JP6019224B2 - Manufacturing method and manufacturing apparatus for laminate type secondary battery - Google Patents

Description

  The present invention relates to a method and an apparatus for manufacturing a secondary battery called a laminate type or a thin type.

  In a laminated pack type (thin type) secondary battery represented by a lithium ion secondary battery, a laminate type in which a battery element (power generation element) including a positive electrode, a negative electrode, and an electrolyte as electrodes is used as an exterior body. The lead terminals surrounded by the outer film and electrically connected to the current collectors of the positive electrode and the negative electrode are led out of the outer film, and the peripheral edge of the outer film is formed into, for example, a rectangular bag by heat welding. Sealing or sealing treatment is performed to ensure airtightness as a battery and prevent leakage of the electrolyte inside. In addition, as the said exterior film, the thing of the structure which coat | covered the front and back both surfaces of the aluminum foil with the resin film, for example is used.

  As a specific means for performing heat welding on the exterior film, for example, as described in Patent Document 1, a so-called hot plate type pressure treatment that is always heated by incorporating a heat transfer heater is used. The outer peripheral film is sandwiched from both the front and back surfaces by the pressure jig, and heat welding is performed.

  When heat-sealing the outer film of the secondary battery as described above, when focusing on the side portion where the lead terminal of the electrode is led out, the outer film and the lead terminal are heated in the portion where the lead terminal of the electrode is led out. While it will be welded, the exterior films will be thermally welded in other parts, and the behavior of heat transfer will be different between them, so just pressing the pressure jig that is always heated Thermal welding failure or sealing failure is likely to occur at the lead terminal portion. This is considered to be caused by the fact that the heat for heat welding is excessively transferred to the lead terminal itself in the portion where the lead terminal is led out, and the temperature of the portion actually involved in the welding is lowered. .

JP 2001-76690 A

  The present invention has been made paying attention to such a problem, and in particular, when performing thermal welding on the side portion of the exterior film from which the lead terminal is led out, by making the welding temperature uniform, it is possible to prevent thermal welding failure. It is intended to suppress the occurrence.

Therefore, in the present invention, in applying heat welding by pressing and restraining the peripheral portion of the exterior film with a heat welding jig provided with a heater on the contact surface side with the exterior film, in the portion corresponding to the terminal portion of the electrode, , heat welding and facilities while interposing a heat insulating material between the jig body and the heater of the heat welding jig, in a portion other than the portion corresponding to the terminal portions of the electrodes, the thermal welding jig jig body and it is obtained by heat welding to the facilities Suyo with no interposed insulation between the heater.

  According to the present invention, due to the heat insulating effect of the heat insulating material, the welding temperature can be made uniform between the portion where the terminal portion of the electrode is led out and the portion where the electrode terminal portion is not, and the occurrence of poor heat welding can be suppressed. A highly reliable sealing or sealing process can be performed on the exterior film of the secondary battery.

1 is a perspective view showing a schematic structure of a laminated lithium ion secondary battery applied to the practice of the present invention. FIG. 2 is an exploded perspective view of the laminated lithium ion secondary battery shown in FIG. 1. The figure which shows a heat welding apparatus as embodiment of the manufacturing apparatus of the lamination type secondary battery which concerns on this invention, and is expanded sectional explanatory drawing along the AA of FIG. It is the figure which expanded the left half part of FIG. 3, (A) is sectional drawing which shows the state from which the upper and lower heat welding jigs have separated, (B) is the upper and lower heat welding jigs approaching, and laminated film Sectional drawing which shows the state restrained by pressure. The expanded sectional view along the BB line of (B) of FIG. The expanded sectional view along CC line of (B) of FIG.

  FIGS. 1-6 shows the more concrete form for implementing the manufacturing method of the lamination type secondary battery which concerns on this invention, and especially FIG. 1 shows a lithium ion secondary battery (henceforth, following) as an example of a lamination type secondary battery. FIG. 2 shows an exploded perspective view of the schematic structure of the battery. This battery is used, for example, as a unit cell or a single battery of a lithium ion battery for an electric vehicle.

