Unit cell and battery cell including the same

Abstract

A unit cell according to one embodiment of the present invention includes a predetermined number of alternately stacked separators and electrodes; a first adhesive portion between the separator and the electrode and made of a first adhesive composition; and a second adhesive portion between the separator and another separator and made of a second adhesive composition, wherein the dispersity of the first adhesive composition is greater than the dispersity of the second adhesive composition.

Description

[Technical Field]

[0001] Cross-reference to related application(s) This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0066460 filed May 24, 2021, and Korean Patent Application No. 10-2022-0048386 filed April 19, 2022, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a unit cell and a battery cell including the same, and more particularly to a unit cell in which electrodes and separators are bonded to each other using an adhesive composition instead of conventional lamination using heat and pressure, and a battery cell including the same. [Background technology]

[0003] With technological development and increasing demand for mobile devices, the demand for secondary batteries as an energy source is rapidly increasing. In particular, secondary batteries are attracting great attention as an energy source for mobile devices such as mobile phones, digital cameras, laptops, and wearable devices, as well as for power devices such as electric bicycles, electric vehicles, and hybrid electric vehicles.

[0004] These secondary batteries are classified into cylindrical and prismatic batteries, in which the electrode assembly is housed in a cylindrical or prismatic metal can, and pouch-type batteries, in which the electrode assembly is housed in a pouch-type case made of an aluminum laminate sheet, depending on the shape of the battery case. The electrode assembly housed in the battery case is a power-generating element that can be charged and discharged and includes a positive electrode, a negative electrode, and a separator membrane interposed between the positive and negative electrodes. The electrode assembly is classified into a jelly-roll type, in which a long sheet-like positive electrode and negative electrode coated with an active material are wound with a separator membrane between them, and a stack type, in which multiple positive electrodes and negative electrodes are stacked in sequence with a separator membrane between them.

[0005] Among these, pouch-type batteries, which have a structure in which a stack-type or stack / folding-type electrode assembly is housed in a pouch-type battery case made of an aluminum laminate sheet, are increasingly being used due to their low manufacturing cost, small weight, and easy shape modification.

[0006] Here, in the case of a stacked electrode assembly, a method of manufacturing a stacked electrode assembly is generally employed in which a unit cell is first fabricated and then a plurality of the unit cells are stacked together. More specifically, the unit cells are stacked alternately in the order of separator-anode-separator-cathode, and heat and pressure are applied to the stacked unit cells using a laminating device, thereby fixing the individual components to each other.

[0007] However, after the separator-anode-separator-cathode layers are alternately stacked in this order, before entering the laminating device or during lamination, some of the separators or electrodes may be pushed out of their correct positions, resulting in problems such as breakage or differences in adhesive strength.

[0008] Therefore, it is necessary to develop a unit cell in which movement between the electrodes and the separator is prevented, and deformation and damage of the electrodes and the separator can be prevented. Summary of the Invention [Problem to be solved by the invention]

[0009] The object of the present invention is to provide a unit cell in which electrodes and separators are bonded to each other using an adhesive composition instead of the conventional lamination using heat and pressure, and a battery cell including the unit cell.

[0010] The problems to be solved by the present invention are not limited to the problems described above, and problems not mentioned will be clearly understood by those skilled in the art to which the present invention pertains from this specification and the accompanying drawings. [Means for solving the problem]

[0011] A unit cell according to one embodiment of the present invention includes a predetermined number of alternately stacked separators and electrodes; a first adhesive portion between the separator and the electrode and made of a first adhesive composition; and a second adhesive portion between the separator and another separator and made of a second adhesive composition, wherein the dispersity of the first adhesive composition is greater than the dispersity of the second adhesive composition.

[0012] The first adhesive composition may be made of at least one of an ethylene vinyl acetate (EVA)-based material, an acrylic material, and an epoxy material, and the second adhesive composition may be made of at least one of an ethylene vinyl acetate (EVA)-based material, an acrylic material, an epoxy material, a polyolefin-based material, a rubber-based material, a polyamide-based material, and a polyurethane-based material.

[0013] The second adhesive composition may be made of at least one of a polyolefin-based material, a rubber-based material, a polyamide-based material, and a polyurethane-based material.

[0014] The separator may include a lower separator and an upper separator, and the electrode may include a first electrode and a second electrode, stacked in the order of the lower separator, the first electrode, the upper separator, and the second electrode.

[0015] The first adhesive portion may be located at least one of between the first electrode and the lower separator, between the first electrode and the upper separator, and between the second electrode and the upper separator.

[0016] The second adhesive portion may be located between the upper separation film and the lower separation film.

[0017] The first adhesive portion and the second adhesive portion may each be formed in a pattern including a plurality of dots.

[0018] The dots may be spaced apart from one another.

[0019] In another embodiment of the present invention, the electrode assembly is formed by alternately stacking the unit cells, and the first adhesive portion includes an adhesive pattern disposed at the same position between each of the electrodes and the separator.

[0020] According to another embodiment of the present invention, an electrode assembly is formed by alternately stacking the unit cells, and the first adhesive portion includes adhesive patterns that are staggered between the electrodes and the separators.

[0021] A battery cell according to another embodiment of the present invention includes an electrode assembly in which the unit cells are alternately stacked, and an electrolyte.

[0022] The first adhesive portion may be dissolved in the electrolyte solution.

[0023] The first adhesive composition may be made of at least one of an ethylene vinyl acetate (EVA)-based material, an acrylic material, and an epoxy material, and the second adhesive composition may be made of at least one of an ethylene vinyl acetate (EVA)-based material, an acrylic material, an epoxy material, a polyolefin-based material, a rubber-based material, a polyamide-based material, and a polyurethane-based material.

[0024] The content of the first adhesive composition and the second adhesive composition may be 0.8 wt % or more and 1.2 wt % or less with respect to the content of the electrolyte solution.

[0025] The content of the first adhesive composition may be 0.6 wt% to 0.9 wt% of the content of the electrolyte solution, and the content of the second adhesive composition may be 0.1 wt% to 0.45 wt% of the content of the electrolyte solution.

[0026] The second adhesive composition may be made of at least one of a rubber-based material, a polyamide-based material, and a polyurethane-based material.

[0027] The content of the second adhesive composition may be 0.1 wt % to 0.2 wt % of the content of the electrolyte solution.

[0028] The electrolyte may be at least one of an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel polymer electrolyte, a solid inorganic electrolyte, and a molten inorganic electrolyte.

