JP2020013733A - Power storage device and manufacturing method thereof - Google Patents

Abstract

To provide a power storage device that can suppress poor connection between uncoated parts and a manufacturing method thereof.SOLUTION: A secondary battery includes: an electrode assembly 12 in which a plurality of positive electrodes 21 and negative electrodes 22 having tabs 26 which are uncoated portions are stacked, and which includes tab groups 15 in which the tabs 26 are stacked; conductive members 16a that are parts of terminal structures 16 that connect the electrode assembly 12 and an external device; and a welded portion A where the tab groups 15 and the conductive members 16a are welded. From among the tabs 26 constituting the tab group 15, a tab 26 farthest from the conductive member 16a is a first tab 26a, and a tab 26 adjacent to the first tab 26a is a second tab 26b. The secondary battery includes a joint B in which the first tab 26a and the second tab 26b are joined by a connection layer 29 made of a low melting point conductive material.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a power storage device having a welded portion in which an uncoated portion group and a terminal structure are welded, and a method for manufacturing the power storage device.

  2. Description of the Related Art Conventionally, vehicles such as an EV (Electric Vehicle) and a PHV (Plug in Hybrid Vehicle) are equipped with a lithium ion secondary battery, a nickel hydride secondary battery, or the like as a power storage device for storing power supplied to an electric motor or the like. . The secondary battery disclosed in Patent Literature 1 includes an electrode assembly in which a plurality of electrodes are stacked. The electrode has a metal foil, an active material layer present on at least one surface of the metal foil, and an uncoated portion (core exposed portion) where the active material layer is not present and the metal foil is exposed. The electrode assembly includes an uncoated portion group in which uncoated portions are stacked. The secondary battery includes a terminal structure (a current collecting member) for connecting the electrode assembly and the external device, and a welded portion in which the uncoated portion group and the terminal structure are welded in an overlapping state.

JP 2011-76776 A

  By the way, when all the uncoated portions and the terminal structure are to be welded, the penetration depth of the welded portion needs to be increased as the number of uncoated portions is increased. The penetration depth of the weld can be increased by increasing the heat input during welding. However, if the amount of heat input is excessively increased, among the plurality of uncoated portions constituting the uncoated portion group, the uncoated portion located on the side opposite to the terminal structure and on the heat input side is blown out and the other portions are cut off. In some cases, the uncoated portion that floats up from the uncoated portion and is separated from the terminal structure is not welded to another uncoated portion. That is, poor connection between the uncoated portions occurs. Conversely, when welding so that the uncoated portion away from the terminal structure does not blow out, the penetration depth of the welded portion is insufficient, and the uncoated portion group and the terminal structure cannot be welded well, and the electrode assembly There is a risk that electricity cannot be extracted from the battery.

  SUMMARY An advantage of some aspects of the invention is to provide a power storage device capable of suppressing poor connection between uncoated portions and a method for manufacturing the power storage device.

  The power storage device for solving the above problems is a metal foil, an active material layer present on at least one side of the metal foil, the active material layer does not exist, the uncoated portion where the metal foil is exposed. An electrode assembly comprising an uncoated part group in which a plurality of electrodes having the following are stacked and the uncoated part is stacked; a terminal structure for connecting the electrode assembly to an external device; and the uncoated part. A power storage device comprising: a welded part in which a group of parts and the terminal structure are welded; and an uncoated part that is the most distant from the terminal structure among uncoated parts constituting the uncoated part group. When a portion is a first uncoated portion and an uncoated portion adjacent to the first uncoated portion is a second uncoated portion, at least the first uncoated portion and the second uncoated portion The gist of the present invention is that the part includes a joint part joined by a connection part made of a low melting point conductive material.

  According to this, as a conduction path between the first uncoated part and the second uncoated part, there is a path passing through the welded part and a path passing through the joint part. When forming a welded portion, the first uncoated portion is melted by the heat of welding and rises from the second uncoated portion, so that the first uncoated portion is not welded to another uncoated portion including the second uncoated portion. Sometimes. In this case, the first uncoated portion and the second uncoated portion cannot be connected via the route passing through the welded portion, but the first uncoated portion and the second uncoated portion cannot be connected via the route passing through the joint. Can be connected to the coating unit. In other words, even if the first uncoated portion breaks due to the heat of welding, a conduction path between the first uncoated portion and the second uncoated portion can be secured by the joint. Therefore, poor connection between uncoated portions can be suppressed.

  Regarding the power storage device, when a path along the uncoated part and connecting the welded part and the active material layer at the shortest distance is a virtual path, the joint part is located at least on the virtual path. Is preferred.

  When the first uncoated portion is melted by heat at the time of welding and cannot be connected to the first uncoated portion and the second uncoated portion via a path passing through the welded portion, the first uncoated portion is connected to the first uncoated portion. The second uncoated portion is connected via a path passing through the joint. At this time, if the joint is located outside the virtual path, the path from the active material layer to the terminal structure through the weld and the joint is between the first uncoated part and the second uncoated part. In this case, the length is longer than the path passing through the welded portion by the amount of detour to the joint. Therefore, by arranging the junction on the virtual path, it is possible to prevent the current path between the active material layer and the terminal structure from being lengthened. As a result, an increase in electric resistance in the uncoated part group can be suppressed.

In the above power storage device, it is preferable that the connection portion is a connection layer present in all the uncoated portions constituting the uncoated portion group.
According to this, when the connection layer is present on at least one of the surface on the second uncoated portion side in the first uncoated portion and the surface on the first uncoated portion side in the second uncoated portion. In addition, it is necessary to separately manufacture an uncoated portion having a connection layer and an uncoated portion having no connection layer. On the other hand, when the connection layer exists in all the uncoated portions, the uncoated portion can be manufactured by the same manufacturing method. Therefore, the productivity of the power storage device is improved. Further, when the uncoated portions other than the first uncoated portion and the second uncoated portion are also joined by the connection portion, the cross-sectional area of the current flowing through the uncoated portion group increases, The electric resistance in the group can be reduced.

