Battery cell

Abstract

The purpose of this invention is to provide a battery cell that can prevent damage or breakage of the current collector and reliably ensure conductivity between the current collector and the terminal. To solve the above problems, this invention provides a battery cell comprising: a power generation element having a plurality of current collectors; and a terminal extending in the stacking direction of the plurality of current collectors and electrically connected to the plurality of current collectors; wherein the terminal is inserted into holes formed in the plurality of current collectors, and a bent portion is formed at the contact point between the current collector and the terminal; and a spacing retaining member is disposed between the plurality of current collectors and around the contact point.

Description

Technical Field

[0001] This invention relates to a battery cell. Background Art

[0002] Previously, high-energy-density lithium-ion batteries and other rechargeable batteries were widely used. In recent years, research has been conducted on using rechargeable batteries for various applications, such as automotive, based on the goals of improving energy efficiency, increasing the proportion of renewable energy to mitigate adverse environmental impacts, and reducing CO2 emissions. A rechargeable battery has the following structure: a solid electrolyte (separator) exists between the positive and negative electrodes, and it is filled with a liquid or solid electrolyte (electrolyte).

[0003] In lithium-ion secondary batteries, whether using liquid or solid electrolytes, a positive electrode including a positive current collector, an electrolyte, and a negative electrode including a negative current collector are repeatedly stacked. Moreover, in each positive and negative electrode, multiple current collectors are pulled out from the same direction, then the multiple current collectors are bundled together and then connected to lead terminals (for example, see Patent Document 1).

[0004] As disclosed in Patent Document 1, when multiple current collectors are bundled together and connected to lead terminals, stress is generated due to the bending of the foil-shaped current collectors. Therefore, the current collectors may be damaged or broken due to vibration or other reasons. Therefore, it is also considered to allow each current collector to contact the lead terminal extending in the stacking direction of the current collector individually.

[0005] As a technique for bringing the current collector into contact with the lead terminal extending in the stacking direction of the current collector, one method is to gather the bundled current collectors at any end in the stacking direction and extend the lead terminal to contact the current collector only at that part (for example, see Patent Document 2).

[0006] [Previous Technical Documents]

[0007] (Patent Document)

[0008] Patent Document 1: Japanese Patent Application Publication No. 2008-159592

[0009] Patent Document 2: Japanese Patent Application Publication No. 2010-027494 Summary of the Invention

[0010] [Problems to be solved by the invention]

[0011] The technology disclosed in Patent Document 2 is the same as that disclosed in Patent Document 1. Since multiple current collectors are brought together, the current collectors may bend due to the thickness of the coating, and the current collectors may be damaged or broken. In addition, if the terminal is inserted into the hole formed in the current collector and the axial force generated by the rivet causes the current collector to press only on the terminal, the current collector will only contact the terminal on the end face. Therefore, there is a problem that the conductivity between the current collector and the terminal may not be reliably ensured.

[0012] The present invention was developed in view of the above-mentioned problems, and aims to provide a battery cell that can prevent damage and breakage of the current collector and reliably ensure conductivity between the current collector and the terminals.

[0013] [Technical means to solve the problem]

[0014] (1) The present invention relates to a battery cell comprising: a power generation element having a plurality of current collectors; and a terminal extending in the stacking direction of the plurality of current collectors and electrically connected to the plurality of current collectors; wherein the terminal is inserted into a hole formed on the plurality of current collectors, and a bend is formed at the contact portion between the current collectors and the terminal, and a spacing retaining member is disposed between the plurality of current collectors and around the contact portion.

[0015] According to the invention of (1), a battery cell can be provided that can prevent damage and breakage of the current collector and reliably ensure conductivity between the current collector and the terminal.

[0016] (2) The battery cell according to (1) has an outer casing having a hole for inserting the aforementioned terminal, the end of the aforementioned terminal in the aforementioned stacking direction extending to the outside of the aforementioned outer casing.

[0017] According to the invention of (2), the electrodes of the battery cells can be provided on the stacked end of the current collector.

[0018] (3) According to the battery cell described in (2), a curved portion is formed at the contact portion between the end face of the aforementioned hole of the aforementioned outer body and the aforementioned terminal.

