JP2017098022A - Separator welding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress poor welding.SOLUTION: A separator welding device 70 includes an upper mold 71 and a lower mold 81 arranged oppositely in the vertical direction. The upper mold 71 is movable toward the lower mold 81. The upper mold 71 includes a heater 72 of such a shape as projecting toward the lower mold 81. The lower mold 81 includes a thermally conductive cushion material 82 projecting toward the upper mold 71. The thermally conductive cushion material 82 has the same shape as the heater 72. The lower mold 81 includes a cushion heating part 84 for heating the thermally conductive cushion material 82.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a separator welding apparatus.

  A vehicle such as an EV (Electric Vehicle) or a PHV (Plug in Hybrid Vehicle) is equipped with a secondary battery such as a lithium ion battery as a power storage device that stores power supplied to an electric motor serving as a prime mover. The secondary battery includes, for example, an electrode assembly in which a positive electrode and a negative electrode are stacked with a separator interposed therebetween.

  In some electrode assemblies, either one of the electrodes is accommodated by a bag-like separator. Such an electrode storage separator is manufactured by, for example, welding a portion surrounding the electrodes of the separator materials in a state where the electrodes are sandwiched between a pair of long strip-shaped separator materials, and thereafter, the pair of separator materials is bonded to the separator. It may be done by cutting into shapes.

  As a welding apparatus for welding the separator material, an apparatus that welds a pair of separator materials sandwiched from the overlapping direction is known. As this kind of welding apparatus, it describes in patent document 1, for example. In the electric heat sealing apparatus of Patent Document 1, a heater is provided on the machine base, and a pressing pad made of silicon rubber is provided on a swinging body that can swing with respect to the machine base. The heater and the pressing pad can be in contact with each other by the swinging of the swinging body. When the separator material is welded using such a heat seal device, the pair of separator materials are sandwiched between the heater and the pressing pad, and the separator materials are welded together by heat applied to the separator material from the heater.

JP-A-3-133722

  By the way, when the temperature of the separator material does not reach a temperature suitable for welding at the timing when the separator material is sandwiched between the heater and the pressing pad, poor welding occurs. For example, when the pressing pad is not heated to a temperature suitable for welding, such as immediately after the welding of the separator material is started, poor welding is likely to occur.

  An object of the present invention is to provide a separator welding apparatus that can suppress poor welding.

  A separator welding apparatus that solves the above-described problem is a separator welding apparatus that welds separator materials provided with electrodes interposed therebetween, and a heater that heats the separator material, and heat that is pressed against the heater through the separator material. A conductive cushioning material; and a cushion heating unit that heats the thermally conductive cushioning material.

  According to this, the heat conductive cushion material can raise temperature by being heated by the cushion heating part. For this reason, the heat conductive cushion material can be brought to a temperature suitable for welding by the timing when the heater is pressed against the heat conductive cushion material through the separator material. Therefore, when the separator material is sandwiched between the heater and the heat conductive cushion material, poor welding of the separator materials due to the low temperature of the heat conductive cushion material is suppressed. Also, after repeated welding, the temperature of the thermally conductive cushion material rises due to the heat of the heater, but when the separator material starts welding, the thermally conductive cushion material is heated by the heater. Absent. However, even when such welding is started, the heat conductive cushion material is heated by the cushion heating portion, so that poor welding hardly occurs.

  According to the present invention, poor welding can be suppressed.

The perspective view which shows a secondary battery. The disassembled perspective view which shows an electrode assembly. Schematic which shows the manufacturing apparatus of an electrode storage separator. The top view which shows the heater provided in the upper mold | type. The perspective view which shows a separator welding apparatus. Sectional drawing which shows a separator welding apparatus. Sectional drawing which shows the separator welding apparatus of the state before welding separator material. Sectional drawing which shows the separator welding apparatus of the state which pinched | interposed the separator material with the heater and the heat conductive cushion material. The top view which shows the heater of a modification.

