Electrode assembly interleaving roller

Abstract

The present invention relates to an electrode assembly lamination roller for laminating an electrode and a separator, The interleaving roller includes a center portion and end portions located on both ends of the center portion based on a longitudinal direction. The surface temperature of the end portion is higher than that of the central portion.

Description

[Technical field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0143770 filed on October 26, 2021 and Korean Patent Application No. 10-2022-0137063 filed on October 24, 2022, and all contents disclosed in the documents of the relevant Korean patent applications are incorporated as part of this specification.

[0002] The present invention relates to an electrode assembly lamination roller for laminating an electrode and a separator. [Background technology]

[0003] 2. Description of the Related Art With the increasing technological development and demand for mobile devices, the demand for secondary batteries as an energy source is rapidly increasing. As a result, much research is being conducted on secondary batteries that can meet various demands.

[0004] Typically, in terms of battery shape, there is a high demand for prismatic secondary batteries and pouch-type secondary batteries that are thin and can be applied to products such as mobile phones, and in terms of materials, there is a high demand for lithium secondary batteries such as lithium ion batteries and lithium ion polymer batteries, which have advantages such as high energy density, discharge voltage, and output stability.

[0005] Secondary batteries are also classified according to the structure of the electrode assembly having a positive electrode / separator / negative electrode structure. Representative examples include a jelly-roll (wound-type) electrode assembly in which long sheet-type positive and negative electrodes are wound with a separator interposed therebetween, a stack-type electrode assembly in which a number of positive and negative electrodes cut into a predetermined size are stacked in sequence with a separator interposed therebetween, and a stack / folding type electrode assembly in which a bi-cell or full cell in which a predetermined unit of positive and negative electrodes are stacked with a separator interposed therebetween is wound up with a separator sheet.

[0006] The electrode assembly consisting of a positive electrode / separator / negative electrode may have a simple laminated structure, or may have a structure in which a number of electrodes (positive and negative electrodes) are laminated with a separator interposed therebetween and then laminated by heating / pressure. In this case, lamination of the electrodes and separator is achieved by heating and pressing an adhesive layer applied on the separator and the electrodes facing each other. Therefore, the separator is generally coated with a binder material to improve adhesion to the electrodes.

[0007] In the lamination process of the electrode and the separator, the electrode, which is taken out from the electrode roll and cut, is generally placed on the separator sheet, and the separator sheet and the electrode are pressurized and heated by the lamination roller to bond the electrode and the separator sheet. The separator sheet is cut with the electrode bonded thereto to complete the electrode assembly.

[0008] However, since the widthwise ends of the electrode assembly are thinner than the center, pressure and heat are not applied sufficiently compared to the center, which may result in a decrease in adhesive strength at the widthwise ends.

[0009] Therefore, there is a strong need to solve these problems. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Korean Patent Publication No. 10-1361675 [Patent Document 2] Korean Patent Publication No. 10-2018-0023185 Summary of the Invention [Problem to be solved by the invention]

[0011] As a result of extensive research into solving the above problem, the inventors have found that by making the surface temperature of the ends located at both ends of the center of the interleaf roller higher than the surface temperature of the center of the interleaf roller, the adhesive strength at both ends in the full width direction of the electrode assembly can be improved, and have completed the present invention.

[0012] SUMMARY OF THE PRESENTLY PREFERRED EMBODIMENTS OF THE PRESENT EMBODIMENT An object of the present invention is to provide an electrode assembly lamination roller capable of improving adhesive strength at both ends of an electrode assembly in the width direction. [Means for solving the problem]

[0013] In order to achieve the above objective, The present invention provides an electrode assembly lamination roller for laminating an electrode and a separator, The interleaving roller includes a center portion and end portions located on both ends of the center portion based on a longitudinal direction. The interleaving roller includes a heating member therein, The surface temperature of the end portion is higher than that of the central portion.

[0014] In an embodiment of the present invention, the length of the interleaving roller may correspond to the overall length of the electrode assembly excluding the tap.

[0015] In one embodiment of the present invention, the surface temperature of the end portion may be 10 to 30° C. higher than the surface temperature of the center portion.

[0016] In one embodiment of the present invention, the surface temperature of the end portion may be developed to be 60 to 80°C, and the surface temperature of the center portion may be developed to be 40 to 60°C.

[0017] In one embodiment of the invention, the materials of the center and end portions may be different.