In the above power storage device, it is preferable that the welding portion includes the low melting point conductive material.
The weld is formed by solidification of the fusion zone. When the fusion zone consists of only one kind of metal element, the fusion zone (liquid) rapidly solidifies and becomes a weld zone (solid), so shrinkage during solidification may cause defects such as shrinkage and voids in the weld zone. There is. On the other hand, when the molten portion contains one kind of metal element and at least one kind of metal element different from the metal element, a solid-liquid coexistence region exists during solidification from the molten part (liquid) to the welded part (solid). The molten portion (liquid) is supplied to the portion that has solidified and shrunk, and solidifies while filling in defects such as shrinkage and voids, and becomes a welded portion (solid). This makes it difficult for defects to occur in the welded portion. Further, the melting point of the fusion zone is lower when the fusion zone contains two or more metal elements than when the fusion zone consists of only one type of metal element. From the above, by forming the welded portion so as to include the low melting point conductive material in addition to the metal element which is the material of the uncoated portion, a welded portion of only the metal element which is the material of the uncoated portion is formed. As compared with the case where the welding is performed, defects in the welded portion can be suppressed, and the penetration depth of the welded portion can be increased without increasing the heat input during welding.

  A method for manufacturing a power storage device for solving the above-described problem includes a metal foil, an active material layer present on at least one surface of the metal foil, and an uncoated metal foil having no active material layer and exposing the metal foil. A plurality of electrodes having a processed part are stacked, and an electrode assembly including an uncoated part group in which the uncoated part is stacked, a terminal structure connecting the electrode assembly and an external device, and A method for manufacturing a power storage device comprising: an uncoated portion group and a welded portion to which the terminal structure is welded, wherein the uncoated portion group and the terminal structure are welded to form the welded portion. Welding step, and among the uncoated parts constituting the uncoated part group, an uncoated part furthest from the terminal structure is defined as a first uncoated part, and is adjacent to the first uncoated part. When the matching uncoated portion is a second uncoated portion, the first uncoated portion is connected by a connecting portion made of a low melting point conductive material. A joining step of joining the second uncoated portion to form a joining portion, wherein the joining portion is formed by melting the connecting portion by heat of the welding process. I do.

  According to this, as a conduction path between the first uncoated part and the second uncoated part, there is a path passing through the welded part and a path passing through the joint part. When forming a welded portion, the first uncoated portion is melted by the heat of welding and rises from the second uncoated portion, so that the first uncoated portion is not welded to another uncoated portion including the second uncoated portion. Sometimes. In this case, the first uncoated portion and the second uncoated portion cannot be connected via the route passing through the welded portion, but the first uncoated portion and the second uncoated portion cannot be connected via the route passing through the joint. Can be connected to the coating unit. In other words, even if the first uncoated portion breaks due to the heat of welding, a conduction path between the first uncoated portion and the second uncoated portion can be secured by the joint. Therefore, poor connection between uncoated portions can be suppressed. In addition, since the joining portion is formed during the welding process, it is not necessary to provide a process for joining the first uncoated portion and the second uncoated portion separately from the welding process.

In the method for manufacturing a power storage device, it is preferable that, in the welding step, the welding portion is formed so as to include the low-melting-point conductive material.
The weld is formed by solidification of the fusion zone. When the fusion zone consists of only one kind of metal element, the fusion zone (liquid) rapidly solidifies and becomes a weld zone (solid), so shrinkage during solidification may cause defects such as shrinkage and voids in the weld zone. There is. On the other hand, when the molten portion contains one kind of metal element and at least one kind of metal element different from the metal, a solid-liquid coexistence region exists during solidification from the molten portion (liquid) to the welded portion (solid), The molten portion (liquid) is supplied to the portion that has solidified and shrunk, and solidifies while filling in defects such as shrinkage and voids, and becomes a welded portion (solid). This makes it difficult for defects to occur in the welded portion. Further, the melting point of the fusion zone is lower when the fusion zone contains two or more metal elements than when the fusion zone consists of only one type of metal element. From the above, by forming the welded portion so as to include the low melting point conductive material, it is possible to suppress defects in the welded portion, and to increase the penetration depth of the welded portion without increasing the heat input during welding. .

  The method for manufacturing a power storage device may include an electrode material manufacturing step of manufacturing an electrode material to be a material of the electrode, and an electrode manufacturing step including a cutting step of cutting the electrode material to form the electrode. A laminating step of laminating the electrodes produced by an electrode producing step to produce the electrode assembly, wherein the electrode material producing step comprises applying an active material mixture to a long strip-shaped metal foil material. A first coating step of forming a first coating portion by applying a low melting point conductive material to the metal foil material to form a second coating portion. In the step, the metal foil is formed by the metal foil material, the active material layer is formed by the first coated portion, and the connection portion is formed in the uncoated portion by the second coated portion. Is preferred.

  According to this, all the electrodes constituting the electrode assembly can be manufactured by the same manufacturing method, and even if any uncoated part becomes the first uncoated part or the second uncoated part, the first uncoated part becomes the first uncoated part. The uncoated portion and the second uncoated portion can be joined by the connecting portion. Therefore, the productivity of the power storage device is improved. In addition, since the connection portion can be formed in the uncoated portion only by adding the second coating process to the existing first coating process, the electrode manufacturing process and manufacturing equipment do not need to be significantly changed. .

  According to the present invention, poor connection between uncoated portions can be suppressed.

FIG. 2 is an exploded perspective view of the secondary battery according to the first embodiment. FIG. 3 is an exploded perspective view of the electrode assembly. FIG. 4 is a cross-sectional view of a secondary battery. (A) is sectional drawing which shows a joining part and a welding part, (b) is a top view which shows a joining part and a welding part. FIG. 4 is a plan view showing a method for manufacturing an electrode. FIG. 6 is a sectional view of a secondary battery according to a second embodiment. FIG. 3 is an exploded perspective view of the electrode assembly. Sectional drawing which shows a joining part and a welding part. Sectional drawing which shows another example of an electrode assembly. Sectional drawing which shows another example of a joining part.

(First embodiment)
Hereinafter, a first embodiment in which a power storage device and a method for manufacturing the power storage device are embodied as a secondary battery and a method for manufacturing a secondary battery will be described with reference to FIGS. 1 to 5.

  As shown in FIG. 1, a secondary battery 10 as a power storage device includes a case 11 and an electrode assembly 12 housed in the case 11. The case 11 has a rectangular parallelepiped case body 13 and a rectangular flat lid 14 for closing the opening 13 a of the case body 13. The case body 13 and the lid 14 constituting the case 11 are both made of metal (for example, stainless steel or aluminum). The secondary battery 10 of the present embodiment is a prismatic battery having a rectangular appearance. Further, the secondary battery 10 of the present embodiment is a lithium ion battery.

