Electrode assembly, method for manufacturing the same, and battery cell including the same

Abstract

An electrode assembly according to one embodiment of the present invention includes a cell stack in which electrodes and separators are alternately stacked, an adhesive layer formed on a side of the cell stack, and a finishing separator surrounding the cell stack on which the adhesive layer is formed, the adhesive layer including a laser-absorbing adhesive.

Description

Technical Field

[0001] Cross-reference to Related Application(s) This application claims the benefit of priority based on Korean Patent Application Nos. 10-2021-0173204 filed on Dec. 06, 2021 and 10-2022-0165842 filed on Dec. 01, 2022, and all of the contents disclosed in the documents of the Korean patent applications are incorporated herein by reference in their entirety.

[0002] The present invention relates to an electrode assembly, a method of manufacturing the same, and a battery cell including the same, and more particularly, to an electrode assembly having complementary rigidity, a method of manufacturing the same, and a battery cell including the same.

Background Art

[0003] In modern society, the use of portable devices such as mobile phones, notebook computers, camcorders, and digital cameras has become common, and the development of technologies in fields related to such mobile devices has been actively carried out. In addition, rechargeable secondary batteries are a solution for solving air pollution such as existing gasoline vehicles that use fossil fuels, and are used as power sources for electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (P-HEVs), etc., and the need for the development of secondary batteries is increasing.

[0004] Currently, commercially available secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, lithium secondary batteries, etc. Among these, lithium secondary batteries are most notable for their advantages of free charge and discharge, low self-discharge rate, and high energy density.

[0005] Secondary batteries are classified into cylindrical batteries and prismatic batteries in which an electrode assembly is installed in a cylindrical or prismatic metal can according to the shape of the battery case, and pouch-type batteries in which an electrode assembly is installed in a pouch-type case of an aluminum laminate sheet.

[0006] In addition, secondary batteries may be classified according to the structure of the electrode assembly in which a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode are laminated. Typically, there are a jelly-roll type (winding type) electrode assembly in which a long sheet-type positive electrode and negative electrode are wound with a separator interposed therebetween, and a stack type (laminated type) electrode assembly in which a plurality of positive electrodes and negative electrodes cut out in units of a predetermined size are sequentially laminated with a separator interposed therebetween. In recent years, in order to solve the problems of the jelly-roll type electrode assembly and the stack type electrode assembly, a stack / folding type electrode assembly having a mixed shape of the jelly-roll type and the stack type has been developed.

[0007] FIG. 1 is a drawing showing a state in which the electrode assembly hangs down due to gravity.

[0008] The electrode assembly 10 is formed as a stack type electrode assembly mainly by laminating a positive electrode, a separator, a negative electrode, and a separator, or by sequentially laminating a negative electrode, a separator, a positive electrode, and a separator. After the above-described stacking process, the electrode assembly 10 is transferred for welding of the electrode tab and welding of the electrode tab - electrode lead. At this time, due to the size and weight of the electrode assembly 10, a sagging phenomenon as shown in FIG. 1 may occur in the electrode assembly 10.

[0009] When a sagging phenomenon occurs in the electrode assembly 10, it becomes difficult to transfer the electrode assembly 10 for subsequent processes, and there is a possibility that defects may occur in the battery cells manufactured through the subsequent processes. Conventionally, a method of complementing the stiffness of the electrode assembly 10 has been devised by pressing the electrode assembly 10 or laminating each unit cell forming the electrode assembly. However, the above-described method cannot be applied to inexpensive separators, and thus has a problem that it cannot be applied to various products. Summary of the Invention Problems to be Solved by the Invention

[0010] The problem to be solved by the present invention is to provide an electrode assembly with improved overall rigidity of the electrode assembly and a battery cell including the same.

[0011] However, the problems to be solved by the embodiments of the present invention are not limited to the above-described problems, and can be variously extended within the scope of the technical idea included in the present invention.