[0018] In one embodiment of the invention, the material of the end portions may have a higher thermal conductivity than the material of the central portion.

[0019] In an embodiment of the present invention, the heating member may apply heat of the same temperature to the central portion and the distal portion, or may cause the surface temperature of the distal portion to be higher than the surface temperature of the central portion.

[0020] In one embodiment of the invention, the material of the central and distal portions may be the same.

[0021] In one embodiment of the present invention, the heating member may be configured to generate a surface temperature at the end portion that is higher than a surface temperature at the center portion.

[0022] In one embodiment of the present invention, the ratio of the length of the central portion to the length of each end portion may be 2:1 to 5:1.

[0023] In an embodiment of the present invention, the interleaving roller may pressurize and heat the separator and the electrodes fed in the width direction of the electrode assembly.

[0024] In one embodiment of the present invention, the electrode assembly may be a bicell.

[0025] In an embodiment of the present invention, the interleaving roller may be a pair including an upper interleaving roller and a lower interleaving roller.

[0026] In an embodiment of the present invention, the interleaving rollers may include one or more pairs of interleaving rollers. Effect of the Invention

[0027] The electrode assembly lamination roller of the present invention has a higher surface temperature at the ends located at both ends of the center than at the center, thereby improving the problem of adhesive strength reduction that occurs at both ends in the entire width direction of the electrode assembly. [Brief description of the drawings]

[0028] [Figure 1]5A to 5C are perspective views each showing a manufacturing process of the electrode assembly. [Diagram 2] FIG. 2 is a perspective view of an electrode assembly interleaving roller according to an embodiment of the present invention; [Diagram 3] 1 is a photograph of an electrode assembly. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings, in order to enable those skilled in the art to easily carry out the present invention. However, the present invention may be embodied in several different forms and is not limited to the embodiments set forth herein.

[0030] In order to clearly describe the present invention, parts that are not relevant to the description will be omitted, and the same reference numerals will be used throughout the specification to refer to the same or similar components.

[0031] Furthermore, the terms and words used in this specification and claims should not be interpreted in a limited manner based on their ordinary or dictionary meaning, but should be interpreted in a meaning and concept that corresponds to the technical idea of ​​the present invention, based on the principle that an inventor can appropriately define the concept of a term in order to explain his / her invention in the best possible manner.

[0032] FIG. 1 is a perspective view that illustrates a typical manufacturing process for an electrode assembly.

[0033] Figure 1 shows the manufacturing process for a monocell consisting of one electrode and one separator.

[0034] Referring to FIG. 1, an electrode 121 taken out from an electrode roll 120 and cut is placed on a separator sheet 111 taken out from a separator roll 110, and the electrode 121 placed on the separator sheet 111 moves to a heating and pressurizing section 130 and passes through a lamination roller 140 which heats and pressurizes the separator sheet 111 and the electrode 121 to laminate them, thereby laminating the electrode 121 and the separator sheet 111.

[0035] Thereafter, the separator sheet 111 is cut with the electrode 121 attached thereto, and the electrode assembly 151 is completed.

[0036] Although FIG. 1 shows a process in which electrodes 121 are laminated on a separator sheet 111, it is of course possible to place electrodes on separators cut into unit separators and then laminate them.

[0037] FIG. 2 is a perspective view of an electrode assembly lamination roller 200 according to an embodiment of the present invention.

[0038] Referring to FIG. 2, an electrode assembly lamination roller 200 according to an embodiment of the present invention laminates an electrode and a separator, and may include a center portion 210 and end portions 220 located at both ends of the center portion 210 in a longitudinal direction, and the surface temperature of the end portions 220 may be higher than the surface temperature of the center portion 210.

[0039] In addition, the interleaving roller 200 may include a heating member (not shown) therein.

[0040] As described above, in the process of manufacturing the electrode assembly, the electrodes are disposed on the separator, and the separator has a greater length in the width direction than the electrodes. As a result, the two ends of the electrode assembly are not sufficiently heated and pressed by the lamination roller compared to the center, and the lamination is not properly performed at both ends of the electrode assembly, resulting in a decrease in adhesive strength. In addition, when manufacturing a bi-cell type electrode assembly, the thickness of both ends of the electrode assembly in the width direction is thinner than the thickness of the center, which can cause the above problem.

