JP6601161B2 - Manufacturing method of welded structure - Google Patents

Description

  The present invention relates to a method for manufacturing a welded structure.

  Patent Document 1 discloses a manufacturing method of a welded structure as follows. Specifically, a welded structure (current collector) in which a metal foil laminated portion (current collector) in which a plurality of metal foil portions made of metal foil are laminated in the lamination direction and a metal plate (current collector) are welded. A manufacturing method of an electrode body with a current collecting plate in which a current collecting plate is welded to an electric part is disclosed. More specifically, first, in the pressurizing step, a metal foil laminate (current collector) and a metal plate (current collector) are laminated in the laminating direction to form a laminate, and this laminate Is sandwiched between a pair of electrode chips in a stacking direction, and a pressure state is applied by applying a constant compressive load to the stack through the pair of electrode chips in the stacking direction. Thereafter, in the energization process, a current of a constant magnitude is passed between the pair of electrode chips in this pressurized state for a certain period of time to weld the metal foil laminated portion and the metal plate.

JP 2014-203659 A

  By the way, in the energization process, when the energization process is started (energization to the laminate is started), the shape of the laminate (metal foil laminate and metal plate) changes due to resistance heat (Joule heat) generated by energization. (Shape change due to softening and melting of the laminate). With the change in the shape of the stacked body, at least one of the pair of electrode chips moves in the pressurizing direction (stacking direction), and the distance between the pair of electrode chips (distance in the stacking direction) decreases. That is, the distance between the electrode tips when the laminated body is pressed in the laminating direction with a constant compressive load in the pressurizing step decreases in the energizing step.

  However, when a large number of welded structures are sequentially manufactured (that is, the energization process is sequentially performed), the state of the electrode tip surface (for example, the oxidized state and the shape of the surface) changes. Moreover, the electrical resistance values of the metal foil laminate and the metal plate are not always constant. For this reason, when a large number of welded structures are manufactured sequentially (that is, the energization process is performed sequentially), the resistance heat (Joule heat) generated in the energization process fluctuates, resulting in a change in the shape of the laminate. (Shape change due to softening and melting of the laminated body) may differ greatly between the laminated bodies. For this reason, when the energization process is sequentially performed, the amount of decrease in the distance between the pair of electrode chips, which decreases with the shape change of the stacked body in the energization process, may fluctuate greatly. In other words, the amount of reduction in the distance between the pair of electrode chips that decreases with the change in the shape of the laminate in the energization process may differ greatly between the energization processes. Thereby, a big variation may arise in the welding strength of a metal foil laminated part and a metal plate.

  This invention is made | formed in view of this present condition, Comprising: It aims at providing the manufacturing method of the welded structure which can reduce the dispersion | variation in the welding strength of a metal foil laminated part and a metal plate.

One aspect of the present invention is a method for producing a welded structure in which a metal foil laminated portion in which a plurality of metal foil portions made of metal foil are laminated in a laminating direction and a metal plate are welded, and the metal foil the the the laminated portion and the metal plate laminated body obtained by laminating the laminating direction, sandwiching the stacking direction by a pair of electrode tips of the resistance welding machine, the constant in the stacking direction with respect to the laminated body through the pair of electrode tips A pressurizing step for applying a compressive load, and an energizing step for welding the metal foil laminate and the metal plate by passing a current between the pair of electrode tips in the pressurizing state. In the energization step, welding is performed so that the amount of decrease in the distance between the pair of electrode tips (decreasing with a change in the shape of the laminate) after the energization step is started is set to a predetermined constant value. the method of manufacturing a structure, the pair of electrodes Is a first electrode tip that moves in the stacking direction and a second electrode tip that does not move, and the resistance welder is connected to the first electrode tip and is stacked together with the first electrode tip. A first stopper that moves in a direction, and a stationary second stopper that is disposed to face the first stopper in the stacking direction. In the pressurizing step, the first stopper Check whether the distance in the stacking direction between the stopper and the second stopper is the constant value, and if not, the distance between the first stopper and the second stopper The distance applied in the stacking direction is adjusted to the constant value, and in the energization step, the first stopper moving in the stacking direction together with the first electrode chip comes into contact with the second stopper and stops. Thus, the movement of the first electrode chip in the stacking direction is stopped, and thereby the distance between the first electrode chip and the second electrode chip after the energization process is started is reduced. It is a manufacturing method of the welded structure which makes quantity the said constant value .

