Power storage device and method for manufacturing power storage device

Abstract

This power storage device comprises: an electrode group 2 in which an electrode plate 11 and a separator 14 are laminated; and a current collector plate 5. The electrode plate 11 includes: a plate-shaped current collector 34; an adhesive layer 38 laminated in a region including an end part on at least one surface of the current collector 34; and an electrode mixture layer 36 laminated in a region excluding a region overlapping with the end part of the current collector 34 in the adhesive layer 38. The end part of the current collector 34 is bent and joined to the current collector plate 5.

Description

Power storage device and method for manufacturing power storage device

[0001] The present disclosure relates to a power storage device and a method for manufacturing a power storage device.

[0002] Conventionally, batteries in which an electrode group and an electrolytic solution are housed in an outer can are known. Regarding such a power storage device, Patent Document 1 describes a method of forming a flat surface by bending an exposed portion of a core body of an electrode, that is, an exposed portion of a current collector, and welding a current collector plate to the flat surface.

[0003] Japanese Patent Application Laid-Open No. 2008-166030

[0004] Generally, since the end portion of a current collector has low strength and stiffness, it is not easy to bend it into a target shape or maintain the shape after bending. Therefore, there is room for improving the connection reliability between the current collector and the current collector plate.

[0005] The present disclosure has been made in view of such circumstances, and one of the objects thereof is to provide a technique for improving the connection reliability between a current collector and a current collector plate.

[0006] One aspect of the present disclosure is a power storage device. The power storage device includes an electrode group in which electrode plates and a separator are stacked, and a current collector plate. The electrode plate includes a plate-shaped current collector, an adhesive layer laminated in a region including an end portion on at least one surface of the current collector, and an electrode mixture layer laminated in a region of the adhesive layer excluding a region overlapping the end portion of the current collector. The end portion of the current collector is bent and joined to the current collector plate.

[0007] Another aspect of the present disclosure is a method for manufacturing a power storage device. The manufacturing method includes: laminating an adhesive layer in a region including an end portion on at least one surface of a plate-shaped current collector; laminating an electrode mixture layer in a region of the adhesive layer excluding a region overlapping the end portion of the current collector to produce an electrode plate; stacking the electrode plate and a separator to produce an electrode group; bending the end portion of the current collector in the electrode group; and joining the bent end portion of the current collector to the current collector plate.

[0008] Any combination of the above components, and conversions of the expressions of the present disclosure between methods, devices, systems, and the like are also effective as aspects of the present disclosure.

[0009] According to this disclosure, the reliability of the connection between the current collector and the current collector plate can be improved.

[0010] This is a cross-sectional view of an energy storage device according to an embodiment. This is a perspective view of the electrode group. This is a schematic cross-sectional view showing an enlarged view of the joint between the electrode group and the current collector plate. Figures 4(A), 4(B), 4(C), and 4(D) are schematic diagrams showing the manufacturing process of the electrode plate and the energy storage device. Figures 5(A), 5(B), and 5(C) are schematic diagrams showing the manufacturing process of the electrode plate and the energy storage device.

[0011] The present disclosure will be described below with reference to the drawings, based on preferred embodiments. The embodiments are illustrative and not limiting, and not all features or combinations thereof described in the embodiments are necessarily essential to the present disclosure. The same or equivalent components, members, and processes shown in each drawing are denoted by the same reference numerals, and redundant descriptions are omitted where appropriate. The scale and shape of each part shown in each drawing are set for convenience to facilitate explanation and are not to be interpreted restrictively unless otherwise specified. Furthermore, where terms such as "first," "second," etc. are used in this specification or claims, unless otherwise specified, these terms do not indicate any order or importance, but are used to distinguish one configuration from another. In addition, some components that are not important for explaining the embodiments are omitted in each drawing.

[0012] Figure 1 is a cross-sectional view of the energy storage device 1 according to an embodiment. Figure 2 is a perspective view of the electrode group 2. Figure 2 shows the state before the end of the current collector 34 is bent. Also, the adhesive layer 38 is not shown in Figures 1 and 2. The energy storage device 1 is, for example, a rechargeable secondary battery such as a lithium-ion battery, a nickel-metal hydride battery, or a nickel-cadmium battery, or a capacitor such as an electric double-layer capacitor. The energy storage device 1 comprises the electrode group 2, a first current collector plate 4, a second current collector plate 6, and an outer casing 8.

