WO2015145715A1

WO2015145715A1 - Cell terminal and cell

Info

Publication number: WO2015145715A1
Application number: PCT/JP2014/059086
Authority: WO
Inventors: 浩志櫻井; 水田　政智
Original assignee: オートモーティブエナジーサプライ株式会社
Priority date: 2014-03-28
Filing date: 2014-03-28
Publication date: 2015-10-01
Also published as: JPWO2015145715A1; JP6227756B2

Abstract

　A positive electrode terminal (2) of a film-packaged cell (1) comprises a cladding in which a first metal portion (61) comprising aluminum and a second metal portion (62) comprising copper are joined at an interface (63). One end part (2a) is connected to a positive electrode collector (12) and the other end part (2b) is led out from a packaging body (5). A resin layer (41) joined to the packaging body (5) is provided around the interface (63). The interface (63) has a three-dimensional shape having a substantially V-shaped cross-section. Side edges (2c, 2d) of the positive electrode terminal (2) are squeezed to a tapered shape, and the interface (63) appearing at the surface converges in a straight line. The essential surface area of the interface (63) is thereby reduced.

Description

Battery terminals and batteries

The present invention relates to a battery terminal using a clad material and a battery using the terminal.

In Patent Document 1, in a film-clad battery such as a lithium ion battery, a positive electrode side or a negative electrode side terminal is made of a clad material obtained by bonding two kinds of metals (aluminum and nickel for a positive electrode terminal and copper and nickel for a negative electrode terminal). A structure in which a resin layer is provided on a part of the terminal in the length direction so as to cover the interface between the two is disclosed.

That is, since the positive electrode current collector in the power generation element is generally made of aluminum and the negative electrode current collector is generally made of copper, the inner end connected to each current collector is made of the same metal material as the current collector (Ie, aluminum for the positive terminal, copper for the negative terminal), while the outer end drawn to the outside is made of a dissimilar metal selected in consideration of the connection with the external terminal, bus bar, etc., for example, nickel It is composed.

The resin layer provided so as to cover the interface functions as an adhesive layer for the film-shaped outer package, and the sealing surface of the film-shaped outer package that is bonded to each other so as to sandwich the negative electrode terminal from both sides is on the resin layer. Glued.

In a terminal using such a clad material, in order to ensure a high bonding strength between the two metal parts, the interface between the two is a simple plane (typically a plane perpendicular to the length direction of the terminal). Instead, it is desirable to have a three-dimensional shape that also changes in the length direction of the terminal. However, the three-dimensional interface changed in the terminal length direction as described above appears in a simple straight line extending in the width direction of the terminal on both main surfaces, but spreads in the terminal length direction on the side surface of the terminal. It will appear in shape.

JP 2001-126709 A

The present invention is a battery terminal comprising a plate-like clad material in which a first metal constituting one end in the length direction and a second metal constituting the other end are joined via an interface extending in the width direction. is there.

The interface is shaped as a cross-section along the length direction of the terminal, and is longer than the start point appearing on one main surface of the terminal, the end point appearing on the other main surface, and the positions of these start and end points. And at least one top portion in the middle portion in the thickness direction, which is offset to one side in the direction. For example, the shape on the cross section along the length direction of the terminal is V-shaped or W-shaped.

And in one aspect of this invention, the side edge part of the terminal in which the both ends of the interface extended in the width direction are located in the shape crushed in the thickness direction.

Therefore, in the side edge portion, the interface expanded in the thickness direction is crushed so as to approach one linear shape, and the metal position exposed in a wide area moves in the length direction of the terminal. Therefore, the distance from the atmospheric humidity and the electrolytic solution can be increased, and the corrosion rate can be suppressed. Even if crushing is not complete, the surface area of the interface that is substantially exposed at the terminal side edge is reduced.

In the second aspect of the present invention, the first edge portion extending from the start point to the top portion and the second piece extending from the end point toward the top portion are the side edges of the terminal at which both ends of the interface extending in the width direction are located. The one part is converged in the thickness direction.

