JP6641978B2 - Method of manufacturing electrode assembly and electrode assembly - Google Patents

Description

  The present invention relates to a method for manufacturing an electrode assembly and an electrode assembly.

  A power storage device such as a lithium ion battery includes an electrode assembly in which a plurality of electrodes are stacked. Each electrode has a tab, and in manufacturing the electrode assembly, the tabs of the stacked electrodes are welded. The welding is performed by irradiating an energy beam to the end face of the tabs in a stacked state. (See, for example, Patent Document 1).

JP-A-2002-313309

  At the time of welding, the end face of the tab is irradiated with an energy beam in a state where the conductive member is disposed on the stacked tabs, and at this time, a part of the conductive member is heated together with the end face of the tab. In this case, a part of the energy to be used for welding the end face of the tab is used to heat a part of the conductive member, so that the energy required for welding increases.

  An object of one aspect of the present invention is to provide a method for manufacturing an electrode assembly and an electrode assembly capable of reducing the energy required for welding the stacked tabs.

  A method of manufacturing an electrode assembly according to one aspect of the present invention is a method of manufacturing an electrode assembly having a plurality of electrodes each including a tab, and includes a tab laminate having a plurality of tabs stacked, and a tab laminate. A step of preparing a conductive member disposed thereon, and irradiating an energy beam to an end face of the tab laminate extending along the lamination direction of the tab laminate, thereby welding a weld inward from the end face of the tab laminate. And forming the conductive member in the preparing step, when viewed from the stacking direction of the tab stack, in a plane orthogonal to the stacking direction of the tab stack, from the end face of the tab stack. A first portion disposed in a first plane located inside, and a second portion located in a second plane located inside the first plane; Of the area of the first portion occupying the first plane If it is less than the ratio of the area of the second portion occupying the second plane has a cross-sectional shape orthogonal to the stacking direction of the tab laminate.

  In the above-described method for manufacturing an electrode assembly, an end face of the tab laminate is irradiated with an energy beam in a state where the conductive member is arranged on the tab laminate, and a welded portion is formed inside the end face of the tab laminate. When the weld is formed in this manner, a part of the energy to be used for welding the end face of the tab laminate is used to heat a part of the conductive member. In the above-described method for manufacturing an electrode assembly, the conductive member is, when viewed from the stacking direction of the tab laminate, a first plane located perpendicular to the stacking direction of the tab laminate and located inside the end face of the tab laminate. And a second portion located in a second plane located inside the first plane, so that the first portion of the conductive member Will be heated. Here, when viewed from the laminating direction of the tab laminate, the conductive member is such that the proportion of the area of the first portion occupying the first plane is greater than the proportion of the area of the second portion occupying the second plane. It has a small cross-sectional shape perpendicular to the laminating direction of the tab laminate. For this reason, for example, the conductive member has a smaller ratio of the area of the first portion occupying the first plane and the area of the second portion occupying the second plane than the case where the conductive member has only the same cross-sectional shape. The energy used to heat one part (that is, a part of the conductive member) can be reduced. Therefore, the energy required for welding the stacked tabs can be reduced.

  In the preparing step, since the first portion has the cutout portion, the ratio of the area of the first portion to the first plane is larger than the ratio of the area of the second portion to the second plane. It may be smaller. For example, in this manner, the ratio of the area of the first portion to the first plane in the conductive member can be made smaller than the ratio of the area of the second portion to the second plane.

  In the preparing step, the conductive member has a plate shape, and the thickness of at least a part of the first part is smaller than the thickness of the second part, so that the area of the first part occupying the first plane May be smaller than the ratio of the area of the second portion to the second plane. For example, in this manner, the ratio of the area of the first portion to the first plane in the conductive member can be made smaller than the ratio of the area of the second portion to the second plane.

  In the preparing step, when viewed from the stacking direction of the tab laminate, the tip of the first portion of the conductive member may be located at the end face of the tab laminate, and may be in contact with the tab laminate. Thereby, a welded portion can be formed in a state where a load is applied to each tab in the laminating direction at the end face of the tab laminate.

  An electrode assembly according to one aspect of the present invention is an electrode assembly having a plurality of electrodes each including a tab, wherein the tab assembly has a plurality of stacked tabs and a tab stack in a stacking direction of the tab stack. A conductive member disposed on the body, the tab laminate has a welded portion located inside from the end face of the tab laminate extending along the lamination direction of the tab laminate, the conductive member, A first portion disposed in a first plane located inside from an end face of the tab laminate in a plane orthogonal to the stack direction of the tab laminate, when viewed from a lamination direction of the tab laminate; A second portion disposed in a second plane located inside the first plane; and the conductive member has a ratio of an area of the first portion occupying the first plane to the second plane. How to laminate the tab laminate, which is smaller than the proportion of the area of the second portion occupied Having a cross-section perpendicular to.

  The electrode assembly has a welded portion formed inside from the end face of the tab laminate, and the conductive member disposed on the tab laminate has an area of the first portion occupying the first plane. It has a cross-sectional shape that is smaller than the ratio of the area of the second portion to the second plane and that is orthogonal to the stacking direction of the tab stack. Therefore, for example, when a weld is formed by irradiating an energy beam as described above, the energy required for welding can be reduced.

  In the electrode assembly, since the first portion has the cutout portion, the ratio of the area of the first portion to the first plane is larger than the ratio of the area of the second portion to the second plane. It may be smaller.

  According to one aspect of the present invention, there is provided a method of manufacturing an electrode assembly and an electrode assembly capable of reducing energy required for welding stacked tabs.