  As shown in FIG. 2, the electrode assembly 12 includes a positive electrode 21 as a plurality of electrodes, a negative electrode 22 as a plurality of electrodes, and a plurality of separators 23. The electrode assembly 12 has a layered structure in which a separator 23 is interposed between a positive electrode 21 and a negative electrode 22 and is insulated from each other. The direction in which the positive electrode 21 and the negative electrode 22 are stacked is referred to as a stacking direction.

  The positive electrode 21 has a positive metal foil (for example, an aluminum foil) 24 as a rectangular sheet-shaped metal foil, and a positive electrode active material layer 25 as an active material layer present on both surfaces of the positive metal foil 24. The positive electrode 21 has a rectangular positive electrode tab 26 protruding from a part of one side of the positive metal foil 24. The tab 26 of the positive electrode has no positive electrode active material layer 25 and is an uncoated portion formed of the positive electrode metal foil 24 itself. The longitudinal direction of the tab 26 coincides with the direction in which the tab 26 protrudes from one side of the positive electrode metal foil 24, and the short direction of the tab 26 coincides with the direction along one side of the positive electrode metal foil 24 from which the tab 26 protrudes. The amount of protrusion of the tab 26 from one side of the positive metal foil 24 is substantially the same for all the positive electrodes 21.

  The negative electrode 22 includes a negative electrode metal foil (for example, copper foil) 27 as a rectangular sheet-shaped metal foil and a negative electrode active material layer 28 as an active material layer present on both surfaces of the negative electrode metal foil 27. The negative electrode 22 has a rectangular negative electrode tab 26 protruding from a part of one side of the negative electrode metal foil 27. The tab 26 of the negative electrode is an uncoated portion formed of the negative electrode metal foil 27 itself without the negative electrode active material layer 28. The longitudinal direction of the tab 26 coincides with the direction in which the tab 26 protrudes from one side of the negative electrode metal foil 27, and the short direction of the tab 26 coincides with the direction along one side of the negative electrode metal foil 27 from which the tab 26 protrudes. The amount of protrusion of the tab 26 from one side of the negative metal foil 27 is substantially the same for all the negative electrodes 22.

  Each of the positive electrodes 21 and the negative electrodes 22 has a connection layer 29 as a connection part existing on one surface of the tab 26 before being stacked as the electrode assembly 12. The connection layer 29 of the present embodiment is made of a brazing material as a low melting point conductive material. As the brazing material, for example, brazing materials such as JIS4004, JIS4343, and JIS4045 are used. The connection layer 29 is located at the center in the longitudinal direction of the tab 26 and in the entire short direction of the tab 26. The position of the connection layer 29 in the longitudinal direction of the positive electrode tab 26 is substantially the same for all the positive electrodes 21 constituting the electrode assembly 12, and the position of the connection layer 29 in the longitudinal direction of the negative electrode tab 26 is This is substantially the same for all the negative electrodes 22 constituting the solid 12.

  As shown in FIGS. 1 and 3, the electrode assembly 12 includes a tab group 15 as a group of uncoated portions of the positive electrode on which tabs 26 of each positive electrode 21 are laminated, and a tab 26 of each negative electrode 22. And a tab group 15 as a group of uncoated portions of the negative electrode. The electrode assembly 12 is accommodated in the case 11 with the tab groups 15 bent. In the tab group 15, the tabs 26 and the connection layers 29 are alternately stacked. In other words, the connection layer 29 exists between the adjacent tabs 26. As will be described later, when the positive electrode 21 and the negative electrode 22 are stacked as the electrode assembly 12, the connection layer 29 forms a part of a joint portion where the adjacent tabs 26 are joined.

  As shown in FIG. 3, in the present embodiment, the tabs 26 are collected and laminated on one end side in the laminating direction. For this reason, the tip of the tab 26 of the positive electrode 21 located at one end in the stacking direction protrudes from the tip of the tab 26 of the positive electrode 21 located at the other end in the stacking direction. Similarly, the tip of the tab 26 of the negative electrode 22 located at one end in the stacking direction protrudes from the tip of the tab 26 of the negative electrode 22 located at the other end in the stacking direction. Therefore, on the tip end side of each tab group 15, the tips of the tabs 26 are arranged stepwise in the longitudinal direction of the tabs 26. In each connection layer 29, the connection layer 29 existing on the tab 26 of the positive electrode 21 located on one end side in the stacking direction is connected to the connection layer 29 existing on the tab 26 on the other end side in the stacking direction. It is located on the tip side of the tab group 15 with respect to the layer 29. Similarly, the connection layer 29 present on the tab 26 of the negative electrode 22 located on one end side in the stacking direction is a group of tabs smaller than the connection layer 29 existing on the tab 26 of the negative electrode 22 located on the other end side in the stacking direction. 15 is located on the tip side. Therefore, in each tab group 15, the connection layers 29 are arranged stepwise in the longitudinal direction of the tab 26.

  As shown in FIG. 1, the secondary battery 10 includes a terminal structure 16 of each polarity for extracting electricity from the electrode assembly 12. In the present embodiment, the positive electrode terminal structure 16 is made of aluminum, and the negative electrode terminal structure 16 is made of copper. The positive electrode terminal structure 16 has a rectangular plate-shaped conductive member 16a joined to the positive electrode tab group 15, and a rod-shaped electrode terminal 16b connected to the conductive member 16a. The negative electrode terminal structure 16 has a rectangular plate-shaped conductive member 16a joined to the negative electrode tab group 15, and a rod-shaped electrode terminal 16b connected to the conductive member 16a. The positive electrode terminal structure 16 is electrically connected to the electrode assembly 12 via the positive electrode tab group 15, and the negative electrode terminal structure 16 is electrically connected to the electrode assembly 12 via the negative electrode tab group 15. Have been. As shown in FIG. 3, the tip of each electrode terminal 16 b protrudes outside the case 11 through the through hole 14 a of the lid 14. An insulating ring 17 for insulating the lid 14 is attached to each of the electrode terminals 16b.

  As shown in FIGS. 3, 4A and 4B, the secondary battery 10 is laser-welded with the tab group 15 having the same polarity and the conductive member 16a of the terminal structure 16 being overlapped. The welding portion A is provided. FIGS. 4A and 4B show the tab group 15 before bending. Of the plurality of tabs 26 constituting the tab group 15, the tab 26 located at one end in the stacking direction is opposed to the end surface of the conductive member 16a opposite to the electrode terminal 16b, and is located at the other end in the stacking direction. 26 is farthest from the conductive member 16a. The welded portion A is located on the tip end side of the tab group 15 with respect to the connection layers 29 arranged in a stepwise manner in the longitudinal direction of the tab 26.