  In the manufacturing method described above, in the pressurizing step, the metal foil laminated portion and the metal plate are laminated (superposed) in the laminating direction, and a pair of electrode chips (metal foil laminated portion is brought into contact with the metal foil. A laminated body (metal foil laminate) is sandwiched in the laminating direction by a first electrode chip that presses against the plate side and a second electrode chip that contacts the metal plate and presses the metal plate toward the metal foil laminate portion side, and passes through the pair of electrode chips. Part and the metal plate) are in a pressurized state (pressure contact state) in which a certain compressive load is applied in the stacking direction. That is, the laminated body (metal foil laminated portion and metal plate) is pressed (pressed) in the lamination direction with a certain compressive load by the pair of electrode chips. Thereafter, in the energization process, a current is passed between the pair of electrode chips in the above-described pressurization state (a state where the laminate is pressed in the laminating direction with a constant compressive load), and the metal foil laminate portion and A metal plate is welded (that is, a laminated body is welded).

  As described above, in the conventional manufacturing method, when a large number of welded structures are sequentially manufactured (that is, the energization process is sequentially performed), the number decreases with a change in the shape of the laminate in the energization process. The amount of decrease in the distance between the pair of electrode tips sometimes fluctuated greatly. In other words, the amount of reduction in the distance between the pair of electrode chips that decreases with the change in the shape of the laminate in the energization process may differ greatly between the energization processes. Thereby, a big variation may arise in the welding strength of a metal foil laminated part and a metal plate.

  On the other hand, in the above-described manufacturing method, in the energization process, the amount of decrease in the distance between the pair of electrode chips (which decreases with the shape change of the laminate) after the energization process is started is set in advance. To a certain value (restricted to a certain value). That is, control is performed so that the amount of decrease in the distance between the pair of electrode chips after the start of the energization step becomes a predetermined constant value. In other words, in the energization process, when the amount of decrease in the distance between the pair of electrode chips after the energization process starts reaches a predetermined constant value, the movement of the pair of electrode chips is stopped ( Fix the position of the pair of electrode tips). Thereby, a metal foil laminated part and a metal plate can be welded stably, and the variation in the welding strength between a metal foil laminated part and a metal plate can be made small.

  In addition, as a metal foil laminated part, what laminated | stacked several metal foil (or one part) in the lamination direction is mentioned. Specifically, for example, the active material layer uncoated portion consisting only of metal foil of the current collector foil (positive electrode current collector foil or negative electrode current collector foil) of the electrode constituting the laminated electrode body of the secondary battery , Which corresponds to the metal foil portion), a plurality of layers laminated in the stacking direction. In this case, as the metal plate, for example, a plate-like current collecting terminal can be mentioned. The laminated electrode body refers to an electrode body in which a plurality of sheet-like positive electrodes and a plurality of sheet-like negative electrodes are laminated with a separator interposed between the positive electrode and the negative electrode.

  Further, the metal foil laminate portion may be a laminate of a plurality of metal foil portions (metal foil portions) in the lamination direction. Specifically, for example, the end of the current collector foil (positive electrode current collector foil or negative electrode current collector foil) of the electrode constituting the flat wound electrode body of the secondary battery (uncoated active material layer made only of metal foil) Among the engineering parts), a plurality of rectangular portions (which correspond to metal foil portions) arranged in the stacking direction (thickness direction of the electrode body) are stacked in the stacking direction. The flat wound electrode body refers to an electrode body in which a belt-like positive electrode and a belt-like negative electrode are wound into a flat shape with a separator interposed between the positive electrode and the negative electrode.

It is sectional drawing of the secondary battery concerning embodiment. It is a perspective view of the electrode body of the battery. It is a figure which shows the positive electrode which comprises the same electrode body. It is a figure which shows the negative electrode which comprises the same electrode body. It is a figure explaining the manufacturing method of the electrode body. It is a flowchart which shows the flow of the manufacturing method of the secondary battery concerning embodiment. It is a front view of the lid member with a terminal concerning an embodiment. It is a figure explaining the manufacturing method of the electrode body with a terminal (welding structure) concerning an embodiment. It is another figure explaining the manufacturing method of the electrode body with a terminal (welding structure) concerning an embodiment. It is another figure explaining the manufacturing method of the electrode body with a terminal (welding structure) concerning an embodiment. It is a front view of an electrode body with a terminal (welding structure) concerning an embodiment. It is a figure which shows the result of a welding test. It is a correlation diagram of the fixed value L1 and tensile strength.

First, the secondary battery 100 according to the present embodiment will be described.
As shown in FIG. 1, the secondary battery 100 is a rectangular sealed lithium ion secondary battery including a rectangular parallelepiped battery case 110, a positive external terminal 121, and a negative external terminal 131. Among these, the battery case 110 is a hard case having a metal rectangular housing part 111 and a metal lid part 112 forming a rectangular parallelepiped housing space. An electrode body 150 and the like are housed inside the battery case 110 (the square housing portion 111).

  The electrode body 150 is a flat wound electrode body in which a belt-like positive electrode 155 and a belt-like negative electrode 156 are wound into a flat shape with a separator 157 interposed between the positive electrode 155 and the negative electrode 156 (see FIG. 2).

