270 provided on its surface facing sealing body 33. In this embodiment, second electrode 22 is exposed at second winding end 25 of wound body 2, and second electrode 22 is electrically connected to connection portion 271. This allows electrical connection between second electrode 22 and terminal plate 27. External terminal portion 271 penetrates sealing body 33, and its tip is exposed to the outside. That is, external terminal portion 271 allows terminal plate 27, which is connected to second electrode 22, to be exposed to the outside.

[0041] 2-4. Energy storage devices The electricity storage device 1 of this embodiment can be manufactured, for example, as follows.

[0042] First, the first electrode 21 exposed at the first winding end 24 of the wound body 2 is electrically and mechanically connected to the current collector 4 by laser welding. Next, the wound body 2 and the current collector 4 are inserted into the case 3 through the opening 32 of the case 3. Next, the bottom 30 of the case 3 and the current collector 4 are electrically and mechanically connected by laser welding. Next, a nonaqueous electrolyte is supplied into the case 3. This nonaqueous electrolyte is conductive to lithium ions and contains, for example, a lithium salt and a nonaqueous solvent that dissolves the lithium salt. Next, the opening 32 is sealed with a sealing member 33. In this manner, the electricity storage device 1 of this embodiment can be manufactured.

[0043] 2-5. Energy storage module As shown in FIGS. 5A and 5B , the power storage module 100 of this embodiment includes a plurality of the above-described power storage devices 1. The power storage module 100 includes three power storage devices 1. The three power storage modules 100 include a first power storage device 101, a second power storage device 102, and a third power storage device 103. The number of power storage devices 1 included in the power storage module 100 is not particularly limited as long as it is two or more. The plurality of power storage devices 1 are electrically and mechanically connected by conductive members 110 having conductivity. The conductive members 110 are not particularly limited as long as they are conductive, and may be made of metal, for example. Examples of materials for the conductive members 110 include copper, brass, and aluminum. The conductive members 110 are, for example, bus bars.

[0044] In the energy storage module 100 of this embodiment, the bottom 30 of the first energy storage device 101 and the bottom 30 of the second energy storage device 102 are electrically and mechanically connected by the conductive member 110. Furthermore, the bottom 30 of the second energy storage device 102 and the bottom 30 of the third energy storage device 103 are electrically and mechanically connected by the conductive member 110. The bottom 30 is electrically connected to the first electrode 21 of the wound body 2 included in the energy storage device 1, and therefore, in the energy storage module 100, the first electrodes 21 of the energy storage devices 1 are connected to each other. Furthermore, although not shown, it is preferable to connect the lead wires 270 of the energy storage devices 1 to each other. The lead wire 270 is electrically connected to the second electrode 22 of the wound body 2 included in the energy storage device 1. Therefore, by connecting the lead wires 270 of the energy storage devices 1 to each other, the second electrodes 22 of the energy storage devices 1 can be connected to each other. In this case, in the power storage module 100, the first power storage device 101, the second power storage device 102, and the third power storage device 103 can be connected in parallel.

[0045] Examples of methods for connecting bottom 30 and conductive member 110 include brazing using solder, silver paste, or the like, and laser welding. In this embodiment, bottom 30 and conductive member 110 are preferably connected by laser welding. For example, by laser welding bottom 30 and conductive member 110 of one power storage device 1 and then laser welding bottom 30 and conductive member 110 of the other power storage device 1, the two power storage devices 1 can be electrically and mechanically connected. In this embodiment, the welded portion of bottom 30 to conductive member 110 (third weld 111) is preferably located so as not to overlap first weld 41 when viewed from one side in the direction of winding axis X. Furthermore, third weld 111 is preferably located so as not to overlap second weld 34 when viewed from one side in the direction of winding axis X. If the third welded portion 111 is located at a position where it overlaps with the first welded portion 41, or if the third welded portion 111 is located at a position where it overlaps with the second welded portion 34, the connection strength between the bottom portion 30 and the conductive member 110 may be reduced. In contrast, by locating the third welded portion 111 at a position where it does not overlap with the first welded portion 41, and by locating the third welded portion 111 at a position where it does not overlap with the second welded portion 34, the connection strength between the bottom portion 30 and the conductive member 110 can be sufficiently ensured. Furthermore, the third welded portion 111 is preferably located in a portion of the bottom portion 30 other than the open portion 35. In this embodiment, the thickness of the portion of the bottom portion 30 other than the open portion 35 is greater than the thickness of the open portion 35. Therefore, by locating the third welded portion 111 in a portion of the bottom portion 30 other than the open portion 35, the connection strength between the bottom portion 30 and the conductive member 110 can be improved. Furthermore, in this embodiment, since the conductive member 110 is provided on the bottom 30 of the electricity storage device 1, the thickness of the conductive member 110 also ensures a space for the groove 350 of the opening 35 to rupture.

