Resistance-welding method and resistance-welding apparatus for terminals for electrode connection of battery

Abstract

To provide a resistance-welding method and apparatus for terminals for electrode connection of a battery in which a positive electrode and a negative electrode of the battery can be resistance-welded to respective terminals for electrode connection on the same side, miniaturization and effective cooling can be achieved when using multiple batteries, and the degree of freedom of the configuration thereof can be improved.SOLUTION: A positive electrode 3 of a can-type battery 1, a negative electrode 2 of a peripheral portion of the can top and respective plate-like terminals 7, 8 for electrode connection are resistance-welded from the same direction and electrically-connected to each other. On the terminal 7 for negative electrode connection, a pair of projections 14, 14 extending in the radial direction and adjacently provided in the circumferential direction are formed at welding points that face each other in the circumferential direction of the peripheral portion 2. Slits 15 that extend in a direction intersecting the radial direction are formed at the tip position in the radial direction of the projections 14, 14.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a resistance welding method and apparatus for resistance welding a battery electrode connection terminal, which electrically connects a plurality of batteries together by resistance welding the battery and the electrode connection terminal. [Background technology]

[0002] Generally, there is known a battery pack in which a plurality of batteries are electrically connected to each other by resistance welding a can-shaped battery such as a cylindrical lithium-ion battery to a plate-shaped electrode connection terminal (tab) (for example, Patent Document 1). Here, resistance welding refers to a method in which a pair of welding electrodes is brought into contact with a metal material, and a large current is passed for a short period of time while applying pressure, to utilize the resistance heat of the metal to generate a nugget (alloy layer) and fuse the connection.

[0003] In recent years, batteries for electric vehicles (EVs), electric bicycles (E-bikes), and other devices require higher output due to the use of multiple cells, and there has been a trend for electrode connection terminals to be transitioned from nickel (Ni) to copper (Cu) or copper alloys, which have higher electrical conductivity (lower electrical resistance) and higher thermal conductivity. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-119116 A Summary of the Invention [Problem to be solved by the invention]

[0005] When multiple batteries are used, the batteries themselves generate heat during charging and discharging, and air or water cooling is used to suppress this heat generation. However, because the spaces between the batteries are covered with separator cases and the bottoms of the batteries are hidden by electrode connection terminals (tabs), the batteries cannot be cooled directly, which means the cooling equipment becomes larger and effective cooling can be difficult.

[0006] In addition, conventionally, it was necessary to weld electrode connection terminals to each of the positive electrodes (convex part of the top lid) and negative electrodes (bottom of the can) of multiple batteries, which meant that both the top and bottom sides of each can-shaped battery had to be used for connection, limiting the freedom of configuration.

[0007] In this case, it is assumed that the negative electrode is connected to the upper side (positive electrode side) of the can-shaped battery by resistance welding a negative electrode connecting terminal to the negative electrode on the rim (shoulder of the battery) 2 of the upper part of the can in Fig. 1(A). However, as shown in Fig. 1(B), a sealing packing 6 is provided directly below the rim (shoulder of the battery) 2, and if the negative electrode connecting terminal is resistance welded to the rim 2, there is a concern that the heat generated by welding may affect the sealing packing 6, making this difficult to realize.

[0008] The present invention aims to solve the above problems and provide a method and apparatus for resistance welding of battery electrode connection terminals, which enables the positive and negative electrodes of a battery to be resistance welded to each electrode connection terminal on the same side, enables compactness and effective cooling when using multiple batteries, and improves the freedom of configuration. [Means for solving the problem]

[0009] In order to achieve the above object, the present invention provides a resistance welding method and apparatus for battery electrode connection terminals, in which a positive electrode on a convex portion of an upper lid of a can-shaped battery and a plate-shaped positive electrode connection terminal, and a negative electrode on a peripheral portion of the upper portion of the can and a plate-shaped negative electrode connection terminal are brought into contact with an outer surface of each connection terminal opposite the battery from the same direction by a pair of welding electrodes, and the welding electrodes are energized for resistance welding, so that the positive and negative electrodes of the battery are electrically connected to each connection terminal, At least a pair of radially extending projections are formed on the negative electrode connecting terminal and are arranged adjacent to each other in the circumferential direction at positions facing each other in the circumferential direction of the peripheral edge portion, and a welding current is induced and concentrated in the projections, thereby suppressing welding energy; A slit extending in a direction intersecting the radial direction is formed at the radial tip position of the projection, thereby suppressing the welding current and reducing heat generation.