[0019] According to the invention of (3), the sealing performance of the outer casing can be improved.

[0020] (4) According to the battery cell described in (3), wherein the bending amount of the bending portion of the aforementioned outer casing is less than the bending amount of the bending portion of the aforementioned current collector.

[0021] According to the invention of (4), it is possible to prevent the outer casing from entering between the current collector and the terminal, and to make reliable contact between the current collector and the terminal.

[0022] (5) The battery cell according to (3) or (4), wherein the diameter of one end of the aforementioned terminal disposed outside the aforementioned outer casing in the aforementioned stacking direction is greater than the diameter of the aforementioned terminal disposed inside the aforementioned outer casing, and a lead terminal or gap insert is disposed between the end of the aforementioned terminal and the aforementioned outer casing.

[0023] According to the invention of (5), it becomes easier to obtain current from the battery cell and the sealing of the outer casing can be improved.

[0024] (6) The battery cell according to (5), wherein the end of the aforementioned terminal is engaged with the aforementioned lead terminal or the aforementioned second spacer retaining member by any one of the following methods: protrusion, screw shape and rivet.

[0025] According to the invention of (6), the sealing performance of the outer casing can be further improved.

[0026] (7) The battery cell according to (1) has an outer casing that internally houses the aforementioned power generation element and the aforementioned terminal, and the aforementioned outer casing has a conductive layer on the contact surface where the aforementioned power generation element abuts against the stacked end face.

[0027] According to the invention of (7), the resistance of a single battery cell can be reduced and the airtightness can be improved.

[0028] (8) The battery cell according to (7), wherein the aforementioned outer casing has a resin layer, the resin layer covering the outer periphery of the aforementioned conductive layer on the aforementioned abutting surface, and the area of ​​the aforementioned conductive layer on the aforementioned abutting surface is greater than the area of ​​the aforementioned resin layer on the aforementioned abutting surface.

[0029] According to the invention of (8), the resistance of a single battery cell can be reduced and the airtightness can be improved. Attached Figure Description

[0030] Figure 1 This is a top view of a battery cell according to the first embodiment of the present invention.

[0031] Figure 2 yes Figure 1 The cross-sectional view along line AA in the diagram.

[0032] Figure 3 yes Figure 1 BB line cross-section view.

[0033] Figure 4 This is a cross-sectional view of a battery cell according to the second embodiment of the present invention.

[0034] Figure 5 This is a schematic diagram of the outer casing as viewed from the contact surface according to the second embodiment of the present invention. Detailed Implementation

[0035] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. The content of the present invention is not limited to the description of the following embodiment. In the following embodiment, a lithium-ion solid-state secondary battery is used as an example to describe a single battery cell; however, the present invention is not limited to the above, and can also be applied to solid-state secondary batteries other than lithium-ion secondary batteries.

[0036] First Implementation Method

[0037] <Overall Structure of a Single Battery Cell>

[0038] like Figures 1 to 3 As shown, the battery cell 1 of this embodiment has a negative electrode lead terminal 20 and a positive electrode lead terminal 30 as lead terminals, and an outer casing 6. As... Figure 2 and Figure 3 As shown, the battery cell 1 has a stacked structure as a power generation element, wherein the stacked structure comprises a negative electrode current collector 22, a negative electrode active material layer 23, a solid electrolyte layer 4, a positive electrode current collector 32, and a positive electrode active material layer 33, all housed within an outer casing 6. Figure 2 As shown, multiple negative current collectors 22 are pulled out from the end face of the laminate in the same direction and respectively abut against negative terminals 21a or 21b. Similarly, as Figure 3 As shown, multiple positive current collectors 32 are pulled out from the end face of the laminate in the same direction and respectively abut against the positive terminals 31a or 31b.

[0039] The aforementioned laminated structure, serving as a power generation element, has a negative electrode active material layer 23 laminated on both sides of each negative electrode current collector 22, and a positive electrode active material layer 33 laminated on the surface of each positive electrode current collector 32. These can be separate layers, or the current collector and the active material layer can be formed as a single unit. Furthermore, a solid electrolyte layer 4 is laminated between the negative electrode current collector 22 and the negative electrode active material layer 23 and the positive electrode current collector 32 and the positive electrode active material layer 33. Multiple of these laminated units can be repeatedly laminated, and the number of laminates is not particularly limited.

