JP5002984B2 - Manufacturing method and manufacturing apparatus of assembled battery - Google Patents

Description

The present invention relates to a method and apparatus for manufacturing a battery pack. In particular, the present invention relates to a method and apparatus for manufacturing a battery assembly formed by joining a plurality of electrode tabs derived from the adjacent flat batteries to each other.

  Secondary batteries such as lithium ion batteries and nickel metal hydride batteries are actively developed as power sources for driving motors of electric vehicles and hybrid electric vehicles.

  As a motor drive power source, a set of a plurality of flat unit cells in which a power generation element in which a positive electrode plate and a negative electrode plate are laminated is sealed in an exterior member such as a laminate film is laminated and electrically connected. A battery is used. In such an assembled battery, electrode tabs derived from the exterior members of a plurality of adjacent unit cells are joined to each other by an ultrasonic joining method (for example, Patent Document 1).

When the assembled battery is mounted on a vehicle, fatigue damage may occur at the joint portions of the electrode tabs that are joined to each other by vibration during driving of the motor. From the viewpoint of ensuring the performance and reliability of the assembled battery, it is indispensable to manage the strength of the joint portions of the electrode tabs joined to each other. However, the fatigue fracture strength with respect to the vibration of the electrode tab joined by the ultrasonic joining method is unknown.
JP 2000-251882 A

  The present invention has been made to solve the above-described problems. Accordingly, an object of the present invention is to provide a method and an apparatus for manufacturing an assembled battery having enhanced fatigue fracture strength against vibration of electrode tabs.

  The above object of the present invention is achieved by the following means.

The method of the battery pack manufacturing the present invention is a manufacturing method of an assembled battery formed by joining to each other a plurality of plate-shaped electrode tabs derived from flat battery, super into a pair of electrode tabs superimposed A first joining step for ultrasonically joining the electrode tabs by applying ultrasonic vibration; and a second joining step for caulking and joining the electrode tabs by plastic deformation of the electrode tabs ultrasonically joined in the first joining step. If, have a, ultrasonic bonding area of the electrode tabs are ultrasonically bonded in the first bonding step is formed so as to surround the unbonded region, the second bonding step, the ultrasonic bonding region It is characterized by caulking and joining the unjoined region surrounded .

Manufacturing of the assembled battery of the present invention is directed to an apparatus for producing a battery assembly formed by joining to each other a plurality of plate-shaped electrode tabs derived from flat battery, super into a pair of electrode tabs superimposed and ultrasonic bonding unit for ultrasonic bonding the electrode tabs by adding ultrasonic vibration, and a crimped portion for caulking joining the electrode tabs by plastically deforming the electrode tabs are ultrasonically bonded by the ultrasonic bonding portion , have a, the ultrasonic bonding area of the electrode tabs are ultrasonically bonded by the ultrasonic bonding portion is formed so as to surround the unbonded region, the crimped portion is surrounded by the ultrasonic bonding region Further, it is characterized in that the unjoined region is crimped .

  According to the method and apparatus for manufacturing an assembled battery of the present invention, a set of superimposed electrode tabs are bonded together using a plurality of bonding methods. Therefore, the fatigue fracture strength against the vibration of the electrode tab can be enhanced.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol was used for the same member in the figure.

  FIG. 1 is a block diagram showing a schematic configuration of an assembled battery manufacturing apparatus according to an embodiment of the present invention. As shown in FIG. 1, the assembled battery manufacturing apparatus 100 according to the present embodiment includes an ultrasonic bonding portion 200 and a caulking bonding portion 300.

  FIG. 2 is a perspective view showing the ultrasonic bonding portion in the present embodiment. The ultrasonic bonding portion 200 according to the present embodiment ultrasonically bonds the electrode tabs by applying ultrasonic vibrations to a pair of electrode tabs that are superimposed. As shown in FIG. 2, the ultrasonic bonding unit 200 includes a horn 210 that presses an electrode tab while being reciprocated linearly by ultrasonic vibration, and an anvil 220 that supports the electrode tab pressed by the horn 210. . In this Embodiment, each surface which pinches | interposes the electrode tab of the horn 210 and the anvil 220 is a rectangle, Comprising: It has the cylindrical recessed parts 211 and 221 in the center part, respectively.