[0013] Electrode group 2 is, for example, cylindrical, and has a wound structure in which a strip-shaped first electrode plate 10 and a strip-shaped second electrode plate 12 are stacked with a strip-shaped separator 14 in between, and wound in a spiral shape. Therefore, the first electrode plate 10 and the second electrode plate 12 are arranged alternately in the radial direction Y of electrode group 2, and the separator 14 is interposed between two adjacent electrode plates in the radial direction Y, with each electrode plate and separator 14 being stacked. In electrode group 2, the longitudinal direction of each electrode plate and separator 14 is the winding direction Z, and the short direction of each electrode plate and separator 14, in other words, the width direction, is the axial direction X.

[0014] In this embodiment, the first electrode plate 10 is the positive electrode plate, and the second electrode plate 12 is the negative electrode plate. Alternatively, the first electrode plate 10 may be the negative electrode plate and the second electrode plate 12 may be the positive electrode plate. Furthermore, in the following description, when the polarity of the electrode plates is not distinguished, the first electrode plate 10 and the second electrode plate 12 will be collectively referred to as electrode plate 11, and the first current collector plate 4 and the second current collector plate 6 will be collectively referred to as current collector plate 5. The separator 14 is, for example, made of polypropylene, polyethylene, or the like, a microporous film having ion permeability and insulating properties.

[0015] The electrode plate 11 comprises a plate-shaped current collector 34, an adhesive layer 38 (see Figure 3), which will be described later, and an electrode mixture layer 36. The structure of the electrode plate 11 will be described in detail later. The electrode plate 11 has an exposed portion 42 at its short-side end, where the adhesive layer 38 is laminated on the current collector 34, but the electrode mixture layer 36 is not laminated. The exposed portion 42 of the first electrode plate 10 and the exposed portion 42 of the second electrode plate 12 protrude in opposite directions in the axial direction X. The ends of each current collector 34, i.e., the exposed portions 42, are bent in the radial direction Y of the electrode group 2. In this embodiment, the exposed portions 42 are bent toward the winding center of the electrode group 2. Since the electrode group 2 has a structure in which the electrode plates 11 are wound, multiple exposed portions 42 are arranged in the radial direction Y of the electrode group 2. Note that multiple exposed portions 42 may be bent at predetermined intervals in the winding direction Z.

[0016] The bent exposed portion 42 of the first electrode plate 10 is joined to the first current collector plate 4 by ultrasonic welding, laser welding, or the like. This electrically connects the current collector 34 of the first electrode plate 10 to the first current collector plate 4. The bent exposed portion 42 of the second electrode plate 12 is joined to the second current collector plate 6 by ultrasonic welding, laser welding, or the like. This electrically connects the current collector 34 of the second electrode plate 12 to the second current collector plate 6. By bending the exposed portion 42, the contact area between the current collector 34 and the current collector plate 5 can be increased. Therefore, the current collector 34 can be connected to the current collector plate 5 more reliably and stably. The first current collector plate 4 and the second current collector plate 6 are arranged so as to sandwich the electrode group 2 in the axial direction X.

[0017] The electrode group 2, to which the first current collector plate 4 and the second current collector plate 6 are joined, is housed in an outer container 8 along with an electrolyte (not shown). The outer container 8 is, for example, a bottomed cylindrical metal container. The first current collector plate 4 is positioned on the opening side of the outer container 8. The second current collector plate 6 is positioned on the bottom side of the outer container 8. A sealing body 20 is fitted into the opening of the outer container 8. A gasket 22 is provided between the outer container 8 and the sealing body 20. This seals the electrode group 2, the first current collector plate 4, the second current collector plate 6, and the electrolyte inside the outer container 8.

