JP2001038475A - Jointing method of laminating material, and battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a jointing method to perform jointing without damaging a sheet like member constituting a laminating material when a laminating material and a jointed material are jointed. SOLUTION: In this jointing method of a laminating material, an ultrasonic wave vibration is provided to a laminating material 1 having such a structure that sheet-like members are laminated and a jointed member 2 overlapped on the laminating material 1, so as to joint the sheet-like members of the laminating material 1, and the laminating material 1 and the jointed member 2. The jointed member 2 has a protrusion part 22 protruding at the overlapped part of the laminating material 1, and the ultrasonic vibration is provided under the condition that the protrusion part 22 presses the laminating material 1. Further, a protrusion part is formed on the jointing face of the jointed member against the laminating material 1, and an ultrasonic wave amplitude energy in an ultrasonic jointed method is locally absorbed and diffused, so as to make a process in the ultrasonic jointing to be a highly efficient.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for joining a laminate in which sheet-like members are laminated and a member to be joined by an ultrasonic joining method. In particular, the present invention relates to a joining method used for joining an electrode plate and a current extraction terminal in a battery.

[0002]

2. Description of the Related Art In recent years, batteries used for automobile batteries and the like have also been required to have higher performance. More specifically, high output and high energy density of automobile batteries are required, and nickel-metal hydride secondary batteries and lithium ion secondary batteries can be mentioned as secondary batteries that satisfy these requirements.

[0003] Further, such a secondary battery has an electrode body in which a positive electrode and a negative electrode are arranged to face each other in a sealed battery case. In this secondary battery, an electrode reaction occurs between the positive electrode and the negative electrode arranged opposite to each other, and current is taken out using external terminals electrically connected to the positive electrode and the negative electrode, respectively. Further, the electrode body is required to have a large electrode plate area in order to improve the current density of the battery, and the sheet-like positive electrode plate and the negative electrode plate are laminated or wound in a state where they face each other. It is an electrode body.

Here, in a conventional small secondary battery,
The connection between the electrode body composed of the positive electrode and the negative electrode and the external terminal has been made by joining a thin tab (one) provided on the electrode plate.

However, in a battery requiring a large current, such as a battery for an automobile, a structure in which the current is efficiently extracted by increasing the number of tabs, or a structure in which the active material is not provided on the electrode plate of the laminated or wound electrode body. By making a coated part and joining the uncoated part directly to the terminal collectively,
High performance is being promoted. In such a means for improving performance, ultrasonic bonding is often used as a method of bonding a large area in a short time for connection between an electrode and a terminal.

However, in the ultrasonic bonding of the multilayer body of the sheet-like electrode plates and the current extraction terminals, the number of stacked electrode plates is increased when the layers of the electrode plates and the current extraction terminals are integrally joined. Accordingly, it was necessary to increase the output of the ultrasonic energy applied at the time of bonding. However, when an attempt is made to satisfy the bonding condition under the conditions in the high-power region, excessive stress is applied to the bonding portion and the vicinity of the bonding portion, and the sheet-like electrode plate constituting the electrode body is broken due to insufficient strength. Had the problem that

In particular, in the case of a lithium ion secondary battery, aluminum and copper are generally used for an electrode plate and a current extraction terminal, but since these materials are difficult to bond, they are used for a sheet-like electrode plate. It was a difficult technique to obtain a perfect joint without causing damage.

As described above, it has been difficult to integrally join different kinds of members to a laminate having a structure in which sheet-like members are laminated.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and does not damage a sheet-like member constituting a laminate when joining the laminate and an object to be joined. It is an object to provide a joining method capable of joining.

[0010]

Means for Solving the Problems In order to solve the above problems, the present inventors have repeatedly studied the ultrasonic bonding method, and as a result, the member to be bonded has a protrusion, and the protrusion overlaps with the laminate. It has been found that the above-mentioned problem can be solved by applying ultrasonic vibration in a state where the vibration is applied.

[0011] That is, the method for bonding a laminate according to the present invention comprises:
A laminate having a structure in which sheet-like members are laminated, and a member to be joined superimposed on the laminate, and ultrasonic vibration is applied to the sheet-like members of the laminate and the laminate and the member to be joined. A joining method of a laminate to be joined, wherein the member to be joined has a projection projecting from an overlapping portion with the laminate, and ultrasonic vibration is applied in a state where the projection presses the laminate. It is characterized by.

