JP4543310B2 - Electrode bonding method and electrode assembly - Google Patents

Description

  The present invention relates to a method for joining an electrode structure member to an electrode terminal protruding from a battery by ultrasonic welding, and more particularly to a method for joining electrodes having a low risk of adversely affecting the battery. Furthermore, the present invention relates to a high-quality and low-cost electrode assembly bonded by adopting this electrode bonding method.

  In recent years, non-aqueous secondary batteries (especially lithium secondary batteries) having a high energy density have been attracting attention as the weight and size of electrical products have been reduced. In addition, due to environmental problems, electric vehicles and hybrid vehicles using electric power as a part of power are actively put into practical use, and high-performance secondary batteries are required for storing electric power.

  In order to mount a secondary battery on a vehicle, a plurality of single cells (cells) are connected in series with a bus bar or the like to form an assembled battery (see, for example, Patent Document 1). Since the electrode terminal reaches the inside of the battery and contacts the electrolytic solution, it is desirable that the electrode terminal is made of an appropriate material (eg, positive electrode: aluminum, negative electrode: copper, etc.). Therefore, the electrode terminal and the bus bar are joined between dissimilar metals. Conventionally, in the battery assembly, a method of fastening and connecting the electrode terminal for extracting energy from the unit cell and the bus bar with a screw or the like is the mainstream. However, as the number of cells constituting the assembled battery increases, the number of fastening portions increases and the electrical resistance at the connection portion increases, so that the performance degradation of the entire assembled battery becomes a problem. In addition, fastening with screws is in a situation where efficiency is lowered in terms of productivity.

Currently, there is a joining method using ultrasonic welding as a means for connecting a plurality of single cells. In general ultrasonic welding, planar portions to be abutted are formed between members to be joined, and the respective planar portions are brought into contact with each other while being pressed to perform joining. In this case, in order to form the plane part which is a joining surface, restrictions of a product shape may arise. Moreover, since it is necessary to process an electrode terminal etc., component cost becomes high.
JP 2003-115285 A

  This invention is made | formed in view of the said situation, and makes it the subject which should be solved to provide the joining method of the electrode which can perform joining of an electrode terminal and an electrode structure member simply by ultrasonic welding. It is another object of the present invention to provide an electrode assembly that can be obtained with stable quality and low cost.

  The electrode joining method of the present invention includes an electrode terminal electrically connected to the inside and outside of a battery case and fixed to the battery, and an electrode structure member used by being joined to an end of the electrode terminal protruding outside the battery. Are joined by ultrasonic welding.

  In order to solve the above problems, the present inventors have conducted intensive studies. As a result, it has been found that it is necessary to apply a sufficient load between the electrode terminal and the electrode structural member in order to sufficiently bond the electrode terminal and the electrode structure member without providing a flat portion on the bonding surface. However, if an excessively large load is applied to the electrode terminal, there is a possibility that an important component (such as an electrode body) inside the battery is adversely affected.

Accordingly, the inventors have conceived that the load of the ultrasonic horn is supported by providing a locking portion on the electrode terminal and locking the load receiving locking means to the locking portion, and the following invention has been completed. That is, the electrode terminal has a locking portion that can lock the load receiving locking means on the side surface,
A step of abutting and pressurizing an ultrasonic horn against the electrode terminal and / or the electrode structure member while engaging the load receiving engagement means with the engagement portion and joining the two together. Features.

  That is, by receiving the load applied by the ultrasonic horn by the load receiving and locking means, the influence on the battery or the like can be reduced, and stable high quality can be ensured. In addition, since a sufficient bonding strength can be ensured without previously forming the flat portion, cost reduction can be realized.

The electrode structure member has an end insertion hole which is a through hole into which a part or all of the end of the electrode terminal can be inserted.
The ultrasonic horn is bonded between the electrode structural member and the electrode terminal by closely contacting the inner wall of the end insertion hole while crushing part or all of the end portion in the end insertion hole. Even if the electrode terminal and the electrode structural member are made of different metals, high quality bonding can be performed.

  Here, examples of the locking portion include a through hole provided on a side surface of the electrode terminal, and examples of the load receiving locking means include a member that is inserted into and locked to the locking portion. . The electrode structure member can be exemplified by a member for electrically connecting the cells in the assembled battery.

Furthermore, the electrode assembly of the present invention that solves the above-mentioned problems is an electrode structure in which the inside and outside of the battery are electrically connected and fixed to the battery, and the electrode structure is joined to the end of the electrode terminal that protrudes outside the battery. An electrode assembly having a member,
The electrode terminal has a locking portion that can lock the load receiving locking means on the side surface,
Produced by the process of contacting and pressurizing an ultrasonic horn against the electrode terminal and / or the electrode structure member while engaging the load receiving engagement means with the engagement portion and joining the two together. It is characterized by that.