Therefore, at the side edge portion, the metal position exposed in a wide area moves in the length direction of the terminal by the amount of convergence, so the humidity from the atmosphere and the distance from the electrolyte can be separated, and the corrosion rate is reduced. Can be suppressed. Even if the convergence is not complete, the surface area of the interface that is substantially exposed at the terminal side edge is reduced, and the corrosion area can be reduced.

The perspective view which shows an example of the film-clad battery in which the terminal of this invention is used. Sectional drawing of a film exterior battery similarly. The longitudinal cross-sectional view of one Example of the terminal which concerns on this invention. FIG. 4 is a cross-sectional view taken along line AA in FIG. 3. The perspective view of the terminal before resin layer mounting | wearing. FIG. 6 is a cross-sectional view taken along line BB in FIG. The perspective view of the terminal which shows the base material state which has not crushed the side edge. Explanatory drawing of the angle of a taper surface. Explanatory drawing which shows the example of the combination of the direction of an interface at the time of applying to a positive electrode terminal, and the formation range of a resin layer. Explanatory drawing which shows the example of the combination of the direction of the interface at the time of applying to a negative electrode terminal, and the formation range of a resin layer.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

First, an example of the film-clad battery 1 in which the terminal according to the present invention is used will be described with reference to FIG. 1 and FIG. The film-clad battery 1 is, for example, a lithium ion secondary battery, and has a flat rectangular external shape as shown in FIG. 1 and includes a positive electrode terminal 2 and a negative electrode terminal 3 at one edge in the longitudinal direction. ing.

As shown in FIG. 2, the film-clad battery 1 is one in which the power generating element 4 is housed in an exterior body 5 made of a laminate film together with an electrolytic solution. The power generation element 4 has a laminated structure in which a plurality of positive electrodes 11 and negative electrodes 21 each having a sheet shape are alternately laminated via separators 31. The positive electrode 11 is configured by applying a positive electrode active material layer 13 on both surfaces of a positive electrode current collector 12 made of, for example, an aluminum foil, and the negative electrode 21 is formed on both surfaces of a negative electrode current collector 22 made of, for example, a copper foil. 23 is applied. In addition, the dimension of each part in a figure, and the number of the positive electrodes 11 and the negative electrodes 22 are not necessarily exact, and are exaggerated for explanation.

A part of the edge in the longitudinal direction of the negative electrode current collector 22 extends as a terminal connection portion 22a that does not include the negative electrode active material layer 23, and one end portion 3a of the negative electrode terminal 3 is connected to the tip thereof. Specifically, the terminal connection portions 22a of the plurality of negative electrodes 22 are superposed on the negative electrode terminal 3, and then joined together by ultrasonic welding. The other end 3 b of the negative electrode terminal 3 is led out of the exterior body 5.

Although not shown in FIG. 2, the positive electrode terminal 2 also has a similar connection structure, that is, a positive electrode active material layer 13 is provided on a part of the longitudinal edge of the positive electrode current collector 12. A terminal connection portion that is not to be extended is formed, and one end portion of the positive electrode terminal 2 is ultrasonically welded to the tip thereof. The other end of the positive electrode terminal 2 is led out of the exterior body 5.

The exterior body 5 that houses the power generation element 4 together with the electrolytic solution has a three-layer structure of a heat-fusible layer 51, a metal layer 52, and a protective layer 53 as shown in an enlarged view in FIG. 2. It has a laminate film. The intermediate metal layer 52 is made of, for example, an aluminum foil, and the heat-sealing layer 51 that covers the inner surface thereof is made of a synthetic resin that can be heat-fused, for example, polypropylene (PP), and is a protection that covers the outer surface of the metal layer 52. The layer 53 is made of a synthetic resin having excellent durability, such as polyethylene terephthalate (PET). A laminate film having a larger number of layers can also be used. In the above example, the synthetic resin layers are laminated on both surfaces of the metal layer 52. However, the synthetic resin layer on the outer side of the metal layer 52 is not necessarily essential, and the configuration includes the synthetic resin layer only on the inner surface. It may be.