  The secondary battery 10 includes a plurality of joints B in which adjacent tabs 26 in the tab group 15 are joined by a connection layer 29. Of the plurality of tabs 26 constituting the tab group 15, the tab 26 farthest from the conductive member 16a is a first tab 26a as a first uncoated portion, and the tab 26 adjacent to the first tab 26a is a second tab 26a. The second tab 26b is used as a coating part. Among the plurality of joints B, the joint B in which the first tab 26a and the second tab 26b are joined by the connection layer 29 of the second tab 26b is referred to as the other end joint B1. In addition, as shown in FIG. 4B, a path along the first tab 26 a of the positive electrode and connecting the welded portion A and the positive electrode active material layer 25 at the shortest distance is defined as a virtual path R. Similarly, a path along the first tab 26a of the negative electrode and connecting the welded portion A and the negative electrode active material layer 28 at the shortest distance is defined as a virtual path R. The other end side joining portion B1 is located on the virtual route R. The current path between the first tab 26a and the second tab 26b includes a path passing through the welded portion A and a path passing through the other end side joint portion B1.

Next, a method for manufacturing the secondary battery 10 of the first embodiment will be described.
The method of manufacturing the secondary battery 10 includes an electrode material manufacturing step of manufacturing an electrode material 40 to be a material of the positive electrode 21 and the negative electrode 22, and a cutting step of cutting the electrode material 40 to form the positive electrode 21 and the negative electrode 22. And an electrode manufacturing step. Although the electrode manufacturing process for manufacturing the positive electrode 21 will be described in detail, the manufacturing of the negative electrode 22 is performed in the same manner.

  As shown in FIG. 5, in the electrode material manufacturing process, a positive electrode active material mixture is applied to a long strip-shaped metal foil material 41 that can form the positive electrode metal foil 24, and the positive electrode active material layer 25 can be formed. A first coating step for forming the first coating section 42 is provided. The first coating portion 42 is formed on both surfaces of the metal foil material 41 and is formed over the entire length of the metal foil material 41. Further, the first coating portion 42 is formed with a constant width on one end side in the short direction of the metal foil material 41. The metal foil material 41 does not have the first coating portion 42, and has an exposed portion 41a where the metal foil material 41 is exposed.

  The electrode material manufacturing step includes a second coating step of coating a brazing material on the exposed portion 41 a of the metal foil material 41 to form a second coating portion 43 on which the connection layer 29 can be formed. The second coating portion 43 is formed on one surface of the exposed portion 41 a of the metal foil material 41 and is formed over the entire length of the metal foil material 41 in the longitudinal direction. Further, the second coating portion 43 is formed to have a constant width near the center in the short direction of the exposed portion 41a. Thereby, the electrode material 40 is completed.

  In the cutting step, the electrode material 40 is cut along the shape of the positive electrode 21 shown by a two-dot chain line in FIG. Thereby, the tab 26 is formed from the exposed portion 41a while being formed from the positive metal foil 24 from the metal foil material 41. In addition, the positive electrode active material layer 25 is formed from the first coating unit 42, and the connection layer 29 is formed from the second coating unit 43. Thus, the positive electrode 21 is formed.

  In addition to the above-described steps, the electrode material manufacturing step includes a pressing step for increasing the density of the active material in the positive electrode active material layer 25, and removal of the solvent remaining in the active material mixture in the first coating unit 42. May be included. The pressing step and the drying step are known as the manufacturing steps of the secondary battery, and thus detailed description is omitted.

  The method of manufacturing the secondary battery 10 includes a laminating step of forming the electrode assembly 12, a foil collecting step of forming the tab group 15 by collecting the tabs 26, and welding the tab group 15 and the conductive member 16a. And a joining step of joining the tabs 26 together by the connection layer 29 to form the joint B, and an accommodation step of accommodating the electrode assembly 12 in the case 11.

  In the laminating step, lamination is performed with the separator 23 interposed between the positive electrode 21 and the negative electrode 22 and insulated from each other. Thereby, the electrode assembly 12 is formed. In the foil collecting step, all the tabs 26 of the electrode assembly 12 are arranged on the conductive member 16a of the terminal structure 16, and all the tabs 26 are pressed from the opposite side of the conductive member 16a across the tab 26. Thereby, all the tabs 26 are collected on one end side in the stacking direction, and the tab group 15 is formed. Of the plurality of tabs 26 constituting the tab group 15, the tab 26 located at one end in the stacking direction is formed. It faces the conductive member 16a. The connection layer 29 is located between the tabs 26.

  In the welding step, first, the tab group 15 is pressed toward the conductive member 16a by a jig (not shown) arranged above the tab group 15. The portion pressed in the tab group 15 is a portion surrounding the portion to be the welded portion A later, and the portion to be the welded portion A in the tab group 15 is not pressed and is exposed. As a result, the tab 26 and the connection layer 29 come into close contact, and the tab 26 located at one end in the stacking direction and the conductive member 16a come into close contact. Next, in a state where the tab group 15 is pressed by the jig, laser is irradiated from the first tab 26a side of the tab group 15 toward the tab group 15 and the conductive member 16a by a laser irradiation device (not shown). The laser irradiation device of the present embodiment moves from one end in the longitudinal direction of the conductive member 16a to the other end while irradiating the laser.

  In the portion of the tab group 15 where the laser is irradiated and in the vicinity thereof, the melting of the tab group 15 rapidly progresses, and the molten metal is pushed out by the recoil of the metal vapor to form a keyhole. The laser penetrates into the formed keyhole and undergoes multiple reflections within the keyhole. Thereby, the depth of the keyhole is further increased. Then, when the deepest part of the keyhole reaches the conductive member 16a, a fused portion where the tab group 15 and the conductive member 16a are melted is formed. After the laser beam passes, the molten portion solidifies, thereby forming a welded portion A in which the tab group 15 and the conductive member 16a are welded. The keyhole formed by the laser irradiation is filled by the surface tension of the molten metal before the molten portion solidifies to become the welded portion A. In the present embodiment, the laser irradiation condition is set to a condition that the laser does not penetrate the conductive member 16a. The laser irradiation conditions refer to the output of the laser, the spot diameter, the position of the focal point in the thickness direction of the conductive member 16a, the moving speed of the laser irradiation device, and the like.

