WO2017110247A1

WO2017110247A1 - Manufacturing method for electrode assembly, and electrode assembly

Info

Publication number: WO2017110247A1
Application number: PCT/JP2016/082110
Authority: WO
Inventors: 真也奥田; 雅巳冨岡; 雅人小笠原
Original assignee: 株式会社豊田自動織機
Priority date: 2015-12-21
Filing date: 2016-10-28
Publication date: 2017-06-29
Also published as: JP6834982B2; JPWO2017110247A1

Abstract

This manufacturing method for an electrode assembly which includes a plurality of electrodes each having a tab, comprises: a step for preparing a tab laminate having a plurality of laminated tabs; and a step for forming a welded portion on the inner side with respect to an end surface of the tab laminate extending in the lamination direction of the tab laminate, by irradiating the end surface with an energy beam. In the step for forming the welded portion, a direction obtained by projecting the energy-beam irradiation direction onto a plane, which is orthogonal to the lamination direction of the tab laminate and which intersects the end surface of the tab laminate, is inclined, in the plane, with respect to both the end surface of the tab laminate and the normal direction of the end surface of the tab laminate.

Description

Method for manufacturing electrode assembly and electrode assembly

One aspect of the present invention relates to a method for manufacturing an electrode assembly and an electrode assembly.

When manufacturing a lithium secondary battery, a method of welding a plurality of stacked current collecting tabs using a YAG laser or an electron beam is known (see Patent Document 1).

JP 2002-313309 A

In the above method, the YAG laser or the electron beam is irradiated in a direction orthogonal to the end face extending along the stacking direction of the current collecting tabs. For example, when irradiating a YAG laser or electron beam to the end face of the positive electrode current collector tab, if there is an object (for example, negative electrode current collector tab) facing the end face of the positive electrode current collector tab, the object shields the YAG laser or electron beam Resulting in. For this reason, the degree of freedom in designing the electrode assembly is low.

An object of one aspect of the present invention is to provide an electrode assembly manufacturing method and an electrode assembly with high design freedom.

An electrode assembly manufacturing method according to an aspect of the present invention is a method for manufacturing an electrode assembly having an electrode including a tab, the step of preparing a tab stack having the stacked tabs, and the tab stacking Forming a welded portion on the inner side from the end surface of the tab laminate by irradiating an energy beam to an end surface of the tab laminate extending along the stacking direction of the body, and forming the welded portion. In the step, the direction in which the irradiation direction of the energy beam is projected on a plane orthogonal to the stacking direction of the tab stack and intersecting the end surface of the tab stack is the end surface of the tab stack and the It inclines with respect to both the normal directions of the end surface of a tab laminated body.

In this electrode assembly manufacturing method, for example, even when an object facing the end face of the tab laminate is present, the irradiation direction of the energy beam can be adjusted so that the energy beam is not shielded by the object. Therefore, the degree of freedom in designing the electrode assembly is high.

In the step of preparing the tab laminate, a plurality of tab laminates are prepared, and in the step of forming the welded portion, an end surface of a first tab laminate of the plurality of tab laminates, and the plurality of tab laminates You may irradiate the said energy beam to each of the end surface of the 2nd tab laminated body of a tab laminated body. Further, the end surface of the first tab laminate and the end surface of the second tab laminate are arranged in a state where the end surface of the first tab laminate and the end surface of the second tab laminate are arranged to face each other. Each may be irradiated with the energy beam.

In this case, when irradiating the energy beam to one of the end surfaces of the first and second tab laminates, it becomes easy to arrange the energy beam irradiation device so that the other tab laminate does not shield the energy beam. .

The end face of the first tab laminate and the end face of the second tab laminate may be arranged along the transport direction of the plurality of tab laminates.

In this case, by conveying a plurality of tab laminates, the end surfaces of the first tab laminate and the end surfaces of the second tab laminate can be irradiated with an energy beam. Therefore, the productivity of the electrode assembly is improved.

The tab laminated body has a plurality of end faces arranged on opposite sides of the tab laminated body, and in the step of forming the welded portion, each of the plurality of end faces is irradiated with the energy beam. May be.

Thus, even when an unwelded portion is generated between tabs stacked on one end surface, an unwelded portion is hardly generated between tabs stacked on another end surface disposed on the opposite side.

The plurality of end faces may be arranged along the transport direction of the tab laminate.

In this case, an energy beam can be irradiated to a plurality of end faces by conveying the tab laminate. Therefore, the productivity of the electrode assembly is improved.

The electrode assembly includes a plurality of electrodes, each of the plurality of electrodes including a main body and the tab protruding from one end of the main body, and the electrode assembly includes a plurality of stacked main bodies. In the step of forming the welded portion, a shielding member disposed between the electrode body and the welded portion may shield the energy beam reflected by the end surface of the tab laminate. .

In this case, the energy beam reflected by the end face of the tab laminate is suppressed from damaging the electrode body.

The tab laminate is disposed between a conductive member and a current collector in the stacking direction of the tab laminate, and the thickness of the conductive member in the stacking direction of the tab laminate is the stacking direction of the tab laminate. It may be smaller than the thickness of the current collector.

In this case, since the thickness of the conductive member is relatively small, the difference between the heat capacity of the conductive member and the heat capacity of the tab can be reduced.

The maximum length of the welded portion in the direction orthogonal to the stacking direction of the tab laminate on the end surface of the tab laminate is between the stacking direction of the tab laminate and the direction orthogonal to the stacking direction of the tab laminate. When viewed from a direction orthogonal to both, the maximum length of a portion where the welded portion and the tab laminate overlap in the stacking direction of the tab laminate may be larger.

In this case, since the mechanical strength of the welded portion is increased, the welded portion is not easily broken even if stress is generated in the electrode assembly due to, for example, assembly work or external force. Moreover, a weld part can be enlarged in the direction orthogonal to the lamination direction of a tab laminated body in the end surface of a tab laminated body. As a result, since the thermal diffusibility of the welded portion is improved, the generation of sputtered particles due to the energy beam irradiation can be suppressed.

In the cross section of the tab laminate that includes the lamination direction of the tab laminate and is orthogonal to the end surface of the tab laminate, the maximum weld depth of the weld in the direction orthogonal to the lamination direction of the tab laminate is less than 2 mm. There may be.

In this case, the generation of sputtered particles due to the energy beam irradiation can be suppressed.

When viewed from the normal direction of the end face of the tab laminate, the weld may have an outer shape including a curve.

In this case, since the stress is difficult to concentrate on the curved portion of the outer shape of the welded portion, the welded portion is difficult to peel off.

An electrode assembly according to an aspect of the present invention is an electrode assembly including an electrode including a tab, the tab assembly including the tabs stacked, and the tab stack includes a stack of the tab stacks. A cross section of the tab laminate that has a welded portion located on the inner side from an end surface of the tab laminate that extends along a direction, and that is orthogonal to the lamination direction of the tab laminate and intersects the end surface of the tab laminate The boundary line of the welded portion extends in a direction inclined with respect to both the end surface of the tab laminate and the normal direction of the end surface of the tab laminate.

This electrode assembly includes a weld having a boundary extending in a desired direction. The direction of the boundary line is controlled by adjusting the irradiation direction of the energy beam when, for example, the weld is formed by the energy beam. At this time, for example, even when an object facing the end face of the tab laminate exists, the irradiation direction of the energy beam can be adjusted so that the energy beam is not shielded by the object. Therefore, the degree of freedom in designing the electrode assembly is high.

