JP6904206B2 - Laser welding equipment - Google Patents

Description

The present invention relates to a laser welding apparatus for laser welding a conductive member and an uncoated portion group.

Conventionally, vehicles such as EVs (Electric Vehicles) and PHVs (Plug in Hybrid Vehicles) are equipped with lithium ion secondary batteries and the like as storage devices for storing power supplied to electric vehicles and the like. The secondary battery includes an electrode assembly in which sheet-shaped positive electrode and negative electrode electrodes are laminated in an insulated state, and a case for accommodating the electrode assembly. The case has a case body containing the electrode assembly and a lid containing an opening of the case body. The electrodes of the positive electrode and the negative electrode have a metal foil, an active material layer existing on both sides or one side of the metal foil, and an uncoated portion in which the active material layer does not exist and the metal foil is exposed. The uncoated portion is, for example, a tab protruding from a part of one side of the metal leaf.

The electrode assembly includes a group of tabs as an uncoated part group in which tabs of each polarity are laminated. The power is taken out from the secondary battery through the electrode terminals connected to the tab group via the conductive member. The tab group and the conductive member are electrically connected by a welded portion formed by laser welding.

By the way, when laser welding a tab group and a conductive member, spatter (metal dust) is generated from the molten tab or the conductive member and adheres to the electrode assembly, the conductive member, and the lid around the welded portion. is there. If the secondary battery is manufactured with the spatter still adhering to the periphery of the weld, the spatter becomes a foreign substance in the secondary battery. Since foreign matter can cause an internal short circuit of a secondary battery, for example, it is desired to suppress the scattering of spatter and prevent the spatter from adhering to the periphery of the welded portion.

Examples of the laser welding apparatus that suppresses spatter scattering include the welding apparatus disclosed in Patent Document 1. The welding apparatus of Patent Document 1 includes a welding chamber in which a welding target portion (tab group) is housed, a welding processing portion for welding the welding target portion inside the welding chamber, and an intake portion for sucking air from the inside of the welding chamber. To be equipped. Then, when welding is performed on the electrode plate, the welding target portion is welded inside the welding chamber, and the intake portion takes in air from the inside of the welding chamber. Therefore, the solid particles (sputter) when the electrode plate is welded can be recovered, and the scattering of the solid particles is suppressed.

Japanese Unexamined Patent Publication No. 2012-204304

By the way, in the welding apparatus disclosed in Patent Document 1, if the welding processing portion is configured to be welded by the laser welding method, the laser irradiation apparatus is arranged outside the welding chamber, and the laser beam emitted from the laser irradiation apparatus is emitted. It is conceivable that the portion to be welded is welded inside the welding chamber while being introduced into the welding chamber. However, holes for introducing the laser beam into the welding chamber are formed in the welding chamber, and the intake force by the intake portion is reduced due to the holes. When the intake force is reduced, the generated solid particles cannot be recovered from the inside of the welding chamber, and spatter adheres to the periphery of the welded portion.

An object of the present invention is to provide a laser welding apparatus capable of suppressing spatter from adhering to the periphery of a welded portion.

A laser welding apparatus for solving the above problems has a positive electrode and a negative electrode having an active material layer on at least one side of the metal foil, and having an uncoated portion where the active material layer does not exist and the metal foil is exposed. An electrode assembly having a structure in which the electrodes of No. 1 are laminated in an insulated state and having an uncoated portion group in which the uncoated portions are laminated with the same polarity on one end face, and the uncoated portion. A laser welding device for forming a welded portion by laser welding the conductive member and the uncoated portion group in a power storage device including a conductive member joined to the portion group, wherein the welded portion is In a state where the conductive member is arranged outside the uncoated portion at one end in the stacking direction of the uncoated portion group, laser light is irradiated from the outside of the uncoated portion at the other end in the stacking direction of the uncoated portion group. A hollow box-shaped spatter cover is provided inside, which is arranged outside the uncoated portion at the other end in the stacking direction of the uncoated portion group, and allows air and the laser beam to pass through. A bottom plate having an air flow path extending from the boundary side between the active material layer and the uncoated portion to the tip end side of the uncoated portion, and covering the uncoated portion at the other end in the stacking direction. The top plate facing the bottom plate has an incident hole for the laser beam penetrating the top plate, and the spatter cover has the incident hole, An air supply mechanism through which the laser beam passes in the order of the flow path and the exit hole and communicates with one end of the flow path of the spatter cover is provided, and the air supply mechanism includes the active material layer and the uncoated material layer. An intake mechanism that is arranged closer to the tip of the uncoated portion than the boundary with the portion and between the end face of the electrode assembly and the spatter cover and communicates with the other end of the flow path of the spatter cover. The gist is to prepare.