Hereinafter, an embodiment of a separator welding apparatus will be described.
As shown in FIG. 1, the secondary battery 10 is a lithium ion secondary battery. The secondary battery 10 includes an electrode assembly 20, an electrolyte solution (not shown), a case 28 containing the electrode assembly 20 and the electrolyte solution, and two terminals 29 for transferring electricity to and from the electrode assembly 20. Is provided.

  As shown in FIG. 2, the electrode assembly 20 includes a plurality of positive electrodes 21 as electrodes, a plurality of negative electrodes 22, and a plurality of electrode storage separators 26. The electrode assembly 20 is configured by laminating a positive electrode 21 and a negative electrode 22 in a state where they are insulated from each other by an electrode storage separator 26.

  The positive electrode 21 and the negative electrode 22 include a square sheet-like electrode body 24 and a tab 25 having a shape protruding from the first side 24 a of the electrode body 24. The electrode body 24 includes a square sheet-like metal foil 23. The metal foil 23 of the positive electrode 21 is, for example, an aluminum foil. The metal foil 23 of the negative electrode 22 is, for example, a copper foil.

  The tab 25 protrudes from the metal foil 23 of the electrode body 24. The tab 25 of the positive electrode 21 is, for example, an aluminum foil, and the tab 25 of the negative electrode 22 is, for example, a copper foil. The electrode main body 24 of the positive electrode 21 and the negative electrode 22 includes an active material layer 27 on both surfaces of the metal foil 23. The active material layer 27 contains an active material for each polarity, a binder, a conductive aid, and the like.

  In the electrode body 24 of the positive electrode 21, the long side that is the opposite side of the first side 24a where the tab 25 is present is defined as a second side 24b. In addition, in the electrode body 24 of the positive electrode 21, one of the short sides of the pair of sides (short sides) connecting the first side 24a and the second side 24b is the third side 24c, and the other side is the fourth side. 24d.

  The positive electrode 21 is stored in a bag-shaped electrode storage separator 26. The electrode storage separator 26 includes a square sheet-shaped first separator piece 26a and a second separator piece 26b. Each separator piece 26a, 26b is a porous insulator. The tab 25 of the positive electrode 21 protrudes from the edge of the electrode storage separator 26.

  The peripheral edge that protrudes from the edge of the electrode body 24 in the first separator piece 26a and the peripheral edge that protrudes from the edge of the electrode body 24 in the second separator piece 26b are thermally welded to each other. The thermally welded portion becomes the first welding portion 31 to the fourth welding portion 34 surrounding the electrode main body 24 of the positive electrode 21 in the electrode storage separator 26, and is surrounded by the first welding portion 31 to the fourth welding portion 34. The region to be stored is a housing portion for the positive electrode 21.

  The electrode storage separator 26 includes a first welded portion 31 outside the first side 24a along the direction along the surface of the stored positive electrode 21. The first welded portion 31 has a certain width along the first side 24 a of the positive electrode 21. The first welded portion 31 is not provided at a portion overlapping the tab 25. The electrode storage separator 26 includes a second welded portion 32 outside the second side 24b along the direction along the surface of the stored positive electrode 21. The second welded portion 32 has a certain width along the second side 24 b of the positive electrode 21.

  Further, the electrode storage separator 26 includes a third welded portion 33 outside the third side 24 c along the direction along the surface of the stored positive electrode 21. The third welded portion 33 has a certain width along the third side 24 c of the positive electrode 21. The electrode storage separator 26 includes a fourth weld portion 34 outside the fourth side 24d along the direction along the surface of the stored positive electrode 21. The fourth weld portion 34 has a certain width along the fourth side 24 d of the positive electrode 21. Therefore, the electrode housing separator 26 is welded at a portion surrounding the positive electrode 21, and more specifically, a portion of the portion surrounding the electrode body 24 of the positive electrode 21 that does not overlap with the tab 25 is welded. .

Next, an apparatus for manufacturing the electrode storage separator 26 will be described.
As shown in FIG. 3, the apparatus 40 for manufacturing the electrode storage separator 26 is an apparatus for manufacturing the electrode storage separator 26 that stores the positive electrode 21 by welding separator materials 41 that are precursors of the electrode storage separator 26 together. It is.