1 is an exploded perspective view of a power storage device including an electrode assembly according to an embodiment. FIG. 2 is a cross-sectional view of the power storage device taken along line II-II in FIG. 1. It is a perspective view of an electrode assembly concerning an embodiment. FIG. 4 is a diagram schematically illustrating a part of the electrode assembly of FIG. 3. FIG. 5 is a sectional view of the electrode assembly taken along line VV of FIG. 4. FIG. 5 is a sectional view of the electrode assembly taken along the line VI-VI in FIG. 4. FIG. 7 is a sectional view of the electrode assembly taken along line VII-VII of FIG. 4. It is a figure showing one process of a manufacturing method of an electrode assembly concerning an embodiment. It is a figure which shows typically a part of electrode assembly concerning a 1st modification. FIG. 10 is a sectional view of the electrode assembly taken along line XX of FIG. 9. It is a figure which shows typically a part of electrode assembly concerning a 2nd modification. FIG. 12 is a sectional view of the electrode assembly taken along line XII-XII of FIG. 11. FIG. 14 is a diagram schematically illustrating a part of an electrode assembly according to a third modification. FIG. 14 is a sectional view of the electrode assembly taken along the line XIV-XIV of FIG. 13.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same reference numerals will be used for the same or equivalent elements, and redundant description will be omitted. In the drawings, an XYZ rectangular coordinate system is shown as necessary. The Z-axis direction is, for example, a vertical direction, and the X-axis direction and the Y-axis direction are, for example, a horizontal direction.

  FIG. 1 is an exploded perspective view of a power storage device including the electrode assembly according to the first embodiment. FIG. 2 is a cross-sectional view of the power storage device taken along line II-II in FIG. The power storage device 1 shown in FIGS. 1 and 2 is a nonaqueous electrolyte secondary battery such as a lithium ion secondary battery or an electric double layer capacitor.

  As shown in FIGS. 1 and 2, the power storage device 1 includes, for example, a hollow case 2 having a substantially rectangular parallelepiped shape, and an electrode assembly 3 housed in the case 2. The case 2 is formed of a metal such as aluminum, for example. The case 2 has a main body 2a opened on one side and a lid 2b for closing the opening of the main body 2a. An insulating film (not shown) is provided on the inner wall surface of the case 2. For example, a non-aqueous (organic solvent) electrolyte is injected into the case 2. In the electrode assembly 3, the positive electrode active material layer 15 of the positive electrode 11, the negative electrode active material layer 18 of the negative electrode 12, and the separator 13, which will be described later, are porous, and the pores are impregnated with the electrolytic solution. . A positive electrode terminal 5 and a negative electrode terminal 6 are arranged separately from each other on the lid 2 b of the case 2. The positive terminal 5 is fixed to the case 2 via an insulating ring 7, and the negative terminal 6 is fixed to the case 2 via an insulating ring 8.

  The electrode assembly 3 is a laminated electrode assembly. The electrode assembly 3 includes a plurality of positive electrodes 11 (electrodes), a plurality of negative electrodes 12 (electrodes), and a bag-shaped separator 13 disposed between the positive electrode 11 and the negative electrode 12. The separator 13 houses, for example, the positive electrode 11. The plurality of positive electrodes 11 and the plurality of negative electrodes 12 are alternately stacked with the positive electrode 11 accommodated in the separator 13 with the separator 13 interposed therebetween.

  The positive electrode 11 has a metal foil 14 made of, for example, an aluminum foil, and a positive electrode active material layer 15 formed on both surfaces of the metal foil 14. The metal foil 14 of the positive electrode 11 includes a rectangular main body 14a and a rectangular tab 14b protruding from one end of the main body 14a. The positive electrode active material layer 15 is a porous layer formed including a positive electrode active material and a binder. The positive electrode active material layer 15 is formed by supporting the positive electrode active material on at least the central portion of the main body 14a on both surfaces of the main body 14a.

  Examples of the positive electrode active material include a composite oxide, lithium metal, sulfur, and the like. The composite oxide contains, for example, at least one of manganese, nickel, cobalt, and aluminum, and lithium. Here, as an example, the tab 14b does not carry a positive electrode active material. However, the active material may be carried on the base end portion of the tab 14b on the side of the main body 14a.

  The tab 14b extends upward from the upper edge of the main body 14a, and is connected to the positive electrode terminal 5 via the current collector plate 16. The current collecting plate 16 is disposed between the tab 14b and the positive terminal 5. The current collector 16 is, for example, formed in the shape of a rectangular flat plate from the same material as the metal foil 14 of the positive electrode 11. The plurality of stacked tabs 14b are arranged between the current collector 16 and the protective plate 23 (conductive member) thinner than the current collector 16 (see FIG. 3). The protection plate 23 is formed, for example, in the shape of a rectangular flat plate from the same material as the metal foil 14 of the positive electrode 11.

  The negative electrode 12 has a metal foil 17 made of, for example, a copper foil, and a negative electrode active material layer 18 formed on both surfaces of the metal foil 17. Like the metal foil 14 of the positive electrode 11, the metal foil 17 of the negative electrode 12 includes a rectangular main body 17a and a rectangular tab 17b protruding from one end of the main body 17a. The negative electrode active material layer 18 is formed on both surfaces of the main body 17a, at least in a central portion of the main body 17a, in which the negative electrode active material is supported. The negative electrode active material layer 18 is a porous layer formed including a negative electrode active material and a binder.

  Examples of the negative electrode active material include graphite, highly oriented graphite, mesocarbon microbeads, carbon such as hard carbon and soft carbon, alkali metals such as lithium and sodium, metal compounds, SiOx (0.5 ≦ x ≦ 1.5 ) And boron-added carbon. Here, as an example, the tab 17b does not carry the negative electrode active material. However, an active material may be carried on the base end portion of the tab 17b on the main body 17a side.