According to this, when the air supply mechanism of the laser welding device is driven to supply air to the flow path of the sputtering cover and the air is sucked by the intake mechanism, an air flow is formed in the flow path of the sputtering cover. To. In this state, the laser beam passes through the incident hole, the flow path and the exit hole of the sputter cover, is irradiated to the uncoated portion group, and laser welding is performed.

In the uncoated portion at the other end in the stacking direction, the periphery of the laser-welded portion is covered from the outside by the bottom plate of the spatter cover, so that spatter adheres to the periphery of the laser-welded portion in the uncoated portion. Is suppressed. Further, since the spatter immediately after the generation enters the emission hole surrounding the laser-welded portion, most of the spatter adheres to the wall surface partitioning the emission hole. Further, even if some of the spatter does not adhere to the wall surface of the exit hole and enters the flow path, the air forcibly supplied to the flow path keeps it away from the laser welded part, and further, the intake mechanism. Is sucked into. Therefore, it is possible to prevent spatter from adhering to the periphery of the laser-welded portion, and it is possible to suppress spatter from adhering to the periphery of the welded portion.

Further, in the laser welding apparatus, among the wall surfaces for partitioning the exit holes of the spatter cover, the edge of the wall surface closest to one end of the flow path, which faces the flow path, communicates with one end of the flow path. It is preferably located higher than the bottom edge of the opening of the air supply mechanism.

According to this, by raising the wall surface of the emission hole of the laser light, it is easy to attach the spatter toward the air supply mechanism to the wall surface, and it is easy to suppress the spatter from entering the air supply mechanism.

According to the present invention, it is possible to prevent spatter from adhering to the periphery of the welded portion.

The exploded perspective view which shows the secondary battery of an embodiment. A partial side sectional view showing a secondary battery of an embodiment. (A) is a cross-sectional view showing a welded portion in a state where the tab group is extended, and (b) is a plan view showing a welded portion in a state where the tab group is extended. An exploded perspective view showing a part of a laser welding apparatus. Side sectional view showing a laser welding apparatus. The plan view which shows the laser welding apparatus.

Hereinafter, an embodiment in which the laser welding apparatus is embodied will be described with reference to FIGS. 1 to 6.
As shown in FIG. 1 or 2, the secondary battery 10 as a power storage device includes a case 11. The secondary battery 10 includes an electrode assembly 12 housed in a case 11 and an electrolytic solution (not shown). The case 11 has a rectangular parallelepiped case body 13 and a rectangular flat plate-shaped lid 14 that closes the opening 13a 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). Further, the secondary battery 10 of the present embodiment is a square battery having a square appearance. Further, the secondary battery 10 of the present embodiment is a lithium ion battery.

The secondary battery 10 includes a pair of electrode terminals 15 for extracting electricity from the electrode assembly 12. Of the pair of electrode terminals 15, one electrode terminal 15 is a positive electrode terminal, and the other electrode terminal 15 is a negative electrode terminal. Each electrode terminal 15 penetrates the hole 14a of the lid 14 and projects to the outside of the case 11. A ring-shaped insulating ring 16 for insulating the lid 14 is attached to each electrode terminal 15. Each electrode terminal 15 has a rectangular plate-shaped conductive member 17 in the case 11. Each electrode terminal 15 is electrically connected to the conductive member 17.

As shown in FIG. 2, the electrode assembly 12 includes a positive electrode 21 as a plurality of sheet-shaped positive electrodes and a negative electrode 22 as a plurality of sheet-shaped negative electrodes. The electrode assembly 12 has a layered structure in which a separator 23 is interposed between the positive electrode 21 and the negative electrode 22 to insulate them, and the electrodes are alternately laminated.

The positive electrode 21 and the negative electrode 22 include a rectangular sheet-shaped metal foil 24. The metal foil 24 of the positive electrode 21 is, for example, an aluminum foil, and the metal foil 24 of the negative electrode 22 is, for example, a copper foil. The positive electrode 21 and the negative electrode 22 include an active material layer 25 existing on both sides of the metal foil 24. The active material layer 25 contains an active material, a conductive material, and a binder depending on the polarity. The positive electrode 21 and the negative electrode 22 include a rectangular tab 26 protruding from a part of one of the edges along the pair of long sides. In this embodiment, the longitudinal direction of the tab 26 coincides with the protruding direction of the tab 26 from the edge. The tab 26 is an uncoated portion where the active material layer 25 does not exist and the metal foil 24 is exposed.

