Electrode assembly lamination roll

Abstract

The present invention relates to an electrode assembly lamination roll for laminating an electrode and a separator, wherein the lamination roll comprises, with reference to a length direction: a central portion; and end portions located at both ends of the central portion, wherein a surface temperature of the end portions is exhibited higher than a surface temperature 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, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to an electrode assembly laminating roller for laminating electrodes and diaphragms. Background Technology

[0003] With the development of technology and the increasing demand for mobile devices, the demand for secondary batteries as an energy source has increased dramatically. Therefore, a large amount of research is being conducted on secondary batteries that can meet various needs.

[0004] Generally speaking, in terms of battery shape, there is a greater demand for thin prismatic and pouch-shaped secondary batteries that can be used in products such as mobile phones. In terms of materials, there is a greater demand for lithium secondary batteries such as lithium-ion batteries and lithium-ion polymer batteries that have advantages such as high energy density, high discharge voltage and high output stability.

[0005] Furthermore, secondary batteries are also classified according to the structure of the electrode assembly with a positive electrode / separator / negative electrode structure. Typical examples include: jelly roll (wound type) electrode assemblies having a structure in which a long sheet-type positive electrode and a negative electrode are wound together with a separator inserted between them; stacked electrode assemblies having multiple positive and negative electrodes cut into predetermined size units and sequentially stacked with separators inserted between them; and stacked / folded electrode assemblies, etc. Stacked / folded electrode assemblies have a structure in which a bi-cell or full-cell battery is wound with a separator sheet, formed by stacking predetermined units of positive and negative electrodes with separators inserted between them.

[0006] Electrode assemblies consisting of a positive electrode, a separator, and a negative electrode can have a simple stacked structure, but they can also have a structure in which multiple electrodes (positive and negative electrodes) are stacked with separators inserted between them, and then lamination is performed by heating / pressurization. In this case, lamination of the electrodes and separator is achieved by heating and pressurizing an adhesive layer applied to the separator and electrodes while they are facing each other. Therefore, the separator is usually coated with an adhesive material to improve the adhesion strength to the electrodes.

[0007] In the electrode-diaphragm lamination process, electrodes that have been rolled out and cut are typically placed on a diaphragm sheet. Lamination rollers press and heat the diaphragm sheet and electrodes to adhere them together. With the electrodes attached, the diaphragm sheet is then cut to complete the electrode assembly.

[0008] However, since the thickness of the electrode assembly at both ends in the full width direction is less than that of the central portion, pressure and heating cannot be fully performed compared to the central portion, which may result in a decrease in the adhesive strength at both ends in the full width direction.

[0009] Therefore, there is a high demand for solutions to this problem.

[0010] [Existing Technical Documents]

[0011] [Patent Literature]

[0012] Korean Patent No. 10-1361675

[0013] Korean Patent Application Publication No. 10-2018-0023185. Summary of the Invention

[0014] Technical issues

[0015] As a result of various studies conducted to solve the above-mentioned problems, the inventors of the present invention have confirmed that when the surface temperature of the ends at both ends of the central portion of the laminating roller is higher than the surface temperature of the central portion, the bonding strength of the electrode assembly at both ends in the full width direction can be improved, and thus the present invention has been completed.

[0016] Therefore, the object of the present invention is to provide an electrode assembly laminating roller capable of improving the adhesion strength of the electrode assembly at both ends in the full width direction.

[0017] Technical solution

[0018] To achieve the above objectives, the present invention provides an electrode assembly laminating roller for laminating electrodes and diaphragms.

[0019] The electrode assembly laminating roller, based on its length, includes: a central portion; and end portions located at both ends of the central portion.

[0020] The electrode assembly laminating roller includes a heating element, and

[0021] The surface temperature of the end portion is higher than that of the central portion.

[0022] In one embodiment of the present invention, the length of the electrode assembly laminating roller may have a length corresponding to the length of the electrode assembly in the entire length direction excluding the tabs.

[0023] In one embodiment of the invention, the surface temperature of the end portion may be 10°C to 30°C higher than the surface temperature of the central portion.

[0024] In one embodiment of the invention, the surface temperature of the end portion may be 60°C to 80°C, and the surface temperature of the central portion may be 40°C to 60°C.

[0025] In one embodiment of the invention, the materials of the central portion and the ends may be different from each other.

[0026] In one embodiment of the invention, the material at the end may have a higher thermal conductivity than the material of the central portion.

