Energy storage device and energy storage unit

Abstract

To increase load efficiency of a power storage device in an electronic product.SOLUTION: A power storage device 1 includes an electrode body 10, a case 20, an insulation member 30, and a collector 40. The collector 40 includes a terminal part 44 that is arranged to block a terminal mounting hole 25 via the insulation member 30, joined to the insulation member 30, exposed outside of the case 20 through the terminal mounting hole 25, and electrically connectable to an external member. The terminal part 44 is arranged further inward than an outer face 20a of the case 20. The terminal mounting hole 25 is sealed by the insulation member 30 and the collector 40. Such a configuration increases load efficiency in an electronic product since both of formation of a conductive pathway to the outside of the case 20 and sealing of the inside of the case 20 are achieved without installation of an electrode terminal protruding outside the case 20.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Energy storage devices such as lithium-ion secondary batteries are used as power sources for various electrical appliances. An example of this energy storage device (sealed battery) is disclosed in Patent Document 1 (JP 2021-86813 A). The energy storage device described in Patent Document 1 includes a case member having a terminal mounting hole, an electrode assembly housed inside the case member, a current collecting terminal, and an insulating material. The current collecting terminal has an electrode assembly connection portion disposed inside the case member and connected to the electrode assembly, an external connection portion disposed outside the case member, and a shaft portion positioned between the electrode assembly connection portion and the external connection portion and inserted into the terminal mounting hole. At least one of the electrode assembly connection portion and the external connection portion is configured to be sized to be insertable into the terminal mounting hole. The insulating material is integrally molded with the case member and the current collecting terminal so as to fill the gap between the terminal mounting hole and the current collecting terminal. The energy storage device described in Patent Document 1 is said to enable easier removal of electrodes to the outside. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-86813 Summary of the Invention [Problem to be solved by the invention]

[0004] As described in Patent Document 1, in a typical electricity storage device, a part of the current collecting terminal (external connection part) protrudes outside the case. On the other hand, the loading space for electricity storage devices in an electrical appliance is limited. Therefore, an external connection part that protrudes outside the case reduces the loading efficiency of electricity storage devices in an electrical appliance. [Means for solving the problem]

[0005] To address the above-mentioned problems, an electricity storage device having the following configuration is provided.

[0006] The electricity storage device disclosed herein includes an electrode assembly, a case that houses the electrode assembly and has a terminal mounting hole, an insulating material that continuously covers the peripheral wall and peripheral edge of the terminal mounting hole in the circumferential direction and is joined to the peripheral edge of the terminal mounting hole, and a current collector that is electrically connected to the electrode assembly inside the case. The current collector is disposed so as to close the terminal mounting hole via the insulating material and is joined to the insulating material. The current collector has a terminal portion that is exposed to the outside of the case through the terminal mounting hole and can be electrically connected to an external member. In the electricity storage device disclosed herein, the terminal portion is located inward from the outer surface of the case, and the terminal mounting hole is sealed by the insulating material and the current collector.

[0007] In the electricity storage device having the above configuration, a portion (terminal portion) of the current collector housed in the case is exposed to the outside of the case through the terminal mounting hole. The upper surface of this terminal portion is located inside the outer surface of the case. The terminal mounting hole of the case is sealed with an insulating material and the terminal portion. With this configuration, it is possible to form a conductive path to the outside of the case and seal the inside of the case without providing an electrode terminal (external connection member) that protrudes outside the case. Therefore, the electricity storage device disclosed herein can contribute to improving the loading efficiency of electrical products. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view schematically showing an electricity storage device according to a first embodiment. [Figure 2] FIG. 2 is an enlarged cross-sectional view schematically showing the structure in the vicinity of a terminal mounting hole of the electricity accumulation device according to the first embodiment. [Figure 3] FIG. 3 is an enlarged cross-sectional view illustrating a procedure for producing the insulating material in FIG. [Figure 4]FIG. 4 is a perspective view schematically showing the power storage unit according to the first embodiment. [Figure 5] FIG. 5 is an enlarged cross-sectional view schematically showing the connection structure of the electricity storage unit shown in FIG. [Figure 6] FIG. 6 is an enlarged cross-sectional view schematically showing the structure in the vicinity of a terminal mounting hole of the electricity accumulation device according to the second embodiment. [Figure 7] FIG. 7 is an enlarged cross-sectional view schematically showing the structure in the vicinity of a terminal mounting hole of an electricity storage device according to a third embodiment. [Figure 8] FIG. 8 is an enlarged cross-sectional view schematically showing the structure in the vicinity of a terminal mounting hole of an electricity accumulation device according to a fourth embodiment. [Figure 9] FIG. 9 is a cross-sectional view showing an example of a bus bar that can be used in the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the technology disclosed herein will be described with reference to the drawings. It should be noted that matters other than those specifically mentioned in this specification that are necessary for implementing the technology disclosed herein (e.g., the detailed configuration of the electrode body) can be understood as design matters for a person skilled in the art based on the prior art in the relevant field. The technology disclosed herein can be implemented based on the content disclosed in this specification and common technical knowledge in the relevant field. Furthermore, the expression "A to B" indicating a range in this specification is intended to include the meaning of "greater than A" and "smaller than B" as well as the meaning of "greater than A" and "smaller than B."