[0010] According to this configuration, the positive and negative electrodes of the can-shaped battery are resistance welded to each connection terminal from the same direction, and at least a pair of projections are formed on the negative electrode connection terminal, arranged adjacent to each other in circumferentially opposing positions on the peripheral edge, so that the welding current is induced and concentrated in the projections, thereby suppressing the welding energy, and a slit extending in a direction intersecting the radial direction is formed at the radial tip position of the projection, thereby suppressing the welding current and suppressing heat generation.

[0011] This shortens the distance over which the welding current flows between a pair of projections arranged adjacent to each other in the circumferential direction, and the slits suppress the welding current to suppress heat generation and also make the welding current less likely to flow, thereby suppressing heat generation at the periphery (shoulder of the battery) and reducing the thermal impact on the battery sealing gasket directly below. Also, since the positive and negative electrodes of the battery and each electrode connection terminal are electrically connected on the same side without using the bottom of the can for electrical connection, each can bottom can be used for direct cooling, allowing for compact and effective cooling when using multiple batteries, and electrical connection on the same side is possible, improving the degree of freedom in the configuration.

[0012] Preferably, a pair of projections are formed adjacent to each other in the circumferential direction at welding points on the peripheral edge portion that face each other in the circumferential direction, and the negative electrode connecting terminal and the negative electrode are resistance-welded to each other in sequence via the projections by a pair of welding electrodes at each welding point. In this case, the number of projections becomes four, and the welding strength between the negative electrode and the negative electrode connecting terminal can be increased.

[0013] Preferably, each connection terminal is made of plate-like copper or copper alloy, which has high electrical and thermal conductivity, and therefore, when multiple batteries are used, a higher output can be obtained.

[0014] Preferably, each battery electrically connected by the resistance welding device can be directly cooled by a coolant at the bottom of the can, making it easier to cool a plurality of batteries. Effect of the Invention

[0015] In the present invention, the distance through which the welding current flows between a pair of projections arranged adjacent to each other in the circumferential direction in the negative electrode connection terminal is shortened, and the welding current is suppressed by the slits to suppress heat generation and to make the welding current less likely to flow, which combine to suppress heat generation at the periphery (shoulder of the battery) and reduce the thermal impact on the battery sealing packing directly below. Also, since the positive and negative electrodes of the battery and each connection terminal are electrically connected without using the can bottom side for electrical connection, the can bottoms can be used directly for cooling, allowing for compactness and effective cooling when multiple batteries are used, and electrical connection is possible only on the positive electrode side, improving the degree of freedom in the configuration. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1A is a perspective view showing an example of a can-shaped battery used in a resistance welding device for battery electrode connection terminals in the present invention, and FIG. [Diagram 2] 1 is a front view showing a resistance welding device for a negative electrode and a negative electrode connecting terminal of a battery according to an embodiment of the present invention. [Diagram 3] 1A is a front view showing an apparatus for resistance welding a positive electrode and a positive electrode connecting terminal of a battery according to one embodiment of the present invention, and FIG. 1B is a plan view of the positive electrode connecting terminal. [Figure 4] 1A is a plan view of a negative electrode connecting terminal, FIG. 1B is a side view thereof, and FIG. 1C is a partial longitudinal sectional view of FIG. [Diagram 5] 2A is a perspective view of a negative electrode connecting terminal, and FIG. 2B is a schematic perspective view showing a resistance welding device for connecting a negative electrode of a battery to the negative electrode connecting terminal. [Figure 6] 4 is a plan view showing the operation of a resistance welding device for a negative electrode of a battery and a negative electrode connecting terminal in the present invention. FIG. [Figure 7] 1A is a perspective view of another example of a negative electrode connecting terminal in the present invention, and FIG. 1B is a schematic perspective view showing another example of an apparatus for resistance welding a battery negative electrode and a negative electrode connecting terminal in the present invention. [Figure 8]13 is a plan view showing the operation of another example of a resistance welding device for a negative electrode of a battery and a negative electrode connecting terminal. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1(A) is a perspective view showing an example of a can-shaped battery 1 used in a resistance welding device for a battery electrode connection terminal according to one embodiment of the present invention, and FIG. 1(B) is a partial vertical cross-sectional view thereof. As shown in FIG. 1(A), the upper lid protrusion (top cap) 3 of this battery 1 is the positive electrode (+), and the peripheral portion (shoulder of the battery) 2 at the top of the can and the can bottom 5 are the negative electrode (-). As shown in FIG. 1(B), the can bottom 5 and the peripheral portion 2 are connected via the exterior can 4 of the battery 1 to form the negative electrode (-). A sealing packing 6 is provided between the positive electrode (+) and the negative electrode (-). In the present invention, the negative electrode (-) of the peripheral portion 2 is resistance welded.