[0027] In one embodiment of the invention, the heating member may be a heating member that applies heat at the same temperature to the central portion and the end portion, or it may be a heating member that makes the surface temperature of the end portion higher than the surface temperature of the central portion.

[0028] In one embodiment of the invention, the material of the central portion and the material of the ends may be the same.

[0029] In one embodiment of the invention, the heating element may be a heating element that causes the surface temperature of the end portion to be higher than the surface temperature of the central portion.

[0030] In one embodiment of the invention, the ratio of the length of the central portion to the length of each end portion may be from 2:1 to 5:1.

[0031] In one embodiment of the invention, the electrode assembly laminating roller can pressurize and heat the diaphragm and electrode conveyed in the full width direction of the electrode assembly.

[0032] In one embodiment of the present invention, the electrode assembly may be a dual-cell battery.

[0033] In one embodiment of the present invention, the electrode assembly laminating roller may be composed of a pair of rollers including an upper laminating roller and a lower laminating roller.

[0034] In one embodiment of the invention, the electrode assembly laminating roller may include one or more pairs of rollers.

[0035] Beneficial effects

[0036] The electrode assembly laminating roller of the present invention makes the surface temperature of the two ends located at both ends of the central portion higher than the surface temperature of the central portion, thereby improving the problem of deterioration of adhesive strength at both ends of the electrode assembly in the full width direction. Attached Figure Description

[0037] Figure 1 It is a perspective view that schematically illustrates the manufacturing process of the electrode assembly.

[0038] Figure 2This is a perspective view of an electrode assembly laminating roller according to an embodiment of the present invention.

[0039] Figure 3 This is a photo of the electrode assembly. Detailed Implementation

[0040] The invention will now be described in detail with reference to the accompanying drawings, enabling those skilled in the art to readily implement it. However, the invention may be embodied in several different forms and is not limited to the embodiments described herein.

[0041] To clearly explain the invention, parts unrelated to the description of the invention have been omitted, and the same or similar elements are indicated by the same reference numerals throughout the specification.

[0042] Furthermore, the terms and words used in this specification and claims should not be construed as being limited to common or dictionary terms, but should be interpreted as having meanings and concepts consistent with the technical concept of the invention, based on the principle that the inventor can appropriately define the concepts of the terms to best describe his invention.

[0043] Figure 1 It is a perspective view that schematically illustrates the manufacturing process of a typical electrode assembly.

[0044] Figure 1 The manufacturing process of a single cell consisting of an electrode and a separator is shown.

[0045] Reference Figure 1 Electrodes 121, which are taken out and cut from electrode roll 120, are placed on diaphragm sheet 111 taken out from diaphragm roll 110. Electrodes 121 placed on diaphragm sheet 111 are moved to heating and pressurizing zone 130, and diaphragm sheet 111 and electrodes 121 pass through laminating rollers 140 that generate heating and pressurization and thus lamination them, so that electrodes 121 and diaphragm sheet 111 are laminated.

[0046] Then, with the electrode 121 attached, the diaphragm 111 is cut to complete the electrode assembly 151.

[0047] Figure 1 The process of laminating electrode 121 onto diaphragm sheet 111 is shown, but alternatively, it is of course possible to place electrodes on diaphragms that have been cut into unit diaphragms and then laminate them.

[0048] Figure 2 This is a perspective view showing an electrode assembly laminating roller 200 according to an embodiment of the present invention.

[0049] Reference Figure 2According to one embodiment of the present invention, an electrode assembly laminating roller 200 is used to laminate electrodes and diaphragms, and may include a central portion 210 and end portions 220 located at both ends of the central portion 210 in the length direction, and the surface temperature of the end portions 220 may be higher than the surface temperature of the central portion 210.

[0050] Additionally, the laminating roller 200 may include a heating element (not shown).

[0051] As described above, in the manufacturing process of the electrode assembly, the electrodes are placed on the separator. In this case, the length of the separator in its entire width direction is greater than the length of the electrodes in its entire width direction. Therefore, compared with the central portion of the electrode assembly, the two ends of the electrode assembly in its entire width direction cannot be sufficiently heated and pressurized by the laminating rollers. As a result, the lamination of the two ends of the electrode assembly in its entire width direction cannot be properly performed, and the adhesive strength is reduced. In addition, when manufacturing a dual-cell type electrode assembly, the thickness of the two ends of the electrode assembly in its entire width direction is thinner than the thickness of the central portion, thus causing the aforementioned problems.

