Unit battery cell and battery cell comprising the same

Abstract

A unit cell according to one embodiment of the present application includes: separators and electrodes alternately stacked in a predetermined number; a first adhesive portion positioned between the separators and the electrodes and including a first adhesive component; and a second adhesive portion positioned between the separators and another separator and including a second adhesive component, wherein a shear strength of the first adhesive portion is equal to or less than a shear strength of the second adhesive portion.

Description

TECHNICAL FIELD

[0001] Cross Reference to Related Applications

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0066461, filed May 24, 2021, and Korean Patent Application No. 10-2022-0048387, filed April 19, 2022, the contents of which are incorporated herein by reference as part of the present application.

[0003] The present disclosure relates to a unit battery cell and a battery cell including the same, and more particularly, to a unit battery cell configured to adhere electrodes and separators and separators using an adhesive composition instead of a conventional lamination using heat and pressure, and a battery cell including the same. BACKGROUND

[0004] As technology has developed and the demand for mobile devices has increased, the demand for batteries as an energy source is rapidly increasing. In particular, secondary batteries have attracted considerable attention as an energy source for power-driven devices such as electric bicycles, electric vehicles, and hybrid electric vehicles, and as an energy source for mobile devices such as mobile phones, digital cameras, notebook computers, and wearable devices.

[0005] Based on the shape of the battery case, such a secondary battery can be classified into a cylindrical battery in which an electrode assembly is installed in a cylindrical metal can, a prismatic battery in which an electrode assembly is installed in a prismatic metal can, and a pouch-type battery in which an electrode assembly is installed in a pouch-type case formed of an aluminum-made laminate sheet. Here, the electrode assembly installed in the battery case is a power-generating element, the structure of which includes a cathode, an anode, and a separator interposed between the cathode and the anode, and is capable of charging and discharging. The electrode assembly can be classified into a jelly-roll type electrode assembly configured to have a structure in which a long sheet type cathode and a long sheet type anode, in which active materials are coated, are wound in a state in which a separator is interposed between the cathode and the anode, and a stacked type electrode assembly configured to have a structure in which a plurality of cathodes and anodes are sequentially stacked in a state in which a separator is interposed between the cathode and the anode.

[0006] Among them, in particular, the pouch-type battery having a structure in which a stacked / folded type electrode assembly is installed in a pouch-type battery case formed of an aluminum-made laminate sheet has advantages such as low manufacturing cost, small weight, and easy deformation of shape, and thus, the amount of use thereof is gradually increasing.

[0007] Here, in the case of a stacked electrode assembly, it is generally manufactured by preparing unit cells in advance and then stacking a plurality of unit cells. More specifically, the unit cells in a state of being alternately stacked in the order of separator-anode-separator-cathode can be fixed to each other by applying heat and pressure through a stacking device.

[0008] However, after being alternately stacked in the order of separator-anode-separator-cathode, a portion of the separator or the electrode is pushed out of position before entering the stacking device or during the stacking process, which causes a problem of breakage or a difference in adhesion strength.

[0009] Therefore, it is necessary to develop a unit cell capable of preventing movement between an electrode and a separator and preventing deformation and breakage of the electrode and the separator. SUMMARY

[0010] TECHNICAL PROBLEM

[0011] An object of the present disclosure is to provide a unit cell configured to adhere an electrode and a separator and a separator and a separator using an adhesive component instead of a conventional lamination using heat and pressure, and a battery cell including the same.

[0012] The object of the present disclosure is not limited to the above-described object, and other objects not described herein will be clearly understood by those skilled in the art from the following detailed description and accompanying drawings.

[0013] TECHNICAL SOLUTION

[0014] According to one embodiment of the present disclosure, a unit cell includes a separator and an electrode alternately stacked in a predetermined number, a first adhesive portion positioned between the separator and the electrode and including a first adhesive component, and a second adhesive portion positioned between the separator and another separator and including a second adhesive component, in which a shear strength of the first adhesive portion is equal to or less than a shear strength of the second adhesive portion.

[0015] The shear strength of the first adhesive portion can be 0.15 MPa or more and 0.5 MPa or less, and the shear strength of the second adhesive portion can be 0.15 MPa or more and 3.5 MPa or less.

[0016] The shear strength of the second adhesive portion can be 1.5 MPa or more and 3.5 MPa or less.

[0017] The viscosity of the first adhesive portion can be equal to or less than the viscosity of the second adhesive portion.

[0018] The viscosity of the first adhesive portion can be 50 cP@150℃ or more to 120 cP@150℃ or less, and the viscosity of the second adhesive portion can be 50 cP@150℃ or more to 12000 cP@150℃ or less.

[0019] The viscosity of the second adhesive portion can be 800 cP@150℃ or more and 12000 cP@150℃ or less.

[0020] The thickness of the first adhesive portion can be less than the thickness of the electrode, and the thickness of the second adhesive portion can be equal to or less than the thickness of the electrode.

[0021] The thickness of the first adhesive portion can be 0.01% or more to 10% or less with respect to the thickness of the electrode, and the thickness of the second adhesive portion can be 90% or more to 100% or less with respect to the thickness of the electrode.

[0022] The adhesive strength of the first adhesive portion can be equal to or greater than the adhesive strength of the second adhesive portion.

[0023] The adhesive strength of the first adhesive portion can be from 50 gf / mm 2 to 100 gf / mm 2 , and the adhesive strength of the second adhesive portion can be 20 gf / mm 2 to 100 gf / mm 2 .

[0024] The second adhesive portion can be positioned between an end of the separator and an end of the electrode.

[0025] The width of the second adhesive portion can be less than a distance between the end of the separator and the end of the electrode.

[0026] The first adhesive portion and the second adhesive portion can each be formed in a pattern including a plurality of dots spaced apart from each other.

[0027] The diameter of the plurality of dots included in the second adhesive portion can be less than a distance between the end of the electrode and the end of the separator.

[0028] The first adhesive ingredient can include at least one of an ethylene-vinyl acetate (EVA)-based material, an acrylic-based material, and an epoxy-based material, and the second adhesive ingredient can include 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.

[0029] The second adhesive component can include at least one of a polyolefin-based material, a rubber-based material, a polyamide-based material, and a polyurethane-based material.

[0030] According to another embodiment of the present disclosure, there is provided an electrode assembly formed by alternately stacking the unit cells, the first adhesive portion including an adhesive pattern arranged in the same position between the electrode and the separator.

[0031] According to another embodiment of the present disclosure, there is provided an electrode assembly formed by alternately stacking the unit cells, the first adhesive portion including an adhesive pattern arranged in a staggered form between the electrode and the separator.

[0032] According to another embodiment of the present disclosure, there is provided a battery cell including an electrolyte solution and an electrode assembly in which the unit cells are alternately stacked.

[0033] The first adhesive portion can have a property of being dissolved in the electrolyte.

[0034] The battery cell can have a zigzag shape by folding the separator.

[0035] According to another embodiment of the present disclosure, there is provided a method of manufacturing a unit cell, the method including the steps of: applying a first adhesive to a first face of an electrode or to an adjoining region of a first separator, or to both; applying the first adhesive to a second face of the electrode, which is located on an opposite side of the first face of the electrode, or to an adjoining region of a second separator, or to both; applying a second adhesive to a peripheral region of the first separator or to a peripheral region of the second separator, or to both; and forming at least a portion of a stack by stacking the electrode between the first separator and the second separator such that the first face of the electrode adjoins the adjoining region of the first separator and the second face of the electrode adjoins the adjoining region of the second separator, the stack being formed such that the peripheral region of each of the first separator and the second separator extends outward beyond edges of the electrode, the peripheral regions of each of the first separator and the second separator facing each other without the electrode interposed therebetween, wherein a shear strength of the first adhesive is less than or equal to a shear strength of the second adhesive.