In one example, the outer package 5 has a two-sheet structure of one laminate film disposed on the lower surface side of the power generation element 4 in FIG. 2 and another laminate film disposed on the upper surface side, The four sides around these two laminate films are superposed and heat-sealed to each other. The illustrated example shows such a two-layer exterior body 5. As another example, the exterior body 5 is made of one relatively large laminate film, and the power generation element 4 is arranged inside in a folded state, and the surrounding three sides are overlapped, and It can be set as the structure heat-sealed mutually.

The positive electrode terminal 2 and the negative electrode terminal 3 are arranged side by side on the short side of the rectangular film-clad battery 1, and these

terminals

2 and 3 are heated by overlapping the edge 5 a of the laminate film that becomes the outer package 5. At the time of fusion, it is led out through the joint surface 5b of both.

Specifically, a resin layer 41 is provided in advance on the outer peripheral surface of the intermediate portion in the length direction of the

terminals

2 and 3, and the edge 5 a of the outer package 5 is formed in such a manner as to sandwich the resin layer 41 from both sides. Bonded on the layer 41. As the resin layer 41, a resin material excellent in resistance to an electrolytic solution and adhesiveness is used. For example, an acid-modified polyolefin resin is used.

3 and 4 show an embodiment in which the present invention is applied to the positive electrode terminal 2, FIG. 3 is a cross section (longitudinal cross section) along the length direction of the positive electrode terminal 2, and FIG. It is a cross section along a line. The positive electrode terminal 2 is composed of a plate-like clad material in which aluminum as the first metal and copper as the second metal are integrally joined, and is connected to the positive electrode current collector 12 inside the exterior body 5. One end portion 2a in the length direction is constituted by the first metal portion 61 made of aluminum, and the other end portion 2b in the length direction led out from the exterior body 5 to the outside is made by the second metal portion 62 made of copper. It is configured. In this specification, the x direction in FIG. 3 which is the direction in which the

terminals

2 and 3 are derived is referred to as the “length direction” of the

terminals

2 and 3, and the y direction in FIG. Will be referred to as the “width direction”. This does not necessarily mean that the dimension in the x direction is larger than the dimension in the y direction. The z direction in FIG. 3 is referred to as the “thickness direction” of the

terminals

2 and 3.

The interface 63 between the first metal portion 61 and the second metal portion 62 exists at a substantially intermediate portion in the length direction of the positive electrode terminal 2, so that the one end portion 2 a of the positive electrode terminal 2 is entirely in the thickness direction. The other end portion 2 b is configured as a second metal portion 62 as a whole in the thickness direction. Thus, by using the positive electrode terminal 2 as a clad material, the first metal portion 61 is made a material suitable for bonding to the positive electrode current collector 12, and the second metal portion 62 is bonded to an external terminal, a bus bar, or the like. It can be made a material suitable for. For example, the positive electrode terminal 2 of the above embodiment can be used in combination with the negative electrode terminal 3 made entirely of copper, whereby the portions led out of the

terminals

2 and 3 are made of the same copper material. Is possible.

The interface 63 extends linearly over the entire width direction of the positive electrode terminal 2, but in order to ensure high bonding strength between the two types of

metal portions

61 and 62, the interface 63 is not a simple flat surface. As shown in FIG. 4, the interface 63 has a three-dimensional shape having a substantially V-shaped cross section. That is, the interface 63 of this embodiment has a thickness from the start point 63a appearing on the first main surface 64a of the positive electrode terminal 2 in the cross-sectional shape (Z direction) along the length direction of the

terminals

2 and 3 in FIG. The first piece 631 extending obliquely toward the middle portion in the direction and the second piece 632 extending obliquely from the end point 63b appearing on the second main surface 64b of the positive electrode terminal 2 toward the middle portion in the thickness direction are approximately The first piece 631 and the second piece 632 are formed symmetrically and are continuous with each other at the apex 63c at the intermediate portion in the thickness direction, thereby forming a substantially V-shaped cross section as a whole. Accordingly, with respect to the length direction of the

terminals

2 and 3, the position of the start point 63a of the interface 63 appearing on the first main surface 64a and the position of the end point 63b of the interface 63 appearing on the second main surface 64b are basically equal. Compared to these positions, the V-shaped top portion 63 c is located closer to the one end portion 2 a of the positive electrode terminal 2.