  The manufacturing apparatus 40 includes a supply device 50 that supplies a long strip-shaped separator material 41. The supply device 50 includes a first supply reel 43 and a second supply reel 44 around which a separator material 41 is wound. The first supply reel 43 is located below the second supply reel 44. The first supply reel 43 and the second supply reel 44 are wound so that the longitudinal direction of the separator material 41 extends in the circumferential direction of the supply reels 43 and 44. The first supply reel 43 and the second supply reel 44 are supported by a driving device (not shown) so as to be able to rotate around their respective axes.

  The first supply reel 43 and the second supply reel 44 supply the separator material 41 so that the surfaces in the thickness direction perpendicular to the longitudinal direction and the short direction of the separator material 41 face each other. The positive electrode 21 is transported between the separator material 41 supplied from the first supply reel 43 and the separator material 41 supplied from the second supply reel 44 by an electrode transport device (not shown).

  The manufacturing apparatus 40 includes a transport device 60 that transports the separator material 41. The transport device 60 includes two transport rolls 61 disposed to face each other with the pair of separator materials 41 interposed therebetween, and two transport rolls 62 disposed to face each other with the pair of separator materials 41 sandwiched therebetween.

  The transport rolls 61 and 62 are supported by a driving device (not shown) so as to be able to rotate around their respective axis centers. The transport roll 61 and the transport roll 62 are disposed at positions sandwiching a separator welding device 70 described later in the longitudinal direction of the separator material 41. A pair of separator materials 41 sandwiching the positive electrode 21 is passed between the first transport rollers 61 and between the second transport rollers 62.

  When the supply device 50 and the transport device 60 are driven, the pair of separator materials 41 sandwiching the positive electrode 21 are transported along the transport direction X1. In addition, among the directions along the surface of the separator material 41, a direction (short direction of the separator material 41) orthogonal to the transport direction X1 is defined as a width direction X2.

  The manufacturing apparatus 40 includes a separator welding device 70 that welds a portion surrounding the positive electrode 21 between the pair of separator materials 41, and a separator material 41 in which the portion surrounding the positive electrode 21 is welded by the separator welding device 70 along the longitudinal direction. And a cutting device 90 for cutting at regular intervals.

  The cutting device 90 includes a cutting blade 91 extending along the width direction X2. The cutting blade 91 cuts the separator material 41 at a predetermined interval by reciprocating at a predetermined cycle. The electrode storage separator 26 is obtained by cutting the separator material 41 with the cutting blade 91. The manufacturing apparatus 40 includes a transport device 92 that transports the electrode storage separator 26, and the electrode storage separator 26 manufactured by cutting with the cutting blade 91 is transported by the transport device 92.

Next, the separator welding apparatus 70 which welds the separator material 41 is demonstrated in detail.
The separator welding device 70 includes an upper mold 71 and a lower mold 81 that are arranged to face each other in the vertical direction (vertical direction). The upper mold 71 is movable toward the lower mold 81 by an actuator (not shown). The pair of separator materials 41 is passed between the upper mold 71 and the lower mold 81.

  As shown in FIGS. 4 and 5, the upper mold 71 includes a heater 72 having a shape protruding toward the lower mold 81. The heater 72 includes a first heating unit 73 and a second heating unit 74 that are parallel to each other. The first heating unit 73 and the second heating unit 74 extend linearly along the transport direction X1. A recess 77 that does not protrude from the lower mold 81 is provided in a part of the first heating unit 73. The recess 77 is a non-heated portion where the separator material 41 is not heated.

  The heater 72 includes a third heating unit 75 and a fourth heating unit 76 that are parallel to each other. The third heating unit 75 and the fourth heating unit 76 extend linearly along the width direction X <b> 2 so as to connect the first heating unit 73 and the second heating unit 74. The heater 72 has a square frame shape by the heating units 73 to 76.

  The dimensions at the inner edges of the first heating unit 73 and the second heating unit 74 along the transport direction X1 are the first welding unit 31 and the second welding unit along the first side 24a and the second side 24b of the electrode body 24. The dimensions at the inner edge of 32 are the same or substantially the same. In addition, the size of the recess 77 of the first heating unit 73 along the transport direction X <b> 1 is equal to or larger than the size of the tab 25 along the longitudinal direction of the electrode body 24.