  As shown in FIG. 3, the positive electrode 155 has a strip shape extending in the longitudinal direction DA, a positive electrode current collector foil 151 made of an aluminum foil, and a positive electrode active material layer coated on a part of the surface of the positive electrode current collector foil 151 152. The positive electrode active material layer 152 includes a positive electrode active material 153, a conductive material made of acetylene black, and a binder.

  A portion of the positive electrode 155 where the positive electrode active material layer 152 is coated is referred to as a positive electrode active material layer coating portion 155c. On the other hand, a portion where the positive electrode active material layer 152 is not coated (that is, a portion formed of only the positive electrode current collector foil 151) is referred to as a positive electrode active material layer uncoated portion 155b. The positive electrode active material layer uncoated portion 155b is located at the end (left end in FIG. 3) of the positive electrode current collector foil 151 (positive electrode 155) in the width direction DB (left and right direction in FIG. 3), and the positive electrode current collector foil 151 Along the one long side of (positive electrode 155), the positive electrode current collector foil 151 (positive electrode 155) extends in a band shape in the longitudinal direction DA.

  The positive electrode active material layer uncoated portion 155b is wound in a flat shape at one end portion in the width direction DB of the electrode body 150 (the right end portion in FIGS. 1 and 2). The positive electrode active material layer uncoated portion 155b is composed of a plurality of rectangular metal foil portions 155b1, a plurality of arc-shaped upper arc-shaped portions 155b2, and a plurality of arc-shaped lower arc-shaped portions 155b3. (See FIG. 2). The plurality of rectangular metal foil portions 155b1 are arranged in the thickness direction (stacking direction DC) of the electrode body 150 to form a metal foil stacked portion 155d. Therefore, the electrode body 150 has a rectangular metal foil portion 155b1 that is a part of the positive electrode current collector foil 151 at one end portion (right end portion in FIGS. 1 and 2) of the electrode body 150 in the width direction DB. A plurality of metal foil laminated portions 155d are laminated in the lamination direction DC (the thickness direction of the electrode body 150).

  Further, as shown in FIG. 4, the negative electrode 156 includes a negative electrode current collector foil 158 made of a copper foil in a strip shape extending in the longitudinal direction DA, and a negative electrode active material coated on a part of the surface of the negative electrode current collector foil 158 Layer 159. The negative electrode active material layer 159 includes a negative electrode active material 154, SBR (binder), and CMC (thickening agent).

  A portion of the negative electrode 156 where the negative electrode active material layer 159 is coated is referred to as a negative electrode active material layer coating portion 156c. On the other hand, a portion of the negative electrode 156 where the negative electrode active material layer 159 is not coated (that is, a portion formed of only the negative electrode current collector foil 158) is referred to as a negative electrode active material layer uncoated portion 156b. The negative electrode active material layer uncoated portion 156b is a band in the longitudinal direction DA (vertical direction in FIG. 4) of the negative electrode current collector foil 158 (negative electrode 156) along one long side of the negative electrode current collector foil 158 (negative electrode 156). It extends to.

  The negative electrode active material layer uncoated portion 156b is wound in a flat shape at the other end portion in the width direction DB of the electrode body 150 (the left end portion in FIGS. 1 and 2). The negative electrode active material layer uncoated part 156b is composed of a plurality of rectangular metal foil parts 156b1, a plurality of arcuate upper arc parts 156b2, and a plurality of arcuate lower arc parts 156b3. (See FIG. 2). The plurality of rectangular metal foil portions 156b1 are arranged in the thickness direction (stacking direction DC) of the electrode body 150 to form a metal foil stacked portion 156d. Therefore, the electrode body 150 has a rectangular metal foil portion 156b1 that is a part of the negative electrode current collector foil 158 at the other end portion (left end portion in FIGS. 1 and 2) of the electrode body 150 in the width direction DB. A plurality of metal foil laminated portions 156d are laminated in the lamination direction DC (thickness direction of the electrode body 150).

  Further, an aluminum plate-like positive electrode current collecting terminal 122 (metal plate) is joined to the metal foil laminated portion 155d of the positive electrode active material layer uncoated portion 155b by ultrasonic welding. Thereby, the positive electrode active material layer uncoated part 155b (positive electrode 155) is electrically connected to the positive electrode external terminal 121 through the positive electrode current collecting terminal 122 (see FIG. 1).

  A copper plate-like negative electrode current collector terminal 132 (metal plate) is joined to the metal foil laminated portion 156d of the negative electrode active material layer uncoated portion 156b by resistance welding. Thereby, the negative electrode active material layer uncoated part 156b (negative electrode 156) is electrically connected to the negative electrode external terminal 131 through the negative electrode current collection terminal 132 (refer FIG. 1).

  In the present embodiment, the positive external terminal 121 and the positive current collecting terminal 122 are integrally formed to constitute the positive terminal member 120. Further, the negative electrode external terminal 131 and the negative electrode current collecting terminal 132 are integrally formed to constitute the negative electrode terminal member 130.