[0010] In this specification, the term "electricity storage device" refers to a concept that encompasses devices in which charge and discharge reactions occur due to the movement of charge carriers between a pair of electrodes (positive and negative electrodes). That is, the electricity storage device in the technology disclosed herein encompasses secondary batteries such as lithium ion secondary batteries, nickel-metal hydride batteries, and nickel-cadmium batteries, as well as capacitors such as lithium ion capacitors and electric double layer capacitors.

[0011] First Embodiment 1. Configuration of the energy storage device Hereinafter, one embodiment of the electricity storage device disclosed herein will be described with reference to FIGS. 1 to 3. FIG. 1 is a perspective view that schematically shows an electricity storage device according to a first embodiment. FIG. 2 is an enlarged cross-sectional view that schematically shows the structure of the vicinity of a terminal mounting hole of the electricity storage device according to the first embodiment. FIG. 3 is an enlarged cross-sectional view that explains the procedure for producing the insulating material in FIG. 2. Note that the symbols L, R, F, Rr, U, and D in the drawings represent left, right, front, rear, top, and bottom, respectively. Furthermore, the symbols X, Y, and Z in the drawings represent the width direction, depth direction, and height direction of the electricity storage device, respectively. However, these directions are merely defined for the convenience of explanation and do not limit the installation mode of the electricity storage device disclosed herein.

[0012] 1 and 2, an electricity storage device 1 according to this embodiment includes an electrode assembly 10, a case 20 that houses the electrode assembly 10 and has a terminal mounting hole 25, an insulating material 30 that continuously covers a peripheral wall 25a and peripheral edges 20a1, 20b1 of the terminal mounting hole 25 in the circumferential direction and is joined to the peripheral edges 20a1, 20b1 of the terminal mounting hole 25, and a current collector 40 that is electrically connected to the electrode assembly 10 inside the case 20. The current collector 40 is disposed so as to close the terminal mounting hole 25 via the insulating material 30, and is joined to the insulating material 30. The current collector 40 has a terminal portion 44 that is exposed to the outside of the case 20 through the terminal mounting hole 25 and can be electrically connected to an external member. In the electricity storage device 1 according to this embodiment, the terminal portion 44 is located inward from the outer surface 20a of the case 20, and the terminal mounting hole 25 is sealed by the insulating material 30 and the current collector 40. With this configuration, it is possible to form a conductive path to the outside of the case 20 and to seal the inside of the case 20 without providing an electrode terminal (external connection member) that protrudes outside the case. As a result, it is possible to contribute to improving the loading efficiency of electrical appliances. The electricity storage device 1 according to this embodiment will be specifically described below.

[0013] (1) Electrode body 10 The electrode assembly 10 is a power generating element of the electricity storage device 1. The electricity storage device 1 according to this embodiment includes one electrode assembly 10. However, the number of electrode assemblies is not particularly limited and may be multiple. Although detailed illustrations are omitted, the electrode assembly 10 includes a positive electrode plate, a negative electrode plate, and a separator. The positive electrode plate includes a positive electrode core made of conductive metal foil (such as aluminum foil) and a positive electrode active material layer applied to the surface of the positive electrode core. On the other hand, the negative electrode plate includes a negative electrode core made of conductive metal foil (such as copper foil) and a negative electrode active material layer applied to the surface of the negative electrode core. The separator is an insulating sheet interposed between the positive electrode plate and the negative electrode plate. Note that the materials of the components (positive electrode plate, negative electrode plate, separator, etc.) constituting the electrode assembly 10 can be materials that can be used in general electricity storage devices without particular limitations, and detailed description thereof will be omitted as they do not limit the technology disclosed herein.

[0014] The specific structure of the electrode assembly 10 is not particularly limited. For example, the electrode assembly 10 may be a wound electrode assembly formed by winding a laminate including a positive electrode plate, a negative electrode plate, and a separator. The electrode assembly 10 may also be a laminated electrode assembly formed by stacking multiple positive electrode plates, multiple negative electrode plates, and multiple separators. Regardless of the structure employed, connection tabs 12 are formed on both side edges of the electrode assembly 10 in the width direction X. One of the connection tabs 12 is a positive electrode tab electrically connected to the positive electrode plate. This positive electrode tab is formed, for example, by bundling positive electrode cores that are not coated with a positive electrode active material layer. The other connection tab 12 is a negative electrode tab electrically connected to the negative electrode plate. This negative electrode tab is formed by bundling negative electrode cores that are not coated with a negative electrode active material layer. As will be described in detail later, these connection tabs 12 are electrically connected to the current collector 40.