Note that the interface 63 may have a cross-sectional shape close to a U-shape, or a W-shaped cross-sectional shape having a plurality of top portions 63c.

The V-shaped cross-sectional shape of the interface 63 as described above basically has the same cross-sectional shape over the entire width direction excluding the side edges 2c and 2d of the positive electrode terminal 2 shown in FIG. On the other hand, as shown in FIGS. 5 and 6, the side edges 2c and 2d of the positive electrode terminal 2 are formed in a tapered shape that is crushed from above and below in the thickness direction. The one piece 631 and the second piece 632 are gradually converged in the thickness direction. That is, as shown in FIG. 7, the base material of the clad material in which two kinds of metals are joined has a V-shaped cross-section interface 63 continuous to the side surface 101 in the same cross-sectional shape. The

edges

102 and 103 on both sides of the terminal 101 are crushed in a taper shape from both sides in the thickness direction of the

terminals

2 and 3, so that a pair of tapered surfaces 104 and 105 ( 5) is formed. Then, with such plastic deformation of the base material, the first piece 631 and the second piece 632 of the interface 63 gradually converge as shown in FIG. 6, and finally close to one line. It is in shape. Further, the material of the first metal portion 61 (material of the portion indicated by reference numeral 61a in FIG. 7) existing in a triangle along the

edges

102 and 103 in the base material shown in FIG. 7 is collected in the center in the thickness direction, and By covering the second metal portion 62, the interface 63 that finally appears on the side edges 2c and 2d becomes thinner. Ideally, the interface 63 appearing on the side edges 2c and 2d has a long thin linear portion.

For example, the positive electrode terminal 2 has a length of 50 mm, a width of 70 mm, and a thickness of 0.2 mm. In one embodiment, as shown in FIG. 2c and 2d are crushed over a width W1 of about 1 mm, and the angle θ of each of the tapered

surfaces

104 and 105 is about 7 °.

The crushing of the

edges

102 and 103 at the side edges 2c and 2d can be performed simultaneously with the cutting of the side edges 2c and 2d.

As described above, it is not preferable from the viewpoint of corrosion that the interface which is the contact surface of the dissimilar metal in the clad material approaches the electrolytic solution or the outside air. In the present embodiment, the first metal portion covers the second metal portion, so that the distance from the exposed second metal portion can be increased, and the corrosion rate can be suppressed.

Further, even if the second metal portion is not completely covered by the first metal portion, the surface area of the interface that is substantially exposed at the terminal side edge is reduced, and the corrosion area can be reduced.

The resin layer 41 is provided on the surface of the positive electrode terminal 2 by an appropriate method such as application of a resin material or adhesion of a resin film after the processing of the side edges 2c and 2d. In the example of FIG. 5, the resin layer 41 is provided in the range of the length L between the

boundary lines

106 and 107.

Here, whether or not to provide the resin layer 41 so as to cover the entire length direction of the positive electrode terminal 2 of the interface 63 appearing in a straight line shape (or a very narrow V shape close to a straight line) on the side edges 2c and 2d is arbitrary. It is. That is, in the present invention, the

boundary lines

106 and 107 may be set so as to cover the entire length direction of the positive electrode terminal 2 of the interface 63 at the side edges 2c and 2d, or at the side edges 2c and 2d. The boundary lines 106 and 107 may be set so that one end of the positive electrode terminal 2 in the length direction of the interface 63 is exposed from the resin layer 41.