[0036] The method of manufacturing a unit cell can further include compressing the stack in a direction orthogonal to the first face and the second face of the electrode.

[0037] The method of manufacturing a unit cell can further include positioning the stack and electrolyte in a battery case.

[0038] The peripheral region of each of the first and second separators can extend around a perimeter of the respective first and second separators, such that each of the peripheral regions encircles the abutment region of the respective first and second separators.

[0039] The first adhesive can have a shear strength greater than or equal to 0.15 MPa and less than or equal to 0.5 MPa, and the second adhesive can have a shear strength greater than or equal to 0.15 MPa and less than or equal to 3.5 MPa.

[0040] The second adhesive can have a shear strength greater than or equal to 1.5 MPa and less than or equal to 3.5 MPa.

[0041] The first adhesive can have a viscosity less than or equal to a viscosity of the second adhesive.

[0042] The first adhesive can have a viscosity greater than or equal to 50 cP @ 150°C and less than or equal to 120 cP @ 150°C, and the second adhesive can have a viscosity greater than or equal to 50 cP @ 150°C and less than or equal to 1200 cP @ 150°C.

[0043] The second adhesive can have a viscosity greater than or equal to 800 cP @ 150°C and less than or equal to 1200 cP @ 150°C.

[0044] The first adhesive can have a thickness less than a thickness of the electrode, and the second adhesive can have a thickness less than or equal to the thickness of the electrode.

[0045] The first adhesive can have a thickness greater than or equal to 0.01% of the thickness of the electrode and less than or equal to 10% of the thickness of the electrode, and the second adhesive can have a thickness greater than or equal to 90% of the thickness of the electrode and less than or equal to 100% of the thickness of the electrode.

[0046] The first adhesive can have a cohesive strength greater than or equal to a cohesive strength of the second adhesive.

[0047] The first adhesive can have a cohesive strength greater than or equal to 50 gf / mm 2 and less than or equal to 100 gf / mm 2 , and the second adhesive can have a cohesive strength greater than or equal to 20 gf / mm 2 and less than or equal to 100 gf / mm 2 .

[0048] A width of the second adhesive applied to the peripheral region of the first or second separator can be less than a width of the peripheral region to which the second adhesive is applied.

[0049] The first and second adhesives can each be applied in a respective dot pattern, the dots being spaced apart from one another.

[0050] A diameter of each dot in the dot pattern of the second adhesive can be less than the width of the peripheral region.

[0051] The dots in the dot pattern of the first adhesive can be arranged in a grid of rows and columns of dots.

[0052] The first adhesive can comprise at least one of an ethylene-vinyl acetate (EVA)-based material, an acrylic-based material, and an epoxy-based material, and the second adhesive comprises at least one of an ethylene-vinyl acetate (EVA)-based material, an acrylic-based material, and an epoxy-based material, a polyolefin-based material, a rubber-based material, a polyamide-based material, and a polyurethane-based material.

[0053] The second adhesive can comprise at least one of a polyolefin-based material, a rubber-based material, a polyamide-based material, and a polyurethane-based material.

[0054] Advantageous Effects

[0055] According to embodiments, the unit battery cell and the battery cell including the same of the present disclosure are configured to adhere the electrode and the separator and the separator and the separator using an adhesive composition instead of conventional lamination using heat and pressure, thereby preventing movement between the electrode and the separator and preventing deformation and breakage of the electrode and the separator.

[0056] Effects of the present disclosure are not limited to the above-described effects, and other additional effects not described above can be clearly understood by those skilled in the art from the description of the appended claims. BRIEF DESCRIPTION OF DRAWINGS

[0057] Figure 1 is an exploded perspective view of a unit battery cell according to an embodiment of the present disclosure;

[0058] Figure 2 is a perspective view of a unit battery cell in which Figure 1 components are combined;

[0059] Figure 3 is a sectional view taken along an A-A axis of Figure 2 ;

[0060] Figure 4 is a sectional view of a pressing process of the unit battery cell of Figure 2 ;

[0061] Figure 5 It is shown that it includes Figure 2 A diagram illustrating the application process of the first and second adhesive portions in a cell.

[0062] Figure 6 This is a top view of a battery cell according to another embodiment of the present disclosure;

[0063] Figure 7 It is shown Figure 2 A linear sweep voltammetry (LSV) view of the binder components included in the cell;

[0064] Figure 8 This is a cross-sectional view showing an electrode assembly according to one embodiment of the present disclosure; and

[0065] Figure 9 This is a cross-sectional view showing an electrode assembly according to another embodiment of the present disclosure. Detailed Implementation

[0066] Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings to enable those skilled in the art to readily implement these embodiments. The disclosed embodiments may be modified in various different ways without departing from the spirit or scope of the present disclosure.

[0067] Parts irrelevant to the description will be omitted in order to clearly describe this disclosure. Throughout the specification, similar reference numerals indicate similar elements.

[0068] Furthermore, for ease of description, the dimensions and thicknesses of each element are shown arbitrarily in the figures, and this disclosure is not necessarily limited to those shown in the figures. In the figures, the thicknesses of layers, regions, etc., are exaggerated for clarity. In the figures, the thicknesses of some layers and regions are exaggerated for ease of description.

[0069] Furthermore, throughout the specification, when a section is referred to as "including" a component, it means that the section includes the said component but does not exclude any other components, unless explicitly stated otherwise.

[0070] Furthermore, throughout the instruction manual, when referred to as a "plane," it means when viewing the target portion from above; when referred to as a "section," it means when viewing the target portion from a vertically cut section.

[0071] The following will describe a cell according to one embodiment of the present disclosure.

[0072] Figure 1 This is an exploded perspective view of a cell according to one embodiment of the present disclosure. Figure 2 It is shown that Figure 1a perspective view of a unit cell in which components are combined. Figure 3 is cut along Figure 2 an A-A axis.

[0073] Referring to Figure 1 and Figure 2 A unit cell according to one embodiment of the disclosure includes: separators 210 and 250 and electrodes 110 and 150 which are alternately stacked in a predetermined number; a first adhesive portion 310 positioned between the separators 210 and 250 and the electrodes 110 and 150 and containing a first adhesive component; and a second adhesive portion 350 positioned between the separators 210 and 250 and other separators 210 and 250 and containing a second adhesive component.

[0074] More specifically, the separators 210 and 250 include a lower separator 210 and an upper separator 250, and the electrodes 110 and 150 include a first electrode 110 and a second electrode 150, wherein the lower separator 210, the first electrode 110, the upper separator 250, and the second electrode 150 can be stacked in this order.

[0075] Here, the first electrode 110 can include a first electrode tab 115 protruding in one direction, and the second electrode 150 can include a second electrode tab 155 protruding in one direction. In one embodiment, as shown in Figure 1 and Figure 3 , the stacking can be performed such that the upper separator 250 is positioned between the first electrode 110 and the second electrode 150, and the stacking can be performed such that the first electrode tab 115 of the first electrode 110 and the second electrode tab 155 of the second electrode 150 are positioned in opposite directions to each other. However, the disclosure is not limited thereto, and a structure in which the first electrode tab 115 and the second electrode tab 155 are stacked to be positioned in the same direction can also be included in an embodiment of the disclosure.

[0076] Here, the first electrode 110 and the second electrode 150 can each include an electrode current collector and an active material layer positioned on the electrode current collector. Here, the active material layer can be formed of an electrode component containing an electrode active material. More specifically, the first electrode 110 and the second electrode 150 can be a cathode and an anode. Here, the cathode can include a cathode current collector and an active material layer containing a cathode active material, and the anode can include an anode current collector and an active material layer containing an anode active material. In one embodiment, the first electrode 110 can be an anode, and the second electrode 150 can be a cathode, but the disclosure is not limited thereto, and a case in which the first electrode 110 can be a cathode, and the second electrode 150 can be an anode can also be included in an embodiment of the disclosure.