[0015] (2) Case 20 The case 20 is a container that houses the electrode assembly 10 and has a terminal mounting hole 25. Specifically, the case 20 is a flat, box-shaped container with an internal space. The electrode assembly 10 is housed in the internal space of the case 20. Although not shown in the drawings, an electrolyte is also housed inside the case 20. The electrolyte can be any electrolyte that can be used in general electricity storage devices without any particular restrictions, and as it does not limit the technology disclosed herein, a detailed description thereof will be omitted.

[0016] The case 20 in this embodiment includes a case body 22 and a sealing plate 24. The case body 22 is a box-shaped body with an upper opening. As shown in FIG. 1, the case body 22 includes a bottom 22b, which is a long rectangular plate-like member, a pair of first side walls 22c extending upward D from long sides (sides along the width direction X) of the bottom 22b, and a pair of second side walls 22d extending upward D from short sides (sides along the depth direction Y) of the bottom 22b. An upper opening surrounded by the upper ends of the first side wall 22c and the second side wall 22d is formed on the upper surface of the case body 22. Meanwhile, the sealing plate 24 is a rectangular plate-like member that closes the upper opening of the case body 22. Specifically, as shown in FIG. 2, the sealing plate 24 is fitted into the upper opening of the case body 22. The boundary between the case body 22 and the sealing plate 24 is joined by laser welding or the like. The case 20 (case body 22 and sealing plate 24) is preferably made of a metal having a certain level of strength or more. Examples of materials for the case 20 include metal materials such as aluminum and aluminum alloys.

[0017] As described above, the case 20 is formed with a terminal mounting hole 25. This terminal mounting hole 25 is a through-hole that penetrates the case 20. This terminal mounting hole 25 serves as an opening for forming a conductive path from the electrode assembly 10 inside the case 20 to the outside of the case 20. As shown in FIG. 1 , the terminal mounting hole 25 in this embodiment is a circular opening in a plan view. However, the planar shape of the terminal mounting hole is not particularly limited and may be rectangular. In addition, in the energy storage device 1 according to this embodiment, two terminal mounting holes 25 are formed in the sealing plate 24 of the case 20. Specifically, the terminal mounting holes 25 are formed at both ends of the sealing plate 24 in the width direction X. One of the terminal mounting holes 25 serves as a positive electrode terminal mounting hole 25P that forms a conductive path with the positive electrode of the electrode assembly 10. The other terminal mounting hole 25 serves as a negative electrode terminal mounting hole 25N that forms a conductive path with the negative electrode of the electrode assembly 10. The following description will be given taking the structure around the negative terminal mounting hole 25N as an example.

[0018] (3) Insulation 30 The insulating material 30 continuously covers the peripheral wall 25a of the terminal mounting hole 25 and the peripheral edges 20a1 and 20b1 of the terminal mounting hole 25 in the circumferential direction and is joined to the peripheral edges 20a1 and 20b1 of the terminal mounting hole 25. The insulating material 30 is a member for preventing electrical continuity to the case 20. Specifically, a current collector 40 that forms a conductive path from the electrode body 10 to the outside of the case 20 is attached inside the case 20. An external member (such as the bus bar 110 in FIG. 4) that connects the power storage device 1 to an electrical device is attached outside the case 20. By interposing the insulating material 30 between these conductive members and the case 20, electrical continuity to the case 20 can be prevented. The insulating material 30 is made of an insulating resin such as polypropylene resin, polyphenylene sulfide resin, polyamide resin, polyacetal resin, or polyimide resin. The insulating material 30 has an opening 38 that penetrates the insulating material 30. The insulating material 30 is formed so that the opening 38 overlaps the terminal mounting hole 25. In other words, the insulating material 30 is arranged so as not to block the terminal mounting hole 25 of the case 20.

[0019] The insulating material 30 in this embodiment is produced by insert molding. In this insert molding, first, as shown in FIG. 3 , the current collector 40 and a mold M are attached to the sealing plate 24. At this time, the positional relationship of each component is adjusted so that a cavity S having a shape corresponding to the insulating material 30 to be produced is formed. Next, a resin material is filled into the cavity S through an injection hole M1 of the mold M. The resin material is then cured to produce the insulating material 30 having a shape corresponding to the cavity S. When the insulating material 30 is produced by insert molding in this manner, the sealing plate 24 and the current collector 40 are integrated via the insulating material 30. As a result, the insulating material 30 continuously covers the peripheral wall 25a of the terminal mounting hole 25 and the peripheral edges 20a1 and 20b1 of the terminal mounting hole 25 in the circumferential direction and is bonded to the peripheral edges 20a1 and 20b1 of the terminal mounting hole 25. After insert molding, the insulating material 30 has an outer insulating portion 32, an inner insulating portion 34, and an in-hole insulating portion 36. The specific shape of each portion will be described below.