Means for Solving the Problems

[0012] An electrode assembly according to an embodiment of the present invention includes a cell laminate in which electrodes and a separator are alternately laminated, an adhesive layer formed on a side surface of the cell laminate, and a finishing separator that wraps around the cell laminate on which the adhesive layer is formed, and the adhesive layer includes a laser-absorbing adhesive.

[0013] The laser-absorbing adhesive may include a laser marking substance that reacts to a laser.

[0014] The laser marking substance can absorb the energy of the laser that has passed through the finishing separator.

[0015] The laser marking substance may include SnO 2 (tin oxide)-based substances.

[0016] The laser marking substance may further include a doping substance of Sb (antimony) and / or In (indium) doped in the SnO 2 (tin oxide)-based substance.

[0017] The average particle size value of the laser marking substance can correspond to the wavelength value of the laser.

[0018] The adhesive layer can be formed on a side surface of the cell laminate where the long side of the separator is located.

[0019] The separation membrane can have a zigzag shape formed by folding a rectangular sheet.

[0020] A method for manufacturing an electrode assembly according to another embodiment of the present invention includes forming a cell laminate in which electrodes and a separation membrane are alternately laminated, applying an adhesive to the side surface of the cell laminate, wrapping a finishing separation membrane around the cell laminate to which the adhesive has been applied, irradiating a laser to the outside of the finishing separation membrane, and forming an adhesive layer by curing the adhesive with the laser.

[0021] The wavelength value of the laser can be selected according to the characteristics of the finishing separation membrane.

[0022] The adhesive can contain a laser marking substance that reacts to the laser.

[0023] The cell laminate can include a zigzag-shaped separation membrane.

[0024] A battery cell according to another embodiment of the present invention includes the above-described electrode assembly.

Advantages of the Invention

[0025] According to the embodiment, the electrode assembly, the manufacturing method thereof, and the battery cell including the same of the present invention can improve the overall rigidity by including adhesive layers on both sides of the electrode assembly.

[0026] The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0028] Hereinafter, with reference to the accompanying drawings, various embodiments of the present invention will be described in detail so that those having ordinary knowledge in the technical field to which the present invention pertains can easily implement them. The present invention can be implemented in various forms other than those described below and is not limited to the embodiments described here.

[0029] To clearly explain the present invention, unnecessary parts in the description are omitted, and the same reference numerals are assigned to the same or similar components throughout the specification.

[0030] Also, the size and thickness of each configuration shown in the drawings are arbitrarily enlarged or reduced for the convenience of explanation, and it is obvious that the present invention is not necessarily limited to what is shown. In the following drawings, the thickness is enlarged to clearly represent a plurality of layers and regions. And in the following drawings, for the convenience of explanation, the thickness of some layers and regions is exaggerated.

[0031] Also, when a part such as a layer, film, region, or plate is "on" or "above" another part, this includes not only the case where the part such as the layer, film, region, or plate is directly above the other part, but also the case where there is another part in between. Conversely, when a part is "directly above" another part, it means that there is no other part in between. Also, being "on" or "above" a reference part means being located above or below the reference part, and does not necessarily mean being located "on" or "above" in the direction opposite to gravity. On the other hand, similar to explaining that a part is "on" or "above" another part, the meaning of a part being "below" or "beneath" another part should also be understood with reference to the above description.

[0032] Also, throughout the specification, when a part "includes" a certain component, this means that, unless otherwise specified to the contrary, it does not exclude other components but can further include other components.

[0033] Also, throughout the specification, when it is said "on a plane", this means when looking at the target part from above, and when it is said "in a cross-section", this means when looking at the cross-section obtained by vertically cutting the target part from the side.

[0034] Hereinafter, an electrode assembly according to an embodiment of the present invention will be described.

[0035] FIG. 2 is a drawing showing an electrode assembly according to an embodiment of the present invention.

[0036] Referring to FIG. 2, the electrode assembly 100 of this embodiment can include an electrode (positive electrode 110, negative electrode 120) and a separator 130 as a power generation element capable of charge and discharge. The electrodes 110, 120 included in the electrode assembly 100 can include a positive electrode 110 and a negative electrode 120. By interposing a separator 130 between each electrode (positive electrode 110, negative electrode 120), the electrode assembly 100 can have a structure in which the positive electrode 110 / separator 130 / negative electrode 120 are alternately laminated. Here, the positions of the positive electrode 110 and the negative electrode 120 shown in FIG. 2 are shown for convenience, and their positions can be mutually changed.

