Energy storage cell, and method for manufacturing an energy storage cell

Abstract

According to the energy storage cell and the method for manufacturing the energy storage cell, it is possible to suppress the movement of the electrode body within the housing case and to suppress the decrease in energy density caused by the measures taken to prevent electrode body movement. [Solution] The energy storage cell 10 comprises an electrode body 40 and a housing case 20 that houses the electrode body 40. The housing case 20 includes a first side wall 21, a second side wall 22 that is spaced apart from the first side wall 21 in the arrangement direction W, and a main body portion 23 that connects the first side wall 21 and the second side wall 22. The main body portion 23 has a first end wall 24 and a second end wall 25 that is spaced apart from the first end wall 24 with the electrode body 40 in between. The first end wall 24 has an exhaust valve 24a and a projection 24b that protrudes toward the electrode body 40.

Description

[[Technical Field]]

[0001] The present disclosure relates to an electricity storage cell and a method for manufacturing an electricity storage cell. [[Background Art]]

[0002] Various proposals have been made for electricity storage cells included in power storage devices mounted on vehicles. For example, Japanese Unexamined Patent Publication No. 2000-067821 discloses an electricity storage cell including a housing case and an electrode assembly housed in the housing case. The housing case has a first end wall, a second end wall, and a peripheral wall connecting the first end wall and the second end wall. The peripheral wall has a first side surface and a second side surface opposite to the first side surface with the electrode assembly interposed therebetween. An exhaust valve is formed on the first end wall. Recesses are formed in the first side surface and the second side surface. The recesses can suppress movement of the electrode assembly within the housing case, and can suppress damage to the electrode assembly. [[Prior Art Literature]] [[Patent Literature]]

[0003] [[Patent Literature 1]] Japanese Unexamined Patent Publication No. 2000-067821 [[Patent Literature 2]] Japanese Unexamined Patent Publication No. 2013-243075 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0004] Recesses are formed in the first side surface and the second side surface of the electricity storage cell disclosed in Japanese Unexamined Patent Publication No. 2000-067821. This creates spaces between the first side surface and the electrode assembly, and between the second side surface and the electrode assembly, respectively. The space created by the recesses contributes to a reduction in the energy density of the electricity storage cell. Further, it is preferable that a gap is provided between the exhaust valve formed on the first end wall and the electrode assembly. This is to secure an exhaust path for gas generated within the housing case. On the other hand, securing an exhaust path between the exhaust valve and the electrode assembly may promote a reduction in the energy density of the electricity storage cell.

[0005] This disclosure has been made in view of the above-mentioned problems, and its purpose is to provide an energy storage cell that can suppress the movement of electrode bodies within the housing case and suppress the decrease in energy density due to measures to prevent electrode body movement, and a method for manufacturing an energy storage cell. [Means for solving the problem]

[0006] The energy storage cell according to this disclosure comprises an electrode body and a housing case for housing the electrode body. The housing case includes a first side wall, a second side wall spaced apart from the first side wall in the direction of arrangement, and a main body connecting the first side wall and the second side wall. The main body has a first end wall and a second end wall spaced apart from the first end wall with the electrode body sandwiched between them. The first end wall has an exhaust valve and a projection projecting toward the electrode body.

[0007] The protrusion of the energy storage cell according to this disclosure may be formed by forming the first end wall in a concave shape.

[0008] The energy storage cell relating to this disclosure may further include external terminals. The external terminals may be provided on at least one of the first side wall or the second side wall.

[0009] The energy storage cell relating to this disclosure may further include external terminals. The external terminals may be provided on the first end wall.

[0010] The energy storage cell according to the manufacturing method of the energy storage cell described herein comprises an electrode body, a housing case for housing the electrode body, and an external terminal. The housing case includes a first side wall, a second side wall spaced apart from the first side wall in the direction of arrangement, and a main body connecting the first side wall and the second side wall. The main body has a first end wall and a second end wall spaced apart from the first end wall with the electrode body sandwiched between them. The first end wall has an exhaust valve and a projection projecting toward the electrode body. The external terminal has a first terminal provided on the first side wall and a second terminal provided on the second side wall. The electrode body, the external terminal, the first side wall, and the second side wall form an electrode body unit. A method for manufacturing an energy storage cell comprises the steps of preparing an electrode unit, inserting the electrode unit into the main body, joining the first side wall and the second side wall of the electrode unit to the main body, and pressing the first end wall to form a protrusion. [Effects of the Invention]