[0040] [Negative electrode current collector]

[0041] The negative electrode current collector 22 is not particularly limited, and any known current collector suitable for the negative electrode of a secondary battery can be used. As the negative electrode current collector 22, a foil-shaped metal foil can be used. Examples include stainless steel (SUS) foil, copper (Cu) foil, and other metal foils.

[0042] [Negative electrode active material layer]

[0043] The negative electrode active material constituting the negative electrode active material layer 23 is not particularly limited, and any material known as a negative electrode active material for secondary batteries can be used. Its composition is not particularly limited, and it may include a solid electrolyte, conductive additives, or binders, etc. Examples of negative electrode active materials include lithium metal, lithium alloys such as Li-Al alloys or Li-In alloys, and Li4Ti5O4. 12 Materials such as lithium titanate, carbon fiber, or graphite.

[0044] [Positive Current Collector]

[0045] The positive current collector 32 is not particularly limited, and any known current collector suitable for the positive electrode of a secondary battery can be used. As the positive current collector 32, a foil-shaped metal foil can be used. Examples include stainless steel (SUS) foil, aluminum (Al) foil, and other metal foils.

[0046] [Positive electrode active material layer]

[0047] There are no particular limitations on the positive electrode active material constituting the positive electrode active material layer 33; any material known as a positive electrode active material for secondary batteries can be used. There are no particular limitations on its composition; it may include a solid electrolyte, conductive additives, or binders. Examples of positive electrode active materials include transition metal chalcogenides such as titanium disulfide, molybdenum disulfide, and niobium selenide, as well as transition metal oxides such as lithium nickel oxide (LiNiO2), lithium manganese oxide (LiMnO2, LiMn2O4), and lithium cobalt oxide (LiCoO2).

[0048] [Negative and Positive Extremes]

[0049] Negative terminals 21a and 21b are conductive components with an approximately cylindrical shape, for example, composed of two components connected inside the outer casing 6 via a connecting component C. Negative terminals 21a and 21b extend in the stacking direction of the plurality of negative current collectors 22 in the aforementioned laminate and are electrically connected inside the outer casing 6 to the plurality of negative current collectors 22 pulled out from the aforementioned laminate. One end of negative terminal 21a is disposed outside the outer casing 6 and has a larger diameter than the negative terminal 21a disposed inside the outer casing 6. The construction of the negative terminal is not limited to the aforementioned two components; it can also be a single component. However, by constructing the negative terminal with the aforementioned two components, it is convenient to insert and fix the negative terminal into the hole formed on the negative current collector 22.

[0050] A negative lead terminal 20, serving as a lead terminal, is disposed between one end of the negative terminal 21a and the outer casing 6. The negative lead terminal 20 engages with the negative terminal 21a via a protrusion / recess 211. This improves the sealing performance of the laminate. Alternatively, a gap insert member, serving as a separate component, can be used instead of the negative lead terminal 20. There are no particular limitations on the gap insert member, as long as it is a conductive component capable of electrical connection with both the negative lead terminal 20 and the negative terminal 21a. The negative lead terminal 20 and the negative terminal 21a can also be engaged using either a screw shape or a rivet instead of the protrusion / recess.

[0051] Positive terminals 31a and 31b have the same structure as the negative terminals 21a and 21b described above.

[0052] [Solid electrolyte layer]

[0053] The solid electrolyte constituting the solid electrolyte layer 4 is not particularly limited, and examples include sulfide-based solid electrolyte materials, oxide-based solid electrolyte materials, nitride-based solid electrolyte materials, and halide-based solid electrolyte materials.

[0054] [Lead terminals]

[0055] The negative lead terminal 20 and the positive lead terminal 30 are not particularly limited, but preferably are flexible linear plate-shaped components such as aluminum (Al) and copper (Cu).

[0056] [Exterior body]

[0057] The outer casing 6 houses the aforementioned laminate, which serves as a power generation element. The outer casing 6 prevents air and moisture from entering the laminate. The outer casing 6 is composed of a laminated film containing an inorganic film such as aluminum foil and a resin layer.