  As shown in FIGS. 1 and 2, in the battery 1, a lead terminal (positive electrode terminal portion) 2 as a positive electrode terminal and a lead terminal (negative electrode portion) 3 as a negative electrode terminal are led out to the outside. In this state, the film is housed and sealed by a rectangular laminated film outer package 4 composed of two upper and lower laminated films 4a and 4b as an outer film. In the laminate film outer package 4, a laminated body 5 formed by laminating a plurality of sets of positive electrodes and negative electrodes as electrodes serving as battery elements (power generation elements) and separators interposed between them is accommodated together with the electrolyte. In addition, the four circumferences of the laminate film outer package 4 are hermetically sealed or sealed by heat welding. The four-round heat welded portion is denoted by reference numeral 6.

  That is, in the battery 1 shown in FIGS. 1 and 2, a battery element including a positive electrode and a negative electrode as electrodes, a separator, and an electrolyte solution is surrounded by a laminate film outer package 4, and each positive electrode and negative electrode current collector is enclosed. The lead terminals 2 and 3 that are electrically connected are led out to the outside of the laminate film outer package 4, and the periphery of the laminate film outer package 4 is sealed or sealed in a rectangular bag shape by thermal welding, for example. As a result, the airtightness of the battery 1 is secured. As the two upper and lower laminate films 4a and 4b forming the laminate film outer package 4, for example, a composite structure in which both front and back surfaces of an aluminum foil are covered with a heat-welding resin film is used.

  Then, both the lead terminal 2 on the positive electrode side and the lead terminal 3 on the negative electrode side are led out from one common side of the rectangular laminated film outer package 4 to the outside. In this case, both the lead terminals 2 and 3 are sometimes referred to as electrode tabs, and the positive lead terminal 2 is made of aluminum, for example, while the negative lead terminal 3 is Copper one is used. Both lead terminals 2 and 3 are preliminarily subjected to a predetermined surface treatment, and are covered with a resin layer 7 (see FIG. 4) having heat welding properties and insulation properties.

  The four sides of the rectangular laminate film outer package 4 are welded by, for example, several steps using a heat welding apparatus, and FIG. 3 shows an enlarged cross-sectional view taken along line AA of FIG. FIG. 4 shows an enlarged view of the portion corresponding to the lead terminal 2 on the positive electrode side in the left half of FIG. 5 and 6 are enlarged sectional views taken along lines AA and BB in FIG.

  As is apparent from FIGS. 5 and 6, the overlapping portions of the plurality of positive electrodes 8 forming a part of the laminate 5 in FIG. It is connected to the terminal 2 by welding. This structure is basically the same for the relationship between the negative electrode and the lead terminal 3 on the negative electrode side, and these structures are not shown in FIG.

  As shown in FIG. 4, the thermal welding apparatus is mainly configured by a lower thermal welding jig 9 and an upper thermal welding jig 10 which are arranged to face each other so as to be close to and away from each other. Both of the heat welding jigs 9 and 10 are made of, for example, stainless steel, and a portion that performs heat welding extends in the longitudinal direction of the heat welding portion 6 (see FIG. 1) of the laminate film exterior body 4 in a plan view. As shown in FIGS. 5 and 6, the width dimension is set to be slightly larger than the width dimension of the heat-welded portion 6 of the laminate film outer package 4.

  As shown in FIG. 4B, the upper and lower laminate films 4a and 4b to be the laminate film outer package 4 surrounding the laminate 5 in FIG. 2 are supported by a support member (not shown). The lower thermal welding jig 9 and the upper thermal welding jig 10 are moved closer to each other, and the upper and lower laminate films 4a and 4b are pressure-restrained from above and below to apply the thermal welding to the corresponding part. Thus, the laminate film exterior body 4 is finished.