The electrode structure member has an end insertion hole which is a through hole into which a part or all of the end of the electrode terminal can be inserted.
The ultrasonic horn joins the electrode structural member and the electrode terminal by closely contacting the inner wall of the end insertion hole while crushing part or all of the end portion in the end insertion hole. It is preferable.

  Moreover, as the said latching | locking part, the through-hole provided in the side surface of the said electrode terminal is mentioned. And the said electrode structure member can illustrate the member which electrically connects between cells in an assembled battery.

  Since the electrode terminal and the electrode structure member are bonded by ultrasonic welding, the bonding can be performed reliably and reliably. Since ultrasonic welding is performed in a state where the load receiving and locking means is locked to the locking portion provided on the electrode terminal, the influence on the battery due to the load applied during ultrasonic welding can be suppressed as much as possible. Since the engaging portion provided on the electrode terminal can be easily formed by pressing or the like, the cost can be reduced.

[Electrode bonding method]
The electrode joining method of the present invention is a method of joining an electrode terminal and an electrode structure member by ultrasonic welding. The electrode terminal is a member that electrically connects the inside and outside of the battery case. The electrode terminals are joined while being fixed to the battery. This method can be suitably applied when the electrode structural member is joined in a state where the electrode terminal is fixed to the power generation element of the battery. The electrode structure member is joined to the end of the electrode terminal that protrudes outside the battery. Examples of the electrode structure member include a member such as a bus bar for electrically connecting the electrode terminals of the unit cells in an assembled battery including a plurality of unit cells. It is presumed that the bus bar is often joined to the electrode terminal after the unit cell is manufactured in the manufacturing process of the assembled battery.

  The electrode terminal has a locking portion on the side surface. The locking portion has a structure in which the load receiving locking means can be locked. Examples of the locking portion include a hole penetrating the electrode terminal or a through hole that is a notch, a concave portion in which a part of the electrode terminal is recessed, and a convex portion in which a part of the electrode terminal is protruded. The electrode terminals are preferably formed by pressing or the like, and the locking portions are also preferably formed simultaneously by pressing.

  The load receiving and locking means is a member that exerts an effect of suppressing the influence of the load on the battery by receiving the load applied to the electrode terminal by being locked to the locking portion of the electrode terminal. Ultrasonic welding is performed in a state where the load receiving locking means is locked to the locking portion. Ultrasonic welding is a process in which an ultrasonic horn is brought into contact with and pressed to join the two. When joining is performed in a state where the electrode terminal and the electrode structure member are in contact with each other, it is preferable that an ultrasonic horn is brought into contact with the electrode structure member.

  The electrode structure member may be provided with an end insertion hole which is a through hole into which a part or all of the end of the electrode terminal can be inserted, and bonding may be performed with the end of the electrode terminal inserted into the end insertion hole. it can. It is preferable to adopt such a configuration when joining between electrode terminals and electrode structural members made of different materials. In that case, it is preferable that the end portion of the electrode terminal is crushed by bringing an ultrasonic horn into contact with the end portion of the electrode terminal and is closely bonded to the inner wall of the end portion insertion hole. Although it is possible to envisage a method in which the end of the electrode terminal is pressed and simply crushed, it is possible to perform bonding more reliably by ultrasonic welding.

(Electrode assembly)
The electrode assembly of the present invention includes an electrode terminal and an electrode structure member. The two are joined by ultrasonic welding. The electrode terminal is a member that electrically connects the inside and outside of the battery, and is fixed to the battery. The electrode structure member is a member joined to an end portion of the electrode terminal protruding outside the battery. For example, in an assembled battery composed of a plurality of single cells, a member such as a bus bar that electrically connects the electrode terminals of the single cells is applicable.

  The electrode terminal has a locking portion on the side surface, and the electrode terminal and the electrode structure member are joined in a state where the load receiving locking means is locked to the locking portion. The locking portion has a structure in which the locking portion can be locked by the load receiving locking means. Examples of the locking portion include a through hole, a concave portion in which a part of the electrode terminal is recessed, and a convex portion in which a part of the electrode terminal is protruded. The electrode terminal is preferably formed by pressing or the like. Bonding between the electrode terminal and the electrode structure member is performed in a process in which an ultrasonic horn is contacted and pressed. When joining is performed in a state where the electrode terminal and the electrode structure member are in contact with each other, it is preferable that an ultrasonic horn is brought into contact with the electrode structure member.