[0041] FIG. 3 is a photograph of the electrode assembly, where F is both ends of the electrode assembly in the overall width direction.

[0042] Conventional lamination rollers could not solve the above problem because the same temperature was applied to the center of the lamination roller and the ends located on both ends of the center, and the materials of the center and the ends were also the same.

[0043] Therefore, the electrode assembly lamination roller 200 according to one embodiment of the present invention aims to solve the problem of adhesive strength reduction at both ends of the electrode assembly in the entire width direction by making the surface temperature of the end portion 220 higher than the surface temperature of the center portion 210 and applying a higher temperature to both ends of the electrode assembly in the entire width direction than the center portion.

[0044] Therefore, the surface temperature of the end portion 220 may be 10 to 30° C. higher than the surface temperature of the center portion 210. In this temperature range, the adhesive strength of both ends in the width direction of the electrode assembly may be improved.

[0045] If the surface temperature of the end portion 220 is less than 10° C. higher than the surface temperature of the center portion 210, the effect of improving the adhesive strength at both ends in the width direction of the electrode assembly is negligible. If the surface temperature of the end portion 220 is more than 30° C. higher than the surface temperature of the center portion 210, the binder material in the separator may melt, preventing pores in the separator.

[0046] The surface temperature of the end portion 220 may be expressed at 60 to 80°C, and the surface temperature of the center portion 210 may be expressed at 40 to 60°C.

[0047] The central portion 210 and the distal portion 220 may be made of different materials, and the distal portion 220 may have a higher thermal conductivity than the central portion 210. Specifically, the distal portion 220 may have a higher thermal conductivity than the central portion 210 by 3 to 20 W / mK.

[0048] For example, the material of the end portion 220 may be a carbon steel material for mechanical construction or a steel material for carburizing, such as S45C or S50C, and the material of the center portion 210 may be a carbon steel material for mechanical construction, such as S45C or S15CK.

[0049] The thermal conductivity of the S45C is 49.8 W / mK, the thermal conductivity of the S50C is 52 W / mK, and the thermal conductivity of the S15CK is 32 W / mK.

[0050] If the material of the distal portion 220 has a higher thermal conductivity than the material of the central portion 210, the heating member may apply the same temperature to the central portion 210 and the distal portion 220, or may make the surface temperature of the distal portion 220 higher than the surface temperature of the central portion 210.

[0051] When the heating member applies the same temperature to the center 210 and the end portion 220, the surface temperature of the end portion 220 may be higher than the surface temperature of the center 210 because the material of the end portion 220 has a higher thermal conductivity than the material of the center 210. In this case, the electrode assembly lamination roller 200 may include one heating member. As a result, the heat distribution is linearly distributed on the electrode assembly lamination roller 200, and a sudden difference in surface temperature does not occur depending on the position of the electrode assembly, thereby preventing damage to the electrode assembly.

[0052] Additionally, the material of the distal portion 220 and the material of the central portion 210 may be the same.

[0053] If the material of the distal portion 220 and the material of the central portion 210 are the same, the heating member may be capable of making the surface temperature of the distal portion 220 higher than the surface temperature of the central portion 210 .

[0054] When the heating member makes the surface temperature of the distal portion 220 higher than the surface temperature of the central portion 210, heating members having different heat values ​​are used inside the distal portion 220 and the central portion 210. That is, the heating member included inside the distal portion 220 may have a higher heat value than the heating member included inside the central portion 210.

[0055] In this case, a plurality of heating elements with different heat values ​​may be used, or a single heating element may be used that provides different heat values ​​depending on the positions of the end portion 220 and the center portion 210. However, in this case, there may be insufficient space to insert the plurality of heating elements into the electrode assembly lamination roller 200. In order to insert the plurality of heating elements, sufficient space must be secured inside the end portion 220 and the center portion 210, and therefore the empty space inside the end portion 220 and the center portion 210 must be expanded. As the empty space increases, the weight of the lamination roller 200 decreases, and the pressure applied to the electrodes and the separator decreases, so that the electrodes and the separator may not be laminated. In addition, there is a problem that the manufacturing is complicated, and the electrode assembly may be damaged due to the sudden temperature difference applied to the center and both ends of the electrode assembly.

[0056] Therefore, it is most preferable that the material of the end portion 220 of the electrode assembly lamination roller 200 is different from the material of the center portion 210, the material of the end portion 220 has a higher thermal conductivity than the material of the center portion 210, and the heating member applies heat of the same temperature to the center portion 210 and the end portion 220.