[0058] <Connection structure between current collector and terminal>

[0059] like Figure 2 As shown, holes for inserting negative terminals 21a and 21b are formed on the plurality of negative current collectors 22 pulled out from the end face of the aforementioned laminate. The diameter of the holes formed on the negative current collectors 22 is smaller than the diameter of the negative terminals 21a and 21b disposed inside the outer casing 6 before insertion of the negative terminals 21a and 21b. Furthermore, the diameter of the holes is enlarged, and the negative terminals 21a and 21b are inserted into the holes formed on the plurality of negative current collectors 22. Consequently, a bend 221 is formed at the contact point between the negative terminals 21a and 21b and the plurality of negative current collectors 22.

[0060] The bent portion 221 is formed by enlarging the diameter of the hole formed on the negative electrode current collector 22, which is a metal foil, and therefore has stress in the direction of contact with the negative terminals 21a and 21b. This increases the contact area between the negative electrode current collector 22 and the negative terminals 21a and 21b, ensuring reliable contact and maintaining reliable conductivity between them. Furthermore, in Figures 1 to 3 In this configuration, the bending portions 221 are formed near the ends of the short sides of the plurality of negative current collectors 22, which are metal foils. However, the bending portions 221 can also be formed near the ends of the long sides of the plurality of negative current collectors 22, which are metal foils. This allows for a more balanced current distribution.

[0061] A hole for inserting the negative terminal 21a is formed on the outer casing 6. The diameter of the hole on the outer casing 6, before the negative terminal 21a is inserted, is smaller than the diameter of the negative terminal 21a disposed inside the outer casing 6. Furthermore, the diameter of the hole on the outer casing 6 is enlarged, and the negative terminal 21a is inserted into the hole. As a result, a bend is formed at the contact point between the end face of the hole and the negative terminal 21a. Therefore, reliable contact between the end face of the hole and the negative terminal 21a is possible. Conventionally, the lifespan of battery cells is shortened due to moisture seeping from the outer casing (made of laminated film, etc.) and the areas where the metal terminals extending from the ends of the outer casing are heat-welded. However, with the above structure, the sealing performance of the outer casing 6 can be improved, and the lifespan of the battery cells can be extended.

[0062] In addition to the above, it is preferable that the bending amount of the bent portion formed on the outer casing 6 is less than the bending amount of the bent portion 221 formed on the negative current collector 22. Therefore, even in the negative current collector 22 adjacent to the outer casing 6, it is possible to prevent the outer casing 6 from entering between the negative terminal 21a and the negative current collector 22, thus reliably ensuring the conductivity between the negative terminal 21a and the negative current collector 22. This structure can be achieved by setting the diameter of the hole formed on the negative current collector 22 before the negative terminal 21a is inserted to be smaller than the diameter of the hole formed on the outer casing 6.

[0063] like Figure 2As shown, spacers 5a, serving as spacing members, are arranged between the plurality of negative current collectors 22 pulled out from the end face of the aforementioned laminate and around the bent portions 221 that abut against the negative terminals 21a and 21b. The thickness of the spacers 5a in the lamination direction is almost the same as the spacing between adjacent negative current collectors 22 in the aforementioned laminate. Therefore, the plurality of negative current collectors 22 pulled out from the end face of the aforementioned laminate can be arranged substantially parallel without bending on the portion other than the bent portions 221 that abut against the negative terminals 21a and 21b. This prevents damage or breakage of the negative current collectors 22.

[0064] like Figure 3 As shown, among the plurality of positive current collectors 32 pulled out from the end face of the aforementioned laminate, holes for inserting positive terminals 31a and 31b are also formed. The positive current collectors 32, positive terminals 31a, and 31b have the same structure as the aforementioned negative current collectors 22, negative terminals 21a and 21b, and bends 321 are formed at the contact points between the positive terminals 31a and 31b and the plurality of positive current collectors 32. Thus, the same effect as the aforementioned negative current collectors 22, negative terminals 21a and 21b can be obtained.