[0077] As the anode active material, an anode active material of a lithium secondary battery well known in the art can be used, and as one embodiment, a material such as metallic lithium, lithium alloy, petroleum coke, activated carbon, graphite, silicon, tin, metal oxide, or other carbon can be used.

[0078] Further, in one embodiment, the cathode active material can be 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 can be a combination or a composite oxide thereof.

[0079] The anode current collector or the cathode current collector is not particularly limited as long as it has high conductivity while not causing chemical changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, or the like can be used.

[0080] The separators 210 and 250 can separate the first electrode 110 and the second electrode 150 and provide a moving path for lithium ions. Further, the separators 210 and 250 include a lower separator 210 and an upper separator 250, and separators made of different or the same materials from each other can be applied as the lower separator 210 and the upper separator 250.

[0081] In one embodiment, the separators 210 and 250 can be used without particular limitation as long as they are generally used as separators in lithium secondary batteries. In particular, it is desirable for the separators to have low resistance to ion movement of an electrolyte solution and to be excellent in terms of the moisture retaining capacity of the electrolyte solution. Specifically, a porous polymer film made of a polyolefin-based polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butylene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer can be used alone, or a stacked structure having two or more layers thereof can be used.

[0082] Hereinafter, the first adhesive portion 310 and the second adhesive portion 350 included in the unit cell according to the embodiment of the disclosure will be mainly described.

[0083] Referring to Figure 1 and Figure 3 , the first adhesive portion 310 can be positioned at at least one position selected from 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.

[0084] The first adhesive portion 310 can include a first adhesive component, and the second adhesive portion 350 can include a second adhesive component. In one embodiment, the first adhesive component can include at least one of an ethylene-vinyl acetate (EVA)-based material, an acrylic-based material, and an epoxy-based material, and the second adhesive component can include 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. More preferably, the second adhesive component can include at least one of the polyolefin-based material, the rubber-based material, the polyamide-based material, and the polyurethane-based material among the above-described materials.

[0085] Accordingly, the first adhesive portion 310 can fix the first electrode 110 and the second electrode 150 to the lower separator 210 and / or the upper separator 250, respectively. That is, unlike a conventional lamination process, the first adhesive portion 310 can prevent movement between the electrodes 110 and 150 and the separators 210 and 250, and prevent deformation and breakage of the electrodes 110 and 150 and the separators 210 and 250.

[0086] Referring to Figure 4 and Figure 4 , the first adhesive portion 310 and the second adhesive portion 350 can have different physical properties and physical conditions from each other because their formed positions are different from each other.

[0087] The shear strength of the first adhesive portion 310 can be equal to or less than the shear strength of the second adhesive portion 350. Here, the shear strength of the first adhesive portion 310 can be 0.15 MPa or more and 0.5 MPa or less, and the shear strength of the second adhesive portion 350 can be 0.15 MPa or more and 3.5 MPa or less.

[0088] In one embodiment, the shear strength of the first adhesive portion 310 and the shear strength of the second adhesive portion 350 can be 0.15 MPa or more and 0.5 MPa or less. More specifically, the shear strength of the first adhesive portion 310 and the shear strength of the second adhesive portion 350 can be 0.2 MPa or more and 0.5 MPa or less.

[0089] Accordingly, the first adhesive portion 310 and the second adhesive portion 350 have shear strengths in the above-described ranges, so that the first adhesive portion 310 and the second adhesive portion 350 can be easily pressed by the pressure rollers 510 and 520, Figure 4 ), respectively.

[0090] In contrast, when the shear strength of the first adhesive portion 310 and the second adhesive portion 350 is less than 0.15 MPa, adhesion and fixation between the electrodes 110 and 150 and the separators 210 and 250 can not be favorable. Also, when the shear strength of the first adhesive portion 310 and the second adhesive portion 350 exceeds 0.5 MPa, the first adhesive portion 310 can not be easily pressed by the pressure rollers 510 and 520 ( Figure 4 ), and thus the first thickness d1 of the first adhesive portion 310 can be too large or uneven.

[0091] In another embodiment, the shear strength of the first adhesive portion 310 can be 0.15 MPa or more and 0.5 MPa or less, and the shear strength of the second adhesive portion 350 can be 1.5 MPa or more and 3.5 MPa or less. More specifically, the shear strength of the first adhesive portion 310 can be 0.2 MPa or more and 0.5 MPa or less, and the shear strength of the second adhesive portion 350 can be 2.0 MPa or more and 3.5 MPa or less.

[0092] Accordingly, the first adhesive portion 310 and the second adhesive portion 350 have shear strengths within the above-described ranges, and thus the second adhesive portion 350 and the first adhesive portion 310 can be easily pressed by the pressure rollers 510 and 520 ( Figure 3 ), respectively. Also, the shear strength of the second adhesive portion 350 is greater than that of the first adhesive portion 310, and thus a phenomenon in which a portion of the second adhesive portion 350 comes into contact with the electrodes 110 and 150 or leaks outside the end portions of the separators 210 and 250 can be prevented in advance.

[0093] In contrast, when the shear strength of the second adhesive portion 350 is less than 1.5 MPa, the second adhesive portion 350 spreads to both sides in some processes, which causes a problem in which a portion of the second adhesive portion 350 comes into contact with the electrodes 110 and 150 or leaks outside the end portions of the separators 210 and 250. Also, when the shear strength of the second adhesive portion 350 exceeds 3.5 MPa, the second adhesive portion 350 can not be easily pressed by the pressure rollers 510 and 520 ( Figure 4 ), and thus the second thickness d2 of the second adhesive portion 350 can be too large or uneven.

[0094] Also, the first thickness d1 of the first adhesive portion 310 can be less than the second thickness d2 of the second adhesive portion 350. More specifically, the first thickness d1 of the first adhesive portion 310 is less than the thickness D1 of the electrodes 110 and 150, and the second thickness d2 of the second adhesive portion 350 can be equal to or greater than the thickness D1 of the electrodes 110 and 150. In one embodiment, as Figure 2As shown in the middle, the first thickness d1 of the first adhesive portion 310 is less than the thickness D1 of the first electrode 110, and the second thickness d2 of the second adhesive portion 350 can be equal to or less than the thickness D1 of the first electrode 110.

[0095] Accordingly, the first adhesive portion 310 has a relatively small thickness, and thus the gap that can be generated between the electrodes 110 and 150 and the separators 210 and 250 can be reduced, and the space efficiency of the unit cell 100 can be improved. In addition, the thickness of the second adhesive portion 350 is similar to the thickness of the first electrode 110, and thus the thickness of the unit cell 100 can be relatively uniform, while being easily adhered and fixed between the lower separator 210 and the upper separator 250.

[0096] In addition, the first thickness d1 of the first adhesive portion 310 can be 0.01% or more and 10% or less with respect to the thickness D1 of the electrodes 110 and 150. More specifically, the first thickness d1 of the first adhesive portion 310 can be 0.05% or more and 8% or less with respect to the thickness D1 of the electrodes 110 and 150. In one embodiment, the first thickness d1 of the first adhesive portion 310 can be 1% or more and 5.0% or less with respect to the thickness D1 of the electrodes 110 and 150.

[0097] Accordingly, the first thickness d1 of the first adhesive portion 310 has a ratio within the above range with respect to the thickness D1 of the electrodes 110 and 150, and thus the thickness of the unit cell 100 can be relatively uniform, while being easily adhered and fixed between the electrodes 110 and 150 and the separators 210 and 250.