[0011] According to the energy storage cell described herein, it is possible to suppress the movement of the electrode body within the housing case and to suppress the decrease in energy density caused by measures to prevent electrode body movement. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram of a vehicle equipped with an energy storage device according to an embodiment of the present disclosure. [Figure 2] This is a schematic diagram of an energy storage device having an energy storage cell according to an embodiment of the present disclosure. [Figure 3] This is an exploded perspective view of the energy storage device in an embodiment of the present disclosure. [Figure 4] This is a perspective view of an energy storage cell in an embodiment of the present disclosure. [Figure 5] Figure 4 is a cross-sectional view of the energy storage cell as seen in the direction of the VV arrow. [Figure 6] This is a modified example of the energy storage cell in the embodiment of the present disclosure. [Figure 7] This is a flowchart illustrating a method for manufacturing an energy storage cell in an embodiment of the present disclosure. MODE FOR CARRYING OUT THE INVENTION

[0013] Hereinafter, embodiments and modifications of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding portions are denoted by the same reference signs, and description thereof will not be repeated. <EMBODIMENT> FIG. 1 is a schematic diagram of a vehicle equipped with an electricity storage device according to an embodiment of the present disclosure. FIG. 2 is a schematic diagram of an electricity storage device having an electricity storage cell according to an embodiment of the present disclosure. Note that the vertical direction H shown in FIG. 1 indicates the vertical direction of the vehicle 1. A width direction W indicates the width direction of the vehicle 1. A front-rear direction D indicates the front-rear direction of the vehicle 1. The width direction W is an example of the "arrangement direction" in the present disclosure.

[0014] The vehicle 1 includes a vehicle body 2 and an electricity storage device 3. The vehicle 1 includes, for example, a PHEV (Plug-in Hybrid Electric Vehicle), a BEV (Battery Electric Vehicle), or an FCEV (Fuel Cell Electric Vehicle). The electricity storage device 3 is disposed below a bottom portion 2a of the vehicle body 2.

[0015] FIG. 3 is an exploded perspective view of the electricity storage device according to the present embodiment. The electricity storage device 3 includes a storage case 4 and an electricity storage stack 9.

[0016] The storage case 4 includes an upper cover 5 and a lower case 6. The storage case 4 forms an accommodation space V defined by the upper cover 5 and the lower case 6.

[0017] The upper cover 5 is formed so as to cover the lower case 6 that is formed to open upward.

[0018] The lower case 6 includes a bottom wall 7 and an upright wall 8. The bottom wall 7 supports the power storage stack 9 in the vertical direction H. An opening 7a is formed in the bottom wall 7. The opening 7a is arranged at a position facing an exhaust valve 24a described later. The upright wall 8 is formed to rise upward from the bottom wall 7 in the vertical direction H.

[0019] The power storage stack 9 is housed in the housing space V and arranged on the upper surface of the bottom wall 7. The power storage stack 9 is formed of a plurality of power storage cells 10. The plurality of power storage cells 10 are arranged in the front-rear direction D. The power storage cell 10 is formed in a rectangular parallelepiped shape that is elongated in the width direction W.

[0020] FIG. 4 is a perspective view of the power storage cell according to the embodiment of the present disclosure. The power storage cell 10 is a so-called prismatic battery formed to extend in the width direction W. The power storage cell 10 may be a chargeable-dischargeable secondary battery such as a lithium ion battery or a nickel metal hydride battery. The power storage cell 10 includes a housing case 20, an external terminal 30, and an electrode body 40.

[0021] The housing case 20 has electrical conductivity. The housing case 20 is made of a metal such as aluminum, for example. The housing case 20 houses the electrode body 40. The housing case 20 also houses an electrolyte solution not shown in FIG. 4. The housing case 20 has a first side wall 21, a second side wall 22, and a main body portion 23. The first side wall 21 and the second side wall 22 are arranged at an interval in the width direction W. The main body portion 23 connects the first side wall 21 and the second side wall 22. The main body portion 23 is formed in a cylindrical shape. When viewed from the width direction W away from the main body portion 23, the main body portion 23 has a substantially rectangular outer shape. The first side wall 21 is joined to an edge portion of the main body portion 23. The second side wall 22 is joined to an outer peripheral edge portion of the main body portion 23.

