JP2006139987A - Plate-shaped wiring material for battery pack, and the battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plate-shaped wiring material for a battery pack suppressing heat generation in the use of a battery to a substantially low level, enhancing weldability and corrosion resistance, and stably manufacturing a clad material, without generating a rippling phenomenon, for example, in the adhesion interface between the clad materials when the clad material is manufactured by rolling, and to provide a battery pack that uses this wiring material. <P>SOLUTION: The battery pack 3 is manufactured by electrically connecting in series four batteries 1 which are a secondary battery such as a nickel-cadmium battery, a lithium ion battery, and a nickel hydrogen battery with the plate-shaped wiring material 2. The plate-shaped wiring material 2 is a nickel/copper/nickel clad material, having a thickness of 0.5 mm or smaller, formed by integrally laminating nickel layers on both sides of a copper layer, the conductivity of the whole clad material is 75% or higher, the ratio of the thickness of the nickel layers on the both sides to the thickness of the whole clad material is 12.5-15%, and the total of the ratios of the thickness of the nickel layers on both sides is 25% or higher. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a battery pack plate-like wiring material and a battery pack for connecting a secondary battery such as nickel cadmium, lithium ion, or nickel hydride used in a personal computer, and in particular, suppressing heat generation during battery use. The present invention relates to a plate-like wiring material for battery packs that can be manufactured while being excellent in resistance weldability and corrosion resistance, and can be stably manufactured by rolling, and a battery pack using the same.

FIG. 9 shows a plan view of a conventional battery pack.
The battery pack 30 is obtained by electrically connecting four batteries 1 made of a secondary battery such as nickel / cadmium, lithium ion, or nickel hydride in series with a plate-like wiring member 22. The terminals 4 of each battery 1 and the plate-like wiring member 22 are electrically connected by spot welding which is a kind of resistance welding.

  As such a plate-like wiring member 22, it is necessary to select a material having low electrical resistance, excellent corrosion resistance to the electrolyte solution used in the battery 1, and good weldability with the electrode and the battery case.

From this point, pure nickel having a high corrosion resistance and a low electric resistance (8 to 10 μΩ · cm or less) is used for the plate-like wiring member 22. However, with the recent increase in capacity and power of secondary batteries, even nickel having a low electric resistance may generate heat, so a material with a lower electric resistance is desired. In addition, nickel has a problem that heat conductivity is high and it takes a long heating time at the time of welding, productivity is poor, and if it is heated too much, the battery case is heated and adversely affects the inside of the battery. For this, there is a method of increasing the cross-sectional area of nickel, but an increase in the cross-sectional area is not easily allowed due to space problems.
On the other hand, copper and copper alloys have a low electrical resistance of 1 to 2 μΩ · cm and good conductivity, but have a problem that corrosion resistance is insufficient and welding is very difficult.
Furthermore, recently, there is a demand for making the entire thickness of the plate-like wiring material as thin as possible.

In view of such points, a nickel / copper / nickel clad material is adopted, the ratio of the thickness of the Ni layer to the whole is 46.6% to 86.7%, and the electric resistance is 7 μΩ · cm or less. A thin plate-like wiring material having an overall thickness of 0.5 mm or less has been proposed (see Patent Document 1).
JP 11-297300 A

  However, even in the nickel / copper / nickel clad material, the suppression of heat generation due to the increase in capacity of the secondary battery is still insufficient, and the customer's request to suppress the heat generation below the level before increasing the capacity is required. I couldn't meet enough.

  Furthermore, according to the study by the present inventors, it is difficult to ensure weldability even if the ratio of the nickel layer is too small, and nickel / copper / nickel clad materials having different hardnesses are manufactured by rolling. At that time, it has been found that a phenomenon such as undulation occurs in the adhesion interface of the clad material.

  Accordingly, an object of the present invention is to solve the above-mentioned problems, optimize the structure of the nickel / copper / nickel clad material, and suppress heat generation during battery use to a sufficiently low level as a battery pack plate-like wiring material. In addition, it is excellent in resistance weldability and corrosion resistance. Furthermore, when producing a clad material by rolling, the clad material can be produced stably without causing a phenomenon such as undulation at the adhesion interface of the clad material. The object is to provide a plate-like wiring material and a battery pack using the same.