  The separator 157 is a separator made of a resin film having electrical insulation. The separator 157 is interposed between the positive electrode 155 and the negative electrode 156 to separate them. The separator 157 is impregnated with a non-aqueous electrolyte solution 140 having lithium ions.

Next, the manufacturing method of the welding structure (electrode body with a terminal) and secondary battery concerning this embodiment is demonstrated. FIG. 6 is a flowchart illustrating a flow of a manufacturing method of the welded structure (electrode body with terminal) and the secondary battery according to the embodiment.
As shown in FIG. 6, in step S1, a terminal-attached lid member 160 (see FIG. 7) is produced. Specifically, the lid part 112, the positive electrode terminal member 120, and the negative electrode terminal member 130 are prepared, and these are assembled and integrated. Thereby, the lid member 160 with a terminal which has the cover part 112, the positive electrode terminal member 120, and the negative electrode terminal member 130 as shown in FIG. 7 is obtained.

  In step S2, the electrode body 150 is produced. Specifically, as shown in FIG. 5, the negative electrode 156, the separator 157, the positive electrode 155, and the separator 157 are wound so as to overlap in this order. Specifically, the positive electrode active material layer uncoated portion 155b of the positive electrode 155 and the negative electrode active material layer uncoated portion 156b of the negative electrode 156 are positioned on opposite sides in the width direction DB (left and right direction in FIG. 5). Thus, the negative electrode 156, the separator 157, the positive electrode 155, and the separator 157 are wound into a flat shape to form the electrode body 150 (see FIG. 2).

  The electrode body 150 includes a plurality of metal foil portions 155b1 having a rectangular shape that is a part of the positive electrode current collector foil 151 at one end portion (right end portion in FIGS. 1 and 2) of the electrode body 150 in the width direction DB. The metal foil laminated portion 155d is laminated in the lamination direction DC (thickness direction of the electrode body 150), and at the other end portion (left end portion in FIGS. 1 and 2) of the width direction DB of the electrode body 150, A plurality of metal foil portions 156b1 having a rectangular shape, which is a part of the negative electrode current collector foil 158, have a metal foil laminated portion 156d laminated in the lamination direction DC (thickness direction of the electrode body 150).

Next, a plate-like negative electrode current collector terminal 132 (metal plate) included in the terminal-equipped lid member 160 is attached to the metal foil laminated portion 156d of the negative electrode active material layer uncoated portion 156b of the electrode body 150 by resistance welding. Join.
First, the resistance welder 10 used in this embodiment will be described. As shown in FIG. 8, the resistance welder 10 includes a first electrode tip 30, a second electrode tip 40, a metal foil pressing portion 50, a first stopper bolt 60, and a second stopper bolt 70.

  The first electrode chip 30 and the second electrode chip 40 are a pair of electrode chips, and a metal foil laminated portion 156d and a negative electrode current collecting terminal 132 (metal plate) are laminated in the lamination direction DC between them (overlapping). It is a member for applying a welding current to the laminated body 181 with the laminated body 181 being pressed. The first electrode chip 30 is movable in the stacking direction DC (vertical direction in FIG. 8). On the other hand, the second electrode tip 40 is fixed and does not move. Here, in the stacking direction DC, the direction from the metal foil stacking part 156d toward the negative electrode current collector terminal 132 (downward in FIG. 8) is the first stacking direction DC1, and the opposite direction (upward in FIG. 8) is the second stacking. The direction is DC2.

  In the present embodiment, in the state in which the stacked body 181 is disposed between the first electrode chip 30 and the second electrode chip 40, the first stacking direction DC 1 ( By applying a constant (regular) compressive load F1 (downward in FIG. 8), the laminated body 181 (the metal foil laminated portion 156d and the negative electrode current collecting terminal 132) is formed by the first electrode chip 30 and the second electrode chip 40. It can be in a state of being pressed (pressed) in the stacking direction DC with a constant compressive load F1 (see FIG. 9).

  The metal foil holding part 50 is configured so that a plurality of metal foil parts 156b1 are stacked with a gap in the stacking direction DC and a plurality of metal foil parts 156b1 are stacked in the stacking direction DC without a gap. The member is pressed against the negative electrode current collecting terminal 132 (metal plate) in the stacking direction DC. Accordingly, by pressing the metal foil laminated portion 156d by the metal foil holding portion 50, the plurality of metal foil portions 156b1 are laminated in the stacking direction without any gap between the metal foil holding portion 50 and the negative electrode current collecting terminal 132 (metal plate). A metal foil laminated portion 156d laminated (overlaid) on the DC is disposed. The metal foil pressing portion 50 is movable in the stacking direction DC (vertical direction in FIG. 8). The metal foil pressing part 50 has a cylindrical shape having a through hole 51, and allows the first electrode chip 30 to be inserted into the through hole 51.