  The dimensions at the inner edges of the third heating part 75 and the fourth heating part 76 along the width direction X2 are the third welding part 33 and the fourth welding part along the third side 24c and the fourth side 24d of the electrode body 24. It is the same as the dimension in the inner edge of 34, or substantially the same.

Each heating unit 73 to 76 is heated by a heat source (not shown).
The lower mold 81 includes a thermally conductive cushion material 82 having a shape protruding toward the upper mold 71. In the present embodiment, the thermally conductive cushion material 82 has the same shape as the heater 72. More specifically, the thermally conductive cushion material 82 has a rectangular frame shape, and a concave portion 83 that does not protrude toward the upper mold 71 is provided in a part thereof. The heat conductive cushion material 82 is opposed to the heater 72 throughout, and the entire surface of the heater 72 can be opposed to the heat conductive cushion material 82 when the mold is closed. The recess 83 of the thermally conductive cushion material 82 faces the recess 77 of the heater 72.

  The thermally conductive cushion material 82 is manufactured from an elastic material having excellent thermal conductivity. Preferably, an elastic material having a thermal conductivity of 0.1 [W / m · k] or higher is used, and more preferably, an elastic material having a thermal conductivity of 1.0 [W / m · k] or higher is used. As the elastic material, for example, silicon having excellent thermal conductivity or rubber such as fluorine can be used.

  As shown in FIG. 6, the lower mold 81 includes a cushion heating unit 84 that heats the thermally conductive cushion material 82. The cushion heating unit 84 is provided below the thermally conductive cushion material 82. In the present embodiment, the cushion heating unit 84 is provided in a state of covering the entire thermally conductive cushion material 82 from below. In addition, as the cushion heating part 84, the heating apparatus which heats the heat conductive cushion material 82 with Joule heat is used, for example.

Next, the effect | action of the separator welding apparatus 70 of this embodiment and the manufacturing method of the electrode storage separator 26 are demonstrated.
When manufacturing the electrode storage separator 26, a pair of separator material 41 is conveyed along the conveyance direction X1 with the positive electrode 21 sandwiched therebetween. As shown in FIG. 7, in the supply device 50 and the conveyance device 60, the electrode body 24 of the positive electrode 21 sandwiched between the separator materials 41 is positioned within the frame of the thermally conductive cushion material 82 in a plan view. The separator material 41 is conveyed so that the separator material 41 stops at a position where the tab 25 is located in the recess 83.

  As shown in FIG. 8, the separator welding device 70 moves the upper mold 71 toward the lower mold 81. As a result, the heater 72 of the upper mold 71 is pressed against the heat conductive cushion material 82 via the separator material 41, and the region surrounding the positive electrode 21 of the pair of separator materials 41 is sandwiched between the heater 72 and the heat conductive cushion material 82. It is. The cushion heating unit 84 heats the heat conductive cushion material 82 in advance before the pair of separator materials 41 is sandwiched between the heater 72 and the heat conductive cushion material 82. Therefore, the separator material 41 is heated and welded from both the upper and lower sides by the heater 72 and the heat conductive cushion material 82.

  In the pair of separator materials 41, the first welded portion 31 is formed at a site heated by the first heating unit 73, and the second welded portion 32 is formed at a site heated by the second heating unit 74. Further, in the pair of separator materials 41, the third welded portion 33 is formed at the portion heated by the third heating portion 75, and the fourth welded portion 34 is formed at the portion heated by the fourth heating portion 76. The

  Separator welding device 70 moves upper die 71 away from lower die 81 when a predetermined heating time has elapsed. And the supply apparatus 50 and the conveying apparatus 60 convey the separator material 41 along the conveyance direction X1. Separator material 41 having a portion surrounding positive electrode 21 welded by separator welding device 70 is cut by cutting device 90. In the present embodiment, the pair of separator materials 41 is cut along the width direction X2 and divided in the transport direction X1. Thereby, the electrode storage separator 26 of a predetermined shape can be obtained.