  The electrode structure member may be provided with an end insertion hole which is a through hole into which a part or all of the end of the electrode terminal can be inserted, and bonding may be performed with the end of the electrode terminal inserted into the end insertion hole. it can. In that case, the end of the electrode terminal is crushed by bringing an ultrasonic horn into contact with the end of the electrode terminal, and is tightly bonded to the inner wall of the end insertion hole.

  The electrode joining method and electrode assembly of the present invention will be described below in detail based on examples. In the following description, as shown in FIG. 1, as an electrode structure member for electrically connecting the electrode terminals 5 and 6 of the unit cells A to F in the assembled battery composed of the six unit cells A to F. As a method of joining the bus bar 7 to the electrode terminals 5 and 6, the electrode joining method of this embodiment is adopted. The joined electrode terminals 5 and 6 and the bus bar 7 constitute the electrode assembly of the present embodiment. The electrode assembly of this embodiment is composed of electrode terminals 5 and 6 and a bus bar 7.

  The bus bar 7 is made of an aluminum material, and electrically connects the positive electrode terminal 5 made of an aluminum material and the negative electrode terminal 6 made of a copper material between adjacent cells A to F. ing. The ends of the electrode terminals 5 and 6 are joined to the bus bar 7 by ultrasonic welding.

  As shown in FIG. 2, the electrode terminals 5 and 6 are formed with through holes 5a and 6a as end insertion holes for the locking portions. A clamp jig 10 serving as a load receiving and locking means having a projection 11 that is locked to the through hole 5a is locked to the through hole 5a. In a state where the electrode terminal 5 is held by the clamp jig 11 from the opposite side of the clamp jig 10, the bus bar 7 is brought into contact with the end portion 5b of the electrode terminal 5, and ultrasonic waves are applied from the opposite side to the end portion 5b. Ultrasonic welding is performed with the horn 13. The surface where the clamp jigs 10 and 12 are in contact with the electrode terminal 5 is knurled to make it difficult to slide. The bus bar 7 is held in guides 10 b and 12 b provided on the clamp jigs 10 and 12. A gap H is provided between the upper surfaces of the clamping jigs 10 and 11 and the bus bar 7, and the end 5b of the electrode terminal 5 is melted and welded to the bus bar 7 by a length corresponding to the gap H (FIG. 3). .

  The load applied by the ultrasonic horn 13 is received by the projection 11 of the clamp jig 10 through the upper surface 5c of the through hole 5a, and the influence on the cells A to F can be suppressed. Similarly to the electrode terminal 5, the electrode terminal 6 is joined by ultrasonic welding in a state where the projection 11 of the clamp jig 10 is locked in the through hole 6 a (FIG. 4). FIG. 5 shows a cross-sectional photograph of the joint portion between the end portion 5b and the bus bar 7. As is apparent from FIG. 5, extremely good bonding was realized to such an extent that the bonding surface between the end 5 b and the bus bar 7 was not known.

  As shown in FIG. 6, the electrode joining method of this embodiment is the same as that of Embodiment 1 except that an end insertion hole 7 a is provided in the bus bar 7 and the end 5 b of the electrode terminal 5 is inserted. Is almost the same. The end 5 b passes through the end insertion hole 7 a of the bus bar 7 and protrudes by H. There is no gap between the clamping jigs 10 and 12 and the bus bar 7 as in the first embodiment, and they are in close contact with each other.

  In a state where the electrode terminal 5 is held between the clamp jigs 10 and 11, the end portion 5b is crushed by bringing the ultrasonic horn 13 into contact with and pressurizing the end portion 5b. When the end 5b is crushed in the end insertion hole 7a, the vicinity of the end 5b of the electrode terminal 5 is brought into close contact with the inner wall of the end insertion hole 7a (FIG. 7).

  The load applied by the ultrasonic horn 13 is received by the projection 11 of the clamp jig 10 through the upper surface 5c of the through hole 5a, and the influence on the cells A to F can be suppressed. Similarly to the electrode terminal 5, the electrode terminal 6 is joined by ultrasonic welding in a state where the projection 11 of the clamp jig 10 is locked in the through hole 6 a (FIG. 8).

  The shape of the end portion of the electrode terminal can be a part of the end portion (FIG. 10) or a tapered shape (FIG. 11) as shown in FIGS. By adopting such an end shape, the inserted portion is easily crushed and can be joined easily. A cross-sectional photograph of the joint portion between the end 6b and the bus bar 7 is shown in FIG. The end 6b is made of copper, and the bus bar 7 is made of aluminum. As can be seen from FIG. 12, the joining surface between the end portion 6b and the bus bar 7 can be seen, but the joining surface is in close contact with no gap, and extremely good joining can be realized.