[0018] The sealing body 20 includes a filter 24, a lower valve body 26, an upper valve body 28, an insulating member 30, and a cap 32. Each component of the sealing body 20 has, for example, a disc shape or a ring shape. In addition, each component except the insulating member 30 is electrically connected to one another. The filter 24 has an opening 24a and covers the opening of the outer can 8. The lower valve body 26 and the upper valve body 28 cover the opening of the outer can 8 and close the opening 24a. The lower valve body 26 and the upper valve body 28 are connected at their respective central portions, with the insulating member 30 interposed between their respective peripheral portions. When the internal pressure of the outer can 8 rises due to heat generation caused by an internal short circuit or the like, for example, the lower valve body 26 may rupture. As a result, the upper valve body 28 bulges towards the cap 32 and separates from the lower valve body 26. Consequently, the electrical connection between the lower valve body 26 and the upper valve body 28 is interrupted. A cap 32 is placed over the outside of the upper valve body 28.

[0019] One end of the lead 16 is joined to the first current collector plate 4 by welding or the like. The other end of the lead 16 is joined to the filter 24 by welding or the like. The cap 32 is electrically connected to the filter 24 to form the first electrode terminal. The second current collector plate 6 is joined to the bottom of the outer casing 8 by welding or the like. Therefore, the outer casing 8 forms the second electrode terminal. The structure of the energy storage device 1 can be changed as appropriate. For example, the outer casing 8 may be rectangular or coin-shaped. The outer casing 8 may also be an outer casing made of laminated sheet. The electrode group 2 may be laminated instead of wound.

[0020] Next, the structure of the electrode plate 11 will be described in detail. Figure 3 is a schematic cross-sectional view showing an enlarged view of the joint between the electrode group 2 and the current collector plate 5. Note that only a portion of the electrode plate 11 is shown in Figure 3. The electrode plate 11 comprises a current collector 34, an adhesive layer 38, and an electrode mixture layer 36. The current collector 34 is made of metal foil or the like. In the case of a typical lithium-ion secondary battery, the current collector 34 is made of aluminum foil or the like if it is the positive electrode, and copper foil or the like if it is the negative electrode.

[0021] The adhesive layer 38 is laminated on the surface of the current collector 34. For example, the adhesive layer 38 can be laminated on the surface of the current collector 34 by applying the adhesive constituting the adhesive layer 38 to the surface of the current collector 34. The adhesive layer 38 is laminated in a region including the axial end X on at least one surface of the current collector 34. In this embodiment, the adhesive layer 38 is laminated over the entire surface of both main surfaces of the current collector 34. The adhesive layer 38 is interposed between the current collector 34 and the electrode mixture layer 36 to bond them together. The thickness of the adhesive layer 38 is, for example, less than 2% of the thickness of the electrode mixture layer 36, and is, for example, 0.1 μm or more and 10 μm or less.

[0022] Examples of adhesives included in the adhesive layer 38 include fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF); polyacrylonitrile (PAN); polyimide resins; acrylic resins; polyolefin resins; and synthetic rubbers such as styrene-butadiene rubber (SRB). The adhesive content in the adhesive layer 38 is, for example, 5% by mass or more and 60% by mass or less of the total mass of the adhesive layer 38.

[0023] The adhesive layer 38 may contain a conductive material. This reduces the interfacial resistance between the current collector 34 and the adhesive layer 38, and the interfacial resistance between the electrode mixture layer 36 and the adhesive layer 38. Therefore, the resistance between the current collector 34 and the electrode mixture layer 36 can be reduced. Examples of conductive materials included in the adhesive layer 38 include carbon black (CB), acetylene black (AB), Ketjenblack, and carbon-based particles such as graphite. The content of the conductive material in the adhesive layer 38 is, for example, 40% by mass or more and 95% by mass or less of the total mass of the adhesive layer 38. The volume resistivity of the adhesive layer 38 is, for example, 10 ４ It is less than or equal to Ωcm.

[0024] The adhesive layer 38 may also contain an insulating filler. This allows the insulating filler in the adhesive layer 38 to act as a resistive component in the event of an internal short circuit caused by conductive foreign matter, thereby suppressing an increase in the short-circuit current between the positive and negative electrodes.

