JP6342192B2 - Negative electrode terminal for battery and manufacturing method thereof - Google Patents

Description

  The present invention relates to a negative electrode terminal for a battery using a clad material and a manufacturing method thereof.

  Patent Document 1 discloses that in a film-clad battery such as a lithium ion battery, a negative electrode terminal is formed from a clad material obtained by bonding copper and a second metal (for example, nickel). That is, since the negative electrode current collector in the power generation element is generally made of copper, the inner end connected to the negative electrode current collector is made of copper, while the outer end pulled out to the outside is connected to an external terminal or It is made of a dissimilar metal selected in consideration of connection with a bus bar or the like, for example, nickel. And in patent document 1, the interface is formed in the step shape, and the outer edge part becomes a structure by which 2 types of metals were laminated | stacked on the thickness direction.

  Patent Document 2 discloses that a negative electrode terminal is formed of copper and a nickel plating layer is provided on the surface thereof.

JP 2001-126709 A JP 2009-99527 A

  In a terminal using a clad material, in order to ensure a high bonding strength between the two metal parts, the interface between the two is made a simple plane (typically a plane perpendicular to the length direction of the terminal). Instead, as exemplified in Patent Document 1, 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. Therefore, when a plating process is performed in the range from the vicinity of the boundary of the main surface to one side in the length direction so as to provide a nickel plating layer on the surface of the copper portion of the clad material, it spreads from the boundary position of the main surface in the terminal length direction. In addition, the surface of the second metal may come into contact with the plating bath and damage the second metal.

The present invention comprises a plate-like clad material in which copper constituting one end portion in the length direction and a second metal constituting the other end portion are joined via an interface extending in the width direction, and the one end portion is In the negative electrode terminal for the battery connected to the negative electrode current collector of the power generation element and the other end portion led out from the exterior body,
The interface has a shape in a cross section along the length direction of the terminal, a main surface boundary appearing on the two main surfaces of the terminal, and the one end side in the length direction from the position of both main surface boundaries And at least one top in the thickness-wise intermediate portion located,
In the side edge portion of the terminal where both ends of the interface extending in the width direction are located, the copper material near the main surface covers at least partially the second metal by crushing in the thickness direction,
A nickel plating layer is provided on the surface of the copper portion.

  That is, in the present invention, the interface has a three-dimensional shape having one or a plurality of apexes, such as a V shape or a W shape, as a shape seen in a cross section along the terminal length direction. In particular, the top portion enters the copper material side from the main surface boundary. And, at the side edge portion of the terminal where both ends of the interface extending in the terminal width direction are located, the interface that has spread in the thickness direction is crushed so as to approach one linear shape, and the main surface Nearby copper materials gather near the center in the thickness direction and cover the surface of the second metal.

  Therefore, the surface area of the second metal exposed at the side edge portion of the terminal near the main surface boundary is reduced.

  According to the present invention, in the negative electrode terminal for a battery made of a clad material having a three-dimensional interface, the exposed area of the second metal at the terminal side edge caused by the three-dimensional shape can be reduced. The damage of the second metal due to the plating bath during the nickel plating process on the surface of the metal can be suppressed.

The perspective view which shows an example of the film-clad battery provided with the negative electrode terminal of this invention. Sectional drawing of a film exterior battery similarly. The perspective view which shows one Example of the negative electrode terminal which concerns on this invention. The longitudinal cross-sectional view of this negative electrode terminal. FIG. 5 is a cross-sectional view taken along line AA in FIG. 4. The perspective view of the negative electrode 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 a plating process process.

  Hereinafter, an embodiment in which the present invention is applied to a negative electrode terminal of a film-clad battery will be described in detail with reference to the drawings.