[0022] The main body portion 23 has a first end wall 24 and a second end wall 25. The first end wall 24 and the second end wall 25 sandwich the electrode body 40 therebetween and are arranged at an interval in the vertical direction H. In the embodiment of the present disclosure, the first end wall 24 is located below the second end wall 25.

[0023] Figure 5 is a cross-sectional view of the energy storage cell shown in Figure 4, viewed in the direction of the VV arrow. The first end wall 24 has an exhaust valve 24a and a projection 24b formed thereon.

[0024] The exhaust valve 24a is located in the center of the first end wall in the width direction W. The exhaust valve 24a is a known exhaust valve. For example, Japanese Patent Application Publication No. 2013-243075 discloses an exhaust valve 24a having a general section that is machined to be thinner than the first end wall 24. A fracture groove is formed in the general section of the exhaust valve 24a. By appropriately designing this groove, the exhaust valve 24a is selectively fractured by a small increase in pressure inside the housing case 20. The groove is formed, for example, by a die and a punch. When viewed in plan in the vertical direction H, the groove is formed in an elliptical or linear shape.

[0025] The projection 24b is formed to protrude toward the electrode body 40. The projection 24b is formed by the first end wall 24, which is a plate-shaped member, being formed in a concave shape toward the electrode body 40. In the embodiment of this disclosure, two projections 24b are formed on the first end wall 24, spaced apart in the width direction W with the exhaust valve 24a in between. The formation of the projection 24b on the first end wall 24 creates a space R between the first end wall 24 and the electrode body 40.

[0026] The external terminal 30 has a first terminal 31 and a second terminal 32. Each of the first terminal 31 and the second terminal 32 is electrically connected to the electrode body 40. In the embodiments of this disclosure, the first terminal 31 is a positive terminal and the second terminal 32 is a negative terminal.

[0027] The first terminal 31 is provided on the first side wall 21. The first terminal 31 has a first conductive portion 31a and a first protective portion 31b. A portion of the first conductive portion 31a is located inside the housing case 20 and is in contact with the first tab 51, which will be described later, while a portion of the first conductive portion 31a is formed to be exposed from the housing case 20. The first protective portion 31b has electrical insulation properties. The first protective portion 31b is located between the first conductive portion 31a and the first side wall 21.

[0028] Similarly, the second terminal 32 is provided on the second side wall 22. The second terminal 32 has a second conductive portion 32a and a second protective portion 32b. A portion of the second conductive portion 32a is located inside the housing case 20 and is in contact with the second tab 52, which will be described later, while a portion of the second conductive portion 32a is formed to be exposed from the housing case 20. The second protective portion 32b has electrical insulation properties. The second protective portion 32b is located between the second conductive portion 32a and the second side wall 22.

[0029] The electrode body 40 is, for example, a wound electrode body. A wound electrode body is formed by winding a group of sheets, each consisting of a positive electrode sheet, a separator, and a negative electrode sheet stacked on top of each other.

[0030] The electrode body 40 has a first end face 40a, a second end face 40b, and a circumferential surface 40c. The first end face 40a and the second end face 40b are spaced apart in the width direction W. The first end face 40a faces the first side wall 21. The second end face 40b faces the second side wall 22. The circumferential surface 40c connects the first end face 40a and the second end face 40b.

[0031] The electrode body 40 further comprises a current collecting tab 50. The current collecting tab 50 has a first tab 51 and a second tab 52. The first tab 51 is provided so as to protrude from the first end face 40a toward the first side wall 21 in the width direction W. The second tab 52 is provided so as to protrude from the second end face 40b toward the second side wall 22 in the width direction W. The first tab 51 is electrically connected to a positive electrode sheet (not shown) of the electrode body 40. The second tab 52 is electrically connected to a negative electrode sheet (not shown) of the electrode body 40. The first tab 51 is electrically connected to the first conductive portion 31a. The second tab 52 is electrically connected to the second conductive portion 32a.

[0032] The energy storage cell 10 further comprises an insulating film 60. The insulating film 60 has electrical insulating properties. The insulating film 60 is made of a film-like material. The insulating film 60 is placed between the electrode body 40 and the housing case 20. The insulating film 60 electrically insulates the housing case 20 from the electrode body 40. The insulating film 60 includes a circumferential insulating portion 61 and an end insulating portion 62.