[0098] In contrast, when the first thickness d1 of the first adhesive portion 310 is less than 0.01% with respect to the thickness D1 of the electrodes 110 and 150, the fixing force between the electrodes 110 and 150 and the separators 210 and 250 is not sufficient, which causes a problem in which the electrodes 110 and 150 and the separators 210 and 250 are separated from each other in a subsequent process. In addition, when the first thickness d1 of the first adhesive portion 310 is greater than 10% of the thickness D1 of the electrodes 110 and 150, the gap between the electrodes 110 and 150 and the separators 210 and 250 is too large, which causes a problem in which the space efficiency and the battery capacity of the unit cell 100 are reduced.

[0099] Figure 3 is a cross-sectional view illustrating a pressing process of a unit cell. Figure 4

[0100] In addition, with reference to Figure 5 and Figure 2 ​, the first thickness d1 of the first adhesive portion 310 and the second thickness d2 of the second adhesive portion 350 can be thicknesses after being pressed by the pressure rollers 510 and 520 in the vertical and lateral directions of the unit battery 100. Here, the pressure rollers 510 and 520 can be rollers such as nip rollers, and can press the unit battery 100 in the vertical and lateral directions of the unit battery 100.

[0101] Here, in the unit battery 100 before being pressed by the pressure rollers 510 and 520, the third thickness d3 of the first adhesive portion 310 can be greater than the first thickness d1 of the first adhesive portion 310. More specifically, the third thickness d3 of the first adhesive portion 310 can be 40% or more to 60% or less with respect to the thickness D1 of the electrodes 110 and 150. In one embodiment, the third thickness d3 of the first adhesive portion 310 can be 45% or more to 55% or less with respect to the thickness D1 of the electrodes 110 and 150.

[0102] Further, the fourth thickness d4 of the second adhesive portion 350 can be greater than the second thickness d2. More specifically, the fourth thickness d4 of the second adhesive portion 350 can be 90% or more and 105% or less with respect to the thickness D1 of the electrodes 110 and 150. In one embodiment, the fourth thickness d4 of the second adhesive portion 350 can be 95% or more and 105% or less with respect to the thickness D1 of the electrodes 110 and 150.

[0103] Accordingly, the thicknesses of the first adhesive portion 310 and the second adhesive portion 350 before being pressed by the pressure rollers 510 and 520 can have a thickness ratio within the above-described range, whereby the thickness of the unit battery 100 can be relatively uniform even after the unit battery 100 is pressed by the pressure rollers 510 and 520, while being easily adhered and fixed between the separators 210 and 250 or between the electrodes 110 and 150 and the separators 210 and 250.

[0104] Further, the adhesive strength of the first adhesive portion 310 and the second adhesive portion 350 can be equal to or greater than the adhesive strength of the second adhesive portion 350. Here, the adhesive strength of the first adhesive portion 310 and the second adhesive portion 350 can be measured by applying the first adhesive component and the second adhesive component in the form of 15 spaced 3 mm points between a pair of tension clamps prepared in advance, and then peeling it vertically.

[0105] At this time, the adhesive strength of the first adhesive portion 310 can be 50 gf / mm 2 or more to 100 gf / mm 2 or less, and the adhesive strength of the second adhesive portion 350 can be 20 gf / mm 2 or more to 100 gf / mm2 More specifically, the adhesive strength of the first adhesive portion 310 can be 55 gf / mm 2 above and 95 gf / mm 2 above and 95 gf / mm 2 above and 95 gf / mm 2 above and 95 gf / mm 2 above and 90 gf / mm 2 above and 90 gf / mm 2 above and 90 gf / mm 2 above.

[0106] Accordingly, the first adhesive portion 310 and the second adhesive portion 350 have adhesive strengths within the above ranges, and thus the first adhesive portion 310 and the second adhesive portion 350 can each be easily adhered and fixed between the separators 210 and 250 or between the electrodes 110 and 150 and the separators 210 and 250.

[0107] In contrast, when the adhesive strength of the first adhesive portion 310 is less than 50 gf / mm 2 or greater than 100 gf / mm 2 , there is a problem in that the electrodes 110 and 150 and the separators 210 and 250 are detached from each other in a subsequent process or a manufacturing process is difficult. In addition, when the adhesive strength of the second adhesive portion 350 is less than 20 gf / mm 2 or greater than 100 gf / mm 2 , there is a problem in that the upper separator 250 and the lower separator 210 are detached from each other in a subsequent process or a manufacturing process is difficult.

[0108] Figure 3 is a view illustrating an application process of the first adhesive portion and the second adhesive portion included in the unit cell of Figure 5

[0109] In addition, the viscosity of the first adhesive portion 310 can be equal to or less than the viscosity of the second adhesive portion 350. More specifically, with reference to Figure 4 and Figure 1 ​The first adhesive portion 310 and the second adhesive portion 350 can be applied to the electrodes 110 and 150 and / or the separators 210 and 250 by means of the coating device 600. In one embodiment, the coating device 600 can be a device such as an inkjet device, and the coating device 600 can include a housing 610 causing a volume change of an internal pressure chamber, a wall surface 620 reducing the volume of the pressure chamber, and an outlet port 610a discharging the adhesive composition. That is, the viscosity of the first adhesive portion 310 and the second adhesive portion 350 can be a discharge viscosity discharged from the outlet port 610a of the coating device 600.

[0110] More specifically, the viscosity of the first adhesive portion 310 and the second adhesive portion 350 can be a viscosity (cP@150℃) discharged from the outlet port 610a of the coating device 600 at 150 degrees Celsius. Here, the viscosity of the first adhesive portion 310 can be 50 cP@150℃ or more to 120 cP@150℃ or less, and the viscosity of the second adhesive portion 350 can be 50 cP@150℃ or more to 12000 cP@150℃ or less.

[0111] In one embodiment, the viscosity of the first adhesive portion 310 and the viscosity of the second adhesive portion 350 can be 60 cP@150℃ or more to 110 cP@150℃ or less, respectively. More specifically, the viscosity of the first adhesive portion 310 and the viscosity of the second adhesive portion 350 can be 70 cP@150℃ or more and 100 cP@150℃ or less, respectively.

[0112] Accordingly, the first adhesive portion 310 and the second adhesive portion 350 have the viscosity within the above range, whereby the first adhesive portion 310 and the second adhesive portion 350 each have an adhesive strength capable of being easily adhered and fixed between the separators 210 and 250 or between the electrodes 110 and 150 and the separators 210 and 250, respectively, and also can improve discharge stability of the coating device 600.

[0113] In contrast, when the viscosity of the first adhesive portion 310 and the second adhesive portion 350 is less than 60 cP@150℃, adhesion and fixation between the electrodes 110 and 150 and the separators 210 and 250 can be disadvantageous. In addition, when the viscosity of the first adhesive portion 310 and the second adhesive portion 350 exceeds 120 cP@150℃, the first adhesive portion 310 can not be easily pressed by the pressure rollers 510 and 520 (510a and 520a) and thus the first thickness d1 of the first adhesive portion 310 can be too large or non-uniform. Figure 3

[0114] ​In another embodiment, the viscosity of the first adhesive portion 310 can be 60 cP@150℃ or more to 110 cP@150℃ or less, and the viscosity of the second adhesive portion 350 can be 800 cP@150℃ or more to 12000 cP@150℃ or less. More specifically, the viscosity of the first adhesive portion 310 can be 70 cP@150℃ or more to 100 cP@150℃ or less, and the viscosity of the second adhesive portion 350 can be 850 cP@150℃ or more to 11000 cP@150℃ or less.