  Here, as is apparent from FIG. 4, the portion between the upper and lower laminate films 4 a and 4 b of the laminate film outer package 4 between the upper and lower laminate films 4 a and 4 b is directly welded. Since the positive lead terminal 2 is interposed and the laminate films 4a and 4b and the positive lead terminal 2 are thermally welded to each other, the thickness is inevitably different. Occurrence is inevitable. In order to cope with this step, the pressure restraining surfaces 9a and 10a, which are the contact surfaces with the laminate films 4a and 4b, of the upper and lower heat welding jigs 9 and 10 also have predetermined steps. .

  The lower heat welding jig 9 includes a ribbon-shaped heater 13 along the longitudinal direction as an impulse-type heater through a glass tape 12 having electrical insulation and heat resistance on the upper surface of a stainless steel jig main body 11. It is pasted. Further, a heat-resistant fluororesin tape 14 is attached to the surface of the heater 13 to prevent the laminate film 4b from sticking. And the part corresponding to the lead terminal 2 on the positive electrode side of the pressure restraining surface 9a of the lower heat welding jig 9 which becomes the contact surface with the laminate film 4b at the time of heat welding corresponds to the step described above. Therefore, a concave portion 9b is formed.

  More specifically, a portion of the jig main body 11 of the lower heat welding jig 9 on the back side of the heater 13 and corresponding to the lead terminal 2 on the positive electrode side has a notch having a shape such as a concave shape. 9c is formed, and a heat insulating material 15 is fitted into the notch 9c. And the recessed part 9b used as a part of pressurization restraint surface 9a of the lower heat welding jig | tool 9 is formed in the upper surface of this heat insulating material 15. As shown in FIG. The material of the heat insulating material 15 is a heat-resistant resin or rubber material. As the resin, fully aromatic polyester, aromatic polyamide, poimide, polyethersulfone, polyamideimide, polybenzimidazole, polyether ether ketone (PEEK) are used. In particular, in terms of shape followability with respect to the lead terminal 2 sandwiched between the laminate films 4a and 4b, it is desirable that the heat insulating material 15 is an elastic member having appropriate elasticity at the same time. Or the thing made from a fluororubber shall be used.

  Here, it can be understood that the upper thermal welding jig 10 is an inverted version of the lower thermal welding jig 9, and therefore the lower thermal welding jig 9 is the lower thermal welding jig 9. The same reference numerals are given to the parts common to and the detailed description thereof will be omitted.

  Also, the ribbon-shaped heater 13 as the impulse-type heater described above is heated by instantaneously applying a low voltage / high current to generate heat and heating / melting the laminate films 4a and 4b as objects. Therefore, after the energization is completed, the pressure is maintained for a predetermined time and the cooling is performed.

  Therefore, in the heat welding apparatus configured as described above, as shown in FIG. 4A, the upper and lower heat welding jigs 9 and 10 are separated from each other, and the laminate 5 shown in FIG. The two upper and lower laminate films 4a and 4b to be the surrounding laminate film outer package 4 are supported by a support member (not shown), and the parts to be thermally welded of these laminate films 4a and 4b are vertically heat welded jigs 9. , 10 to position.

  If the relative positioning between the upper and lower laminate films 4a and 4b and the upper and lower heat welding jigs 9 and 10 to be the laminate film outer package 4 is made, the lower heat welding jig 9 and the upper heat welding jig 9 Together with the jig 10, the upper and lower laminate films 4 a and 4 b are pressed and restrained from above and below as shown in FIG. And in this pressurization restraint state, it impulse-energizes to each heater 13 and heat-welds. The conventional so-called hot plate type heater requires about 13 seconds to complete the welding, whereas the impulse type heater 13 as described above completes the thermal welding in about 4 seconds.