  In the welding process, the laser does not directly act on the connection layer 29 located between the tabs 26, but heat generated by laser welding is transmitted to the entire tab 26 by heat conduction from a portion irradiated with the laser. Due to the laser welding, the connection layer 29 is melted by heat transmitted through the entire tab 26 by heat conduction, and the tabs 26 are joined to each other by the melted connection layer 29. That is, the joining process is performed during the welding process. Specifically, the first tab 26a is joined to the connection layer 29 located between the first tab 26a and the second tab 26b, so that the first tab 26a and the second tab 26b are joined by the connection layer 29. Joined. The other tabs 26 are similarly joined. As a result, a joint B in which the tabs 26 are joined by the connection layer 29 is formed.

  In the accommodation step, the tab group 15 is bent, and the electrode assembly 12 is inserted into the case body 13. Next, the electrode terminals 16 b of each terminal structure 16 are inserted into the through holes 14 a of the lid 14, and the opening 13 a of the case body 13 is closed by the lid 14. Then, the case body 13 and the lid 14 are joined by welding. Thereby, the secondary battery 10 is completed.

The operation and effect of the first embodiment will be described.
(1-1) As a conduction path between the first tab 26a and the second tab 26b, there is a path that passes through the welded portion A and a path that passes through the joint portion B. When forming the welded portion A, the first tab 26a may not be welded to other tabs 26 including the second tab 26b by being blown out by the heat of welding and rising from the second tab 26b. In this case, the first tab 26a and the second tab 26b cannot be connected via a path passing through the welded portion A, but the first tab 26a and the second tab 26b are connected via a path passing through the joint B. it can. That is, even if the first tab 26a is broken by the heat at the time of welding, the conduction path between the first tab 26a and the second tab 26b can be secured by the joint B. Therefore, poor connection between the tabs 26 can be suppressed. As a result, all of the positive electrode 21 and the negative electrode 22 are electrically connected to the terminal structure 16, and a decrease in the output of the secondary battery 10 can be suppressed. Further, the joint portion B is formed by melting the connection layer 29 by heat when forming the weld portion A. Therefore, there is no need to provide a step for joining the first tab 26a and the second tab 26b separately from the welding step.

  (1-2) When the first tab 26a cannot be connected to the second tab 26b via the path passing through the welded portion A due to the fusing of the first tab 26a by heat during welding, The second tab 26b is connected to the second tab 26b via a path passing through the joint B. At this time, when the joining portion B is located outside the virtual route R, the route from the positive electrode active material layer 25 or the negative electrode active material layer 28 to the conductive member 16a through the welding portion A and the joining portion B is the first tab. The length of the detour to the joint B between the second tab 26a and the second tab 26b is longer than the path passing through the weld A. Therefore, by disposing the joint portion B on the virtual path R, it is possible to prevent the energization path between the positive electrode active material layer 25 or the negative electrode active material layer 28 and the conductive member 16a from being lengthened. As a result, an increase in electric resistance in the tab group 15 can be suppressed.

  (1-3) For example, when the connection layer 29 exists only on the surface of the second tab 26b on the side of the first tab 26a, the positive electrode 21 or the negative electrode 22 having the connection layer 29 and the connection layer 29 are not provided. It is necessary to manufacture the positive electrode 21 or the negative electrode 22 separately. On the other hand, when the connection layers 29 are present on all the tabs 26 as in the present embodiment, all the positive electrodes 21 or the negative electrodes 22 constituting the electrode assembly 12 can be manufactured by the same manufacturing method. Also, whichever tab 26 becomes the first tab 26a or the second tab 26b, the first tab 26a and the second tab 26b can be joined. Therefore, the productivity of the secondary battery 10 is improved.

  Further, when the tabs 26 other than the first tab 26a and the second tab 26b are also joined to each other by the connection layer 29, the cross-sectional area of the current flowing through the tab group 15 increases, so that the electric resistance in the tab group 15 can be reduced.

  Further, in the method for manufacturing the secondary battery 10 of the present embodiment, the connection layer 29 is formed on the tab 26 by adding the second coating process to the existing first coating process, so The process and manufacturing equipment do not need to be changed significantly.

(Second embodiment)
Hereinafter, a second embodiment in which a power storage device and a method for manufacturing the power storage device are embodied as a secondary battery and a method for manufacturing a secondary battery will be described with reference to FIGS. 6 to 8. In addition, about the structure similar to 1st Embodiment, description is abbreviate | omitted and the same code | symbol is attached.

  As shown in FIG. 7, the electrode assembly 12 includes a strip-shaped separator 23, a strip-shaped positive electrode 21, a strip-shaped separator 23, and a strip-shaped negative electrode 22, which are stacked in this order and wound. FIG. The electrode assembly 12 has a layered structure in which a positive electrode 21, a negative electrode 22, and a separator 23 are stacked.

  The positive electrode 21 includes a strip-shaped positive metal foil 24, a positive electrode active material layer 25 existing on both surfaces of the positive metal foil 24, and an uncoated portion 30 existing on one end in the short direction of the positive metal foil 24. Have. The uncoated portion 30 does not have the positive electrode active material layer 25 and is composed of the positive electrode metal foil 24 itself. Further, the negative electrode 22 includes a strip-shaped negative electrode metal foil 27, a negative electrode active material layer 28 present on both surfaces of the negative electrode metal foil 27, and an uncoated portion 30 existing on one end side in the short direction of the negative electrode metal foil 27. And The uncoated portion 30 does not have the negative electrode active material layer 28 and is constituted by the negative electrode metal foil 27 itself. The uncoated portion 30 exists over the entire length of the positive electrode 21 and the negative electrode 22 in the longitudinal direction. Before being wound as the electrode assembly 12, the positive electrode 21 and the negative electrode 22 each have a connection layer 29 as a connection portion existing in a band shape on one surface of the uncoated portion 30. The connection layer 29 of the present embodiment is made of a brazing material as a low melting point conductive material.

  As shown in FIG. 6, the electrode assembly 12 includes a positive electrode uncoated portion group 31 in which a positive electrode uncoated portion 30 is laminated on one end of the winding axis, and the other end of the winding axis. A negative electrode uncoated portion group 31 in which a negative electrode uncoated portion 30 is laminated. As shown in FIG. 8, the uncoated portion group 31 has a layered structure in which the uncoated portions 30 and the connection layers 29 are alternately stacked. In other words, the connection layer 29 exists between the uncoated portions 30. As will be described later, when the positive electrode 21 and the negative electrode 22 are wound as the electrode assembly 12, the connection layer 29 forms a part of a joining portion where the adjacent uncoated portions 30 are joined.