[0037] Here, the separator 130 can also have a zigzag shape formed by bending a rectangular separator sheet. That is, the electrode assembly 100 of this embodiment can be formed by sequentially laminating electrodes (positive electrode 110, negative electrode 120) and a separator 130 cut to a predetermined size, but it may also be formed by interposing the positive electrode 110 or the negative electrode 120 between the separators 130 bent in a zigzag shape. More specifically, the separator 130 can be folded in a direction covering the positive electrode 110 in a state where the positive electrode 110 is laminated, and can be folded in a direction covering the negative electrode 120 in a state where the negative electrode 120 is laminated on the separator 130 covering the positive electrode 110. Then, in a state where the positive electrode 110 is laminated on the separator 130 covering the negative electrode 120, the separator 130 can be folded in a direction covering the positive electrode 110. In this way, the electrode assembly 100 can be formed by repeating the lamination of the electrodes (positive electrode 110, negative electrode 120) and the folding of the separator 130.

[0038] On the one hand, in order to prevent the sagging phenomenon of the electrode assembly 100, conventionally, there have been attempts to complement the rigidity of the electrode assembly 100 through a pressing process or a laminating process. However, when the separator 130 used in the electrode assembly 100 is an inexpensive separator, the application of the above-described processes is impossible. Even when the application is possible, there has been a problem that the electrode assembly 100 is damaged by a pressing process or a laminating process that applies pressure or heat.

[0039] However, the electrode assembly 100 of the present embodiment can complement the rigidity of the electrode assembly 100 by including an adhesive layer 140 formed on the side surface. The electrode assembly 100 of the present embodiment can improve the rigidity of the electrode assembly 100 while omitting the process of applying pressure or heat to the electrode assembly 100, and can also include an inexpensive separator.

[0040] The adhesive layer 140 can be formed on the side surface of the cell laminate 101 (see FIG. 3) in which the electrodes (positive electrode 110, negative electrode 120) and the separator 130 are alternately laminated. Here, the cell laminate 101 may mean a laminate of the electrodes (positive electrode 110, negative electrode 120) and the separator 130 in the electrode assembly 100 of the present embodiment. Also, here, the side surface of the cell laminate 101 can refer to a surface on which the ends of the plurality of electrodes (positive electrode 110, negative electrode 120) and / or the separator 130 are exposed in the cell laminate 101 in which the electrodes (positive electrode 110, negative electrode 120) and the separator 130 are alternately laminated.

[0041] The adhesive layer 140 can be in contact with the separator 130. When manufacturing the electrode assembly 100, the size of the separator 130 can be provided larger than the size of the electrodes (positive electrode 110, negative electrode 120), and the end portion of the separator 130 can protrude beyond the ends of the electrodes (positive electrode 110, negative electrode 120). Here, the protruding end portion of the separator 130 can be referred to as an "extension portion 138 (see FIG. 3)".

[0042] Also, even when the electrode assembly 100 is formed through a zigzag lamination, the end portion of the separator 130 can protrude beyond the ends of the electrodes (the positive electrode 110 and the negative electrode 120). In the electrode assembly 100 formed through a zigzag lamination, one of the two ends of the electrodes (the positive electrode 110 and the negative electrode 120) may be covered by the separator 130, and the other end may not be covered by the separator 130. At this time, when the sizes of the positive electrode 110 and the negative electrode 120 are different, extension portions 138 are likely to be formed on the upper and lower surfaces of the electrode (the positive electrode 110 and the negative electrode 120) with a relatively smaller size. Alternatively, a part of the separator 130 covering the end of the electrode (the positive electrode 110 and the negative electrode 120) may be referred to as the extension portion 138.