[0029] The battery cell may have a zigzag shape due to the separator being folded.

[0030] According to another embodiment of the present invention, a method for manufacturing a unit cell includes applying a first adhesive to at least one of a first surface of an electrode or a bonding region of a first separator; applying the first adhesive to at least one of a second surface of the electrode or a bonding region of a second separator, the second surface of the electrode being located on the opposite side of the electrode from the first surface of the electrode; applying a second adhesive to at least one of a peripheral region of the first separator or a peripheral region of the second separator; and stacking the electrode between the first separator and the second separator so that the first surface of the electrode contacts the bonding region of the first separator and the second surface of the electrode contacts the bonding region of the second separator, thereby forming at least a portion of an electrode assembly, wherein the electrode assembly is formed such that the peripheral regions of the first and second separators extend outward beyond the periphery of the electrode, and the peripheral regions of the first and second separators face each other without an electrode therebetween, and the dispersibility of the first adhesive in an electrolyte is greater than the dispersibility of the second adhesive in the electrolyte.

[0031] The dispersibility of the first adhesive in the electrolyte may be greater than the dispersibility of the second adhesive in the electrolyte.

[0032] The peripheral regions of the first and second separators may extend around the periphery of each of the first and second separators, and each of the peripheral regions may surround a joining region of each of the first and second separators.

[0033] The first adhesive may be made of at least one of an ethylene-vinyl acetate (EVA)-based material, an acrylic-based material, and an epoxy-based material, and the second adhesive may be made of at least one of an ethylene-vinyl acetate (EVA)-based material, an acrylic-based material, an epoxy-based material, a polyolefin-based material, a rubber-based material, a polyamide-based material, and a polyurethane-based material.

[0034] The first adhesive and the second adhesive may each be applied in a respective spaced apart dot pattern.

[0035] In the dot pattern of the first adhesive, the dots may be arranged in a grid of rows and columns.

[0036] A method for manufacturing a battery cell according to another embodiment of the present invention includes alternately stacking the unit cells to form an electrode assembly; and disposing the electrode assembly and an electrolyte in a battery case.

[0037] The method for manufacturing a battery cell may further include dissolving at least a portion of the first adhesive in the electrolyte solution.

[0038] The electrolyte may be at least one of an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel polymer electrolyte, a solid inorganic electrolyte, and a molten inorganic electrolyte.

[0039] The total content of the first adhesive may be 0.6 wt % or more and 0.9 wt % or less with respect to the total content of the electrolyte solution.

[0040] The total content of the second adhesive may be 0.1 wt % or more and 0.45 wt % or less with respect to the total content of the electrolyte solution.

[0041] The total content of the first adhesive and the second adhesive in the battery case may be 0.8 wt % or more and 1.2 wt % or less of the total content of the electrolyte in the battery case.

[0042] The total content of the first adhesive in the battery case may be 0.6 wt% or more and 0.9 wt% or less of the total content of the electrolyte in the battery case, and the total content of the second adhesive in the battery case may be 0.1 wt% or more and 0.45 wt% or less of the total content of the electrolyte in the battery case.

[0043] The second adhesive may be made of at least one of a polyolefin-based material, a rubber-based material, a polyamide-based material, and a polyurethane-based material.

[0044] The total content of the second adhesive in the battery case may be 0.1 wt % to 0.2 wt % of the total content of the electrolyte in the battery case. [Effects of the Invention]

[0045] According to an embodiment, the unit cell of the present invention and a battery cell including the same may adhere the electrodes and separators and the separators to each other using an adhesive composition instead of the conventional lamination using heat and pressure, thereby preventing movement between the electrodes and the separators and preventing deformation and damage of the electrodes and the separators.

[0046] The effects of the present invention are not limited to the effects described above, and effects not mentioned will be clearly understood by those skilled in the art to which the present invention pertains from this specification and the accompanying drawings. [Brief explanation of the drawings]

[0047] [Figure 1] FIG. 2 is an exploded perspective view of a unit cell according to an embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view showing a unit cell in which the components of FIG. 1 are combined. [Figure 3] FIG. 3 is a cross-sectional view taken along the AA axis of FIG. 2. [Figure 4] FIG. 10 is a top view of a battery cell according to another embodiment of the present invention. [Figure 5] 3 is a graph showing the results of dispersion depending on the content of the adhesive composition contained in the unit cell of FIG. 2. [Figure 6] 3 is a graph showing LSV (Linear Sweep Voltammetry) of the adhesive composition contained in the unit cell of FIG. 2. [Figure 7] FIG. 4 is a cross-sectional view showing an electrode assembly according to another embodiment of the present invention. [Figure 8] FIG. 4 is a cross-sectional view showing an electrode assembly according to still another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0048] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention may be embodied in various different forms and is not limited to the embodiments set forth herein.

[0049] In order to clearly explain the present invention, parts unnecessary for the explanation are omitted, and the same reference numerals are used throughout the specification to refer to the same or similar components.

[0050] Furthermore, the size and thickness of each component shown in the drawings are arbitrarily shown for the convenience of explanation, and the present invention is not necessarily limited to those shown in the drawings. In the drawings, thicknesses are exaggerated to clearly show multiple layers and regions. In the drawings, thicknesses of some layers and regions are exaggerated for the convenience of explanation.

[0051] Furthermore, throughout the specification, when a part is said to "comprise" a certain element, this does not mean that it excludes other elements and may further include other elements, unless specifically stated to the contrary.

[0052] Also, throughout the specification, "on a plane" means when the subject part is viewed from above, and "on a cross section" means when the subject part is cut vertically and viewed from the side.

[0053] Hereinafter, a unit cell according to an embodiment of the present invention will be described.

[0054] Fig. 1 is an exploded perspective view of a unit cell according to an embodiment of the present invention. Fig. 2 is a perspective view showing a unit cell in which the components of Fig. 1 are combined. Fig. 3 is a cross-sectional view taken along the AA axis of Fig. 2.

[0055] 1 and 2, a unit cell according to an embodiment of the present invention includes a predetermined number of alternately stacked separators 210, 250 and electrodes 110, 150; a first adhesive portion 310 positioned between the separators 210, 250 and the electrodes 110, 150 and made of a first adhesive composition; and a second adhesive portion 350 positioned between the separators 210, 250 and other separators 210, 250 and made of a second adhesive composition.