In the electrode assembly 12, the tabs 26 of each positive electrode 21 are collected and laminated at one end in the direction in which the positive electrode 21, the negative electrode 22, and the separator 23 are laminated, and the tab group 18 as an uncoated portion group is laminated. To be equipped. Similarly, the electrode assembly 12 is provided as an uncoated portion group in which the tabs 26 of each negative electrode 22 are laminated at one end in the direction in which the positive electrode 21, the negative electrode 22, and the separator 23 are laminated. A tab group 18 is provided. The direction in which the tabs 26 are laminated is defined as the stacking direction. Each tab group 18 exists on the end face 12a facing the lid 14 in the electrode assembly 12. As shown in FIGS. 1 and 2, the electrode assembly 12 is housed in the case 11 in a state where the base end portion and the tip end portion of the tab group 18 in the protruding direction of the tab 26 are bent. The conductive member 17 is located between one end surface of the tab group 18 in the stacking direction and the inner surface of the lid 14. In addition, in FIG. 3 and later, for convenience of explanation, the tab group 18 is shown in a stretched state without being bent.

As shown in FIG. 3A or FIG. 3B, the secondary battery 10 includes a welded portion 31. The welded portion 31 is formed by laser welding all the tabs 26 in the stacking direction. When the stacking direction of the tab group 18 is the vertical direction, one end of the tab group 18 in the stacking direction is the lower end, and the other end of the stacking direction is the upper end, the tab group 18 is viewed from the other end side (upper side) of the stacking direction. At this time, the welded portion 31 has a strip shape extending linearly.

Next, the laser welding apparatus 30 for forming the welded portion 31 will be described.
As shown in FIG. 4 or 5, the laser welding apparatus 30 has a spatter cover 40 arranged outside the tab 26 at the other end in the stacking direction of the tab group 18 and an air supply mechanism 50 communicating with one end of the spatter cover 40. And an intake mechanism 70 communicating with the other end of the spatter cover 40.

The sputter cover 40 is made of ceramics or a metal having a low thermal conductivity. The spatter cover 40 has a hollow box shape. The spatter cover 40 includes a rectangular plate-shaped bottom plate 41. Further, the sputter cover 40 includes a long side wall 42 erected from a long side edge which is a pair of side edges of the bottom plate 41, a first short side wall 43 erected from one short side edge of the bottom plate 41, and a bottom plate. It has a second short side wall 44 erected from the other short side edge of 41. Further, the sputtering cover 40 includes a top plate 45 facing the bottom plate 41 and supported by a pair of long side walls 42, a first short side wall 43, and a second short side wall 44.

The sputter cover 40 includes a bottom plate 41 having a laser beam emitting hole 41a penetrating the bottom plate 41, and a top plate 45 having a laser light incident hole 45a penetrating the top plate 45. The exit hole 41a and the incident hole 45a each have a long hole shape in a plan view. The exit holes 41a are partitioned by the first to third wall surfaces H1 to H3. The wall surface closest to the first short side wall 43 and parallel to the first short side wall 43 is referred to as the first wall surface H1, and the wall surface facing the first wall surface H1 is referred to as the second wall surface H2. The arc-shaped wall surface connecting one ends or the other ends of the first wall surface H1 and the second wall surface H2 is referred to as a third wall surface H3. Of the edge edges of the first to third wall surfaces H1 to H3, one end edge (lower end edge) located on the outer surface (lower surface) of the bottom plate 41 has the same height on the outer surface of the bottom plate 41. On the other hand, of the end edges of the first wall surface H1, the other end edge Ha (upper end edge) facing the flow path 46 in the sputter cover 40 is the opposite side of the one end edge of the second wall surface H2. And at a position higher than the other end edge facing the flow path 46.