  FIG. 3 is a perspective view showing a caulking joint portion in the present embodiment. The crimping joint 300 of the present embodiment is for crimping and joining the electrode tabs by plastically deforming the electrode tabs that have been ultrasonically joined. As shown in FIG. 3, the caulking joint 300 is a punch 310 that is a first mold that is pushed into the electrode tab, and a second mold that is arranged to face the punch 310 and supports the electrode tab. And a certain die 320. In the present embodiment, the thickness of the electrode tab is set on the periphery of the protrusion 311 protruding from the mold surface of the punch 310 and the periphery of the recess 321 of the die 320 provided to engage with the protrusion 311. Corresponding concave step portions 312 and 322 are provided, respectively. In addition, an annular relief groove 323 is formed on the bottom surface of the recess 321.

  In manufacturing apparatus 100 according to the present embodiment configured as described above, the overlapped plate-like electrode tabs are joined by ultrasonic joining, and further joined by caulking joining. Hereinafter, the electrode tab joining method according to the present embodiment will be described with reference to FIGS.

  FIG. 4 is a flowchart showing the manufacturing process of the assembled battery in the present embodiment, and FIG. 5 is a cross-sectional view for explaining the ultrasonic bonding process of the electrode tab in the present embodiment.

  First, as shown in FIGS. 4 and 5A, a set of electrode tabs 400a and 400b (hereinafter collectively referred to as electrode tabs 400) superimposed on the anvil 220 of the ultrasonic bonding portion 200 are provided. It is mounted (step S101).

  Next, the horn 210 is pressed against the electrode tab 400 placed on the anvil 220, and the electrode tab 400 is ultrasonically bonded (step S102). More specifically, as shown in FIG. 5B, the ultrasonic bonding unit 200 sandwiches a pair of electrode tabs 400 that are overlapped by a horn 210 and an anvil 220, and applies a predetermined pressure force. The electrode tab 400 is joined by reciprocating linear movement of the horn 210 by ultrasonic vibration. Therefore, by rubbing the contact surfaces of the two electrode tabs 400, impurities such as oxide films are removed, the clean surfaces of the electrode tabs 400 are brought into contact with each other, and the electrode tabs 400 are fixed by the generated frictional heat. Phase bonded.

  As described above, the horn 210 and the anvil 220 in the present embodiment have the cylindrical recesses 211 and 221 on each surface that sandwich the electrode tab 400. In such a configuration, at the time of ultrasonic bonding, the region of the electrode tab 400 positioned below the cylindrical recesses 211 and 221 is not pressurized and thus is not ultrasonically bonded. As a result, the electrode tab 400 subjected to ultrasonic bonding can leave a circular unbonded region 420 at the center of the rectangular ultrasonic bonding region 410 formed by ultrasonic bonding.

  FIG. 6 is a diagram showing an electrode tab after ultrasonic bonding and an electrode tab bonded by a general ultrasonic bonding method in the present embodiment. As shown in FIG. 6A, the ultrasonic bonding region 410 of the electrode tab 400 bonded by the ultrasonic bonding method of the present embodiment is formed in a rectangular shape so as to surround a circular unbonded region 420 at the center. Is done. The circular unbonded region 420 is crimped in a subsequent crimping process. The plate thickness of the unbonded region 420 of the electrode tab 400 is thicker than the plate thickness of the ultrasonic bonded region 410 that is ultrasonically bonded. With such a configuration, the strength of the electrode tab 400 against caulking joining described later is ensured, and the electrode tab 400 is prevented from being damaged during caulking joining.

From the viewpoint of securing the current density, in this embodiment, the rectangular dimension of the ultrasonic bonding region is larger than that in the case where the electrode tab is bonded only by ultrasonic bonding as shown in FIG. It is desirable to take a large value. More specifically, the size L ₁ of the ultrasonic bonding region 410 in the electrode tab 400 of the present embodiment is larger than the dimension L ₂ of the ultrasonic bonding area of the common electrode tabs.