[0057] The heating element may be, but is not limited to, a cartridge insert type heater, a sheath heater, or an induction heater.

[0058] The sheath heater has a coil wound around an inner core and heats the outer cylinder with radiant heat. For example, when the sheath heater is used as a heating member, the number of times the coil is wound in the central portion 210 and distal portion 220 regions can be made different to adjust the temperatures expressed on the surfaces of the central portion 210 and distal portion 220.

[0059] The electrode assembly may be a single cell consisting of one electrode and one separator, a mono-cell in which a separator is interposed between a positive electrode and a negative electrode, or a bi-cell in which two separators are interposed between three adjacent electrodes of different polarity. The mono-cell and bi-cell may include a form in which a separator is further added to the other side of the electrode that does not face the separator interposed between the electrodes.

[0060] Specifically, the bicell is a cell in which the same electrode is located at the outermost electrode, such as a unit cell of positive electrode / separator / negative electrode / separator / positive electrode and a unit cell of negative electrode / separator / positive electrode / separator / negative electrode. A unit cell with a positive electrode / separator / negative electrode / separator / positive electrode structure is defined as an "A-type bicell," and a unit cell with a negative electrode / separator / positive electrode / separator / negative electrode structure is defined as a "C-type bicell." In other words, a cell in which the electrode located at the center of the bicell is the negative electrode is called an A-type bicell, and a cell with the positive electrode is called a C-type bicell.

[0061] The electrode assembly is not particularly limited in type, but may be preferably a bicell.

[0062] Also, the electrode assembly may include a tap, and more specifically, the positive electrode may include a positive electrode tap, and the negative electrode may include a negative electrode tap.

[0063] The length of the interleaving roller 200 may correspond to the overall length of the electrode assembly excluding the tap.

[0064] Specifically, the length of the lamination roller 200 may be the same as the overall length of the electrode assembly excluding the tab, or may be 1 to 1.1 times, and preferably 1:1.05 times, the overall length of the electrode assembly excluding the tab.

[0065] The ratio of the length of the central portion 210 to the length of the end portion 220 may be 2:1 to 5:1.

[0066] In the electrode assembly, the thickness at both ends in the width direction is thinner than the thickness at the center, which causes a problem of reduced adhesive strength at both ends in the width direction. To solve this problem, the electrode assembly lamination roller 200 according to one embodiment of the present invention may pressurize and heat the separator and electrodes fed in the width direction of the electrode assembly.

[0067] Since the separator and the electrodes are fed in the width direction, the end of the lamination roller 200 comes into contact with both ends of the separator and the electrodes in the width direction, and by applying heat and pressure to the contact, the adhesive strength reduction problem occurring at both ends in the width direction can be improved.

[0068] In a conventional electrode assembly lamination roller, the adhesive strength at both ends in the full width direction is 70 to 80% of the adhesive strength at the center of the electrode assembly. However, in the electrode assembly lamination roller 200 according to an embodiment of the present invention, the adhesive strength at both ends in the full width direction may be 85 to 95% of the adhesive strength at the center of the electrode assembly. In other words, the electrode assembly lamination roller 200 according to an embodiment of the present invention can improve the adhesive strength at both ends in the full width direction of the electrode assembly.

[0069] Also, the lamination roller 200 may be a pair including an upper lamination roller and a lower lamination roller, or the number of the lamination rollers may be more than one.

[0070] For example, the lamination rollers 200 may be configured in two or more pairs, and n lamination rollers 200 may be arranged from a first lamination roller through which the electrodes and the separator pass first to an nth lamination roller arranged in sequence.

[0071] In addition, the interleaving roller 200 may be configured to set the time for pressing and heating the electrodes and the separator, and to adjust the rotation speed.

[0072] A person having ordinary skill in the art to which the present embodiment relates can understand that the present invention can be embodied in modified forms without departing from the essential characteristics. Therefore, the disclosed method should be considered in an explanatory and not a limiting sense. The scope of the present invention is defined in the claims, not the above description, and all differences within the scope equivalent thereto should be interpreted as being included in the present invention. EXAMPLES

[0073] Hereinafter, preferred examples will be presented to aid in understanding the present invention. However, the following examples are merely illustrative of the present invention, and it will be obvious to those skilled in the art that various changes and modifications are possible within the scope of the scope and technical ideas of the present invention. It is natural that such changes and modifications fall within the scope of the appended claims.