[0018] The can-shaped battery 1 is, for example, a cylindrical lithium ion battery, and the plate-shaped negative and positive electrode connecting terminals 7, 8 are made of, for example, copper or a copper alloy. Nickel, which has a lower electrical conductivity than copper, may also be used.

[0019] Fig. 2 is a front view showing a state in which a negative electrode 2 and a negative electrode connecting terminal 7 are welded in a resistance welding device for a battery electrode connecting terminal according to one embodiment of the present invention. Fig. 3(A) is a front view showing a state in which a positive electrode 3 and a positive electrode connecting terminal 8 are welded in the same device.

[0020] 2, a pair of welding electrodes 10, 11 are supplied with power from a welding power source (not shown), and the pair of welding electrodes 10, 11 are brought into contact with, for example, a pair of welding points that face circumferentially on the peripheral portion (negative electrode) 2 of the battery 1 (separated radially, in this example, 180° apart), on the outer surface of the negative electrode connecting terminal 7 opposite the negative electrode 2 of the battery 1, and electricity is passed between the welding electrodes 10, 11, causing a welding current A to flow. The negative electrode connecting terminal 7 is, for example, hollow in shape to correspond to the positive electrode 3 of the battery 1.

[0021] The welding current A is forcibly induced to pass through a projection 14 described later, whereby a nugget (alloy layer) N is formed between the negative electrode connecting terminal 7 and the negative electrode 2 of the battery 1 due to resistance heating, and the negative electrode 2 of the battery 1 is resistance welded to the negative electrode connecting terminal 7.

[0022] As shown in FIG. 3(A), power is supplied to a pair of welding electrodes 10, 11 from a welding power source (not shown), the pair of welding electrodes 10, 11 straddles slit 22 and contacts the outer surface of positive electrode connecting terminal 8 opposite the positive electrode 3 of battery 1, electricity is passed between the welding electrodes 10, 11, and welding current A1 flows.

[0023] As shown in FIG. 3(B), the positive electrode connecting terminal 8 has a total of four projections 21, for example two projections 21, formed at each welding point of the positive electrode 3 of each battery 1 with slits 22 therebetween.

[0024] The welding current A1 in Figure 3 is forcibly induced to pass through this projection 21, whereby a nugget (alloy layer) N is formed between the positive electrode connecting terminal 8 and the positive electrode 3 of the battery 1 due to resistance heating, and the positive electrode 3 of the battery 1 is resistance welded to the positive electrode connecting terminal 8.

[0025] In this example, the negative electrode (-) of the peripheral portion (shoulder of the battery) 2 and the plate-shaped terminal (tab) 7 for connecting the negative electrode, and each positive electrode (+) of the top lid protrusion 3 and the plate-shaped terminal (tab) 8 for connecting the positive electrode are resistance welded in the same welding direction, meaning that the connections of the batteries 1 can be concentrated only on the positive electrode side, making it possible to electrically connect multiple batteries 1 without using the negative electrodes (-) of each can bottom 5 for electrical connection as in the conventional case.

[0026] The negative electrode connecting terminal 7 in Fig. 2 will be described in detail with reference to Figs. 4(A) to (C). As shown in Fig. 4(A), the negative electrode connecting terminal 7 for connecting the negative electrode 2 has a pair of radially extending projections 14, 14 (Fig. 4(B)) arranged adjacent to each other in the circumferential direction in correspondence with the welding points 17, 18 facing each other in the circumferential direction of the peripheral edge portion (negative electrode) 2, and the welding current A is induced and concentrated in the projections 14 to minimize the welding energy. The pair of projections 14 has a left-right separating slit 16 for separating the projections 14, 14, as shown in Fig. 4(C). The pair of welding electrodes 10, 11 straddle the slit 16 and come into contact with each projection 14, 14.

