Power storage unit and method for manufacturing power storage unit

Abstract

A power storage unit includes an electrode body and a case that houses the electrode body. The electrode body includes a first electrode. The first electrode has an insulating support layer and a first conductive layer and a second conductive layer formed on the insulating support layer. The first conductive layer and the second conductive layer are each formed of flaky metal powder.

Description

Technical Field

[0001] This disclosure relates to a battery storage unit and a method for manufacturing the battery storage unit. Background Technology

[0002] Japanese Patent Application Publication No. 2020-198290 discloses a cell having a composite current collector, which includes an organic support layer and a conductive layer disposed on the organic support layer. Summary of the Invention

[0003] In the aforementioned Japanese Patent Application Publication No. 2020-198290, a situation arose where the conductive layer could not follow the flexibility of the organic support layer (insulating support layer) when it was bent. Specifically, when the conductive layer and the organic support layer were bent together, gaps sometimes formed between the metal particles constituting the conductive layer, leading to cracks in the conductive layer. In this case, the organic support layer was exposed due to the formation of cracks. As a result, it was believed that the organic support layer would expand or contract due to gas permeation into the exposed organic support layer.

[0004] This disclosure was made to solve the above-mentioned problems, and its purpose is to provide a power storage unit and a method for manufacturing the power storage unit that can suppress the exposure of the insulating support layer due to cracks forming in the conductive layer stacked on the insulating support layer.

[0005] The first aspect of this disclosure relates to an energy storage unit comprising an electrode body and a housing for accommodating the electrode body. The electrode body includes electrode sheets. The electrode sheets have an insulating support layer and a conductive layer formed on the insulating support layer. The conductive layer is formed of flake metal powder.

[0006] The second aspect of this disclosure relates to a method for manufacturing an energy storage unit, comprising a step of forming an electrode body and a step of housing the electrode body in a housing. The step of forming the electrode body includes a step of preparing an insulating support layer and a step of forming a conductive layer by laminating flake metal powder on the insulating support layer.

[0007] The above and other objects, features, aspects and advantages of the present invention will become clear from the following detailed description relating to the invention, taken in conjunction with the accompanying drawings. Attached Figure Description

[0008] Figure 1 This is a perspective view showing the structure of the energy storage device and frame components of this embodiment.

[0009] Figure 2 This is a perspective view showing the structure of the energy storage unit in this embodiment.

[0010] Figure 3 This is an exploded perspective view showing the structure of the energy storage unit in this embodiment.

[0011] Figure 4 This is a cross-sectional view of the electrode body.

[0012] Figure 5 This is a partially enlarged cross-sectional view showing the structure of the first electrode and the first connector.

[0013] Figure 6 This is a schematic top view showing the structure of the first conductive layer.

[0014] Figure 7 This is a schematic cross-sectional view showing the structure of the first conductive layer and the insulating support layer.

[0015] Figure 8 This is a flowchart illustrating the manufacturing method of the energy storage unit according to this embodiment.

[0016] Figure 9 This diagram illustrates a method for forming a first conductive layer and a second conductive layer on an insulating support layer.

[0017] Figure 10 This is a schematic cross-sectional view showing the structure of the conductive layer and the insulating support layer in the first modified example of this embodiment.

[0018] Figure 11 This is a schematic cross-sectional view showing the structure of the conductive layer and the insulating support layer in the second variation of this embodiment. Detailed Implementation

[0019] Embodiments of this disclosure will be described with reference to the accompanying drawings. Furthermore, in the drawings referred to below, identical or equivalent components are labeled with the same numbers.

[0020] Figure 1 This is a perspective view showing the structure of an energy storage device 1 including an energy storage unit 100 according to an embodiment of the present disclosure. The energy storage device 1 is, for example, mounted on a vehicle (not shown). Examples of vehicles include hybrid electric vehicles, plug-in hybrid electric vehicles, and battery electric vehicles. Alternatively, the energy storage device 1 can be installed in an electrical device other than an electric vehicle (e.g., a stationary energy storage device).

[0021] Furthermore, the X, Y, and Z directions in this specification are mutually orthogonal. For example, the X and Y directions can be the front-back and left-right directions, respectively, when the energy storage device 1 is mounted on an electric vehicle. Additionally, the Z direction can be the up-down direction. Specifically, the Z1 and Z2 directions can be up and down, respectively.

[0022] The energy storage device 1 is mounted on a frame component 2 located at the bottom of the vehicle. The frame component 2 is formed into a generally quadrangular cylindrical shape that surrounds the energy storage device 1.