[0115] Therefore, since the first adhesive portion 310 and the second adhesive portion 350 have the viscosity within the above range, the first adhesive portion 310 and the second adhesive portion 350 each have an adhesive strength capable of being easily adhered and fixed between the separators 210 and 250 or between the electrodes 110 and 150 and the separators 210 and 250, respectively, and also can improve the discharge stability of the coating apparatus 600. Further, since the viscosity of the second adhesive portion 350 is greater than that of the first adhesive portion 310, it is possible to prevent in advance a phenomenon in which a portion of the second adhesive portion 350 comes into contact with the electrodes 110 and 150 or leaks outside the end portions of the separators 210 and 250.

[0116] Unlike this, when the viscosity of the second adhesive portion 350 is less than 800 cP@150℃, the second adhesive portion 350 spreads to both sides in some processes, which causes a problem in which a portion of the second adhesive portion 350 comes into contact with the electrodes 110 and 150 or leaks outside the end portions of the separators 210 and 250. Further, when the viscosity of the second adhesive portion 350 is greater than 12000 cP@150℃, there is a problem in that the discharge stability of the coating apparatus 600 is reduced.

[0117] Here, the first width r1 of the second adhesive portion 350 can be less than the distance D2 between the end portions of the separators 210 and 250 and the end portions of the electrodes 110 and 150. More specifically, the first width r1 of the second adhesive portion 350 can be a width after the second adhesive portion 350 is pressed by the pressure rollers 510 and 520 in the vertical and both side directions of the unit battery cell 100. That is, the first width r1 of the second adhesive portion 350 can be greater than a second width r2 of the second adhesive portion 350 before the second adhesive portion 350 is pressed by the pressure rollers 510 and 520.

[0118] Therefore, the first width r1 of the second adhesive portion 350 is less than the distance D2 between the end portions of the separators 210 and 250 and the end portions of the electrodes 110 and 150, whereby it is possible to prevent a phenomenon in which a portion of the second adhesive portion 350 comes into contact with the electrodes 110 and 150 or leaks outside the end portions of the separators 210 and 250 even after the second adhesive portion 350 is pressed by the pressure rollers 510 and 520.

[0119] In addition, the first adhesive portion 310 and the second adhesive portion 350 can form a pattern including a plurality of points spaced apart from each other, as shown in FIGS. 1B and 1C. Figure 4 and Figure 4 Here, if necessary, the intervals between the plurality of points can be adjusted to be the same as or different from each other.

[0120] Accordingly, the first adhesive portion 310 and the second adhesive portion 350 can form the above-described pattern, whereby, when an electrolyte solution is injected into the electrode assembly 1100( Figure 4 ) including a plurality of unit battery cells 100, there is an advantage in that the electrode assembly 1100( Figure 6 ) can be quickly impregnated. More specifically, since the plurality of points are spaced apart from each other in the first adhesive portion 310 and the second adhesive portion 350, there is an advantage in that the electrolyte solution can flow between the plurality of points. That is, the manufacturing time of the battery cell 1000( Figure 7 ) can be relatively shortened, and the yield can also be improved.

[0121] The first adhesive portion 310 can block the passage of lithium ions between the electrodes 110 and 150 and the separators 210 and 250. To prevent this, it can be preferable that the first adhesive portion 310 be made of a material having a relatively high solubility in the electrolyte solution.

[0122] According to one embodiment, the first adhesive portion 310 and the second adhesive portion 350 can include materials having different compositions from each other. In one embodiment, a first adhesive component forming the first adhesive portion 310 can include at least one of an ethylene-vinyl acetate (EVA)-based material, an acrylic-based material, and an epoxy-based material, and a second adhesive component forming the second adhesive portion 350 can include at least one of a polyolefin-based material, a rubber-based material, a polyamide-based material, and a polyurethane-based material. For example, when the first adhesive component is made of an acrylic material, it can be considered to exhibit a certain solubility in the electrolyte since the acrylic material includes an ester group.

[0123] Accordingly, when an electrolyte solution is injected into the electrode assembly 1100( Figure 7 ) including a plurality of unit battery cells 100, the first adhesive component included in the first adhesive portion 310 can be dissolved between the electrodes 110 and 150 and the separators 210 and 250. That is, in this case, the first adhesive portion 310 positioned between the electrodes 110 and 150 and the separators 210 and 250 is dissolved in the electrolyte solution, so that it can block the passage of lithium ions between the electrodes 110 and 150 and the separators 210 and 250.

[0124] Here, the diameter of the plurality of points included in the second adhesive portion 350 can be smaller than the distance D2 between the end portions of the electrodes 110 and 150 and the end portions of the separators 210 and 250. Here, the diameter of the second adhesive portion 350 can be interpreted in the same manner as the width r1 and r2 of the second adhesive portion 350 described above.

[0125] Referring to Figure 6 Unlike the first adhesive component included in the first adhesive portion 310 corresponding to the first position, in the case of the second adhesive component included in the second adhesive portion 350 corresponding to the second position, it is confirmed that oxidation reaction occurs at about 4.0 V according to the result of linear sweep voltammetry (LSV). This can cause a side reaction in the battery cell, which can be a factor in reducing capacity and lifespan. Therefore, it is not preferable to use the second adhesive component for the first adhesive portion 310. One of the reasons for forming the second adhesive portion 350 is to prevent the folding of the separator caused in the electrolyte injection process. When at least one of an ethylene-vinyl acetate material, an acrylic material, and an epoxy-based material is used as the first adhesive component, and a polyolefin-based material, a rubber-based material, a polyamide-based material, and a polyurethane-based material are used as the second adhesive component, the result shown in Table 1 below can occur. Figure 2

[0126] The separator according to the embodiments described herein can be a ceramic-coated separator (CCS). In general, the separator has a base film and a coating layer formed on at least one surface of the base film, and the coating layer can include alumina powder and a binder to aggregate them. In a safety reinforced separator (SRS), a large amount of binder is coated on the surface of the coating layer, but in the CCS, the binder is not coated on the surface of the coating layer, or the binder content distributed on the surface can be very low compared to the SRS. For example, in the case of the CCS separator according to the present embodiment, the content of the binder coated on the surface of the coating layer of the separator can be about 3 wt% or less.

[0127] When the separator is a CCS, since the internal electrode included in the electrode assembly is transported in a non-fixed state, the alignment can be disturbed during the transportation process. Of course, when the separator is a CCS, it is possible to fix by means of heat and pressure, but even after forming a laminate of the electrode and the separator, the process of transferring the electrode and the separator to a fixing device of heating and pressurization, the alignment of the internal electrode can be disturbed. In addition, there is a disadvantage in that an expensive separator having a high binder content must be used to attach the electrode and the separator by means of heat and pressure. On the other hand, according to the present embodiment, it is possible to increase the fixing force while preventing the alignment of the internal electrode from being disturbed during the transportation process.

[0128] Figure 6 ​is a top view of a battery cell according to another embodiment of the disclosure.

[0129] Referring to Figure 8 and Figure 8 A battery cell 1000 according to another embodiment of the disclosure includes an electrode assembly 1100 on which unit cells 100 are alternately stacked, and an electrolyte solution. Here, a first electrode tab 1150 on which the first electrode tab 115 of the unit cell 100 is stacked and a second electrode tab 1550 on which the second electrode tab 155 is stacked can be electrically connected to an electrode lead 3000, respectively. A lead film 4000 can be positioned above and / or below the electrode lead 3000.

[0130] Further, the electrode assembly 1100 is mounted within a battery case 120, in which the electrode assembly 1100 can be positioned within a receiving portion 2100 having a concave shape together with the electrolyte solution. Further, a sealing portion 2500 can be formed such that the peripheral surfaces of the battery case 2000 are heat fusion sealed to each other.

[0131] In one embodiment, the electrolyte solution can include at least one of an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel polymer electrolyte, a solid inorganic electrolyte, an inorganic molten electrolyte, etc., but the disclosure is not limited thereto and can include all electrolyte solutions commonly used in the art.