Therefore, according to the above embodiment, the following effects can be obtained.
(1) The separator welding device 70 includes a heater 72 and a thermally conductive cushion material 82 that are welded with the separator material 41 interposed therebetween. Since the separator welding device 70 further includes a cushion heating unit 84 that heats the heat conductive cushion material 82, when the separator material 41 is welded, the heat conductive cushion material 82 is preheated by the cushion heating unit 84. Can do. Therefore, for example, even immediately after the start of welding, the heat conductive cushion material 82 can be heated by the cushion heating unit 84 to make the temperature of the heat conductive cushion material 82 suitable for welding. Therefore, the separator material 41 can be heated from the upper and lower sides at a temperature suitable for welding, and poor welding can be suppressed.

  (2) The separator material 41 is sandwiched and welded by the heater 72 and the heat conductive cushion material 82. The heat conductive cushion material 82 is elastically deformed following the shape of the heater 72 when the heater 72 is pressed, and the entire portion sandwiched between the heater 72 and the heat conductive cushion material 82 is easily heated. When the separator material 41 is sandwiched between the heaters, both heaters are less likely to be elastically deformed, and a portion that is easily heated and a portion that is difficult to be heated are generated, which contributes to poor welding. By performing this, it is possible to suppress welding defects.

  (3) A cushion heating unit 84 is provided below the thermally conductive cushion material 82. Since heat is likely to be applied upward, the heat conductive cushioning material 82 is easily heated, and poor welding can be further suppressed.

  (4) Heat is also applied to the separator material 41 from the thermally conductive cushion material 82 heated by the cushion heating unit 84. For this reason, compared with the case where the cushion heating part 84 is not provided, the amount of heat applied to the separator material 41 increases, and the temperature of the separator material 41 easily reaches the temperature required for welding. For this reason, the time required for welding the separator material 41 can be shortened, and the productivity of the electrode storage separator 26 can be improved.

  (5) By heating the thermally conductive cushion material 82 by the cushion heating unit 84, it is possible to suppress welding failure while suppressing the heating time of the separator material 41 by the heater 72 from being increased. If the heating time of the separator material 41 by the heater 72 is lengthened in order to suppress poor welding, the separator material 41 may be excessively heated, and problems such as adhesion of the molten separator material 41 to the heater 72 may occur. Since the heating time is prevented from becoming long, the separator material 41 is hardly heated excessively.

In addition, you may change embodiment as follows.
In the embodiment, the heater 72 has a configuration in which the four heating units 73 to 76 are connected in a frame shape, but is not limited thereto. The separator welding apparatus in FIG. 9 includes two upper molds 101 and 102. One upper mold 101 is provided with a third heating unit 75 and a fourth heating unit 76 that weld the separator material 41 in the width direction X2. The other upper mold 102 is provided with a first heating unit 73 and a second heating unit 74 for welding the separator material 41 in the transport direction X1. Although not shown, the separator welding apparatus includes two lower molds corresponding to the upper molds 101 and 102, and one lower mold has the same heat conduction as the third heating unit 75 and the fourth heating unit 76. The other lower mold is provided with a heat conductive cushion material having the same shape as the first heating unit 73 and the second heating unit 74. And each lower mold | type is provided with the cushion heating part which heats a heat conductive cushion material. In FIG. 9, the two upper molds 101 and 102 are provided with separate heating units, but separate heating units may be provided at different locations of one upper mold.

  -Only one heating part which welds the separator material 41 along the width direction X2 may be sufficient. That is, the separator welding device may be configured to include only one of the third heating unit 75 and the fourth heating unit 76. In this case, the electrode storage separator manufactured adjacent to the transport direction X1 by dividing the welded portion formed by the heating unit that welds the separator material 41 along the width direction X2 into the transport direction X1 by the cutting device 90. 26, a third welded portion 33 of one electrode storage separator 26 and a fourth welded portion 34 of the other electrode storage separator 26 are formed.

