JP5962280B2 - Electrode manufacturing method - Google Patents

Description

The present invention relates to a manufacturing method of an electrode with a welded collector tab group and the conductive member a collection of collector tab.

  A vehicle such as an EV (Electric Vehicle) or a PHV (Plug in Hybrid Vehicle) is equipped with a secondary battery such as a lithium ion battery as a power storage device that stores power supplied to an electric motor serving as a prime mover. This type of secondary battery is disclosed in Patent Document 1, for example. The secondary battery has an electrode assembly in which a negative electrode in which a negative electrode active material is applied to a metal foil and a positive electrode in which a positive electrode active material is applied to a metal foil are insulated and laminated. Each electrode is provided with a current collecting tab (also referred to as “lead”) made of a metal foil. And in a secondary battery, the electrode terminal is electrically joined to the current collection tab, and electricity is taken out outside through the electrode terminal.

Japanese Patent Laid-Open No. 9-120836

  For joining the current collecting tab and the electrode terminal, welding such as resistance welding is used. For example, also in patent document 1, welding is employ | adopted for joining of the metal lead board and positive electrode terminal of an electrode assembly. Resistance welding is a method in which the object to be joined is heated by resistance heat generated by passing a large current through the welded portion, and at the same time a large load is applied to weld the object to be joined.

  By the way, a current collection tab is made into the current collection tab group which collected the current collection tab of the same polarity, and the current collection tab group and an electrode terminal are welded. For this reason, when the contact area between current collecting tabs is small, resistance during welding is large, and accordingly, the amount of heat generated at the welded portion increases. At the time of welding, a large load is applied to the current collecting tab group. Therefore, at the time of welding, the current collecting tab may be greatly deformed simultaneously with the melting of the current collecting tab made of the metal foil, and the current collecting tab may break along with the deformation. When the current collecting tab is broken, the current collecting rate from the electrode assembly is lowered, which may affect the output performance of the battery.

The present invention has been made paying attention to such problems existing in the prior art, and its purpose is to ensure the welding of the current collecting tab and the electrode terminal and to suppress the deterioration of the output performance. It is in providing the manufacturing method of the electrode obtained.

In order to solve the above problems, the invention according to claim 1 is that the electrode assembly housed in the case of the power storage device is different in polarity from the first electrode in which the active material is applied to the metal foil and the first electrode. The two electrodes are insulated and laminated to form a layer, and each electrode is provided with a current collecting tab made of metal foil so as to protrude from one end of the electrode. In the method of manufacturing an electrode for welding a current collecting tab group collecting current collecting tabs and an electrode terminal for taking out electricity from each electrode, the current collecting tab group and a plate-like internal terminal constituting the electrode terminal are provided. At least one of the current collecting tab groups is pressed by pressing from the current collecting tab group side toward the internal terminal side using a pressing member having a diameter larger than that of the tip of the welding electrode rod. Some are thinner than the thickness of the current collecting tab group before pressing A pressing step for forming a recess having a thin portion as a bottom, and the thin tab of the current collecting tab group and the internal terminal corresponding to the thin portion are sandwiched between a pair of welding electrode rods and energized. A welding step for forming a welded portion smaller than the concave portion in the concave portion, the tip of the pressing member is formed in an arc shape, and the curvature thereof is smaller than the tip of the electrode rod for welding. Is the gist.

  A thin part is a site | part which reduced thickness in the current collection tab group. That is, a thin part is a site | part where the adhesiveness of the current collection tab which comprises a current collection tab group is raised. For this reason, by providing the current collector tab group and the electrode terminal weld in the thin part, the resistance decreases when welding the current collector tab and the electrode terminal, for example, the current collector tab may break. Can be suppressed. Therefore, a reduction in output performance of the power storage device can be suppressed by ensuring welding reliability.

Before SL thin section, since it is located at the bottom of the recess which is recessed in the thickness direction of the current collector tab group, can be provided a weld in the recess, it is possible to stabilize the position of the welding portion it can. That is, it is possible to suppress misalignment of the welded portion and to ensure the welding of the current collecting tab and the electrode terminal.
Moreover, since the said welding part is located in the said recessed part and is smaller than the said recessed part, a welding part can be reliably provided in a thin part.