[0020] The insulating material 30 includes an external insulating portion 32 joined to a peripheral portion 20a1 of the terminal mounting hole 25 on the outer surface 20a of the case 20. The external insulating portion 32 prevents electrical conduction between the case 20 and an external member (such as the bus bar 110). Specifically, the external insulating portion 32 is a plate-shaped portion arranged along the outer surface 20a of the case 20 (the upper surface 24a of the sealing plate 24). The lower surface 32a of the external insulating portion 32 is joined to the outer surface 20a of the case 20 by insert molding. As shown in FIG. 4 , the provision of the external insulating portion 32 prevents the external member (the bus bar 110) from contacting the case 20 (the sealing plate 24) when connecting the external member to the power storage device 1. The thickness of the external insulating portion 32 is preferably 0.5 mm or more, more preferably 1.0 mm or more, and particularly preferably 2.0 mm or more. This more effectively prevents electrical conduction between the external member and the case 20. On the other hand, the thickness of the outer insulating part 32 is preferably 4.0 mm or less, and more preferably 3.0 mm or less, which allows the height dimension of the electricity storage device 1 to be further reduced, thereby further improving the loading efficiency of the electricity storage device in an electrical product.

[0021] The insulating material 30 also includes an internal insulating portion 34 that is bonded to a peripheral portion 20b1 of the terminal mounting hole 25 on the inner surface 20b of the case 20. The internal insulating portion 34 is a member that prevents electrical conduction between the case 20 and a current collector 40 (described later). Specifically, the internal insulating portion 34 is a plate-shaped portion that is interposed between the inner surface 20b of the case 20 (the lower surface 24b of the sealing plate 24) and a joint portion 42 of the current collector 40. The upper surface 34a of the internal insulating portion 34 is bonded to the inner surface 20b of the case 20 by insert molding. The thickness of the internal insulating portion 34 is preferably 0.1 mm or more, more preferably 0.3 mm or more, and particularly preferably 0.5 mm or more. This more effectively prevents electrical conduction between the current collector 40 and the sealing plate 24. The thickness of the internal insulating portion 34 is preferably 2.0 mm or less, and more preferably 1.0 mm or less. This increases the space for accommodating the electrode assembly 10 within the case 20, which can contribute to improving the performance of the electricity storage device 1.

[0022] The insulating material 30 includes an in-hole insulating portion 36 that is joined to the peripheral wall 25a of the terminal mounting hole 25. As will be described in detail later, in the electricity storage device 1 according to this embodiment, the current collector 40 and the bus bar 110 are connected inside the terminal mounting hole 25. The in-hole insulating portion 36 prevents these conductive members from directly contacting the case 20 (sealing plate 24). Specifically, the in-hole insulating portion 36 is a cylindrical portion extending along the height direction Z. The in-hole insulating portion 36 is disposed inside the terminal mounting hole 25 of the case 20. The outer periphery 36a of the in-hole insulating portion 36 is joined to the peripheral wall 25a of the terminal mounting hole 25. In addition, in the insulating material 30 according to this embodiment, the external insulating portion 32 and the internal insulating portion 34 are continuous via the in-hole insulating portion 36. In other words, the external insulating portion 32, the internal insulating portion 34, and the in-hole insulating portion 36 are integrally formed. The thickness of the in-hole insulating portion 36 is preferably 0.5 mm or more, more preferably 1.0 mm or more, and particularly preferably 2.0 mm or more. This prevents the in-hole insulating portion 36 from being damaged by friction or heat when connecting the current collector 40 and the bus bar 110. On the other hand, the thickness of the in-hole insulating portion 36 is preferably 4.0 mm or less, and more preferably 3.0 mm or less. This ensures that the terminal mounting hole 25 is sufficiently large, making it easy to connect the current collector 40 and the bus bar 110.

[0023] Furthermore, the insulating material 30 in this embodiment has a protrusion 34c that protrudes downward D from a portion of the internal insulating portion 34 (the inner portion in the width direction X). This makes it possible to regulate the up and down movement of the electrode body 10 within the case 20. As a result, it is possible to prevent contact between the electrode body 10 and the sealing plate 24 and damage to the connection tab 12. The thickness (protrusion amount) of the protrusion 34c is preferably 2.0 mm or more, and more preferably 3.0 mm or more. This makes it possible to more suitably regulate the up and down movement of the electrode body 10. Meanwhile, the thickness of the protrusion 34c is preferably 5.0 mm or less, and more preferably 4.0 mm or less. This makes it possible to ensure sufficient storage space for the electrode body 10 within the case 20.