[0052] Figure 3 This is a photograph of the electrode assembly, where F represents the two ends of the electrode assembly in the full width direction.

[0053] In conventional laminating rollers, the temperature applied to the central portion of the laminating roller is the same as the temperature applied to the ends located at both ends of the central portion, and the material of the central portion and the ends is also the same, so the above problem cannot be solved.

[0054] Therefore, the electrode assembly laminating roller 200 according to one embodiment of the present invention aims to solve the problem of deterioration of adhesive strength at both ends of the electrode assembly in the full width direction by making the surface temperature of the end portion 220 higher than that of the central portion 210, so that a higher temperature is applied to both ends of the electrode assembly in the full width direction than to the central portion.

[0055] Therefore, the surface temperature of the end portion 220 can be 10°C to 30°C higher than the surface temperature of the central portion 210. Within this temperature range, the adhesive strength of the electrode assembly at both ends in the full width direction can be improved.

[0056] If the surface temperature of the end portion 220 is less than 10°C higher than the surface temperature of the central portion 210, the effect of improving the adhesion strength of the electrode assembly at both ends in the full width direction is not significant. If the surface temperature of the end portion 220 is more than 30°C higher than the surface temperature of the central portion 210, the adhesive material in the diaphragm may melt and block the pores of the diaphragm.

[0057] The surface temperature of the end portion 220 can be between 60°C and 80°C, and the surface temperature of the central portion 210 can be between 40°C and 60°C.

[0058] The materials of the central portion 210 and the end portion 220 may be different from each other, and the material of the end portion 220 may be a material with a higher thermal conductivity than the material of the central portion 210. Specifically, the thermal conductivity of the material of the end portion 220 may be 3 W / mK to 20 W / mK higher than that of the material of the central portion 210.

[0059] For example, the material of the end portion 220 can be carbon steel for mechanical structures or carburizing steel, such as S45C or S50C. Similarly, the material of the central portion 210 can be carbon steel for mechanical structures, such as S45C or S15CK.

[0060] The thermal conductivity of S45C is 49.8 W / mK, that of S50C is 52 W / mK, and that of S15CK is 32 W / mK.

[0061] If the thermal conductivity of the material at the end 220 is higher than that of the material at the center 210, the heating element may be a heating element that applies the same temperature to the center 210 and the end 220, or it may be a heating element that makes the surface temperature of the end 220 appear higher than that of the center 210.

[0062] When the heating element applies the same temperature to the central portion 210 and the end portion 220, the surface temperature of the end portion 220 can be higher than that of the central portion 210 because the material of the end portion 220 has a higher thermal conductivity than that of the material of the central portion 210. In this case, the electrode assembly laminating roller 200 may include a heating element. Therefore, heat is linearly distributed on the electrode assembly laminating roller 200, so that a rapid surface temperature difference is not generated at each location of the electrode assembly, thereby preventing damage to the electrode assembly due to temperature differences.

[0063] In addition, the material of the end portion 220 and the material of the central portion 210 can be the same.

[0064] If the material of the end portion 220 and the material of the central portion 210 are the same, the heating element can be a heating element that makes the surface temperature of the end portion 220 appear higher than the surface temperature of the central portion 210.

[0065] If the heating element is one that causes the surface temperature of the end 220 to be higher than the surface temperature of the central portion 210, then heating elements with different calorific values ​​can be used inside the end 220 and the central portion 210. That is, the heating element included in the end 220 may have a higher calorific value than the heating element included in the central portion 210.

[0066] In this case, multiple heating elements with different calorific values ​​can be used, or a single heating element can be used that provides different calorific values ​​depending on the positions of the end 220 and the central portion 210. However, in the above case, there may not be enough space within the electrode assembly laminating roller 200 to insert multiple heating elements. To insert multiple heating elements, sufficient space must be ensured within the end 220 and the central portion 210, which requires expanding the blanking space within the end 220 and the central portion 210. As the blanking space increases, the weight of the laminating roller 200 decreases, and therefore, due to the reduced pressure applied to the electrodes and diaphragms, lamination of the electrodes and diaphragms may not be possible. Furthermore, there are problems such as increased manufacturing complexity and the potential for damage to the electrode assembly due to the sharp temperature difference applied to the central portion and both ends of the electrode assembly.

