JP2006019155A - Battery pack, battery and connection joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery pack, a battery and a connection joint which can prevent corrosion of terminals even in the case of connecting terminals made of different metals. <P>SOLUTION: The battery pack is composed of more than two serially connected secondary batteries 1 including an electrode 11, a laminate film 14 enclosing the electrode 11, and a positive terminal 12 and a negative terminal 13 both of which are connected to the electrode 11 and projected from the laminate film 14. A joint of terminals of adjacent secondary batteries 1 is covered with an insulation film 15 at least in a part of whole of projected part of the terminal having higher self-potential (the negative terminal 13) from the laminate film 14 except for a part (an exposed part 18) used for the connection with the terminal of an adjacent battery (the positive terminal 12). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an assembled battery in which a plurality of batteries are connected, the battery, and a connection joint such as a joint portion between terminals of the battery. More specifically, for example, the present invention relates to a battery in which both terminals such as a secondary battery are made of different metals, an assembled battery in which the terminals of the battery are joined together, and a connection joint that is a joined part thereof.

  Conventionally, a laminate-type lithium ion battery has been widely used as an example of a small and lightweight secondary battery. This laminated lithium ion battery generally has a copper terminal and an aluminum terminal as bipolar terminals. Here, when this laminated lithium-ion battery is used in a device that requires a large amount of power, such as an automobile, since the voltage obtained by the battery alone is low, a plurality of batteries are often connected in series. . In this case, it is necessary to join both terminals made of different metals.

  However, it has been found that when dissimilar metals are joined as they are, corrosion proceeds even with slight moisture in the air due to the local battery phenomenon. For example, in the case of a joint between copper and aluminum, the aluminum is corroded. Various methods have been tried to cope with this problem. For example, there is one in which a member such as a SUS material is sandwiched therebetween and connected by bolt fastening so that a copper terminal and an aluminum terminal are not in direct contact. This method has a problem that the number of parts is large and the connection resistance increases.

On the other hand, the technique which covered the terminal and the junction part of a terminal with a film, a resin material, etc., and prevented that a water | moisture content adheres is devised (for example, refer patent document 1, patent document 2). In the technique described in Patent Document 1, a lead in which joint portions of a plurality of conductive materials are covered with an insulating film is proposed. In the technique described in Patent Document 2, a connection structure is proposed in which a foil-like terminal of a flat battery is covered with an insulating material layer, and a lead material is welded to the foil-like terminal.
JP 2002-8622 A JP 2002-50340 A

  However, the conventional techniques described above have the following problems. In the technique described in Patent Document 1, both terminals are coated after being joined. In the case of a battery, the terminal is attached to the battery body and the batteries are connected in series. The work of covering with an insulating film in this state is generally poor in workability. Furthermore, if any trouble occurs during the covering operation, there is a problem that the whole connected batteries may be wasted.

  In addition, when a resin insulating material is coated on a terminal or the like as in the technique described in Patent Document 2, there is a possibility that a pinhole or the like due to a coating defect may occur. When a pinhole or the like occurs, there is a problem that corrosion may progress from the portion toward the inside.

  The present invention has been made to solve the problems of the conventional techniques described above. That is, an object of the present invention is to provide an assembled battery, a battery, and a connection joint that can prevent corrosion of terminals even when both terminals of dissimilar metals are joined.

  The assembled battery of the present invention made for the purpose of solving this problem includes two or more batteries having a power generation element, a packaging member that wraps the power generation element, and bipolar terminals that are connected to the power generation element and project from the packaging member. A battery assembly connected in series, where the terminal joint between adjacent batteries has at least the terminal of the adjacent battery out of the entire portion of the terminal protruding from the packaging member of the terminal having a higher natural potential. The part excluding the part used for the connection is covered with an insulating material.

  According to the assembled battery of the present invention, the terminal with the higher natural potential of the battery to be connected excludes at least the part used for connection with the terminal of the adjacent battery among the whole part protruding from the packaging member. The part is covered with insulating material. That is, since the connection portion is not covered, the connection resistance is small. On the other hand, since most of the other parts are covered with an insulating material, there is almost no exposed metal area with a high natural potential. Even if it is slightly exposed, the slight corrosion current is distributed over a large exposed area of the other terminal, so that the metal corrosion hardly proceeds. Therefore, even when both terminals of dissimilar metals are joined, the assembled battery can prevent corrosion of the terminals.

Furthermore, in the present invention, the insulating material is preferably in the form of a film.
In this way, work is easier than coating, and insulation defects such as pinholes are less likely to occur.

  The present invention also provides a battery having a power generation element, a packaging member that wraps the power generation element, and a bipolar terminal that is connected to the power generation element and protrudes from the packaging member. Of the entire portion protruding from the member, at least the portion excluding the portion used for connection with the terminal of another battery extends to the battery covered with the insulating material.

Furthermore, the connection joint of the present invention is a connection joint formed by connecting terminals whose one end is wrapped in a packaging member and the other end protrudes from the packaging member, from the packaging member of the terminal having a higher natural potential. Of the entire protruding portion, at least a portion excluding a portion used for connection with a connection partner terminal is covered with an insulating material.
If two or more batteries of the present invention are connected in series with this connection joint, the assembled battery of the present invention can be obtained.