[0132] Hereinafter, the disclosure will be described with reference to more specific embodiments, but the scope of the right of the disclosure is not limited to the following embodiments for the purpose of illustration only.

[0133] <Experimental Example 1 - Measurement of Shear Strength, Viscosity, and Adhesion Strength>

[0134] The shear strength, viscosity, and adhesion strength of ethylene-vinyl acetate (EVA)-based material, acrylic-based material, epoxy-based material, polyolefin-based material, rubber-based material, polyamide-based material, and polyurethane-based material, which are adhesive components, respectively, were measured.

[0135] Here, the acrylic-based material is acResin 204UV of BASF, the EVA-based material is Technomelt 4046 of Henkel, the epoxy-based material is Lotite EA608 of Henkel, the polyolefin-based material is Supra 502 of Henkel, the rubber-based material is 2802dispomelt f of Henkel, the polyamide-based material is HPX 002 of Henkel, and the polyurethane-based material is EH9702 of Fuller.

[0136] Shear strength was measured with a universal testing machine (UTM) according to the ASTM D3163 standard.

[0137] The spindle portion of a Brookfield DV2T LV TJ10 machine was replaced with a cone plate and CPA-40Z cone was applied to measure viscosity at 10 rpm. The results are shown in Table 1 below.

[0138] The adhesive strength was measured by applying one of the above adhesive components in the form of 15 points spaced 3 mm apart between a pair of tension grips prepared in advance, and then peeling it vertically. The results are shown in Table 1 below.

[0139] [Table 1]

[0140]

[0141] [Example 1]

[0142] LiNi 0.6 Mn 0.2 Co 0.2 O2 was used as a cathode active material, carbon black was used as a conductive material, and polyvinylidene fluoride (PVdF) was used as a binder, and NMP was added as a solvent to a mixture of the cathode active material: conductive material: binder in a weight ratio of 96:2:2 to prepare a cathode active material slurry. The cathode active material slurry was applied to an aluminum current collector, and then dried and rolled to manufacture a cathode. Here, the thickness of the cathode was 200 µm.

[0143] Artificial graphite was used as an anode active material, carbon black was used as a conductive material, and an SBR emulsion aqueous solution was used as a binder, and water was added to a mixture of the anode active material: conductive material: binder in a weight ratio of 94:1:5 to prepare an anode active material slurry. The anode active material slurry was applied to a copper current collector, and then dried and rolled to manufacture an anode. Here, the thickness of the anode was 200 µm.

[0144] A slurry of Al2O3 and PVDF mixed in a weight ratio of 94:6 was applied to both sides (each thickness of 3 µm) of a substrate (thickness of 10 µm) made of polyethylene / polypropylene, and dried at 60°C to manufacture a separator. According to the position, the separator was a top separator and a bottom separator.

[0145] The manufactured bottom separator, anode, top separator, and cathode were alternately stacked in this order to manufacture a unit cell in which a first adhesive portion containing acResin 204UV was positioned between the separator and the anode and between the separator and the cathode, and a second adhesive portion containing acResin 204UV was positioned between the top separator and the bottom separator.

[0146] <Example 2>

[0147] Unit cells were manufactured in the same manner as Example 1, except that the second adhesive portion used a composition comprising Supra 502, unlike Example 1.

[0148] <Example 3>

[0149] Unit cells were manufactured in the same manner as Example 1, except that the first adhesive portion used a composition comprising Lotite EA 608, and the second adhesive portion used a composition comprising Supra 502, unlike Example 1.

[0150] <Example 4>

[0151] Unit cells were manufactured in the same manner as Example 1, except that the first adhesive portion used a composition comprising Technomelt 4046, and the second adhesive portion used a composition comprising Supra 502, unlike Example 1.

[0152] <Comparative Example 1>

[0153] Unit cells were manufactured in the same manner as Example 1, except that the first adhesive portion used a composition comprising Supra 502, unlike Example 1.

[0154] <Comparative Example 2>

[0155] Unit cells were manufactured in the same manner as Example 1, except that no second adhesive portion was formed between the upper and lower separators, unlike Example 1.

[0156] <Comparative Example 3>

[0157] Unit cells were manufactured in the same manner as Example 1, except that the first adhesive portion used a composition comprising 2802 dispomelt, and no second adhesive portion was formed between the upper and lower separators, unlike Example 1.

[0158] <Comparative Example 4>

[0159] Unit cells were manufactured in the same manner as Example 1, except that the second adhesive portion used a composition comprising Supra 502, and no first adhesive portion was formed between the separator and the anode, and between the separator and the cathode, unlike Example 1.

[0160] <Comparative Example 5>

[0161] Unit cells were manufactured in the same manner as in Example 1, except that, unlike in Example 1, the second adhesive portion used a composition including 2802 dispomelt, and no first adhesive portion was formed between the separator and the anode and between the separator and the cathode.

[0162] <Experimental Example 2 - Measurement of electrode misalignment and adhesive portion thickness>

[0163] For the unit cells manufactured in Examples 1 to 4 and Comparative Examples 1 to 5, electrode misalignment was measured at 170 kV, 200 umA, and 34 W using a computed tomography (CT) scanner of GE Company at a resolution of 33 um / pixel. The results are shown in Table 2 below.

[0164] Further, for the unit cells manufactured in Examples 1 to 4 and Comparative Examples 1 to 5, the thickness of the first adhesive portion and / or the second adhesive portion was measured after being pressed by a pressure roller in the vertical direction and the both side direction of the unit cell. The results are shown in Table 2 below.

[0165] [Table 2]

[0166]

[0167] <Analysis of experimental results>

[0168] Referring to Tables 1 and 2, when a composition including acResin 204UV, Lotite EA608, and Technomelt 4046 was used for the first adhesive portion as in Examples 1 to 4, it was confirmed that no problem of electrode misalignment occurred, the thickness of the first adhesive portion was 5% or less with respect to the thickness of the electrode (200 um), and the thickness of the second adhesive portion was substantially equal to or less than the thickness of the electrode (200 um). In particular, it was confirmed that, in the case of Example 1, unlike in Examples 2 to 4, the second adhesive portion used a composition including acResin 204UV, and thus both the first adhesive portion and the second adhesive portion had excellent adhesive strength.

[0169] Unlike this, when a composition including Supra 502 was used for the first adhesive portion in Comparative Example 1, it was confirmed that the thickness of the first adhesive portion was 25% to 30% or less with respect to the thickness of the electrode (200 um), and the thickness of the first adhesive portion appeared to be too large, unlike in Examples 1 and 2.

[0170] This can confirm that, in the case of Supra 502 used in Comparative Example 1, the shear strength and viscosity are greater than those of acResin 204UV, Lotite EA608, and Technomelt 4046 used in Examples 1 to 4, and the thickness of the first adhesive portion appears to be greater than that of Examples 1 to 4. In addition, the same explanation can apply to the cases of 2802dispomelt, HPX 002, and EH9702, which have a higher shear strength than Supra 502.

[0171] Therefore, when the first adhesive portion includes at least one of an acrylic-based, EVA-based, and epoxy-based material, such as acResin 204UV, Lotite EA608, and Technomelt 4046, the thickness of the first adhesive portion can be very small compared to the thickness of the electrode (200 μm) without causing a problem of misalignment of the electrode.

[0172] In addition, in the case of the second adhesive portion, even if it includes acResin 204UV or Supra 502 as in Examples 1 to 4 and Comparative Example 1, it can be confirmed that the thickness of the second adhesive portion is substantially equal to or less than the thickness of the electrode (200 μm) without causing a problem of misalignment of the electrode. That is, it can be confirmed that the thickness of the second adhesive portion is almost similar in the measurement result after pressing regardless of the shear strength and viscosity of the ingredients.