[0043] When the extension portion 138 is formed on the separator 130, the adhesive layer 140 can fix the shape of the separator 130 by contacting the extension portion 138 of the separator 130 that does not contact the electrodes (the positive electrode 110 and the negative electrode 120). The separator 130 and other separators 130 adjacent thereto can be fixed to each other by the adhesive layer 140.

[0044] On the other hand, in FIG. 2, the adhesive layer 140 is illustrated as contacting the positive electrode 110, but there may be cases where it is preferable that the adhesive layer 140 does not contact the positive electrode 110. This is because the flow of ions moving from the positive electrode 110 to the negative electrode 120 is blocked by the adhesive layer 140. Also, although it is preferable that the adhesive layer 140 does not contact the negative electrode 120, since the negative electrode 120 is not a direct charging region, the influence may be less than when the positive electrode 110 and the adhesive layer 140 are in contact.

[0045] The adhesive layer 140 can be formed on all side surfaces of the electrode assembly 100, but there may be cases where it is preferable to form it only on some side surfaces. This is because when the adhesive layer 140 is formed on all side surfaces of the electrode assembly 100, gas release from the electrode assembly 100 is blocked by the adhesive layer 140 during the impregnation or activation process of the electrolyte in the electrodes (the positive electrode 110 and the negative electrode 120).

[0046] The adhesive layer 140 may be formed to entirely cover one side surface of the electrode assembly 100, or may be formed to partially cover the side surface. When the adhesive layer 140 does not entirely cover the side surface of the electrode assembly 100, it is possible to prevent the gas emission of the electrode assembly 100 from being obstructed by the adhesive layer 140 during the impregnation or activation process of the electrolyte of the electrodes (positive electrode 110, negative electrode 120).

[0047] The adhesive layer 140 can be formed on the surface of the side of the electrode assembly 100 or the cell stack 101 where the long sides of the electrodes (positive electrode 110, negative electrode 120) or the separator 130 are located. The adhesive layer 140 can be formed on the long sides of the electrodes (positive electrode 110, negative electrode 120) or the separator 130. This is because sagging phenomena and the like occur more frequently along the long sides, which are relatively longer than the short sides of the electrodes (positive electrode 110, negative electrode 120) or the separator 130. However, such an explanation does not completely exclude the possibility that the adhesive layer 140 may be formed on the short sides of the electrodes (positive electrode 110, negative electrode 120) or the separator 130.

[0048] On the other hand, when the adhesive layer 140 is formed on the side surface of the cell stack 101, one surface of the adhesive layer 140 is in contact with the cell stack 101, but the other surface of the adhesive layer 140 has no contact surface in contact with it and may be relatively weak in rigidity. As a result, the effect of the adhesive layer 140 may not be fully exerted.

[0049] The electrode assembly 100 of the present embodiment may include a finishing separator 150 that provides an adhesive surface to the adhesive layer 140 and complements the overall rigidity of the electrode assembly 100. The finishing separator 150 can wrap around the cell stack 101. The finishing separator 150 can surround the side surface of the cell stack 101 once by entirely surrounding the cell stack 101 once. Also, the finishing separator 150 can surround the side surface of the cell stack 101 two or more times by surrounding the cell stack 101 two or more times.

[0050] The finished separation membrane 150 may be the same as the above-described separation membrane 130. For example, when manufacturing the electrode assembly 100 using the zigzag lamination method, the separation membrane 130 folded to cover the outermost corner electrodes (positive electrode 110, negative electrode 120) is finally cut to match a predetermined size. Before cutting the separation membrane 130, the separation membrane 130 can rotate once around the cell laminate 101 and wrap it. At this time, the separation membrane 130 that wraps around the cell laminate 101 can be referred to as the finished separation membrane 150.

[0051] The finished separation membrane 150 can be located outside the adhesive layer 140. The finished separation membrane 150 can be fixed to the cell laminate 101 by the adhesive layer 140. One surface of the adhesive layer 140 can contact the cell laminate 101, and the other surface of the adhesive layer 140 can contact the finished separation membrane 150. By the adhesive layer 140 being located between the cell laminate 101 and the finished separation membrane 150, one surface of the adhesive layer 140 is supported by the cell laminate 101, and the other surface is supported by the finished separation membrane 150. As a result, the effect of the adhesive layer 140 in improving the rigidity and durability of the electrode assembly 100 can be more significantly manifested.