[0046] 3. Variations The configurations of the power storage device 1 and the power storage module 100 according to the above-described embodiments are merely examples, and the configurations of the power storage device 1 and the power storage module 100 are not limited to those of the above-described embodiments.

[0047] For example, the power storage device 1 may be a secondary battery such as a lithium ion battery, or may be an electrochemical device such as a lithium ion capacitor or an electric double layer capacitor, or may be any other electrochemical device.

[0048] 2A, the wound body 2 included in the power storage device 1 according to the above-described embodiment has the first electrode 21, separator 23, second electrode 22, and separator 23 stacked in this order, but is not limited to this. For example, the wound body 2 may have the second electrode 22, separator 23, first electrode 21, and separator 23 stacked in this order.

[0049] In the electricity storage device 1 according to the above embodiment, as shown in Fig. 3, the first electrode 21 exposed at the first winding end 24 and the current collector plate 4 are connected by three first welds 41. However, this is not limiting. For example, as in the electricity storage device 1 of a modified example shown in Fig. 6, the first electrode 21 exposed at the first winding end 24 and the current collector plate 4 may be connected by six first welds 41. These six first welds 41 each extend linearly across multiple layers of the first electrode 21 when viewed from one side in the direction of the winding axis X.

[0050] In the electricity storage device 1 according to the above embodiment, as shown in Fig. 4B, the bottom portion 30 has a plurality of grooves 350 that intersect in a "+" shape, but is not limited to this, and may have a plurality of grooves 350 that intersect in a shape other than a "+" shape.

[0051] In the electricity storage device 1 according to the above embodiment, the bottom 30 includes the open portion 35 as shown in FIG. 4B , but is not limited to this. For example, the bottom 30 may not include the open portion 35. In this case, the bottom 30 may have a constant thickness without including a thicker portion and a thinner portion. The bottom 30 may be flat without having a portion recessed into the inside of the case 3. The current collecting plate 4 may not have a through hole 40. The second weld 34 between the bottom 30 and the current collecting plate 4 may not be linear and extend in the winding direction of the wound body 2 when viewed from one side in the direction of the winding axis X. For example, the second weld 34 may extend linearly across multiple layers of the first electrode 21 when viewed from one side in the direction of the winding axis X.

[0052] 4. Overview of this Disclosure The electricity storage device (1) according to the first aspect includes a wound body (2) and a case (3), and further includes a current collector plate (4). The wound body (2) includes a first electrode (21) and a second electrode (22) wound around a winding axis (X), with the first electrode (21) exposed at a first winding end (24) located at one end in the direction of the winding axis (X). The case (3) accommodates the wound body (2) and is cylindrical with a bottom (30). The current collector plate (4) is electrically and mechanically connected to the first electrode (21) at the first winding end (24) and is located between the first winding end (24) and the bottom (30).

[0053] According to this configuration, the first electrode (21) exposed at the first winding end (24) is electrically connected to the current collector plate (4), thereby increasing the current collection area. Increasing the current collection area between the first electrode (21) and the current collector plate (4) reduces the resistance of the electricity storage device (1). Furthermore, since the wound body (2) connected to the current collector plate (4) is housed in the case (3), connection between the case (3) and the wound body (2) is easier than when directly connecting the case (3) and the wound body (2).

[0054] In the electricity storage device (1) according to the second aspect, the current collector plate (4) and the bottom part (30) are electrically connected to each other in the first aspect.

[0055] According to this configuration, the current collector (4) is electrically connected to the first electrode (21) of the wound body (2), and therefore the bottom (30) and the first electrode (21) can be electrically connected via the current collector (4).

[0056] In the electricity storage device (1) according to the third aspect, the current collector plate (4) and the bottom part (30) of the first or second aspect are mechanically connected to each other.

[0057] According to this configuration, the current collector (4) is mechanically connected to the first electrode (21) of the wound body (2), and therefore the bottom (30) and the first electrode (21) can be mechanically connected via the current collector (4).

[0058] An electricity storage device (1) according to a fourth aspect is any one of the first to third aspects, in which, at the first winding end (24), the first electrode (21) and the current collector plate (4) are electrically and mechanically connected by a first weld (41). The first weld (41) extends linearly across multiple layers of the first electrode (21) when viewed from one side in the direction of the winding axis (X).

[0059] This configuration allows for a large number of welded portions between the current collector plate (4) and the first electrode (21), thereby reducing the resistance of the electricity storage device (1). Furthermore, the current collector plate (4) and the first electrode (21) can be mechanically and firmly connected. Furthermore, the current collector plate (4) and the first electrode (21) can be easily welded together without visually inspecting the multiple layers of the first electrode (21).