[0027] In addition, as shown in FIG. 4(A), a slit 15 is formed in the negative electrode connecting terminal 7 at the radial tip position of the projections 14, 14, extending in a direction intersecting the radial direction, for example, perpendicular thereto, thereby suppressing the welding current A and suppressing heat generation.

[0028] Fig. 5(A) is a perspective view of a negative electrode connecting terminal 7, and (B) is a schematic perspective view showing a resistance welding device for a battery negative electrode and a negative electrode connecting terminal. As shown in Fig. 5(B), first, a pair of welding electrodes 10, 11 resistance-welds the negative electrode 2 and the negative electrode connecting terminal 7 at a first welding point 17 in Fig. 5(A) where the projections 14, 14 and the slit 15 are formed. Next, a pair of welding electrodes 10, 11 resistance-welds the negative electrode 2 and the negative electrode connecting terminal 7 at a second welding point 18 in Fig. 5(A).

[0029] FIG. 6 is a plan view showing the operation of a resistance welding device for a battery negative electrode and a negative electrode connecting terminal. At the first welding point 17, the distance through which the welding current flows between a pair of projections 14, 14 arranged adjacent to each other in the circumferential direction due to the current passing through the pair of welding electrodes 10, 11 is short, so the current path is large. At the same time, the slits 15 suppress the welding current to suppress heat generation, and make it difficult for the welding current to flow around the slits 15 to reduce the current path. These combine to suppress heat generation at the peripheral portion (shoulder of the battery) 2, and reduce the thermal effect on the battery sealing packing 6 directly below. The second welding point 18 also operates in a similar manner. In this case, the number of projections 14 becomes four, and the welding strength between the negative electrode 2 and the negative electrode connecting terminal 7 can be increased.

[0030] The welding power source used may be, for example, a high-energy type welding power source with a large-capacity capacitor that can pass a large current in a short time. This allows the sealing packing 6 (Fig. 1(B)) of the battery 1 to be safely protected even if it is directly under the welding point, thanks to the effects of the projections 14, 14 and slits 15 of the negative electrode connecting terminal 7, making it possible to safely prevent leakage.

[0031] The can bottom 5 of the battery 1 can be directly cooled by the coolant, making it possible to reduce the size and provide effective cooling. A battery pack can be formed by connecting multiple batteries 1 to multiple negative and positive electrode connecting terminals. In this case, the battery pack can be reduced in size and provided with effective cooling by the coolant provided on the can bottom side.

[0032] In this way, in the present invention, the negative electrode 2 and positive electrode 3 of the can-shaped battery 1 are resistance-welded to the respective connection terminals 7, 8 from the same direction, and a pair of projections 14, 14 arranged adjacent to each other in the circumferential direction at circumferentially opposing positions on the peripheral portion (negative electrode) 2 are formed on the negative electrode connection terminal 7, so that the welding current is induced and concentrated on the projections 14, 14, thereby suppressing the welding energy, and slits 15 extending in a direction intersecting the radial direction are formed at the radial tip positions of the projections 14, 14, thereby suppressing the welding current and suppressing heat generation.

[0033] This shortens the distance over which the welding current flows between a pair of projections 14, 14 arranged adjacent to each other in the circumferential direction in the negative electrode connecting terminal 7, and the slits 15 suppress the welding current to suppress heat generation and also make the welding current less likely to flow, thereby suppressing heat generation in the peripheral portion (shoulder of the battery) 2 and reducing the thermal impact on the battery sealing gasket 6 directly below. Also, since the negative electrode 2 and positive electrode 3 of the battery 1 and each of the electrode connecting terminals 7, 8 are electrically connected on the same side without using the can bottom side for electrical connection, using each can bottom 5 directly for cooling allows for size reduction and effective cooling when multiple batteries are used, and electrical connection is possible on the same positive electrode side, improving the degree of freedom in the configuration.

[0034] In this embodiment, two pairs of projections are provided at opposing positions on the negative electrode connecting terminal, but two or more pairs of projections may be provided.

[0035] 7(A) is a perspective view of another example of a negative electrode connecting terminal 19, and (B) is a front view showing another example of an apparatus for resistance welding the negative electrode 2 of a battery and the negative electrode connecting terminal 19. The negative electrode connecting terminal 19 is formed with a plurality of radially extending projections 14, for example, a pair of projections 14 facing each other in the circumferential direction, and a slit 15 is formed at the radial tip position of the projections 14, extending in a direction intersecting the radial direction, for example perpendicular thereto. The negative electrode connecting terminal 19 is, for example, hollow in shape in correspondence with the positive electrode 3 of the battery 1.