In this case, the welded portion spreads in the direction intersecting the stacking direction of the tab laminate on the end face of the tab laminate. As a result, when current flows in the stacking direction at the welded portion, the electrical resistance value between the stacked tabs can be reduced.

According to one aspect of the present invention, an electrode assembly manufacturing method and an electrode assembly with a high degree of design freedom can be provided.

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. FIG. 3 is a perspective view of the electrode assembly according to the first embodiment. FIG. 4 is a cross-sectional view of the electrode assembly taken along line IV-IV in FIG. FIG. 5 is a diagram illustrating one step in the method of manufacturing the electrode assembly according to the first embodiment. FIG. 6 is a diagram illustrating one step in the method of manufacturing the electrode assembly according to the first embodiment. FIG. 7 is a diagram illustrating one step in the method of manufacturing the electrode assembly according to the first embodiment. FIG. 8 is a diagram illustrating one step in the method of manufacturing the electrode assembly according to the first embodiment. FIG. 9 is a diagram illustrating one step in the method of manufacturing the electrode assembly according to the first embodiment. FIG. 10 is a diagram illustrating one step in the method of manufacturing the electrode assembly according to the second embodiment. FIG. 11 is a diagram illustrating one step of the method of manufacturing the electrode assembly according to the second embodiment. FIG. 12 is a diagram illustrating one step in the method of manufacturing the electrode assembly according to the third embodiment. FIG. 13 is a diagram illustrating one step in the method of manufacturing the electrode assembly according to the third embodiment. FIG. 14 is a view showing a part of an electrode assembly having a weld according to a modification. FIG. 15 is a diagram illustrating the evaluation results of the examples.

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 are used for the same or equivalent elements, and redundant descriptions are omitted. In the drawing, an XYZ orthogonal coordinate system is shown as necessary. The Z axis direction is, for example, the vertical direction, and the X axis direction and the Y direction are, for example, the 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.

1 and 2, the power storage device 1 includes a hollow case 2 having a substantially rectangular parallelepiped shape, for example, and an electrode assembly 3 accommodated in the case 2. The case 2 is made of a metal such as aluminum. The case 2 has a main body 2a that is open on one side and a lid 2b that closes the opening of the main body 2a. On the inner wall surface of the case 2, an insulating film (not shown) is provided. 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 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 spaced apart from each other on the lid 2 b of the case 2. The positive electrode terminal 5 is fixed to the case 2 via an insulating ring 7, and the negative electrode terminal 6 is fixed to the case 2 via an insulating ring 8.

The electrode assembly 3 is a stacked 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 electrodes 11 and the negative electrodes 12. For example, the positive electrode 11 is accommodated in the separator 13. In a state where the positive electrode 11 is accommodated in the separator 13, the plurality of positive electrodes 11 and the plurality of negative electrodes 12 are alternately stacked via the separators 13.

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 a 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 composite oxide, metallic lithium, and sulfur. The composite oxide includes, 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, an active material may be carried on the base end portion of the tab 14b on the main body 14a side.

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

The negative electrode 12 includes a metal foil 17 made of, for example, copper foil, and a negative electrode active material layer 18 formed on both surfaces of the metal foil 17. Similar to 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 by supporting a negative electrode active material on at least a central portion of the main body 17a on both surfaces of the main body 17a. 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 carbon such as graphite, highly oriented graphite, mesocarbon microbeads, hard carbon, and soft carbon, alkali metals such as lithium and sodium, metal compounds, SiOx (0.5 ≦ x ≦ 1.5 ) And the like, and boron-added carbon. Here, as an example, the tab 17b does not carry a 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 a current collector plate 19 (current collector). The current collector plate 19 is disposed between the tab 17 b and the negative electrode terminal 6. For example, the current collector plate 19 is formed in a rectangular flat plate shape from the same material as the metal foil 17 of the negative electrode 12. The plurality of stacked tabs 17b are disposed between the current collector plate 19 and a protective plate 27 (conductive member) thinner than the current collector plate 19 (see FIG. 3). For example, the protection plate 27 is formed in a rectangular flat plate shape from the same material as the metal foil 17 of the negative electrode 12.

The separator 13 accommodates the positive electrode 11. The separator 13 has a rectangular shape when viewed from the stacking 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), a woven fabric or a non-woven fabric made of polypropylene, polyethylene terephthalate (PET), methylcellulose, and the like.

FIG. 3 is a perspective view of the electrode assembly according to the first embodiment. FIG. 4 is a cross-sectional view of the electrode assembly taken along line IV-IV in FIG. The electrode assembly 3 shown in FIG. 3 includes a plurality of positive electrodes 11 and a plurality of negative electrodes 12 that are stacked on each other via a separator 13. 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 protruding from one end of the main body 17a in the X-axis direction. The

main bodies

14a and 17a are stacked on each other to form electrode main bodies 42 and 44, respectively. That is, the electrode assembly 3 includes an electrode main body 42 having a plurality of main bodies 14a stacked in the Z-axis direction and an electrode main body 44 having a plurality of main bodies 17a stacked in the Z-axis direction. The

tabs

14b and 17b are laminated with 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 laminated body 21 includes

end surfaces

21a, 21b, and 21c of the tab laminated body 21 extending along the lamination direction (Z-axis direction) of the tab laminated body 21. The end surfaces 21a and 21b are surfaces that sandwich the tab laminate 21, and the end surface 21c is a surface that connects the end surfaces 21a and 21b. That is, the end faces 21 a and 21 b 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 21 c is a surface that is inclined with respect to the XY plane so that the thickness of the tab laminated body 21 becomes smaller toward the tip of the tab laminated body 21.

The tab laminate 21 is disposed between the current collector plate 16 and the protective plate 23 in the Z-axis direction. That is, the tab laminate 21 is disposed on the current collector plate 16 in the Z-axis direction. The protection plate 23 is disposed on the tab laminate 21 in the Z-axis direction. The protective plate 23 is not in contact with the current collector plate 16, and the protective plate 23 and the current collector plate 16 are separated from each other with the tab laminate 21 sandwiched in the stacking direction. The tab laminate 21 is thicker than the protective plate 23, and the current collector plate 16 is thicker than the tab laminate 21. The thickness of the protective plate 23 is larger than the thickness of the tab 14 b and smaller than the thickness of the current collector plate 16. The electrode assembly 3 may not include the protection plate 23 and the current collector plate 16.

The length of the current collector plate 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 portion of the current collector plate 16 in the Y-axis direction coincides with the position of the end portion of the main body 14a in the Y-axis direction. The length of the protective 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 laminated body 21 has welded portions W located on the inner side from the end faces 21a and 21b of the tab laminated body 21, respectively. The maximum length W2 of the welded portion W in the direction (eg, the X-axis direction) orthogonal to the lamination direction of the tab laminate 21 on the end faces 21a, 21b of the tab laminate 21 is the lamination direction (eg, the Z-axis direction) of the tab laminate 21. ) And a direction (for example, the Y-axis direction) orthogonal to both the direction (for example, the X-axis direction) orthogonal to the stacking direction of the tab-layered structure 21, the stacking direction (for example, the Z-axis direction) of the tab stacked body 21 ) Is larger than the maximum length W1 of the portion where the welded portion W and the tab laminate 21 overlap (see FIG. 3). The welded portion W extends to the inside of the current collector plate 16 and the protective plate 23 adjacent to the end surfaces 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 protective plate 23 in the X-axis direction or shorter than the length of the protective plate 23 in the X-axis direction. Thereby, even if the tab 14b of the tab laminated body 21 is displaced in the X-axis direction (for example, when there is a displacement due to tolerance), the welded portion W can be stably formed. If 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. Further, when the length of the welded portion W in the X-axis direction is longer than the length of the protective plate 23 in the X-axis direction, the welded portion W protrudes outside the protective plate 23 in the X-axis direction. Even in those cases, the welded portion W can be formed.

