KR100546878B1 - Preparation method and an apparatus of electrode tab attachment for secondary battery - Google Patents

Abstract

The present invention relates to a method and apparatus for manufacturing an electrode tab attachment for a secondary battery, wherein the manufacturing method of the present invention includes an attachment portion attached to a surface of an electrode tab and a wing portion extending a predetermined length to both sides of the electrode tab. A temporary welding step of welding the insulating sealing film to correspond to the upper and lower surfaces of the electrode tab, respectively; (S2) a first welding step of heating and pressing the entire surface of the insulating sealing film 20 to 50 ° C. higher than the melting point of the insulating sealing film so that the insulating sealing film completely surrounds and seals the electrode tab; And (S3) a second adjoining step of heating and pressing the entire surface of the insulating sealing film by 50 to 80 ° C. higher than the melting point of the insulating sealing film, respectively. The electrode tab attachment body manufactured according to the present invention can be usefully used in a large capacity secondary battery since the junction between the electrode tab and the insulating sealing film is completely sealed even when the electrode tab having a considerable thickness is used.

Description

Manufacturing method and apparatus of electrode tab attachment body for secondary battery {PREPARATION METHOD AND AN APPARATUS OF ELECTRODE TAB ATTACHMENT FOR SECONDARY BATTERY}

1 is a perspective view schematically showing the structure of a typical lithium secondary battery.

Figure 2a is a schematic cross-sectional view showing a unit cell structure of a typical lithium secondary battery.

Figure 2b is a schematic cross-sectional view showing a bicell structure of a typical lithium secondary battery.

Figure 3 is a perspective view schematically showing an electrode tab attachment.

4 is a cross-sectional view showing a state in which the sealing portion of the packaging material and the electrode tab are bonded by using the electrode tab attachment body having the insulating sealing film attached to both sides of the electrode tab.

5 is a process diagram schematically showing a process and apparatus for manufacturing an electrode tab attachment body according to the present invention;

Figure 6 is a perspective cross-sectional view of the cylindrical roller heating press that can be used during the primary temporary welding during the manufacturing process of the electrode tab attachment according to the present invention.

<Explanation of symbols for the main parts of the drawings>

10 Lithium secondary battery 14 Anode tab 15 Anode tab

17 Insulating sealing film 16 Anode grid 18 Anode grid

20 Battery unit 32 Storage unit 34 Sealing unit

40 Packing material 41 Electrode tab 50 Cathode tab attachment

52 ... Cylindrical Roller Heating Press

The present invention relates to a method for producing an electrode tab attachment body for a secondary battery.

In general, many studies have been conducted on secondary batteries used as power sources for electronic products, because the structure of portable electronic products such as video cameras, portable telephones, portable PCs, etc. has been reduced in weight or high in functionality. Such secondary batteries can be used continuously by charging / discharging.

A lithium secondary battery is classified into a lithium metal battery using a liquid electrolyte, a lithium ion battery, and a lithium polymer battery using a polymer solid electrolyte according to the type of electrolyte. Lithium polymer batteries are classified into fully solid lithium polymer batteries containing no organic electrolyte at all and lithium polymer batteries using a gel polymer electrolyte containing organic electrolyte according to the type of polymer solid electrolyte. Lithium secondary batteries are capable of high capacity and relatively easy to deform, and thus the use of batteries is expanding to power tools, medical equipment, leisure equipment, electric vehicles, etc. to be.

1 is a perspective view schematically showing the structure of a typical lithium secondary battery.

Referring to FIG. 1, the lithium secondary battery 10 includes a tab part including a battery part 20, a positive electrode tab 15, and a negative electrode tab 14, and a packing material 40 accommodating the battery part.

As shown in FIG. 2A, the battery unit 20 is a unit cell 28 arranged in the order of the positive electrode plate 22 / separator 24 / the negative electrode plate 26 or the unit cell 28 shown in FIG. 2B. As described above, the bi-cells (Bi-Cell) arranged in the order of the positive electrode plate 21 / the separator 23 / the negative electrode plate 25 / the separator 23 / the positive electrode plate 21 / the separator 23 / the negative electrode plate 25 ( It has a structure in which a plurality of 27) are laminated in accordance with battery capacity.