[0036] As shown in FIG. 7(B), a pair of welding electrodes 10, 11 are used to resistance-weld the negative electrode 2 and the negative electrode connecting terminal 19 at two circumferentially opposing welding points on the peripheral portion (shoulder of the battery) 2.

[0037] Fig. 8 is a plan view showing the operation of another example of a resistance welding device for a battery negative electrode 2 and a negative electrode connecting terminal 19. A projection 23 that concentrates a welding current at the welding point to suppress welding energy and a slit 24 that blocks the welding current from the projection 23 to suppress heat generation are formed in the negative electrode connecting terminal 19 that connects the negative electrode 2 to the peripheral portion of the upper part of the can, and the negative electrode 2 and the negative electrode connecting terminal 19 are electrically connected without the peripheral portion 2 being burned out by resistance welding. In this other example, current path 1 and current path 2 that flow through the shoulder 2 of the battery and the negative electrode connecting terminal 19 are generated, so the current path is longer than that in Fig. 6, and there is a possibility that heat generation and welding variation will be slightly higher.

[0038] The present invention is not limited to the above-described embodiment, and various additions, modifications, and deletions are possible without departing from the scope of the present invention. Therefore, such modifications are also included in the scope of the present invention. [Explanation of symbols]

[0039] 1:Canned battery 2: Negative electrode (the rim of the upper part of the can) 3: Positive electrode (top cover convex part) 5: Can bottom 7: Negative electrode connection terminal 8: Positive electrode connection terminal 10, 11: Welding electrodes 14: Projection 15: Slit 16: Separation slit 17: First welding point 18: Second welding point 19: Negative electrode connection terminal 21: Projection 22: Slit 23: Projection 24: Slit A, A1: Welding current

Claims

1. A resistance welding device for battery connection terminals, in which a positive electrode on a top lid protrusion of a can-shaped battery and a plate-shaped positive electrode connection terminal, and a negative electrode on the periphery of the top of the can and a plate-shaped negative electrode connection terminal are brought into contact with an outer surface of each connection terminal opposite the battery by a pair of welding electrodes from the same direction, and the welding electrodes are energized for resistance welding, thereby electrically connecting the positive electrode and negative electrode of the battery to each connection terminal, respectively, At least a pair of radially extending projections are formed on the negative electrode connecting terminal and are adjacent to welding points of the peripheral edge portion facing each other in the circumferential direction, and a welding current is induced and concentrated in the projections, thereby suppressing welding energy; A slit extending in a direction intersecting the radial direction is formed at a radial tip position of the projection, thereby suppressing the welding current and suppressing heat generation. Resistance welding equipment for battery electrode connection terminals.

2. In claim 1, a pair of projections are formed on the negative electrode connecting terminal, the pair of projections being arranged adjacent to each other in the circumferential direction at welding points that are circumferentially opposed to each other in the peripheral portion, and the negative electrode connecting terminal and the negative electrode are resistance-welded sequentially at each welding point by a pair of welding electrodes via the projections.

3. In claim 1, A resistance welding device for battery electrode connection terminals, wherein each connection terminal is made of plate-shaped copper or copper alloy.

4. A resistance welding device for battery electrode connection terminals, which makes it possible to directly cool each battery electrically connected by the resistance welding device according to any one of claims 1 to 3 with a coolant on the can bottom side.

5. A method for resistance welding electrode connection terminals of a battery, comprising the steps of: contacting an outer surface of each connection terminal opposite the battery with a pair of welding electrodes from the same direction between a positive electrode of a top lid protrusion of a can-shaped battery and a plate-shaped positive electrode connection terminal, and between a negative electrode of a peripheral portion of an upper portion of the can and a plate-shaped negative electrode connection terminal, and conducting current through the welding electrodes for resistance welding, thereby electrically connecting the positive electrode and negative electrode of the battery to each connection terminal, respectively, the method comprising the steps of: At least a pair of radially extending projections are formed on the negative electrode connecting terminal, adjacent to welding points of the peripheral edge portion that face each other in the circumferential direction, and a welding current is induced and concentrated in the projections to suppress welding energy; a slit extending in a direction intersecting the radial direction is formed at a radial tip position of the projection, thereby suppressing a welding current and suppressing heat generation; A method for resistance welding terminals for connecting battery electrodes.

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