According to the method of joining a laminate of the present invention, a projection is formed on a joint surface of a member to be joined with the laminate to locally absorb and diffuse ultrasonic amplitude energy in the ultrasonic joining method. The efficiency of the ultrasonic bonding process is improved. Therefore, heat generation, breakage, and biting of the horn due to the ultrasonic vibration are suppressed in the bonding portion and the vicinity of the bonding portion of the laminate, and the quality of the bonding surface is improved.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The method of joining a laminate according to the present invention is a joining method in which a laminate and a member to be joined having a projection are joined by applying ultrasonic vibration in a superposed state. .

The method for bonding a laminate according to the present invention is performed by an ultrasonic bonding method of applying ultrasonic vibration in a state where the laminate and the member to be bonded are superposed. The ultrasonic bonding method applies ultrasonic vibration to two abutting members, causing the abutting surfaces to relatively vibrate, and the energy of the vibration causes atoms on the surfaces to move and diffuse. It is joined by doing.

The laminate is formed by laminating sheet members.

The member to be joined has a projection projecting from a portion where the member is overlapped with the laminate. By having this projection,
Ultrasonic amplitude energy applied at the time of ultrasonic bonding can be locally applied, and the laminate and the member to be bonded are integrally bonded.

That is, when the member to be joined is overlapped with the laminate, the projections provided on the member to be joined locally press the laminate. That is, the protrusion presses the laminate, the pressing area decreases, and the pressing force for pressing the laminate increases.

The laminate is preferably formed by laminating or winding sheet-like members. That is, the laminate only needs to have a structure in which the sheet-like members are laminated at the joint with the member to be joined. Examples of such a structure include a laminated body and a wound body of a sheet-like member.

The projection is preferably formed in a conical shape. That is, since the projection is formed in a conical shape narrowed toward the distal end, the projection locally presses the stacked body at the overlapping portion. Here, the conical shape of the protruding portion refers to a shape that is narrowed toward the distal end, not only a cone or a pyramid having a sharp distal end, but also a frustum having a shape in which the distal end of the cone or the pyramid is chipped. Also includes shape.

It is preferable that the protrusion has a height substantially equal to the thickness of the laminated body in the overlapped portion. That is, if the height of the protrusion is too low, the local pressure of the laminate by the protrusion is insufficient, and if the height is high, the protrusion damages the sheet-like member constituting the laminate. Become.

It is preferable that the sheet-like member and the member to be joined constituting the laminate have a main component of a metal selected from aluminum, copper, nickel and stainless steel. Here, using a metal selected from these metals as the main component means that a pure metal of these metals and an alloy containing these metals as the main component are used for the sheet-shaped member and the member to be joined.

The battery of the present invention has an electrode body having a structure in which an uncoated portion of an electrode plate is coated with an electrode active material, and a current extraction terminal ultrasonically bonded to the uncoated portion of the electrode body. Wherein the current extraction terminal has a projection on the joint surface with the electrode body. Providing the current extraction terminal with a projection on the joint surface with the electrode body can provide a battery in which the electrode body and the current extraction terminal are joined by an ultrasonic bonding method. Also, the battery of the present invention
Any of a primary battery and a secondary battery may be used.

The electrode body is preferably formed by laminating or winding electrode plates. That is, in the battery of the present invention, the electrode body is preferably a laminated electrode body in which electrode plates are stacked or a wound electrode body in which electrode plates are wound.

The projection is preferably formed in a conical shape.

It is preferable that the projection has substantially the same height as the thickness of the joined electrode body. That is, since the protrusion has the same height as the thickness of the electrode body, the electrode body and the current extraction terminal are sufficiently bonded.

It is preferable that the electrode-uncoated portion of the electrode plate and the terminal for taking out current mainly contain a metal selected from aluminum, copper, nickel and stainless steel. That is, materials used for ordinary batteries can be used for the electrode plate and the current extraction terminal.

[0027] In the bonding method of the laminate of the present invention, it is preferable to apply ultrasonic vibration using an ultrasonic welding machine. That is, the laminate and the member to be joined can be integrally joined by using a conventional ultrasonic welding machine.