[0056] More specifically, the separators 210, 250 include a lower separator 210 and an upper separator 250, and the electrodes 110, 150 include a first electrode 110 and a second electrode 150, and the lower separator 210, the first electrode 110, the upper separator 250, and the second electrode 150 may be stacked in this order.

[0057] Here, the first electrode 110 may include a first electrode tab 115 protruding in one direction, and the second electrode 150 may include a second electrode tab 155 protruding in one direction. For example, as shown in Figures 1 and 2, the first electrode 110 and the second electrode 150 may be stacked such that the upper separator 250 is located between them, and the first electrode tab 115 of the first electrode 110 and the second electrode tab 155 of the second electrode 150 may be stacked such that they are positioned in opposite directions. However, this is not limited thereto, and a structure in which the first electrode tab 115 and the second electrode tab 155 are stacked such that they are positioned in the same direction may also be included in this embodiment.

[0058] Here, the first electrode 110 and the second electrode 150 may each include an electrode current collector and an active material layer disposed on the electrode current collector. Here, the active material layer may be composed of an electrode composition including an electrode active material. More specifically, the first electrode 110 and the second electrode 150 may be a positive electrode or a negative electrode. Here, the positive electrode may include a positive electrode current collector and an active material layer including a positive electrode active material, and the negative electrode may include a negative electrode current collector and an active material layer including a negative electrode active material. For example, the first electrode 110 may be a negative electrode and the second electrode 150 may be a positive electrode. However, this is not limited thereto, and the opposite case may also be included in this embodiment.

[0059] The negative electrode active material may be a common negative electrode active material for lithium secondary batteries in the art, such as lithium metal, lithium alloy, petroleum coke, activated carbon, graphite, silicon, tin, metal oxides, or other carbons.

[0060] In addition, the positive electrode active material may be, for example, selected from the group consisting of lithium-cobalt-based oxides, lithium-manganese-based oxides, lithium-nickel-manganese-based oxides, lithium-manganese-cobalt-based oxides, lithium-nickel-manganese-cobalt-based oxides, and lithium iron phosphate, or may be a combination thereof or a composite oxide thereof.

[0061] The negative electrode current collector or the positive electrode current collector is not particularly limited as long as it does not induce chemical changes in the battery and has high conductivity. For example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. may be used.

[0062] The separators 210 and 250 separate the first electrode 110 and the second electrode 150 and provide a path for lithium ions to move. The separators 210 and 250 include a lower separator 210 and an upper separator 250, and the lower separator 210 and the upper separator 250 may be made of different or the same material.

[0063] For example, any separator typically used in lithium secondary batteries may be used for the separators 210 and 250. A separator having low resistance to ion migration and excellent electrolyte humidification is particularly preferred. Specifically, a porous polymer film, such as a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, or an ethylene / methacrylate copolymer, or a laminate structure of two or more layers thereof, may be used.

[0064] Hereinafter, the first adhesive part 310 and the second adhesive part 350 included in the unit cell according to this embodiment will be mainly described.

[0065] Referring to Figures 1 and 3, the first adhesive portion 310 may be located at least one of between the first electrode 110 and the lower separator 210, between the first electrode 110 and the upper separator 250, and between the second electrode 150 and the upper separator 250.

[0066] As a result, the first adhesive part 310 can fix the first electrode 110 and the second electrode 150 to the lower separation membrane 210 and / or the upper separation membrane 250, respectively. In other words, the first adhesive part 310 can prevent movement between the electrodes 110, 150 and the separation membranes 210, 250, and can prevent deformation and damage of the electrodes 110, 150 and the separation membranes 210, 250.

[0067] The second adhesive portion 350 may be located between the upper separation membrane 250 and the lower separation membrane 210. More specifically, the second adhesive portion 350 may be located between an end of the lower separation membrane 210 and an end of the first electrode 110. The second adhesive portion 350 may be located between an end of the upper separation membrane 250 and an end of the first electrode 110. In other words, the second adhesive portion 350 is located on a surface of the separation membranes 210 and 250 that does not contact the first electrode 110, but the second adhesive portion 350 may be located along the periphery of the first electrode 110. Here, the second adhesive portion 350 may also be selectively located in a portion where the electrode tabs 115 and 155 protruding from the electrodes 110 and 150 are located.

[0068] As a result, the first electrode 110 is positioned between the upper separation film 210 and the lower separation film 250, and because the upper separation film 210 and the lower separation film 250 can be fixed to each other by the second adhesive part 350, the first electrode 110 can be prevented from moving between the upper separation film 210 and the lower separation film 250. In other words, the second adhesive part 350 fixes the upper separation film 210 and the lower separation film 250 to each other along the periphery of the first electrode 110, thereby limiting the space in which the first electrode 110 can move, and thereby preventing deformation and damage of the first electrode 110.

[0069] 1 and 3, the first adhesive portion 310 and the second adhesive portion 350 may each be formed in a pattern including a plurality of dots. More specifically, the dots may be spaced apart from one another. Here, the spacing between the dots may be adjusted to be the same or different as needed.

[0070] As a result, the first adhesive portion 310 and the second adhesive portion 350 can be formed in the above-described pattern, which advantageously allows the electrode assembly 1100 (FIG. 4) including a plurality of unit cells 100 to be rapidly impregnated with electrolyte when the electrolyte is poured into the electrode assembly 1100 (FIG. 4). More specifically, the first adhesive portion 310 and the second adhesive portion 350 have a plurality of dots spaced apart from one another, which advantageously allows the electrolyte to flow between the dots. In other words, according to this embodiment, the manufacturing time for the battery cell 100 (FIG. 4) can be relatively shortened and the yield can be improved.

[0071] Furthermore, the first adhesive part 310 may be made of a first adhesive composition, and the second adhesive part 350 may be made of a second adhesive composition. More specifically, the first adhesive part 310 may obstruct the lithium ion passage between the electrodes 110, 150 and the separators 210, 250. That is, the first adhesive part 310 is preferably made of a material that has a relatively high dispersibility or high solubility in the electrolyte. Here, the dispersibility of the first adhesive composition contained in the first adhesive part 310 may be the same as or greater than the dispersibility of the second adhesive composition contained in the second adhesive part 350.