  The first stopper bolt 60 and the second stopper bolt 70 are a pair of stoppers. The first stopper bolt 60 is connected to the first electrode chip 30 via a member (not shown) (integrated with the first electrode chip 30), and moves in the stacking direction DC together with the first electrode chip 30. Therefore, when the first electrode chip 30 moves in the stacking direction DC, the first stopper bolt 60 also moves in the stacking direction DC by the same distance. However, the first stopper bolt 60 can be moved in the stacking direction DC independently by driving a servo motor (not shown) (separate from the first electrode chip 30). On the other hand, the second stopper bolt 70 is fixed and does not move. The first stopper bolt 60 and the second stopper bolt 70 are coaxial and are arranged facing the stacking direction DC (see FIG. 8). The 1st stopper volt | bolt 60 is arrange | positioned rather than the 2nd stopper volt | bolt 70 (2nd lamination direction DC2).

Therefore, in the energization process described later, the first stopper bolt 60 moving in the first stacking direction DC1 (downward) together with the first electrode chip 30 is brought into contact with the second stopper bolt 70 and stopped. The movement of the one-electrode chip 30 in the first stacking direction DC1 (downward) can be stopped.
More specifically, in the pressurizing step described later, the laminated body 181 (the metal foil laminated portion 156d and the negative electrode current collecting terminal 132) is fixed at a constant compressive load F1 by the first electrode chip 30 and the second electrode chip 40. If the distance between the first stopper bolt 60 and the second stopper bolt 70 (distance in the stacking direction DC) is set to a constant value L1 in a state of being pressed (pressed) in the stacking direction DC, The amount of movement of the first electrode chip 30 that moves in the first stacking direction DC1 (downward in FIG. 8) in accordance with the shape change of the stacked body 181 after the start of the process (the shape change due to softening and melting of the stacked body 181). The constant value L1 can be set.

  That is, the amount of decrease in the distance between the pair of electrode chips (distance between the first electrode chip 30 and the second electrode chip 40) after the energization process is started can be set to a predetermined constant value L1. it can. In other words, in the energization process, when the amount of decrease in the distance between the first electrode tip 30 and the second electrode tip 40 reaches a certain value L1, the movement of the first electrode tip 30 is stopped, Thereafter, the distance between the first electrode chip 30 and the second electrode chip 40 can be made constant. Thereby, the metal foil laminated part 156d and the negative electrode current collecting terminal 132 can be stably welded, and the variation in the welding strength between the metal foil laminated part 156d and the negative electrode current collecting terminal 132 can be reduced.

  Subsequently, a method of joining the plate-like negative electrode current collector terminal 132 (metal plate) to the metal foil laminated portion 156d of the negative electrode active material layer uncoated portion 156b of the electrode body 150 by resistance welding will be described. As shown in FIG. 8, between the first electrode chip 30 and the second electrode chip 40, the metal foil laminated portion 156d and the negative electrode current collector terminal 132 (metal plate) were laminated in the lamination direction DC (overlapped). ) With the laminated body 181 disposed, the metal foil laminated portion 156d is pressed in the first lamination direction DC1 (downward) by the metal foil pressing portion 50. Thereby, between the metal foil holding | maintenance part 50 and the negative electrode current collection terminal 132 (metal plate), the several metal foil part 156b1 was laminated | stacked on the lamination direction DC without the gap | interval, and the metal foil laminated | stacked part 156d was laminated | stacked. Be placed. At this time, the lower surface of the negative electrode current collecting terminal 132 is in contact with the second electrode chip 40.

  Next, the process proceeds to step S3 (pressurizing step), and the first electrode chip 30 and the second electrode are sandwiched between the first electrode chip 30 and the second electrode chip 40 (a pair of electrode chips) in the stacking direction DC. A pressure state in which a constant (specified value) compressive load F1 is applied to the stacked body 181 in the stacking direction DC through the chip 40 is set. Specifically, as shown in FIG. 9, the first electrode chip 30 is moved in the first stacking direction DC <b> 1 (downward) and is inserted through the through hole 51 of the metal foil pressing portion 50. Then, the first electrode chip 30 applies a constant compressive load F1 to the metal foil laminated portion 156d in the first lamination direction DC1 (downward in FIG. 9). Thereby, the laminated body 181 (the metal foil laminated portion 156d and the negative electrode current collecting terminal 132) was pressed (pressed) in the laminating direction DC with a constant compression load F1 by the first electrode chip 30 and the second electrode chip 40. State.

  In this state, it is confirmed whether or not the distance in the stacking direction DC between the first stopper bolt 60 and the second stopper bolt 70 is a constant value L1. If it is not the constant value L1, the first stopper bolt 60 is moved in the stacking direction DC by driving a servo motor (not shown), and the separation between the first stopper bolt 60 and the second stopper bolt 70 in the stacking direction DC is performed. The distance is adjusted to a constant value L1. In the present embodiment, the constant value L1 = 0.5 mm.