[0173] Therefore, the second adhesive ingredient can include at least one of an acrylic-based, EVA-based, epoxy-based, polyolefin-based, rubber-based, polyamide-based, and polyurethane-based material, such as acResin 204UV, Lotite EA608, Technomelt 4046, Supra 502, 2802dispomelt, HPX 002, and EH9702.

[0174] However, if the shear strength or viscosity of the second adhesive portion is small, when the second adhesive portion is placed for a long time in the process, there can be a phenomenon in which a part of the second adhesive portion comes into contact with the electrode or leaks out of the end of the separator.

[0175] Therefore, it can be more preferable that the second adhesive portion include at least one of a polyolefin-based, rubber-based, polyamide-based, and polyurethane-based material, such as Supra 502, 2802dispomelt, HPX 002, and EH9702, as in Examples 2 to 4.

[0176] In addition, it can be confirmed that, when only the first adhesive portion is positioned in the unit cell as in Comparative Examples 2 and 3, the thickness of the first adhesive portion of Comparative Example 2 is the same as that of Examples 1 and 2, unlike Comparative Example 3. However, in Comparative Examples 2 and 3, no adhesive layer is formed between the upper and lower separators, and thus a problem in which the separators are folded in an additional process can occur, and the defect rate of the electrode can increase.

[0177] In addition, it can be confirmed that, when only the second adhesive portion is positioned in the unit cell as in Comparative Examples 4 and 5, all the thicknesses of the second adhesive portions are similar to those of Comparative Examples 1 to 4. However, no adhesive layer is formed between the separators and the cathode and between the separators and the anode, and thus a problem in which the electrodes are misaligned can occur, and the defect rate of the electrode can increase.

[0178] Therefore, unlike Comparative Examples 2 to 5, Examples 1 to 4 include the first adhesive portion and the second adhesive portion in the unit cell, and thus the first adhesive portion and the second adhesive portion can prevent movement between the electrodes and the separators and between the separators, and unlike the conventional lamination process, deformation and breakage of the electrodes and the separators can be prevented.

[0179] Figure 8 FIG. 1 is a cross-sectional view illustrating an electrode assembly according to one embodiment of the disclosure.

[0180] Referring to Figure 9 The electrode assembly 3 according to the present embodiment can include an electrode stack 40 manufactured by repeatedly forming a basic unit 30 a plurality of times. Here, the basic unit 30 can be a unit in which a separator 322 is folded to have a zigzag shape, covers an electrode 31, and the electrode 31 and the separator 322 are stacked. That is, in the basic unit 30, one side and the other side of the separator 322 are sequentially folded to cover the electrode 31, and the electrode 31 and the separator 322 can be sequentially stacked.

[0181] The fixing tape can be attached to the electrode assembly 3, but one end of the separator 322 can cover a portion of the outer surface of the electrode stack 40, rather than a portion of the outer surface of the fixing tape. The basic unit 30 of the present embodiment can be in a state in which the electrodes 3112 and 3122 and the separator 322 are adhered to each other with the adhesive 34. Therefore, the alignment between the electrodes 3112 and 3122 and the separator 322 can be maintained by the adhesion force of the adhesive 34.

[0182] In the electrode stack 40 of the present embodiment, the separator 322 covers the upper and lower portions and one side of the electrodes 3112 and 3122, and thus the stacking alignment of the unit cells 30 can be maintained without the fixing tape. Further, when the fixing tape is attached to the outside of the electrode stack 40 of the present embodiment or the separator 322 is wound with the fixing tape at one end thereof, the stacking alignment of the unit cells 30 is more stably maintained.

[0183] In addition, in the electrode assembly 3 manufactured in the present embodiment, the adhesive 34 can be disposed at the same position between the electrodes 3112 and 3122 and the separator 322. For example, as shown in FIG. 6A, in the electrode assembly 3 of the present embodiment, the adhesive 34 positioned between the lower portion of the first electrode 3112 and the separator 322 and the adhesive 34 positioned between the upper portion of the first electrode 3112 and the separator 322 can be disposed on the same vertical line with respect to the bottom surface of the first electrode 3112 or the separator 322, respectively, and the gaps for disposing the adhesives 34 can be equal to each other. This can be similarly explained in the case where the adhesive 34 is positioned between the second electrode 3122 and the separator 322. Figure 9

[0184] Thus, in the electrode assembly 3 manufactured in the present embodiment, the adhesive 34 is disposed at the same position between the electrodes 3112 and 3122 and the separator 322, and thus there is an advantage in that the process time and efficiency can be improved.

[0185] Figure 9 FIG. 7 is a cross-sectional view illustrating an electrode assembly according to another embodiment of the present disclosure.

[0186] Referring to FIG. 7, Figure 8 In the electrode assembly 4 according to the present embodiment, the adhesive 34 is disposed between the electrodes 3112 and 3122 and the separator 322, and the adhesives 34 disposed at adjacent layers can be disposed in a staggered form. For example, as shown in FIG. 7A, in the electrode assembly 4 of the present embodiment, the first adhesive 34-1 positioned between the lower portion of the first electrode 3112 and the separator 322 and the second adhesive 34-2 positioned between the upper portion of the first electrode 3112 and the separator 322 can be disposed to be offset from each other. In this case, the first adhesive 34-1 and the second adhesive 34-2 can be disposed to be offset from each other, and can be applied at the same distance. This can be similarly explained in the case where the adhesive 34 is positioned between the second electrode 3122 and the separator 322. Figure 9 However, the present application is not limited thereto, and the structure in which the first adhesive 34-1 and the second adhesive 34-2 are displaced from each other can be manufactured by applying various methods.

[0187]

[0188] ​​Accordingly, in the electrode assembly 4 of the present embodiment, the binder 34 is disposed between the electrodes 3112 and 3122 and the separator 322, and the binders 34 of adjacent layers are staggered. Accordingly, the increase in the thickness of the electrode assembly 4 due to the binder 34 can be minimized. Further, since the binders 34 disposed in adjacent layers are displaced from each other, the binder 34 can be more easily dissolved in the electrolyte included in the above-described battery cell.

[0189] The first binder component included in the first binder portion 310 can be used as the binder 34 used in the electrode assemblies 3 and 4 according to ​ and ​ .

[0190] While the present application has been shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and details can be made therein without departing from the spirit and scope of the application as defined by the appended claims.

[0191] [Legend of Reference Numerals]

[0192] 100: unit cell

[0193] 110: first electrode

[0194] 150: second electrode

[0195] 210: lower separator

[0196] 250: upper separator

[0197] 310: first binder portion

[0198] 350: second binder portion

[0199] 510, 520: pressure roller

[0200] 600: coating device

[0201] 1000: battery cell

[0202] 1100: electrode assembly

[0203] 2000: battery case

[0204] 3000: electrode lead

[0205] 4000: lead film

Claims

1. A cell unit, the cell unit comprising: A diaphragm and an electrode, wherein the diaphragm and the electrode are stacked alternately in a predetermined number; A first adhesive portion is located at an interface defined between the diaphragm and the electrode, thereby adhering the diaphragm and the electrode to each other at the interface, and the first adhesive portion comprises a first adhesive component, the first adhesive portion being disposed at a plurality of discrete locations spaced apart from each other at the interface; as well as The second adhesive portion, positioned between the diaphragm and another diaphragm, contains a second adhesive component. Wherein, the shear strength of the first adhesive portion is equal to or less than the shear strength of the second adhesive portion.

2. The cell according to claim 1, wherein, The shear strength of the first adhesive portion is 0.15 MPa or more and 0.5 MPa or less, and The shear strength of the second adhesive portion is above 0.15 MPa and below 3.5 MPa.

3. The cell according to claim 1, wherein, The shear strength of the second adhesive portion is above 1.5 MPa and below 3.5 MPa.