[0052] On the other hand, the adhesive layer 140 can be formed by applying an adhesive such as an adhesive resin. However, when the adhesive is a substance that cures at room temperature, it may cure immediately after application, resulting in a problem that the adhesive layer 140 cannot be adhered to the finished separation membrane 150. Therefore, the adhesive layer 140 in this embodiment can cure after the finished separation membrane 150 surrounds the cell laminate 101, thereby forming an adhesive surface between the cell laminate 101 and the adhesive layer 140 or between the adhesive layer 140 and the finished separation membrane 150. However, in the above-described case, since the adhesive layer 140 is covered by the finished separation membrane 150, there may be limitations in the curing method of the adhesive layer 140. For example, UV may not be able to penetrate the finished separation membrane 150, and in such a case, the use of a UV-curable adhesive may not be possible.

[0053] A laser can be used to cure the adhesive layer 140 of this embodiment, and the wavelength of the laser, etc. can be selected according to the characteristics of the finish separation film 150. The wavelength or output of the laser can penetrate the finish separation film 150 and can be selected within a range that does not damage the finish separation film 150.

[0054] A laser-absorbing adhesive that absorbs the laser and activates or cures the adhesive components by the laser is used for the adhesive layer 140. The laser-absorbing adhesive can contain a laser marking substance that reacts to the laser. The laser marking substance can be activated by a laser of a specific wavelength. When the laser marking substance is activated, heat may be generated, and the adhesive components of the adhesive can be activated or the adhesive can be cured by such heat. Thus, the laser marking substance can act as an initiator. By curing the adhesive through the laser, the side surface of the cell laminate 101 and the finish separation film 150 can be fixed to each other and can adhere to each other by the adhesive layer 140.

[0055] On the other hand, after the laser-absorbing adhesive used for the adhesive layer 140 is applied to the side surface of the cell laminate 101, there may be a predetermined time interval until the finish separation film 150 wraps around the cell laminate 101, and thereby the adhesive in the uncured state may flow in the direction of gravity. Therefore, the laser-absorbing adhesive used in this embodiment can be provided in a high-viscosity state in order to prevent it from flowing after application, and for example, it can have a viscosity of 90,000 to 110,000 cP at 25°C.

[0056] The laser-absorbing adhesive used for the subsequent layer 140 can be manufactured using an adhesive polymer, an organic solvent, and a laser marking substance as starting materials. The laser-absorbing adhesive can contain 0.1 to 0.5 parts by weight of the laser marking substance based on 50 parts by weight of the adhesive polymer. When the content of the laser marking substance is less than 0.1 part by weight, the laser absorption amount of the laser-absorbing adhesive is low, making it difficult to cure the adhesive or activate the adhesive components. When the content exceeds 0.5 part by weight, the dispersibility of the laser marking substance and the resin may decrease, or the viscosity of the electrolytic solution may increase due to the laser marking substance.

[0057] Also, the type of the laser marking substance contained in the adhesive layer 140 can be selected according to the wavelength value of the laser used for curing the adhesive layer 140. The laser marking substance can be selected to have an average particle size value similar to the wavelength value of the laser used. The average particle size value of the laser marking substance can correspond to the laser wavelength value. Here, "correspond" means that even if the laser wavelength value and the average particle size value do not completely match, as long as there is an error within a predetermined range, for example, within a range of 100 nm, it can be described as "corresponding". As a specific example, when the wavelength value of the laser is 900 nm to 1200 nm, the laser marking substance can be selected to have an average particle size of 800 nm to 1300 nm.

[0058] Hereinafter, a method for manufacturing an electrode assembly according to an embodiment of the present invention will be described.

[0059] FIG. 3 and FIG. 4 are drawings showing the manufacturing process of an electrode assembly according to an embodiment of the present invention. FIG. 5 is a flowchart of a method for manufacturing an electrode assembly according to an embodiment of the present invention.