  In order to solve the above-mentioned problems, the battery pack plate-like wiring material of the present invention is a nickel / copper / nickel clad material having a thickness of 0.5 mm or less in which nickel layers are arranged on both sides of a copper layer and laminated and integrated. The battery pack plate-like wiring material, wherein the conductivity of the entire cladding material is 75% or more, and the ratio of the thickness of the nickel layers on both sides to the thickness of the entire cladding material is 12.5 to The total thickness ratio of the nickel layers on both sides is 25% or more.

  The thickness of the nickel layer disposed on both sides of the copper layer is preferably 0.025 to 0.05 mm.

  The thickness of the nickel layer disposed on both sides of the copper layer can be made equal.

  A projection having a radius of 0.5 to 5.0 mm and a depth of 0.05 to 1.0 mm can be formed on the clad material so as to be positioned at a welded portion with the battery.

  In order to solve the above problems, the battery pack of the present invention is a battery pack in which a plurality of secondary batteries are electrically connected in series with a battery pack plate-like wiring material made of nickel / copper / nickel clad material. The clad material is made of a nickel / copper / nickel clad material having a thickness of 0.5 mm or less in which nickel layers are arranged on both sides of the copper layer and integrated, and the conductivity of the clad material is 75% or more. In addition, the ratio of the thickness of the nickel layers on both sides to the thickness of the entire cladding material is in the range of 12.5 to 15%, respectively, and the total ratio of the thicknesses of the nickel layers on both sides is 25% or more. It is characterized by being.

  A projection having a radius of 0.5 to 5.0 mm and a depth of 0.05 to 1.0 mm can be formed on the clad material so as to be positioned at a welded portion with the secondary battery.

  The terminal of the secondary battery and the plate-like wiring material for battery pack can be electrically connected by spot welding.

  According to the present invention, the thickness ratio of the nickel / copper / nickel clad material is specified to optimize the structure, so that heat generation during battery use can be suppressed to a sufficiently low level and resistance can be reduced. Excellent weldability and corrosion resistance. Furthermore, when producing a clad material by rolling, the clad material can be produced stably without causing a phenomenon such as undulation at the adhesion interface of the clad material. For this reason, it becomes a suitable thing as a plate-shaped wiring material for battery packs.

  The inventors of the present invention have investigated the electrical conductivity of the clad material necessary for suppressing heat generation during battery use by producing a nickel / copper / nickel clad material having a thickness of 0.5 mm or less by rolling. It was found that the overall conductivity should be 80% ± 5% or more.

  At this time, the thickness of the nickel layer required to maintain resistance weldability and high corrosion resistance was examined from the viewpoint of securing peel strength (connectivity) after resistance welding. It was found that the ratio of the thickness of the nickel layers on both sides to the total required 25% or more.

On the other hand, when the processing conditions for producing a nickel / copper / nickel clad material made of such a thin composite material having different hardness by rolling were investigated, the thickness of the nickel layers on both sides with respect to the thickness of the entire clad material The ratio was found to be 12.5% or more for each. This is because if it is less than 12.5%, especially 10% or less, nickel cannot be attached to the elongation of copper during rolling, and a ripple phenomenon in which the adhesion interface between nickel and copper undulates easily occurs, and the production yield of the clad material is remarkably reduced. It is because it will do.
Further, if the thickness ratio of the nickel layers on both sides with respect to the thickness of the entire cladding material exceeds 15%, it becomes difficult to maintain the electrical conductivity of the entire cladding material at 80% ± 5% or more. I understood that.

For this reason, when the thickness of the entire cladding material is as thin as 0.5 mm or less, the ratio of the thickness of the nickel layer on both sides to the thickness of the entire cladding material is in the range of 12.5 to 15%, respectively. It ’s fine.
Incidentally, the greater the ratio of the thickness of the nickel layer to the thickness of the entire cladding material, the greater the beer strength (connectivity) after resistance welding, but the heat generation suppression effect based on the presence of intermediate copper and conductivity decreases. .

  The thicknesses of the nickel layers on both sides are each preferably 0.025 to 0.05 mm, and the thicknesses are preferably the same. If the thicknesses of the nickel layers on both sides are the same, it can be said that the clad material has no distinction between the front and back sides and is very easy to handle. Also, it can be said that the number of materials to be prepared is small in terms of manufacturing the clad material, which is advantageous in terms of cost.

  The thickness of the clad material can be 0.5 mm or less, for example, a thickness as thin as 0.1 mm in addition to 0.4 mm or 0.2 mm.