As shown in FIG. 4, welding is performed in a cross section (for example, an XY cross section) of the tab laminated body 21 that is orthogonal to the laminating direction (Z-axis direction) of the tab laminated body 21 and intersects the end surfaces 21 a and 21 b of the tab laminated body 21. The boundary line Wa of the portion W extends in a direction inclined with respect to both the normal directions (for example, the Y-axis direction) of the end faces 21a and 21b of the tab laminated body 21 and the end faces 21a and 21b of the tab laminated body 21. The boundary line Wa may extend in the direction from the tip of the tab laminate 21 toward the electrode body 42. For example, the welded portion W has two boundary lines Wa, and the welded portion W depends on the shape of the molten pool formed around the energy beam B by irradiation with an energy beam B (see FIG. 6) described later. The distance between the two boundary lines Wa becomes narrower from the outer surface toward the inner side. The welding pool is formed so as to taper inward from the surface of the irradiation object of the energy beam B in the irradiation direction of the energy beam B.

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 that sandwich the tab laminate 25, and the end surface 25c is a surface that connects the end surfaces 25a and 25b. That is, the end faces 25a and 25b are disposed on the opposite sides of the tab laminate 25. The end surfaces 25a and 25b are surfaces along the XZ plane. The end surface 25 c is a surface that is inclined with respect to the XY plane so that the thickness of the tab laminated body 25 becomes smaller toward the tip of the tab laminated body 25.

The tab laminate 25 is disposed between the current collector plate 19 and the protective plate 27 in the Z-axis direction. That is, the tab laminate 25 is disposed on the current collector plate 19 in the Z-axis direction. The protection plate 27 is disposed on the tab laminate 25 in the Z-axis direction. The protective plate 27 is not in contact with the current collector plate 19, and the protective plate 27 and the current collector plate 19 are separated with the tab laminate 25 sandwiched in the stacking direction. The tab laminate 25 is thicker than the protective plate 27, and the current collector plate 19 is thicker than the tab laminate 25. The thickness of the protection plate 27 is larger than the thickness of the tab 17 b and smaller than the thickness of the current collector plate 19. The electrode assembly 3 may not include the protection plate 27 and the current collector plate 19.

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 faces 25a and 25b). In the Y-axis direction, the position of the outer end portion of the current collector plate 19 in the Y-axis direction matches the position of the end portion 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 laminated body 25 has welded portions W located on the inner sides from the end faces 25a and 25b of the tab laminated body 25, respectively. The end surface 25 b of the tab laminated body 25 faces the end surface 21 b of the tab laminated body 21. Therefore, the end faces 21a, 21b, 25a, and 25b of the tab laminates 21 and 25 are arranged along the Y-axis direction. The maximum length W2 of the welded portion W in the direction (eg, the X-axis direction) orthogonal to the lamination direction of the tab laminate 25 at the end faces 25a, 25b of the tab laminate 25 is the lamination direction (eg, the Z-axis direction) of the tab laminate 25 ) And a direction (for example, the Y-axis direction) orthogonal to both the direction (for example, the X-axis direction) orthogonal to the stacking direction of the tab-layered structure 25, the stacking direction (for example, the Z-axis direction) of the tab stacked body 25 ) Is larger than the maximum length W1 of the portion where the welded portion W and the tab laminate 25 overlap (see FIG. 3). The welded portion W extends to the inside of the current collector plate 19 and the protection plate 27 adjacent to the end surfaces 25a and 25b. In the end surfaces 25a and 25b, the length of the welded portion W in the X-axis direction is preferably substantially equal to the length of the protective plate 27 in the X-axis direction or shorter than the length of the protective plate 27 in the X-axis direction. Thereby, even if the tab 17b of the tab laminated body 25 is displaced in the X-axis direction (for example, when there is a displacement due to tolerance), the welded portion W can be stably formed. When the length of the welded portion W in the X-axis direction is substantially equal to the length of the protective plate 27 in the X-axis direction, the welded portion W may protrude outside the protective 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 protective plate 27 in the X-axis direction, the welded portion W protrudes outside the protective plate 27 in the X-axis direction. Even in those cases, the welded portion W can be formed.

As shown in FIG. 4, welding is performed in a cross section (for example, an XY cross section) of the tab laminated body 25 that is orthogonal to the lamination direction (Z-axis direction) of the tab laminated body 25 and intersects the end faces 25 a and 25 b of the tab laminated body 25. The boundary line Wa of the portion W extends in a direction inclined with respect to both the normal directions (for example, the Y-axis direction) of the end faces 25a and 25b of the tab laminated body 25 and the end faces 25a and 25b of the tab laminated body 25. The boundary line Wa may extend in the direction from the tip of the tab laminate 25 toward the electrode body 44. For example, the welded portion W has two boundary lines Wa, and the welded portion W depends on the shape of the molten pool formed around the energy beam B by irradiation with an energy beam B (see FIG. 6) described later. The distance between the two boundary lines Wa becomes narrower from the outer surface toward the inner side. The welding pool is formed so as to taper inward from the surface of the irradiation object of the energy beam B in the irradiation direction of the energy beam B.

In the electrode assembly 3 of the first embodiment, the boundary line Wa of the welded portion W is the

end surface

21a, 21b, 25a, 25b of the

tab laminate

21, 25 and the tab laminate in the XY cross section of the

tab laminate

21, 25. 21 and 25 extend in a direction inclined with respect to both normal directions of the end faces 21a, 21b, 25a and 25b. The extending direction of the boundary line Wa is controlled by, for example, the irradiation direction of the energy beam B applied to the end faces 21a, 21b, 25a, and 25b of the tab laminates 21 and 25 as described above.

The electrode assembly 3 of the first embodiment includes a welded portion W having a boundary line Wa extending in a desired direction. The extending direction of the boundary line Wa is controlled by adjusting the irradiation direction of the energy beam B when the welded portion W is formed by the energy beam B, for example. At this time, for example, even when there is an object facing the end faces 21a, 21b, 25a, 25b of the tab laminates 21, 25, the irradiation direction of the energy beam B is set so that the energy beam B is not shielded by the object. Can be adjusted. Therefore, the degree of freedom in designing the electrode assembly 3 is high.