  According to the assembled battery, battery, and connection joint of the present invention, even when both terminals of different metals are joined, corrosion of the terminals can be prevented.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best mode for embodying the present invention will be described in detail with reference to the accompanying drawings. In the present embodiment, the present invention is applied to a laminated secondary battery and a battery pack formed by connecting a plurality of the secondary batteries in series.

  The secondary battery 1 of this embodiment is a laminate type lithium ion battery. As shown in FIG. 1, the secondary battery 1 includes a substantially rectangular and flat electrode body 11, and flat plate-like positive electrode terminals 12 and negative electrode terminals 13 respectively connected to the electrode bodies 11. . The electrode body 11 is formed by winding a positive electrode plate and a negative electrode plate with a separator sheet interposed therebetween, and a positive electrode terminal 12 is connected to the positive electrode plate, and a negative electrode terminal 13 is connected to the negative electrode plate. Furthermore, the electrode body 11 is entirely covered with a laminate film 14, and the tip portions of the positive electrode terminal 12 and the negative electrode terminal 13 protrude from the same position in the vertical direction of the laminate film 14 to the left and right, respectively.

  As shown in FIG. 1, insulating films 15 having different sizes are attached to the positive terminal 12 and the negative terminal 13. Furthermore, a through hole 16 having the same diameter is provided at the tip of the positive electrode terminal 12 and the negative electrode terminal 13. Specifically, the base of the positive electrode terminal 12 is made of aluminum, and the insulating film 15 is attached only to the contact point with the laminate film 14. Therefore, the base aluminum is exposed around the through hole 16 of the positive terminal 12.

  On the other hand, in the negative electrode terminal 13, the base material 17 is made of copper, and a continuous insulating film 15 is attached from the contact point with the laminate film 14 to the tip. Around the through hole 16 of the negative electrode terminal 13, a hole slightly larger than the through hole 16 is provided in the insulating film 15 on both sides, and an annular exposed portion 18 in which the base material 17 is exposed is formed. Accordingly, the negative electrode terminal 13 is entirely covered with the insulating film 15 except for the exposed portion 18 outside the laminate film 14.

  Even if the insulating film 15 is condensed on the outer surface of the laminate film 14 by increasing the insulation function between the laminate film 14 and the terminals 12 and 13 and the extended surface distance, no water droplets are formed on the terminals 12 and 13. It has the function to make it. The insulating film 15 is the same as the film conventionally provided for insulation between the terminal member and the laminate film 14. The through hole 16 is for connecting the terminals 12 and 13 to each other.

  The negative electrode terminal 13 is manufactured as a single unit as shown in FIG. First, the base material 17 having the through holes 16 as shown in FIG. The whole of the base material 17 is a flat plate made of copper. As shown in FIG. 2 (b), the insulating film 15 is pasted with the end portion on the base end side without the through hole 16 remaining. A hole having a predetermined size is provided in the insulating film 15 in advance, and the hole is arranged around the through hole 16. As a result, the exposed portion 18 is formed. Alternatively, the exposed portion 18 may be formed by pasting the insulating film 15 in which no hole is formed and then cutting off the periphery of the through hole 16.

Since it is manufactured in this way, even if some trouble occurs at the stage of attaching the insulating film 15 to the negative electrode terminal 13, only the negative electrode terminal 13 needs to be disposed of. Since it is not yet connected to the electrode body 11, reuse and the like are easy.
On the other hand, the positive electrode terminal 12 is manufactured by attaching the insulating film 15 only to the periphery of the contact point with the laminate film 14 on the aluminum base material having the same shape as the base material 17 of the negative electrode terminal 13. And the secondary battery 1 is manufactured by connecting the positive electrode terminal 12 and the negative electrode terminal 13 which were manufactured in this way to the electrode body 11 by a general method.

  Next, an assembled battery 2 in which a plurality of secondary batteries 1 are connected in series is shown in FIG. In the assembled battery 2, a plurality of secondary batteries 1 are arranged side by side, and the positive terminals 12 and the negative terminals 13 of the adjacent secondary batteries 1 are joined to each other by a joint 10. Here, in the joint portion 10, the through holes 16 of both terminals 12, 13 are arranged to be overlapped and fastened by bolts 19. That is, in the joint portion 10, the base materials of both electrodes are in direct contact with each other in the range of the exposed portion 18 around the through hole 16. This part is an electrical contact. On the other hand, the outer exposed portion 18 is covered with a general SUS washer.

  According to the assembled battery 2, the copper member is hardly exposed at the joint 10. Even if there is a pinhole in the insulating film 15 of the negative electrode terminal 13 or the washer does not completely cover the exposed portion 18, the exposed copper area is very small. On the other hand, most of the positive electrode terminal 12 is exposed. As a result, the exposed area of the aluminum member is much larger than that of the copper member.

  Therefore, even if a defect such as a pinhole occurs in the insulating film 15 and copper is slightly exposed, the corrosion current due to this is dispersed on the vast surface of aluminum in the positive electrode terminal 12. The Rukoto. Therefore, the rate at which aluminum is corroded is very small. Thereby, in this assembled battery 2, corrosion of the aluminum member is well prevented at the joint 10.