  In the present invention, the copper layer and the nickel layer are basically a pure copper layer and a pure nickel layer, but may contain a small amount of an additive component for improving characteristics.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 shows a plan view of a battery pack according to the present embodiment.
The battery pack 3 is obtained by electrically connecting four batteries 1 made of secondary batteries such as nickel / cadmium, lithium ion, nickel metal hydride, etc. in series with a plate-like wiring member 2. The terminal 4 and the plate-like wiring member 2 of each battery 1 are electrically connected by spot welding which is a kind of resistance welding.

FIG. 2 shows a cross-sectional view of the plate-like wiring member 2 used in the battery pack of FIG.
The plate-like wiring member 2 is composed of a nickel / copper / nickel clad material 5. The total thickness of the nickel / copper / nickel clad material 5 is 0.2 mm, the thickness of the copper plate 6 as the core material is 0.15 mm, and the thickness of the nickel plates 7 on both sides is 0.025 mm. The ratio of the thicknesses of the nickel plates 7 on both sides to the thickness of the entire nickel / copper / nickel clad material 5 is 12.5%. The nickel / copper / nickel clad material 5 has a plate width of 20 mm and an electrical conductivity of 80% (IACS).

  The clad material 5 is manufactured by disposing nickel plates 7 on both sides of the copper plate 6 and press-contacting them by rolling. In the production of a clad material by rolling, the rolling orientation is reduced by reducing the rolling reduction ratio once and rolling several times at a rolling reduction ratio of 65% to 80%, and by appropriately performing heat treatment at around 700 ° C. And the mechanical and electrical characteristics can be stabilized.

FIG. 3 shows the results of examining the relationship between the energization current and the temperature rise using the plate-like wiring material made of the clad material 5 shown in FIG.
Comparative Example 1 is a plate-like wiring material using a nickel material having a thickness of 0.2 mm (conductivity 20%), and Comparative Examples 2 to 4 are nickel / copper / nickel claddings having a thickness of 0.3 mm. About the Example of patent document 1 which consists of materials, thickness (ratio) of each layer is 0.07 mm (23.3%) / 0.16 mm (53.4%) / 0.07 mm (23.3%) In the case (Comparative Example 2), when the thickness (ratio) of each layer is 0.06 mm (20%) / 0.12 mm (40%) / 0.12 mm (40%) (Comparative Example 3), the thickness of each layer (Ratio) is 0.06 mm (20%) / 0.04 mm (13.3%) / 0.2 mm (66.7%) (Comparative Example 4).

From FIG. 3, it can be seen that in this example, the rate of temperature rise with respect to the energized current is smaller than in Comparative Examples 1 to 4, and the temperature rise suppression effect is excellent.
Note that Comparative Examples 2 to 4 have a slight temperature rise suppressing effect as compared with Comparative Example 1, but are not sufficient as compared with the present Example, and may not be able to respond to customer requests.

  FIG. 4 shows a case where a nickel / copper / nickel clad material having a total thickness of 0.2 mm is spot welded to a battery terminal to form a connection portion, and a current flows reliably to the battery terminal. The relationship between the ratio of the nickel layer to the total thickness and the peel rupture load (N) of the connecting portion was examined.

  From Fig. 4, in order to obtain the peel strength of 30N or more, which is the customer's request, considering the variation in the measured values, the nickel layer ratio is not sufficient at 16%, and it is 25% or more as a safe range for use. It turns out that it is necessary. The upper limit of the nickel layer ratio is naturally limited due to the relationship with the conductivity of the entire cladding material.

FIG. 5 shows another modification of the plate-like wiring member.
In the plate-like wiring material of FIG. 5A, in order to improve resistance weldability with the clad material 11 having the same structure as the clad material 5 shown in FIG. A projection 13 made of a projection is provided.

  As shown in FIG. 6, the size of each projection 13 is formed such that the radius R is in the range of 0.5 mm to 5.0 mm and the height h is in the range of 0.05 mm to 1.0 mm. .

  The reason why the size of the projection 13 is within the above range is that the effect of improving the weldability is reduced outside this range, which is not preferable.

  Thus, by forming the projection 13 on the clad material 11, the current density at the time of resistance welding is improved, and better bonding can be obtained.

  Further, as shown in FIG. 5B, two projections 15 may be formed in one place on the clad material 11.

When manufacturing the battery pack, the welded portion of the battery pack plate-like wiring member and the tab material of the tabbed battery are welded by resistance welding.
7 and 8 show examples of resistance welding apparatuses used for resistance welding.
7 is a plan view of the resistance welding apparatus, and FIG. 8 is a cross-sectional view of the resistance welding apparatus of FIG.