  As shown in FIG. 6, the secondary battery 10 includes a terminal structure 16 of each polarity for extracting electricity from the electrode assembly 12. Each of the terminal structures 16 includes a conductive member 16a, an electrode terminal 16b protruding from the conductive member 16a, an extension 16c extending from the electrode terminal 16b toward the electrode assembly 12, and a tip end of the extension 16c. The connection piece 16d has a rectangular plate shape.

  As shown in FIG. 8, the secondary battery 10 includes a welded portion A that is laser-welded in a state where the uncoated portion group 31 having the same polarity and the connection piece 16 d of the terminal structure 16 are overlapped. A part of the outermost uncoated portion 30 of the uncoated portion group 31 faces the connection piece 16 d of the terminal structure 16. The welded portion A of the present embodiment is also formed in a portion where the connection layer 29 is located in the uncoated portion group 31. Therefore, the welded portion A includes the brazing material.

  The secondary battery 10 includes a plurality of joints B in which the adjacent uncoated portions 30 in the uncoated portion group 31 are joined by the connection layer 29. In the uncoated portion 30, a portion located at the outermost periphery and farthest from the connection piece 16d is defined as a first uncoated portion 30a, and is adjacent to the first uncoated portion 30a and is located at the first uncoated portion 30a. The portion located on the inner peripheral side is also referred to as a second uncoated portion 30b. Out of the plurality of joints B, a joint B in which the first uncoated portion 30a and the second uncoated portion 30b are joined by the connection layer 29 is referred to as an outer joint B1. As the energization paths of the first uncoated portion 30a and the second uncoated portion 30b, there are a route passing through the welded portion A and a route passing through the outer joint portion B1.

Next, a method for manufacturing the secondary battery 10 of the second embodiment will be described.
The method for manufacturing the secondary battery 10 includes an electrode manufacturing process for manufacturing the positive electrode 21 and the negative electrode 22. If the cutting process is omitted from the electrode manufacturing process of the first embodiment, the process will be the electrode manufacturing process of the second embodiment, and the description of the electrode manufacturing process will be omitted. In the electrode material process, the positive metal foil 24 is formed from the metal foil material 41, and the uncoated portion 30 is formed from the exposed portion 41a. In addition, the positive electrode active material layer 25 is formed from the first coating unit 42, and the connection layer 29 is formed from the second coating unit 43. Thus, the positive electrode 21 is formed.

  The method of manufacturing the secondary battery 10 includes a laminating step of forming the electrode assembly 12, a foil collecting step of collecting the uncoated portions 30 to form the uncoated portion group 31, A welding step of welding the group 31 and the connecting piece 16d to form a welded portion A, a joining process of joining the uncoated portions 30 together by the connecting layer 29 to form a joined portion B, and a process of joining the electrode assembly 12 And a housing step of housing the case 11. Note that the accommodating step is performed by a method substantially similar to that of the first embodiment, and a description thereof will be omitted.

  In the laminating step, the separator 23, the positive electrode 21, the separator 23, and the negative electrode 22 are laminated and wound in this order. At this time, the uncoated portion 30 of the positive electrode 21 is disposed so as to protrude from one end of the separator 23 in the short direction, and the uncoated portion 30 of the negative electrode 22 is positioned from the other end of the separator 23 in the short direction. It is arranged to protrude. Thereby, the electrode assembly 12 is formed.

  In the foil collecting step, the uncoated portion 30 wound around the connection piece 16d of the terminal structure 16 is overlapped, and the uncoated portion 30 is pressed from the opposite side of the connection piece 16d with the uncoated portion 30 interposed therebetween. Thereby, the wound uncoated portion 30 is collected near the connection piece 16d to form the uncoated portion group 31, and a part of the outermost portion of the uncoated portion 30 Faces the connection piece 16d. The uncoated portion group 31 has a layered structure in which the uncoated portions 30 and the connection layers 29 are alternately laminated, and the connection layer 29 is located between the uncoated portions 30.

  In the welding step, first, the uncoated part group 31 is pressed toward the connection piece 16 d of the terminal structure 16 by a jig (not shown) arranged on the uncoated part group 31 side. The portion to be pressed in the uncoated portion group 31 is a portion surrounding the portion to be the welded portion A later, and the portion to be the welded portion A in the uncoated portion group 31 is not pressed and is exposed. . Thus, the uncoated portion 30 and the connection layer 29 are in close contact with each other, and the outermost uncoated portion 30 in the uncoated portion group 31 and the connection piece 16d are in close contact with each other.

  Next, in a state where the uncoated portion group 31 is pressed by the jig, the uncoated portion group 31 and the connection piece 16d are directed from the first uncoated portion 30a side of the tab group 15 by a laser irradiation device (not shown). To irradiate the laser. The laser irradiation device of the present embodiment moves from one end in the longitudinal direction of the connection piece 16d to the other end while irradiating the laser. As a result, a fused portion in which the uncoated portion group 31, the connection layer 29, and the connection piece 16d are melted is formed. After the laser beam passes, the melted portion solidifies to form a welded portion A in which the uncoated portion group 31 and the connection piece 16d are welded. The welded portion A includes a brazing material, which is a material of the connection layer 29, in addition to the material of the uncoated portion 30 and the connection piece 16d.

  In the welding process, the laser does not directly act on the connection layer 29 located between the uncoated portions 30, but the heat generated by the laser welding causes the uncoated portion 30 by heat conduction from the portion irradiated with the laser. It is transmitted throughout. The connection layer 29 is melted by heat transmitted to the entire uncoated portion 30 by heat conduction due to the laser welding, and the uncoated portions 30 are joined to each other by the melted connection layer 29. That is, the joining process is performed during the welding process. Specifically, the first uncoated portion 30a and the second uncoated portion 30b are joined via the connection layer 29 by joining the fused connection layer 29 and the second uncoated portion 30b. . The other parts of the uncoated part 30 are similarly joined. As a result, a joint portion B in which the uncoated portions 30 are joined to each other by the connection layer 29 is formed.