[0060] Referring to FIGS. 3 to 5, the method (S1000) for manufacturing the electrode assembly of this embodiment is as follows: Forming a cell laminate 101 in which electrodes (positive electrode 110, negative electrode 120) and a separator 130 are alternately laminated (S1100); The step of applying the adhesive 142 to the side surface of the cell laminate 101 (S1200), The step of wrapping the cell laminate 101 coated with the adhesive 142 with the finish separation film 150 (S1300), The step of irradiating a laser to the outside of the finish separation film 150 (S1400) and The step of forming the adhesive layer 140 by curing the adhesive 142 with the laser (S1500) can be included.

[0061] The step of forming the cell laminate 101 (S1100) may use any known method as long as the electrodes and the separation film are laminated in the order of the positive electrode 110, the separation film 130, the negative electrode 120, the separation film 130, or in the order of the negative electrode 120, the separation film 130, the positive electrode 110, the separation film 130. For example, the cell laminate 101 can also be manufactured in a stack type or in a zigzag shape. The step (S1100) can be described with reference to "step1" in FIG. 3.

[0062] In the step of applying the adhesive 142 to the side surface of the cell laminate 101 (S1200), any known method can be used for the application method of the adhesive 142. For example, the adhesive 142 can be applied pneumatically or piezoelectrically. Also, the adhesive 142 can be applied in a dot shape through a spot coating method or in a line shape through a line coating method. On the other hand, in order to prevent the applied adhesive 142 from flowing, the adhesive 142 can be provided in a high viscosity state, for example, it can also have a viscosity of 90,000 to 110,000 cP at 25°C. The step (S1200) can be described with reference to "step2" in FIG. 3.

[0063] In the step (S1300) where the finished separator 150 wraps around the cell laminate 101 coated with the adhesive 142, the finished separator 150 may be the same as the separator 130. For example, when the cell laminate 101 is formed through a zigzag lamination method, after the separator 130 covers one side of the outermost electrodes (the positive electrode 110 and the negative electrode 120), it can wrap around the cell laminate 101 before being cut. At this time, the separator 130 that wraps around the cell laminate 101 can be referred to as the finished separator 150. In the process of the finished separator 150 wrapping around the cell laminate 101, a force stronger than a certain level can be applied to the laminate (the cell laminate 101), whereby the adhesive 142 can be stably positioned between the cell laminate 101 and the finished separator 150. The steps (S1300) and (S1400) can be described with reference to "step3" in FIG. 3.

[0064] In the step (S1400) of irradiating the outside of the finished separator 150 with a laser, the wavelength value of the laser and the like can be selected according to the characteristics of the finished separator 150. The wavelength or output of the laser can be selected within a range that can pass through the finished separator 150 but does not damage the finished separator 150.

[0065] For example, in the case of an SRS separator in which the separator contains alumina (Al 3 O 2 ), since alumina may scatter or reflect light, it is appropriate to use a laser having a wavelength of 900 nm or more or a laser having a wavelength of 900 nm to 1200 nm. Also, in the case of a normal adhesive, since it does not react to a laser having a wavelength value of 900 nm or more or a laser having a wavelength of 900 nm to 1200 nm, the adhesive 142 used in this embodiment can contain a laser marking substance that reacts to a laser having a wavelength value of 900 nm or more or a laser having a wavelength of 900 nm to 1200 nm. The adhesive according to this embodiment needs to ensure a certain level of transparency of the adhesive polymer to be applied to the battery cell. For example, the laser marking substance that reacts to a laser having a wavelength of 900 nm to 1200 nm may be a SnO 2 (tin oxide)-based substance. In this way, SnO 2(Tin Oxide)-based materials with Sb (antimony), In (indium), etc. doped in small amounts into SnO 2 can enhance the laser absorption efficiency for light in the range of 900 nm to 1200 nm.

[0066] At the stage (S1500) where the adhesive layer 140 is formed by curing the adhesive 142 with a laser, the laser marking substance contained in the adhesive 142 can absorb the energy of the irradiated laser. By absorbing the energy, the adhesive component of the adhesive 142 can be manifested, and thereby the side surface of the cell laminate 101 can be sealed. The stage (S1500) can be described with reference to "step4" in FIG. 3.