[0023] The energy storage device 1 includes multiple energy storage stacks 3. Each energy storage stack 3 is formed into a cuboid shape that is longer in the Y direction. The multiple energy storage stacks 3 are arranged in a manner that is aligned along the X direction. Each energy storage stack 3 contains multiple energy storage cells 100 arranged in the Y direction. In addition, Figure 1 For simplicity, only two energy storage stacks 3 are shown, and only the three energy storage units 100 in each energy storage stack 3 are shown.

[0024] Figure 2 This is a perspective view showing the energy storage unit 100 of this embodiment. Figure 2 As shown, the energy storage unit 100 is a so-called square battery. The energy storage unit 100 is configured as a rechargeable secondary battery. The energy storage unit 100 can be a secondary battery such as a lithium-ion battery or a nickel-metal hydride battery. The energy storage unit 100 can be used, for example, as a unit included in an energy storage module mounted in an electric vehicle.

[0025] The energy storage unit 100 includes an electrode body 10, a housing 20, a first external terminal 30A, a second external terminal 30B, a first terminal support 40A, and a second terminal support 40B. Additionally, in... Figure 2 In the diagram, electrode body 10 is roughly represented by a dashed line.

[0026] The housing 20 is conductive. The conductive portion of the housing 20 is made of a metal such as aluminum. The housing 20 houses the electrode body 10. The housing 20 also houses an electrolyte (not shown). Furthermore, the housing 20 is an example of the "receiving body" of this disclosure.

[0027] The housing 20 includes a housing body 21 and a cover 22. The housing body 21 includes a bottom wall 210 and a peripheral wall 211 rising from the bottom wall 210.

[0028] The cover 22 includes a cover body 220 and an insulating cover 221. The cover body 220 is joined to the peripheral wall 211 by welding or the like in a manner that blocks the opening of the peripheral wall 211.

[0029] The first external terminal 30A and the second external terminal 30B are arranged to be exposed to the outside in the energy storage unit 100. Furthermore, in this embodiment, the first external terminal 30A is the positive terminal and the second external terminal 30B is the negative terminal. The first external terminal 30A and the second external terminal 30B are arranged in the X direction.

[0030] The first terminal support 40A is secured to the cover body 220. The first terminal support 40A supports the first external terminal 30A from the outer periphery of the first external terminal 30A. The second terminal support 40B is secured to the cover body 220. The second terminal support 40B supports the second external terminal 30B from the outer periphery of the second external terminal 30B.

[0031] Figure 3 This is an exploded perspective view of the energy storage unit 100 according to this embodiment. The energy storage unit 100 also includes a first connecting member 50A, a second connecting member 50B, a first sealing ring 60A, a second sealing ring 60B, an insulating member 70, and a fuse protection part 80.

[0032] The bottom wall 210 includes a bottom body 212, an outer protective film 213, and an inner protective film 214. A peripheral wall 211 rises from the bottom body 212. A pressure relief valve SV is provided on the bottom body 212. The outer protective film 213 covers the pressure relief valve SV from the outside. The inner protective film 214 covers the pressure relief valve SV from the inside. The bottom body 212 and the pressure relief valve SV are made of a metal such as aluminum.

[0033] An opening is formed at the upper end of the peripheral wall 211. The peripheral wall 211 has a generally rectangular shape when viewed from the opening direction of the opening. The opening and the bottom wall 210 are arranged along the Z direction. The opening is located on the Z1 side of the bottom wall 210. The Z direction can be the height direction of the energy storage unit 100 or the vertical direction. The peripheral wall 211 is made of a metal such as aluminum.

[0034] The cover 22 also includes a sealing plug 222 and a plug cover 223. A first connecting hole 224A, a second connecting hole 224B, and an injection hole 225 are formed on the cover body 220. The injection hole 225 is a through hole used to inject electrolyte into the housing body 21 during the manufacturing process of the energy storage unit 100.

[0035] The sealing plug 222 seals the injection hole 225. The plug cover 223 covers the injection hole 225 and the sealing plug 222. The insulating cover 221 covers the injection hole 225, the sealing plug 222, and the plug cover 223.

[0036] The first connecting member 50A and the second connecting member 50B are conductive. At least a portion of the first connecting member 50A and the second connecting member 50B is disposed within the housing 20. The first connecting member 50A and the second connecting member 50B are respectively disposed at positions opposite to the electrode body 10 in the Z direction. The first connecting member 50A and the second connecting member 50B are respectively disposed on the Z1 side of the electrode body 10.