[0025] The electrode mixture layer 36 is laminated on a portion of the surface of the adhesive layer 38. In this embodiment, the electrode mixture layer 36 is laminated in the area of ​​the adhesive layer 38 excluding the area that overlaps with the axial X end of the current collector 34. As a result, the exposed portion 42 described above is formed at the end of the electrode plate 11 in the axial X direction. In the exposed portion 42, the adhesive layer 38 is laminated on the current collector 34, but the electrode mixture layer 36 is not laminated on the adhesive layer 38. The electrode mixture layer 36 may be laminated on the entire surface of the adhesive layer 38 excluding the exposed portion 42, or it may be laminated on a portion of the adhesive layer 38 excluding the exposed portion 42.

[0026] The electrode mixture layer 36 contains an electrode active material. In the case of a typical lithium-ion secondary battery, the electrode active material is lithium cobalt oxide or lithium iron phosphate for the positive electrode, and graphite for the negative electrode. As an example, the electrode mixture layer 36 is composed of a dry electrode mixture. For example, the electrode mixture layer 36 mainly consists of a dry electrode mixture. That is, the content of the dry electrode mixture relative to the total mass of the electrode mixture layer 36 is 50% by mass or more.

[0027] Dry electrode mixtures contain electrode active material and, if necessary, binders, conductive materials, solvents, etc. Examples of binders include PTFE and PVdF. Examples of conductive materials include graphite, CB, and AB. When the dry electrode mixture is used as the negative electrode, the solvent may be water, alcohols, N-methylpyrrolidone (NMP), toluene, dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), etc. When the dry electrode mixture is used as the positive electrode, the solvent may be amine-based solvents, ether-based solvents, ketone-based solvents, ester-based solvents, amide-based solvents, etc. The total content of binders and solvents in the dry electrode mixture is, for example, 5% by mass or less, 1% by mass or less, or substantially 0% based on the total mass of the dry electrode mixture.

[0028] When the electrode mixture layer 36 is composed of a dry electrode mixture, for example, the electrode mixture layer 36 can be laminated onto the surface of the adhesive layer 38 by pressing a pre-formed dry electrode mixture sheet onto the surface of the adhesive layer 38. An electrode mixture layer 36 composed of a dry electrode mixture is generally difficult to fix to the current collector 34. In contrast, by interposing the adhesive layer 38 between the current collector 34 and the electrode mixture layer 36, the electrode mixture layer 36 can be more stably fixed to the current collector 34 by the anchoring effect of the adhesive layer 38.

[0029] The electrode mixture layer 36 may be a wet electrode mixture in which the content of the binding component is more than 5% by mass of the total mass of the electrode mixture. In this case, the electrode mixture layer 36 can be laminated on the surface of the adhesive layer 38 by applying the wet electrode mixture to the surface of the adhesive layer 38.

[0030] In this embodiment, a portion of the electrode mixture layer 36 penetrates the adhesive layer 38 and contacts the current collector 34. This reduces the resistance between the current collector 34 and the electrode mixture layer 36. For example, the current collector 34, adhesive layer 38, and electrode mixture layer 36 are stacked in this order to form a laminate. Before winding the laminate, the laminate is pressurized in the stacking direction of each layer, compressing each layer. This causes the electrode mixture layer 36 to locally penetrate the adhesive layer 38 and contact the current collector 34. This pressurization can be performed, for example, by passing the laminate between a pair of rolls. The pressure applied to the laminate is, for example, 50 MPa or more in contact surface pressure, and may be 85 MPa or more. The portion of the electrode mixture layer 36 that contacts the current collector 34 may be evenly distributed in the extending direction of the electrode mixture layer 36.

[0031] Furthermore, as described above, in this embodiment, the end portion of the current collector 34, i.e., the exposed portion 42, is bent in the radial direction Y of the electrode group 2 and joined to the current collector plate 5. The exposed portion 42 does not have an electrode mixture layer 36 extending over it, and has a structure in which only the current collector 34 and the adhesive layer 38 are laminated. Since the adhesive layer 38 has toughness, it is possible to easily maintain the shape and orientation of the current collector 34 when it is bent. For this reason, the stability of the electrical connection between the current collector 34 and the current collector plate 5 can be improved when joining the end portion of the current collector 34 to the current collector plate 5 and after joining.