[0033] The circumferential insulating portion 61 is located between the electrode body 40 and the main body portion 23. The end face insulating portion 62 is located between the electrode body 40 and the first side wall 21, and between the electrode body 40 and the second side wall 22. An opening is formed in the end face insulating portion 62 through which the current collecting tab 50 passes.

[0034] An energy storage cell 10 according to the embodiment of this disclosure comprises a housing case 20 and an electrode body 40 housed in the housing case 20. The housing case 20 has a first end wall 24. An exhaust valve 24a and a projection 24b are formed on the first end wall 24. The projection 24b is formed to protrude toward the electrode body 40. The formation of the projection 24b creates a space R between the first end wall 24 and the electrode body 40.

[0035] The protrusion 24b of the energy storage cell 10 having such a configuration can suppress the movement of the electrode body 40 within the housing case 20. Furthermore, it is preferable that a space is formed between the exhaust valve 24a formed in the housing case 20 and the electrode body 40 to secure an exhaust path for gas generated within the housing case 20. In this case, the energy storage cell 10 of the present disclosure has the exhaust valve 24a and the protrusion 24b formed on the first end wall 24. As a result, the space R created by the protrusion 24b, which is formed to prevent movement of the electrode body 40, also serves to secure an exhaust path. In other words, compared to the case in which the exhaust valve 24a and the protrusion 24b are formed on different walls, when the exhaust valve 24a and the protrusion 24b are formed on the same wall (for example, the first end wall 24), it is possible to suppress a decrease in the energy density of the energy storage cell.

[0036] In the embodiments of this disclosure, the protrusion 24b is formed by the first end wall 24 being formed in a concave shape toward the electrode body 40. By holding the electrode body 40 with the housing case 20 without adding any new members to the energy storage cell 10, it is possible to suppress a decrease in the energy density per unit of power of the energy storage cell 10.

[0037] The protrusion 24b does not necessarily have to be formed by the first end wall 24 being formed in a concave shape. For example, a buffer member may be placed between the first end wall 24 and the electrode body 40. The buffer member may be, for example, an elastic material and may be formed to fill the space between the first end wall 24 and the electrode body 40.

[0038] In the embodiments of this disclosure, the first end wall 24 on which the exhaust valve 24a is formed is located below the second end wall 25 in the vertical direction H. This prevents gas ejected from the exhaust valve 24a from entering the passenger compartment space of the vehicle 1.

[0039] In the embodiments of this disclosure, an example is shown in which the external terminal 30 is provided on the first side wall 21 and the second side wall 22, respectively, but this disclosure is not limited thereto.

[0040] For example, the external terminal 30 may be provided on at least one of the first side wall 21 or the second side wall 22. More specifically, the first end face 40a of the electrode body 40 may be provided with a first tab 51 and a second tab 52. The first terminal 31 and the first tab 51 provided on the first side wall 21 are electrically connected. Similarly, the second terminal 32 and the second tab 52 provided on the second side wall 22 are electrically connected. This reduces the space between the second side wall 22 and the second end face 40b of the electrode body 40, thereby suppressing a decrease in the energy density of the energy storage cell 10.

[0041] For example, as shown in Figure 6, the external terminal 30 may be provided on the first end wall 24. More specifically, the first end face 40a of the electrode body 40 may face the first end wall 24. The first end face 40a may be provided with a first tab 51 and a second tab 52. The first end wall 24 may be provided with the first terminal 31 and the second terminal 32 of the external terminal 30. The first terminal 31 and the first tab 51 are electrically connected. The second terminal 32 and the second tab 52 are electrically connected. As a result, the current collecting tab 50 is positioned in the space R created by the formation of the protrusion 24b. That is, it is possible to avoid the formation of a space for positioning the current collecting tab 50, and a decrease in the energy density of the energy storage cell 10 can be suppressed. The first end wall 24 may be above or below the second end wall 25 in the vertical direction H. <Manufacturing method for energy storage cells> Next, an example of a method for manufacturing the energy storage cell 10 will be explained using Figure 7. Figure 7 is a flowchart relating to the method for manufacturing the energy storage cell 10. As shown in Figure 7, the method for manufacturing the energy storage cell 10 includes, in order, a preparation step S1, an insertion step S2, a bonding step S3, and a pressing step S4. The details of the process will be explained below.