The invention described in 請 Motomeko 2 is the manufacturing method of the electrode according to claim 1, wherein the recess is summarized in that provided in the local of the current collector tab group. According to this, compared with the case where a thin part is provided in the whole current collection tab group, the operation | work required for welding can be simplified. As a result, the efficiency of manufacturing the power storage device can be improved.

According to a third aspect of the present invention, in the electrode manufacturing method according to the first or second aspect , the first electrode is a positive electrode, while the second electrode is a negative electrode, and the thin portion Is provided at least in a positive electrode current collecting tab group in which current collecting tabs of the positive electrode are collected. According to this, the certainty of welding of the current collection tab and electrode terminal in a positive electrode can be aimed at.

The gist of the invention according to claim 4 is the electrode manufacturing method according to any one of claims 1 to 3 , wherein the power storage device is a secondary battery.

  ADVANTAGE OF THE INVENTION According to this invention, the reliability of welding of a current collection tab and an electrode terminal can be aimed at, and the fall of output performance can be suppressed.

The exploded perspective view of a secondary battery. The perspective view which shows the external appearance of a secondary battery. The disassembled perspective view which shows the component of an electrode assembly. (A) is a front view which shows the joining aspect of a current collection tab and an electrode terminal, (b) is the 1-1 sectional view taken on the line of (a). 2-2 sectional drawing of Fig.4 (a). Explanatory drawing explaining the relationship between a load and resistance. The schematic diagram which shows the state before pushing a pressing member into the current collection tab group. (A) is a schematic diagram which shows the state which pushed the press member in the current collection tab group, (b) is a schematic diagram which shows the state which performs resistance welding.

Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS.
As shown in FIGS. 1 and 2, an electrode assembly 12 is accommodated in a case 11 in a secondary battery 10 as a power storage device. The case 11 includes a rectangular parallelepiped main body member 13 and a rectangular flat plate-shaped lid member 14. The lid member 14 closes the insertion port 13 a for inserting the electrode assembly 12 into the main body member 13. Both the main body member 13 and the lid member 14 are made of metal (for example, stainless steel or aluminum). Further, the secondary battery 10 of the present embodiment is a prismatic battery whose appearance is square. Further, the secondary battery 10 of the present embodiment is a lithium ion battery.

  A positive electrode terminal 15 and a negative electrode terminal 16 for taking out electricity from the electrode assembly 12 are electrically connected to the electrode assembly 12. In the present embodiment, as shown in FIG. 1, the positive electrode terminal 15 includes a cylindrical positive electrode external terminal 15 a partially exposed outside the case 11 and a plate-shaped positive electrode internal terminal that is entirely accommodated inside the case 11. 15b. In the present embodiment, the negative electrode terminal 16 includes a cylindrical negative electrode external terminal 16a partially exposed outside the case 11 and a plate-shaped negative electrode that is entirely accommodated inside the case 11, as shown in FIG. And an internal terminal 16b. The positive electrode external terminal 15 a and the negative electrode external terminal 16 a are exposed to the outside of the case 11 through a pair of opening holes 17 arranged in parallel with the lid member 14 at a predetermined interval. Further, a ring-shaped insulating ring 18 for insulating from the case 11 is attached to each of the positive terminal 15 and the negative terminal 16.

  As shown in FIG. 3, the electrode assembly 12 insulates the positive electrode 19 as a sheet-like first electrode, the negative electrode 20 as a sheet-like second electrode, and the positive electrode 19 and the negative electrode 20 from each other. Separator 21. The electrode assembly 12 is configured by alternately laminating separators 21 between a plurality of positive electrodes 19 and a plurality of negative electrodes 20. That is, the electrode assembly 12 is provided with a plurality of sets each including the positive electrode 19, the negative electrode 20, and the separator 21.