As shown in FIG. 1, the positive electrode plates 21 and 22 have the positive electrode grids 16 drawn out from one edge thereof, and the negative electrode plates 26 and 25 also have the negative electrode grids 18 drawn out from one edge thereof, respectively. . One end of the positive electrode grid 16 and the negative electrode grid 18 is connected to the electrode tabs (anode tab 15 and negative electrode tab 14) by welding or the like, respectively, and the positive electrode tab 15 and the negative electrode tab ( 14) has a predetermined length so as to enable energization with the outside. Referring to FIG. 3, the insulating sealing film 17 is bonded to both sides of the electrode tab 41 and wrapped to completely seal the electrode tab 41. The wing portions of the insulating sealing film 17 extending a predetermined length to both sides of the electrode tab 41 are thermally bonded to each other. In the conventional secondary battery manufacturing process, the electrode tab 41 is separately manufactured in the form of a so-called “electrode tab attachment body 50” in which the electrode tab 41 is completely sealed by the insulating sealing film 17. , Is welded to the grid.

Returning to FIG. 1 again, the packing material 40 includes an accommodating part 32 in which the battery part 20 is accommodated, and a sealing part 34 for vacuum sealing after injecting electrolyte solution to maintain the airtightness of the accommodating part 32. . The contact portion where the positive electrode tab 15 and the negative electrode tab 14 meet the sealing portion 34 is interposed with an insulating sealing film 17 that encloses and seals the electrode tab. When the sealing portion 34 is heated and pressurized, the insulating portion is insulated. The sealing film 17 is heat-sealed to completely seal the contact portions of the electrode tabs 14 and 15 and the sealing portion 34 (see FIG. 4). Accordingly, the electrolyte (not shown) is prevented from leaking to the outside from the accommodating part 32, and external moisture is prevented from flowing into the inside, and a short circuit that may occur at the electrode tab part is prevented. Therefore, the sealing of the accommodating part 32 is very important.

In FIG. 3, the conventional electrode tab attachment body 40 is fixed (adhered) by applying a predetermined heat to correspond to each other on the upper and lower surfaces of the electrode tab 41, and is then welded to both surfaces of the electrode tab 41. The front surface of the insulating sealing film 17 is manufactured through a single welding process of thermally fusion bonding with heating and pressing means located above and below the electrode tab 41. Since the thickness of the electrode tab generally used is 100 μm or less, the insulating sealing film was able to completely seal the electrode tab to some extent by such a conventional method.

However, in order to manufacture a large capacity secondary battery, the thickness of the electrode tab needs to be increased. When the thickness of the electrode tab is increased, the sealing property is poor because a complete bonding is not performed at the insulating sealing film portion surrounding the end portion of the electrode tab. In other words, the insulating sealing film subjected to heat and pressure by the heating and pressing means in the welding process is initially wrapped around the electrode tab and heat-bonded, but as time passes, the insulating sealing film shrinks and adheres to the end portion of the electrode tab. The part will fall off. This is believed to be due to the large shrinkage stress inside the insulating sealing film generated during the heating and pressing process of the welding process in a few seconds. This poor sealing becomes larger as the thickness of the electrode tab increases, and causes many problems in manufacturing a large capacity secondary battery.

 The present invention has been made to solve the above problems, the electrode tab and the sealing portion of the insulating sealing film is completely sealed even when using a large thickness of the electrode tab, electrode tab that can be usefully used in a large capacity secondary battery The object is to provide a method for producing the attachment.

Another object of the present invention is to provide an apparatus for manufacturing an electrode tab attachment body for a secondary battery, in which a bonding portion of an electrode tab and an insulating sealing film is completely sealed and no bubbles remain.