[0024] In this embodiment, the surfaces of the metal members (sealing plate 24, current collector 40) that come into contact with the insulating material 30 are roughened. Specifically, the roughened portions are the peripheral edge 20a1 of the terminal mounting hole 25 on the outer surface 20a of the case 20, the peripheral edge 20b1 of the terminal mounting hole 25 on the inner surface 20b of the case 20, the peripheral wall 25a of the terminal mounting hole 25, and the surface of the current collector 40 (the upper surface 42a of the joint 42) that is joined to the insulating material 30. This allows the resin material to penetrate into the irregularities on the surfaces of each metal member during insert molding. This creates an anchor effect, thereby more firmly bonding the insulating material 30 and the metal member. Note that the roughening need only be applied to at least one location on each of the above-mentioned surfaces. Even in this case, the bonding strength between the insulating material 30 and the metal member can be suitably improved. This roughening does not limit the technology disclosed herein. That is, even if the surface is not roughened, the insulating material 30 and the metal member can be sufficiently integrated by insert molding.

[0025] (4) Current collector 40 The current collector 40 is a conductive member electrically connected to the electrode assembly 10 inside the case 20. Specifically, the current collector 40 has an internal current collecting portion 46 extending along the height direction Z. This internal current collecting portion 46 is a plate-shaped portion connected to the connection tab 12 of the electrode assembly 10. The internal current collecting portion 46 is preferably made of the same metal material as the connection tab 12 to be connected. For example, as described above, the negative electrode tab is made of a negative electrode core that is copper foil. In this case, the internal current collecting portion 46 is preferably made of a copper-based material (copper, copper alloy, etc.). This allows the current collector 40 and the electrode assembly 10 to be firmly connected with low resistance.

[0026] Moreover, the current collector 40 in this embodiment is disposed so as to cover the terminal mounting hole 25 via the insulating material 30, and is joined to the insulating material 30. The current collector 40 has a terminal portion 44 that is exposed to the outside of the case 20 through the terminal mounting hole 25 and can be electrically connected to an external member. A current collector having such a configuration will be specifically described below.

[0027] First, the current collector 40 has a joint 42, which is a plate-like member joined to the insulating material 30. This joint 42 is joined to the lower surface 34b of the internal insulating portion 34 so as to close the terminal mounting hole 25 inside the case 20. More specifically, the joint 42 is formed by bending the upper end of the internal current collecting portion 46 so as to face the sealing plate 24. As a result, the joint 42 faces the inner surface 20b of the case 20 with the internal insulating portion 34 in between. The upper surface 42a of the joint 42 is joined to the lower surface 34b of the internal insulating portion 34 by insert molding. As a result, the lower end of the terminal mounting hole 25 is closed by the joint 42.

[0028] The terminal portion 44 is exposed to the outside of the case 20 through the terminal mounting hole 25. This allows an external member such as a bus bar to be electrically connected to the current collector 40. Specifically, as shown in FIG. 2, in this embodiment, the upper end of the terminal mounting hole 25 is open. As a result, a part of the current collector 40 (the terminal portion 44) is exposed to the outside of the case 20. This allows a part of the external member (the connection protrusion 112 of the bus bar 110) to be inserted into the terminal mounting hole 25 from outside the case 20 (see FIG. 4). As a result, the current collector 40 and the external member can be electrically connected to each other.

[0029] The terminal portion 44 of the electricity storage device 1 according to this embodiment is located inward from the outer surface 20a of the case 20. In other words, as shown in FIG. 2, the upper surface 44a of the terminal portion 44 is located on the lower D side of the outline L1 along the outer surface 20a of the case 20. This prevents a portion of the current collector 40 from protruding outside the case 20. Additionally, in the electricity storage device 1 according to this embodiment, the terminal mounting hole 25 is sealed by the insulating material 30 and the current collector 40 (the joint portion 42 and the terminal portion 44). This prevents the electrolyte from leaking and foreign matter from entering. As described above, the electricity storage device 1 according to this embodiment can form a conductive path to the outside of the case 20 and seal the inside of the case 20 without providing an external connection portion. That is, according to this embodiment, since there is no conductive member protruding outside the case 20, the height of the electricity storage device 1 can be reduced. As a result, the loading efficiency of the electricity storage device 1 in an electrical product can be improved.

[0030] In this embodiment, the terminal portion 44 is a convex terminal portion inserted into the terminal mounting hole 25 from the inside of the case 20. This raises the position of the upper surface 44a of the terminal portion 44 within the terminal mounting hole 25, facilitating connection between the terminal portion 44 and an external component. Inserting the convex terminal portion 44 into the terminal mounting hole 25 also restricts movement of the current collector 40 in the horizontal direction (the width direction X and the depth direction Y). This also prevents peeling at the bonding interface between the joint portion 42 and the internal insulating portion 34. The higher the position of the upper surface 44a of the terminal portion 44 within the terminal mounting hole 25, the easier it becomes to connect the terminal portion 44 to an external component. From this perspective, the distance H1 from the outer surface 20a of the case 20 to the upper surface 44a of the terminal portion 44 is preferably 2.0 mm or less, more preferably 1.0 mm or less, and even more preferably 0.5 mm or less. Furthermore, the upper surface 44a of the terminal portion 44 may be at substantially the same height as the outer surface 20a of the case 20 (i.e., the distance H1 is 0 mm). In this case, the terminal portion 44 can be more easily connected to an external member.