  The positive electrode 19 includes a positive electrode metal foil (in this embodiment, an aluminum foil) 22 and a positive electrode active material layer 23 formed by applying a positive electrode active material on both surfaces thereof. A positive electrode current collecting tab 24 made of a positive electrode metal foil 22 is provided so as to protrude from an edge portion 19 a as one end of the positive electrode 19. The positive electrode current collecting tab 24 constitutes an uncoated portion where no positive electrode active material is applied. In addition, the positive electrode current collecting tab 24 is formed in the same position and in the same shape in each positive electrode 19 constituting the electrode assembly 12.

  The negative electrode 20 has a negative electrode metal foil (copper foil in this embodiment) 25 and a negative electrode active material layer 26 formed by applying a negative electrode active material on both surfaces thereof. Further, a negative electrode current collecting tab 27 made of a negative electrode metal foil 25 is provided so as to protrude from an edge portion 20 a as one end of the negative electrode 20. The negative electrode current collecting tab 27 constitutes an uncoated portion where no negative electrode active material is applied. Further, the negative electrode current collecting tab 27 is formed in the same shape at the same position in each negative electrode 20 constituting the electrode assembly 12. Further, the negative electrode current collecting tab 27 is provided at a position where the positive electrode current collecting tab 24 does not overlap with the positive electrode current collecting tab 24 when the positive electrode 19 and the negative electrode 20 are laminated.

  The positive electrodes 19 constituting the electrode assembly 12 are stacked such that the respective positive electrode current collecting tabs 24 are arranged in a row along the stacking direction. Similarly, each negative electrode 20 constituting the electrode assembly 12 is laminated such that the respective negative electrode current collecting tabs 27 are arranged in a row along the laminating direction so as not to overlap the positive electrode current collecting tabs 24. The Then, as shown in FIG. 1, each positive electrode current collecting tab 24 is collected in a range from one end to the other end in the stacking direction of the electrode assembly 12 to form a positive electrode current collecting tab group 28. Similarly, the negative electrode current collecting tabs 27 are gathered in a range from one end to the other end in the stacking direction of the electrode assembly 12 as shown in FIG.

  The positive electrode current collecting tab group 28 is electrically connected to the positive electrode internal terminal 15b. The negative electrode current collecting tab group 29 is electrically connected to the negative electrode internal terminal 16b. The positive electrode current collecting tab group 28 and the positive electrode internal terminal 15b, and the negative electrode current collecting tab group 29 and the negative electrode internal terminal 16b are joined by resistance welding.

  As shown in FIGS. 1, 4A, 4B and 5, the positive electrode current collecting tab group 28 and the positive electrode internal terminal 15b to be joined by resistance welding are provided with a welded portion Y. In this weld Y, a nugget N is generated in which a molten metal is solidified after welding by passing an electric current during welding. The diameter of the nugget N is smaller than the diameter D of the welding electrode rod shown by the two-dot chain line in FIG. Note that the current flow range during welding can be changed depending on the welding conditions. For this reason, the size of the nugget N generated by welding varies depending on welding conditions and the like.

  As shown in FIG. 4B and FIG. 5, the positive current collecting tab group 28 is provided with a thin portion 33 having a thickness β that is smaller than the thickness α of the positive current collecting tab group 28. The thin portion 33 is positioned on the bottom 34a of the recessed portion 34 that is depressed by pressing the positive electrode current collecting tab group 28 in the thickness direction. The welded portion Y is provided in the thin portion 33. As shown in FIG. 4A, the recess 34 is recessed so as to be a circular hole in plan view, and is provided to have a diameter larger than the diameter D of the welding electrode rod. The recess 34 is formed so that the bottom 34a has a gentle arc shape. The positive electrode current collecting tab group 28 is deformed so as to be recessed in the thickness direction by the concave portion 34, so that a thin portion 33 is provided in a portion corresponding to the concave portion 34, and the thin portion 33 is compared with other portions. It has a portion where the thickness is reduced.

  The thin portion 33 is a positive electrode in a portion other than the portion where the concave portion 34 is formed, with the degree of adhesion between the positive electrode metal foils 22 as the positive electrode current collecting tabs 24 collected and overlapped to form the positive electrode current collecting tab group 28. It is thin by raising the adhesion between the metal foils 22. That is, the positive electrode current collection tabs 24 collected to form the positive electrode current collection tab group 28 are crushed by the gap between the positive electrode current collection tabs 24 by pressing, and the stacked thickness of the positive electrode current collection tabs 24 is reduced. The degree of adhesion is increased.