[0037] The first external terminal 30A or the first connecting member 50A is inserted through the first connecting hole 224A. The first external terminal 30A and the first connecting member 50A engage with each other. The first connecting member 50A engages with the electrode body 10. Thus, the first external terminal 30A is electrically connected to the electrode body 10.

[0038] The second external terminal 30B or the second connecting member 50B is inserted through the second connecting hole 224B. The second external terminal 30B and the second connecting member 50B engage with each other. The second connecting member 50B engages with the electrode body 10. Thus, the second external terminal 30B is electrically connected to the electrode body 10.

[0039] A first sealing ring 60A is disposed along the first connecting hole 224A. The first sealing ring 60A is positioned in the gap between the cover body 220 and the first external terminal 30A, sealing the gap. A second sealing ring 60B is disposed along the second connecting hole 224B. The second sealing ring 60B is positioned in the gap between the cover body 220 and the second external terminal 30B, sealing the gap. The first sealing ring 60A and the second sealing ring 60B are electrically insulating.

[0040] The first terminal support portion 40A includes a first locking ring 41A and a first covering ring 42A. The first locking ring 41A extends annularly around the first connecting hole 224A and is directly locked to the cover body 220. The first covering ring 42A covers the first locking ring 41A. The first locking ring 41A supports the first external terminal 30A via the first covering ring 42A. The first covering ring 42A is made of a resin component with electrical insulation or weak conductivity.

[0041] The second terminal support 40B includes a second locking ring 41B and a second covering ring 42B. The second locking ring 41B extends annularly around the second connecting hole 224B and is directly locked to the cover body 220. The second covering ring 42B covers the second locking ring 41B. The second locking ring 41B supports the second external terminal 30B via the second covering ring 42B. The second covering ring 42B is made of an electrically insulating resin component.

[0042] The insulating component 70 is electrically insulating. The insulating component 70 is disposed between the electrode body 10 and the housing 20. The insulating component 70 electrically insulates the electrode body 10 and the housing 20 from each other. The insulating component 70 includes an insulating support 71, a peripheral insulating portion 72, a bottom insulating portion 73, and an adhesive tape 74.

[0043] An insulating bracket 71 is disposed between the electrode body 10 and the cover body 220. The insulating bracket 71 has high rigidity and is in contact with both the electrode body 10 and the cover body 220. Thus, the electrode body 10 is fixed to the housing 20 in the Z direction.

[0044] A peripheral insulating portion 72 is disposed between the electrode body 10 and the peripheral wall 211. The peripheral insulating portion 72 is composed of a thin film-like component.

[0045] The bottom insulating portion 73 is disposed between the electrode body 10 and the bottom wall 210. The bottom insulating portion 73 is composed of a thin film-like component. The bottom insulating portion 73 is fixed (bonded) to the housing 20 (bottom wall 210) by adhesive tape 74.

[0046] The energy storage unit 100 of this embodiment includes a plurality of electrode bodies 10. The energy storage unit 100 of this embodiment includes two electrode bodies 10. These electrode bodies 10 are arranged in the Y direction. The peripheral insulating portion 72 can integrally cover the plurality of electrode bodies 10 in a manner that fixes them together.

[0047] Each of the plurality of electrode bodies 10 is provided with at least one first connector 90A and at least one second connector 90B. In this embodiment, each of the plurality of electrode bodies 10 is provided with a plurality of first connectors 90A and a plurality of second connectors 90B. Each first connector 90A electrically connects a first electrode 10A (described later) to a first connecting member 50A. Each second connector 90B electrically connects a second electrode 10B (described later) to a second connecting member 50B.

[0048] Multiple first connectors 90A are arranged in a manner that is mutually aligned in the Y direction. The multiple first connectors 90A are joined together, for example, by ultrasonic welding. The multiple first connectors 90A are joined to a first connecting member 50A, for example, by ultrasonic welding. Multiple second connectors 90B are arranged in a manner that is mutually aligned in the Y direction. The multiple second connectors 90B are joined together, for example, by ultrasonic welding. The multiple second connectors 90B are joined to a second connecting member 50B, for example, by ultrasonic welding.