A heat conductive cushion material 82 and a cushion heating unit 84 may be provided on the upper mold 71, and a heater 72 may be provided on the lower mold 81.
A heater 72 may be provided on one of a pair of rollers provided with a pair of separator materials 41 interposed therebetween, and a heat conductive cushion material 82 and a cushion heating unit 84 may be provided on the other. More specifically, a heater 72 having a shape protruding in the radial direction of the roller is provided on the outer peripheral surface of one roller, and a heat conductive cushion material 82 sandwiching a pair of separator materials 41 together with the heater 72 is provided on the outer peripheral surface of the other roller. It may be provided. The cushion heating unit 84 is provided, for example, on the radially inner side of the roller with respect to the thermally conductive cushion material 82.

  The heat conductive cushion material 82 may be a shape different from the heater 72 as long as it can sandwich the pair of separator materials 41 together with the heater 72. For example, the shape may be smaller than the heater 72 or larger.

The cushion heating part 84 should just be able to heat the heat conductive cushion material 82, and may be provided so that a part of heat conductive cushion material 82 may be covered.
The cushion heating unit 84 may be provided adjacent to the heat conductive cushion material 82 in the horizontal direction.

The separator welding device 70 may be used for welding a separator material used for a power storage device other than a secondary battery, such as a capacitor.
A heat conductive cushion material may be provided below the heater 72 so that the separator material 41 is sandwiched between the heat conductive cushion materials. In this case, the pair of separator materials 41 are heated and welded by the heat conductive cushion material heated by the heater 72 and the heat conductive cushion material 82 heated by the cushion heating unit 84.

The electrode storage separator 26 may store the negative electrode 22.
The cushion heating unit 84 may continuously heat the thermally conductive cushion material 82 while the separator welding device 70 is being driven, or the thermal conductive cushion so as to hinder the welding of the separator material 41. The heat conductive cushion material 82 may be intermittently heated within a range where the temperature of the material 82 does not decrease.

  When the separator material 41 is welded, the lower die 81 may move toward the upper die 71, or the upper die 71 and the lower die 81 may move so as to approach each other. The state in which the heater 72 is pressed against the heat conductive cushion material 82 via the separator material 41 is a state in which the heater 72 is moved toward the heat conductive cushion material 82 and the heater 72 is pressed. However, the present invention includes a state in which the heat conductive cushion material 82 moves toward the heater 72 and the heat conductive cushion material 82 is pressed against the heater 72. Even in this case, the pressing force from the heater 72 is applied to the heat conductive cushion material 82 through the separator material 41. Therefore, when the separator material 41 is sandwiched between the heater 72 and the heat conductive cushion material 82, the heat conductive cushion material 82 has no relation to which of the heater 72 and the heat conductive cushion material 82 has moved. The heater 72 is pressed.

In place of the recess 77, a member that does not melt the portion overlapping the tab 25 of the separator material 41 (such as a member having low thermal conductivity) may be provided as a non-heated portion.
-Separator material is not restricted to a elongate strip | belt shape, The thing processed into the shape of the electrode storage separator 26 previously may be sufficient.

Next, the technical idea that can be grasped from the embodiment and the modified examples will be described below.
(A) The thermal conductive cushion material is made of an elastic material having a thermal conductivity of 0.1 [W / m · k] or more.

(B) The thermal conductive cushion material is made of an elastic material having a thermal conductivity of 1.0 [W / m · k] or more.
(C) The elastic material is silicon.

  (D) A structure in which separator materials provided on both sides of electrodes are welded to each other, and is a method for manufacturing an electrode storage separator in which the electrodes are stored inside, and a thermally conductive cushion material heated by a cushion heating unit; The manufacturing method of the electrode storage separator which sandwiches and welds the said separator materials with a heater.

  DESCRIPTION OF SYMBOLS 21 ... Positive electrode, 22 ... Negative electrode, 41 ... Separator material, 70 ... Separator welding apparatus, 72 ... Heater, 82 ... Thermally conductive cushion material, 84 ... Cushion heating part.

Claims (1)

A separator welding device for welding separator materials provided with electrodes sandwiched therebetween,
A heater for heating the separator material;
A thermally conductive cushion material against which the heater is pressed through the separator material;
A separator welding apparatus comprising: a cushion heating unit that heats the thermally conductive cushion material.