The operation and effect of the second embodiment will be described.
(2-1) As a conduction path between the first uncoated portion 30a and the second uncoated portion 30b, there are a route passing through the welded portion A and a route passing through the joint portion B. When forming the welded portion A, the first uncoated portion 30a is melted off by the heat of welding and rises from the second uncoated portion 30b, thereby forming another uncoated portion including the second uncoated portion 30b. It may not be welded to the engineered part 30. In this case, the first uncoated portion 30a and the second uncoated portion 30b cannot be connected via a path passing through the welded portion A, but the first uncoated portion 30a is not connected via a route passing through the joint B. 30a and the 2nd uncoated part 30b can be connected. In other words, even if the first uncoated portion 30a is broken by the heat of welding, the joining portion B can secure a conduction path between the first uncoated portion 30a and the second uncoated portion 30b. Therefore, poor connection between the uncoated portions 30 can be suppressed. As a result, even if the first uncoated portion 30a is blown out, the length of the conduction path between the first uncoated portion 30a and the connection piece 16d of the terminal structure 16 is suppressed, and the uncoated portion group 31 is suppressed. Can be suppressed from increasing in electric resistance.

  (2-2) The connection layer 29 is present over the entire uncoated portion 30 in the longitudinal direction. Therefore, no matter which part of the uncoated part 30 becomes the first uncoated part 30a or the second uncoated part 30b, the first uncoated part 30a and the second uncoated part 30b are connected. It can be joined by layer 29. Therefore, it is not necessary to adjust the formation position of the second coated portion 43 with respect to the metal foil material 41 so that the connection layer 29 is located between the first uncoated portion 30a and the second uncoated portion 30b. Therefore, the productivity of the secondary battery 10 improves. In the method for manufacturing the secondary battery 10 of the present embodiment, the connection layer 29 is formed on the uncoated portion 30 by adding the second coating process to the existing first coating process. The electrode manufacturing process and manufacturing equipment need not be changed significantly.

  (2-3) The welded portion A is formed by solidification of the molten portion. When the molten portion is composed of only one kind of metal element, the molten portion (liquid) rapidly solidifies and becomes a welded portion A (solid). Therefore, shrinkage during solidification causes defects such as shrinkage and voids in the welded portion A. May occur. On the other hand, when the molten portion contains a metal element and at least one element different from the metal element, a solid-liquid coexistence region exists during solidification from the molten portion (liquid) to the welded portion A (solid). The molten portion (liquid) is supplied to the portion that has solidified and shrunk, and solidifies while filling in defects such as shrinkage and voids, and becomes a welded portion A (solid). Thereby, a defect is less likely to occur in the welded portion A. Further, the melting point of the fusion zone is lower when the fusion zone contains two or more metal elements than when the fusion zone consists of only one type of metal element. From the above, by forming the welded portion A so as to include the brazing material in addition to the metal element as the material of the uncoated portion 30, the welded portion A containing only the metal element as the material of the uncoated portion 30 is formed. As compared with the case of forming a weld, the defect of the welded portion A can be suppressed, and the penetration depth of the welded portion A can be increased without increasing the heat input during welding.

The first and second embodiments can be modified and implemented as follows. The present embodiment and the modifications can be implemented in combination with each other within a technically consistent range.
In the first and second embodiments, in the positive electrode 21, the positive electrode active material layer 25 may exist on one surface of the positive electrode metal foil 24. Similarly, in the negative electrode 22, the negative electrode active material layer 28 may be present on one surface of the negative electrode metal foil 27.

In the first embodiment, the connection layers 29 may be present on both sides of the tab 26. Similarly, in the second embodiment, the connection layers 29 may be present on both surfaces of the uncoated portion 30.
In the second embodiment, the connection piece 16d of the terminal structure 16 may be inserted into the electrode assembly 12 so as to be a winding axis of the electrode assembly 12, and may be welded to the uncoated portion group 31.

In the first and second embodiments, the method of forming the welded portion A is not limited to laser welding. For example, the welded portion A may be formed by ultrasonic welding or resistance welding.
In the first and second embodiments, the material of the terminal structure 16 is not limited to aluminum and copper. The material of the terminal structure 16 may be any material having high conductivity and high strength, such as nickel and stainless steel.

  In the first and second embodiments, the low melting point conductive material that is the material of the connection layer 29 is not limited to the brazing material. The low-melting-point conductive material may be appropriately changed as long as it is made of two or more elements and has a solid-liquid coexistence region in the phase diagram.

  The low-melting-point conductive material may be, for example, a mixture of a non-corrosive fluoride flux based on aluminum potassium fluoride and silicon powder. As the non-corrosive flux, for example, NOCOLOK (registered trademark) can be used. In addition, the low-melting-point conductive material may be, for example, a composite material in which another material is added to aluminum, nickel, stainless steel, or the like. High conductivity can be obtained by using a conductive paste such as silver or carbon at the time of compounding. Note that the melting point of the low melting point conductive material does not need to be lower than the melting points of the materials of the tab 26 and the uncoated portion 30. For example, a silicon powder as a low melting point conductive material may be arranged on the tab 26. In this case, the melting point of the tab 26 is lowered by the diffusion of silicon due to the heat of welding, and the tabs 26 are joined to each other. It is preferable to mix a conductive aid such as a conductive filler with the low melting point conductive material.

  In the first embodiment, as shown in FIG. 9, the tab group 15 may be formed by collecting a plurality of tabs 26 at the center in the stacking direction. In this case, the tip of the tab 26 of the positive electrode 21 located at the center in the stacking direction projects more than the tip of the tab 26 of the positive electrode 21 located at the end in the stacking direction. Similarly, the tip of the tab 26 of the negative electrode 22 located at the center in the stacking direction projects more than the tip of the tab 26 of the negative electrode 22 located at the end in the stacking direction. Therefore, on the tip side of the tab group 15, the tips of the tabs 26 are arranged in a mountain shape such that the apex is located at the center in the stacking direction.

  Also, regarding the connection layer 29, the connection layer 29 existing on the tab 26 of the positive electrode 21 located at the center in the stacking direction is higher than the connection layer 29 existing on the tab 26 of the positive electrode 21 located at the end in the stacking direction. It is located on the tip side of the tab group 15. Similarly, the connection layer 29 present on the tab 26 of the negative electrode 22 located at the center in the stacking direction is more distal than the connection layer 29 existing on the tab 26 of the negative electrode 22 located at the end in the stacking direction. Located on the side. Therefore, in the tab group 15, the connection layers 29 are arranged in a mountain shape such that the apex is located at the center in the stacking direction.