Further, since the electrode assembly 3 is a stacked electrode assembly, the individual electrodes (the positive electrode 11 and the negative electrode 12) can move independently of each other as compared with the wound electrode assembly. Therefore, in the stacked electrode assembly, the main body 14a of the positive electrode 11 and the main body 17a of the negative electrode 12 may be displaced in at least one of the X-axis direction and the Y-axis direction, as compared with the wound electrode assembly. is there. Further, in addition to the displacement of the

main bodies

14a and 17a, the

tabs

14b and 17b may also be displaced in at least one of the X-axis direction and the Y-axis direction. Therefore, there is a possibility that the maximum value of the positional deviation of the

tabs

14b and 17b in the XY plane becomes large. Even in such a case, in the electrode assembly 3, since the welded portion W is formed on the end faces 21a, 21b, 25a, and 25b of the tab laminates 21 and 25, the welded portions W are not welded between the plurality of

tabs

14b and 17b. Part is hard to occur. In addition, the tab laminates 21 and 25 of the electrode assembly 3 of the battery having a large capacity become relatively thick, and the energy required for welding increases according to the thickness of the tab laminates 21 and 25. In that case, when welding by irradiation with the energy beam B is performed, the running cost of the welding apparatus can be reduced as compared with resistance welding using a welding electrode which is a consumable item.

When the electrode assembly 3 includes the

protection plates

23 and 27, the plurality of

tabs

14b and 17b are pressed via the

protection plates

23 and 27, so that it is difficult to generate a gap between the plurality of

tabs

14b and 17b. Therefore, it is difficult for voids to occur in the welded portion W when welding is performed.

In the cross section (for example, YZ cross section) of the tab laminated body 21 including the laminating direction of the tab laminated body 21 and orthogonal to the end faces 21a and 21b of the tab laminated body 21, the welded portion W in the direction orthogonal to the laminating direction of the tab laminated body 21 The maximum welding depth Wd may be less than 2 mm, may be 1.5 mm or less, may be 1.2 mm or less, may be greater than 0.1 mm, It may be 3 mm or more. Similarly, in the cross section (for example, YZ cross section) of the tab laminated body 25 that includes the laminating direction of the tab laminated body 25 and is orthogonal to the end faces 25a and 25b of the tab laminated body 25, welding in the direction orthogonal to the laminating direction of the tab laminated body 25 is performed. The maximum welding depth Wd of the part W may be less than 2 mm, 1.5 mm or less, 1.2 mm or less, or more than 0.1 mm. 0.3 mm or more. When the maximum welding depth Wd is less than 2 mm, for example, the generation of sputtered particles due to the irradiation with the energy beam B can be suppressed. In particular, when the maximum welding depth Wd is 1.2 mm or less, the generation of sputtered particles is significantly suppressed (see FIG. 15).

In the cross section (for example, XY cross section) of the tab laminated body 21 orthogonal to the lamination direction of the tab laminated body 21, the maximum area of the welded portion W is, for example, 4 to 40 mm ² . Similarly, in the cross section (for example, XY cross section) of the tab laminated body 25 orthogonal to the laminating direction of the tab laminated body 25, the maximum area of the welded portion W is, for example, 4 to 40 mm ² . When the maximum area of the welded portion W is 4 mm ² or more, the electric resistance value of the welded portion W can be sufficiently reduced.

As described above, in the electrode assembly 3, the maximum length W2 of the welded portion W in the direction (eg, the X-axis direction) orthogonal to the stacking direction of the tab stacked body 21 on the end faces 21a and 21b of the tab stacked body 21 is When viewed from a direction (for example, the Y-axis direction) orthogonal to both the stacking direction (for example, the Z-axis direction) of the stacked body 21 and the direction (for example, the X-axis direction) orthogonal to the stacking direction of the tab stacked body 21 It is larger than the maximum length W1 of the portion where the welded portion W and the tab laminate 21 overlap in the lamination direction of the laminate 21 (for example, the Z-axis direction) (see FIG. 3). Therefore, on the end faces 21 a and 21 b of the tab laminated body 21, the welded portion W spreads in a direction intersecting with the lamination direction of the tab laminated body 21. As a result, when current flows in the welding direction at the welded portion W, the electrical resistance value between the plurality of tabs 14b can be reduced. Similarly, the maximum length W2 of the welded portion W in the direction (for example, the X-axis direction) orthogonal to the stacking direction of the tab stacked body 25 on the end surfaces 25a and 25b of the tab stacked body 25 is the stacking direction of the tab stacked body 25 (for example, When viewed from a direction (for example, the Y-axis direction) orthogonal to both the Z-axis direction) and a direction (for example, the X-axis direction) orthogonal to the stack direction of the tab stack 25, the stack direction of the tab stack 25 (for example, It is larger than the maximum length W1 of the portion where the welded portion W and the tab laminate 25 overlap in the Z-axis direction). Therefore, on the end faces 25 a and 25 b of the tab laminated body 25, the welded portion W spreads in a direction intersecting with the lamination direction of the tab laminated body 25. As a result, when the current flows in the stacking direction in the welded portion W, the electrical resistance value between the plurality of tabs 17b can be reduced.

The tab laminated body 21 is disposed between the protective plate 23 and the current collector plate 16 in the lamination direction of the tab laminated body 21, and the thickness of the protective plate 23 in the lamination direction of the tab laminated body 21 is the lamination of the tab laminated body 21. It may be smaller than the thickness of the current collector plate 16 in the direction. In this case, since the thickness of the protective plate 23 is relatively small, the difference between the heat capacity of the protective plate 23 and the heat capacity of the tab 14b can be reduced. Therefore, the quality of the welding part W in the contact location of the protection plate 23 and the tab 14b improves. The thickness of the protective plate 23 in the stacking direction of the tab laminate 21 may be larger than the thickness of the tab 14 b in the stacking direction of the tab laminate 21.

The thickness of the protective plate 23 may be 0.1 to 0.5 mm or 0.1 to 0.2 mm. If the thickness of the protective plate 23 is less than 0.1 mm, the force with which the protective plate 23 presses the tab 14b becomes small, and thus the tab 14b tends to move during welding. If the thickness of the protective plate 23 is more than 0.5 mm, the energy for melting the protective plate 23 during welding tends to increase. When the output of the energy beam B is increased to increase the energy, sputtered particles due to the irradiation of the energy beam B are likely to be generated. The thickness of the tab 14b is, for example, 5 to 30 μm. The thickness of the tab laminate 21 may be, for example, 0.3 to 2.4 mm, or 0.6 to 1.0 mm.

Similarly, the tab laminated body 25 is disposed between the protective plate 27 and the current collector plate 19 in the laminating direction of the tab laminated body 25, and the thickness of the protective plate 27 in the laminating direction of the tab laminated body 25 is determined by the tab laminated body. It may be smaller than the thickness of the current collector plate 19 in the 25 stacking direction. In this case, since the thickness of the protection plate 27 is relatively small, the difference between the heat capacity of the protection plate 27 and the heat capacity of the tab 17b can be reduced. Therefore, the quality of the welding part W in the contact location of the protection board 27 and the tab 17b improves. The thickness of the protection plate 27 in the stacking direction of the tab laminate 25 may be larger than the thickness of the tab 17b in the stacking direction of the tab stack 25.

The thickness of the protective plate 27 may be, for example, 0.1 to 0.5 mm or 0.1 to 0.2 mm. When the thickness of the protection plate 27 is less than 0.1 mm, the force with which the protection plate 27 presses the tab 17b is reduced, and thus the tab 17b tends to move during welding. If the thickness of the protective plate 27 is more than 0.5 mm, the energy for melting the protective plate 27 during welding tends to increase. When the output of the energy beam B is increased to increase the energy, sputtered particles due to the irradiation of the energy beam B are likely to be generated. The thickness of the tab 17b is, for example, 5 to 30 μm. The thickness of the tab laminate 25 may be, for example, 0.3 to 2.4 mm, or 0.6 to 1.0 mm.