In order to achieve the above object, the manufacturing method of the electrode tab attachment body for a secondary battery of the present invention (S1) an insulating sealing film having an attachment portion attached to the surface of the electrode tab and a wing portion extending a predetermined length to both sides of the electrode tab. A temporary step of welding to correspond to each of the upper and lower surfaces of the electrode tab; (S2) a first welding step of heating and pressing the entire surface of the insulating sealing film 20 to 50 ° C. higher than the melting point of the insulating sealing film so that the insulating sealing film completely surrounds and seals the electrode tab; And (S3) a second adjoining step of heating and pressing the entire surface of the insulating sealing film by 50 to 80 ° C. higher than the melting point of the insulating sealing film, respectively.

In addition, in order to achieve the above another object, the manufacturing apparatus of the electrode tab attachment body for a secondary battery of the present invention is a temporary heating press, the insulating sealing film to weld the electrode tab to both sides of the electrode tab so as to correspond to each other. A device comprising a primary and a secondary contact heating press sequentially for heating and pressing the front surface of the insulating sealing film welded to both sides of the electrode tab to completely enclose the sealing, the primary contact heating press is on both sides of the electrode tab The outer surface of the weldable insulating sealing film has a width that can be heated and pressurized, and the outer layer is made of elastic material so that the heated and pressurized portion of the supplied welded insulating sealing film can be moved from one side to the other side. It consists of a cylindrical roller heating press.

Hereinafter, a method of manufacturing an electrode tab attachment member for a secondary battery according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

According to the manufacturing method of the electrode tab attachment body of the present invention, first, the insulating sealing film is welded to the upper and lower surfaces of the electrode tab so as to correspond to each other (S1). The insulating sealing film fixed by the temporary welding step has an attachment portion attached to the surface of the electrode tab and a wing portion extending a predetermined length to both sides of the electrode tab. The insulating sealing film may be used as long as it is a sealing film generally used for attaching electrode tabs as a film having thermoplasticity and insulation, and is a known insulating sealing film known to be used by being attached to a conventional electrode tab. Modified polypropylenes such as modified polypropylene and modified polyethylene can be used. The welding step is a step of fixing the insulating sealing film to the electrode tab so as to smoothly perform the welding step to be described later, a method of thermally sealing the insulating sealing film on the upper and lower surfaces of the electrode tab attachment through a conventional heating and pressing means. have. It is sufficient that only the attachment portion of the insulating sealing film is fixed by heat fusion to the electrode tab by the temporary welding step, and the wing portions of the insulating sealing film corresponding to each other need not be adhered to each other but are not excluded.

Subsequently, the entire surface (including the attaching portion and the wing portion) of the welded insulating sealing film is heated and pressurized 20 to 50 ° C. higher than the melting point of the insulating sealing film, respectively (S2: first adjoining step).

The attachment portion of the insulating sealing film is completely heat-sealed with the electrode tabs by the first adhering step, and the upper and lower insulating sealing film wings extending to both sides of the electrode tabs are also heat-sealed with each other to completely surround the electrode tabs. The first contacting step is sufficient for a short time of several seconds, and if the heating is pressed for too long, the insulating sealing film may be thermally decomposed. The insulating sealing film welded to both sides of the electrode tab in the first adjoining step is preferably heated and pressed at the same time, but may be separately heated and pressed.

Thereafter, the front surface of the first insulated insulating sealing film is heated and pressurized by 50 to 80 ° C. higher than the melting point of the insulating sealing film, respectively (S2: second adjoining step).

As described above, the primary insulated insulating sealing film is completely wrapped around the electrode tab and heat-sealed. However, since the first contacting step is performed by high temperature treatment within a short time of several seconds, the shrinkage stress remains large in the heat-sealed insulating sealing film. Therefore, as the time passes, the insulating sealing film shrinks and, in particular, the portion adhered to the end portion of the electrode tab is dropped, so that the sealing property is poor. Therefore, by reducing the shrinkage stress present in the insulating sealing film through the secondary adhering to prevent the sealing performance is poor. Secondary close is also sufficient as a short time of a few seconds. The insulating sealing film primaryly intimately contacted on both sides of the electrode tab in the second adjoining step is preferably heated and pressurized at the same time.