  In this case, in the part corresponding to the lead terminal 2 in FIG. 4B, the upper and lower two laminated films 4a and 4b are different from the part where the upper and lower laminated films 4a and 4b are directly heat-sealed. Since the lead terminal 2 is sandwiched between them, and the heat capacity of the lead terminal 2 itself is relatively large, part of the heat applied for heat welding escapes to the lead terminal 2 side, The temperature for welding at the site will be relatively low. On the other hand, except for the special feature that the heat capacity of the lead terminal 2 is large as described above, if attention is paid to the heat holding performance at the relevant part, each of the heaters 13 of the upper and lower heat welding jigs 9, 10. Because the heat insulating material 15 is interposed on the back side and the portion corresponding to the lead terminal 2, for the heat insulating effect of the heat insulating material 15, in the heat welding portion in the portion corresponding to the lead terminal 2, The heat transfer from each heater 13 to the jig body 11 side of the upper and lower heat welding jigs 9 and 10 can be suppressed, and the welding temperature can be kept relatively high.

  Then, in a portion other than the portion corresponding to the lead terminal 2 in FIG. 4B, that is, in a portion where the two upper and lower laminate films 4 a and 4 b are directly heat welded, the heat insulating material 15 is provided on the back side of the heater 13. Since it does not exist, a part of the heat escapes from the heater 13 to the jig body 11 side of the upper and lower heat welding jigs 9 and 10, and the temperature for welding at the part becomes relatively low. become.

  This is because, in FIG. 4B, the amount of heat that escapes to the lead terminal 2 side at the portion corresponding to the lead terminal 2, and the two upper and lower laminate films 4a and 4b without the lead terminal 2 interposed therebetween. The amount of heat that escapes to the jig body 11 side of the upper and lower heat welding jigs 9 and 10 from the part where the heat welding is directly welded is almost offset or the lead terminal 2 in the part corresponding to the lead terminal 2. It means that the amount of heat that escapes to the side is smaller.

  Therefore, even if there is an amount of heat that escapes to the lead terminal 2 side in a portion corresponding to the lead terminal 2, the heat insulating material 15 makes it possible to maintain a high amount of heat at the portion, and as a result, the lead terminal The welding temperature can be made substantially uniform between the portion corresponding to 2 and the portion not. Thereby, generation | occurrence | production of the heat-welding defect in the part corresponding to the lead terminal 2 is suppressed, and the reliability of the sealing or sealing process of the laminate film exterior body 4 improves.

  In addition, since the heat insulating material 15 is an elastic member such as silicone rubber or fluorine rubber having appropriate elasticity, it corresponds to the heat insulating material 15 among the pressure restraining surfaces 9a, 10a of the upper and lower heat welding jigs 9, 10. The portion to be attached has good followability to the laminate films 4a and 4b between which the lead terminal 2 is sandwiched, and between the lead terminal 2 and the laminate films 4a and 4b or between the laminate films 4a and 4b and the upper and lower heat welding jigs 9, The generation of a gap between the ten pressure restraint surfaces 9a and 10a can be suppressed, and more uniform heat welding can be performed. Therefore, this also improves the reliability of sealing or sealing treatment of the laminate film outer package 4.

  The description so far has been made based on FIG. 4 in which the portion corresponding to the lead terminal 2 on the positive electrode side in FIG. 3 is enlarged, but corresponds to the lead terminal 3 on the negative electrode side in FIG. The structure and behavior of the part are basically the same as those in FIG.

On the other hand, the lead terminal 2 on the positive electrode side in FIG. 3 is made of aluminum, whereas the lead terminal 3 on the negative electrode side is made of copper. Then, copper (thermal conductivity: 386 W · m) used in the lead terminal 3 on the negative electrode side rather than aluminum (thermal conductivity: 237 W · m ⁻¹ K ⁻¹ ) used in the lead terminal 2 on the positive electrode side. ^-1 K ^-1 ) has a higher thermal conductivity.