FIG. 5 to FIG. 9 are views showing one process of the manufacturing method of the electrode assembly according to the first embodiment. The electrode assembly 3 shown in FIG. 3 is manufactured, for example, by the following method.

(Preparation process of tab laminate)
First, as shown in FIG. 5, a plurality of tab laminates 21 and 25 are prepared. 5A is a diagram showing the tab laminates 21 and 25 viewed from the Z-axis direction, and FIG. 5B is a diagram showing the tab laminate 25 viewed from the Y-axis direction. For example, first, tab laminates 21 and 25 are formed by laminating

tabs

14b and 17b on

current collector plates

16 and 19, respectively. Thereafter, the

protection plates

23 and 27 are placed on the tab laminates 21 and 25, respectively. The tab laminates 21 and 25 are pressed through the

protective plates

23 and 27 by a jig, for example, but may not be pressed.

(Formation process of welded part)
Next, as shown in FIG. 6, the energy beam B is applied to the end face 25 a of the tab laminate 25 (first tab laminate). 6A is a diagram showing the tab laminates 21 and 25 viewed from the Z-axis direction, and FIG. 6B is a diagram showing the tab laminate 25 viewed from the Y-axis direction. The energy beam B is irradiated from the irradiation device 30 toward the end surface 25a of the tab laminate 25. The irradiation device 30 is a scanner head including a lens and a galvanometer mirror, for example. A beam generator is connected to the scanner head via a fiber. The irradiating device 30 may be composed of a diffractive optical system such as a refractive type such as a prism or a diffractive optical element (DOE).

The direction J in which the irradiation direction of the energy beam B is projected onto a plane (for example, XY plane) orthogonal to the stacking direction (Z-axis direction) of the tab stack 25 and intersecting the end surface 25a of the tab stack 25 is the plane (for example, (XY plane) is inclined with respect to both the normal direction (for example, the Y-axis direction) of the end surface 25a of the tab stacked body 25 and the end surface 25a of the tab stacked body 25. The energy beam B may be applied in a direction from the tip of the tab laminate 25 toward the electrode main body 44. In this case, it is possible to suppress the energy beam B from being shielded by the electrode body 44. The irradiation direction of the energy beam B may be a direction in a plane (for example, XY plane) orthogonal to the stacking direction (Z-axis direction) of the tab stack 25 and intersecting the end surface 25a of the tab stack 25, The direction may intersect with the plane (for example, the XY plane). In the XY plane, the smaller angle θ among the angles formed by the end face 25a of the tab laminate 25 and the direction J may be 5 to 85 °, 10 to 80 °, or 45 to 75. It may be °. The energy beam B is a high energy beam that can be welded. The energy beam B is, for example, a laser beam or an electron beam. The irradiation with the energy beam B is performed in an atmosphere of an inert gas G supplied from the nozzle 32.

The energy beam B is irradiated to the end surface 25a of the tab laminated body 25 in a state where the tab laminated body 25 is pressed in the Z-axis direction via the current collector plate 19 and the protective plate 27 by a jig, for example.

The work including the

current collecting plates

16 and 19, the tab laminates 21 and 25, and the

protection plates

23 and 27 is placed on a transfer stage 40 such as a belt conveyor, and is transferred in the Y-axis direction to the irradiation position of the energy beam B. Is done.

The energy beam B is scanned along the direction (X-axis direction) intersecting the Z-axis direction on the end surface 25a of the tab laminate 25. In the first embodiment, scanning is performed along the X-axis direction while displacing the energy beam B in the Z-axis direction. For example, the energy beam B is scanned along the X-axis direction while being reciprocally displaced (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 H1 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 face 25a of the tab laminate 25 in the Z-axis direction. For example, the energy beam B is scanned while moving the center point along the X-axis direction on the end face 25a of the tab laminate 25 and rotating the irradiation spot of the energy beam B around the center point on the XZ plane. It is preferable that the diameter of rotation is larger than the thickness of the tab laminate 25 because the end face 25a, the current collector plate 19 and the protective plate 27 of the tab laminate 25 can be welded as a whole.

By irradiating the energy beam B as described above, the welded portion W is formed on the inner side from the end face 25a of the tab laminate 25 as shown in FIG. 7A is a diagram showing the tab laminates 21 and 25 viewed from the Z-axis direction, and FIG. 7B is a diagram showing the tab laminate 25 viewed from the Y-axis direction. In the XY cross section of the tab laminated body 25, the boundary line Wa of the welded portion W extends in a direction inclined with respect to both the end surface 25 a of the tab laminated body 25 and the normal direction of the end surface 25 a of the tab laminated body 25. The maximum length W2 of the welded portion W in the end surface 25a of the tab laminated body 25 in a direction orthogonal to the lamination direction of the tab laminated body 25 (for example, the X-axis direction) is equal to the lamination direction of the tab laminated body 25 (for example, the Z-axis direction). When viewed from a direction (for example, the Y-axis direction) orthogonal to both the direction (for example, the X-axis direction) orthogonal to the stacking direction of the tab-layered body 25, the tab layered body 25 in the stacking direction (for example, the Z-axis direction) It is larger than the maximum length W1 of the portion where the welded portion W and the tab laminate 25 overlap. The maximum length W1 is smaller than the maximum length of the welded portion W in the Z-axis direction.

Subsequently, as shown in FIG. 8, the end face 21b of the tab laminated body 21 (second tab laminated body) is similarly irradiated with the energy beam B. That is, the direction J in which the irradiation direction of the energy beam B is projected onto a plane (for example, an XY plane) orthogonal to the stacking direction (Z-axis direction) of the tab stack 21 and intersecting the end surface 21b of the tab stack 21 is the plane In (for example, XY plane), it inclines with respect to both the normal line direction (for example, Y-axis direction) of the end surface 21b of the tab laminated body 21, and the end surface 21b of the tab laminated body 21. Of the angles formed by the end face 21b of the tab laminate 21 and the direction J in the XY plane, the smaller angle θ may be 5 to 85 °, 10 to 80 °, or 45 to 75. It may be °. As a result, as shown in FIG. 9, the welded portion W is also formed from the end surface 21 b of the tab laminated body 21 to the inside.

The energy beam B is applied to the end face 21b in a state where the end face 25b of the tab laminated body 25 and the end face 21b of the tab laminated body 21 are arranged to face each other. When the distance in the Y-axis direction between the tips of the tab laminates 21 and 25 is L1, and the distance in the X-axis direction between the irradiation position of the energy beam B on the end face 21b and the tip of the tab laminate 25 is L2, It may be tan θ ≦ L1 / L2. In this case, it is possible to suppress the energy beam B applied to the end surface 21b from being shielded by the tab laminated body 25 disposed to face the end surface 21b. When the protruding direction of the tab laminates 21 and 25 is along the X-axis direction, θ ≦ 25 ° is preferable.

When irradiating the energy beam B, the shielding member 50 disposed between the electrode bodies 42 and 44 and the welded portion W may shield the energy beam B reflected by the end surface 21 b of the tab laminate 21. . The shielding member 50 may be a reflector that reflects the energy beam B reflected by the end surface 21b, or may be an absorber that absorbs the energy beam B reflected by the end surface 21b. When the end face 21b of the tab laminate 21 is irradiated with the energy beam B in a state where the shielding member 50 is disposed, the energy beam B reflected by the end face 21b is suppressed from damaging the electrode bodies 42 and 44.