  The tab 17b extends upward from the upper edge of the main body 17a and is connected to the negative electrode terminal 6 via the current collector plate 19. The current collector 19 is disposed between the tab 17b and the negative electrode terminal 6. The current collector 19 is, for example, formed in the shape of a rectangular flat plate from the same material as the metal foil 17 of the negative electrode 12. The stacked plurality of tabs 17b are arranged between the current collector 19 and the protective plate 27 (conductive member) thinner than the current collector 19 (see FIG. 3). The protection plate 27 is, for example, formed in the shape of a rectangular flat plate from the same material as the metal foil 17 of the negative electrode 12.

  The separator 13 houses the positive electrode 11. The separator 13 has a rectangular shape when viewed from the laminating direction of the positive electrode 11 and the negative electrode 12. For example, the separator 13 is formed in a bag shape by welding a pair of long sheet-like separator members to each other. Examples of the material of the separator 13 include a porous film made of a polyolefin resin such as polyethylene (PE) and polypropylene (PP), and a woven or nonwoven fabric made of polypropylene, polyethylene terephthalate (PET), methylcellulose, and the like.

  FIG. 3 is a perspective view of the electrode assembly according to the embodiment. The electrode assembly 3 includes a plurality of positive electrodes 11 and a plurality of negative electrodes 12 stacked on each other with a separator 13 interposed therebetween. Each of the plurality of positive electrodes 11 includes a main body 14a extending in the XY plane, and a tab 14b protruding from one end of the main body 14a in the X-axis direction. Each of the plurality of negative electrodes 12 includes a main body 17a extending in the XY plane, and a tab 17b projecting from one end of the main body 17a in the X-axis direction. The tabs 14b and 17b are laminated on each other to form tab laminated bodies 21 and 25, respectively. That is, the electrode assembly 3 includes a tab laminate 21 having a plurality of tabs 14b laminated in the Z-axis direction, and a tab laminate 25 having a plurality of tabs 17b laminated in the Z-axis direction. The tab laminates 21 and 25 are arranged apart from each other in the Y-axis direction.

  The tab laminate 21 includes end surfaces 21a, 21b, and 21c of the tab laminate 21 extending along the lamination direction (Z-axis direction) of the tab laminate 21. The end surfaces 21a and 21b are surfaces sandwiching the tab laminate 21, and the end surface 21c is a surface connecting the end surfaces 21a and 21b. That is, the end faces 21a and 21b are arranged on opposite sides of the tab laminate 21. The end surfaces 21a and 21b are surfaces along the XZ plane. The end surface 21c is a surface inclined with respect to the XY plane such that the thickness of the tab laminate 21 decreases toward the tip of the tab laminate 21.

  The tab laminate 21 is disposed between the current collector 16 and the protection plate 23 in the Z-axis direction. That is, the current collector 16 is arranged on the tab laminate 21 in the Z-axis direction. The protection plate 23 is disposed on the tab laminate 21 on the opposite side of the current collector 16 from the tab laminate 21. The protection plate 23 is not in contact with the current collector 16, and the protection plate 23 and the current collector 16 are separated from each other with the tab laminate 21 interposed therebetween in the laminating direction. The tab laminate 21 is thicker than the protection plate 23, and the current collector 16 is thicker than the protection plate 23.

  The length of the current collector 16 in the Y-axis direction is larger than the length of the tab laminate 21 in the Y-axis direction (the distance between the end faces 21a and 21b). In the Y-axis direction, the position of the outer end of the current collector plate 16 in the Y-axis direction matches the position of the end of the main body 14a in the Y-axis direction. The length of the protection plate 23 in the Y-axis direction is substantially the same as the length of the tab laminate 21 in the Y-axis direction.

  The tab laminate 21 has welds W located inside the end faces 21a and 21b of the tab laminate 21, respectively. The welded portion W extends to the inside of the current collector 16 and the protection plate 23 adjacent to the end faces 21a and 21b. In the end faces 21a and 21b, the length of the welded portion W in the X-axis direction is preferably substantially equal to the length of the protection plate 23 in the X-axis direction, or shorter than the length of the protection plate 23 in the X-axis direction. Thereby, even when the tab 14b of the tab laminate 21 is displaced in the X-axis direction (for example, when there is a displacement due to tolerance), the welded portion W can be formed stably. When the length of the welded portion W in the X-axis direction is substantially equal to the length of the protective plate 23 in the X-axis direction, the welded portion W may protrude outside the protective plate 23 in the X-axis direction due to positional displacement. When the length of the welded portion W in the X-axis direction is longer than the length of the protection plate 23 in the X-axis direction, the welded portion W protrudes outside the protection plate 23 in the X-axis direction. Even in those cases, it is possible to form the welded portion W.

  Similarly, the tab laminate 25 includes end surfaces 25a, 25b, and 25c of the tab laminate 25 that extend along the lamination direction (Z-axis direction) of the tab laminate 25. The end surfaces 25a and 25b are surfaces sandwiching the tab laminate 25, and the end surface 25c is a surface connecting the end surfaces 25a and 25b. That is, the end faces 25a and 25b are arranged on opposite sides of the tab laminate 25. The end surfaces 25a and 25b are surfaces along the XZ plane. The end surface 25c is a surface inclined with respect to the XY plane so that the thickness of the tab laminate 25 decreases toward the tip of the tab laminate 25.