[0049] Figure 4 This is a cross-sectional view of the electrode body 10 in the XY plane. The electrode body 10 includes a first electrode 10A, a second electrode 10B, a diaphragm 10C, and a strip member 10D. The electrode body 10 is wound such that the first electrode 10A, the second electrode 10B, and the diaphragm 10C surround the winding axis α. Thus, in this embodiment, the electrode body 10 is a so-called wound electrode body, but it can also be a stacked electrode body in which the first electrode 10A, the second electrode 10B, and the diaphragm 10C are stacked in one direction (e.g., the Y direction). In addition, the first electrode 10A is an example of the "electrode sheet" of this disclosure.

[0050] The first electrode 10A and the second electrode 10B have a sheet-like shape. The electrode body 10 is composed of an electrode plate assembly formed by winding the first electrode 10A and the second electrode 10B with one or more diaphragms 10C in between.

[0051] In this embodiment, the first electrode 10A is the positive electrode and the second electrode 10B is the negative electrode. However, it is also possible for the first electrode 10A to be the negative electrode and the second electrode 10B to be the positive electrode.

[0052] A separator 10C is disposed between the first electrode 10A and the second electrode 10B. The separator 10C enables ion exchange between the first electrode 10A and the second electrode 10B, and also separates the first electrode 10A and the second electrode 10B. The ions mentioned above are, for example, lithium ions. The separator 10C has electrical insulation properties.

[0053] Of the first electrode 10A, the second electrode 10B, and the diaphragm 10C, the diaphragm 10C is located on the innermost circumferential side centered on the winding axis α. Conversely, of the first electrode 10A, the second electrode 10B, and the diaphragm 10C, the diaphragm 10C is located on the outermost circumferential side centered on the winding axis α. The outer circumferential edge of the diaphragm 10C in the winding direction is fixed by a belt member 10D disposed on the outer circumferential surface of the diaphragm 10C.

[0054] The first electrode 10A includes a first current collector 11A and a first active material layer 12A. The second electrode 10B includes a second current collector 11B and a second active material layer 12B.

[0055] Figure 5 This is a cross-sectional view of the first electrode 10A and the first connector 90A. The first current collector 11A includes an insulating support layer 110, a first conductive layer 111, and a second conductive layer 112. The first electrode 10A also includes a protective portion 13. Furthermore, the first conductive layer 111 and the second conductive layer 112 are examples of the "conductive layers" of this disclosure.

[0056] The insulating support layer 110 is composed of a resin composition having electrical insulating properties. For example, the insulating support layer 110 is composed of a resin composition containing a polyester resin. The polyester resin is preferably, for example, polyethylene terephthalate. This allows for improved rigidity of the first current collector 11A while maintaining the electrical insulation properties of the insulating support layer 110. Furthermore, the insulating support layer 110 can be made thinner. The orthogonal direction DO, which is orthogonal to the thickness direction DT of the insulating support layer 110, is approximately parallel to the Z direction. Additionally, the material of the insulating support layer 110 is not limited to the examples described above. For example, the insulating support layer 110 can be cloth or paper.

[0057] The first conductive layer 111 is formed (in contact) with the insulating support layer 110 on one side in the thickness direction DT. Viewed from the insulating support layer 110, the first conductive layer 111 is located on the side of the winding axis α (i.e., the inner circumferential side). In addition, the first conductive layer 111 is provided on one side in the thickness direction DT, covering the entire surface of the coated portion 15a and the uncoated portion 15b, which will be described later.

[0058] The second conductive layer 112 is formed (in contact) with the insulating support layer 110 on the other side of the thickness direction DT. Viewed from the insulating support layer 110, the second conductive layer 112 is located on the side opposite to the winding axis α (i.e., the outer peripheral side). In addition, the second conductive layer 112 is provided on the other side of the thickness direction DT, covering the entire surface of the coated portion 15a and the uncoated portion 15b, which will be described later.

[0059] The first conductive layer 111 and the second conductive layer 112 are each composed of metal layers. The first conductive layer 111 and the second conductive layer 112 are each composed of a metal containing aluminum. Therefore, the first current collector 11A can be suitably used as a positive current collector. Alternatively, the first current collector 11A can be a negative current collector, and the first conductive layer 111 and the second conductive layer 112 can be made of a metal containing copper.

[0060] Multiple first connectors 90A are respectively joined to the first conductive layer 111 and the second conductive layer 112, for example, by ultrasonic welding. The multiple first connectors 90A extend from the insulating support layer 110 toward the Z1 side.

[0061] The first current collector 11A has surfaces 14a and 14b arranged in the thickness direction DT. Surface 14a is the surface of the first conductive layer 111 opposite to the insulating support layer 110. Surface 14b is the surface of the second conductive layer 112 opposite to the insulating support layer 110.