[0065] like Figure 3 As shown, spacers 5a, serving as spacing members, are disposed between the plurality of positive current collectors 32 pulled out from the end face of the aforementioned laminate and around the bend 321. The thickness of the spacers 5a is almost the same as the spacing between adjacent positive current collectors 32 in the aforementioned laminate. On the other hand, in the laminate of this embodiment, since a negative current collector 22 is disposed at the laminated end on the positive terminal 31a side, a spacer 5b is disposed between the outer casing 6 and the positive current collector 32 at this location. The thickness of the spacer 5b is less than the thickness of the spacer 5a. At the laminated end on the positive terminal 31b side, the outer casing 6 side end of the positive terminal 31b, having a predetermined thickness, is sealed inside the outer casing 6. Therefore, spacers 5b, having a thickness less than that of the spacers 5a, are disposed between the positive current collectors 32 at the laminated end on the positive terminal 31b side.

[0066] <Battery Module>

[0067] When multiple battery cells 1 with the above-described structure are combined to form a battery module, the multiple battery cells 1 are arranged such that the negative electrode lead terminal 20 and the positive electrode lead terminal 30, which extend in the stacking direction of the laminate, are arranged horizontally, thereby forming a battery module without wasting space. In this case, it is preferable that, in a plan view viewed from the stacking direction of the laminate, the positions of the negative electrode lead terminal 20 and the positive electrode lead terminal 30 of the battery cell 1 are arranged in an alternating manner. Since the battery module is used, each battery cell 1 may sometimes expand and its thickness may change, but with the above-described structure, since the positions of the positive electrode lead terminal 30, whose thickness is prone to change, can be dispersed, the thickness of each battery module unit can be made uniform.

[0068] Second Implementation Method

[0069] Next, the second embodiment of the present invention will be described. For structures identical to those in the first embodiment described above, the same symbols will be used in the drawings, and descriptions will be omitted.

[0070] [Exterior body]

[0071] like Figure 4 As shown, the battery cell 1a of this embodiment includes: a laminated body having a negative electrode current collector 22, a negative electrode active material layer 23, a solid electrolyte layer 4, a positive electrode current collector 32, and a positive electrode active material layer 33 stacked thereon as power generation elements; and an outer casing 6a that houses the negative terminals 21a and 21b internally. Figure 4 The image shows an outer casing 6a that houses the negative terminals 21a and 21b, and an outer casing 6a that houses the positive terminals 31a and 31b with the same construction.

[0072] The outer casing 6a has a resin layer 61, a metal layer 62 serving as a conductive layer, and a resin layer 63. The resin layer 61 is the outermost layer disposed on the battery cell 1a, and the resin layer 63 is the innermost layer disposed on the battery cell 1a. Figure 5 As shown, a portion of the metal layer 62 extends outward toward the battery cell 1a to form a lead terminal 62a. The lead terminal 62a may also be composed of a component different from the metal layer 62, as long as it is electrically connected to the metal layer 62. Alternatively, a conductive material other than metal may be used to replace the metal layer 62.

[0073] like Figure 4 As shown, the metal layer 62 abuts against the negative current collector 22a disposed on one of the stacked end faces of the aforementioned laminate. Therefore, the current collected by the negative terminals 21a and 21b can flow into the lamination via the negative current collector 22a and the metal layer 62. Figure 5The lead terminal 62a is shown. Furthermore, the metal layer 62 also abuts against the positive current collector 32a disposed on another stacked end face of the aforementioned laminate.

[0074] Figure 5 This is a schematic diagram viewed from the contact surface side where the outer casing 6a abuts against the laminated body. (Example) Figure 5 As shown, a metal layer 62 is disposed at the center of the contact surface of the outer casing 6a. The outer periphery of the metal layer 62 is covered by a resin layer 63. Increasing the area of ​​the metal layer 62 on the contact surface reduces resistance. On the other hand, it is preferable that the area of ​​the resin layer 63 on the contact surface is as small as possible, as long as it can insulate the negative terminals 21a and 21b from the metal layer 62. From the above viewpoint, it is preferable that the area of ​​the metal layer 62 on the contact surface is larger than the area of ​​the resin layer 63.