[0072] According to one embodiment, the first adhesive composition included in the first adhesive portion 310 and the second adhesive composition included in the second adhesive portion 350 may include materials having the same composition. For example, the first adhesive composition may be made of at least one of an ethylene vinyl acetate (EVA)-based material, an acrylic material, and an epoxy-based material, and the second adhesive composition may be made of at least one of an ethylene vinyl acetate (EVA)-based material, an acrylic material, an epoxy-based material, a polyolefin-based material, a rubber-based material, a polyamide-based material, and a polyurethane-based material.

[0073] According to another embodiment, the first adhesive portion 310 and the second adhesive portion 350 may include materials with different compositions. More specifically, the first adhesive composition and the second adhesive composition may have different dispersibilities. In other words, the dispersibilities of the first adhesive composition may be greater than those of the second adhesive composition. For example, the first adhesive composition may be made of at least one of an ethylene vinyl acetate (EVA)-based material, an acrylic-based material, and an epoxy-based material, and the second adhesive composition may be made of at least one of a polyolefin-based material, a rubber-based material, a polyamide-based material, and a polyurethane-based material. For example, if the first adhesive composition is made of an acrylic-based material, the acrylic-based material may have a certain degree of solubility in the electrolyte because it contains an ester group.

[0074] As a result, the first adhesive composition contained in the first adhesive portion 310 may have a relatively similar or higher dispersity than the second adhesive composition contained in the second adhesive portion 350. Therefore, when an electrolyte solution is poured into an electrode assembly 1100 (FIG. 4) including a plurality of unit cells 100, the first adhesive composition may dissolve between the electrodes 110, 150 and the separators 210, 250. In other words, in this case, the first adhesive portion 310 located between the electrodes 110, 150 and the separators 210, 250 may dissolve in the electrolyte solution and not block the lithium ion passage between the electrodes 110, 150 and the separators 210, 250.

[0075] Referring to FIG. 6, unlike the first adhesive composition included in the first adhesive portion 310 corresponding to position 1, the second adhesive composition included in the second adhesive portion 350 corresponding to position 2 exhibits an oxidation reaction at around 4.0 V as determined by linear sweep voltammetry (LSV). This can lead to side reactions within the battery cell, shortening its capacity and lifespan. Therefore, it is not recommended to use the second adhesive composition in the first adhesive portion 310. One reason for forming the second adhesive portion 350 is to prevent the separator from breaking during the electrolyte injection process. The results shown in FIG. 6 can be obtained when the first adhesive composition is made of at least one of an ethylene-vinyl acetate-based material, an acrylic-based material, and an epoxy-based material, and the second adhesive composition is made of at least one of a polyolefin-based material, a rubber-based material, a polyamide-based material, and a polyurethane-based material.

[0076] The separator according to the embodiments described herein may be a ceramic coated separator (CCS). Generally, a separator has a substrate film and a coating layer formed on at least one side of the substrate film. The coating layer may contain alumina powder and a binder that holds the powder together. While a safety reinforced separator (SRS) has a large amount of binder coated on the surface of the coating layer, a CCS may not have a binder coated on the surface of the coating layer or may have a much lower binder content than an SRS. For example, in the case of a CCS separator according to the present embodiment, the binder content coated on the surface of the coating layer of the separator may be approximately 3 wt% or less.

[0077] When the separator is CCS, the internal electrodes included in the electrode assembly are transported in an unfixed state, which can lead to misalignment during transport. While the separator can be fixed using heat and pressure when the electrode and separator stack is formed, the internal electrodes can also become misaligned during transport to a heat and pressure fixing device. Another drawback is that attaching the electrodes and separator using heat and pressure requires the use of expensive separators with high binder content. In contrast, this embodiment can increase the fixing strength while preventing misalignment of the internal electrodes during transport.

[0078] FIG. 4 is a top view of a battery cell according to another embodiment of the present invention.

[0079] 2 and 4, a battery cell 1000 according to another embodiment of the present invention includes an electrode assembly 1100 in which the above-described unit cells 100 are alternately stacked, and an electrolyte. Here, first electrode tabs 1150 in which the first electrode tabs 115 of the unit cells 100 are stacked, and second electrode tabs 1550 in which the second electrode tabs 155 of the unit cells 100 are stacked may be electrically connected to electrode leads 3000, respectively. Lead films 4000 may be located on the top and / or bottom of the electrode leads 3000.

[0080] The electrode assembly 1100 is installed inside the battery case 120, and the electrode assembly 1100 may be located in a recessed receiving portion 2100 together with the electrolyte. The sealing portion 2500 may be formed by sealing the outer peripheries of the battery case 2000 together by heat sealing.

[0081] For example, the electrolyte may be at least one of an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel polymer electrolyte, a solid inorganic electrolyte, and a molten inorganic electrolyte, but is not limited thereto and may include any commonly used electrolyte.

[0082] According to this embodiment, the first adhesive portion 310 may be dissolved in the electrolyte solution. More specifically, the first adhesive composition contained in the first adhesive portion 310 may be dissolved in the electrolyte solution. More preferably, the first adhesive composition contained in the first adhesive portion 310 may be completely dissolved in the electrolyte solution.

[0083] Therefore, in this embodiment, the first adhesive part 310 is dissolved in the electrolyte solution and does not obstruct the lithium ion passage between the electrodes 110, 150 and the separators 210, 250, thereby improving the battery performance of the battery cell.

[0084] The content of the first adhesive composition and the second adhesive composition may be 0.8 wt% or more and 1.2 wt% or less with respect to the content of the electrolyte solution. More specifically, the content of the first adhesive composition and the second adhesive composition may be 0.85 wt% or more and 1.15 wt% or less with respect to the content of the electrolyte solution. The content of the first adhesive composition and the second adhesive composition may be 0.9 wt% or more and 1.1 wt% or less with respect to the content of the electrolyte solution.

[0085] Therefore, in the battery cell 1000 according to the present embodiment, the first adhesive composition and the second adhesive composition are contained in the ratio within the above-mentioned range, so that the first adhesive portion 310 located between the electrodes 110, 150 and the separators 210, 250 can be easily dispersed and dissolved in the electrolyte, and thus the lithium ion passage between the electrodes 110, 150 and the separators 210, 250 can be unobstructed.

[0086] On the other hand, if the content of the first adhesive composition and the second adhesive composition is less than 0.8 wt % relative to the content of the electrolyte solution, the adhesive strength between the electrodes 110, 150 and the separators 210, 250 or between the lower separator 210 and the upper separator 250 due to the first adhesive portion 310 and the second adhesive portion 350 may be excessively reduced. Also, if the content of the first adhesive composition and the second adhesive composition is more than 1.2 wt % relative to the content of the electrolyte solution, the first adhesive portion 310 located between the electrodes 110, 150 and the separators 210, 250 may not be easily dispersed or dissolved in the electrolyte solution, which may block the lithium ion pathway and result in uncharged regions.