[0062] The first current collector 11A has a coated portion 15a on which the first active material layer 12A is coated and an uncoated portion 15b on which the first active material layer 12A is not coated. At least a portion of the uncoated portion 15b exposes the first current collector 11A. The uncoated portion 15b is located further Z1 than the coated portion 15a (the first connecting member 50A). Figure 3 The first active material layer 12A covers the surfaces 14a and 14b of the coating portion 15a in the first current collector 11A.

[0063] Each of the plurality of first connectors 90A includes a first foil portion 91 and a second foil portion 92. Viewed from the first conductive layer 111, the first foil portion 91 is located on the opposite side of the insulating support layer 110. The first foil portion 91 is bonded to the first conductive layer 111. The first foil portion 91 is connected to the first connecting member 50A (… Figure 3 The second foil portion 92 is located on the opposite side of the insulating support layer 110 when viewed from the second conductive layer 112. The second foil portion 92 is bonded to the second conductive layer 112.

[0064] The first foil portion 91 is disposed on the portion 14c of the surface 14a corresponding to the uncoated portion 15b. The first foil portion 91 is engaged with the portion 14c.

[0065] The second foil portion 92 is disposed on the portion 14d in the surface 14b corresponding to the uncoated portion 15b. The second foil portion 92 is engaged with the portion 14d. The portion 14d is disposed in the area that overlaps with the portion 14c in the Z direction.

[0066] The first foil portion 91 includes a lower portion 91a and an upper portion 91b. The lower portion 91a is disposed on the first electrode 10A. Specifically, the lower portion 91a is engaged with portion 14c. The upper portion 91b extends from the lower portion 91a (portion 14c) toward the Z1 side (first connecting member 50A). Figure 3 (Side) protrusion.

[0067] The second foil portion 92 includes a lower portion 92a and an upper portion 92b. The lower portion 92a is disposed on the first electrode 10A. Specifically, the lower portion 92a is engaged with portion 14d. The upper portion 92b extends from the lower portion 92a (portion 14d) toward the Z1 side (first connecting member 50A). Figure 3 (Side) protrusion.

[0068] The upper portion 91b is joined to the upper portion 92b. Specifically, the upper portions 91b and 92b are joined at a joint portion 93 on the Z1 side, which is closer to the first current collector 11A, for example by ultrasonic welding.

[0069] The first foil portion 91 (upper portion 91b) extends further towards the Z1 side than the upper end portion 92c (Z1-side end) of the second foil portion 92 (upper portion 92b). The joining portion 93 is the portion where the upper portion 92b joins the root portion on the Z2 side of the upper portion 91b. The joining portion 93 extends, for example, from the upper end portion 10E of the electrode body 10 towards the Z1 side. The upper end portion 10E of the electrode body 10 is the diaphragm 10C (… Figure 4 The upper end of the joint portion 93. In addition, the lower end of the joint portion 93 may be located, for example, further to the Z1 or Z2 side than the upper end portion 10E.

[0070] As described above, the length of the first foil portion 91 in the orthogonal direction DO (Z direction), which is orthogonal to the thickness direction DT, is longer than the length of the second foil portion 92 in the orthogonal direction DO. However, the shape of the first connector 90A is not limited to this. The length of the second foil portion 92 in the orthogonal direction DO may also be longer than the length of the first foil portion 91 in the orthogonal direction DO. Furthermore, the second foil portion 92 may be engaged with the first connecting member 50A, while the first foil portion 91 may not be engaged with the first connecting member 50A.

[0071] The first active material layer 12A includes an inner active material layer 121A and an outer active material layer 122A. The inner active material layer 121A is stacked on the first conductive layer 111. The outer active material layer 122A is stacked on the second conductive layer 112.

[0072] The upper edge of the first active material layer 12A is separated from each of the plurality of first connectors 90A. Specifically, the upper edge of the inner active material layer 121A is separated from the first foil portion 91 of each of the plurality of first connectors 90A. The upper edge of the outer active material layer 122A is separated from the second foil portion 92 of each of the plurality of first connectors 90A.

[0073] Diaphragm 10C is wound around axis α ( Figure 4 The membrane 10C is stacked radially on the first active material layer 12A, centered on the first active material layer 12A. The membrane 10C is also stacked radially on the outer active material layer 122A.