[0031] As described above, the current collector 40 shown in FIG. 2 includes a joint 42, which is a plate-like member joined to the insulating material 30. The convex terminal 44 shown in FIG. 2 is a columnar member joined to the upper surface 42a of the joint 42. This ensures a sufficient thickness for the terminal 44. As a result, an appropriate welding depth can be ensured when connecting the terminal 44 to an external member by laser welding or the like. Furthermore, when such a configuration is adopted, the material of the terminal 44 can be freely selected without being affected by the materials of the other parts (joint 42, internal current collecting portion 46).

[0032] For example, as shown in FIG. 2, a clad material including a first layer 47 and a second layer 45 can be used as the terminal portion 44. The first layer 47 of the terminal portion 44 is joined to the upper surface 42a of the joint portion 42 and is made of the same metal as the joint portion 42. This allows the terminal portion 44 and the joint portion 42 to be firmly joined. On the other hand, the second layer 45 is exposed to the outside of the case 20 through the terminal mounting hole 25 and is made of a different metal from the first layer 47. This allows a metal that can be easily connected to an external member to be disposed on the upper surface 44a of the terminal portion 44. For example, in the negative electrode side current collector 40, a copper-based material is used for the internal current collecting portion 46 and the joint portion 42 in consideration of connectivity with the negative electrode tab. On the other hand, in the construction of the energy storage unit 100 described below, an aluminum-based material is used for the external member (bus bar 110) in consideration of connectivity with the joint portion of the positive electrode side current collector. In this case, it is preferable that the first layer 47 of the terminal portion 44 is made of copper and the second layer 45 is made of aluminum. This allows a copper-to-copper bonding interface to be formed between the terminal portion 44 and the joint portion 42, and also allows an aluminum-to-aluminum bonding interface to be formed between the terminal portion 44 and the bus bar 110. As a result, a strong, low-resistance conductive path can be formed from the electrode body 10 to the bus bar 110.

[0033] 2. Configuration of the energy storage unit Next, a description will be given of an electricity storage unit 100 constructed using the electricity storage device 1 having the above configuration. Fig. 4 is a perspective view schematically showing an electricity storage unit in a first embodiment. Fig. 5 is an enlarged cross-sectional view schematically showing a connection structure of the electricity storage unit shown in Fig. 4.

[0034] The energy storage unit 100 shown in FIG. 4 includes a plurality of energy storage devices 1. Specifically, in this energy storage unit 100, the plurality of energy storage devices 1 are arranged in the depth direction Y so that the first side walls 22c of the cases 20 face each other. The number of energy storage devices 1 included in the energy storage unit 100 is not particularly specified and may be changed as appropriate depending on the purpose of the energy storage unit 100 (such as the required power and specifications of the electrical appliance to be used). In addition, in the energy storage unit 100 according to this embodiment, it is not necessary for all of the plurality of energy storage devices 1 to have the above-described configuration. For example, when the energy storage unit is mounted in an electrical appliance, only some of the plurality of energy storage devices may interfere with other components, which may necessitate reducing the height dimension of the entire energy storage unit. In such a case, it is advisable to adopt the above-described configuration only for the energy storage devices that interfere with other components. This improves the loading efficiency of the energy storage devices in the electrical appliance.

[0035] A pair of end plates 120 are arranged on both outer sides of the energy storage units 100 in the arrangement direction (depth direction Y). The pair of end plates 120 are bridged by a restraining beam member 130. This allows a restraining pressure to be applied to each of the energy storage devices 1 in the arrangement direction. Furthermore, a resin buffer member 150 is arranged between each of the arranged energy storage devices 1. This allows the restraining pressure applied to the energy storage devices 1 to be uniform.

[0036] The energy storage unit 100 includes a plurality of bus bars 110 that electrically connect the plurality of energy storage devices 1. The bus bars 110 are joined to the terminal portions 44 of the respective energy storage devices 1. Specifically, in the energy storage unit 100 shown in FIG. 4, the plurality of energy storage devices 1 are arranged such that the positive electrode terminal mounting hole 25P of one energy storage device 1 and the negative electrode terminal mounting hole 25N of the other energy storage device 1 are adjacent to each other. The bus bars 110 are connected to the terminal portions 44 present inside each of a pair of adjacent terminal mounting holes 25. The bus bars 110 are made of the same metal material (e.g., aluminum) as the positive electrode terminal portion 44.

[0037] As shown in FIG. 5 , the busbar 110 in this embodiment includes connection protrusions 112 that are inserted into the terminal mounting holes 25 from the outside of the case 20 and connected to the terminal portions 44 of the current collectors 40. This allows easy connection between the terminal portions 44 and the busbar 110, even when the terminal portions 44 are located inward (at the downward direction D) from the outer surface 20a of the case 20. Specifically, the connection protrusions 112 are formed by bending a portion of the busbar 110 so as to protrude toward the downward direction D. The connection protrusions 112 of the busbar 110 are inserted into the terminal mounting holes 25 from above U in the height direction Z. This brings the connection protrusions 112 into contact with the upper surfaces 44a of the terminal portions 44. In this state, the connection protrusions 112 and the terminal portions 44 are laser-welded together. This forms a weld that spans the connection protrusions 112 and the terminal portions 44, electrically connecting the terminal portions 44 and the busbar 110.