[0067] Therefore, in the electrode assembly laminating roller 200, it is most preferable that the materials of the end portion 220 and the central portion 210 are different from each other, the material of the end portion 220 has a higher thermal conductivity than the material of the central portion 210, and the heating member can apply heat at the same temperature to the central portion 210 and the end portion 220.

[0068] The heating element can be a cylinder insertion heater, a sheath heater, or an induction heater, but is not limited to these.

[0069] The sheath heater heats the outer casing using radiant heat by winding a coil around the core. For example, when the sheath heater is used as the heating element, the number of coil windings differs in the region of the central portion 210 and the region of the end 220, so that the temperatures generated on the surface of the central portion 210 and the surface of the end 220 can be controlled to be different from each other.

[0070] The electrode assembly can be a single cell consisting of one electrode and one separator, a mono-cell having a separator inserted between the positive and negative electrodes, or a bi-cell having two separators inserted between three electrodes having different polarities from the adjacent electrodes. The single and bi-cells can include types in which separators are further added to the side of the electrodes that does not face the separator inserted between the electrodes.

[0071] Specifically, a dual-cell battery is a battery in which the same electrode is located on the outermost side. Examples include a single-cell battery with a positive electrode / separator / negative electrode / separator / positive electrode structure, and a single-cell battery with a negative electrode / separator / positive electrode / separator / negative electrode structure. A single-cell battery with a positive electrode / separator / negative electrode / separator / positive electrode structure is defined as a "type A dual-cell battery," and a single-cell battery with a negative electrode / separator / positive electrode / separator / negative electrode structure is defined as a "type C dual-cell battery." That is, a dual-cell battery with a negative electrode at its center is called a type A dual-cell battery, and a dual-cell battery with a positive electrode at its center is called a type C dual-cell battery.

[0072] There are no particular restrictions on the type of electrode assembly, but dual cells are preferred.

[0073] Additionally, the electrode assembly may include tabs; more specifically, the positive electrode may include a positive tab, and the negative electrode may include a negative tab.

[0074] The length of the laminating roller 200 may be the same as the length of the electrode assembly in the entire length direction, excluding the tabs.

[0075] Specifically, the length of the laminating roller 200 is equal to the length of the electrode assembly in the entire length direction excluding the tabs, or it can be 1 to 1.1 times, preferably 1 to 1.05 times, the length of the electrode assembly in the entire length direction excluding the tabs.

[0076] Furthermore, the ratio of the length of the central portion 210 to the length of the end portion 220 can be from 2:1 to 5:1.

[0077] In the electrode assembly, the thickness at both ends along the full width is thinner than that of the central portion, resulting in a deterioration in adhesive strength at the ends along the full width. Therefore, to solve this problem, an electrode assembly laminating roller 200 according to an embodiment of the present invention can pressurize and heat the diaphragm and electrode conveyed along the full width of the electrode assembly.

[0078] The diaphragm and electrodes are conveyed along the full width direction, so the end of the laminating roller 200 contacts both ends of the diaphragm and electrodes in the full width direction, and by heating and pressurizing them, the problem of deterioration of adhesive strength at both ends in the full width direction can be improved.

[0079] In conventional electrode assembly laminating rollers, the adhesive strength at both ends in the full width direction is 70% to 80% of the adhesive strength at the central portion of the electrode assembly. However, in the electrode assembly laminating roller 200 according to an embodiment of the present invention, the adhesive strength at both ends in the full width direction can be 85% to 95% of the adhesive strength at the central portion of the electrode assembly. That is, the electrode assembly laminating roller 200 according to an embodiment of the present invention can improve the adhesive strength at both ends of the electrode assembly in the full width direction.

[0080] Furthermore, the laminating roller 200 may be composed of a pair of rollers including an upper laminating roller and a lower laminating roller, and the laminating roller may be one or more pairs of rollers.

[0081] For example, the laminating roller 200 may consist of two or more pairs of rollers, and n laminating rollers 200 may be arranged from the first laminating roller through which the electrode and diaphragm first pass to the nth laminating roller arranged in sequence.

[0082] Furthermore, the laminating roller 200 can be in a form that allows setting the time for pressurizing and heating the electrodes and the diaphragm, and also allows adjustment of the rotation speed.

[0083] Those skilled in the art will understand that these embodiments can be implemented in modified ways without departing from the essential characteristics described above. Therefore, the disclosed methods should be considered illustrative rather than restrictive. The scope of the invention is shown by the claims rather than the foregoing description, and all differences within the equivalent scope will be construed as included in the invention.