  FIG. 7 is a cross-sectional view for explaining the caulking joining process of the electrode tab in the present embodiment.

  As shown in FIG. 4 and FIG. 7A, the set of electrode tabs 400 ultrasonically bonded by the ultrasonic bonding method is moved and placed on the die 320 of the caulking bonding part 300 (step S103). ).

  7B, the convex portion 311 of the punch 310 is pushed into the electrode tab 400 placed on the die 320, and the electrode tab 400 is crimped and joined (step S104). As described above, in the present embodiment, the caulking joint 300 caulks and joins the circular unjoined region 420 surrounded by the ultrasonic joining region 410. Note that the circular unbonded region 420 is desirably located at the center of the rectangular ultrasonic bonding region 410.

  In the present embodiment, an annular relief groove 323 is formed on the bottom surface of the recess 321. With such a configuration, when the punch 310 is pushed into the electrode tab 400, a part of the lower electrode tab 400b is plastically deformed so as to escape into the escape groove 323 below the recess 321. The electrode tab 400a protrudes toward the lower electrode tab 400b and plastically deforms so as to bulge in a direction to escape in the surface direction. As a result, the electrode tab 400a and the electrode tab 400b are concavo-convexly engaged with each other. Therefore, the electrode tabs 400 can be fixed so as not to be separated from each other.

Furthermore, as described above, in the present embodiment, the peripheral edge of the convex portion 311 protruding from the mold surface 313 of the punch 310 and the peripheral edge of the concave portion 321 of the die 320 provided to engage with the convex portion 311 are provided. Recessed step portions 312 and 322 corresponding to the plate thickness of the electrode tab are provided, respectively. The electrode tab 400 that is ultrasonically bonded has an ultrasonic bonding region 410 and an unbonded region 420 that is thicker than the ultrasonic bonding region 410, and the depth of the recessed step portions 312 and 322 is super This corresponds to the difference in plate thickness between the sonic bonding region 410 and the unbonded region 420. More specifically, the depths d ₁ and d ₂ of the recessed step portions 312 and 322 coincide with the plate thickness differences d ₃ and d ₄ between the ultrasonic bonding region 410 and the unbonded region 420, respectively.

  With such a configuration, the pull-in of the electrode tab 400 during caulking bonding is suppressed, and strength deterioration of the ultrasonic bonding area 410 due to caulking bonding is prevented. Further, in the electrode tab moving process shown in step S103, the electrode tab 400 is arranged along the recessed step portions 312 and 322, so that the positioning of the electrode tab 400 to be crimped is facilitated.

  Finally, the crimped and joined electrode tab 400 is taken out from the crimped joint 300, and the process is terminated (step S105).

  In this embodiment, in ultrasonic bonding, the electrode tab is ultrasonically bonded so as to surround a circular unbonded region at the center, and the circular unbonded region is bonded by caulking bonding. However, the unjoined region left by the ultrasonic joining is not limited to a circle, and may be formed so as to be surrounded by the ultrasonic joining region. With such a configuration, the area of the bonding region (bonding spot) can be reduced.

  Furthermore, in the present embodiment, the ultrasonic bonding region is formed so as to surround the non-bonded region, and the non-bonded region is crimped by a caulking bonding method. However, the caulking joint can be caulked and joined not only to the unjoined area but also to an area that at least partially overlaps the ultrasonic joining area. In other words, the caulking joining point can be overprinted with respect to the joining point by the ultrasonic bonding method.

  As described above, the manufacturing apparatus and the manufacturing method of the assembled battery in the present embodiment have been described. Next, the assembled battery manufactured by the assembled battery manufacturing method of the present embodiment will be described.

  FIG. 8 is a perspective view showing an assembled battery according to an embodiment of the present invention. In the present embodiment, the flat battery that constitutes the assembled battery by being stacked in the thickness direction is, for example, a lithium ion battery.