In the above embodiment, the top 63c of the interface 63 having a V-shaped cross section extends toward the first metal portion 61, but conversely, the interface 63 extends in the direction in which the top 63c extends toward the second metal portion 62. May be configured. FIG. 9 shows three other typical examples in which the orientation of the interface 63 and the formation range of the resin layer 41 are appropriately combined. In addition, in FIG. 9, in order to make an understanding easy, each example is shown by the base material state which has not crushed the

edges

102 and 103 of the side edges 2c and 2d.

The example of FIG. 9A has the same configuration as the embodiment described with reference to FIGS. 3 to 7, and the top 63c of the interface 63 extends toward the first metal portion 61 side. The boundary lines 106 and 107 of the resin layer 41 are set so that the entire length of the interface 63 is also covered with the resin layer 41 at the side edges 2c and 2d. In this embodiment, the side edges 2c, 2d can be crushed to separate the exposed position of copper, which is the second metal portion 62 at the side edges 2c, 2d, from the electrolyte on the first metal portion 61 side. Even if crushing is not complete, the surface area can be reduced.

9B is an example in which the direction of the interface 63 is reversed compared to FIG. The boundary lines 106 and 107 are set so as to allow exposure of the V-shaped interface 63 on the top 63c side. That is, in this example, the

boundary lines

106 and 107 and the interface 63 are set so that the margin between the boundary line 106 and the interface 63 is larger on the resin layer 41 on the first metal portion 61 side where the electrolytic solution exists. The relative positional relationship of is set. In the side edges 2c and 2d, the end of the interface 63 is exposed to the outside air, but the side edges 2c and 2d are crushed in the thickness direction to increase the distance between the outside air and the first metal portion 61. The corrosion of the exposed first metal portion 61 (not crushed) due to the outside air can be suppressed. Even if crushing is not complete, the substantial surface area can be reduced.

In the example of FIG. 9C, the boundary line 106, which has the same orientation of the interface 63 as in FIG. 9A, allows the start point 63a and end point 63b side of the interface 63 to be exposed from the resin layer 41. 107 is set. Also in this example, as in the example of (a), the possibility that copper as the second metal contacts the electrolytic solution is reduced. This example is particularly effective when corrosion due to the outside air hardly occurs.

The example of FIG. 9D is obtained by reversing the direction of the interface 63 in the example of FIG. 9A, and the entire length direction of the interface 63 is also covered with the resin layer 41 at the side edges 2c and 2d. In addition,

boundary lines

106 and 107 of the resin layer 41 are set. In this embodiment, by crushing the side edges 2c and 2d, the possibility of corrosion by outside air is reduced. Even if crushing is not complete, the substantial surface area can be reduced.

Although the example in which the present invention is applied to the positive electrode terminal 2 has been described above, the present invention can be applied to the negative electrode terminal 3 in exactly the same manner. FIG. 10 shows several examples in which the present invention is applied to the negative electrode terminal 3. FIG. 10 shows each example in a base material state in which the

edges

102 and 103 of the side edges 3c and 3d are not crushed, as in FIG. In the case of the negative electrode terminal 3, for example, the negative electrode terminal 3 is made of a plate-like clad material in which copper as the first metal and aluminum as the second metal are integrally joined, and the negative electrode current collector 22 is formed inside the exterior body 5. The one end portion 3a in the length direction to be connected is constituted by the first metal portion 61 made of copper, and the other end portion 3b in the length direction led out from the exterior body 5 to the outside is made of the second metal portion 62 made of aluminum. Consists of. The negative electrode terminal 3 using such a clad material can be used in combination with, for example, the positive electrode terminal 2 made entirely of aluminum, whereby the portions led out of both

terminals

2 and 3 are made of the same aluminum. It can be a material.

In the example of FIG. 10A, the top 63c of the interface 63 extends toward the first metal portion 61 side made of copper. The boundary lines 106 and 107 of the resin layer 41 are set so that the entire length of the interface 63 is also covered with the resin layer 41 at the side edges 3c and 3d. In this embodiment, the side surface 101 is crushed and the exposed position of the second metal on the side edges 3c and 3d (the portion that is not crushed) is shifted, and in particular, the speed at which aluminum as the second metal contacts the electrolyte. Becomes slower.