[0060] In an electricity storage device (1) according to a fifth aspect, in the fourth aspect, the current collector plate (4) and the bottom (30) are electrically and mechanically connected by a second weld (34) separate from the first weld (41). The second weld (34) is located so as not to overlap with the first weld (41) when viewed from one side in the direction of the winding axis (X).

[0061] According to this configuration, the second welded portion (34) is located at a position that does not overlap the first welded portion (41), so that the current collector plate (4) and the bottom portion (30) can be mechanically connected firmly.

[0062] The electricity storage device (1) according to a sixth aspect is the fifth aspect, wherein the second welded portion (34) is linear and extends along the winding direction of the wound body (2) when viewed from one side in the direction of the winding axis (X).

[0063] According to this configuration, the first welded portion (41) is linear and extends across multiple layers of the first electrode (21), and the second welded portion (34) is linear and extends along the winding direction of the wound body (2). Therefore, the welding area between the current collector plate (4) and the bottom portion (30) can be secured while avoiding the first welded portion (41).

[0064] The electricity storage device (1) according to a seventh aspect is any one of the first to sixth aspects, wherein the bottom (30) includes an opening (35) having a cleavable groove (350).

[0065] According to this configuration, gas generated by repeated charging and discharging of the electricity storage device (1) can be released through the cleaved grooves (350).

[0066] The electricity storage device (1) according to an eighth aspect is the seventh aspect, wherein the thickness of the open portion (35) in the bottom portion (30) is smaller than the thickness of the portion of the bottom portion (30) other than the open portion (35).

[0067] This configuration allows the grooves 350 to be easily ruptured, and allows gas generated by repeated charging and discharging of the electricity storage device 1 to be easily released from the grooves 350. In addition, deformation of portions of the bottom 30 other than the open portions 35 due to the pressure of the gas generated in the electricity storage device 1 can be suppressed.

[0068] The electricity storage device (1) according to a ninth aspect is the seventh or eighth aspect, wherein the second welded portion (34) is located in a portion of the bottom portion (30) other than the open portion (35).

[0069] According to this configuration, even if the groove (350) is torn open by the pressure of gas generated by repeated charging and discharging of the electricity storage device (1), it is possible to prevent the connection between the current collector plate (4) and the bottom (30) at the second welded part (34) from coming loose.

[0070] The electricity storage device (1) according to a tenth aspect is any one of the seventh to ninth aspects, wherein the open portion (35) of the bottom portion (30) is recessed toward the inside of the case (3).

[0071] According to this configuration, the groove (350) can be torn apart within the recess provided in the bottom portion (30). That is, the recess provided in the bottom portion (30) ensures a space for the groove (350) to be torn apart.

[0072] The electricity storage device (1) according to an eleventh aspect is the electricity storage device (1) of any one of the seventh to tenth aspects, wherein a through hole (40) is provided in the current collector plate (4).

[0073] According to this configuration, gas generated by repeated charging and discharging of the electricity storage device (1) can be guided to the through-holes (40).

[0074] The electricity storage device (1) according to a twelfth aspect is the eleventh aspect, wherein the positions of the open portions (35) and the positions of the through holes (40) overlap when viewed from one side in the direction of the winding axis (X).

[0075] This configuration makes it possible to facilitate the release of gas generated in the electricity storage device (1) and introduced into the through-holes (40) through the open portions (35). As a result, gas generated by repeated charging and discharging of the electricity storage device (1) can be efficiently released through the open portions (35).

[0076] The energy storage module (100) according to a thirteenth aspect is the energy storage module (100) according to the eleventh or twelfth aspect, wherein the open portion (35) has a plurality of intersecting grooves (350), and the intersections of the plurality of grooves (350) and the positions of the through holes (40) overlap when viewed from one side in the direction of the winding axis (X).

[0077] According to this configuration, the grooves (350) can be easily ruptured by gas generated in the electricity storage device (1) and guided to the through-holes (40). Therefore, gas generated by repeated charging and discharging of the electricity storage device (1) can be released particularly efficiently from the openings (35).

[0078] The energy storage module (100) according to the fourteenth aspect includes a plurality of energy storage devices (1) according to any one of the first to thirteenth aspects, and the plurality of energy storage devices (1) are electrically and mechanically connected by a conductive member (110) having electrical conductivity.