  As shown in FIG. 8, in the assembled battery 500 of the present embodiment, the plate-like electrode tabs 400 led out from the adjacent flat batteries 600 are joined to each other by an ultrasonic joining method and a caulking joining method. ing. More specifically, the positive electrode tab 400a of the first cell 610 is joined to the negative electrode tab 400b of the second cell 620 by ultrasonic bonding and caulking bonding. Similarly, the positive electrode tab 400a of the second cell 620 is the negative electrode tab 400b of the third cell 630, and the positive electrode tab 400a of the third cell 630 is the negative electrode tab of the fourth cell 640. 400b is joined by an ultrasonic joining method and a caulking joining method.

  In addition, as shown in the cross-sectional view of the electrode tab shown in FIG. 7B, in the pair of electrode tabs 400 derived from the adjacent flat unit cell 600, the upper electrode tab 400a is the lower electrode tab 400b. Bulges in the surface direction. As a result, the upper electrode tab 400a and the lower electrode tab 400b are in concavo-convex engagement with each other. The lower electrode tab 400b has an annular relief portion that allows the upper electrode tab 400a to bulge. That is, in the assembled battery 500 of the present embodiment, one electrode tab 400a is crimped and joined to the other electrode tab 400b so as not to be detached. Further, a rectangular region surrounding the crimped region 430 is an ultrasonic bonding region 420 that is solid-phase bonded by ultrasonic bonding.

  In the present embodiment, the shape of the electrode tabs 400 to be joined to each other is not limited to the shape shown in FIG. 8, and can take various shapes as shown in FIG. FIG. 9 is a perspective view of a unit cell showing another shape of the electrode tab in the present embodiment. As shown in FIG. 9, the electrode tab 400 of the unit cell 600 is formed so as to have a recess, or is formed so as to have a smaller width than the electrode tab of the present embodiment. With such a configuration, when the adjacent electrode tabs 400 are joined while the unit cells 600 are stacked, the other electrode tabs 400 that have been joined are positioned above the electrode tabs 400 that are to be joined. This avoids a situation in which the electrode tab 400 that is not a member needs to be joined while the electrode tab 400 is plastically deformed.

  Next, the effect of the assembled battery 500 in this Embodiment is demonstrated compared with a general assembled battery. FIG. 10 is a diagram for explaining the function and effect of the assembled battery in the present embodiment. FIG. 10A is a diagram showing the assembled battery joining process in the present embodiment, and FIG. 10B is a diagram showing a general assembled battery joining process.

  As shown in FIG. 10B, in a general assembled battery, two ultrasonic bonding regions are formed on one set of electrode tabs in order to ensure sufficient fatigue fracture strength. On the other hand, as shown in FIG. 10A, in the assembled battery 500 in the present embodiment, only one ultrasonic bonding region 420 is formed on one set of electrode tabs 400, and further, the ultrasonic bonding region The area surrounded by 420 is crimped. Therefore, the length of the electrode tab 400 can be shortened in the assembled battery 500 according to the present embodiment as compared with a general assembled battery.

FIG. 11 is a diagram showing a battery pack composed of the assembled battery of the present embodiment and a general battery pack. The battery pack 700 of the present embodiment is configured by accommodating five sets of assembled batteries 500 in which a plurality of unit cells 600 are stacked in the thickness direction. In the battery pack 700, the assembled batteries 500 are electrically connected to each other. As shown in FIG. 11, according to the assembled battery 500 of the present embodiment, the volume of the battery pack 700 can be reduced, and the volume energy density of the battery pack 700 can be increased. More specifically, the dimension L ₃ of the battery pack 700 of the present embodiment is formed smaller than the dimension L ₄ of a general battery pack, and as a result, the volume of the battery pack 700 of the present embodiment is reduced. It can be made smaller than a general battery pack. Note that the battery pack 700 itself is also included in an assembled battery including a plurality of single cells.

  As described above, the described embodiment has the following effects.

  The manufacturing apparatus according to the present embodiment includes an ultrasonic bonding unit that bonds a pair of superimposed electrode tabs by an ultrasonic bonding method, and a crimping method that further bonds the electrode tabs bonded by an ultrasonic bonding method by a caulking bonding method. And a joint portion. Therefore, the load applied to the bonded electrode tab is shared between the ultrasonic bonding region and the crimping bonding region, and the load can be reduced. As a result, the fatigue fracture strength against the vibration of the electrode tab can be enhanced.