[0074] The protective part 13 is electrically insulating, for example, made of ceramic. The protective part 13 covers the upper part of the first active material layer 12A. The protective part 13 further covers the first current collector 11A between the first connector 90A and the first active material layer 12A.

[0075] The protective portion 13 includes an inner protective portion 131 and an outer protective portion 132. The inner protective portion 131 covers the upper part of the inner active material layer 121A. The inner protective portion 131 covers a first conductive layer 111 between the first foil portion 91 and the inner active material layer 121A. The outer protective portion 132 covers the upper part of the outer active material layer 122A. The outer protective portion 132 covers a second conductive layer 112 between the second foil portion 92 and the outer active material layer 122A.

[0076] Figure 6 This is a top view that schematically shows the surface of the first conductive layer 111. Furthermore, the structure of the second conductive layer 112 is the same as that of the first conductive layer 111. Therefore, the features of the first conductive layer 111 will be described in detail below as an example.

[0077] In conventional energy storage devices, when the insulating support layer bends, the conductive layer cannot follow the flexibility of the insulating support layer. Specifically, when the conductive layer and the insulating support layer bend together, gaps sometimes form between the metal particles constituting the conductive layer, sometimes resulting in cracks in the conductive layer. In this case, the insulating support layer is exposed due to the formation of cracks. As a result, it is believed that the organic support layer will expand or contract due to gas permeation into the exposed insulating support layer.

[0078] Therefore, in this embodiment, the first conductive layer 111 is formed of flake metal powder (flake metal particles) 113. Specifically, the first conductive layer 111 is formed by stacking flake metal powder 113 on top of each other. In addition, the flake metal powder 113 is formed, for example, from aluminum particles.

[0079] Flake metal powder refers to metal particles with an aspect ratio greater than that of ordinary metal powders (hereinafter referred to as non-flake metal powders), which are different from flake metal powders. Furthermore, in this specification, the maximum value of the diameter r of the metal powder as viewed from above (…) Figure 6 (middle length) divided by the thickness t of the metal powder (t is the vertical length) Figure 7 The value obtained by taking the maximum value of ) is defined as the aspect ratio. Furthermore, since non-flake metal powder is approximately spherical, its aspect ratio is approximately 1. Additionally, the maximum and minimum values ​​of the diameter r of the flake metal powder 113 ( Figure 6 The aspect ratios (length and width) of the flake metal powder 113 are tens of μm. The thickness t of the flake metal powder 113 is several μm. Therefore, the aspect ratio of the flake metal powder 113 is greater than 1 (e.g., 10). Furthermore, the diameter of the non-flake metal powder is several nm.

[0080] Figure 7 A schematic cross-sectional view of the first conductive layer 111 and the insulating support layer 110 is shown. Additionally, in Figure 7 In this context, the left and right directions are set as orthogonal directions DO, but the left and right directions can also be directions that are orthogonal to the orthogonal directions DO and DT respectively (i.e., the winding direction of the electrode body 10).

[0081] like Figure 7 As shown, the flake metal powder 113 consists of plate-shaped particles. Therefore, when the first electrode 10A is bent, even if gaps are formed between adjacent flake metal powders 113 in a direction intersecting (perpendicular) to the stacking direction (e.g., orthogonal direction DO), these gaps can be easily covered by the flake metal powders 113 stacked across each other. As a result, the exposure of the insulating support layer 110 due to cracks forming on the first conductive layer 111 can be suppressed.

[0082] Therefore, the expansion or contraction of the insulating support layer 110 caused by gas permeation can be suppressed. As a result, the peeling (detachment) of the first conductive layer 111 caused by the release of the gas between the insulating support layer 110 and the first conductive layer 111 can be suppressed.

[0083] like Figure 7 As shown, compared to non-flake metal powders, adjacent flake metal powders 113 in the stacking direction (thickness direction DT) are more likely to intersect (perpendicular to) each other in a direction that is perpendicular to the stacking direction. Figure 7 The orthogonal directions (DO) in the first conductive layer 111 are offset from each other. Therefore, pinholes are less likely to form on the first conductive layer 111.

[0084] <Manufacturing Method of Energy Storage Unit>

[0085] Figure 8 The manufacturing process is shown as an example of a method for manufacturing the energy storage unit 100.

[0086] In step S1, an insulating support layer 110 is prepared. Additionally, in step S1, a surface cleaning treatment of the insulating support layer 110 may be performed. Cleaning may include, for example, at least one of plasma treatment, corona treatment, UV treatment, static electricity removal treatment, adhesive roller treatment, and solvent treatment.