The spatter cover 40 includes a flow path 46 extending in the longitudinal direction of the bottom plate 41, and the flow path 46 penetrates the spatter cover 40 along the longitudinal direction of the bottom plate 41. In the sputtering cover 40, the direction through which the flow path 46 penetrates is the axial direction. The sputter cover 40 has a first opening 43a that penetrates the first short side wall 43 in the thickness direction, and has a second opening 44a that penetrates the second short side wall 44 in the thickness direction. Therefore, the sputter cover 40 has a first opening 43a at one end in the axial direction and a second opening 44a at the other end in the axial direction. The flow path 46 communicates with the first opening 43a and the second opening 44a, air flows into the flow path 46 inside the sputtering cover 40 from the first opening 43a, and the air flowing through the flow path 46 is the second. It flows out of the spatter cover 40 through the opening 44a. Therefore, the flow path 46 allows air to pass through the inside of the sputtering cover 40.

Of the end edges of the first opening 43a, one end edge 43c (lower end edge) on the bottom plate 41 side is located at a position lower than one end edge (lower end edge) on the bottom plate 41 side of the end edges of the second opening 44a. Further, of the end edges of the first opening 43a, the other end edge (upper end edge) which is the opposite side of the one end edge 43c is the other end edge (upper end edge) which is the opposite side of the end edge of the second opening 44a. ) It is in a lower position. Therefore, the first opening 43a is located at a position deviated from the second opening 44a, and specifically, the first opening 43a is located at a position lower than the second opening 44a.

Further, the bottom plate 41 becomes thicker from the first opening 43a toward the first wall surface H1, and the surface (upper surface) of the portion where the thickness becomes thicker is provided with the first inclined surface 41b. The first inclined surface 41b is inclined upward from the first opening 43a on the air supply mechanism 50 side toward the second opening 44a on the intake mechanism 70 side, and is inclined up to the first wall surface H1 of the exit hole 41a. doing. Further, the bottom plate 41 becomes thicker from the exit hole 41a toward the second opening 44a, and the bottom plate 41 is provided with a second inclined surface 41c on the surface (upper surface) of the portion where the thickness becomes thicker. The second inclined surface 41c is inclined upward from the exit hole 41a toward the second opening 44a. Therefore, the flow path 46 connecting the first opening 43a and the second opening 44a has a portion that is inclined upward from the first opening 43a toward the second opening 44a.

The sputter cover 40 having the above configuration is placed on the tab 26 at the other end of the tab group 18 in the stacking direction via the welding jig 47. The welding jig 47 is made of ceramics or a metal having a low thermal conductivity. The welding jig 47 has a tubular shape and is placed at a position surrounding the welded portion 31 on the tab 26. Both end faces in the axial direction of the welding jig 47 are flat surfaces. The welding jig 47 has a through hole 47a penetrating in the axial direction. The through hole 47a has an elongated shape when viewed in the axial direction, and has the same shape as the exit hole 41a and the incident hole 45a of the sputtering cover 40.

Then, on the spatter cover 40, the bottom plate 41 is placed on the end surface of the welding jig 47. When the spatter cover 40 is placed on the welding jig 47, the through hole 47a of the welding jig 47 and the exit hole 41a of the bottom plate 41 communicate with each other. Therefore, the laser beam R incident on the incident hole 45a of the sputter cover 40 passes through the flow path 46 in a state of intersecting in the axial direction, is incident on the exit hole 41a, and further, the laser light incident on the emission hole 41a is emitted. , Penetrates the welding jig 47 and irradiates the tab group 18. The laser beam is scanned so as to pass through the incident hole 45a, the exit hole 41a, and the through hole 47a in this order.

The air supply mechanism 50 includes an air supply pipe 51 connected to one end of the spatter cover 40 in the axial direction. The air supply pipe 51 is arranged between the first short side wall 43 of the spatter cover 40 mounted on the welding jig 47 and the end surface 12a of the electrode assembly 12. The air supply pipe 51 includes a supply flow path 53 extending in the vertical direction inside. The air supply pipe 51 has a first pipe port 51a communicating with the supply flow path 53 at one end in the axial direction, and a second pipe port 51b communicating with the supply flow path 53 at the other end in the axial direction. The first pipe port 51a of the air supply pipe 51 communicates with the first opening 43a of the spatter cover 40. The opening edges of the first opening 43a of the sputter cover 40 and the first piping port 51a are in the same state. Therefore, the first inclined surface 41b is connected to one end edge 51c (lower end edge) of the first piping port 51a.

Of the end edges of the first pipe port 51a, one end edge 51c on the bottom side of the air supply pipe 51 and one end edge 43c of the first opening 43a are the other end edges Ha of the first wall surface H1 for partitioning the exit hole 41a. It is in a position (low position) that is out of alignment. In other words, the other end edge Ha of the first wall surface H1 is located at a position higher than the one end edge 51c, which is the bottom edge of the first piping port 51a.