  The positive electrode metal foil 22 used for the positive electrode 19 has a thickness of about 10 μm to 20 μm, for example. Further, when the electrode assembly 12 is configured, several tens of positive electrodes 19 are used, for example, 50 or 60. The number of the positive electrode current collecting tabs 24 corresponding to the thin part 33 is the same as the number of the positive electrode current collecting tabs 24 in other parts. However, as described above, the thin part 33 becomes thinner by increasing the adhesion. ing.

  In the present embodiment, the thin portion 33 and the concave portion 34 having the thin portion 33 are provided locally with respect to the positive electrode current collecting tab group 28. The positive electrode current collecting tab group 28 of the present embodiment is provided with a concave portion 34 at one location, and the positive electrode current collecting tab group 28 and the positive electrode internal terminal 15b are connected by a welded portion Y located in the concave portion 34. Welded. Further, the welded portion Y is smaller than the recessed portion 34.

  In the above description, the welded portion Y where the positive electrode current collecting tab group 28 and the positive electrode internal terminal 15b are welded has been described, but the negative electrode current collecting tab group 29 and the negative electrode internal terminal 16b are also provided with the same welded portion Y. . That is, the welded portion Y that welds the negative electrode current collecting tab group 29 and the negative electrode internal terminal 16 b is located in the recess 34 provided in the negative electrode current collecting tab group 29 and is provided in the thin portion 33. Further, the welded portion Y where the negative electrode internal terminal 16 b is welded is smaller than the recessed portion 34.

  Hereinafter, a method of welding the positive electrode current collecting tab group 28 and the positive electrode internal terminal 15b will be described. In addition, the welding method demonstrated below is the same also when welding the negative electrode current collection tab group 29 and the negative electrode internal terminal 16b. For this reason, regarding the description of the method of welding the negative electrode current collecting tab group 29 and the negative electrode internal terminal 16b, the positive electrode current collecting tab group 28 and the positive electrode internal terminal 15b in the following description are referred to as “negative electrode current collecting tab group 29”. "Negative electrode internal terminal 16b" shall be read respectively.

  The breakage of the current collecting tab during welding is greatly affected by heat generation and pressurization accompanying welding. In particular, if the contact area between the current collecting tabs constituting the current collecting tab group is small, the resistance during welding increases and the amount of heat generated also increases. For this reason, in the site | part with a large emitted-heat amount, the metal foil which comprises a current collection tab progresses easily, and a fracture | rupture etc. are easy to produce with the load added to a current collection tab at the time of welding.

  As shown in FIG. 6, the resistance that can occur during welding becomes smaller as the load is applied, as can be understood from the experiment results of the present applicant. That is, when a load is applied to the current collecting tab group, the contact area between the current collecting tabs constituting the current collecting tab group increases, that is, the degree of adhesion between the current collecting tabs increases. For this reason, in this embodiment, paying attention to the above points, when joining the positive electrode current collecting tab group 28 and the positive electrode internal terminal 15b by resistance welding, the procedure described below can be taken.

  First, as shown in FIG. 7, the positive electrode current collector tab group 28 and the positive electrode internal terminal 15b are overlapped before the positive electrode current collector tab group 28 and the positive electrode internal terminal 15b are subjected to resistance welding. In the group 28, a round bar-shaped pressing member 35 is positioned at a location to be a welding site. The pressing member 35 is a metal or resin rod.

  Then, as shown in FIG. 8A, the positive electrode current collecting tab group 28 is pressed by the pressing member 35. Thereby, in the positive electrode current collecting tab group 28, a concave portion 34 that is recessed in the thickness direction is formed, and a thin portion 33 is formed on the bottom 34 a of the concave portion 34. In this pressing step, the pressing member 35 is pressed so as to give the positive current collecting tab group 28 a load whose resistance approaches approximately zero based on the relationship between the resistance and the load shown in FIG. The load is equal to or greater than the load applied during welding resistance. Further, the thickness β of the thin portion 33 is an amount determined according to a result of applying a load such that the resistance approaches approximately zero.