  Next, the process proceeds to step S4 (energization step), and the first electrode chip 30 and the second electrode chip 40 are pressed with the first electrode chip 30 and the second electrode chip 40 in the stacking direction DC with the compression load F1. A certain amount of current is passed between the two-electrode chip 40 for a certain time (for example, 20 ms), and the metal foil laminated portion 156d and the negative electrode current collector terminal 132 (laminated body 181) are resistance-welded (FIG. 10). reference).

  By the way, in the energization process, when the energization process is started (the energization to the laminated body 181 is started), the laminated body 181 (the metal foil laminated portion 156d and the negative electrode current collector) is generated by resistance heat (Joule heat) generated by the energization. The terminal 132) is deformed (softened and melted). With the deformation of the stacked body 181, the first electrode chip 30 moves in the first stacking direction DC1 (downward), and the distance between the first electrode chip 30 and the second electrode chip 40 (stacking direction DC ) Will decrease.

  However, when a large number of welded structures (electrode bodies with terminals) are sequentially manufactured (that is, the energization process is sequentially performed), the surface states of the first electrode tip 30 and the second electrode tip 40 (for example, Oxidation state, surface shape) changes. Further, the electric resistance values of the metal foil laminated portion 156d and the negative electrode current collecting terminal 132 are not always constant. For this reason, when a large number of welded structures (electrode bodies with terminals) are sequentially manufactured (that is, the energization process is performed sequentially), the resistance heat (Joule heat) generated in the energization process fluctuates. The accompanying change in the shape of the stacked body 181 may be greatly different among the multiple stacked bodies 181.

  For this reason, in the conventional manufacturing method (for example, patent document 1), if an energization process is performed sequentially, it will be between the 1st electrode chip and 2nd electrode chip which reduce with the shape change of the laminated body in an energization process. The amount of decrease in the distance sometimes fluctuated greatly. In other words, the amount of reduction in the distance between the pair of electrode chips that decreases with the change in the shape of the stacked body in the energization process may vary greatly between the plurality of energization processes. Thereby, a big variation may arise in the welding strength of a metal foil laminated part and a metal plate.

  In contrast, in the present embodiment, as shown in FIG. 10, the first stopper bolt 60 that moves together with the first electrode chip 30 in the first stacking direction DC1 (downward) is brought into contact with the second stopper bolt 70. Thus, the movement of the first electrode chip 30 in the first stacking direction DC1 (downward) is stopped. More specifically, in the previous pressurizing step (step S3), the first electrode chip 30 and the second electrode chip 40 are used to press the stacked body 181 in the stacking direction DC with the compressive load F1. The distance between the 1 stopper bolt 60 and the second stopper bolt 70 (distance in the stacking direction DC) is set to a constant value L1.

  Thus, the first electrode chip 30 that moves in the first stacking direction DC1 (downward in FIGS. 8 to 10) with the shape change of the stacked body 181 (softening and melting of the stacked body 181) after starting the energization process. Can be set to a constant value L1. In FIG. 10, in the previous pressurizing step (step S <b> 3), the first electrode chip 30 and the second electrode chip 40 in the state where the stacked body 181 is pressed in the stacking direction DC with the compression load F <b> 1. The electrode tip 30 and the first stopper bolt 60 are indicated by a two-dot chain line.

  In other words, in the energization process, when the amount of decrease in the distance between the first electrode tip 30 and the second electrode tip 40 reaches a certain value L1, the movement of the first electrode tip 30 is stopped, Thereafter, the distance between the first electrode chip 30 and the second electrode chip 40 can be made constant. The state at this time is shown in FIG. As a result, even when the plurality of laminated bodies 181 are sequentially welded (the energization process is sequentially repeated), the metal foil laminated portion 156d and the negative electrode current collecting terminal 132 can be stably welded, and the metal foil laminated Variation in welding strength between the portion 156d and the negative electrode current collecting terminal 132 can be reduced. This is clear from the result of the welding test described later.

  In the energization process, the magnitude of the current value passed between the first electrode tip 30 and the second electrode tip 40 and the energization time are determined by “assuming that the first stopper bolt 60 and the second stopper bolt 70 are used. If the movement of the first electrode tip 30 is not limited, the amount of decrease in the distance between the first electrode tip 30 and the second electrode tip 40 due to energization is set to a value that is equal to or greater than a certain value L1. .

  Further, in the energization process, when the amount of decrease in the distance between the first electrode tip 30 and the second electrode tip 40 reaches a certain value L1, the movement of the first electrode tip 30 is stopped, and thereafter By making the distance between the first electrode chip 30 and the second electrode chip 40 constant, it is possible to suppress an excessive load from being applied to the first electrode chip 30 and the second electrode chip 40. Thereby, progress of deterioration of the 1st electrode tip 30 and the 2nd electrode tip 40 can be delayed, and the life of the 1st electrode tip 30 and the 2nd electrode tip 40 can be lengthened.