Further, the bottom wall 52 of the air supply pipe 51 is inclined upward toward the first pipe port 51a. On the bottom side of the air supply pipe 51, a recess 52a that is recessed due to the inclination of the bottom wall 52 is formed.

The air supply mechanism 50 includes an air supply device 60 connected to a second pipe port 51b of the air supply pipe 51. The air supply device 60 supplies air to the flow path 46 of the spatter cover 40 via the supply flow path 53 of the air supply pipe 51.

As shown in FIG. 5 or 6, the intake mechanism 70 includes a duct 71 connected to the other end of the sputter cover 40 in the axial direction. The duct 71 includes a frame-shaped connecting portion 72 connected to the spatter cover 40 at one end in the axial direction. By connecting the duct 71 to the spatter cover 40 by the connecting portion 72, the inside of the duct 71 and the second opening 44a of the spatter cover 40 communicate with each other. The axial direction of the duct 71 is the same as the protruding direction of the tab 26 from the active material layer 25, and the duct 71 is not arranged outside the tab 26 in the lateral direction.

The intake mechanism 70 includes a suction pump 73 connected to the other end of the duct 71 in the axial direction. Then, by suction by the suction pump 73, the air flowing through the flow path 46 and flowing out from the second opening 44a is sucked into the duct 71.

In the laser welding apparatus 30, the spatter cover 40, the air supply mechanism 50, and the intake mechanism 70 are integrally assembled. The air supply pipe 51 of the air supply mechanism 50 is removable from the spatter cover 40, and the duct 71 of the intake mechanism 70 is also removable.

Next, a method of forming the welded portion 31 using the laser welding apparatus 30 will be described.
The method of forming the welded portion 31 includes a foil collecting step, a pressurizing step, and a welding step.
The foil collecting step is a step of collecting a plurality of tabs 26 included in the electrode assembly 12 to form a tab group 18. In the foil collecting step, first, all the tabs 26 of the electrode assembly 12 are arranged on the conductive member 17 placed on a work table (not shown). That is, the conductive member 17 is arranged outside (lower side) of the tab 26 at one end in the stacking direction.

Next, as shown in FIG. 4 or 5, the foil collecting device 62 presses all the tabs 26 from the opposite side (the other end side in the stacking direction) of the conductive member 17 sandwiching the tabs 26 to collect the foils. The tab group 18 is formed. The foil collecting device 62 includes a plate-shaped pressing member 63 that presses all the tabs 26, and also includes a fluid pressure cylinder 64 connected to the pressing member 63. The fluid pressure cylinder 64 is an air cylinder. The fluid pressure cylinder 64 includes a cylinder tube 64a and a cylinder rod 64b that appears and disappears from the lower end of the cylinder tube 64a. A piston 64c is movably housed in the cylinder tube 64a, and one end of the cylinder rod 64b is connected to the piston 64c. The upper surface of the pressing member 63 is connected to the other end of the cylinder rod 64b, which is a protruding end from the cylinder tube 64a. Then, by pressing the pressing member 63 mounted on the tab group 18 toward the tab group 18 by the fluid pressure cylinder 64, the tab group 18 can be pressurized in the stacking direction and foil can be collected.

The pressurizing step is a step of pressurizing the tab group 18 in the stacking direction by a welding jig 47 placed on the tab group 18 formed by the foil collecting step, and bringing the tabs 26 adjacent to each other in the stacking direction into close contact with each other. .. Further, in the pressurizing step, the welding jig 47 is placed on the tab group 18 in a state of surrounding the laser-welded portion.

The welding step is a step of forming the welded portion 31 by using the laser welding apparatus 30.
First, the spatter cover 40 is placed on the welding jig 47, and the spatter cover 40 is placed outside the tab 26 at the other end in the stacking direction. Then, the flow path 46 of the sputter cover 40 is in a state of extending from the boundary between the active material layer 25 of the positive electrode 21 and the negative electrode 22 and the tab 26 toward the tip end side of the tab 26.

Next, the laser welding device 30 is arranged on the outside of the spatter cover 40. At this time, a gap is formed between the spatter cover 40 and the pressing member 63 of the foil collecting device 62. Further, the through hole 47a of the welding jig 47 and the exit hole 41a of the spatter cover 40 are made to match.