[0087] The content of the first adhesive composition may be 0.6 wt% to 0.9 wt% and the content of the second adhesive composition may be 0.1 wt% to 0.45 wt%. More specifically, the content of the first adhesive composition may be 0.65 wt% to 0.85 wt% and the content of the second adhesive composition may be 0.15 wt% to 0.4 wt%. For example, the content of the first adhesive composition may be 0.7 wt% to 0.8 wt% and the content of the second adhesive composition may be 0.15 wt% to 0.35 wt%.

[0088] Therefore, in the battery cell 1000 according to the present embodiment, the first adhesive composition and the second adhesive composition are contained in the ratios within the above-mentioned ranges, so that the electrodes 110, 150 and the separators 210, 250 are fixed to prevent the electrodes from shifting, and the first adhesive portion 310 and the second adhesive portion 350 can be easily dispersed and dissolved in the electrolyte.

[0089] On the other hand, if the content of the first adhesive composition is less than 0.6 wt% or more than 0.9 wt%, the adhesive strength between the first adhesive portion 310 and the electrode may be insufficient, resulting in electrode misalignment, or the first adhesive portion 310 may not be easily dispersed or dissolved in the electrolyte, obstructing the lithium ion pathway and resulting in uncharged regions.

[0090] Furthermore, if the content of the second adhesive composition is less than 0.1 wt% or more than 0.45 wt%, the adhesive strength between the lower separation membrane 210 and the upper separation membrane 250 may be excessively reduced, or the content of the adhesive composition in the second adhesive portion 350 may be too high, resulting in the second adhesive portion 350 exceeding the surface area that can be formed.

[0091] Furthermore, when the second adhesive composition is made of at least one of a rubber-based material, a polyamide-based material, and a polyurethane-based material that has low dispersibility in the electrolyte, the content of the second adhesive composition may be 0.1 wt% to 0.2 wt% of the electrolyte. More specifically, in this case, the content of the second adhesive composition may be 0.12 wt% to 0.18 wt% of the electrolyte. For example, in this case, the content of the second adhesive composition may be 0.14 wt% to 0.16 wt% of the electrolyte.

[0092] Therefore, in the battery cell 1000 according to this embodiment, even if the dispersibility of the second adhesive composition is relatively very small, the second adhesive composition is contained in the content range described above, so that the electrodes 110, 150 and the separators 210, 250 are fixed to each other to prevent the electrodes from shifting, and the first adhesive portion 310 and the second adhesive portion 350 can be easily dispersed and dissolved in the electrolyte.

[0093] On the other hand, if the content of the second adhesive composition is less than 0.1 wt% or more than 0.2 wt%, the adhesive strength between the lower separator 210 and the upper separator 250 may be excessively reduced, or the content of the adhesive composition in the second adhesive portion 350 may be too high, resulting in a decrease in dispersion.

[0094] The present invention will be described below with more specific examples. However, the following examples are for illustrative purposes only and the scope of the present invention is not limited thereto.

[0095] <Experimental Example 1 - Measurement of Dispersion Degree> Using an electrolyte solution in which 1M LiPF6 lithium salt was mixed at a ratio of EC:EMC = 3:7 as a standard, the dispersion of adhesive compositions such as ethylene vinyl acetate (EVA)-based materials, acrylic-based materials, epoxy-based materials, polyolefin-based materials, rubber-based materials, polyamide-based materials, and polyurethane-based materials was measured.

[0096] The acrylic material was BASF's acResin 250UV, the EVA material was Henkel's Technomelt 4046, the epoxy material was Henkel's Lotite EA608, the polyolefin material was Henkel's Supra 502, the rubber material was Henkel's 2802 dispomelt, the polyamide material was Henkel's HPX 002, and the polyurethane material was Fuller's EH9702. Figure 5 shows the dispersion results for Technomelt 4046. The adhesive composition content was increased from left to right, and the dispersion was measured according to the content. As shown on the far right of Figure 5, the adhesive composition was suspended at 1 wt%, which is indicated by NG. The same experiment was also conducted on other materials, and the results are shown in Table 1.

[0097] [Table 1]

[0098] Example 1 LiNi as the positive electrode active material 0.6 Mn 0.2 Co 0.2 O2, carbon black as a conductive agent, and polyvinylidene fluoride (PVdF) as a binder were used, and the weight ratio of the positive electrode active material:conductive agent:binder was 96:2:2. The solvent NMP was added to the mixture to prepare a positive electrode active material slurry. The positive electrode active material slurry was applied to an aluminum current collector, which was then dried and rolled to prepare a positive electrode.

[0099] Artificial graphite was used as the negative active material, carbon black as the conductive agent, and an SBR emulsion aqueous solution as the binder. The weight ratio of the negative active material:conductive agent:binder was 94:1:5, and water was added to the mixture to prepare a negative active material slurry. The negative active material slurry was applied to a copper current collector, which was then dried and rolled to prepare a negative electrode.

[0100] A slurry of Al2O3 and PVDF mixed at a weight ratio of 94:6 was applied to both sides of a polyethylene / polypropylene base sheet (thickness: 10 μm) (thickness: 3 μm on each side) and dried at 60°C to fabricate a separator. The separators are named upper and lower separators depending on their positions.

[0101] The electrolyte was prepared by adding 1M LiPF6 lithium salt to a solution mixed in a ratio of EC:EMC=3:7.

[0102] The manufactured unit cell was fabricated by alternately stacking the manufactured lower separator, anode, upper separator, and cathode in this order, with a first adhesive layer made of acResin 250UV at a content of 0.75 wt% of the electrolyte between the separator and the anode and between the separator and the cathode, and a second adhesive layer made of acResin 250UV at a content of 0.25 wt% of the electrolyte between the upper separator and the lower separator.

[0103] <Example 2> In Example 1, a composition consisting of Lotite EA608 was used for the first adhesive portion. Except for this, a unit cell was manufactured in the same manner as in Example 1.

[0104] Example 3 In Example 1, the first adhesive part was made of a composition consisting of Technomelt 4046. Except for this, a unit cell was manufactured in the same manner as in Example 1.