  The tab laminate 25 is arranged between the current collector 19 and the protection plate 27 in the Z-axis direction. In the Z-axis direction, the current collector 19 is arranged on the tab laminate 25. The protection plate 27 is disposed on the tab laminated body 25 on the opposite side of the current collecting plate 19 across the tab laminated body 25. The protection plate 27 is not in contact with the current collecting plate 19, and is separated from the protection plates 27 and 29 by sandwiching the tab stack 25 in the stacking direction. The tab laminate 25 is thicker than the protection plate 27, and the current collector 19 is thicker than the protection plate 27.

  The length of the current collector plate 19 in the Y-axis direction is larger than the length of the tab laminate 25 in the Y-axis direction (the distance between the end surfaces 25a and 25b). In the Y-axis direction, the position of the outer end of the current collector plate 19 in the Y-axis direction matches the position of the end of the main body 17a in the Y-axis direction. The length of the protection plate 27 in the Y-axis direction is substantially the same as the length of the tab laminate 25 in the Y-axis direction.

  The tab laminate 25 has a welded portion W located inside each of the end faces 25a and 25b of the tab laminate 25. The end face 25b of the tab laminate 25 faces the end face 21b of the tab laminate 21. Therefore, the end faces 21a, 21b, 25a, 25b of the tab laminates 21, 25 are arranged along the Y-axis direction. The welded portion W extends to the inside of the current collector 19 and the protection plate 27 adjacent to the end faces 25a and 25b. In the end faces 25a and 25b, the length of the welded portion W in the X-axis direction is preferably substantially equal to the length of the protection plate 27 in the X-axis direction, or shorter than the length of the protection plate 27 in the X-axis direction. Thus, even when the tab 17b of the tab laminate 25 is displaced in the X-axis direction (for example, when there is a displacement due to tolerance), the welded portion W can be formed stably. When the length of the welded portion W in the X-axis direction is substantially equal to the length of the protection plate 27 in the X-axis direction, the welded portion W may protrude outside the protection plate 27 in the X-axis direction due to positional displacement. When the length of the welded portion W in the X-axis direction is longer than the length of the protection plate 27 in the X-axis direction, the welded portion W protrudes outside the protection plate 27 in the X-axis direction. Even in those cases, it is possible to form the welded portion W.

  One feature of the present embodiment lies in the shape of the protection plates 23 and 27. Here, an example of the shape of the protection plate 27 will be described in detail with reference to FIGS. Since the shape of the protection plate 23 can be described in the same manner as the shape of the protection plate 27, detailed description is omitted.

  FIG. 4 is a diagram schematically illustrating a part of the electrode assembly in FIG. 3, and is an enlarged view of the periphery of the tab laminate 25. FIG. 5 is a sectional view taken along line VV of FIG. FIG. 6 is a sectional view taken along the line VI-VI in FIG. FIG. 7 is a sectional view taken along line VII-VII in FIG. FIG. 7 is also a diagram illustrating a plane orthogonal to the stacking direction of the tab stacks 21 and 25. As described above, the protection plate 27 is disposed on the tab laminate 25. In the present embodiment, the protection plate 27 includes first portions 27a and 27b and a second portion 27c.

  The first portions 27a and 27b are located inside the end surfaces 25a and 25b of the tab laminated body 25 on a plane orthogonal to the laminating direction when viewed from the laminating direction (Z-axis direction) of the tab laminated body 25. Are arranged in the first plane S1. The first plane S1 is, for example, rectangular. The length of the first plane S1 in the X-axis direction is equal to or shorter than the length of the protection plate 27 in the X-axis direction. The length of the first plane S1 in the Y-axis direction may be shorter than the length of the protection plate 27 in the Y-axis direction. In the Y-axis direction, the edge of the first plane S1 may coincide with the end faces 25a, 25b.

  The second portion 27c is located inside the first planes S1 and S1 on a plane orthogonal to the stacking direction when viewed from the stacking direction (Z-axis direction) of the tab stack 25. In the plane S2. The second plane S2 is, for example, rectangular. The length of the second plane S2 in the X-axis direction is equal to or shorter than the length of the protection plate 27 in the X-axis direction. The length of the second plane S2 in the Y-axis direction may be shorter than the length of the protection plate 27 in the Y-axis direction.

  The length of the first plane S1 in the X-axis direction may be equal to or different from the length of the second plane S2 in the X-axis direction. The length of the first plane S1 in the Y-axis direction may be equal to or different from the length of the second plane S2 in the Y-axis direction. When the length of the first plane S1 and the length of the second plane S2 in the X-axis direction and the Y-axis direction are both equal, the area of the first plane S1 is equal to the area of the second plane S2. .

  In the present embodiment, in a plane orthogonal to the laminating direction of the tab laminated body 25, the protection plate 27 has a second plane S2 in which the area ratio of the first portion 27a to the first plane S1 occupies the second plane S2. It has a cross-sectional shape smaller than the area ratio of the first portion 27b. The protection plate 27 may have the above-described cross-sectional shape at at least one position in the stacking direction of the tab stack 25.

  Specifically, in the example shown in FIGS. 4 and 7, the first portion 27 a of the protection plate 27 has a cutout portion C. Such a protection plate 27 can be obtained, for example, by punching a flat plate. Punching, pressing, or the like may be used for the processing. In this example, the first portion 27a has a plurality of notches C. The notches C are formed at intervals in the X-axis direction. The notch C has, for example, a rectangular shape when viewed from the Z-axis direction, and also has a rectangular shape when viewed from the Y-axis direction. It can be said that the first portion 27a has a comb shape. Since the first portion 27a has the notch C, the ratio of the area of the first portion 27a to the first plane S1 is smaller than that in the case where the first portion 27a does not have the notch C. Can be smaller. Like the first portion 27a, the first portion 27b also has a notch C. Therefore, the ratio of the area of the first portion 27b to the second plane S2 can be reduced as compared with the case where the first portion 27b does not have the cutout portion C. In this example, the length in the Z-axis direction of the notch C in the first portion 27a is the same as the length of the other portion in the first portion 27a. That is, when the electrode assembly 3 is viewed in a plan view (when viewed in the negative direction of the Z axis), the surface of the tab laminate 25 is exposed at the portion where the cutout portion C is located. However, the length of the notch C in the Z-axis direction may be shorter than the length of the other portions. In that case, when the electrode assembly 3 is viewed in a plan view, the surface of the tab laminate 25 is not exposed at the portion where the cutout portion C exists. That is, the first portion 27a also covers the surface of the tab laminate at the portion where the cutout portion C is located.