[0087] In step S2, a first conductive layer 111 and a second conductive layer 112 are formed on the insulating support layer 110. In step S3, an inner active material layer 121A is formed on the first conductive layer 111, and an outer active material layer 122A is formed on the second conductive layer 112. Furthermore, steps S1 to S3 are included in the process of forming the first electrode 10A.

[0088] In step S4, the second electrode 10B is formed. In step S5, the first electrode 10A, the second electrode 10B, and the diaphragm 10C are wound together. Furthermore, steps S1 to S5 are included in the process of forming the electrode body 10.

[0089] In step S6, the electrode body 10 formed by winding in step S5 is housed in the housing 20.

[0090] Figure 9 It means Figure 8 The diagram shows the process in step S2. In step S2, the first conductive layer 111 and the second conductive layer 112 are formed by electrostatic coating. Furthermore, the electrostatic coating in step S2 is performed in an atmospheric environment.

[0091] Specifically, paint particles 201 containing flake metal powder 113 are sprayed from a positively charged electrostatic spray gun 200 onto both surfaces of the insulating support layer 110. As a result, a first conductive layer 111 and a second conductive layer 112 are formed by stacking flake metal powder 113 on both surfaces of the insulating support layer 110.

[0092] The insulating support layer 110 is supplied by a negatively charged roller 202, passing through the area where paint particles 201 are sprayed by the electrostatic spray gun 200. Therefore, the insulating support layer 110 is negatively charged. As a result, paint particles 201 from the positively charged electrostatic spray gun 200 are sprayed onto the negatively charged insulating support layer 110.

[0093] Therefore, the paint particles 201 are electrostatically attracted by the insulating support layer 110, thus suppressing the decrease in the movement speed of the paint particles 201 during their movement from the electrostatic spray gun 200 to the insulating support layer 110. As a result, the paint particles 201 easily disperse on the surface of the insulating support layer 110. This allows the flake metal powder 113 to be easily oriented along the surface of the insulating support layer 110. Furthermore, Figure 9(+) indicates a positive charge, and (-) indicates a negative charge.

[0094] Alternatively, the flake metal powder 113 can be formed by pulverizing metal foil. Alternatively, the flake metal powder can be formed by rolling spherical particles, which are precursors produced by atomization, during the pulverization process.

[0095] As described above, in the above embodiment, the first conductive layer 111 and the second conductive layer 112 formed on the insulating support layer 110 are each formed of flake metal powder 113. This allows the formation of conductive layers in which the flake metal powder 113 is stacked in an alternating pattern. Consequently, the gaps between adjacent flake metal powders 113 can be covered by the flake metal powder 113 stacked across each other. This suppresses the exposure of the insulating support layer 110.

[0096] Furthermore, in the above embodiment, in the first electrode 10A constituting the wound electrode body 10, conductive layers (111, 112) are respectively disposed on the inner and outer peripheral sides of the insulating support layer 110. Here, since the electrode body 10 is wound, bending stress is easily applied to each of the first conductive layer 111 and the second conductive layer 112. Therefore, gaps are easily generated between adjacent flake metal powders 113. Therefore, using flake metal powder 113 is particularly effective in suppressing the exposure of the insulating support layer 110 in the wound electrode body 10.

[0097] <Variation Example>

[0098] In the above embodiments, an example is shown where the conductive layer formed on the insulating support layer 110 is formed solely of flake metal powder 113, but this disclosure is not limited thereto. Figure 10 In the example shown, a conductive layer 300, consisting of a conductive layer 111 and a conductive layer 310, is formed on the insulating support layer 110. The conductive layer 310 is disposed on the side opposite to the insulating support layer 110 relative to the conductive layer 111. The conductive layer 310 is formed of non-flake metal powder 311. As described above, the aspect ratio of the non-flake metal powder 311 is smaller than that of the flake metal powder 113. Additionally, on the conductive layer 112 side, it can also be combined with... Figure 10 Similarly constituted. In Figure 10 In the example shown, conductive layer 111 and conductive layer 310 are examples of the "first metal layer" and "second metal layer" of this disclosure, respectively.

[0099] The non-flake metal powder 311 is formed into a spherical shape, so that adjacent non-flake metal powders 311 on the outermost surface form a recess 312 between each other. As a result, the first active material layer 12A enters the recess 312, so the first active material layer 12A can be more stably fixed to the conductive layer 300 through the anchoring effect.