  The caulking joining portion caulks and joins an area at least partially overlapping with the ultrasonic joining area of the electrode tab ultrasonically joined by the ultrasonic joining method. Therefore, the area of the bonding region can be omitted, and as a result, the area of the electrode tab can be reduced.

  The ultrasonic bonding area of the electrode tab to be ultrasonically bonded by the ultrasonic bonding method is formed in a rectangular shape so as to surround the circular unbonded area at the center, and the crimped bonding portion is surrounded by the rectangular ultrasonic bonding area. The circular unbonded area thus formed is crimped. Therefore, the area of the joining region is omitted and the electrode tab is prevented from being damaged by caulking joining. Furthermore, it is possible to easily join the electrode tabs using a commercially available crimping machine.

  The caulking joint portion has a pair of molds including a punch and a die, and is provided on the peripheral edge of the convex portion protruding from the punch mold surface and the peripheral edge of the concave portion of the die provided to engage with the convex portion. Are each provided with a concave step corresponding to the plate thickness of the electrode tab. Therefore, the pull-in of the electrode tab at the time of caulking is prevented. As a result, strength deterioration of the ultrasonic bonding region during caulking bonding is suppressed, and the electrode tab can be easily positioned during caulking bonding.

  The depth of the concave step portion corresponds to the difference in plate thickness between the ultrasonic bonding region and the non-bonding region. Therefore, the pull-in of the electrode tab at the time of caulking joining is further prevented.

  The manufacturing method of the present embodiment includes a first joining step of joining a pair of electrode tabs that are overlapped by an ultrasonic joining method, and a step of further joining the electrode tabs joined by an ultrasonic joining method by a caulking joining method. Two joining stages. Therefore, the load applied to the bonded electrode tab is shared between the ultrasonic bonding region and the crimping bonding region, and the load can be reduced. As a result, the fatigue fracture strength against the vibration of the electrode tab can be enhanced.

  In the assembled battery of the present embodiment, plate-like electrode tabs derived from adjacent flat batteries are joined to each other by an ultrasonic joining method and a caulking joining method. Therefore, the fatigue fracture strength against the vibration of the electrode tab is enhanced, the performance of the assembled battery is ensured and the reliability is ensured. Furthermore, according to the assembled battery of the present embodiment, the volume of the assembled battery and the battery pack can be reduced, and the volume energy density of the battery pack can be increased.

  The flat battery is a lithium ion battery. Therefore, a high output assembled battery can be provided.

  As an effect, the mechanical contact strength between the electrode tabs can be sufficiently secured by the addition of the caulking joint while the electrical contact resistance between the electrode tabs is sufficiently lowered by the ultrasonic joint.

  As described above, in the embodiment of the present invention, the method and apparatus for manufacturing the assembled battery of the present invention and the assembled battery manufactured by this manufacturing method have been described. However, it goes without saying that the present invention can be appropriately added, modified, and omitted by those skilled in the art within the scope of the technical idea.

  For example, in one embodiment of the present invention, the electrode tab is bonded by using both the ultrasonic bonding method and the caulking bonding method. However, the present invention is not limited to this, and bonding methods such as bending bonding and flange bonding can be used. In addition, the electrode tab can be joined by combining three or more joining methods.

It is a block diagram which shows schematic structure of the manufacturing apparatus of the assembled battery in one embodiment of this invention. It is a perspective view which shows the ultrasonic bonding part in the manufacturing apparatus shown by FIG. It is a perspective view which shows the crimping joint part in the manufacturing apparatus shown by FIG. It is a flowchart which shows the manufacturing process of the assembled battery in the joining apparatus shown by FIG. It is sectional drawing for demonstrating the ultrasonic bonding process of the electrode tab in the ultrasonic bonding part shown by FIG. It is a figure which shows the electrode tab joined by general ultrasonic bonding, and the electrode tab after the ultrasonic bonding process shown by FIG. It is sectional drawing for demonstrating the crimping joining process of the electrode tab in the crimping junction part shown by FIG. It is a perspective view which shows the assembled battery in one embodiment of this invention. It is a perspective view of the cell which shows the other shape of the electrode tab in the assembled battery shown by FIG. It is a figure for demonstrating the effect of the assembled battery shown by FIG. It is a figure which shows the battery pack comprised by the assembled battery shown by FIG. 8, and a general battery pack.