  The second portion 27c has no notch C. For this reason, since the first portions 27a and 27b have the cutout portions C, the ratio of the area of the first portions 27a and 27b to the first plane S1 is increased by the second ratio to the second plane S2. It becomes smaller than the ratio of the area of the portion 27c.

  When viewed from the stacking direction of the tab laminate 25 (Z-axis direction), the tips of the first portions 27a and 27b in the Y-axis direction are located at the end faces 25a and 25b of the tab laminate 25, respectively. And is in contact with the tab laminate 25.

  The cross-sectional view shown in FIG. 5 is a cross-sectional view of a portion where the notch C is not provided in the first portion 27a of the protection plate 27 disposed on the tab laminate 25. As shown in FIG. 5, the welded portion W is located inside from the end faces 25 a and 25 b of the tab laminate 25. The length (weld depth) of the welded portion W inward from the end faces 25a, 25b increases from the protective plate 27 side to the current collector plate 19 side. The welded portion W is formed into a shape corresponding to the shape of the molten pool formed around the energy beam B by irradiation of an energy beam B (see FIG. 8) described later. The molten pool is formed so as to taper inward from the surface of the irradiation target of the energy beam B in the irradiation direction of the energy beam B, for example. The shape of the welded portion W shown in FIG. 5 is a shape when the energy beam B is irradiated from an obliquely upward direction of the tab laminate 25, where the Z-axis positive direction is the upward direction. The welding portion W is also formed on the current collector 19. Further, the welded portion W is also formed on the first portions 27a and 27b of the protection plate 27.

  The cross-sectional view shown in FIG. 6 is a cross-sectional view of a portion of the first portion 27a of the protection plate 27 disposed on the tab laminate 25, where the cutout portion C is provided. Also in this portion, the welded portion W is located inside from the end faces 25a and 25b of the tab laminate 25. Further, the welded portion W is also located on the current collector 19. In the example shown in FIG. 6, the welding depth of the welded portion W formed inside from the end faces 25a and 25b is larger than the welded depth of the welded portion W shown in FIG. This is because the first portion 27a of the protection plate 27 does not exist in the portion shown in FIG. 6, and much of the energy given by the irradiation of the energy beam B is used for heating the end surfaces 25a and 25b. Thereby, the end surfaces 25a and 25b of the tab laminate 25 can be welded more reliably. In the example shown in FIG. 6, the welded portion W formed on the current collector 19 is also larger than the welded portion W shown in FIG.

  In the above, with reference to FIGS. 4 to 7, the welded portion W located inside from the end surfaces 25 a and 25 b of the tab laminate 25 has been described. The same applies to the welded portion W located inside from the end faces 21a and 21b of the tab laminate 21, so that the description thereof is omitted.

  FIG. 8 is a view illustrating one process of a method for manufacturing an electrode assembly according to the embodiment. The electrode assembly 3 shown in FIG. 3 is manufactured by, for example, the following method.

(Preparation process for tab laminate)
First, a plurality of tab laminates 21 and 25 are prepared. FIG. 8A is a diagram schematically illustrating the tab laminates 21 and 25 viewed from the X-axis direction, and FIG. 8B is a diagram schematically illustrating the tab laminates 25 viewed from the Y-axis direction. is there. For example, first, the tab laminated bodies 21 and 25 are formed by laminating the tabs 14b and 17b on the current collector plates 16 and 19, respectively. Then, the protection plates 23 and 27 are mounted on the tab laminates 21 and 25, respectively. The tab laminates 21 and 25 are pressed by the jig via the protective plates 23 and 27, for example, but need not be pressed.

(Welded part forming process)
Next, the energy beam B is applied to the end face 25a of the tab laminate 25. The energy beam B is irradiated from the irradiation device 30 toward the end surface 25a of the tab stack 25. The irradiation device 30 is a scanner head including, for example, a lens and a galvanomirror. A beam generating device is connected to the scanner head via a fiber. The irradiation device 30 may be configured by a refraction type optical system such as a prism or a diffractive optical system such as a diffractive optical element (DOE). The energy beam B is, for example, a laser beam or an electron beam. The irradiation of the energy beam B is performed in the atmosphere of the inert gas G supplied from the nozzle 32.

  The energy beam B is applied to the end face 25a of the tab stack 25 while the tab stack 25 is pressed in the Z-axis direction via the current collector 19 and the protection plate 27 by a jig, for example. As described above, the tips of the first portions 27a and 27b in the Y-axis direction are located on the end surfaces 25a and 25b of the tab laminate 25, respectively, and are in contact with the tab laminate 25. As a result, in the tab laminated bodies 21 and 25, a load is applied to the tabs 14b and 17b on the end faces 21a, 21b, 25a and 25b. That is, the irradiation of the energy beam B to the end face 25a of the tab laminate 25 is performed in a state where a load is applied to the tab 17b on the end face 25a.