[0042] Preparation step S1 will now be described. In preparation step S1, the electrode unit 10a and the main body 23 are prepared. The electrode unit 10a shown in Figure 5 is formed by a first side wall 21, a second side wall 22, an external terminal 30, and an electrode body 40 surrounded by an insulating film 60. The external terminal 30 has a first terminal 31 and a second terminal 32. The first terminal 31 is provided on the first side wall 21. The second terminal 32 is provided on the second side wall 22. At the first end face 40a, the first terminal 31 and the electrode body 40 are electrically connected. At the second end face 40b, the second terminal 32 and the electrode body 40 are electrically connected.

[0043] Referring again to Figure 7, in insertion step S2, the electrode unit 10a is inserted into the main body 23.

[0044] In joining process S3, the first side wall 21 and the second side wall 22 of the electrode unit 10a are joined to the main body 23.

[0045] In the pressing step S4, a portion of the first end wall 24 of the main body 23 is pressed toward the electrode body 40, forming a protrusion 24b on the first end wall 24. The order of the joining step S3 and the pressing step S4 does not matter.

[0046] In the embodiments of this disclosure, a pressing step S4 is performed after the insertion step S2. More specifically, after inserting the electrode unit 10a into the main body 23, a projection 24b is formed on the first end wall 24 of the main body 23. This allows the electrode unit 10a to be smoothly inserted into the main body 23 during the insertion step S2.

[0047] While embodiments of this disclosure have been described above, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The technical scope provided herein is defined by the claims and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0048] 1 Vehicle, 2 Body, 2a Bottom, 3 Energy storage device, 4 Storage case, 5 Upper cover, 6 Lower case, 7 Bottom wall, 7a Opening, 8 Upright wall, 9 Energy storage stack, 10 Energy storage cell, 10a Electrode unit, 20 Housing case, 21 First side wall, 22 Second side wall, 23 Main body, 24 First end wall, 24a Exhaust valve, 24b Protrusion, 25 Second end wall, 30 External terminal, 31 First terminal, 31a First conductive part, 31b First protective part, 32 Second terminal, 32a Second conductive part, 32b Second protective part, 40 Electrode body, 40a First end face, 40b Second end face, 40c Circumferential surface, 50 Current collection tab, 51 First tab, 52 Second tab, 60 Insulating film, 61 Circumferential insulating part, 62 End face insulation, R space, V accommodation space.

Claims

1. It comprises an electrode body and a housing case for housing the electrode body, The aforementioned housing case includes a first side wall, a second side wall arranged at a distance from the first side wall in the direction of arrangement, and a main body connecting the first side wall and the second side wall. The main body portion has a first end wall and a second end wall that sandwiches the electrode body between them and is arranged at a distance from the first end wall. A power storage cell having an exhaust valve and a projection that protrudes toward the electrode body formed on the first end wall.

2. The energy storage cell according to claim 1, wherein the projection is formed by the first end wall being formed in a concave shape.

3. It also has external terminals, The energy storage cell according to claim 1 or claim 2, wherein the external terminal is provided on at least one of the first side wall or the second side wall.

4. It also has external terminals, The external terminal is provided on the first end wall of the energy storage cell according to claim 1 or claim 2.

5. A method for manufacturing an energy storage cell comprising an electrode body, a housing case for housing the electrode body, and an external terminal, The aforementioned housing case includes a first side wall, a second side wall arranged at a distance from the first side wall in the direction of arrangement, and a main body connecting the first side wall and the second side wall. The main body portion has a first end wall and a second end wall that sandwiches the electrode body between them and is arranged at a distance from the first end wall. The first end wall is formed with an exhaust valve and a projection that protrudes toward the electrode body. The external terminal has a first terminal provided on the first side wall and a second terminal provided on the second side wall. The electrode body unit is formed by the electrode body, the external terminal, the first side wall, and the second side wall. The method for manufacturing the aforementioned energy storage cell is as follows: The steps include preparing the electrode unit and The steps include inserting the electrode unit into the main body, A step of joining the first side wall and the second side wall of the electrode unit to the main body, A method for manufacturing an energy storage cell, comprising the step of pressing the first end wall to form a protrusion.

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