In the method for bonding laminates of the present invention, it is preferable to apply ultrasonic vibration via a buffer plate when applying ultrasonic vibration. By arranging this buffer plate, direct damage to the laminate is reduced. That is, when the ultrasonic vibration is applied to the laminated body without disposing the buffer plate, the horn of the ultrasonic welding machine that applies the ultrasonic vibration digs in, and excessive stress is applied to the laminated body, and the sheet forming the laminated body Cutting occurs in the sheet-like member, and variations occur in the bonding between the layers of the sheet-like member constituting the laminate, and the welding quality becomes unstable. Here, aluminum, copper,
It is preferable to use a member made of nickel, stainless steel, or the like. That is, since the buffer plate is made of the same material as or can be joined to the laminate, the buffer plate and the laminate can be integrally joined to form a structure that forms a part of the connection portion.

[0029] The method for bonding a laminate of the present invention is preferably used in a bonding method for bonding a current extraction terminal to an electrode plate in an electrode body used for a secondary battery or the like. That is, the electrode plate can be joined as a sheet-like member, and the current extraction terminal can be joined as a member to be joined by ultrasonic vibration.

Here, when the current extraction terminal is joined to the electrode plate laminate using the laminate joining method of the present invention, it is preferable that the active material is not applied to the joint.

When the bonding method of the laminate of the present invention is used to connect the electrode body and the current extraction terminal, the bonding area between the electrode body and the extraction terminal can be increased, so that a large current can be extracted from the electrode plate laminate. Will be able to For this reason, the battery having the electrode body using the bonding method of the present invention,
Battery performance is improved.

[0032]

The present invention will be described below with reference to examples.

(Examples) As an example, a wound electrode body used for a prismatic battery, a current extracting terminal for extracting current from the electrode assembly,
Was joined. The wound electrode body 1 and the current extraction terminal 2
1 and 2 are shown in FIGS. FIG. 1 is a diagram showing the joined body from the direction in which the current extraction terminal 2 of the wound electrode body 1 is not joined, and FIG. 2 is a view showing the joined body from the axial direction of the wound electrode body 1.

As shown in FIG. 3, the wound electrode body 1 is an electrode body formed by winding an electrode plate composed of a positive electrode plate 11 and a negative electrode plate 12 with a separator interposed therebetween. Here, the positive electrode plate 11 is provided with a sheet-like positive electrode having a 15 μm thick aluminum sheet provided with a positive electrode active material on the surface thereof, and the negative electrode plate 12 is provided with a negative electrode active material provided on a 10 μm thick copper sheet surface. The obtained sheet-shaped negative electrode was used. In addition,
Hereinafter, this embodiment will be described using a specific example of the positive electrode.

In the wound electrode body 1, the joining portion to which the current extraction terminal 2 is joined has an uncoated portion where the active material that causes an electrode reaction on the electrode plate in the thickness direction is not applied. The positive electrode sheet is formed so that the aluminum sheet is exposed. Therefore, at the joint, 48 aluminum sheets are laminated, and the thickness is 0.7 mm.

The joint is provided in the circumferential direction of the spirally wound electrode body 1. Specifically, when the wound electrode body 1 is formed, as shown in FIG. 3, the positive electrode plate 11 and the negative electrode plate 12 are wound while being shifted from each other in the axial direction, and protruded from the end surfaces of each other. The portions are not coated with active material 111, 121
By doing so, a joint is formed.

As shown in FIG. 4, the current extraction terminal 2 has a joint surface 2 with a wound electrode body having one flat end.
1 is a rod-shaped member having a semicircular cross section, and further, a projection 22 is formed on the joint surface 21. Also, in this current extraction terminal 2, the joining surface 2
The other end that does not become 1 becomes an external terminal when the battery is assembled. Here, the current extraction terminal 2 is formed of aluminum on the positive electrode side and copper on the negative electrode side. The protrusion 2 formed on the joint surface 21
2 has a bottom side of 1.4 mm and a protrusion height of 0.7 m
It is provided to have a square pyramid shape of m. In addition,
The two protrusions 22 are provided on the joining surface 21 of the current extraction terminal 21 in the axial direction.

The spirally wound electrode body 1 and the current extracting terminal 2 are joined together such that the projection 22 of the current extracting terminal 2 abuts on the joint of the spirally wound electrode body 1 to apply ultrasonic vibration. Made by granting.

Here, the joining process in this ultrasonic joining is shown in FIG.