Through the above two times of adhering processes, the shrinkage stress existing in the insulating sealing film is greatly reduced, so that the sealing property of the electrode tab is maintained over time. Of course, the above-described adjacency process can be roughed several times as necessary.

5 is a schematic process diagram illustrating a method of manufacturing an electrode tab attachment body for a secondary battery according to the present invention. Referring to FIG. 5, electrode tabs 41 in a strip form are continuously supplied. If necessary, the electrode tab 41 may be subjected to ultrasonic cleaning or surface treatment, and may be preheated before being introduced into the temporary welding step. Subsequently, an insulating sealing film is introduced to both surfaces of the electrode tab 41 at predetermined intervals, and is welded by the heating press 51.

 Then, the electrode tab 41 to which the insulating sealing film 17 is welded is supplied to the heating press 52 for primary contact, thereby primary contact. The heating press 52 for the primary contact may use a conventional heating press having a flat surface in contact with the insulating sealing film 17, but air bubbles between the electrode tab 41 and the insulating sealing film 17 do not remain. It is preferable to use a heating roller 52 having a cylindrical roller shape. When heating and pressurizing using the cylindrical roller-shaped heating press 52, the portion in which the insulating sealing film 17 is heated and pressurized starts from one side and moves to the other side, so that the electrode tab 41 and the insulating sealing film 17 Air is removed between the air bubbles and bubbles are not generated. Since the electrode tab used in the high capacity secondary battery has to have a large width as well as a thickness, it is difficult to remove bubbles by using a conventional flat heating press alone. However, the cylindrical roller heating press according to the present invention can solve such a problem. The cylindrical roller heating press has a width capable of heating and pressing the entire surface of the insulating sealing film welded to both sides of the electrode tab. 6 is a perspective cross-sectional view of the cylindrical roller heating press 52 used for primary abutment. As shown in FIG. 6, the outer layer 52a of the cylindrical roller heating press 52 is preferably made of an elastic material such as silicon rubber. The outer layer 52a made of an elastic material may improve the sealing property by bringing the insulating sealing film closer to the end surface of the electrode tab when the insulating sealing film is first brought into close contact with the electrode tab. If necessary, the surface of the outer layer 52a made of an elastic material may be formed by coating or laminating a blocking material that prevents the insulating sealing film from being attached to the outer layer 52a.

Subsequently, the electrode tab on which the primary sealing of the insulating sealing film is completed is supplied to the heating press 53 for the secondary welding, and the second sealing is performed. As the heating press 53 for the secondary contact, it is preferable to use a conventional heating press that is flat so that the heat sealing of the insulating sealing film 17 and the electrode tab is sufficient, but the above-described cylindrical roller 52 may be used. Of course, the lower surface of the heating press 53 in contact with the insulating sealing film is preferably made of a flexible material as described in the cylindrical roller (52).

The electrode tab attachment body, which has been manufactured according to the above-described process, is cut into a predetermined length and supplied to the electrode tab attachment body for a secondary battery.

 Hereinafter, the present invention will be described in detail with reference to Examples. However, embodiments according to the present invention can be modified in many different forms, the scope of the present invention should not be construed as limited to the embodiments described below. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

Example 1

As the electrode tab, a long nickel strip having a thickness of 0.2 mm and a width of 7 mm is used, and as an insulating sealing film, an insulating sealing film made of a modified polypropylene material (thickness 0.1 mm, width 6.0 mm, melting point 145 degrees) is used. The electrode plate attachment body was manufactured according to the process shown in FIG.

The processing temperature, press pressure and time of the welding step for the insulating sealing film were 160 degrees, 0.2 MPa and 2.4 seconds, respectively, and the processing temperature, press pressure and time of the first welding step were 180 degrees, 0.4 MPa and 3.0 seconds, respectively. The treatment temperature, press pressure and time of the secondary adjoining step are 210 degrees, 0.4 MPa and 3.0 seconds, respectively. The heating press of the first adjoining step was the same as the heating press of the conventional second adjoining step.