In the example of FIG. 10B, the direction of the interface 63 is reversed as compared with the example of FIG. 10A, and exposure from the resin covering the top 63c side of the V-shaped interface 63 is allowed. In this example,

boundary lines

106 and 107 are set. In other words, in this example, the

boundary lines

106, 106 are formed so that the margin between the boundary line 106 and the interface 63 is larger on the first metal portion 61 side where the electrolytic solution is present than the resin layer 41 having the length L. A relative positional relationship between 107 and the interface 63 is set. In the side edges 3c and 3d, the end portion of the interface 63 is exposed to the outside air. However, the side edges 3c and 3d are crushed in the thickness direction to suppress the corrosion of the interface 63 due to the outside air.

The example of FIG. 10C has the same interface 63 direction as FIG. 10A, and the boundary line is allowed to allow the start point 63a and end point 63b side of the interface 63 to be exposed from the resin layer 41. 106 and 107 are set. Also in this example, similarly to the example of FIG. 10A, the possibility that the second metal, aluminum, comes into contact with the electrolytic solution is reduced. This example is particularly effective when corrosion at the interface 63 due to the outside air hardly occurs.

The example of FIG. 10D is obtained by reversing the direction of the interface 63 in the example of FIG. 10A, and the entire length direction of the interface 63 is also covered with the resin layer 41 at the side edges 3c and 3d. As shown, the

boundary lines

106 and 107 of the resin layer 41 are set. In this embodiment, the side surface 101 is crushed, and the possibility of corrosion by outside air at the side edges 3c and 3d is reduced.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications can be made. For example, in the above embodiment, copper and aluminum are used as the metal material of the clad material, but other metal materials can also be used. Moreover, in the film-clad battery 1 illustrated in FIGS. 1 and 2, the pair of

terminals

2 and 3 are arranged side by side on one end edge of the outer package 5, but the positive electrode terminal 2 is arranged on one end edge. However, the present invention can be similarly applied to a battery having a configuration in which the negative electrode terminal 3 is disposed on the other edge.

Claims

In a battery terminal comprising a plate-like clad material in which a first metal constituting one end in the length direction and a second metal constituting the other end are joined via an interface extending in the width direction,
The interface is shaped as a cross-section along the length direction of the terminal, and is longer than the start point appearing on one main surface of the terminal, the end point appearing on the other main surface, and the positions of these start and end points. At least one apex in the middle in the thickness direction that is offset to one of the directions,
A battery terminal in which a side edge portion of a terminal where both ends of an interface extending in the width direction are located is crushed in a thickness direction.
In a battery terminal comprising a plate-like clad material in which a first metal constituting one end in the length direction and a second metal constituting the other end are joined via an interface extending in the width direction,
The interface is shaped as a cross-section along the length direction of the terminal, and is longer than the start point appearing on one main surface of the terminal, the end point appearing on the other main surface, and the positions of these start and end points. At least one apex in the middle in the thickness direction that is offset to one of the directions,
At the side edge of the terminal where both ends of the interface extending in the width direction are located, the first piece extending from the start point to the top and the second piece extending from the end point to the top converge in the thickness direction. The battery terminal.
3. The battery terminal according to claim 1, wherein the interface has a V shape or a W shape as a cross-sectional shape along the length direction of the terminal.
The battery terminal according to any one of claims 1 to 3, wherein a side edge portion is tapered in a cross section along the width direction of the terminal.
A battery in which a power generation element is housed in a film-like outer package together with an electrolyte, wherein the terminal according to any one of claims 1 to 4 is used for at least one of a positive electrode terminal and a negative electrode terminal, and the length of the terminal A battery in which a resin layer is provided in a part of the direction, and the film-shaped outer package is bonded on the resin layer.