  The energy beam B is scanned on the end surface 25a of the tab laminate 25 along a direction (X-axis direction) crossing the Z-axis direction. In the embodiment, scanning is performed along the X-axis direction while displacing the energy beam B in the Z-axis direction. For example, scanning is performed along the X-axis direction while the energy beam B is reciprocated (wobbled) in the Z-axis direction. The amount of displacement of the irradiation spot of the energy beam B in the Z-axis direction is larger than the thickness of the tab laminate 25. The irradiation spot of the energy beam B moves from the position P1 on the axis along the X-axis direction to the position P2 on the end face 25a of the tab laminate 25. For example, the positions P1 and P2 are located at the center of the end surface 25a of the tab laminate 25 in the Z-axis direction. The energy beam B is scanned, for example, by moving the center point along the X-axis direction on the end surface 25a of the tab stack 25 and rotating the irradiation spot of the energy beam B on the XZ plane about the center point. It is preferable that the diameter of rotation is larger than the thickness of the tab laminate 25 because the current collector plate 19 and the first portion 27a of the protection plate 27 can be welded together with the end face 25a of the tab laminate 25. In addition, the energy beam B may not be applied to the portion of the end surface 25 a of the tab laminate 25 on the side of the protection plate 27, and the remaining portion of the end surface 25 a of the tab stack 25 may be not irradiated with the energy beam B. In this case, the welded portion W is not formed on the remaining portion of the end surface 25a of the tab laminate 25 on the current collector plate 19 side. However, since the welding portion W extends in the direction of irradiation of the energy beam B inside the end face 25a of the tab laminate 25, the welding portion W extends in the thickness direction of the tab laminate 25 inside the tab laminate 25. Will do. The plurality of tabs 17b and the current collecting plate 19 can be welded by causing the welding portion W to reach the current collecting plate 19.

  By irradiating the energy beam B as described above, as described above with reference to FIGS. 5 and 6, the welded portion W is formed inside the end surface 25 a of the tab laminate 25.

  Subsequently, the end face 21b of the tab laminate 21 is also irradiated with the energy beam B to form a welded portion W inside the end face 21b. Similarly, the energy beam B is applied to the end face 25b of the tab laminate 25 and the tab 21a of the tab laminate 21 to form a welded portion W inside the end faces 25b and 21a.

  Through the above steps, the electrode assembly 3 is manufactured. Thereafter, the electrode assembly 3 obtained by bending the tab laminates 21 and 25 is accommodated in the case 2, and the power storage device 1 can be manufactured.

  As described above, in the manufacturing method of the electrode assembly of the embodiment, the end faces 21a, 21b, 25a, 25a, of the tab laminates 21, 25 are arranged in a state where the protection plates 23, 27 are disposed on the tab laminates 21, 25. The energy beam B is applied to 25b, and a welded portion W is formed inside the end surfaces 21a, 21b, 25a, 25b of the tab laminates 21, 25. When the welded portion W is formed in this manner, a part of the energy to be used for welding the end faces 21a, 21b, 25a, 25b of the tab laminates 21, 25 heats a part of the protection plates 23, 27. Would be used for Here, in the manufacturing method of the electrode assembly according to the embodiment, when the protection plates 23 and 27 are viewed from the stacking direction (the Z-axis direction) of the tab stacks 21 and 25, the protection plates 23 and 27 A first portion (27a, 27b, etc.) arranged in a first plane S1 located on the inner side from the end faces 21a, 21b, 25a, 25b of the tab laminates 21, 25 on a plane orthogonal to the first direction; Since it includes the second portion (27c or the like) arranged in the second plane S2 located inside the plane S1, the first portion of the protection plates 23 and 27 is heated. . Here, when viewed from the stacking direction of the tab laminates 21 and 25, the protective plates 23 and 27 have the second ratio that the area ratio of the first portion occupying the first plane S1 occupies the second plane S2. Has a cross-sectional shape smaller than the ratio of the area of the portion. Therefore, for example, the protection plates 23 and 27 have only the same cross-sectional shape in which the ratio of the area of the first portion to the first plane S1 and the ratio of the area of the second portion to the second plane S2 are the same. The first portion (that is, a part of the protection plates 23 and 27) is heated more than in the case (for example, in the case where each ratio has the same cross-sectional shape at any position in the stacking direction of the tab laminates 21 and 25). Energy used for the above can be reduced. Therefore, it is possible to reduce the energy required for welding the tab laminates 21 and 25.

  For example, the protection plates 23 and 27 do not have the first portion, and the ratio of the area of the first portion to the first plane S1 and the ratio of the area of the second portion to the second plane S2 are as follows. However, the case where the same is true at any position in the stacking direction of the tab laminates 21 and 25 will be described. In this case, even when a part of the energy of the irradiated energy beam B is used for heating the protection plates 23 and 27, the output of the energy beam B is set to be relatively large in order to secure the welding depth of the welding portion W. It is possible to do. When irradiating the energy beam B having such a large output, for example, a design is made so that the current collector plates 16 and 19 are not excessively heated and penetrated or distorted. On the other hand, according to the manufacturing method of the electrode assembly according to the embodiment, the energy required for welding can be reduced, so that the output of the energy beam B can be set smaller. Therefore, the degree of freedom in design is improved. Further, since the output of the energy beam B can be reduced, it is possible to reduce the cost of equipment necessary for the irradiation of the energy beam.

  In the step of preparing the tab laminate, the first portion (27a, 27b, etc.) may have the notch C. In this manner, the ratio of the area of the first portion occupying the first plane S1 in the protection plates 23 and 27 can be made smaller than the ratio of the area of the second portion occupying the second plane S2. it can.