[0067] Hereinafter, an experiment for confirming the characteristics of the laser that can be used in the production of the electrode assembly of this embodiment will be described.

[0068] FIG. 6 is a graph showing the optical characteristics of the separation membrane included in the electrode assembly of an embodiment of the present invention.

[0069] Referring to FIG. 6, when the separation membrane 130 of this embodiment is an SRS separation membrane, the absorbance and reflectance corresponding to the wavelength value of the light source can be confirmed. As described above, the SRS separation membrane contains alumina, and light can be scattered or reflected by the alumina. However, when the SRS separation membrane is used in this embodiment, it is appropriate to use a light source having a wavelength of 900 nm or more or 900 nm to 1200 nm.

[0070] When referring to the reflectance graph in FIG. 6, it can be confirmed that when a 980 nm laser is used, about 40% of the light passes through the SRS separation membrane at 100% output. Based on this, in this experiment, a 980 nm laser was used as the light source, and it was confirmed whether damage occurred to the separation membrane due to the output level and energy level.

[0071]

Table 1

[0072] Referring to the experimental results in Table 1, it was confirmed that the separation membrane was damaged by the energy level of the 980 nm laser. Here, the line energy is the value obtained by dividing the laser output (J / s) by the scan speed (mm / s). Also, here, the 25% output or 35% output is obtained by adjusting the scan speed of the laser to set the line energy value in Table 1, and it is also possible that the 35% output uses higher output energy than the 25% output.

[0073] Specifically, when using a laser having a wavelength of 980 nm, in order to prevent damage to the separation membrane, it is appropriate to irradiate the separation membrane with energy less than 2.50 J / mm. Here, the preferred energy level of the laser having a wavelength of 980 nm can be 1.25 J / mm or more and less than 2.50 J / mm, or can be 1.25 J / mm or more and 2.49 J / mm or less. Here, the above-described energy level may be a value based on when the output of the laser is 25%.

[0074] Hereinafter, an experiment on an adhesive that can be used for the adhesive layer of the electrode assembly of this example will be described.

[0075] [Experimental Example 1] A mixture is prepared by dissolving 50 parts by weight of an adhesive polymer and 0.1 part by weight of a laser marking additive (laser marking substance) in 200 parts by weight of an organic solvent. After sufficiently stirring the mixture using a mechanical stirrer or the like, the solvent is dried using a vacuum oven to produce an adhesive resin. Here, as the adhesive polymer, a hot melt adhesive can be used, and specifically, 3M's 3762 pellet can be used. Also, as the laser marking additive, Merck's Iriotec 8850 or Iriotec 8841 can be used, and toluene can be used as the organic solvent.

[0076] [Experimental Example 2] An adhesive resin was produced in the same manner as in Experimental Example 1, except that 0.2 parts by weight of a laser marking additive was used.

[0077] [Experimental Example 3] An adhesive resin was produced in the same manner as in Experimental Example 1, except that 0.3 parts by weight of a laser marking additive was used.

[0078] [Experimental Example 4] An adhesive resin was produced in the same manner as in Experimental Example 1, except that 0.4 parts by weight of a laser marking additive was used.

[0079] [Experimental Example 5] An adhesive resin was produced in the same manner as in Experimental Example 1, except that 0.5 parts by weight of a laser marking additive was used.

[0080] [Comparative Example 1] An adhesive resin was produced in the same manner as in Experimental Example 1, except that 0.6 parts by weight of a laser marking additive was used.

[0081] [Comparative Example 2] An adhesive resin was produced in the same manner as in Experimental Example 1, except that 0.05 parts by weight of a laser marking additive was used.

[0082] As a result of manufacturing the electrode assembly 100 using the adhesive resins produced in Experimental Examples 1 to 5 and Comparative Examples 1 and 2 as adhesives, the results in Table 2 were obtained.