  Even in such a case, the secondary battery 10 includes a welded portion A in which the tab group 15 and the conductive member 16a are welded, and a joint B in which the tabs 26 are joined by the connection layer 29. The welded portion A may be formed at a position that does not overlap with the connection layers 29 arranged in a mountain shape, as shown in FIG. 9, or not shown, but may be formed at a position that overlaps a part of the connection layers 29 arranged in a mountain shape. May be formed. However, the connection layer 29 does not overlap with the entire connection layer 29 located between the first tab 26a and the second tab 26b or between the first uncoated portion 30a and the second uncoated portion 30b. Shall be. When the welded portion A is formed at a position overlapping with a part of the connection layer 29 arranged in a mountain shape, the welded portion A includes a brazing material.

  In the first embodiment, the joint B may be located around the weld A. For example, the joint portion B may be located so as to surround the welded portion A when the tab group 15 is viewed from the direction in which the tabs 26 are stacked.

  In the first and second embodiments, the method of forming the connection portion for joining the tabs 26 or the uncoated portions 30 may be appropriately changed. For example, the connection layer 29 may be formed by screen printing or spraying a low melting point conductive material on the tab 26 or the uncoated portion 30. Further, for example, the connection layer 29 may be formed by immersing the tab 26 or the uncoated portion 30 in a low-melting-point conductive material. Further, for example, a sheet-like low melting point conductive material may be arranged between the tabs 26 or between the uncoated portions 30.

  In the first embodiment, if the first tab 26a and the second tab 26b are joined by the connection layer 29, the other tabs 26 may not be joined by the connection layer 29. As shown in FIG. 10, it is preferable that, of the plurality of tabs 26 constituting the tab group 15, about one third of the tabs 26 near the first tab 26 a are joined by the connection layer 29. In this case, the first tab 26a and the second tab 26b are joined by the connection layer 29 before the first tab 26a is blown out by heat during welding, so that the first tab 26a rises from the second tab 26b. Can be suppressed.

  In the second embodiment, if the first uncoated portion 30a and the second uncoated portion 30b are joined by the connection layer 29, the other uncoated portions 30 are joined by the connection layer 29. It does not have to be done. Of the plurality of uncoated portions 30 constituting the uncoated portion group 31, it is preferable that approximately one third of the tabs 26 near the first uncoated portion 30 a be joined by the connection layer 29. In this case, the first uncoated portion 30a and the second uncoated portion 30b are joined by the connection layer 29 before the first uncoated portion 30a is blown out by heat during welding. It is possible to prevent the coated portion 30a from rising from the second uncoated portion 30b.

  The secondary battery 10 may be a lithium ion secondary battery or another secondary battery. In short, any material may be used as long as ions move between the positive electrode active material and the negative electrode active material and transfer charges.

  The power storage device can be applied to a power storage device other than a secondary battery, such as a capacitor.

DESCRIPTION OF SYMBOLS 10 ... Secondary battery as a power storage device, 12 ... Electrode assembly, 15 ... Tab group as an uncoated part group, 16 ... Terminal structure, 21 ... Positive electrode as an electrode, 22 ... Negative electrode as an electrode, 24 ... Positive electrode metal foil as metal foil, 25 ... Positive electrode active material layer as active material layer, 26 ... Tab as uncoated part, 26a ... First tab as first uncoated part, 26b ... 2nd tab as a coating part, 29 ... connection layer as a connection part, 30 ... uncoated part, 30a ... first uncoated part, 30b ... second uncoated part, 31 ... uncoated part group , 40 ... electrode material, 41 ... metal foil material, 42 ... first coating part, 43 ... second coating part, A ... welding part, B ... joining part, R ... virtual path.

Claims (7)

A plurality of electrodes having a metal foil, an active material layer present on at least one surface of the metal foil, and an uncoated portion where the active material layer is not present and the metal foil is exposed are stacked, and An electrode assembly including an uncoated part group in which a coating part is laminated,
A terminal structure for connecting the electrode assembly and an external device,
A welded portion where the uncoated portion group and the terminal structure are welded,
A power storage device comprising:
Among the uncoated parts constituting the uncoated part group, the uncoated part furthest from the terminal structure is defined as a first uncoated part, and the uncoated part adjacent to the first uncoated part Is the second uncoated part,
At least the first uncoated portion and the second uncoated portion include a joint portion joined by a joint portion made of a low-melting-point conductive material. Along the uncoated portion, and when a route connecting the welded portion and the active material layer at the shortest distance is a virtual route,
The power storage device according to claim 1, wherein the junction is located at least on the virtual path.   The power storage device according to claim 1, wherein the connection portion is a connection layer existing in all of the uncoated portions constituting the uncoated portion group. 4.   The power storage device according to any one of claims 1 to 3, wherein the welded portion includes the low melting point conductive material. A plurality of electrodes having a metal foil, an active material layer present on at least one surface of the metal foil, and an uncoated portion where the active material layer is not present and the metal foil is exposed are stacked, and An electrode assembly including an uncoated part group in which a coating part is laminated,
A terminal structure for connecting the electrode assembly and an external device,
A welded portion where the uncoated portion group and the terminal structure are welded,
A method for manufacturing a power storage device comprising:
A welding step of welding the uncoated part group and the terminal structure to form the welded part,
Among the uncoated parts constituting the uncoated part group, the uncoated part furthest from the terminal structure is defined as a first uncoated part, and the uncoated part adjacent to the first uncoated part Is the second uncoated part,
A joining step of joining the first uncoated portion and the second uncoated portion by a connecting portion made of a low melting point conductive material to form a joining portion;
Including
The method for manufacturing a power storage device, wherein the joining portion is formed by melting the connecting portion by heat of the welding process.   The method for manufacturing a power storage device according to claim 5, wherein in the welding step, the welding portion is formed so as to include the low-melting-point conductive material. An electrode material manufacturing step of manufacturing an electrode material to be a material of the electrode, and an electrode manufacturing step including a cutting step of cutting the electrode material to form the electrode,
A laminating step of laminating the electrodes produced by the electrode producing step to produce the electrode assembly,
Including
The electrode material manufacturing step includes a first coating step of coating a long strip-shaped metal foil material with an active material mixture to form a first coating portion, and coating a low melting point conductive material on the metal foil material. And a second coating step of forming a second coating portion by processing
In the cutting step, the metal foil is formed by the metal foil material, the active material layer is formed by the first coated portion, and the connection portion is formed in the uncoated portion by the second coated portion. The method for manufacturing a power storage device according to claim 5, wherein