Explanation of symbols

100 joining device,
200 Ultrasonic joint,
300 caulking joint,
400 electrode tabs,
500 battery packs,
600 cells,
700 battery pack.

Claims (10)

A method for producing an assembled battery in which a plurality of plate-like electrode tabs derived from a flat battery are joined to each other,
A first bonding step of ultrasonically bonding the electrode tabs by applying ultrasonic vibrations to the set of electrode tabs superimposed;
Have a, a second bonding step of staked the electrode tabs by plastically deforming the electrode tabs are ultrasonically bonded in the first bonding step,
The ultrasonic bonding region of the electrode tab to be ultrasonically bonded in the first bonding step is formed so as to surround the unbonded region,
In the second bonding step, the unbonded region surrounded by the ultrasonic bonding region is caulked and bonded . The ultrasonic bonding region is formed in a rectangular shape so as to surround a circular unbonded region in the center,
2. The method of manufacturing an assembled battery according to claim 1 , wherein the second joining step includes caulking joining of a circular unjoined region surrounded by the rectangular ultrasonic joining region. The second bonding step includes a step of caulking and bonding the electrode tab using a pair of molds,
In the mold, a concave step portion corresponding to the plate thickness of the electrode tab is provided on the peripheral edge of the convex portion protruding from the mold surface and the peripheral edge of the concave portion provided to engage with the convex portion. The method for producing an assembled battery according to claim 1, wherein the battery pack is manufactured. The ultrasonically bonded electrode tab has an ultrasonic bonding region and an unbonded region having a plate thickness larger than the ultrasonic bonding region,
The depth of the said recessed level | step-difference part respond | corresponds to the difference of the plate | board thickness of the said ultrasonic joining area | region and a non-joining area | region, The manufacturing method of the assembled battery of Claim 3 characterized by the above-mentioned. The flat battery, a method of manufacturing a battery pack according to any one of claims 1 to 4, characterized in that a lithium ion battery. A battery assembly manufacturing apparatus in which a plurality of plate-like electrode tabs derived from a flat battery are joined to each other,
An ultrasonic bonding part that ultrasonically bonds the electrode tabs by applying ultrasonic vibrations to the set of superimposed electrode tabs;
Have a, a crimped portion for caulking joining the electrode tabs by causing the plastic deformation of the electrode tabs are ultrasonically bonded by ultrasonic bonding unit,
The ultrasonic bonding region of the electrode tab to be ultrasonically bonded by the ultrasonic bonding portion is formed so as to surround the unbonded region,
The assembled battery manufacturing apparatus according to claim 1, wherein the crimping joint caulks and joins an unjoined region surrounded by the ultrasonic joining region . The ultrasonic bonding region is formed in a rectangular shape so as to surround a circular unbonded region in the center,
The assembled battery manufacturing apparatus according to claim 6, wherein the caulking joining portion caulks and joins a circular unjoined region surrounded by the rectangular ultrasonic joining region. The caulking joint is caulking and joining the electrode tab using a pair of molds,
In the mold, a concave step portion corresponding to the plate thickness of the electrode tab is provided on the peripheral edge of the convex portion protruding from the mold surface and the peripheral edge of the concave portion provided to engage with the convex portion. The assembled battery manufacturing apparatus according to claim 6 or 7, wherein the apparatus is manufactured. The ultrasonically bonded electrode tab has an ultrasonic bonding region and an unbonded region having a plate thickness larger than the ultrasonic bonding region,
The depth of the said recessed level | step-difference part respond | corresponds to the difference of the plate | board thickness of the said ultrasonic joining area | region and a non-joining area | region, The manufacturing apparatus of the assembled battery of Claim 8 characterized by the above-mentioned. The assembled battery manufacturing apparatus according to claim 6, wherein the flat battery is a lithium ion battery.

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