  And the shape of the pressing member 35 is set so that the recessed part 34 of the magnitude | size which can insert the electrode rod 36 for welding shown in FIG.8 (b) in the subsequent process is formed. That is, the diameter of the pressing member 35 is larger than the diameter of the welding electrode rod 36. The tip of the pressing member 35 is formed in an R shape, and its curvature is set smaller than the tip of the welding electrode rod 36. Since the tip of the pressing member 35 is formed in an R shape, the bottom 34a of the recess 34 is formed in a gentle arc shape.

  This pressing step increases the contact area between the positive electrode current collecting tabs 24 constituting the positive electrode current collecting tab group 28 before resistance welding. In the pressing step, the positive current collecting tab group 28 having a thickness α is pressed to form a thin portion 33 having a thickness β in the positive current collecting tab group 28 at a location to be a welded portion. At this time, the thin portion 33 is in a state of being pressed and hardened by pressing. For this reason, in the positive electrode current collecting tab group 28, resistance at the time of resistance welding is reduced at a portion corresponding to the thin portion 33.

  Then, after the pressing step, as shown in FIG. 8B, the thin electrode 33 tab side of the positive electrode current collecting tab group 28 and the positive electrode internal terminal 15 b side corresponding to the thin portion 33 are paired with a pair of welding electrode rods 36. Insert between and energize. By this welding process, the positive electrode current collecting tab group 28 and the positive electrode internal terminal 15 b are welded at a portion corresponding to the thin portion 33. The thin portion 33 is provided with a welded portion Y. In the welding process, a load is applied to the positive electrode current collecting tab group 28 and the positive electrode internal terminal 15 b by the welding electrode rod 36. For this reason, in the thin part 33, a dent is further formed in the part where the nugget N is generated. Therefore, the positive electrode current collecting tab group 28 after welding is provided with a dent formed by the concave portion 34 and a dent formed by pressing the welding electrode rod 36 on the thin portion 33 located at the bottom 34 a of the concave portion 34. .

Hereinafter, the operation of the present embodiment will be described.
As described above, when the positive electrode current collecting tab group 28 and the positive electrode internal terminal 15b are joined, the pressure member 35 is pressed so as to increase the contact area of the positive electrode current collecting tab 24 before the resistance welding. 33 is formed. Similarly, when the negative electrode current collecting tab group 29 and the negative electrode internal terminal 16b are joined, the pressing member 35 is pressed to increase the contact area of the negative electrode current collecting tab 27 before the resistance welding, so that the thin portion 33 is formed. Forming. Then, after the thin portion 33 is formed, resistance welding is performed on the thin portion 33. For this reason, in the positive electrode current collecting tab group 28, the resistance at the time of welding is reduced due to the increase in the contact area of the positive electrode current collecting tab 24 located in the thin portion 33, and therefore, a local increase or variation in the amount of heat generation occurs. It is suppressed, and the positive electrode current collecting tab 24 is hardly broken. Similarly, in the negative electrode current collecting tab group 29, since the resistance during welding is reduced, the negative electrode current collecting tab 27 is not easily broken.

  As a result, the secondary battery 10 having the electrode assembly 12 in which the positive electrode current collecting tab group 28 and the positive electrode internal terminal 15b are bonded and the negative electrode current collecting tab group 29 and the negative electrode internal terminal 16b are bonded as described above, A decrease in output performance is suppressed. That is, the secondary battery 10 can maintain the assumed output performance.

Therefore, according to the present embodiment, the following effects can be obtained.
(1) A thin portion 33 having a high degree of adhesion between the positive electrode current collecting tab 24 and the negative electrode current collecting tab 27 is provided, and the thin portion 33 is welded. For this reason, since the resistance during welding is reduced in the thin portion 33, a local increase or variation in the amount of generated heat is suppressed, and the positive electrode current collecting tab 24 and the negative electrode current collecting tab 27 are not easily broken. Therefore, the certainty of welding can be achieved and a decrease in output performance in the secondary battery 10 can be suppressed.