4. The cell according to claim 1, wherein, The viscosity of the first adhesive portion is equal to or less than the viscosity of the second adhesive portion.

5. The cell according to claim 4, wherein, The viscosity of the first adhesive portion is above 50 cP at 150°C to below 120 cP at 150°C, and The viscosity of the second adhesive portion is above 50 cP at 150°C to below 12000 cP at 150°C.

6. The cell according to claim 5, wherein, The viscosity of the second adhesive portion is above 800 cP at 150°C and below 12000 cP at 150°C.

7. The cell according to claim 1, wherein, The thickness of the first adhesive portion is less than the thickness of the electrode, and The thickness of the second adhesive portion is equal to or less than the thickness of the electrode.

8. The cell according to claim 7, wherein, The thickness of the first adhesive portion is more than 0.01% and less than 10% relative to the thickness of the electrode, and The thickness of the second adhesive portion is more than 90% and less than 100% of the thickness of the electrode.

9. The cell according to claim 1, wherein, The adhesive strength of the first adhesive portion is equal to or greater than the adhesive strength of the second adhesive portion.

10. The cell according to claim 9, wherein, The adhesive strength of the first adhesive portion is 50 gf / mm. 2 Up to 100gf / mm 2 Below, and The adhesive strength of the second adhesive portion is 20 gf / mm. 2 Up to 100gf / mm 2 the following.

11. The cell according to claim 1, wherein, The second adhesive portion is positioned between the end of the diaphragm and the end of the electrode.

12. The cell according to claim 11, wherein, The width of the second adhesive portion is less than the distance between the end of the diaphragm and the end of the electrode.

13. The cell according to claim 11, wherein, The first adhesive portion and the second adhesive portion are each formed as a pattern comprising a plurality of dots spaced apart from each other.

14. The cell according to claim 13, wherein, The diameter of the plurality of points contained in the second adhesive portion is smaller than the distance between the end of the electrode and the end of the diaphragm.

15. The cell according to claim 1, wherein, The first adhesive component comprises at least one of ethylene-vinyl acetate (EVA) based materials, acrylic based materials, and epoxy-based materials, and The second adhesive component comprises at least one of 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.

16. The cell according to claim 15, wherein, The second adhesive component comprises at least one of polyolefin-based materials, rubber-based materials, polyamide-based materials, and polyurethane-based materials.

17. An electrode assembly formed by alternately stacking cell cells according to any one of claims 1 to 16, the electrode assembly being configured such that: The first adhesive portion includes an adhesive pattern disposed at the same location between each of the electrodes and the diaphragm.

18. An electrode assembly formed by alternately stacking cell cells according to any one of claims 1 to 16, the electrode assembly being configured such that: The first adhesive portion includes an adhesive pattern arranged in an alternating pattern between each of the electrodes and the diaphragm.

19. A battery cell comprising an electrolyte solution and an electrode assembly, wherein cell units according to any one of claims 1 to 16 are alternately stacked in the electrode assembly.

20. The battery cell according to claim 19, wherein, The first adhesive portion has the property of dissolving in the electrolyte.

21. The battery cell according to claim 19, wherein, The diaphragm is folded into a zigzag shape.

22. A method for manufacturing a cell, the method comprising the following steps: The first adhesive is applied to the first surface of the electrode or to the adjacent area of ​​the first diaphragm, or both. The first adhesive is applied to the second side of the electrode or to the adjacent region of the second diaphragm, or both, wherein the second side of the electrode is located on the opposite side of the first side of the electrode; The second adhesive is applied to the peripheral region of the first diaphragm, or to the peripheral region of the second diaphragm, or to both. as well as By stacking the electrodes between the first diaphragm and the second diaphragm such that the first face of the electrode is adjacent to the adjacent region of the first diaphragm and the second face of the electrode is adjacent to the adjacent region of the second diaphragm, at least a portion of the stack is formed. The stack is configured such that the peripheral region of each of the first and second diaphragms extends outward beyond the edge of the electrode, and the peripheral regions of each of the first and second diaphragms are opposite to each other without the electrode being inserted between them. Wherein, the shear strength of the first adhesive is less than or equal to the shear strength of the second adhesive, and The first adhesive is located at the interface defined between the first diaphragm and the electrode, thereby adhering the first diaphragm and the electrode to each other at the interface, and the first adhesive is disposed at a plurality of discrete locations spaced apart from each other at the interface.

23. The method according to claim 22, further comprising the following steps: The stack is compressed along a direction orthogonal to the first and second surfaces of the electrodes.

24. The method of claim 22, further comprising the following steps: The stack and electrolyte are placed in the battery casing.

25. The method according to claim 22, wherein, The peripheral region of each of the first and second diaphragms extends around the periphery of the respective first and second diaphragms, such that each peripheral region surrounds the adjacent region of the respective first and second diaphragms.

26. The method according to claim 22, wherein, The first adhesive has a shear strength greater than or equal to 0.15 MPa and less than or equal to 0.5 MPa, and The second adhesive has a shear strength greater than or equal to 0.15 MPa and less than or equal to 3.5 MPa.

27. The method according to claim 22, wherein, The second adhesive has a shear strength greater than or equal to 1.5 MPa and less than or equal to 3.5 MPa.

28. The method according to claim 22, wherein, The viscosity of the first adhesive is less than or equal to the viscosity of the second adhesive.

29. The method according to claim 28, wherein, The viscosity of the first adhesive is greater than or equal to 50 cP@150°C and less than or equal to 120 cP@150°C, and The viscosity of the second adhesive is greater than or equal to 50 cP@150℃ and less than or equal to 1200 cP@150℃.

30. The method according to claim 29, wherein, The viscosity of the second adhesive is greater than or equal to 800 cP@150℃ and less than or equal to 1200 cP@150℃.

31. The method according to claim 22, wherein, The thickness of the first adhesive is less than the thickness of the electrode, and The thickness of the second adhesive is less than or equal to the thickness of the electrode.

32. The method according to claim 31, wherein, The thickness of the first adhesive is greater than or equal to 0.01% and less than or equal to 10% of the thickness of the electrode, and The thickness of the second adhesive is greater than or equal to 90% of the thickness of the electrode and less than or equal to 100% of the thickness of the electrode.

33. The method according to claim 22, wherein, The adhesive strength of the first adhesive is greater than or equal to the adhesive strength of the second adhesive.

34. The method according to claim 33, wherein, The adhesive strength of the first adhesive is greater than or equal to 50 gf / mm. 2 And less than or equal to 100gf / mm 2 ,and The adhesive strength of the second adhesive is greater than or equal to 20 gf / mm. 2 And less than or equal to 100gf / mm 2 .

35. The method according to claim 22, wherein, The width of the second adhesive applied to the peripheral region of the first diaphragm or the second diaphragm is smaller than the width of the peripheral region to which the second adhesive is applied.

36. The method according to claim 22, wherein, The first adhesive and the second adhesive are each applied in a corresponding dot pattern, the dot patterns being spaced apart from each other.

37. The method of claim 36, wherein, The diameter of each dot in the dot pattern of the second adhesive is smaller than the width of the respective peripheral region of the first diaphragm or the second diaphragm.

38. The method according to claim 36, wherein, The dots in the dot pattern of the first adhesive are arranged in a grid of rows and columns.

39. The method according to claim 22, wherein, The first adhesive comprises at least one of ethylene-vinyl acetate (EVA) based materials, acrylic based materials, and epoxy-based materials, and The second adhesive comprises at least one of ethylene-vinyl acetate (EVA) based materials, acrylic and epoxy materials, polyolefin based materials, rubber based materials, polyamide based materials, and polyurethane based materials.

40. The method according to claim 39, wherein, The second adhesive comprises at least one of polyolefin-based materials, rubber-based materials, polyamide-based materials, and polyurethane-based materials.

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