[0032] Next, the manufacturing methods for the electrode plates 11 and the energy storage device 1 will be described. Figures 4(A) to 4(D) and 5(A) to 5(C) are schematic diagrams showing the manufacturing process of the electrode plates 11 and the energy storage device 1. Note that only a portion of the electrode plates 11 are shown in Figures 5(A) to 5(C).

[0033] First, as shown in Figure 4(A), a plate-shaped current collector 34 is prepared. For example, the current collector 34 is a long, strip-shaped metal foil. Then, an adhesive layer 38 is laminated on at least one surface of the current collector 34, in a region that includes a preliminary exposed portion 42a which will eventually become the exposed portion 42. In this embodiment, as an example, the adhesive is applied to the entire surface of both main surfaces of the current collector 34 to form the adhesive layer 38.

[0034] Next, as shown in Figure 4(B), an electrode mixture layer 36 is laminated on a portion of the surface of the adhesive layer 38. In this embodiment, the electrode mixture layer 36 is laminated in the area of ​​the adhesive layer 38 excluding the leading exposed portion 42a of the current collector 34. As an example, the electrode mixture layer 36 is laminated on both main surfaces of the current collector 34. In addition, multiple electrode mixture layers 36 are laminated on the surface of the adhesive layer 38 at predetermined intervals. For example, two electrode mixture layers 36 are arranged in the short-side direction A of the current collector 34. The gap between adjacent electrode mixture layers 36 in the short-side direction A overlaps with the leading exposed portion 42a. Furthermore, each electrode mixture layer 36 is laminated over substantially the entire length direction B of the current collector 34. Each electrode mixture layer 36 can be formed, for example, by passing a current collector 34 on which an adhesive layer 38 is laminated and a plurality of strip-shaped dry electrode mixture sheets between a pair of rolls 40, and pressing each dry electrode mixture sheet onto the adhesive layer 38.

[0035] Next, the laminate 44 consisting of the current collector 34, adhesive layer 38, and electrode mixture layer 36 is pressed in the stacking direction of each layer, compressing each layer. As a result, as shown in Figure 4(C), the distance between the electrode mixture layer 36 and the current collector 34 is reduced. Also, a portion of the electrode mixture layer 36 penetrates the adhesive layer 38 and comes into contact with the current collector 34. Through these steps, a plurality of strip-shaped electrode plates 11 connected to each other at the exposed portion 42 are produced. The pressurization of the laminate 44 may be performed by a pair of rolls 40 for pressing the dry electrode mixture sheet onto the adhesive layer 38, or by another pressurizing device.

[0036] Next, as shown in Figure 4(D), the current collector 34 and adhesive layer 38 are cut in the longitudinal direction B between adjacent electrode mixture layers 36. In other words, the exposed portion 42 connecting the multiple electrode plates 11 is cut, dividing them into individual strip-shaped electrode plates 11. This cutting can be performed using a known cutting device such as a cutter or a laser cutting device. When dividing into multiple electrode plates 11, the adhesive layer 38 can suppress the scattering of dust, burrs, spatter, etc. that may occur when the current collector 34 is cut by cutting the current collector 34 whose surface is covered with the adhesive layer 38. Furthermore, the adhesive layer 38 can also suppress the generation of dust and other particles themselves. This prevents impurities from adhering to the electrode mixture layers 36, etc., and improves the performance of the energy storage device 1. Alternatively, the multiple electrode mixture layers 36 may be stacked at predetermined intervals in the longitudinal direction B of the current collector 34, and the current collector 34 and adhesive layer 38 may be cut in the short direction A between adjacent electrode mixture layers 36.

[0037] Next, the two electrode plates 11 and the two strip-shaped separators 14 are stacked alternately and wound in a spiral shape. This creates a wound electrode group 2, as shown in Figure 5(A). Of the two electrode plates 11, one is designated as the first electrode plate 10 and the other as the second electrode plate 12. The short direction A of the current collector 34 coincides with the axial direction X of the electrode group 2, and the long direction B of the current collector 34 coincides with the winding direction Z of the electrode group 2. Therefore, the exposed portion 42 of the current collector 34 is positioned at the end of the electrode group 2 in the axial direction X.