  First, an example of a film-clad battery 1 in which the negative electrode terminal according to the present invention is used will be described with reference to FIGS. 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 generation 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 generating element 4 together with the electrolytic solution is a three-layered flexible structure including a heat sealing layer 51, a metal layer 52, and a protective layer 53, as shown in a partially enlarged view in FIG. 2. It consists of a laminate film having properties. 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 is good also as a 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 to 5 show an embodiment of the negative electrode terminal 3 according to the present invention. 3 is a perspective view schematically showing the external appearance of the negative electrode terminal 3, FIG. 4 is a longitudinal sectional view in a cross section along the length direction of the negative electrode terminal 3, and FIG. 5 is a line AA in FIG. FIG. The negative electrode terminal 3 is composed of a plate-like clad material in which copper as a first metal and aluminum as a second metal are integrally joined, and the negative electrode current collector 22 is formed inside the exterior body 5. One end portion 3 a in the length direction connected to the copper plate 61 is constituted by a copper portion 61, and the other end portion 3 b in the length direction led out from the exterior body 5 to the outside is constituted by an aluminum portion 62. In this specification, the x direction in FIG. 4, which is a direction parallel to the lead-out direction of the negative electrode terminal 3, is referred to as the “length direction” of the negative electrode terminal 3, and the y direction in FIG. 3 is referred to as “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 FIGS. 4 and 5 is referred to as the “thickness direction” of the negative electrode terminal 3.

  The interface 63 between the copper portion 61 and the aluminum portion 62 exists in the intermediate portion in the length direction of the negative electrode terminal 3, and the one end portion 3 a of the negative electrode terminal 3 is entirely composed of the copper portion 61 in the thickness direction, The other end portion 3 b is entirely composed of an aluminum portion 62 in the thickness direction. By using such a clad material, the one end 3a is made a material suitable for joining to the negative electrode current collector 22, and the other end 3b is made a material suitable for joining to an external terminal, a bus bar or the like. Therefore, the resistance can be reduced.

  Although the interface 63 extends linearly over the entire width direction of the negative electrode terminal 3, 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. 6 and a solid interface 63 having a substantially V-shaped cross section as shown in FIG.

  In other words, the interface 63 in this embodiment has a shape appearing in the longitudinal section along the length direction of the negative electrode terminal 3 in FIG. 4, and is intermediate in the thickness direction from the main surface boundary 63 a appearing on the first main surface 64 a of the negative electrode terminal 3. The first piece 631 that extends obliquely toward the portion and the second piece 632 that extends obliquely from the main surface boundary 63b appearing on the second main surface 64b of the negative electrode terminal 3 toward the intermediate 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, when viewed in the length direction of the negative electrode terminal 3, the position of one main surface boundary 63a appearing linearly on the first main surface 64a and the position of the other main surface boundary 63b appearing linearly on the second main surface 64b. Are basically the same positions, and the V-shaped top portion 63c is located closer to the one end portion 3a of the negative electrode terminal 3 than these positions. That is, the top 63c extends so as to enter the copper portion 61 from the positions of the main surface boundaries 63a and 63b.

  The interface 63 may have a cross-sectional shape close to a U shape, or may have a cross-sectional shape such as a W 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 3c and 3d of the negative electrode terminal 3. On the other hand, the side edges 3c and 3d of the negative electrode terminal 3 are formed in a tapered shape that is crushed from both sides in the thickness direction as shown in FIGS. The one piece 631 and the second piece 632 are gradually converged in the thickness direction.

  That is, as shown in FIG. 6, the base material of the clad material in which two kinds of metals are joined is such that the interface 63 having a V-shaped cross section continues 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 from both sides in a taper shape in the thickness direction of the terminals 2 and 3, so that a pair of tapered surfaces 104 and 105 ( 3 and 5) are formed.

  Along with the plastic deformation of the base material, the first piece 631 and the second piece 632 of the interface 63 converge in the thickness direction, and at the same time, exist in a triangle along the edges 102 and 103 in the base material state. Since the material of the copper portion 61 (the copper material indicated by reference numeral 61a in FIG. 6) was collected from both sides at the center in the thickness direction, the surface of the aluminum portion 62 that existed in a V shape on the base material side surface 101 (A region indicated by reference numeral 62a in FIG. 6) is covered with this copper material. Ideally, the interface 63 appearing on the side edges 3c and 3d is a single straight line, and the exposed surface (region 62a) of the aluminum portion 62 existing in the V shape substantially disappears (see FIG. 3), however, even if crushing is not complete, the exposed area of the aluminum material is greatly reduced.