  Next, the plate-like positive electrode current collecting terminal 122 included in the terminal-attached lid member 160 is joined to the metal foil laminated portion 155d of the positive electrode active material layer uncoated portion 155b of the electrode body 150 by ultrasonic welding. Specifically, the metal foil laminated portion 155d and the positive electrode current collector terminal 122 are sandwiched and pressed by an ultrasonic anvil and an ultrasonic horn (not shown). In this state, the ultrasonic horn is vibrated ultrasonically to join the positive electrode current collecting terminal 122 to the metal foil laminated portion 155d.

  Accordingly, as shown in FIG. 11, the positive electrode terminal member 120 and the positive electrode 155 are electrically connected, the negative electrode terminal member 130 and the negative electrode 156 are electrically connected, and the lid member 160 with a terminal A terminal-attached electrode body 170 (welded structure) integrated with the electrode body 150 is completed. The terminal-attached electrode body 170 is a welded structure in which the terminal-attached lid member 160 and the electrode body 150 are welded, and the metal foil laminated portion 156d of the electrode body 150 and the negative electrode current collecting terminal 132 of the terminal-attached lid member 160. (Metal plate) is a welded structure joined by resistance welding.

  Thereafter, the process proceeds to step S5, in which the electrode body 150 of the electrode body with terminal 170 (welded structure) is housed in the square housing portion 111 and the opening of the square housing portion 111 is closed by the lid portion 112. Next, the lid portion 112 and the square housing portion 111 are welded. A liquid injection hole 112b penetrating the lid 112 is formed in the center of the lid 112 (see FIG. 1).

  Next, the process proceeds to step S <b> 6, the nonaqueous electrolyte solution 140 is injected into the battery case 110 through the liquid injection hole 112 b of the battery case 110, and the electrode body 150 is impregnated with the nonaqueous electrolyte solution 140. Thereafter, the injection hole 112b is sealed with the injection lid 114, whereby the secondary battery 100 of the present embodiment is completed (see FIG. 1).

(Welding test)
Next, a plurality (specifically, 3000) of electrode bodies 150 and negative electrode terminal members 130 are prepared, and step S3 (pressure process) and step are sequentially performed using the above-described resistance welding machine 10. S4 (energization process) was performed, and resistance welding of the metal foil lamination | stacking part 156d of the electrode body 150 and the negative electrode current collection terminal 132 (lamination body 181) of the negative electrode terminal member 130 was carried out (refer FIGS. 8-10). However, in this test, 3000 samples are welded with the same first electrode tip 30 and second electrode tip 40 without exchanging the first electrode tip 30 and the second electrode tip 40.

  In this test, the constant value L1 is set to 0.5 mm in any resistance welding. That is, in the pressurizing process of 3000 times, the first electrode chip 30 and the second electrode chip 40 are used to cause the laminate 181 (the metal foil laminate 156d and the negative electrode current collector terminal 132) to be laminated in the stacking direction DC with a constant compressive load F1. In the state where the pressure is pressed (pressure contact), the separation distance in the stacking direction DC between the first stopper bolt 60 and the second stopper bolt 70 is unified to a constant value L1 = 0.5 mm. Thereby, in the energization process 3000 times, the movement amount of the first electrode chip 30 that moves in the first stacking direction DC1 (downward in FIGS. 8 to 10) with the shape change (softening and melting) of the stacked body 181 is reduced. The constant value L1 = 0.5 mm.

  Thereafter, as described above, for the 3000 samples in which the negative electrode current collector terminal 132 of the negative electrode terminal member 130 was resistance-welded to the metal foil laminate portion 156d of the electrode body 150, the metal foil laminate portion 156d, the negative electrode current collector terminal 132, In order to grasp the welding strength, a tensile strength test was conducted. Specifically, each sample is set in a known tensile strength tester, and the negative electrode current collector terminal 132 is separated from the metal foil laminated portion 156d (negative electrode active material layer uncoated portion 156b) (first lamination direction) DC1) and the maximum value (N) of the tensile stress until the negative electrode current collector terminal 132 was peeled off from the metal foil laminated portion 156d (negative electrode active material layer uncoated portion 156b) was measured. The test results are shown in FIG. In FIG. 12, the maximum value of tensile stress is shown as tensile strength (N).

  As shown in FIG. 12, all of the 3000 samples had a tensile strength in the range of 220 to 240N. As a result, according to the manufacturing method of the present embodiment, the metal foil laminated portion 156d and the negative electrode current collector terminal 132 (metal plate) can be stably welded, and the metal foil laminated portion 156d and the negative electrode current collector terminal can be welded. It can be said that the variation in the welding strength between 132 can be reduced. That is, in the energization process, the amount of movement of the first electrode tip 30 that moves in the first stacking direction DC1 (downward in FIGS. 8 to 10) with the shape change (softening and melting) of the stacked body 181 is a constant value L1. By doing so, it can be said that the variation in the welding strength between the metal foil laminated portion 156d and the negative electrode current collecting terminal 132 (metal plate) can be reduced.