The application of the ultrasonic vibration was performed by using an ultrasonic welding machine using an ordinary ultrasonic bonding method. In the ultrasonic bonding, first, the current extracting terminal 2 is arranged on the anvil 71 of the ultrasonic welding machine so that the projection 22 projects vertically upward, and the current extracting terminal 2 is connected to the wound electrode body 1. The joining portion of the wound electrode body 1 was overlapped on the joining surface 21. Subsequently, the wound electrode body 1 and the current extraction terminal 2 were overlapped with each other, and a buffer plate 4 made of an aluminum plate having a thickness of 0.3 mm was further arranged. Ultrasonic vibration was applied by a horn 72 of an ultrasonic welding machine in a state where the current extracting terminal 2, the wound electrode body 1, and the buffer plate 4 were overlapped. Here, the vibration condition is that the amplitude is 42 μm.
And the vibration time was 3 seconds.

In the ultrasonic bonding, the horn 72 of the ultrasonic welding machine is vibrated in a state where the current extraction terminal 2 on the anvil 71 and the buffer plate 4 are arranged on the spirally wound electrode body 1, and the vibration is applied for a predetermined time. , Repeated.

At this time, by applying the vibration,
At the apex 23 of the projection 22, the pressing force is increased due to the reduced contact area with the spirally wound electrode body 1, so that the electrode plate and the current extraction terminal 2 constituting the spirally wound electrode body 1 are formed. The oxide film formed on the surface is removed, and a clean aluminum surface appears. The movement and diffusion of atoms occur on the clean surface. By this movement and diffusion, the electrode plates and the wound electrode body 1 and the current extraction terminal 2 are joined.

(Evaluation) The evaluation of the bonding between the wound electrode body 1 and the current extraction terminal 2 in this embodiment was performed by observing the appearance and the cross section at the bonding portion. FIGS. 6 and 7 show photographs of the appearance and the cross section.

As shown in FIGS. 6 and 7, the junction between the wound electrode body 1 and the current extraction terminal 2 in this embodiment is broken and broken by the electrode plate and the buffer plate 4 constituting the wound electrode body 1. It was found that no extra stress was applied to the electrode plate when ultrasonic vibration was applied. Furthermore, it was found that no floating or peeling was observed at the respective interfaces of the current extraction terminal 2, the electrode plate, and the buffer plate 4 due to insufficient bonding, and the solid-phase bonding was performed integrally.

(Square Battery) In this example, a square battery was manufactured using the wound electrode body 1 to which the current extraction terminal 2 was joined. This prismatic battery is shown in FIG. In this prismatic battery, the spirally wound electrode body 1 to which the extraction terminal 2 was joined was inserted into the prismatic battery container 3 together with the electrolytic solution, and fixed, whereby a prismatic battery was obtained. The prismatic battery has a current extraction terminal 2 joined to a wound electrode body 1.
The other end, which is not joined, protrudes from the rectangular battery case 3 and serves as an external terminal of the battery.

The active material used in this prismatic battery is as follows:
It is used for ordinary batteries, lithium manganese oxide for the positive electrode active material, carbon for the negative electrode active material,
A polyethylene sheet was used as the separator.

(Comparative Example) As a comparative example of the present invention, ultrasonic bonding was performed between a current extraction terminal having no projection on the bonding surface and an electrode body.

In this comparative example, ultrasonic bonding was performed under the same conditions as in the example except that a current extraction terminal having no protrusion at the bonding portion was used. FIG. 9 shows the joining process in this ultrasonic joining.

With the current extraction terminal 2 on the anvil 71 and the buffer plate 4 arranged on the wound electrode body 1, the horn 72 of the ultrasonic welding machine is vibrated, and this is repeated.

When the bonding state in this comparative example was evaluated in the same manner as in the example, voids were observed between the electrode plates constituting the wound electrode body, and a completely integrated bonding state could not be obtained. Was.

Further, in this comparative example, in order to completely join the electrode plates in the wound electrode body, ultrasonic joining was performed with the amplitude increased to 50 μm. In the joined body having the amplitude of 50 μm, the electrode plates constituting the joined portion of the wound electrode body were integrated with each other. Some of them were broken.

For this reason, according to the bonding method of this embodiment, the provision of the projections can reduce the energy of the amplitude required at the time of ultrasonic bonding, and can connect the current extraction terminal without applying stress to the electrode plate. can do.