  This inventor formed the Example similar to the junction part 10 of the positive electrode terminal 12 and the negative electrode terminal 13 of this form, and performed the acceleration test compared with the comparative example. In both cases, a general salt spray test was performed by fixing a copper plate having the same thickness on an aluminum plate having a thickness of 300 μm. Specifically, 5% salt water was continuously sprayed in an environment of a temperature of 35 ° C. and a humidity of 98%. And the average board thickness of the part which is not corroded among aluminum boards was measured after progress for a predetermined time. The result is shown in the graph of FIG.

  In FIG. 4, a graph L <b> 1 indicated by a circle is the present example, and the surface of the copper plate was covered with aluminum in the same manner as the structure of the joint 10. A graph L2 indicated by Δ is Comparative Example 1, in which a SUS material is sandwiched between an aluminum plate and a copper plate. A graph L3 indicated by □ is Comparative Example 2, and neither a coating nor a SUS material is used. As can be seen from this figure, in the present example, the original aluminum plate having a thickness of 300 μm remained with an aluminum plate having a thickness of 270 μm or more even after 200 hours or more had elapsed. Here, some corrosion occurs due to the self-corrosion of aluminum. On the other hand, the corrosion progressed until the remaining thickness was 240 μm in Comparative Example 1 and the remaining thickness was 50 μm in Comparative Example 2.

  As described above in detail, according to the secondary battery 1 of the present embodiment, the negative electrode terminal 13 is manufactured by simply attaching the insulating film 15 to the terminal member 17 before connection. The insulating film 15 is conventionally pasted to insulate the welded portion with the laminate film 14, and since it has only been enlarged, no new process is added. Therefore, manufacture is easy. Furthermore, since the base material of both the terminals 12 and 13 is directly joined by the exposed portion 18, the connection resistance is small. And since all the copper base materials 17 are covered outside the laminate film 14, corrosion between different metals does not occur. Even if the insulating film 15 is slightly scratched, the exposed copper is so small that the rate at which aluminum is corroded is very small. Accordingly, even in the assembled battery 2 in which both the terminals 12 and 13 are joined, the corrosion of the terminals 12 and 13 can be prevented, and the assembled battery 2 can obtain a long life.

In addition, this form is only a mere illustration and does not limit this invention at all. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof.
For example, in the above embodiment, the exposed portions 18 are provided on both surfaces of the negative electrode terminal 13, but the exposed portions 18 may be provided on only one surface and the surfaces may be in contact with the positive electrode terminal 12. In that case, the washer may be omitted.
For example, in the above embodiment, the negative electrode terminal 13 is covered with the insulating film 15, but other than the insulating film 15, coating with an insulating material may be used. In this case, the coating range is from the tip of the substrate 17 to the range of the insulating film 15 (excluding the exposed portion 18). In this case, the insulating film 15 may be as small as the positive electrode terminal 12.
Further, for example, the fixing method of the terminals 12 and 13 may be ultrasonic welding instead of fastening with the bolts 19. In that case, the through-hole 16 and the exposed part 18 are unnecessary.
Further, for example, in the above embodiment, the present invention is applied to the negative electrode terminal 13 of the secondary battery 1, but the present invention is not limited to this as long as it is a joint between different metals.

It is explanatory drawing which shows schematic shape of the secondary battery to which the terminal structure of this form was applied. It is explanatory drawing which shows the manufacturing method of a negative electrode terminal. It is explanatory drawing which shows schematic shape of the assembled battery which connected multiple secondary batteries. It is a graph which shows the result of the comparison experiment of the terminal structure of this form, and the conventional terminal structure.

Explanation of symbols

1 Secondary battery (battery)
2 battery pack 10 joint (connection joint)
11 Electrode body (power generation element)
12 Positive terminal (terminal)
13 Negative terminal (terminal)
14 Laminate film (packaging material)
15 Insulating film (insulating material)

Claims (4)

In an assembled battery formed by connecting in series two or more batteries having a power generation element, a packaging member that wraps the power generation element, and a bipolar terminal that is connected to the power generation element and protrudes from the packaging member,
The terminal junction between adjacent batteries is
That the portion of the terminal with the higher natural potential that protrudes from the packaging member, except for the portion used for connection with the terminal of the adjacent battery, is covered with an insulating material. A battery pack featuring the features. The assembled battery according to claim 1,
The battery pack is characterized in that the insulating material is in the form of a film. In a battery having a power generation element, a packaging member that wraps the power generation element, and a bipolar terminal that is connected to the power generation element and protrudes from the packaging member,
The terminal with the higher natural potential should have at least the part of the part protruding from the packaging member except the part used for connection with the terminal of the other battery covered with an insulating material. Battery characterized. In a connection joint in which one end is wrapped in a packaging member and the other end is connected to terminals protruding from the packaging member,
It is characterized in that at least the portion of the terminal with the higher natural potential protruding from the packaging member excluding the portion used for connection with the terminal of the connection partner is covered with an insulating material. Connection fittings.

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