[0083]

Table 2

[0084] As shown in Table 2 above, when the laser marking additive is contained in an amount of less than 0.1 part by weight, the absorption amount of the laser may be low and the activation of the adhesion performance may not appear at a desired level. Further, when the laser marking additive is contained in an amount exceeding 0.5 part by weight, there is a problem that the dispersibility decreases and the viscosity or concentration of the electrolytic solution contained in the battery cell increases due to the laser marking additive. Therefore, in the production of the electrode assembly 100 of the present embodiment, in order for the adhesive layer 140 to be formed and the effect thereof to be exhibited, it is appropriate that the laser marking additive is contained in an amount of 0.1 to 0.5 part by weight based on 50 parts by weight of the adhesive polymer.

[0085] On the other hand, the electrode assembly 100 of the present embodiment described above can be housed in a cell case together with the electrolytic solution and provided as a battery cell.

[0086] A battery cell according to an embodiment of the present invention may include an electrode assembly 100 in which a plurality of electrodes and a plurality of separator membranes are alternately laminated, an electrode lead connected to an electrode tab extending from the plurality of electrodes, and a cell case that seals the electrode assembly with one end of the electrode lead protruding.

[0087] Also, on the one hand, the above-described battery cells can be laminated in one direction to form a battery cell laminate, and can be modularized into a battery module, and a battery management system (Battery Management System; BMS) for managing the temperature, voltage, etc. of the battery and / or A battery pack can be formed together with a cooling device or the like. The battery pack can be applied to various devices. For example, the device to which the battery pack is applied can be a means of transportation such as an electric bicycle, an electric vehicle, or a hybrid vehicle. However, the above-described devices are not limited thereto, and the battery pack according to the present embodiment can be used for various devices other than the above-described examples, and this also belongs to the scope of the present invention.

[0088] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also belong to the scope of the present invention.

Explanation of Reference Numerals

[0089] 100 Electrode assembly 101 Cell laminate 110 Positive electrode 120 Negative electrode 130 Separator 140 Adhesive layer 150 Finishing separator

Claims

1. A cell laminate in which electrodes and separation membranes are alternately laminated, An adhesive layer formed on a side surface of the cell laminate, and Including a finishing separation membrane that wraps around the cell laminate on which the adhesive layer is formed, The adhesive layer includes a laser-absorbing adhesive, The laser-absorbing adhesive includes a laser marking substance that reacts to a laser, The laser marking substance is an electrode assembly capable of absorbing the energy of the laser transmitted through the finishing separation membrane.

2. The laser marking substance is SnO ２ The electrode assembly according to claim 1, comprising a SnO (tin oxide)-based substance.

3. The laser marking substance is the SnO ２ The electrode assembly according to claim 2, further comprising a doping substance of Sb (antimony) and / or In (indium) doped into the (tin oxide) - based substance.

4. The electrode assembly according to claim 1, wherein an average particle size value of the laser marking substance corresponds to a wavelength value of the laser.

5. The electrode assembly according to claim 1, wherein the adhesive layer is formed on a side surface of the cell laminate where a long side of the separation membrane is located.

6. The electrode assembly according to claim 1, wherein the separation membrane has a zigzag shape formed by folding a rectangular sheet.

7. Forming a cell laminate in which electrodes and separation membranes are alternately laminated, Applying an adhesive to a side surface of the cell laminate, A step in which a finishing separation membrane wraps around the cell laminate to which the adhesive has been applied, Irradiating a laser to the outside of the finishing separation membrane and Including a step in which the adhesive layer is formed by curing the adhesive with the laser, The adhesive includes a laser marking substance that reacts to a laser, A method for manufacturing an electrode assembly, wherein the laser marking substance is capable of absorbing the energy of the laser transmitted through the finishing separation membrane.

8. The method for manufacturing an electrode assembly according to claim 7, wherein the wavelength value of the laser is selected according to the characteristics of the finishing separation membrane.

9. The method for manufacturing an electrode assembly according to claim 7 or 8, wherein the cell laminate includes a separation membrane having a zigzag shape.

10. A battery cell including the electrode assembly according to any one of claims 1 to 6.

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