  For example, the negative electrode terminal 3 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. 3c and 3d 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 3c and 3d can be performed simultaneously with the cutting of the side edges 3c and 3d.

  A nickel plating layer 71 is provided on the surface of the copper portion 61 by electrolytic plating. The plating process for the nickel plating layer 71 is performed after the processing of the side edges 3c and 3d of the base material, and the nickel is disposed in the range from the vicinity of the main surface boundaries 63a and 63b of the interface 63 to the one end 3a side. A plating layer 71 is provided. For example, as illustrated in FIG. 8, the plating process is performed in a state where the liquid surface 122a of the plating bath 122 in the plating apparatus 121 is located in the vicinity of the main surface boundaries 63a and 63b.

  During the plating process, in the negative electrode terminal 3 of the above embodiment, the side edges 3c and 3d are crushed from both sides as described above so that the aluminum material in the region 62a on the base material side surface 101 is covered with the copper material. Therefore, the aluminum material does not touch the plating bath 122. Even if the crushing is not complete, the exposed area of the aluminum material in the region 62a is greatly reduced. Therefore, damage to the aluminum material due to the plating bath 122 is suppressed, and defective plating (peeling due to poor adhesion between copper and the plating layer) is suppressed.

  The resin layer 41 shown in FIG. 2 is provided on the surface of the negative electrode terminal 3 by an appropriate method such as application of a resin material or adhesion of a resin film after the plating treatment of the nickel plating layer 71. In the example of FIG. 3, the resin layer 41 is provided in a range of a length L between the boundary lines 106 and 107 so as to cover the main surface boundaries 63a and 63b appearing on the main surfaces 64a and 64b.

  As mentioned above, although one Example of this invention was described, this invention is not limited to the said Example, A various change is possible. For example, in the above embodiment, aluminum is used as the second metal of the cladding material, but other metals can also be used. Moreover, although the example of electrolytic plating was demonstrated in the said Example, electroless plating may be sufficient.

DESCRIPTION OF SYMBOLS 1 ... Film-clad battery 3 ... Negative electrode terminal 4 ... Power generation element 5 ... Exterior body 22 ... Negative electrode collector 41 ... Resin layer 61 ... Copper part 62 ... Aluminum part 63 ... Interface 71 ... Nickel plating layer

Claims (5)

It consists of a plate-like clad material in which copper 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, and the one end is the negative electrode of the power generation element In the negative electrode terminal for a battery that is connected to the current collector and the other end is led out from the exterior body,
The interface has a shape in a cross section along the length direction of the terminal, a main surface boundary appearing on the two main surfaces of the terminal, and the one end side in the length direction from the position of both main surface boundaries And at least one top in the thickness-wise intermediate portion located,
In the side edge portion of the terminal where both ends of the interface extending in the width direction are located, the copper material near the main surface covers at least partially the second metal by crushing in the thickness direction,
A negative electrode terminal for a battery, in which a nickel plating layer is provided on the surface of the copper portion.   The negative electrode terminal for a battery according to claim 1, wherein the second metal is aluminum, and the nickel plating layer is formed by electrolytic plating.   The negative electrode terminal for a battery according to claim 1, wherein the interface has a V shape or a W shape as a shape in a cross section along the length direction of the terminal.   The negative electrode terminal for a battery 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. It consists of a plate-like clad material in which copper 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, and the one end is the negative electrode of the power generation element A method of manufacturing a battery negative electrode terminal connected to a current collector and having the other end portion led out from an exterior body,
The shape of the interface on the cross section along the length direction of the terminal is located on the main surface boundary appearing on the two main surfaces of the terminal, and offset from the position of both main surface boundaries toward the one end in the length direction. The clad material is configured so as to have a three-dimensional shape having at least one top portion in the thickness direction intermediate portion,
The side edge portion of the terminal where both ends of the interface extending in the width direction are crushed in the thickness direction so as to be tapered,
A method of manufacturing a negative electrode terminal for a battery, wherein a nickel plating layer is plated on the surface of the copper portion.

Images