  In addition, in the tab laminate preparing step, when viewed from the lamination direction of the tab laminates 21 and 25, the distal ends of the first portions (27a and 27b, etc.) of the protection plates 23 and 27 have tabs in the Y-axis direction. It is located on the end face of the laminated bodies 21 and 25 and is in contact with the tab laminated bodies 21 and 25. Thereby, the welded portion W can be formed in a state where a load is applied to each of the tabs 14b and 17b in the stacking direction (Z-axis direction) on the end surfaces 21a, 21b, 25a and 25b of the tab stacks 21 and 25.

  In addition, the electrode assembly 3 described above with reference to FIGS. 3 to 5 includes the first portions of the protection plates 23 and 27 together with portions inside the end surfaces 21 a, 21 b, 25 a and 25 b of the tab laminates 21 and 25. Although the welded portions W are also formed on the portions (27a, 27b, etc.), the protection plates 23, 27 are such that the ratio of the area of the first portion to the first plane S1 is smaller than that of the second plane S2. It has a cross-sectional shape smaller than the ratio of the area of the second portion occupied. Therefore, for example, when the welding portion W is formed by irradiating the energy beam B as described above, the energy required for welding can be reduced.

  Specifically, in the electrode assembly 3, since the first portions (27a, 27b, etc.) have the cutouts C, the ratio of the area of the first portion to the first plane S1 is reduced by the second portion. Is smaller than the ratio of the area of the second portion to the plane S2.

  Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the invention.

(First Modification)
For example, in the above-described embodiment, an example has been described in which the notch portion C has a rectangular shape when viewed from the Z-axis direction, and also has a rectangular shape when viewed from the Y-axis direction. In the assembly, the notch C may have another shape. FIG. 9 is a diagram schematically showing a part of an electrode assembly according to such a modification. FIG. 10 is a cross-sectional view of the electrode assembly taken along line XX of FIG. FIG. 10 is also a diagram illustrating a plane orthogonal to the stacking direction of the tab stacks 21 and 25. In this example, the protection plate 37 disposed on the tab laminate 25 includes first portions 37a and 37b and a second portion 37c, and the first portions 37a and 37b Have. The cutout portions C of the first portions 37a and 37b have a triangular shape when viewed from the Z-axis direction, and also have a triangular shape when viewed from the Y-axis direction.

  9 and 10, the ratio of the area of the first portions 37a and 37b to the first plane S1 is larger than the ratio of the area of the first portion 37b to the second plane S2. small. Therefore, the energy required for welding the tab laminate 25 can be reduced. The same applies to the tab laminate 21.

(Second Modification)
Further, in the electrode assembly, the protection plate may not have the notch. For example, when the thickness of at least a part of the first portion of the protection plate is smaller than the thickness of the second portion, the ratio of the area of the first portion to the first plane is reduced to the second plane. It can also be smaller than the ratio of the area of the second portion occupied. FIG. 11 is a diagram schematically illustrating a part of an electrode assembly according to such a modification. FIG. 12 is a sectional view of the electrode assembly taken along the line XII-XII of FIG. FIG. 12 also shows a plane orthogonal to the stacking direction of the tab stacks 21 and 25. In this example, the protection plate 47 arranged on the tab laminate 25 includes first portions 47a and 47b and a second portion 47c. The first portions 47a and 47b have ends 47a1 and 47b1 in the Y-axis direction and other portions 47a2 and 47b2 located inside the ends 47a1 and 47b1. In the first portions 47a and 47b, the thickness (length in the Z-axis direction) of the end portions 47a1 and 47b1 is smaller than the thickness of the other portions 47a2 and 47b2. The thickness of the other portions 47a2 and 47b2 may be the same as the thickness of the second portion 47c.

  Also in the configuration shown in FIGS. 11 and 12, the cross-sectional shape of the protection plate 47 at a position where the ends 47a1 and 47b1 are not located in the stacking direction of the tab stack 25 is the first shape occupying the first plane S1. The ratio of the area of the portions 47a and 47b is smaller than the ratio of the second portion 47c occupying the second plane S2. Therefore, the energy required for welding the tab laminate 25 can be reduced. The same applies to the tab laminate 21.

(Third Modification)
Alternatively, the configuration shown in FIG. 13 may be employed. In this example, the protection plate 57 disposed on the tab laminate 25 includes first portions 57a and 57b and a first portion 57b. The thickness of the first portions 57a and 57b gradually decreases toward the outside in the Y-axis direction.

  FIG. 14 is a sectional view of the electrode assembly taken along the line XIV-XIV of FIG. FIG. 14 is also a diagram showing a plane orthogonal to the laminating direction of the tab laminates 21 and 25. Also in the configuration shown in FIG. 13 and FIG. 14, the protection plate 57 has a structure in which the ratio of the area of the first portions 57a and 57b occupying the first plane S1 to the area of the second portion 57c occupying the second plane S2. Has a cross-sectional shape smaller than the ratio of Therefore, the energy required for welding the tab laminate 25 can be reduced. The same applies to the tab laminate 21.

  The embodiment described above can be described, for example, as follows. That is, the method for manufacturing an electrode assembly according to the embodiment is a method for manufacturing an electrode assembly having a plurality of electrodes each including a tab, wherein the tab stack having a plurality of tabs stacked, and the tab stack Preparing a conductive member disposed on a body, and irradiating an energy beam to an end face of the tab stack extending along a stacking direction of the tab stack, thereby forming an end face of the tab stack. Forming a welded portion from the inside of the tub laminate, wherein in the preparing step, the conductive member includes a first cross section (for example, a plane parallel to the end face) along an end face of the tab laminate. And a second portion including a second cross section (for example, a plane parallel to the end surface) along the end surface of the tab laminate, wherein the second portion is located more inward than the first portion. , The conductive member, Serial cross-sectional area of the first section has a smaller cross section than the cross-sectional area of the second section.