[0100] Alternatively, the conductive layer 300 can be formed by depositing or sputtering a conductive layer 310 on the conductive layer 111 after the conductive layer 111 is formed on the insulating support layer 110 by electrostatic coating or the like.

[0101] exist Figure 11 In the example shown, a conductive layer 400, consisting of a conductive layer 111 and a conductive layer 310, is formed on the insulating support layer 110. The conductive layer 310 is disposed on the insulating support layer 110 side relative to the conductive layer 111. Additionally, a conductive layer 112 side may also be disposed with... Figure 11 It is constructed in the same way.

[0102] Here, since the flake metal powder 113 extends along the insulating support layer 110, the bending stiffness of the conductive layer 111 is higher than that of the conductive layer 310. Therefore, the conductive layer 310 with lower bending stiffness is disposed near the insulating support layer 110, and the conductive layer 310 is covered by the conductive layer 111. As a result, the insulating support layer 110 can be easily bent, and cracks formed on the conductive layer 310 can be covered by the conductive layer 111 (flake metal powder 113).

[0103] Alternatively, the conductive layer 400 can be formed by forming the conductive layer 310 on the insulating support layer 110 by electrostatic coating or the like, after the conductive layer 310 is formed on the conductive layer 310.

[0104] In the above embodiments, an example is shown where the first conductive layer 111 and the second conductive layer 112 have the same structure, but this disclosure is not limited thereto. One side of the conductive layer may have... Figure 7 , Figure 10 and Figure 11 In any of the structures described, the conductive layer on the other side can have Figure 7 , Figure 10 and Figure 11 The structure is different from the conductive layer on the aforementioned side. Alternatively, a conductive layer may be formed only on the surface of one side of the insulating support layer 110. Furthermore, a conductive layer formed of flake metal powder may be formed on the Z (DO) direction end face of the insulating support layer 110.

[0105] In the above embodiments, an example of forming a conductive layer by electrostatic coating using an electrostatic spray gun is shown, but the present disclosure is not limited thereto. For example, a coating containing flake metal powder can be applied to the insulating support layer 110 using a positively charged roller coating method. Alternatively, the insulating support layer 110 can be impregnated in a coating containing flake metal powder filled in a positively charged container.

[0106] In the above embodiments, an example is shown where the first electrode 10A comprises a conductive layer formed of flake metal powder, but the present disclosure is not limited thereto. Based on this, or instead of the first electrode 10A, the second electrode 10B may comprise a conductive layer formed of flake metal powder (e.g., copper powder).

[0107] In the above embodiments, an example of forming a conductive layer by electrostatic coating is shown, but the present disclosure is not limited thereto. For example, paint particles containing flake metal powder can be sprayed from the spray gun onto the insulating support layer while the spray gun and the insulating support layer are uncharged.

[0108] In the above embodiments, an example of housing the electrode body 10 within the housing 20 is shown, but this disclosure is not limited thereto. For example, the electrode body 10 can be housed (sealed) by a laminated film. In this case, the laminated film is an example of the "housing" of this disclosure.

[0109] The structures of the above-described embodiments and variations can be combined with each other.

[0110] Embodiments of the present invention have been described, but should be considered illustrative rather than restrictive in all respects. The scope of the invention is defined by the claims, including all equivalents thereof and any modifications within that scope.

Claims

1. An energy storage unit comprising an electrode body and a housing for receiving the electrode body, The electrode body includes electrode plates. The electrode sheet has an insulating support layer and a conductive layer formed on the insulating support layer. The conductive layer is formed from flake metal powder.

2. The energy storage unit according to claim 1, The electrode body is a wound electrode body formed by winding the electrode sheet around the winding axis. The conductive layer is disposed in the electrode sheet at least at one of the inner and outer peripheral sides of the insulating support layer.

3. The energy storage unit according to claim 1 or 2, The conductive layer comprises a first metal layer and a second metal layer stacked together. The first metal layer is formed from the flake metal powder. The second metal layer is formed from non-flake metal powder. The aspect ratio of the non-flake metal powder is smaller than that of the flake metal powder.

4. A method for manufacturing an energy storage unit, comprising a step of forming an electrode body and a step of housing the electrode body in a housing, The process of forming the electrode body includes a process of preparing an insulating support layer and a process of forming a conductive layer by laminating flake metal powder on the insulating support layer.

5. The method for manufacturing the energy storage unit according to claim 4, The process of forming the conductive layer is a process of electrostatically coating the flake metal powder onto the insulating support layer.

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