(Preferable range of constant value L1)
Next, a preferable range of the constant value L1 was investigated. Specifically, a plurality of samples are prepared, and the value of the constant value L1 is varied within the range of 0.2 mm to 1.2 mm, and in the same manner as in the embodiment, for each sample, the metal foil laminated portion 156d and The negative electrode current collector terminal 132 was resistance welded. Then, in order to grasp | ascertain the welding strength of the metal foil laminated part 156d and the negative electrode current collection terminal 132 about these samples similarly to the above-mentioned welding test, the tensile strength test was done. The result is shown in FIG.

  As shown in FIG. 13, the welding strength between the metal foil laminated portion 156d and the negative electrode current collector terminal 132 could be increased by welding with the constant value L1 being 0.4 mm or more. However, when welding was performed with the constant value L1 greater than 0.7 mm, the deformation of the negative electrode current collector terminal 132 (metal plate) increased. It is preferable that the welding strength (tensile strength) is high, and the deformation of the negative electrode current collector terminal 132 (metal plate) is preferably small. Therefore, it can be said that the value of the constant value L1 is preferably 0.4 mm or more and 0.7 mm or less.

  In the above, the present invention has been described with reference to the embodiments. However, the present invention is not limited to the above embodiments, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof.

  For example, in the embodiment, among the end portions of the negative electrode current collector foil (the negative electrode active material layer uncoated portion 156b) constituting the flat wound electrode body 150 as the metal foil laminated portion, rectangular shapes aligned in the lamination direction DC are arranged. The shape part (this is corresponded to a metal foil part) illustrated what was laminated | stacked by two or more in the lamination direction DC. However, the metal foil laminate is not limited to this. For example, the metal foil laminated part is an end part of the current collector foil (positive electrode current collector foil or negative electrode current collector foil) of the electrode constituting the laminated electrode body (the active material layer non-coated part consisting only of the metal foil, which is a metal (Corresponding to a foil portion) may be laminated in the laminating direction.

In addition, the metal foil laminated portion is not limited to a part of the electrode body, and may be any one as long as “a plurality of metal foil portions made of metal foil are laminated in the laminating direction”. Also good.
In the embodiment, the current collecting terminal (negative current collecting terminal 132) is exemplified as the metal plate, but the metal plate is not limited to this. The metal plate may be any plate-shaped metal member.

DESCRIPTION OF SYMBOLS 10 Resistance welding machine 30 1st electrode tip 40 2nd electrode tip 60 1st stopper bolt 70 2nd stopper bolt 100 Secondary battery 130 Negative electrode terminal member 132 Negative electrode current collection terminal (metal plate)
156b Negative electrode active material layer uncoated portion 156b1 Metal foil portion 156c Negative electrode active material layer coated portion 156d Metal foil laminated portion 158 Negative electrode current collector foil (metal foil)
159 Negative electrode active material layer 110 Battery case 112 Lid 150 Electrode body 155 Positive electrode 156 Negative electrode 157 Separator 160 Lid member with terminal 170 Electrode body with terminal (welded structure)
181 Laminated body DB Width direction DC Laminating direction L1 Constant value S3 Pressurizing step S4 Energizing step

Claims (1)

A metal foil laminated portion in which a plurality of metal foil portions made of metal foil are laminated in a laminating direction, and a method for producing a welded structure in which a metal plate is welded,
A laminated body obtained by laminating the metal foil laminated portion and the metal plate in the laminating direction is sandwiched in the laminating direction by a pair of electrode chips of a resistance welder, and the laminating direction with respect to the laminated body through the pair of electrode chips A pressurizing step for applying a certain compression load to the pressurizing state;
An electric current process in which a current is passed between the pair of electrode chips in the pressurized state to weld the metal foil laminate and the metal plate,
In the energization process, in the method for manufacturing a welded structure, the amount of decrease in the distance between the pair of electrode tips after the energization process is started is set to a predetermined constant value .
The pair of electrode tips are a first electrode tip that moves in the stacking direction and a stationary second electrode tip,
The resistance welder is connected to the first electrode tip and moves in the stacking direction together with the first electrode tip, and the stationary welder is disposed facing the first stopper in the stacking direction. A second stopper,
In the pressurizing step, in the pressurized state, it is confirmed whether the distance applied in the stacking direction between the first stopper and the second stopper is the constant value, and is not the constant value Adjusts the distance in the stacking direction between the first stopper and the second stopper to the constant value,
In the energization step, the first electrode chip moving in the laminating direction together with the first electrode chip is brought into contact with the second stopper and stopped, thereby moving the first electrode chip in the laminating direction. By stopping, the amount of decrease in the distance between the first electrode chip and the second electrode chip after starting the energization step is set to the constant value.
Method for producing a welded structure.

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