Subsequently, similarly to the end face 21b of the tab laminated body 21, the welded portion W is formed on the inner side from the end face 25b of the tab laminated body 25 by irradiating the end surface 25b of the tab laminated body 25 with the energy beam B (FIG. 4). reference). The energy beam B is applied to the end face 25b in a state where the end face 25b of the tab laminated body 25 and the end face 21b of the tab laminated body 21 are arranged to face each other. When the distance in the Y-axis direction between the tips of the tab laminates 21 and 25 is L1, and the distance in the X-axis direction between the irradiation position of the energy beam B on the end face 25b and the tip of the tab laminate 21 is L2, It may be tan θ ≦ L1 / L2. In this case, it is possible to suppress the energy beam B applied to the end face 25b from being shielded by the tab laminate 21 arranged to face the end face 25b. Further, when the end face 25b is irradiated with the energy beam B, the energy beam B reflected by the end face 25b of the tab laminate 25 is provided by arranging the shielding member 50 between the electrode bodies 42 and 44 and the welded portion W. May be shielded. In this case, the energy beam B reflected by the end face 25b of the tab laminate 25 is suppressed from damaging the electrode bodies 42 and 44. When the energy beam B is infrared laser light, the reflectance of the energy beam B reflected by the tab 17b containing copper is higher than the reflectance of the energy beam B reflected by the tab 14b containing aluminum. In such a case, the shielding member 50 is particularly effective. Then, similarly to the end surface 25b of the tab laminated body 25, the end surface 21a of the tab laminated body 21 is irradiated with the energy beam B, thereby forming a welded portion W from the end surface 21a of the tab laminated body 21 (see FIG. 4). ). The shielding member 50 may be used when the end surfaces 25a and 21a are irradiated with the energy beam B. In this case, the energy beam B reflected by the end faces 25a and 21a is prevented from damaging the electrode bodies 42 and 44.

During irradiation of the energy beam B, the work including the tab laminates 21 and 25 is transported in the Y-axis direction by the transport stage 40 to the irradiation position of the energy beam B. The end surfaces 21a and 25b of the tab laminates 21 and 25 are irradiated with the energy beam B using the first irradiation device 30, and the end surfaces 21b and 25a of the tab laminates 21 and 25 are used using the second irradiation device 30. May be irradiated with the energy beam B. Further, the end surfaces 25a, 21b, 25b, and 21a may be sequentially irradiated with the energy beam B by moving one irradiation device 30 with a driving device such as a motor to change the irradiation direction of the energy beam B.

The electrode assembly 3 is manufactured through the above steps. 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 method for manufacturing the electrode assembly according to the first embodiment, for example, even when an object facing the end faces 21a, 21b, 25a, and 25b of the tab laminates 21 and 25 exists, the energy beam The irradiation direction of the energy beam B can be adjusted so that B is not shielded by the object. Therefore, for example, since the electrode assembly 3 can be designed so that the welded portion W is positioned on the end faces 21b and 25b of the tab laminates 21 and 25, the design flexibility of the electrode assembly 3 is high.

As shown in FIG. 8, when the end surface 21b is irradiated with the energy beam B in a state where the end surface 25b of the tab stacked body 25 and the end surface 21b of the tab stacked body 21 are opposed to each other, the tab stacked body 25 It becomes easy to arrange the irradiation device 30 of the energy beam B so as not to shield the beam B. On the other hand, when the energy beam is irradiated in the Y-axis direction, since the distance between the end surface 25b of the tab laminate 25 and the end surface 21b of the tab laminate 21 is narrow, the energy beam irradiation device which is a relatively large device is used as the end surface. It is difficult to arrange between 25b and the end face 21b. Similarly, when the energy beam B is applied to the end face 25b, the energy beam B irradiation device 30 can be easily disposed so that the tab laminate 21 does not shield the energy beam B.

In the present embodiment, as shown in FIG. 8, the end surfaces 21a, 21b, 25a, 25b of the tab laminates 21, 25 are arranged along the transport direction (Y-axis direction) of the tab laminates 21, 25. The In this case, the end surfaces 21a, 21b, 25a, and 25b can be irradiated with the energy beam B by conveying the tab laminates 21 and 25 in the Y-axis direction. Therefore, the productivity of the electrode assembly 3 is improved. For example, first, the energy beams B can be sequentially irradiated onto the end faces 25a and 21b. Subsequently, the energy beam B can be sequentially irradiated onto the end faces 25b and 21a.

When the welded portion W is formed by irradiating each of the end faces 25a and 25b of the tab laminate 25 with the energy beam B, the two end faces 25a and 25b arranged on the opposite sides of each other are not between the plurality of tabs 17b. Situations where welds occur are unlikely to occur. In particular, when the welded portion W can be formed on the two end faces 25a and 25b arranged on the opposite sides, resistance to stress is strong even if stress that causes separation between the tabs 17b is applied. Therefore, it is not necessary to form the welded portion W on the end surface 25c of the tab laminate 25. This eliminates the need for a step of cutting the tip including the end face 25c of the tab laminate 25 along the YZ plane, so that the productivity of the electrode assembly 3 is improved. Alternatively, if the end face 25c is welded without cutting the tip including the end face 25c, welding is performed on the tab laminate 25 having a different lamination thickness for each location. In that case, it is necessary to change the energy required for welding from place to place, but this is not necessary unless the end face 25c is welded. Similarly, the tab laminate 21 is unlikely to have a situation in which unwelded portions are generated between the tabs 14b on the two

end surfaces

21a and 21b arranged on the opposite sides. Therefore, it is not necessary to form the welded portion W on the end surface 21c of the tab laminate 21.

The maximum length W2 of the welded portion W in the direction orthogonal to the laminating direction of the tab laminated body 21 on the end surfaces 21a and 21b of the tab laminated body 21 is determined by the laminating direction (for example, the Z-axis direction) of the tab laminated body 21 and the tab laminated body 21. The welded portion W in the stacking direction (for example, the Z-axis direction) of the tab laminate 21 when viewed from the direction (for example, the Y-axis direction) orthogonal to both the direction orthogonal to the stacking direction (for example, the X-axis direction). It is larger than the maximum length W1 of the portion where the tab laminate 21 overlaps. Similarly, the maximum length W2 of the welded portion W in the direction orthogonal to the stacking direction of the tab stacked body 25 on the end faces 25a and 25b of the tab stacked body 25 is equal to the stacking direction of the tab stacked body 25 (for example, the Z-axis direction). Welding in the stacking direction (for example, the Z-axis direction) of the tab stack 25 when viewed from the direction (for example, the Y-axis direction) orthogonal to both the direction (for example, the X-axis direction) orthogonal to the stacking direction of the stacked body 25. It is larger than the maximum length W1 of the portion where the portion W and the tab laminate 25 overlap. In such a case, since the mechanical strength of the welded portion W is increased, the welded portion W is not easily destroyed even if stress is generated in the electrode assembly 3 due to, for example, assembly work or external force. In addition, the welded portion W can be enlarged in the direction orthogonal to the stacking direction of the tab stacked body 21 on the end surfaces 21 a and 21 b of the tab stacked body 21. Similarly, the welded portion W can be enlarged in the direction orthogonal to the stacking direction of the tab laminate 25 on the end faces 25a and 25b of the tab laminate 25. As a result, since the thermal diffusibility of the weld W is improved, the generation of sputtered particles due to the irradiation of the energy beam B can be suppressed.