  In both Embodiments 1 and 2 described above, the electrode terminal and the bus bar can be joined on the atomic level, so that the electrical resistance at the joint is reduced and reliable and reliable joining can be realized. Here, since the pressure applied at the time of ultrasonic welding can be received by the clamp jig (load receiving / holding means), the pressure can be applied by the ultrasonic horn without considering the influence on the battery. As a result, more reliable joining can be realized.

It is a perspective view which shows the external appearance of the assembled battery of an Example. It is the schematic which shows the mode of joining between the electrode terminal and bus bar in Example 1. FIG. It is the schematic which shows the mode of joining between the electrode terminal and bus bar in Example 1. FIG. It is the schematic which shows the mode of joining between the electrode terminal and bus bar in Example 1. FIG. 2 is a cross-sectional photograph between an electrode terminal and a bus bar joined by the method of Example 1. FIG. It is the schematic which shows the mode of joining between the electrode terminal and bus bar in Example 2. FIG. It is the schematic which shows the mode of joining between the electrode terminal and bus bar in Example 2. FIG. It is the schematic which shows the mode of joining between the electrode terminal and bus bar in Example 2. FIG. 6 is a schematic perspective view showing the shape of an end portion of an electrode terminal that can be employed in Example 2. FIG. 6 is a schematic perspective view showing the shape of an end portion of an electrode terminal that can be employed in Example 2. FIG. 6 is a schematic perspective view showing the shape of an end portion of an electrode terminal that can be employed in Example 2. FIG. It is a cross-sectional photograph between the electrode terminal joined by the method of Example 2 and a bus bar.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Case 2 ... Cover 3 ... Smoke exhaust port 4 ... Electrolyte injection port 5 ... Positive electrode terminal 5a ... Through-hole (locking part) 5b ... End part 5c ... Upper surface 6 ... Negative electrode terminal 6a ... Through-hole (locking part) 6b ... End 6c ... Upper surface 7 ... Bus bar 7a ... Joining part 7b ... Joining part 8, 9 ... Bus bar (for extracting current)
A to F: Cell 10: Clamping jig (load receiving locking means) 10b: Guide 11 ... Projection 12 ... Clamping jig 12b ... Guide 13 ... Ultrasonic horn 14, 15 ... Joint

Claims (8)

Method of joining by ultrasonic welding the electrode terminal that is electrically connected inside and outside the battery case and fixed to the battery, and the electrode structure member that is used by being joined to the end of the electrode terminal protruding outside the battery Because
The electrode terminal has a locking portion that can lock the load receiving locking means on the side surface,
A step of abutting and pressurizing an ultrasonic horn against the electrode terminal and / or the electrode structure member while engaging the load receiving engagement means with the engagement portion and joining the two together. A method for joining electrodes. The electrode structure member has an end insertion hole that is a through hole into which a part or all of the end of the electrode terminal can be inserted;
The ultrasonic horn is bonded between the electrode structural member and the electrode terminal by closely contacting the inner wall of the end insertion hole while crushing part or all of the end portion in the end insertion hole. 2. The method for joining electrodes according to 1. The locking portion is a through hole provided in a side surface of the electrode terminal,
The electrode joining method according to claim 1 or 2, wherein the load receiving and locking means is a member inserted and locked in the locking portion.   The electrode joining method according to any one of claims 1 to 3, wherein the electrode structure member is a member for electrically connecting the cells in the assembled battery. An electrode assembly comprising an electrode terminal electrically connected to the inside and outside of the battery and fixed to the battery, and an electrode structure member joined to an end of the electrode terminal protruding outside the battery,
The electrode terminal has a locking portion that can lock the load receiving locking means on the side surface,
Produced by the process of contacting and pressurizing an ultrasonic horn against the electrode terminal and / or the electrode structure member while engaging the load receiving engagement means with the engagement portion and joining the two together. An electrode assembly characterized by that. The electrode structure member has an end insertion hole that is a through hole into which a part or all of the end of the electrode terminal can be inserted;
The ultrasonic horn joins the electrode structural member and the electrode terminal by closely contacting the inner wall of the end insertion hole while crushing part or all of the end portion in the end insertion hole. The electrode assembly according to claim 5.   The electrode assembly according to claim 5 or 6, wherein the locking portion is a through hole provided in a side surface of the electrode terminal.   The electrode assembly according to any one of claims 5 to 7, wherein the electrode structure member is a member for electrically connecting the cells in the assembled battery.

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