[0053]

According to the method of joining a laminate of the present invention, a projection is provided at a portion where the member to be joined overlaps the laminate.
Since bonding can be performed with a lower vibration output than before, it is possible to prevent an excessive stress from being applied to the sheet-like members constituting the laminate. For this reason, it is useful as a joining method for joining the laminate and the member to be joined.

[Brief description of the drawings]

FIG. 1 is a diagram of a joined body of a wound electrode body and a current extraction terminal according to an embodiment.

FIG. 2 is a view of a joined body of a wound electrode body and a current extraction terminal according to an embodiment.

FIG. 3 is a diagram of a spirally wound electrode body according to an embodiment.

FIG. 4 is a diagram of a current extraction terminal according to the embodiment.

FIG. 5 is a view showing a joining process of the wound electrode body and the current extraction terminal of the example.

FIG. 6 is a photograph showing the appearance of a joint in a joined body of a wound electrode body and a current extraction terminal according to an example.

FIG. 7 is a photograph showing a cross section of a joint in a joined body of a wound electrode body and a current extraction terminal according to an example.

FIG. 8 is a view showing a prismatic battery using the joined body of the example.

FIG. 9 is a view showing a joining process of a wound electrode body and a current extraction terminal of a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Wound electrode body 11 ... Positive electrode plate 111 ... Positive electrode active material uncoated part 12 ... Negative electrode plate 121 ... Negative electrode active material non-coated part 13 ... Separator 2 ... Current extraction terminal 21 ... Joint surface 22 ... Projection 3 ... Square type Battery container 4… buffer plate 71… anvil 72… horn

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor: Mamoru Shimoda 1-1-1, Showa-cho, Kariya-shi, Aichi Prefecture Inside Denso Corporation (72) Inventor: Tomoyasu Takeuchi 1-1-1, Showa-cho, Kariya-shi, Aichi Prefecture Denso Corporation (72) Inventor Yoshihiko Matsuzaka 1-1-1, Showa-cho, Kariya-shi, Aichi Prefecture Inside Denso Corporation (72) Inventor Koji Fujiki 1-1-1, Showa-cho, Kariya-shi, Aichi Prefecture Inside Denso Corporation (72) Inventor Ko Nozaki 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Goro Watanabe 41-Cho, Yokomichi, Nagakute-cho, Aichi-gun, Aichi F-term in Toyota Central Research Laboratory Co., Ltd. 4E067 AA03 AA05 AA07 AA09 BF00 BF04 EC02 5H022 AA09 BB17 CC08 CC16 CC22

Claims (10)

[Claims] An ultrasonic vibration is applied to a laminate having a structure in which sheet members are laminated, and a member to be joined superimposed on the laminate, so that the sheet members of the laminate and the What is claimed is: 1. A method for joining a laminate, comprising joining a laminate and a member to be joined, wherein the member to be joined has a protrusion projecting from a portion where the laminate is overlapped with the laminate, wherein the protrusion is the laminate. A method for joining laminated bodies, wherein ultrasonic vibration is applied in a state of pressing the laminate. 2. The method according to claim 1, wherein the laminate is formed by laminating or winding the sheet-shaped members. 3. The method according to claim 1, wherein the protrusion is formed in a conical shape. 4. The bonding method according to claim 1, wherein the protrusion has a height substantially equal to a thickness of the stacked body in an overlapped portion. 5. The bonding method for a laminate according to claim 1, wherein the sheet-like member and the member to be joined constituting the laminate mainly include a metal selected from aluminum, copper, nickel, and stainless steel. 6. A battery comprising: an electrode body having a structure in which an uncoated portion of an electrode active material of an electrode plate is laminated; and a current extracting terminal ultrasonically bonded to the uncoated portion of the electrode body. The battery according to claim 1, wherein the current extraction terminal has a projection on a joint surface with the electrode body. 7. The battery according to claim 6, wherein the electrode body is formed by laminating or winding the electrode plates. 8. The battery according to claim 6, wherein the protrusion is formed in a conical shape. 9. The battery according to claim 6, wherein the protrusion has substantially the same height as the thickness of the joined electrode body. 10. The battery according to claim 6, wherein the electrode active material-uncoated portion of the electrode plate and the current extraction terminal mainly include a metal selected from aluminum, copper, nickel, and stainless steel.