Further, in the laser welding apparatus 30, an air supply pipe 51 is disposed between the first short side wall 43 of the spatter cover 40 and the end surface 12a of the electrode assembly 12, and the first pipe port 51a of the air supply pipe 51 is provided. , The first opening 43a of the spatter cover 40 communicates with the first opening 43a. The air supply pipe 51 of the air supply mechanism 50 is arranged closer to the tip of the tab 26 than the boundary between the active material layer 25 of the positive electrode 21 and the negative electrode 22 and the tab 26. In the present embodiment, the air supply pipe 51 is arranged closer to the tip of the tab 26 than the end surface 12a of the electrode assembly 12. Further, a duct 71 is arranged on the second short side wall 44 side of the spatter cover 40, and the inside of the duct 71 and the second opening 44a of the spatter cover 40 communicate with each other via the connecting portion 72.

Then, the air supply device 60 is driven to supply air to the flow path 46 of the sputtering cover 40 via the air supply pipe 51, and the suction pump 73 is driven to generate a suction force. Then, an air flow from the first opening 43a to the second opening 44a is formed in the sputtering cover 40. The air flows toward the second opening 44a by the first inclined surface 41b of the bottom plate 41, and further rises toward the second opening 44a by the second inclined surface 41c.

With the air flowing through the flow path 46, the laser beam R is irradiated from the laser irradiation device 48, and the laser beam R is incident on the incident hole 45a of the sputter cover 40. The laser beam R passes through the flow path 46, enters the exit hole 41a, and passes through the through hole 47a of the welding jig 47. Then, the laser beam R is emitted from the exit hole 41a and irradiates the tab 26 at the other end in the stacking direction in the tab group 18. After that, the laser beam R is scanned by the laser irradiation device 48, laser welding is performed, and the welded portion 31 is formed.

According to the above embodiment, the following effects can be obtained.
(1) The sputter cover 40 of the laser welding apparatus 30 can cover the periphery of the laser welded portion from the outside. Therefore, even if spatter occurs during laser welding, the spatter does not adhere to the periphery of the welded portion. Further, immediately after the generation, most of the spatter enters the exit hole 41a and adheres to the first to third wall surfaces H1 to H3, so that the scattering of the spatter itself is suppressed. Even if some of the spatter does not adhere to the first to third wall surfaces H1 to H3, the air forcibly supplied to the flow path 46 in the spatter cover 40 keeps it away from the laser welded portion. Further, it is sucked into the duct 71. Therefore, it is possible to prevent spatter from adhering to the periphery of the laser-welded portion, and it is possible to suppress spatter from adhering to the periphery of the welded portion 31.

(2) The air supply pipe 51 is arranged closer to the electrode assembly 12 than the spatter cover 40. Therefore, by supplying air from the air supply pipe 51 to the spatter cover 40, the air can flow in the direction away from the electrode assembly 12. Therefore, the supplied air can cause spatter to flow in a direction away from the electrode assembly 12, and thus the welded portion 31. Therefore, it is possible to prevent spatter from adhering not only to the periphery of the welded portion 31 but also to the electrode assembly 12.

(3) Most of the generated spatter adheres to the spatter cover 40. When the amount of spatter attached exceeds the specified value or the period of use of the spatter cover 40 exceeds a certain period, only the spatter cover 40 of the laser welding apparatus 30 needs to be replaced or cleaned. Compared with the case where the entire laser welding apparatus 30 is replaced, the maintenance of the laser welding apparatus 30 becomes easier.

(4) Of the first to third wall surfaces H1 to H3 that partition the ejection hole 41a of the spatter cover, the other end edge Ha of the first wall surface H1 closest to the first opening 43a is the first pipe of the air supply pipe 51. The position was higher than the one end edge 51c of the mouth 51a. Therefore, for example, as compared with the case where the other end edge Ha of the first wall surface H1 is at the same height as the one end edge 51c of the first piping port 51a, the area of the first wall surface H1 is increased and the first wall surface H1 Spatter easily adheres to the surface. As a result, it becomes difficult for spatter to enter the air supply pipe 51, and it is possible to prevent the air supply pipe 51 from being clogged with spatter.

(5) The laser welding apparatus 30 includes an intake mechanism 70 connected to the spatter cover 40. Therefore, the spatter flowing out from the spatter cover 40 can flow to the intake mechanism 70 and be recovered. Therefore, it is possible to prevent the spatter flowing out from the spatter cover 40 from adhering to a portion of the surface of the tab 26 that is distant from the laser welded portion or the lid 14.