[0105] Example 4 In Example 1, the second adhesive layer was made of a composition containing Supra 502. Except for this, a unit cell was manufactured in the same manner as in Example 1.

[0106] <Example 5> In Example 1, a composition made of Lotite EA608 was used for the first adhesive part, and a composition made of Supra 502 was used for the second adhesive part. Except for this, a unit cell was manufactured in the same manner as in Example 1.

[0107] Example 6 In Example 1, the first adhesive layer was made of a composition containing Technomelt 4046, and the second adhesive layer was made of a composition containing Supra 502. Except for this, a unit cell was manufactured in the same manner as in Example 1.

[0108] Example 7 In Example 1, the second adhesive was made of a composition containing 2802dispomelt at a content of 0.15 wt% relative to the content of the electrolyte. Except for this, a unit cell was manufactured in the same manner as in Example 1.

[0109] <Comparative Example 1> In Example 1, the first adhesive portion contained 0.25 wt% of the electrolyte solution, and the second adhesive portion contained 0.75 wt% of the electrolyte solution. Except for this, a unit cell was manufactured in the same manner as in Example 1.

[0110] <Comparative Example 2> In Example 1, the first adhesive portion contained 0.5 wt% of the electrolyte solution, and the second adhesive portion contained 0.25 wt% of the electrolyte solution. Except for this, a unit cell was manufactured in the same manner as in Example 1.

[0111] <Comparative Example 3> In Example 1, the second adhesive portion was made of a composition having a content of 0.5 wt % relative to the content of the electrolyte solution, except for this, a unit cell was manufactured in the same manner as in Example 1.

[0112] <Comparative Example 4> In Example 1, a composition made of Supra 502 was used for the first adhesive part, and a composition made of Supra 502 was used for the second adhesive part. Except for this, a unit cell was manufactured in the same manner as in Example 1.

[0113] <Comparative Example 5> In Example 1, the first adhesive part was made of a composition containing Supra 502. Except for this, a unit cell was manufactured in the same manner as in Example 1.

[0114] <Experimental Example 2 (Measurement of Dispersity, Viscosity, and Ion Conductivity)> For the prepared Examples 1 to 7 and Comparative Examples 1 to 5, the dispersibility, viscosity, and ionic conductivity were measured according to the content of the adhesive composition contained in the first adhesive part and the second adhesive part relative to the content of the electrolyte solution.

[0115] The degree of dispersion was measured in the same manner as in Experimental Example 1, and the results are shown in Table 2.

[0116] The ionic conductivity was measured using an ionic conductivity measurement device using Mettler Toledo's cond probe inlab710 equipment.

[0117] The viscosity can be measured at 10 rpm by replacing the spindle part of a Brookfield DV2T LV TJ10 model with a cone and a plate and applying a CPA-40Z cone.

[0118] Here, the viscosity and ionic conductivity were judged to be suitable if they were within ±10% of the standard of an electrolyte solution in which 1M LiPF6 lithium salt was mixed at an EC:EMC ratio of 3:7 (viscosity: 3.78 cPs (at 25°C) and ionic conductivity: 8.65 mS / cm). The results are shown in Table 2.

[0119] [Table 2]

[0120] <Experimental Example 3 (Measurement of electrode misalignment)> For each of the unit cells manufactured in Examples 1 to 7 and Comparative Examples 1 to 5, electrode misalignment was measured at a resolution of 33 μm / pixel under conditions of 170 kV, 200 μA, and 34 W using a CT scanner from GE. The results are shown in Table 3.

[0121] [Table 3]

[0122] <Analysis of experimental results> Referring to Tables 1 to 3, when a composition containing 0.75 wt% acResin 250UV was used for the first adhesive portion and a composition containing 0.25 wt% acResin 250UV, Loctite EA608, and Technomelt 4046 was used for the second adhesive portion as in Examples 1 to 3, it was confirmed that the dispersion degree, viscosity, and ionic conductivity were all excellent and there was no electrode slippage.

[0123] In contrast, when a composition consisting of 0.75 wt% Supra502 was used in the first adhesive layer and a composition consisting of 0.25 wt% Supra502 was used in the second adhesive layer, as in Comparative Example 4, there was no electrode slippage, but the dispersity was so low that viscosity and ionic conductivity could not be measured. The same can be said for 2802dispomelt, HPX002, and EH9702, which have lower dispersity than Supra502.

[0124] Therefore, when the dispersities of the first adhesive part and the second adhesive part are the same or similar to each other, it can be confirmed that, unlike Comparative Example 4, it is suitable for the first adhesive part and the second adhesive part to be made of at least one of acResin 250UV, Loctite EA608, and Technomelt 4046, which each have a relatively high dispersity, as in Examples 1 to 3.

[0125] It was also confirmed that electrode misalignment occurred in Comparative Example 2, in which the total content of the first adhesive part and the second adhesive part was small, unlike Example 1. It was also confirmed that the degree of dispersion was too low in Comparative Example 3, in which the total content of the first adhesive part and the second adhesive part was large, unlike Example 1, and that the viscosity and ionic conductivity were not measurable.

[0126] This confirms that the total content of the first adhesive portion and the second adhesive portion is preferably in the range of 0.8 wt % to 1.2 wt %, as in Example 1.

[0127] Furthermore, unlike Example 1, it was confirmed that electrode slippage occurs when the total content of the first adhesive portion and the second adhesive portion is the same but the content of the first adhesive portion is small and the content of the second adhesive portion is large. Furthermore, it was confirmed that electrode slippage occurs in Comparative Example 2, where the content of the first adhesive portion is small, unlike Example 1. Furthermore, it was confirmed that the dispersity is too low and the viscosity and ionic conductivity cannot be measured in Comparative Example 3, where the content of the second adhesive portion is large, unlike Example 1.

[0128] This confirms that it is appropriate for the content of the first adhesive portion to be in the range of 0.6 wt% or more and 0.9 wt% or less, and for the content of the second adhesive portion to be in the range of 0.1 wt% or more and 0.45 wt% or less, as in Example 1.

[0129] Furthermore, referring to Tables 1 to 3, when a composition consisting of 0.75 wt% of acResin 250UV, Loctite EA608, and Technomelt 4046 was used in the first adhesive portion, and a composition consisting of 0.25 wt% of Supra 502 was used in the second adhesive portion, as in Examples 4 to 6, it was confirmed that the dispersion degree, viscosity, and ionic conductivity were all excellent, and there was no electrode slippage.