[0075] The outer casing 6a with the above-described structure can be manufactured in such a way that, for example, one side of the resin layer of the laminated film, which is composed of a resin layer, a metal layer, and a resin layer stacked sequentially, can be cut through. Alternatively, instead of forming lead terminals 62a on the outer casing 6a, a portion of the resin layer 61 can be cut through, and lead terminals connected to the metal layer 62 can be provided. In conventional laminated batteries, gaps may form between the laminated film and the lead terminals, resulting in reduced airtightness. However, compared to conventional laminated batteries, the airtightness of the battery cell 1a can be improved using the above-described lead terminal structure. Alternatively, a portion of the metal layer 62 can be extended from one end of the outer casing 6a as a lead terminal.

[0076] Since the current is collected on the negative current collector 22a and the positive current collector 32a that abut against the metal layer 62 in the above-mentioned laminate, it is preferable to make them thicker than the negative current collector 22a and the positive current collector 32a.

[0077] The preferred embodiments of the present invention have been described above, but the content of the present invention is not limited to the above embodiments and appropriate changes can be made.

[0078] In the above embodiment, the negative current collector 22 and the positive current collector 32 were described as extending from their respective current collectors. However, this is not a limitation. The negative current collector 22 and the positive current collector 32 can be pulled out from the end face of the laminate, or they can be pulled out electrically connected to different components.

[0079] Figure Labels

[0080] 1. 1A battery cell

[0081] 20 negative lead terminal (lead terminal)

[0082] 30 Positive Lead Terminal (Lead Terminal)

[0083] 21a, 21b Negative Terminals

[0084] 31a, 31b Positive Terminals

[0085] 22 Negative current collector (current collector)

[0086] 32 Positive Current Collector (Current Collector)

[0087] 221, 321 bends

[0088] 5a and 5b gaskets (space retention components)

[0089] 6. 6a outer body

[0090] 62 Conductive layer (metal layer)

[0091] 63 resin layers

Claims

1. A solid-state secondary battery cell, comprising: a power generation element having a plurality of current collectors; and a terminal extending in the stacking direction of the plurality of current collectors and electrically connected to the plurality of current collectors; and, The aforementioned terminals are inserted into the holes formed in the aforementioned plurality of current collectors, and a bent portion is formed at the contact point between the aforementioned current collector and the aforementioned terminals. A spacing maintaining member is provided between the aforementioned plurality of current collectors and around the aforementioned contact portion.

2. The solid-state secondary battery cell according to claim 1, wherein, It has an outer casing, the outer casing having a hole for inserting the aforementioned terminal. The aforementioned terminal extends to the outside of the aforementioned outer casing at its end in the aforementioned stacking direction.

3. The solid-state secondary battery cell according to claim 2, wherein, A bend is formed at the end face of the aforementioned hole of the aforementioned outer body and at the contact portion of the aforementioned terminal.

4. The solid-state secondary battery cell according to claim 3, wherein, The bending amount of the aforementioned outer casing is less than the bending amount of the aforementioned current collector.

5. The solid-state secondary battery cell according to claim 3, wherein, The diameter of one end of the terminal disposed outside the aforementioned outer casing in the aforementioned stacking direction is larger than the diameter of the terminal disposed inside the aforementioned outer casing. A lead terminal or a gap insert is disposed between the end of the aforementioned terminal and the aforementioned outer casing.

6. The solid-state secondary battery cell according to claim 5, wherein, The end of the aforementioned terminal is engaged with the aforementioned lead terminal or the aforementioned spacer retaining member using any one of the following methods: protrusion, screw shape, and rivet.

7. The solid-state secondary battery cell according to claim 1, wherein, It has an outer casing that internally houses the aforementioned power generation element and the aforementioned terminals. The aforementioned outer casing has a conductive layer on the contact surface where the aforementioned power generation element abuts against the laminated end face.

8. The solid-state secondary battery cell according to claim 7, wherein, The aforementioned outer casing has a resin layer that covers the outer periphery of the aforementioned conductive layer on the aforementioned contact surface. The area of ​​the conductive layer on the aforementioned contact surface is larger than the area of ​​the resin layer on the aforementioned contact surface.

Images