Example 2

The electrode tab attachment material and the conditions of the welding step in manufacturing were the same as in Example 1, and the processing temperature, the press pressure and the time of the first welding step were 170 degrees, 0.4 MPa and 2.0 seconds, respectively. The temperature, press pressure and time were 190 degrees, 0.4 MPa and 2.0 seconds, respectively, and the treatment temperature, press pressure and time of the third contact stage were 210 degrees, 0.4 MPa and 2.0 seconds, respectively. The heating press of the first abutment stage used a cylindrical roller heating press shown in FIG.

Comparative Example 1

As the electrode tab, it is used as a general purpose in a small battery and uses a long nickel strip having a thickness of 0.1 mm and a width of 7 mm, which is relatively easy to manufacture due to its thin thickness, and as the insulating sealing film, the same modified polypropylene material as used in the examples. The electrode plate attachment body was manufactured according to the process shown in Fig. 5 using the insulating sealing film [(thickness 0.1mm, width 6.0mm, melting point 145 degree]] of the insulating sealing film. And the time was 160 degrees, 0.2 MPa and 2.4 seconds, respectively, and the treatment temperature, press pressure and time of the welding stage were 190 degrees, 0.4 MPa and 3.0 seconds, respectively, and only the primary welding was performed. Conventional heating press was used.

Comparative Example 2

As the electrode tab, a long nickel strip having a thickness of 0.2 mm and a width of 7 mm is used, and as an insulating sealing film, an insulating sealing film made of a modified polypropylene material (thickness 0.1 mm, width 6.0 mm, melting point 145 degrees) is used. An electrode plate attachment body was prepared according to the process shown in Fig. 5. The treatment temperature, the press pressure and the time of the temporary welding step for the insulating sealing film were 160 degrees, 0.2 MPa and 2.4 seconds, respectively, and the treatment temperature and the press of the welding step. The pressure and time were 210 degree, 0.4 MPa, and 6.0 second, respectively, and only primary welding was performed.The heating press of the welding process used the conventional heating press.

[Electrolyte Dipping Test]

The electrode tab attachment body is used as a battery part, so that the adhesion between the metal material and the sealing film is maintained even in the electrolyte environment inside the battery. After dipping the sieve and measuring the change in adhesion time, the results are shown in Table 1, and the evaluation criteria are as follows.

+++: Maintain 80 ~ 100% of adhesion surface of electrode tab and sealing film (0 ~ 20% electrolyte penetration of adhesion surface)

++: 50 ~ 80% adhesion between electrode tab and sealing film (20 ~ 50% electrolyte penetration)

+: 20 ~ 50% of the adhesive surface of electrode tab and sealing film (50 ~ 80% electrolyte penetration)

-: 0 ~ 20% adhesion between electrode tab and sealing film (80 ~ 100% electrolyte penetration)

The test conditions were filled with 10ml vials filled with electrolyte (Japan Baeheungsan; 1.0M LiPF6 + EC: DEC: DMC (1: 1: 1)) in a glove box filled with nitrogen, and the prepared electrode tab attachment was added. Was sealed with a rubber stopper and an aluminum cap, and stored in an oven maintaining a temperature of 60 ° C to measure the change in adhesion over time.

[Vacuum Storage Test of Model Battery]

In the battery structure shown in FIG. 1, the battery unit 20 is removed, and instead, the battery part 20 is replaced with a sponge of the same standard in which 2 ml of electrolyte is contained, and then a pair of electrode tab attachment bodies are drawn out of the battery at the top of the battery. The weight loss of the model battery over time was measured in a vacuum oven of 80 degrees and -70mmHg conditions, and the results are shown in Table 2 below. In this method, since the inside of the model cell is relatively positive pressure and the vacuum oven condition is negative pressure, the negative electrode tap in a faster time by measuring the weight (mg) of the model battery which is reduced by the force of the discharge of the electrolyte inside the cell to the outside. This was done to confirm the sealability of the attachment.