(2) By providing the welded part Y in the thin part 33 in the recess 34, the position of the welded part Y can be stabilized. That is, it is possible to suppress the misalignment of the welded portion Y and to ensure the welding reliability.
(3) The thin portion 33 is provided locally in the positive electrode current collecting tab group 28 and the negative electrode current collecting tab group 29. For this reason, compared with the case where the thin part 33 is provided in the whole positive electrode current collection tab group 28 and the negative electrode current collection tab group 29, the operation | work required for welding can be simplified. That is, the manufacturing efficiency of the secondary battery 10 can be improved.

  (4) By providing the thin part 33 in both the positive electrode current collecting tab group 28 and the negative electrode current collecting tab group 29, it is possible to achieve welding reliability in both the positive electrode current collecting tab 24 and the negative electrode current collecting tab 27. Moreover, when the positive electrode metal foil 22 is an aluminum foil and the negative electrode metal foil 25 is a copper foil, the aluminum foil is more easily broken than the copper foil. For this reason, the welding method of the present embodiment, that is, providing the welded portion Y in the thin portion 33 can be suitably employed in welding the positive electrode current collecting tab group 28 and the positive electrode internal terminal 15b.

  (5) The thin portion 33 is formed by pressing the positive electrode current collecting tab group 28 and the negative electrode current collecting tab group 29 with the pressing member 35. For this reason, the adhesion degree of the positive electrode current collection tab 24 and the negative electrode current collection tab 27 can be raised by a simple method.

  (6) Moreover, the shape of the pressing member 35 is set so that the recessed part 34 of the magnitude | size which can insert the electrode rod 36 for welding is formed. That is, the pressing member 35 has a larger diameter than the welding electrode rod 36. For this reason, the welding part Y can be provided in the thin part 33 reliably. Further, when the welding electrode rod 36 is inserted into the recess 34, the positive electrode current collecting tab 24 and the negative electrode current collecting tab 27 around the recess 34 are not crushed by the welding electrode rod 36, so that breakage and the like are ensured. Can be suppressed.

  (7) Since the tip of the pressing member 35 is formed in an arc shape, it is possible to suppress the contact of the pressing member 35 with respect to the positive current collecting tab group 28 and the negative current collecting tab group 29 and to provide the thin portion 33 with certainty. Can do. Further, it is difficult to apply a large load locally from the pressing member 35, and it is possible to prevent the positive electrode current collecting tab 24 and the negative electrode current collecting tab 27 from being broken when the pressing member 35 is pressed.

In addition, you may change the said embodiment as follows.
In the embodiment, welding by the thin portion 33 may be used only for joining the positive electrode current collecting tab group 28 and the positive electrode internal terminal 15b. Conversely, welding by the thin portion 33 may be used only for joining the negative electrode current collecting tab group 29 and the negative electrode internal terminal 16b.

In embodiment, you may provide the thin part 33 in multiple places.
In the embodiment, the whole of the positive electrode current collecting tab group 28 and the negative electrode current collecting tab group 29 may be the thin portion 33. That is, the positive current collecting tab group 28 and the negative current collecting tab group 29 may be pressed and deformed before welding so as to have a thickness β.

  In the embodiment, as long as the diameter of the pressing member 35 is larger than the diameter of the welding electrode rod 36, the diameter ratio can be arbitrarily changed. That is, it is only necessary to form a recess 34 larger than the diameter of the welding electrode rod 36.

In the embodiment, the tip shape of the pressing member 35 may be arbitrarily changed.
In the embodiment, the shape of the recess 34 may be changed.
In the embodiment, the joining of the positive electrode current collecting tab group 28 and the positive electrode internal terminal 15b and the joining of the negative electrode current collecting tab group 29 and the negative electrode internal terminal 16b are performed using another welding method instead of resistance welding. May be. For example, you may join by ultrasonic welding.

In the embodiment, the shapes of the positive electrode 19 and the negative electrode 20 may be changed. For example, it may be formed in a square in front view.
The secondary battery 10 of the embodiment is a lithium ion secondary battery, but is not limited thereto, and may be another secondary battery. In short, any ion may be used as long as ions move between the positive electrode active material layer and the negative electrode active material layer and transfer charge.