[0038] Next, as shown in Figure 5(B), the ends of each current collector 34 in the electrode group 2, that is, the exposed portions 42 of each electrode plate 11, are bent in the radial direction Y of the electrode group 2. This bending process can be carried out by pressing a known processing tool 46, such as a roller, against the exposed portions 42 of each electrode plate 11. Because the adhesive layer 38 has toughness, when the exposed portions 42 are bent, it is possible to suppress excessive bending, insufficient bending, or the exposed portions 42, which have low strength, from returning to their original shape after being bent. As a result, each current collector 34 can be more reliably joined to the current collector plate 5, and the state in which the current collector 34 is joined to the current collector plate 5 can be stably maintained.

[0039] Next, as shown in Figure 5(C), the current collector plate 5 is pressed against the bent exposed portion 42 of each electrode plate 11. Then, each exposed portion 42 and the current collector plate 5 are joined to each other by ultrasonic welding, laser welding, or the like. The adhesive layer 38 disappears due to heating during the joining process. Therefore, the current collector 34 is directly connected to the current collector plate 5.

[0040] Subsequently, the electrode group 2, to which the first current collector plate 4 and the second current collector plate 6 are joined, is housed in the outer container 8 along with the electrolyte. Then, processes such as joining the second current collector plate 6 to the outer container 8, joining the first current collector plate 4 to the sealing body 20, and fitting the sealing body 20 into the outer container 8 are performed to obtain the energy storage device 1. Note that the order of processing such as joining each part, housing in the outer container 8, and fitting the sealing body 20 can be changed as appropriate. For example, if the sealing body 20 is provided with an injection port, the electrolyte may be injected into the outer container 8 after the sealing body 20 has been fitted into the opening of the outer container 8.

[0041] As described above, in the electrode plate 11 of this embodiment, the electrode mixture layer 36 is laminated on a part of the surface of the adhesive layer 38. This allows the current collector 34 and the electrode mixture layer 36 to be stably fixed by the adhesive layer 38, and also reduces the accuracy of the position and dimensions of the electrode mixture layer 36 relative to the adhesive layer 38. Therefore, the manufacturing process of the electrode plate 11 can be simplified.

[0042] Furthermore, in this embodiment, the adhesive layer 38 is laminated over the entire surface of the current collector 34. This further simplifies the manufacturing process of the electrode plate 11 compared to the case where the adhesive layer 38 is laminated over a portion of the current collector 34.

[0043] Furthermore, in the present embodiment, the laminate 44 including the current collector 34, the adhesive layer 38, and the electrode mixture layer 36 is pressed, whereby a part of the electrode mixture layer 36 penetrates the adhesive layer 38 and is in contact with the current collector 34. This can suppress an increase in resistance between the current collector 34 and the electrode mixture layer 36 caused by providing the adhesive layer 38, and consequently suppress a decrease in performance of the power storage device 1. In addition, the adhesive layer 38 contains a conductive material. This can further reduce the resistance between the current collector 34 and the electrode mixture layer 36. Therefore, the performance of the power storage device 1 can be further improved.

[0044] Furthermore, in the present embodiment, the adhesive layer 38 is laminated on the exposed portion 42 of the current collector 34 for electrical connection to the current collector plate 5. The exposed portion 42 is bent in the radial direction Y of the electrode group 2 and joined to the current collector plate 5. This can improve the connection reliability between the current collector 34 and the current collector plate 5, and improve the performance of the power storage device 1. In addition, in the manufacturing process of the electrode plate 11, a plurality of electrode mixture layers 36 are laminated on the surface of the adhesive layer 38 at predetermined intervals, and the current collector 34 and the adhesive layer 38 are cut between adjacent electrode mixture layers 36, thereby manufacturing a plurality of electrode plates 11. This allows the adhesive layer 38 to suppress the generation of dust and the like accompanying cutting of the current collector 34, as well as scattering of the generated dust and the like. Therefore, the performance of the power storage device 1 can be improved.