[0079] According to this configuration, the resistance of the plurality of electricity storage devices (1) included in the electricity storage module (100) is reduced, and therefore the resistance of the electricity storage module (100) can also be reduced. [Explanation of symbols]

[0080] 1. Energy storage devices 2 wound body 21 1st electrode 22 2nd electrode 24 Volume 1 End 3 cases 30 bottom 4 Current collector plate X winding axis

Claims

1. a winding body including a first electrode and a second electrode wound around a winding axis, the first electrode being exposed at a first winding end located at one end in the winding axis direction; a cylindrical case that houses the wound body and has a bottom; a current collector located between the first winding end and the bottom, At the first winding end, the first electrode and the current collecting plate are welded to each other at a first welded portion, The current collecting plate and the bottom portion are welded to each other by a second weld portion different from the first weld portion, A total area of ​​the second welds is smaller than a total area of ​​the first welds, The bottom portion has a cleavable groove; The current collector plate is provided with a through hole, When viewed from the winding axis direction, the groove and the through hole are positioned to overlap each other. Energy storage device.

2. a winding body including a first electrode and a second electrode wound around a winding axis, the first electrode being exposed at a first winding end located at one end in the winding axis direction; a cylindrical case that houses the wound body and has a bottom; a current collector located between the first winding end and the bottom, the first electrode and the current collector plate are electrically and mechanically connected to each other at the first winding end, The current collector and the bottom are electrically connected to each other, The bottom portion has a cleavable groove; the current collecting plate has a through hole provided at a position overlapping with the winding axis, When viewed from the winding axis direction, the groove and the through hole are positioned to overlap each other. Energy storage device.

3. a winding body including a first electrode and a second electrode wound around a winding axis, the first electrode being exposed at a first winding end located at one end in the winding axis direction; a cylindrical case that houses the wound body and has a bottom; a current collector located between the first winding end and the bottom, the first electrode and the current collector plate are electrically and mechanically connected to each other at the first winding end, The current collector and the bottom are electrically connected to each other, The bottom has an opening whose thickness is smaller than the thickness of its surroundings, The opening has a cleavable groove, the current collecting plate has a through hole provided at a position overlapping with the winding axis, When viewed from the winding axis direction, the groove and the through hole are positioned to overlap each other. Energy storage device.

4. a winding body including a first electrode and a second electrode wound around a winding axis, the first electrode being exposed at a first winding end located at one end in the winding axis direction; a cylindrical case that houses the wound body and has a bottom; a current collector located between the first winding end and the bottom, At the first winding end, the first electrode and the current collecting plate are welded to each other at a first welded portion, The current collecting plate and the bottom portion are welded to each other by a second weld portion different from the first weld portion, A total area of ​​the second welds is smaller than a total area of ​​the first welds, The bottom portion has a cleavable groove; The bottom has an opening whose thickness is smaller than the thickness of its surroundings, The groove is provided in the opening, The current collector plate is provided with a through hole, When viewed from the winding axis direction, the groove and the through hole are positioned to overlap each other. Energy storage device.

5. a winding body including a first electrode and a second electrode wound around a winding axis, the first electrode being exposed at a first winding end located at one end in the winding axis direction; a cylindrical case that houses the wound body and has a bottom; a current collector located between the first winding end and the bottom, the first electrode and the current collector plate are electrically and mechanically connected to each other at the first winding end, The current collector and the bottom are electrically connected to each other, The bottom portion has a cleavable groove; The bottom has an opening whose thickness is smaller than the thickness of its surroundings, The groove is provided in the opening, the current collecting plate has a through hole provided at a position overlapping with the winding axis, When viewed from the winding axis direction, the groove and the through hole are positioned to overlap each other. Energy storage device.

6. The opening has a plurality of intersecting grooves, When viewed from the winding axis direction, the intersections of the plurality of grooves and the positions of the through holes overlap with each other. The electricity storage device according to any one of claims 3 to 5.

7. At the first winding end, the first electrode and the current collecting plate are welded to each other at a first welded portion, The current collecting plate and the bottom portion are welded by a second weld portion different from the first weld portion. The electricity storage device according to any one of claims 1 to 3.

8. The second welded portion is located in a portion of the bottom other than the open portion. The electricity storage device according to claim 7 .

9. the first welded portion extends linearly across a plurality of layers of the first electrode when viewed from the winding axis direction. The electricity storage device according to claim 7 or 8.

10. The second welded portion is located at a position not overlapping with the first welded portion when viewed from the winding axis direction. The electricity storage device according to any one of claims 7 to 9.

11. The second welded portion has a linear shape extending along the winding direction of the winding body when viewed from the winding axis direction. The electricity storage device according to any one of claims 7 to 10.

12. At the bottom, the opening is recessed toward the inside of the case. The electricity storage device according to any one of claims 3 to 5.

13. A storage battery comprising a plurality of the power storage devices according to any one of claims 1 to 12, The plurality of power storage devices are electrically and mechanically connected to each other by a conductive member having electrical conductivity. Energy storage module.

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