[0038] It should be noted that the technology disclosed herein does not limit the external member connected to the electricity storage device to the bus bar 110 configured as described above. For example, an electric wire or the like may be used as the external member. These external members can also be easily inserted into the terminal mounting holes, and can therefore be properly connected to the current collector (terminal portion) that is located inward from the outer surface of the case.

[0039] One embodiment of the technology disclosed herein has been described above. However, the technology disclosed herein is not limited to the above-described embodiment. Other embodiments of the technology disclosed herein will be described below. FIG. 6 is an enlarged cross-sectional view schematically showing the structure in the vicinity of a terminal mounting hole of an electricity storage device according to a second embodiment. FIG. 7 is an enlarged cross-sectional view schematically showing the structure in the vicinity of a terminal mounting hole of an electricity storage device according to a third embodiment. FIG. 8 is an enlarged cross-sectional view schematically showing the structure in the vicinity of a terminal mounting hole of an electricity storage device according to a fourth embodiment. FIG. 9 is a cross-sectional view showing an example of a bus bar that can be used in the fourth embodiment.

[0040] <Second embodiment> As shown in FIG. 2, the terminal portion 44 in the first embodiment is a columnar clad material including a first layer 47 and a second layer 45. However, the terminal portion in the technology disclosed herein is not limited to a columnar clad material. For example, the terminal portion 44 may be a columnar member made of a single metal material (see FIG. 6). Even when such a configuration is adopted, the loading efficiency of the electricity storage device 1 can be improved by arranging the upper surface 44a of the terminal portion 44 inward (downward D) from the outer surface 20a of the case 20.

[0041] Note that terminal portions 44 made of a single metal material are particularly suitable for use when the joint portion 42 and the external member (bus bar) are made of the same material. For example, in the positive electrode side current collector 40, an aluminum-based material is used for the internal current collecting portion 46 and the joint portion 42 in consideration of connectivity with the positive electrode tab (aluminum foil). On the other hand, as described above, an aluminum-based material is also used for the bus bar 110 when constructing the energy storage unit 100 (see FIG. 4). In such a configuration, even without using a clad material for the terminal portion 44, the conductive path from the electrode body 10 to the bus bar 110 can be constructed of an aluminum-based material, thereby forming a strong, low-resistance conductive path.

[0042] <Third embodiment> In the first and second embodiments, the pillar-shaped terminal portion 44 is joined to the upper surface 42a of the joint portion 42 (see FIGS. 2 and 6). However, the convex terminal portion 44 is not limited to this configuration. For example, when the joint portion 42 is a plate-shaped member, the convex terminal portion 44 can be formed by bending the joint portion 42 (see FIG. 7). This convex terminal portion 44 can be formed by pressing the plate-shaped joint portion 42. Even when the terminal portion 44 having such a configuration is inserted into the terminal mounting hole 25, it is possible to easily connect the terminal portion 44 to an external member and to restrict movement of the current collector 40 in the horizontal direction. Furthermore, according to the present embodiment, the number of parts of the current collector 40 can be reduced, which contributes to reducing material costs.

[0043] <Fourth embodiment> Furthermore, in the first to third embodiments, the convex terminal portion 44 is inserted into the terminal mounting hole 25. However, the current collector in the technology disclosed herein does not have to have a convex terminal portion. For example, as shown in FIG. 8 , the joint portion 42 and the terminal portion 44 may form a continuous flat surface. Even when such a configuration is adopted, the terminal mounting hole 25 can be sealed with the insulating material 30 and the terminal portion 44. Even when such a configuration is adopted, the terminal portion 44 is exposed to the outside of the case 20 through the terminal mounting hole 25, so that an external member and the current collector 40 can be electrically connected. Also in this case, the terminal portion 44 is disposed inward (downward D) from the outer surface 20a of the case 20, so that the loading efficiency of the electricity storage device in the electrical product can be improved.

[0044] When the fourth embodiment is adopted, it is preferable to increase the protrusion of the connection protrusion of the bus bar. This allows the bus bar and the terminal portion 44 to be properly connected. Furthermore, as shown in FIG. 9, the connection protrusion 112 of the bus bar 110 may be made of a clad material. In this case, the connection protrusion 112 is joined to the main body 114 of the bus bar 110 and has an upper layer 112a made of the same metal as the main body 114, and a lower layer 112b disposed below the upper layer 112a and made of the same metal as the terminal portion 44 of the energy storage device 1. This makes it possible to easily form a strong, low-resistance conductive path even when the terminal portion 44 is not a convex member.