[0130] In contrast, when a composition consisting of 0.75 wt% Supra502 was used in the first adhesive layer and a composition consisting of 0.25 wt% acResin 250UV was used in the second adhesive layer, as in Comparative Example 5, there was no electrode slippage, but the dispersity was so low that viscosity and ionic conductivity could not be measured. The same can be said for cases where 2802dispomelt, HPX 002, or EH9702, which have lower dispersity than Supra502, are used in the first adhesive layer.

[0131] This confirms that when the difference in dispersity between the first adhesive portion and the second adhesive portion is large, unlike Comparative Example 5, it is appropriate to use, as in Examples 4 to 6, a first adhesive portion made of at least one of acResin 250UV, Loctite EA608, and Technomelt 4046, which have relatively high dispersities, and a second adhesive portion made of at least one of Supra502, 2802dispomelt, HPX 002, and EH9702, which have relatively low dispersities.

[0132] In addition, in the case of Comparative Example 3, in which the content of the first adhesive part is large, unlike Example 4, there is no electrode misalignment, but it can be confirmed that the dispersity is too low and therefore the viscosity and ionic conductivity cannot be measured. Furthermore, in the case of Comparative Example 3, in which the content of the second adhesive part is large, the dispersity is too low and therefore it can be confirmed that the viscosity and ionic conductivity cannot be measured, unlike Example 4.

[0133] This confirms that it is appropriate for the content of the first adhesive portion to be in the range of 0.6 wt% or more and 0.9 wt% or less, and for the content of the second adhesive portion to be in the range of 0.1 wt% or more and 0.45 wt% or less, as in Example 1.

[0134] Furthermore, referring to Tables 1 to 3, when a composition consisting of 0.75 wt% acResin 250UV was used for the first adhesive portion and a composition consisting of 0.15 wt% 2802dispomelt was used for the second adhesive portion as in Example 7, it was confirmed that the dispersibility, viscosity, and ionic conductivity were all excellent and there was no electrode slippage.

[0135] On the other hand, if the dispersibility of the second adhesive part is too low, it may be impossible to measure the viscosity and ionic conductivity. Therefore, in the case of 2802dispomelt, HPX002, and EH9702, in which the dispersibility of the adhesive composition contained in the second adhesive part is too low, it can be confirmed that the content of the second adhesive part should be in the range of 0.1 wt% to 0.2 wt%, as in Example 7.

[0136] FIG. 7 is a cross-sectional view showing an electrode assembly according to another embodiment of the present invention.

[0137] 7, the electrode assembly 3 according to this embodiment may include an electrode stack 40 manufactured by repeatedly forming a plurality of radical units 30. Here, the radical units 30 may be units in which the separator 322 is folded to form a zigzag pattern and covers the electrode 31, and the electrode 31 and the separator 322 are stacked together. That is, the radical units 30 may be units in which the electrode 31 and the separator 322 are stacked together, with one side and the other side of the separator 322 being folded sequentially to cover the electrode 31.

[0138] The electrode assembly 3 may be attached with a fixing tape, but instead of the fixing tape, one end of the separator 322 may surround a portion of the outer surface of the electrode stack 40. In the basic unit 30 of this embodiment, the electrodes 3112, 3122 and the separator 322 may be adhered to each other with an adhesive 34. As a result, the electrodes 3112, 3122 and the separator 322 can maintain their alignment due to the adhesive force of the adhesive 34.

[0139] In the electrode stack 40 of this embodiment, the separator 322 covers the top, bottom, and one side of the electrodes 3112 and 3122, and the stacked alignment of the radical units 30 can be maintained without the fixing tape. In addition, if the fixing tape is attached to the outside of the electrode stack 40 of this embodiment or if one end of the separator 322 is enclosed, the stacked alignment of the radical units 30 can be more stably maintained.

[0140] In addition, in the electrode assembly 3 manufactured in this embodiment, the adhesive 34 may be disposed at the same position between each of the electrodes 3112, 3122 and the separator 322. For example, as shown in Fig. 7, in the electrode assembly 3 of this embodiment, the adhesive 34 disposed between the lower part of the first electrode 3112 and the separator 322 and the adhesive 34 disposed between the upper part of the first electrode 3112 and the separator 322 may be disposed on the same vertical line based on the bottom surface of the first electrode 3112 or the separator 322, respectively, and the intervals at which the adhesives 34 are disposed may be the same. This can be similarly explained in the case of the adhesive 34 disposed between the second electrode 3122 and the separator 322.

[0141] As a result, in the electrode assembly 3 manufactured in this embodiment, the adhesive 34 is disposed at the same position between each of the electrodes 3112, 3122 and the separator 322, which has the advantage of increasing process time and efficiency.

[0142] FIG. 8 is a cross-sectional view showing an electrode assembly according to still another embodiment of the present invention.

[0143] 8, in the electrode assembly 4 according to this embodiment, the adhesives 34 may be disposed between the electrodes 3112, 3122 and the separator 322, and the adhesives 34 disposed in adjacent layers may be staggered. For example, as shown in FIG. 8, in the electrode assembly 4 according to this embodiment, the first adhesive 34-1 disposed between the lower part of the first electrode 3112 and the separator 322 and the second adhesive 34-2 disposed between the upper part of the first electrode 3112 and the separator 322 may be staggered from each other. In this case, the first adhesive 34-1 and the second adhesive 34-2 may only be staggered from each other, and the spacing between them may be the same. This can be similarly explained for the adhesive 14 disposed between the second electrode 3122 and the separator 322.

[0144] However, the present invention is not limited thereto, and the structure in which the first adhesive 34-1 and the second adhesive 34-2 are arranged offset from each other may be manufactured by applying them in various ways.

[0145] As a result, in the electrode assembly 4 of this embodiment, the adhesive 34 is disposed between each electrode 3112, 3122 and the separator 322, and the adhesives 34 disposed in adjacent layers are staggered, thereby minimizing an increase in the thickness of the electrode assembly 4 due to the adhesive 34. At the same time, because the adhesives 34 disposed in adjacent layers are staggered, the adhesives 34 may be more easily dissolved in the electrolyte contained in the battery cell.

[0146] The adhesive 34 used in the electrode assemblies 3 and 4 shown in FIGS. 7 and 8 may be the first adhesive composition contained in the first adhesive portion 310 described above.