Elapsed time Example 1 Example 2 Comparative Example 1 Comparative Example 2 24 hours +++ +++ +++ + 48 hours +++ +++ +++ - 72 hours ++ +++ +++ -

Elapsed time Example 1 Example 2 Comparative Example 1 Comparative Example 2 24 hours -7 -5 -6 -28 48 hours -8 -8 -7 * 72 hours -11 -8 -6 * 96 hours -18 -11 -9 *

Referring to the results of Table 1 and Table 2, according to the present invention, when manufacturing the electrode tab attachment body in a multi-stage heat fusion welding condition to gradually increase the temperature conditions, the adhesion and sealing of the electrode tab and the sealing film is improved In particular, when a thick plate electrode tab having a thickness of 0.2 mm or more is manufactured by this manufacturing method, adhesiveness and sealability comparable to that of a thin plate electrode tab attachment body having a thickness of 0.1 mm are generally maintained. The lithium secondary battery can be designed.

As described above, the electrode tab attachment body manufactured according to the present invention can be usefully used in a large capacity secondary battery because the junction portion of the electrode tab and the insulating sealing film is completely sealed even when the electrode tab having a considerable thickness is used. have. In addition, in the apparatus for manufacturing an electrode tab attachment body, when a cylindrical roller-shaped heating press is used during primary welding, air between the electrode tab and the insulating sealing film is removed, and bubbles are not left. When the outer layer is made of a flexible material, the sealing property can be improved by bringing the insulating sealing film closer to the end face of the electrode tab.

Claims (7)

(S1) a temporary welding step of welding the insulating sealing film having the attachment portion attached to the surface of the electrode tab and the wing portion extending a predetermined length to both sides of the electrode tab so as to correspond to the upper and lower surfaces of the electrode tab, respectively; (S2) a first welding step of heating and pressing the entire surface of the insulating sealing film 20 to 50 ° C. higher than the melting point of the insulating sealing film so that the insulating sealing film completely surrounds and seals the electrode tab; And (S3) a second welding step of post-treatment by heating and pressing the entire surface of the insulating sealing film 50 ~ 80 ℃ higher than the melting point of the insulating sealing film, respectively; manufacturing method of the electrode tab attachment body for a secondary battery comprising a . The method of claim 1, The insulating sealing film is a manufacturing method of the electrode tab attachment body for a secondary battery, characterized in that made of a polyolefin resin. The method of claim 1, The heating pressurization of the step (S2) is a manufacturing method of the electrode tab attachment body for a secondary battery, characterized in that consisting of a cylindrical roller heating press. The method of claim 3, The outer layer of the cylindrical roller heating place is a manufacturing method of the electrode tab attachment body for a secondary battery, characterized in that made of an elastic material. The method of claim 4, wherein A method for manufacturing an electrode tab attachment body for a secondary battery, characterized in that an inner blocking layer is further formed on the surface of the outer layer of the cylindrical roller heating place. Temporary heating press for welding the insulating sealing film on both sides of the electrode tab so as to correspond to each other, and primary and second heating and pressing the front surface of the insulating sealing film welded to both sides of the electrode tab so that the insulating sealing film completely surrounds and seals the electrode tab. An apparatus having a car induction heating press sequentially The primary contact heating press has a width capable of heating and pressing the entire surface of the insulating sealing film welded to both sides of the electrode tab, and the heating and pressing portion of the supplied welded insulating sealing film starts from one side and the other. Apparatus for producing an electrode tab attachment body for a secondary battery, characterized in that the outer layer is a cylindrical roller heating press made of a material having an elastic force to be moved to the side. 7. The apparatus for manufacturing an electrode tab attachment body for a secondary battery according to claim 6, wherein an anti-blocking layer is further formed on the surface of the outer layer of the cylindrical roller heating place.

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