[0045] The technology disclosed herein has been described in detail above. However, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above. In other words, the technology disclosed herein encompasses the aspects described in items 1 to 8 below.

[0046] [Item 1] An electrode body; a case that houses the electrode body and has a terminal mounting hole; an insulating material that covers the peripheral wall and the peripheral edge of the terminal mounting hole continuously in a circumferential direction and is joined to the peripheral edge of the terminal mounting hole; a current collector electrically connected to the electrode body inside the case; Equipped with The current collector is The insulating material is disposed so as to close the terminal mounting hole, bonded to the insulating material; a terminal portion exposed to the outside of the case through the terminal mounting hole and capable of being electrically connected to an external member; The terminal portion is located inward from an outer surface of the case, and the terminal mounting hole is sealed by the insulating material and the current collector.

[0047] [Item 2] Item 2. The power storage device according to item 1, wherein the terminal portion is a convex terminal portion inserted into the terminal mounting hole from the inside of the case.

[0048] [Item 3] the current collector includes a joining portion that is a plate-like member joined to the insulating material, Item 3. The electricity storage device according to item 2, wherein the convex terminal portion is a portion where the joint portion is bent.

[0049] [Item 4] the current collector includes a joining portion that is a plate-like member joined to the insulating material, 3. The power storage device according to item 2, wherein the convex terminal portion is a columnar member joined to an upper surface of the joint portion.

[0050] [Item 5] The pillar-shaped terminal portion is a first layer joined to an upper surface of the joint portion and made of the same metal as the joint portion; a second layer exposed to the outside of the case through the terminal mounting hole and made of a metal different from that of the first layer; 5. The power storage device according to item 4, comprising:

[0051] [Item 6] 6. The energy storage device according to any one of items 1 to 5, wherein a roughening process is applied to at least one of the peripheral portion of the terminal mounting hole on the outer surface of the case, the peripheral portion of the terminal mounting hole on the inner surface of the case, the peripheral wall of the terminal mounting hole, and a surface of the current collector joined to the insulating material.

[0052] [Item 7] A plurality of power storage devices; a plurality of bus bars electrically connecting the plurality of power storage devices; Equipped with An electricity storage unit, wherein at least one of the plurality of electricity storage devices is the electricity storage device according to any one of items 1 to 6, and the bus bar is joined to the terminal portion of the electricity storage device.

[0053] [Item 8] 8. The energy storage unit according to item 7, wherein the bus bar is inserted into the terminal mounting hole from the outside of the case and has a connection protrusion that is connected to the terminal portion of the current collector. [Explanation of symbols]

[0054] 1. Energy storage devices 10 Electrode body 12 Connections tab 20 cases 22 Case body 24 Sealing plate 25 Terminal mounting hole 30 Insulation 32 Outer insulation 34 Internal insulation 36 Inner hole insulation 38 Opening 40 Current collector 42 Joint 44 Terminal section 46 Internal current collector 100 Energy Storage Units 110 Busbar 112 connecting protrusion 120 End Plate 130 Restraining beam material 150 Cushioning material

Claims

1. An electrode body; a case that houses the electrode body and has a terminal mounting hole; an insulating material that covers the peripheral wall and the peripheral edge of the terminal mounting hole continuously in a circumferential direction and is joined to the peripheral edge of the terminal mounting hole; a current collector electrically connected to the electrode body inside the case; Equipped with The current collector is The insulating material is disposed so as to close the terminal mounting hole, bonded to the insulating material; a terminal portion exposed to the outside of the case through the terminal mounting hole and capable of being electrically connected to an external member; the terminal portion is located inward from an outer surface of the case, and the terminal mounting hole is sealed by the insulating material and the current collector; the terminal portion is a convex terminal portion inserted into the terminal mounting hole from the inside of the case, the current collector includes a joining portion that is a plate-like member joined to the insulating material, the protruding terminal portion is a columnar member joined to an upper surface of the joint portion, The pillar-shaped terminal portion is a first layer joined to an upper surface of the joint portion and made of the same metal as the joint portion; a second layer exposed to the outside of the case through the terminal mounting hole and made of a metal different from that of the first layer; The power storage device includes:

2. 2. The energy storage device according to claim 1, wherein a roughening process is applied to at least one of the peripheral portion of the terminal mounting hole on the outer surface of the case, the peripheral portion of the terminal mounting hole on the inner surface of the case, the peripheral wall of the terminal mounting hole, and the surface of the current collector joined to the insulating material.

3. A plurality of power storage devices; a plurality of bus bars electrically connecting the plurality of power storage devices; Equipped with An electricity storage unit, wherein at least one of the plurality of electricity storage devices is the electricity storage device according to claim 1, and the bus bar is joined to the terminal portion of the electricity storage device.

4. The electricity storage unit according to claim 3 , wherein the bus bar includes a connection protrusion that is inserted into the terminal mounting hole from the outside of the case and is connected to the terminal portion of the current collector.

Images