(Circle) the secondary battery 10 of embodiment may be mounted in a motor vehicle as a vehicle, and may be mounted in an industrial vehicle. Further, the present invention may be applied to a stationary power storage device.
The present invention is not limited to the laminated secondary battery 10 as in the embodiment, and may be applied to a wound secondary battery in which a belt-like positive electrode and a belt-like negative electrode are wound and laminated in layers. In the wound secondary battery, the positive electrode and the negative electrode are insulated with a separator interposed therebetween. And when applying to a winding type secondary battery, the positive electrode current collection tab 24 and the negative electrode current collection tab 27 should just be formed like embodiment.

  The positive electrode 19 may have a positive electrode active material layer formed by applying an active material on one side. Similarly, the negative electrode 20 may have a negative electrode active material layer formed by applying an active material on one side. In this case, the positive electrode active material layer of the positive electrode 19 and the negative electrode active material layer of the negative electrode 20 are disposed so as to face each other.

Next, a technical idea that can be grasped from the above embodiment and another example will be added below.
(B) The power storage device according to claim 2, wherein the bottom of the recess is formed in an arc shape.
(B) The electrode assembly housed in the case of the power storage device is formed by insulating the first electrode obtained by applying an active material on a metal foil and the second electrode having a polarity different from the first electrode, and laminating them. Each electrode is provided with a current collecting tab made of metal foil so as to protrude from one end of the electrode, and a current collecting tab group of current collecting tabs of the same polarity and each electrode. In the electrode welding method for welding the electrode terminal for taking out electricity, at least a part of the current collecting tab group is provided with a thin portion that is thinner than the thickness of the current collecting tab group before pressing by pressing, Then, the electrode welding method of welding the current collecting tab group of the part corresponding to the thin part and the electrode terminal.

  DESCRIPTION OF SYMBOLS 10 ... Secondary battery, 12 ... Electrode assembly, 15 ... Positive electrode terminal, 15b ... Positive electrode internal terminal, 16 ... Negative electrode terminal, 16b ... Negative electrode internal terminal, 19 ... Positive electrode, 20 ... Negative electrode, 22 ... Positive electrode metal foil, 23 ... Positive electrode active material layer, 24 ... Positive electrode current collecting tab, 25 ... Negative electrode metal foil, 26 ... Negative electrode active material layer, 27 ... Negative electrode current collecting tab, 28 ... Positive electrode current collecting tab group, 29 ... Negative electrode current collecting tab group, 33 ... Thin part, 34 ... Recess, 34a ... Bottom, Y ... Welded part.

Claims (4)

The electrode assembly housed in the case of the power storage device is layered by insulating between the first electrode obtained by applying an active material to metal foil and the second electrode having a polarity different from that of the first electrode, and laminating them. Each electrode is provided with a current collecting tab made of a metal foil so as to protrude from one end of the electrode, and a current collecting tab group of current collecting tabs of the same polarity and the electricity from each electrode. In the method of manufacturing an electrode for welding the electrode terminal to be extracted,
In a state where the current collecting tab group and the plate-like internal terminal constituting the electrode terminal are overlapped, a pressing member having a diameter larger than the tip of the welding electrode rod is used from the current collecting tab group side. By pressing toward the internal terminal side, a press is formed in which at least a portion of the current collecting tab group has a concave portion with a bottom that is thinner than the thickness of the current collecting tab group before pressing. A welding portion smaller than the recess in the recess by energizing the step and the thin terminal of the current collecting tab group and the internal terminal corresponding to the thin portion sandwiched between a pair of welding electrode rods And forming a welding process ,
The tip of the pressing member is formed in an arc shape, and the curvature thereof is a manufacturing method of an electrode smaller than the tip of the welding electrode rod . The method of manufacturing an electrode according to claim 1, wherein the concave portion is provided locally in the current collecting tab group. While the first electrode is a positive electrode, the second electrode is a negative electrode,
The method of manufacturing an electrode according to claim 1 , wherein the thin portion is provided in a positive electrode current collecting tab group in which at least the current collecting tabs of the positive electrode are collected. The said electrical storage apparatus is a secondary battery, The manufacturing method of the electrode as described in any one of Claims 1-3 .