[0074] <Manufacturing of electrode assembly interleaving roller> Example 1. A slip roller was manufactured that included a center portion and end portions located on both ends of the center portion based on the longitudinal direction of the slip roller.

[0075] The central portion was made of S15CK, the end portion was made of S45C, and a cartridge insertion type heater was used as the heating element.

[0076] At this time, the length ratio of the center and each end was 3:1, the surface temperature expressed at the center was 60°C, and the surface temperature expressed at the end was 80°C.

[0077] Comparative Example 1 An electrode assembly interleaving roller was manufactured in which the material of the center and end parts was S45C, the heating element was a cartridge-insertion type heater, and the surface temperature of the center and end parts was 80°C.

[0078] Experimental Example 1. Measurement of adhesive strength of electrode assembly The electrodes and separators were laminated using the electrode assembly lamination rollers prepared in Example 1 and Comparative Example 1 to prepare respective electrode assemblies.

[0079] At this time, the overall length of the electrode assembly was the same as the length of the electrode assembly lamination rollers of Example 1 and Comparative Example 1. In addition, the separator and the electrodes were fed in their entire width direction, and the lamination rollers of Example 1 and Comparative Example 1 heated and pressed them to laminate them to prepare the respective electrode assemblies.

[0080] The adhesive strength of the electrode assembly was measured at the center and both ends in the width direction, and the results are shown in Table 1 below.

[0081] (Unit: gf / 20mm) [Table 1]

[0082] When an electrode assembly was manufactured using the interleaving roller of Comparative Example 1, the adhesive strength at both ends was about 77% and 80% of the adhesive strength at the center.

[0083] However, when the electrode assembly was manufactured using the interleaving roller of Example 1, the adhesive strength at both ends was about 90% of that at the center.

[0084] Therefore, it can be seen that the electrode assembly lamination roller according to an embodiment of the present invention can improve the adhesive strength at both ends in the entire width direction of the electrode assembly. [Explanation of symbols]

[0085] 110: Separation membrane roll 111: Separation membrane sheet 120: Electrode roll 121: Electrode 130: Heating and pressurizing section 140, 200: Interleaving roller 151: Electrode assembly 210: Central part 220: End part

Claims

1. An electrode assembly lamination roller for laminating an electrode and a separator, The electrode assembly interleaving roller includes a center portion in a longitudinal direction; and end portions located at both ends of the center portion; The electrode assembly lamination roller includes a heating member therein, The surface temperature of the end portion is higher than the surface temperature of the center portion, The central and distal portions are made of different materials; The material of the distal portion has a higher thermal conductivity than the material of the central portion, and the heating element applies heat to the central portion and the distal portion at the same temperature. Electrode assembly interleaving roller.

2. 2. The electrode assembly lamination roller according to claim 1, wherein the length of the electrode assembly lamination roller corresponds to the overall length of the electrode assembly excluding the tap.

3. 2. The electrode assembly lamination roller according to claim 1, wherein the surface temperature of the end portion is 10 to 30° C. higher than the surface temperature of the center portion.

4. 2. The electrode assembly lamination roller according to claim 1, wherein the surface temperature of the end portion is developed to be 60 to 80.degree. C., and the surface temperature of the center portion is developed to be 40 to 60.degree.

5. An electrode assembly lamination roller as described in claim 1, wherein the thermal conductivity of the material at the end portion is 3 to 20 W / mK higher than the thermal conductivity of the material at the center portion.

6. 2. The electrode assembly lamination roller according to claim 1, wherein the ratio of the length of the center portion to the length of each end portion is 2:1 to 5:

1.

7. 2. The electrode assembly lamination roller according to claim 1, wherein the electrode assembly lamination roller presses and heats the separator and the electrodes fed in the entire width direction of the electrode assembly.

8. The electrode assembly lamination roller of claim 1 , wherein the electrode assembly is a bicell.

9. 2. The electrode assembly lamination roller according to claim 1, wherein the electrode assembly lamination roller comprises a pair including an upper lamination roller and a lower lamination roller.

10. The electrode assembly lamination roller according to claim 9 , wherein the electrode assembly lamination roller comprises one or more pairs.

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