FIG. 10 to FIG. 11 are views showing one process of the manufacturing method of the electrode assembly according to the second embodiment. FIGS. 10A and 11A are views showing the tab laminates 21 and 25 viewed from the X-axis direction, and FIGS. 10B and 11B are tab stacks viewed from the Z-axis direction. It is a figure which shows the

bodies

21 and 25. FIG. In 2nd Embodiment, the electrode assembly 3 can be manufactured similarly to 1st Embodiment except the welding part W being formed in the end surfaces 21c and 25c of the tab laminated

bodies

21 and 25, respectively.

The end surface 25c of the tab laminated body 25 is located at the tip of the tab laminated body 25 and is a surface along the YZ plane. The end face 25c may be formed by cutting the tip end of the tab laminate 25, or may be formed by laminating the tab 17b using tabs 17b having different lengths.

As shown in FIG. 10, the irradiation direction of the energy beam B is projected onto a plane (for example, an XY plane) orthogonal to the stacking direction (Z-axis direction) of the tab stack 25 and intersecting the end surface 25c of the tab stack 25. The direction J is inclined with respect to both the end surface 25c of the tab stacked body 25 and the normal direction (for example, the X-axis direction) of the end surface 25c of the tab stacked body 25 in the plane (for example, the XY plane). The energy beam B is scanned along the Y-axis direction while being displaced (wobbling) in the Z-axis direction on the end face 25c. The irradiation spot of the energy beam B moves from the position P4 on the axis H1 along the Y-axis direction to the position P5 on the end face 25c. For example, the positions P4 and P5 are located at the center of the end face 25c in the Z-axis direction. For example, the energy beam B is scanned while moving the center point along the Y-axis direction on the end face 25c and rotating the irradiation spot of the energy beam B around the center point on the YZ plane.

As shown in FIG. 11, the welded portion W is formed on the inner side from the end face 25 c of the tab laminated body 25 by the irradiation of the energy beam B. The boundary line Wa of the welded portion W extends in a direction inclined with respect to both the normal direction (for example, the X-axis direction) of the end surface 25c and the end surface 25c in the XY cross section of the tab laminate 25.

Similarly, by irradiating the end surface 21c of the tab laminated body 21 with the energy beam B, the welded portion W is also formed on the end surface 21c of the tab laminated body 21. The boundary line Wa of the welded portion W extends in a direction inclined with respect to both the end surface 21c and the normal direction (for example, the X-axis direction) of the end surface 21c in the XY cross section of the tab laminate 21.

In the second embodiment, the same effects as those in the first embodiment can be obtained. Moreover, in 2nd Embodiment, since the welding part W is formed also in the end surface 25c in addition to the end surfaces 25a and 25b of the tab laminated body 25, the electrical resistance value between the tabs 17b can be reduced. Similarly, the electrical resistance value between the tabs 14b can also be reduced by forming the welded portion W on the end face 21c. The welded portion W may not be formed on the end surfaces 21a, 21b, 25a, and 25b of the tab laminates 21 and 25, and the welded portion W may be formed only on the end surfaces 21c and 25c of the tab laminates 21 and 25.

FIG. 12 to FIG. 13 are views showing one process of the manufacturing method of the electrode assembly according to the third embodiment. 12A and 13A are views showing the tab laminate 25 viewed from the X-axis direction, and FIGS. 12B and 13B are tab laminates 25 viewed from the Z-axis direction. FIG. In the third embodiment, the electrode assembly 3 can be manufactured in the same manner as in the first embodiment, except that the wound electrode assembly 3 is manufactured instead of the stacked electrode assembly 3.

The wound electrode assembly 3 includes tab laminates 21 and 25, similar to the stacked electrode assembly 3. The tab laminates 21 and 25 are disposed on opposite sides in the X-axis direction. In the tab laminate 25, the tab 17b is wound around the axis in the X-axis direction and then compressed in the Z-axis direction. Therefore, the tab laminate 25 includes tabs 17b that are laminated in the Z-axis direction. Specifically, a plurality of portions in the tab 17b are stacked in the Z-axis direction. The welded portion W connects the stacked tabs 17b. Specifically, a plurality of portions in the tab 17b are connected by the welded portion W. In the wound electrode assembly 3, the tab laminate 25 does not include the end surfaces 25a and 25b, but includes only the end surface 25c located at the tip. Similarly, the tab laminate 21 does not include the end surfaces 21a and 21b, but includes only the end surface 21c located at the tip.

As shown in FIG. 12, the energy beam B is applied to the end face 25c of the tab laminate 25 as in the third embodiment.

As shown in FIG. 13, the welded portion W is formed on the inner side from the end surface 25 c of the tab laminated body 25 by the irradiation of the energy beam B. The boundary line Wa of the welded portion W extends in a direction inclined with respect to both the normal direction (for example, the X-axis direction) of the end surface 25c and the end surface 25c in the XY cross section of the tab laminate 25.

In the third embodiment, the same operational effects as in the second embodiment can be obtained.

FIG. 14 is a view showing a part of an electrode assembly having a weld according to a modification. FIG. 14A is a diagram illustrating the tab laminate 25 as viewed from the Y-axis direction, which has the welded portion W according to the first modification. FIG. 14B is a view showing the tab laminate 25 as viewed from the Y-axis direction, having the welded portion W according to the second modification. In the first and second modified examples, when viewed from the normal direction of the end face 25a of the tab laminate 25, the welded portion W has an outer shape including a curve. For this reason, the stress is difficult to concentrate on the curved portion of the outer shape of the welded portion W, so that the welded portion W is difficult to peel off. The welded portion W may have an outer shape surrounded by a curve, or may have an outer shape surrounded by a curve and a straight line. The outer shape of the welded portion W does not include a corner portion (a portion where straight lines intersect) where stress is likely to concentrate.

The outer shape of the welded portion W according to the first modification includes, for example, a part of an ellipse. As shown in FIG. 14A, the maximum length W2 of the welded portion W in the direction (X-axis direction) orthogonal to the laminating direction of the tab laminated body 25 on the end surface 25a of the tab laminated body 25 is the tab laminated body 25. Direction of the tab laminate 25 when viewed from a direction (Y-axis direction) perpendicular to both the direction of lamination (Z-axis direction) and the direction orthogonal to the direction of lamination of the tab laminate 25 (X-axis direction). It is larger than the maximum length W1 of the portion where the welded portion W and the tab laminate 25 overlap in the (Z-axis direction).

The outer shape of the welded portion W according to the second modification includes, for example, a part of a circle. As shown in FIG. 14B, the maximum length W2 of the welded portion W in the direction (X-axis direction) orthogonal to the stacking direction of the tab stacked body 25 on the end surface 25a of the tab stacked body 25 is the tab stacked body 25. Direction of the tab laminate 25 when viewed from a direction (Y-axis direction) perpendicular to both the direction of lamination (Z-axis direction) and the direction orthogonal to the direction of lamination of the tab laminate 25 (X-axis direction). It is larger than the maximum length W1 of the portion where the welded portion W and the tab laminate 25 overlap in the (Z-axis direction). The maximum length W2 may be equal to or less than the maximum length W1.

In at least one of the end face 25b of the tab laminate 25 and the end faces 21a and 21b of the tab laminate 21, the welded portion W has the same shape as the welded portion W according to the first modified example or the second modified example. May be.