  This resistance welding apparatus includes a ceramic plate (welding table) 29 for placing a clad material (tab material) 21 of a battery with a tab, a welding electrode 27b in contact with the clad material 21 of the battery with a tab, A welding electrode 27a that is provided at a predetermined interval from the welding electrode 27b and is in contact with the cladding material (conductive plate-like member) 23 stacked on the cladding material 21, and between the welding electrode 27a and the welding electrode 27b. And a power source (not shown) for applying a voltage to the main circuit.

  To perform welding using this resistance welding apparatus, first, the clad material 21 of the battery with tabs is placed on the ceramic plate 29, and the welding electrode 27b is brought into contact with a predetermined position on the clad material 21, The clad material 23 is overlapped at another predetermined position on the clad material 21 of the battery with a tab so as to sandwich the projection 25, and the welding electrode 27a is further contacted from the back side of the clad material 23. A predetermined voltage is applied between the welding electrode 27a and the welding electrode 27b for a predetermined time.

The clad material 23 to be a conductive plate-like member is made of Ni / Cu / Ni, and the weld has conductivity suitable for resistance welding (conductivity is 80% ± 5% or more IACS). In 25, since the current density is improved, the clad material 21 and the welded portion of the clad material 23 are welded with good strength.
For this reason, it becomes possible to provide a battery pack capable of increasing the capacity by connecting a desired number of secondary batteries.

1 is a plan view showing a battery pack according to Example 1. FIG. 3 is a cross-sectional view showing a structure of a plate-like wiring member used in Example 1. FIG. In Example 2, it is the graph which showed the relationship between an energization current and a temperature rise. In Example 3, it is the graph which showed the relationship between the ratio of the nickel layer with respect to the thickness of the whole clad material, and the peel breaking load (N) of a connection part. It is a top view which shows the structure of the plate-shaped wiring material of Example 4, (a) is what provided one projection per location, (b) is what provided two projections per location. It is sectional drawing which shows the structure of the plate-shaped wiring material of Example 4. 6 is a plan view of a resistance welding apparatus used in Example 5. FIG. It is a cross-sectional view of the resistance welding apparatus of FIG. It is a top view which shows the conventional battery pack.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery 2 Plate-shaped wiring material 3 Battery pack 4 Terminal 5 Cladding material 6 Copper plate 7 Nickel plate 11 Cladding material 13 Projection 15 Projection 16 Copper plate 17 Nickel plate 21 Clad material 22 Plate-shaped wiring material 23 Cladding material 25 Projection 27a Welding electrode 27b Welding Electrode 30 Battery pack

Claims (7)

  A plate-like wiring material for a battery pack made of nickel / copper / nickel clad material having a thickness of 0.5 mm or less, in which nickel layers are arranged on both sides of a copper layer and integrated, and the conductivity of the clad material as a whole Is 75% or more, the ratio of the thickness of the nickel layers on both sides to the thickness of the entire cladding material is in the range of 12.5 to 15%, respectively, and the sum of the ratios of the thicknesses of the nickel layers on both sides Is a plate-like wiring material for battery packs, characterized by being 25% or more.   The plate-like wiring material for a battery pack according to claim 1, wherein the nickel layers disposed on both sides of the copper layer each have a thickness of 0.025 to 0.05 mm.   The plate-like wiring material for a battery pack according to claim 1 or 2, wherein the nickel layers disposed on both sides of the copper layer have the same thickness.   2. The battery pack according to claim 1, wherein a projection having a radius of 0.5 to 5.0 mm and a depth of 0.05 to 1.0 mm is formed on the clad material so as to be positioned at a welding portion with the battery. Plate wiring material. A battery pack in which a plurality of secondary batteries are electrically connected in series with a plate-like wiring material for a battery pack made of nickel / copper / nickel clad material,
The clad material is made of a nickel / copper / nickel clad material having a thickness of 0.5 mm or less in which nickel layers are arranged on both sides of the copper layer and integrated, and the conductivity of the clad material is 75% or more. In addition, the ratio of the thickness of the nickel layers on both sides to the thickness of the entire cladding material is in the range of 12.5 to 15%, respectively, and the total ratio of the thicknesses of the nickel layers on both sides is 25% or more. A battery pack characterized by being.   6. A projection having a radius of 0.5 to 5.0 mm and a depth of 0.05 to 1.0 mm is formed on the clad material so as to be positioned at a welded portion with the secondary battery. Battery pack. 6. The battery pack according to claim 5, wherein the terminal of the secondary battery and the plate-like wiring material for the battery pack are electrically connected by spot welding.

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