[0147] 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 claims also fall within the scope of the present invention. [Explanation of symbols]

[0148] 100: unit cell 110: 1st electrode 150: 2nd electrode 210: Lower separation membrane 250: Upper separation membrane 310: 1st adhesive part 350:Second adhesive part 1000: Battery cells 1100: Electrode assembly 2000: Battery case 3000: Electrode lead 4000: Lead film

Claims

1. A predetermined number of separators and electrodes are stacked alternately; a first adhesive portion located between the separator and the electrode and made of a first adhesive composition; and a second adhesive portion located between the separation membrane and another separation membrane and made of a second adhesive composition for fixing the separation membrane and the other separation membrane; The solubility of the first adhesive composition in the electrolyte is greater than the solubility of the second adhesive composition in the electrolyte, and the electrode assembly is formed by alternately stacking unit cells, and the electrolyte is included together; The first adhesive composition is made of at least one of an ethylene vinyl acetate (EVA)-based material, an acrylic-based material, and an epoxy-based material; The second adhesive composition is made of at least one of an ethylene vinyl acetate (EVA)-based material, an acrylic-based material, an epoxy-based material, a polyolefin-based material, a rubber-based material, a polyamide-based material, and a polyurethane-based material; a total content of the first adhesive composition and the second adhesive composition is 0.8 wt % or more and 1.2 wt % or less with respect to a content of the electrolytic solution; the total content of the first adhesive composition is 0.6 wt % or more and 0.9 wt % or less with respect to the content of the electrolyte solution; A battery cell, wherein the total content of the second adhesive composition is 0.1 wt % or more and 0.45 wt % or less with respect to the content of the electrolyte solution.

2. The separation membrane includes a lower separation membrane and an upper separation membrane, the electrodes include a first electrode and a second electrode; The battery cell according to claim 1 , wherein the lower separator, the first electrode, the upper separator, and the second electrode are stacked in this order.

3. 3. The battery cell of claim 2, wherein the first adhesive portion is located in at least one of between the first electrode and the lower separator, between the first electrode and the upper separator, and between the second electrode and the upper separator.

4. The battery cell according to claim 3 , wherein the second adhesive portion is located between the upper separator and the lower separator.

5. The battery cell according to claim 1 , wherein the first adhesive portion and the second adhesive portion are each formed in a pattern including a plurality of dots.

6. The battery cell of claim 5 , wherein the dots are spaced apart from one another.

7. The battery cell of claim 1 , wherein the first adhesive portion of the electrode assembly includes an adhesive pattern disposed at the same position between each of the electrodes and the separator.

8. The battery cell of claim 1 , wherein the first adhesive portion of the electrode assembly includes adhesive patterns disposed between the electrode and the separator in a staggered manner.

9. The battery cell according to claim 1 , wherein the first adhesive portion is dissolved in the electrolyte.

10. The battery cell of claim 1 , wherein the second adhesive composition is made of at least one of a rubber-based material, a polyamide-based material, and a polyurethane-based material.

11. The battery cell according to claim 10 , wherein the total content of the second adhesive composition is 0.1 wt % or more and 0.2 wt % or less with respect to the content of the electrolyte solution.

12. The battery cell of claim 1 , wherein the separator is folded to have a zigzag shape.

13. applying a first adhesive to at least one of a first surface of the electrode and a bonding area of ​​the first separator; applying the first adhesive to at least one of a second surface of the electrode or a bonding area of ​​a second separator, the second surface of the electrode being located on an opposite side of the electrode from the first surface; applying a second adhesive to at least one of the peripheral region of the first separator and the peripheral region of the second separator for fixing the first separator and the second separator; and forming a unit cell by stacking the electrode between the first separator and the second separator such that a first surface of the electrode contacts a bonding region of the first separator and a second surface of the electrode contacts a bonding region of the second separator; the unit cell is formed such that peripheral regions of the first separator and the second separator extend outward beyond the periphery of the electrode; The peripheral regions of the first and second separators face each other without an electrode therebetween, the solubility of the first adhesive in the electrolyte solution is greater than the solubility of the second adhesive in the electrolyte solution; forming an electrode assembly by alternately stacking the unit cells; and placing the electrode assembly and the electrolyte in a battery case; a total content of the first adhesive and the second adhesive in the battery case is 0.8 wt % or more and 1.2 wt % or less with respect to a total content of the electrolyte in the battery case; a total content of the first adhesive in the battery case is 0.6 wt % or more and 0.9 wt % or less with respect to a total content of the electrolyte in the battery case; a total content of the second adhesive in the battery case being 0.1 wt % or more and 0.45 wt % or less of the total content of the electrolyte in the battery case;

14. The method of claim 13 , wherein the solubility of the first adhesive in the electrolyte is greater than the solubility of the second adhesive in the electrolyte.

15. 14. The method of claim 13, wherein the peripheral regions of the first separator and the second separator extend around the periphery of the first separator and the second separator, respectively, and each of the peripheral regions surrounds a bonding region of the first separator and the second separator, respectively.

16. 14. The method of claim 13, wherein the first adhesive is made of at least one of an ethylene-vinyl acetate (EVA)-based material, an acrylic-based material, and an epoxy-based material, and the second adhesive is made of at least one of an ethylene-vinyl acetate (EVA)-based material, an acrylic-based material, an epoxy-based material, a polyolefin-based material, a rubber-based material, a polyamide-based material, and a polyurethane-based material.

17. The method of claim 13 , wherein the first adhesive and the second adhesive are applied in respective dot patterns spaced apart from each other.

18. The method of claim 17 , wherein the dot pattern of the first adhesive is arranged in a grid of rows and columns.

19. The method of claim 13 , further comprising dissolving at least a portion of the first adhesive in the electrolyte solution.

20. The method for manufacturing a battery cell according to claim 13 , wherein a total content of the first adhesive is 0.6 wt % or more and 0.9 wt % or less with respect to a total content of the electrolyte solution.

21. The method for manufacturing a battery cell according to claim 13 , wherein a total content of the second adhesive is 0.1 wt % or more and 0.45 wt % or less with respect to a total content of the electrolyte solution.

22. The method of claim 13 , wherein the second adhesive is made of at least one of a polyolefin-based material, a rubber-based material, a polyamide-based material, and a polyurethane-based material.

23. 23. The method for manufacturing a battery cell according to claim 22, wherein a total content of the second adhesive in the battery case is 0.1 wt % or more and 0.2 wt % or less of a total content of the electrolyte in the battery case.

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