[0045] The structure of the electrode plate 11 described above may be provided in only one of the first electrode plate 10 and the second electrode plate 12. The other electrode plate 11 may have a conventional structure.

[0046] The embodiments of this disclosure have been described in detail above. The embodiments described above are merely examples of how to implement this disclosure. The content of the embodiments does not limit the technical scope of this disclosure, and many design changes, such as changes, additions, and deletions of components, are possible as long as they do not depart from the spirit of the invention as defined in the claims. A new embodiment with design changes will have the combined effects of both the embodiment and the variation. In the embodiments described above, the content in which such design changes are possible is emphasized with notations such as "of this embodiment" or "in this embodiment," but design changes are also permitted even if there are no such notations. Furthermore, any combination of components included in each embodiment is also valid as an embodiment of this disclosure. The hatching applied to the cross-section in the drawings does not limit the material of the object to which the hatching is applied.

[0047] Embodiments may be specified by the items described below. [Item 1] A power storage device (1) comprising: an electrode group (2) in which electrode plates (10, 11, 12) and a separator (14) are stacked; and current collector plates (4, 5, 6), wherein the electrode plates (10, 11, 12) each include: a plate-shaped current collector (34); an adhesive layer (38) stacked on a region including an end (42) on at least one surface of the current collector (34); and an electrode mixture layer (36) stacked on a region of the adhesive layer (38) excluding the region overlapping the end (42) of the current collector (34), and the end (42) of the current collector (34) is bent and joined to the current collector plates (4, 5, 6). [Item 2] The power storage device (1) according to Item 1, wherein a part of the electrode mixture layer (36) penetrates the adhesive layer (38) and contacts the current collector (34). [Item 3] The power storage device (1) according to Item 1 or 2, wherein the adhesive layer (38) contains a conductive material. [Item 4] A method for manufacturing a power storage device (1), comprising: forming an adhesive layer (38) stacked on a region including an end (42) on at least one surface of a plate-shaped current collector (34), forming an electrode mixture layer (36) stacked on a region of the adhesive layer (38) excluding the region overlapping the end (42) to produce an electrode plate (10, 11, 12), stacking the electrode plate (10, 11, 12) and a separator (14) to produce an electrode group (2), bending the end (42) of the current collector (34) in the electrode group (2), and joining the bent end (42) of the current collector (34) to a current collector plate (4, 5, 6). [Item 5] The manufacturing method according to Item 4, comprising pressing a laminate (44) of the current collector (34), the adhesive layer (38), and the electrode mixture layer (36) in the lamination direction of each layer.

[0048] The present disclosure can be used for a power storage device and a method for manufacturing a power storage device.

[0049] 1: power storage device, 2: electrode group, 4: first current collector plate, 5: current collector plate, 6: second current collector plate, 10: first electrode plate, 11: electrode plate, 12: second electrode plate, 14: separator, 34: current collector, 36: electrode mixture layer, 38: adhesive layer, 42: exposed portion, 44: laminate.

Claims

1. An energy storage device comprising an electrode group in which electrode plates and separators are laminated, and a current collector plate, wherein the electrode plate has a plate-shaped current collector, an adhesive layer laminated in a region including the end on at least one surface of the current collector, and an electrode mixture layer laminated in a region of the adhesive layer excluding the region overlapping with the end of the current collector, and the end of the current collector is bent and joined to the current collector plate.

2. The energy storage device according to claim 1, wherein a portion of the electrode mixture layer penetrates the adhesive layer and contacts the current collector.

3. The energy storage device according to claim 1 or 2, wherein the adhesive layer includes a conductive material.

4. A method for manufacturing an energy storage device, comprising: laminating an adhesive layer in a region including the end on at least one surface of a plate-shaped current collector; laminating an electrode mixture layer in the region of the adhesive layer excluding the region overlapping with the end of the current collector to produce an electrode plate; laminating the electrode plate and a separator to produce an electrode group; bending the end of the current collector in the electrode group; and joining the bent end of the current collector to the current collector plate.

5. The manufacturing method according to claim 4, comprising applying pressure to the laminate of the current collector, the adhesive layer, and the electrode mixture layer in the lamination direction of each layer.

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