(6) The flow path 46 is inclined upward from the air supply mechanism 50 (first opening 43a) side, which is the air inflow side, to the intake mechanism 70 (second opening 44a) side, which is the outflow side. Therefore, the spatter flowing through the air can be kept away from the tab group 18.

(7) The flow path 46 of the sputter cover 40 extends from the boundary side between the active material layer 25 and the tab 26 to the tip end side of the tab 26. Therefore, the spatter flowed by the air in the flow path 46 does not flow toward the other tab group 18, and it is possible to prevent the spatter from adhering to the other tab group 18.

(8) In the air supply pipe 51 of the air supply mechanism 50, the bottom wall 52 thereof is inclined upward toward the first pipe port 51a to form a recess 52a. Therefore, even if the spatter enters the supply flow path 53 of the air supply pipe 51 from the first pipe port 51a, it can be dropped into the recess 52a and collected.

(9) The thickness of the bottom plate 41 is gradually increased so as to have the first inclined surface 41b and the second inclined surface 41c. It can be kept away from 46. As a result, it is possible to prevent the air from hitting the laser-welded portion. Therefore, it is possible to suppress heat dissipation during laser welding, and it is possible to suppress a decrease in laser welding efficiency.

(10) The laser beam R passes through the incident hole 45a, the flow path 46, and the exit hole 41a of the sputtering cover 40 in this order. Since the flow path 46 through which air flows is interposed between the exit hole 41a and the incident hole 45a, even if the spatter jumps out of the exit hole 41a, it is flowed by the air flowing through the flow path 46 and the spatter is sent to the incident hole 45a. It is possible to suppress entry. As a result, it is possible to prevent spatter from adhering to the laser welding apparatus 30.

The above embodiment may be changed as follows.
○ The bottom plate 41 of the spatter cover 40 may have a shape extending flat in the horizontal direction instead of an upwardly inclined shape. Then, the other end edge Ha (upper end edge) of the first wall surface H1 that partitions the exit hole 41a may be at the same height as the one end edge 51c (lower end edge) of the first piping port 51a of the air supply pipe 51. ..

○ In the welding process, the spatter cover 40 may be directly placed on the tab group 18 without using the welding jig 47. Alternatively, the welding jig 47 may be integrated with the bottom plate 41 of the spatter cover 40.

○ The inner surface of the bottom wall 52 of the air supply pipe 51 has a flat surface extending in the horizontal direction, and the recess 52a may not be provided.
○ In the positive electrode 21 and the negative electrode 22, when the active material layer 25 is present near the root of the tab 26, the air supply pipe 51 of the air supply mechanism 50 and the flow path 46 of the spatter cover 40 are formed by the metal foil 24 on the tab 26. It is arranged closer to the tip of the tab 26 than the boundary between the portion of the tab 26 and the active material layer 25.

○ In the intake mechanism 70, the connecting portion 72 of the duct 71 does not have to have a shape surrounding the spatter cover 40, and may be directly connected to the second opening 44a.
○ The flow path 46 of the spatter cover 40 may be bent in the spatter cover 40. For example, one end of the flow path 46 is a first opening 43a, the other end is an opening formed in one of a pair of long side walls 42, and the intake mechanism 70 is connected to the opening of the long side wall 42. In this case, it is preferable that the intake mechanism 70 is arranged on the short edge side of the tab 26 in the lateral direction, which is farther from the other tab group 18.

○ In the laser welding apparatus 30, the spatter cover 40, the air supply mechanism 50, and the intake mechanism 70 may be integrally formed so that the spatter cover 40 cannot be attached to or detached from the air supply pipe 51 and the duct 71.

○ The electrode assembly 12 may be a winding type electrode assembly. Although not shown, the wound electrode assembly has a layered structure in which a long strip-shaped positive electrode and a long strip-shaped negative electrode are insulated from each other. Each of the positive electrode and the negative electrode has a strip-shaped uncoated portion in which the active material layer does not exist at one of the edges along the pair of long sides and the metal foil is exposed. The electrode assembly includes a group of uncoated portions in which strip-shaped uncoated portions are laminated with the same polarity. The uncoated portion group of the positive electrode exists at one end of the winding axis, and the uncoated portion group of the negative electrode exists at the other end of the winding axis.