[0084] Mode of implementing the present invention

[0085] Preferred examples are provided below to aid in understanding the invention. However, the following examples are merely illustrative, and it will be apparent to those skilled in the art that various changes and modifications can be made within the scope and spirit of the invention, which of course fall within the scope of the appended claims.

[0086] <Manufacturing of Electrode Assembly Laminating Rollers>

[0087] Example 1.

[0088] A laminating roll is manufactured with the length direction of the laminating roll as a reference, including a central portion and ends located at both ends of the central portion.

[0089] The roller is manufactured using S15CK as the material for the central part and S45C as the material for the ends, and a cylinder-insertion type heater is used as the heating element.

[0090] At this point, the ratio of the length of the central portion to the length of each end is 3:1, and the surface temperature exhibited in the central portion is 60°C, while the surface temperature exhibited in the ends is 80°C.

[0091] Comparative Example 1.

[0092] The electrode assembly laminating roller is manufactured using S45C as the material for both the central and end portions. The heating element is a cylindrical insert heater, and the surface temperature of both the central and end portions is 80°C.

[0093] Experimental Example 1. Measurement of the Adhesion Strength of Electrode Assemblies

[0094] Each electrode assembly was prepared by laminating electrodes and diaphragms using the electrode assembly lamination rollers prepared in Example 1 and Comparative Example 1 described above.

[0095] At this point, the length of the electrode assembly in its entire length direction is the same as the length of the laminating rollers for the electrode assemblies of Example 1 and Comparative Example 1. Furthermore, the diaphragm and electrodes are conveyed along their entire width direction, and the laminating rollers of Example 1 and Comparative Example 1 heat and pressurize them to laminate them, thereby preparing each electrode assembly.

[0096] The adhesive strength of the central portion and both ends in the full width direction of the prepared electrode assembly was measured, and the results are shown in Table 1 below.

[0097] [Table 1]

[0098] (Unit: gf / 20mm)

[0099] Example 1 22.3 24.781 22.3 Comparative Example 1 19.165 24.781 19.902

[0100] When the electrode assembly was manufactured using the laminating roller of Comparative Example 1, the adhesive strength at both ends showed approximately 77% and 80% of the adhesive strength at the central portion.

[0101] However, when the electrode assembly was manufactured using the laminating roller of Example 1, the adhesive strength at both ends showed approximately 90% of the adhesive strength at the central portion.

[0102] It can be seen that the electrode assembly laminating roller according to one embodiment of the present invention can improve the bonding strength of the electrode assembly at both ends in the full width direction.

[0103] [Explanation of Symbols]

[0104] 110: Diaphragm roll; 111: Diaphragm sheet

[0105] 120: Electrode roll 121: Electrode

[0106] 130: Heating and pressurizing section

[0107] 140, 200: Laminating rollers

[0108] 151: Electrode assembly; 210: Central section

[0109] 220: End.

Claims

1. A laminating roller for laminating electrodes and diaphragms, The electrode assembly laminating roller, taken along its length, includes: The central portion; and the ends located at both ends of the central portion. The electrode assembly laminating roller includes a heating element, and The materials of the central portion and the ends are different from each other, the material of the ends has a higher thermal conductivity than the material of the central portion, and the heating member applies heat of the same temperature to the central portion and the ends, such that the surface temperature of the ends is higher than that of the central portion.

2. The electrode assembly laminating roller according to claim 1, wherein the length of the electrode assembly laminating roller has a length corresponding to the length of the electrode assembly in the entire length direction excluding the tabs.

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

4. The electrode assembly laminating roller according to claim 1, wherein the surface temperature of the end portion is 60°C to 80°C, and the surface temperature of the central portion is 40°C to 60°C.

5. The electrode assembly laminating roller of claim 1, wherein the ratio of the length of the central portion to the length of each end portion is 2:1 to 5:

1.

6. The electrode assembly laminating roller of claim 1, wherein the electrode assembly laminating roller pressurizes and heats the diaphragm and electrode conveyed in the full width direction of the electrode assembly.

7. The electrode assembly laminating roller according to claim 1, wherein the electrode assembly is a dual-cell battery.

8. The electrode assembly laminating roller according to claim 1, wherein the electrode assembly laminating roller is composed of a pair of rollers including an upper laminating roller and a lower laminating roller.

9. The electrode assembly laminating roller of claim 8, wherein the electrode assembly laminating roller comprises one or more pairs of rollers.

Images