The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments. The components of the above embodiments can be arbitrarily combined.

Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to the following examples.

Example 1
The welded portion W was formed so that the maximum weld depth Wd of the welded portion W was 0.1 mm.

(Example 2)
A weld W was formed in the same manner as in Example 1 except that the maximum weld depth Wd of the weld W was 0.3 mm.

(Example 3)
A weld W was formed in the same manner as in Example 1 except that the maximum weld depth Wd of the weld W was 1.2 mm. The power of the laser used for forming the weld W was 1500 W, and the scanning speed was 24.9 mm / sec.

Example 4
A weld W was formed in the same manner as in Example 1 except that the maximum weld depth Wd of the weld W was 1.5 mm. The output of the laser used for forming the weld W was 1500 W, and the scanning speed was 8.3 mm / sec.

(Example 5)
A welded portion W was formed in the same manner as in Example 1 except that the maximum weld depth Wd of the welded portion W was 2 mm.

(Evaluation results)
The evaluation results of Examples 1 to 5 are shown in FIG. The state of irradiating the end surface of the tab laminate with a laser beam was imaged, and the number of sputtered particles resulting from the laser beam irradiation was counted from the obtained image. In Examples 4 to 5, the number of sputtered particles was remarkably increased compared to Examples 1 to 3. Moreover, the electrical resistance value of the weld W was measured. A in the table shown in FIG. 15 indicates that good results were obtained, and B indicates that results that were not better than A were obtained. In Examples 2 to 4, good results were obtained as compared to Examples 1 and 5. According to the evaluation result of FIG. 15, when the maximum welding depth Wd of the welded portion W is 0.3 to 1.5 mm, the number of sputtered particles is reduced. Further, when the maximum welding depth Wd is 0.3 to 1.2 mm, the number of sputtered particles is remarkably reduced, and the electric resistance value of the welded portion W is a good value.

DESCRIPTION OF SYMBOLS 3 ... Electrode assembly, 11 ... Positive electrode (electrode), 12 ... Negative electrode (electrode), 14a, 17a ... Main body, 14b, 17b ... Tab, 21, 25 ... Tab laminated body, 21a, 21b, 21c, 25a, 25b, 25c ... end face, 23, 27 ... protective plate (conductive member), 42, 44 ... electrode body, 50 ... shielding member, B ... energy beam, W ... weld, Wa ... boundary line.

Claims

A method for manufacturing an electrode assembly having an electrode including a tab, comprising:
Preparing a tab laminate having the tabs laminated;
Irradiating the end surface of the tab laminate extending along the stacking direction of the tab laminate with an energy beam to form a welded portion from the end surface of the tab laminate to the inside;
Including
In the step of forming the welded portion, the direction in which the irradiation direction of the energy beam is projected on a plane orthogonal to the stacking direction of the tab stack and intersecting the end surface of the tab stack is the tab stack A manufacturing method of an electrode assembly, which is inclined with respect to both a normal direction of an end face of the body and an end face of the tab laminate.
In the step of preparing the tab laminate, a plurality of tab laminates are prepared,
In the step of forming the welded portion, the end surface of the first tab laminated body of the plurality of tab laminated bodies and the end surface of the second tab laminated body of the plurality of tab laminated bodies are respectively described above. The method for manufacturing an electrode assembly according to claim 1, wherein the energy beam is irradiated.
With the end face of the first tab laminate and the end face of the second tab laminate facing each other, the end face of the first tab laminate and the end face of the second tab laminate, respectively. The method for manufacturing an electrode assembly according to claim 2, wherein the energy beam is irradiated.
4. The electrode assembly manufacturing method according to claim 2, wherein an end face of the first tab laminate and an end face of the second tab laminate are arranged along a conveying direction of the plurality of tab laminates. Method.
The tab laminate has a plurality of end faces arranged on opposite sides of the tab laminate,
The method of manufacturing an electrode assembly according to any one of claims 1 to 4, wherein, in the step of forming the weld portion, each of the plurality of end faces is irradiated with the energy beam.
The method for manufacturing an electrode assembly according to claim 5, wherein the plurality of end faces are arranged along a conveying direction of the tab laminate.
The electrode assembly comprises a plurality of electrodes;
Each of the plurality of electrodes includes a main body and the tab protruding from one end of the main body,
The electrode assembly further comprises an electrode body having a plurality of stacked bodies,
In the step of forming the welded portion, a shielding member disposed between the electrode body and the welded portion shields the energy beam reflected by the end surface of the tab laminate. The manufacturing method of the electrode assembly as described in any one.
The tab laminate is disposed between the conductive member and the current collector in the stacking direction of the tab laminate,
The electrode assembly according to any one of claims 1 to 7, wherein the thickness of the conductive member in the stacking direction of the tab laminate is smaller than the thickness of the current collector in the stacking direction of the tab laminate. Production method.
The maximum length of the welded portion in the direction orthogonal to the stacking direction of the tab laminate on the end surface of the tab laminate is between the stacking direction of the tab laminate and the direction orthogonal to the stacking direction of the tab laminate. 9. When viewed from a direction orthogonal to both, the maximum length of a portion where the welded portion and the tab laminate overlap in the stacking direction of the tab laminate is greater than one. Of manufacturing the electrode assembly.
In the cross section of the tab laminate that includes the lamination direction of the tab laminate and is orthogonal to the end surface of the tab laminate, the maximum weld depth of the weld in the direction orthogonal to the lamination direction of the tab laminate is less than 2 mm. The method for manufacturing an electrode assembly according to any one of claims 1 to 9.
The method for manufacturing an electrode assembly according to any one of claims 1 to 10, wherein the welded portion has an outer shape including a curve when viewed from a normal direction of an end face of the tab laminate.
An electrode assembly comprising a plurality of electrodes each including a tab,
A tab laminate having a plurality of stacked tabs,
The tab laminate has a weld portion located on an inner side from an end surface of the tab laminate extending in the stacking direction of the tab laminate;
In the cross section of the tab laminate that is orthogonal to the stacking direction of the tab laminate and intersects the end face of the tab laminate, the boundary line of the welded portion is the end face of the tab laminate and the end face of the tab laminate. An electrode assembly extending in a direction inclined with respect to both normal directions.
The tab laminate is disposed between the conductive member and the current collector in the stacking direction of the tab laminate,
The electrode assembly according to claim 12, wherein a thickness of the conductive member in the stacking direction of the tab laminate is smaller than a thickness of the current collector in the stacking direction of the tab laminate.
The maximum length of the welded portion in the direction orthogonal to the stacking direction of the tab laminate on the end surface of the tab laminate is between the stacking direction of the tab laminate and the direction orthogonal to the stacking direction of the tab laminate. The electrode assembly according to claim 12 or 13, wherein the electrode assembly is larger than a maximum length of a portion where the welded portion and the tab laminate overlap in the stacking direction of the tab laminate when viewed from a direction orthogonal to both.
In the cross section of the tab laminate that includes the lamination direction of the tab laminate and is orthogonal to the end surface of the tab laminate, the maximum weld depth of the weld in the direction orthogonal to the lamination direction of the tab laminate is less than 2 mm. The electrode assembly according to any one of claims 12 to 14, wherein:
The electrode assembly according to any one of claims 12 to 15, wherein the welded portion has an outer shape including a curve when viewed from a normal direction of an end face of the tab laminate.