  In the method of manufacturing an electrode assembly, the conductive member includes a first portion including a first cross section along an end surface of the tab laminate and a second portion including a second cross section along an end surface of the tab laminate. And the second portion is located on the inner side of the first portion, so that the first portion of the conductive member is heated. Here, the cross-sectional area of the first cross section is smaller than the cross-sectional area of the second cross section. Therefore, for example, the conductive member heats the first portion (that is, a part of the conductive member) as compared with a case where the cross-sectional area of the first cross section and the cross-sectional area of the second cross section have the same cross-sectional shape. The energy used can be reduced. Therefore, the energy required for welding the stacked tabs can be reduced.

  Further, the electrode assembly according to the embodiment is an electrode assembly having a plurality of electrodes each including a tab, the tab laminate having a plurality of tabs stacked, the tab laminate in the stacking direction of the tab laminate. A conductive member disposed on the tab laminate, and the tab laminate has a welded portion located inside from an end face of the tab laminate extending along a laminating direction of the tab laminate. The conductive member includes a first portion including a first section (for example, a plane parallel to the end face) along the end face of the tab laminate and a second section (for example, end face) along the end face of the tab laminate. (A plane parallel to the second part), the second part being located inside the first part, and the conductive member having a cross-sectional area of the first cross-section of the second cross-section. Has a cross-sectional shape smaller than the cross-sectional area of It can also be.

  The electrode assembly has a welded portion formed inside from the end face of the tab laminate, and the conductive member disposed on the tab laminate has a cross-sectional area of the first cross section of the second cross section. It has a cross-sectional shape smaller than the cross-sectional area. Therefore, for example, when a weld is formed by irradiating an energy beam as described above, the energy required for welding can be reduced.

3: Electrode assembly, 14b, 17b: Tab, 21, 25: Tab laminate, 21a, 21b, 21c, 25a, 25b, 25c: End face, 23, 27, 37, 47, 57: Protective plate (conductive member) , 27a, 27b, 37a, 37b, 47a, 47b, 57a, 57b... First portion, 27c, 37c, 47c, 57c... Second portion, C... Cutout portion, W. Plane, S2... Second plane.

Claims (8)

A method of manufacturing an electrode assembly having a plurality of electrodes each including a tab,
Have a stacked plurality of said tabs are, the tab laminate which projects from the body of the electrode assembly, a step of preparing a conductive member disposed on the tab laminate,
By irradiating an energy beam on the end face extending along the projecting direction of the tab laminate with extending along the laminating direction of the tab laminate, to form a welded portion inwardly from the end face of the tab laminate Process and
Including
In the preparing step, the conductive member is disposed in at least one position in the stacking direction of the tab stack, when viewed from the stack direction of the tab stack, with respect to the stack direction of the tab stack. In a plane orthogonal to the first plane, a first portion disposed in a first plane located inside from the end face of the tab laminate, and a second portion located inside the first plane. A second portion to be disposed;
The stacking direction of the tab laminate, wherein the conductive member has an area ratio of the first portion occupying the first plane smaller than an area ratio of the second portion occupying the second plane. A method for manufacturing an electrode assembly, having a cross-sectional shape orthogonal to the electrode assembly. In the step of preparing, the first portion has a notch, so that the ratio of the area of the first portion occupying the first plane to the second portion occupying the second plane is reduced. Is smaller than the area ratio of
A method for manufacturing an electrode assembly according to claim 1. The length of the notch in the stacking direction is the same as the length of the corresponding portion of the conductive member, and the surface of the tab laminate is exposed at the portion where the notch is located.
A method for manufacturing an electrode assembly according to claim 2. In the preparing step, the conductive member has a plate shape, and the thickness of at least a part of the first portion is smaller than the thickness of the second portion, so that the conductive member occupies the first plane. 4. The electrode assembly according to claim 1, wherein a ratio of an area of the first portion is smaller than a ratio of an area of the second portion to the second plane. 5. Production method. In the preparing step, a tip of the first portion of the conductive member is located at the end surface of the tab laminate when viewed from a laminating direction of the tab laminate, and is located on the tab laminate. The method for manufacturing an electrode assembly according to any one of claims 1 to 4 , wherein the electrode assembly is in contact with the electrode assembly. An electrode assembly having a plurality of electrodes each including a tab,
Have a stacked plurality of said tabs has a tab laminate which projects from the body of the electrode assembly,
A conductive member disposed on the tab laminate in the stacking direction of the tab laminate,
With
The tab laminate has a welded portion located inward from the end face extending along the projecting direction of the tab laminate with extending along the laminating direction of the tab laminate,
The conductive member, at least at any position in the lamination direction of the tab laminate, when viewed from the lamination direction of the tab laminate, in a plane perpendicular to the lamination direction of the tab laminate, the tab A first portion disposed in a first plane located inside the end face of the laminate, and a second portion disposed in a second plane located inside the first plane; Including
The stacking direction of the tab laminate, wherein the conductive member has an area ratio of the first portion occupying the first plane smaller than an area ratio of the second portion occupying the second plane. An electrode assembly having a cross-sectional shape that is orthogonal to. Since the first portion has the cutout portion, the ratio of the area of the first portion occupying the first plane is larger than the ratio of the area of the second portion occupying the second plane. 7. The electrode assembly according to claim 6 , wherein the electrode assembly is reduced. The length of the notch in the stacking direction is the same as the length of the corresponding portion of the conductive member, and the surface of the tab laminate is exposed at the portion where the notch is located.
The electrode assembly according to claim 7.

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