○ In the positive electrode 21 and the negative electrode 22, the active material layer 25 may be present on one side of the metal foil 24.
○ The uncoated portion of the positive electrode 21 and the negative electrode 22 is not limited to the tab 26. For example, the metal foil 24 is exposed from one of the edges of the pair of long sides of the positive electrode 21 and the negative electrode 22, and the tab 26 is projected from a part of the exposed metal foil. Then, the metal foil and the tab 26 along the edge portion may be used as the uncoated portion. Further, the metal leaf 24 may be exposed from one of the edges of the pair of long sides of the positive electrode 21 and the negative electrode 22, and only the exposed portion may be an uncoated portion.

○ A protective plate may be placed on the tab group 18 and laser welding may be performed.
○ The length of the welded portion 31 may extend in the longitudinal direction of the tab 26.
○ The length of the welded portion 31 in the longitudinal direction may be appropriately changed.

○ The shape of the welded portion 31 may be changed as appropriate.
○ The power storage device can also be applied to a power storage device other than a secondary battery, such as a capacitor.

○ The secondary battery 10 may be a secondary battery other than the lithium ion secondary battery. In short, it suffices as long as the ions move between the active material for the positive electrode and the active material for the negative electrode and the charge is taught.

Next, the technical idea that can be grasped from the above embodiment and another example will be added below.
(1) A laser welding device in which the flow path is inclined upward from the air supply mechanism side toward the intake mechanism side.

(2) A laser welding device in which the flow path extends from the air supply mechanism side toward the intake mechanism side in the direction of protrusion of the uncoated portion from the active material layer.
(3) The air supply mechanism includes an air supply pipe and an air supply device connected to the air supply pipe. The air supply pipe has a supply flow path extending in the vertical direction inside, and the bottom wall is spattered. A laser welding device that is formed by inclining up toward the cover.

H1 to H3 ... 1st to 3rd wall surfaces, Ha ... other end edge, R ... laser light, 10 ... secondary battery as a power storage device, 12 ... electrode assembly, 12a ... end face, 17 ... conductive member, 18 ... not yet Tab group as a coated part group, 21 ... Positive electrode as a positive electrode, 22 ... Negative electrode as a negative electrode, 24 ... Metal foil, 25 ... Active material layer, 26 ... Tab as an uncoated part, 30 ... Laser welding device, 31 ... Welded part, 40 ... Spatter cover, 41 ... Bottom plate, 41a ... Outlet hole, 43c ... One end edge, 45 ... Top plate, 45a ... Incident hole, 46 ... Flow path, 50 ... Air supply mechanism , 51c ... One end edge, 70 ... Intake mechanism.

Claims (2)

A structure in which positive electrode and negative electrode having an active material layer on at least one side of the metal foil and having an uncoated portion where the active material layer does not exist and the metal foil is exposed is laminated in an insulated state. A power storage device including an electrode assembly having an uncoated portion group having the uncoated portions laminated with the same polarity on one end surface, and a conductive member joined to the uncoated portion group. In the apparatus, it is a laser welding apparatus for forming a welded portion by laser welding the conductive member and the uncoated portion group.
In the welded portion, the conductive member is arranged outside the uncoated portion at one end in the stacking direction of the uncoated portion group, and from the outside of the uncoated portion at the other end in the stacking direction of the uncoated portion group. Formed by irradiating laser light
The uncoated portion group is arranged outside the uncoated portion at the other end in the stacking direction, and is provided inside with a hollow box-shaped spatter cover that allows air and the laser beam to pass through. It has the air flow path extending from the boundary side between the material layer and the uncoated portion to the tip end side of the uncoated portion, and penetrates the bottom plate through the bottom plate covering the uncoated portion at the other end in the stacking direction. The top plate facing the bottom plate has an incident hole for the laser light that penetrates the top plate, and the spatter cover has the incident hole, the flow path, and the incident hole. The laser beam passes in the order of the exit holes,
An air supply mechanism that communicates with one end of the flow path of the sputter cover is provided, and the air supply mechanism is closer to the tip of the uncoated portion than the boundary between the active material layer and the uncoated portion. Disposed between the end face of the electrode assembly and the spatter cover,
A laser welding apparatus including an intake mechanism communicating with the other end of the flow path of the spatter cover. Of the wall surfaces that partition the exit holes of the spatter cover, the edge of the wall surface that is closest to one end of the flow path and that faces the flow path is an opening of the air supply mechanism that communicates with one end of the flow path. The laser welding apparatus according to claim 1, which is located higher than the bottom edge.

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