  Therefore, considering the difference in material between the lead terminals 2 and 3, the copper lead terminal 3 on the negative electrode side is larger than the thermal conductivity of the heat insulating material 15 corresponding to the aluminum lead terminal 2 on the positive electrode side. It is assumed that the thermal conductivity of the heat insulating material 15 corresponding to the above is set low in advance. Specifically, is the thickness dimension H in the vertical direction of the heat insulating material 15 in the portion corresponding to the negative lead terminal 3 larger than that of the heat insulating material 15 in the portion corresponding to the positive lead terminal 2? Alternatively, the material of the heat insulating material 15 corresponding to the negative lead terminal 3 is made to have a lower thermal conductivity than that of the heat insulating material 15 corresponding to the positive lead terminal 2.

  Accordingly, when the portions corresponding to the positive-side lead terminal 2 and the portion corresponding to the negative-side lead terminal 3 are simultaneously heat-welded by the common upper and lower heat-welding jigs 9 and 10, Since the copper used for the lead terminal 3 on the negative electrode side has higher thermal conductivity, the portion corresponding to the lead terminal 3 on the negative electrode side tends to have a lower welding temperature. On the other hand, by increasing the thickness dimension of the heat insulating material 15 in the portion corresponding to the lead terminal 3 on the negative electrode side as described above or by making the thermal conductivity of the heat insulating material 15 low in advance, the negative electrode The heat transfer from the portion corresponding to the lead terminal 3 on the side to the main body 11 side of the upper and lower heat welding jigs 9 and 10 can be made slow, resulting in the lead terminal 3 on the negative electrode side. It is possible to increase the welding temperature at the portion to be applied.

  Here, the impulse-type heater 13 is used as an embodiment, but the present invention is not limited to this as long as it is a device that thermally welds the four sides of the laminate film outer package. Moreover, the heat insulating material 15 should just have a heat conductivity lower than the stainless steel jig | tool main body.

Claims (6)

A method for manufacturing a laminate type secondary battery in which a battery element including an electrode is housed in an exterior film, and a terminal portion of the electrode is led out of the exterior film, and a peripheral portion of the exterior film is sealed by thermal welding. In
In performing heat welding treatment by pressurizing and restraining the peripheral portion of the outer film with a heat welding jig equipped with a heater on the contact surface side with the outer film,
In the portion corresponding to the terminal portions of the electrodes, while interposing a heat insulating material between the jig body and the heater of the heat welding jig facilities heat welding process, other than the portion corresponding to the terminal portions of the electrodes in part, the production method of a laminate type secondary battery in which the thermal welding process facilities Suyo with no interposed insulation between the jig body and the heater of the thermal welding tool.   The method for manufacturing a laminated secondary battery according to claim 1, wherein the heat insulating material is an elastic member.   The electrode has a positive electrode and a negative electrode, and the heat insulating material corresponding to the terminal portion of the negative electrode has a lower thermal conductivity than the heat insulating material corresponding to the terminal portion of the positive electrode. Item 3. A method for producing a laminate type secondary battery according to Item 2. An apparatus for manufacturing a laminate type secondary battery in which a battery element including an electrode is housed in an exterior film, a terminal portion of the electrode is led out of the exterior film, and a peripheral portion of the exterior film is sealed by thermal welding. In
The outer peripheral film is subjected to thermal welding treatment by pressurizing and restraining the peripheral portion of the outer film with a heat welding jig provided with a heater on the contact surface side with the outer film,
In the portion corresponding to the terminal portions of the electrodes, Ri interposed Citea insulation between the jig body and the heater of the heat welding jig, in a portion other than the portion corresponding to the terminal portions of the electrodes, heat An apparatus for manufacturing a laminate type secondary battery in which a heat insulating material is not interposed between a jig body of a welding jig and a heater .   The apparatus for manufacturing a laminated secondary battery according to claim 4, wherein the heat insulating material is an elastic member.   6. The electrode has a positive electrode and a negative electrode, and the heat insulating material corresponding to the terminal portion of the negative electrode has a lower thermal conductivity than the heat insulating material corresponding to the terminal portion of the positive electrode. An apparatus for producing a laminated secondary battery according to 1.

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