Patent Description:
As technology development and demands for mobile devices increase, the demand for batteries as energy sources is rapidly increasing. In particular, a secondary battery has attracted considerable attention as an energy source for power-driven devices, such as an electric bicycle, an electric vehicle, and a hybrid electric vehicle, as well as an energy source for mobile devices, such as a mobile phone, a digital camera, a laptop computer and a wearable device.

Based on the shape of a battery case, such a secondary battery may be classified into a cylindrical battery where an electrode assembly is mounted in a cylindrical metal can, a prismatic battery where an electrode assembly is mounted in a prismatic metal can, and a pouch-type battery where an electrode assembly is mounted in a pouch type case formed of an aluminum laminate sheet. Here, the electrode assembly mounted in the battery case is a power generating element, having a structure including a cathode, an anode, and a separator interposed between the cathode and the anode, and capable of being charged and discharged. The electrode assembly may be classified as a jelly-roll type electrode assembly configured to have a structure in which a long sheet-type cathode and a long sheet-type anode, which are coated with active materials, are wound in a state where 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 separators are interposed between the cathodes and the anodes. <CIT> discloses a jelly-roll electrode assembly comprising: a sheet-type positive electrode; a sheet-type negative electrode; and a separation membrane interposed between the positive electrode and the negative electrode, having a first adhesive coating unit and a second adhesive coating unit formed on a first surface of a sheet-type porous substrate, and having a third adhesive coating unit formed on a second surface facing the first surface.

Among them, particularly, a pouch-type battery, having a structure in which a stacked/folded type electrode assembly is mounted in a pouch-type battery case formed of an aluminum laminate sheet, has advantages such as low manufacturing costs, small weight, and easy shape deformation, and therefore, its usage is gradually increasing.

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

However, after being alternately stacked in the order of separator-anode-separator-cathode, a part of the separator or electrode is pushed out in place before entering the stacking device or during the progress of stacking, which causes problems that a breakage occurs or a difference in adhesive strength occurs.

Therefore, there is a need to develop a unit cell capable of preventing movement between the electrode and the separator and preventing deformation and breakage of the electrode and the separator.

It is an object of the present disclosure to provide a unit cell configured to adhere an electrode and a separator as well as a separator and a separator using an adhesive composition instead of a conventional lamination using heat and pressure, and a battery cell including the same.

The objects of the present disclosure are not limited to the aforementioned objects, and other objects which are not described herein should be clearly understood by those skilled in the art from the following detailed description and the accompanying drawings.

According to an embodiment of the present disclosure, there is provided a unit cell comprising: a separator and an electrode that are alternately stacked by a predetermined number; a first adhesive part that is positioned between the separator and the electrode and is composed of a first adhesive composition; and a second adhesive part that is positioned between the separator and the other separator and is composed of a second adhesive composition, wherein a shear strength of the first adhesive part is equal to or smaller than a shear strength of the second adhesive part.

The shear strength of the first adhesive part may be <NUM> MPa or more and <NUM> MPa or less, and the shear strength of the second adhesive part may be <NUM> MPa or more and <NUM> MPa or less.

The shear strength of the second adhesive part may be <NUM> MPa or more and <NUM> MPa or less.

A viscosity of the first adhesive part may be equal to or smaller than a viscosity of the second adhesive part.

The viscosity of the first adhesive part may be from 50cP@ <NUM> or more to 120cP@ <NUM> or less, and the viscosity of the second adhesive part may be from 50cP@ <NUM> or more to 12000cP@ <NUM> or less.

The viscosity of the second adhesive part may be from 800cP@ <NUM> or more to 12000cP@ <NUM> or less.

A thickness of the first adhesive part may be smaller than a thickness of the electrode, and a thickness of the second adhesive part may be equal to or smaller than thickness of the electrode.

The thickness of the first adhesive part may be from <NUM>% or more to <NUM>% or less relative to the thickness of the electrode, and the thickness of the second adhesive part may be from <NUM>% or more to <NUM>% or less relative to the thickness of the electrode.

An adhesive strength of the first adhesive part may be equal to or larger than an adhesive strength of the second adhesive part.

The adhesive strength of the first adhesive part may be from <NUM> gf/mm<NUM> or more to <NUM> gf/mm<NUM> or less, and the adhesive strength of the second adhesive part may be from <NUM> gf/mm<NUM> or more to <NUM> gf/mm<NUM> or less.

The second adhesive part may be positioned between an end part of the separator and an end part of the electrode.

A width of the second adhesive part may be smaller than a distance between an end part of the separator and an end part of the electrode.

The first adhesive part and the second adhesive part may be each formed in a pattern including a plurality of dots which are spaced apart from each other.

The plurality of dots contained in the second adhesive part may have a diameter smaller than a distance between the end part of the electrode and the end part of the separator.

The first adhesive composition may be composed 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 composed 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.

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

According to another embodiment of the present disclosure, there is provided an electrode assembly formed by alternately stacking the unit cell, the first adhesive part includes an adhesive pattern disposed at the same position between the electrode and the separator.

According to another embodiment of the present disclosure, there is provided an electrode assembly formed by alternately stacking the unit cell, the first adhesive part includes an adhesive pattern disposed at a staggered form between the electrode and the separator.

According to another embodiment of the present disclosure, there is provided a battery cell comprising an electrolyte solution together with an electrode assembly in which the unit cells are alternately stacked.

The first adhesive part may have a property of being dissolved in an electrolyte.

The battery cell may have a zigzag shape by folding the separator.

According to another embodiment of the present disclosure, there is provided a method of fabricating a unit cell, comprising: applying a first adhesive to either or both of (i) a first face of an electrode or (ii) an abutment region of a first separator; applying the first adhesive to either or both of (i) a second face of the electrode or (ii) an abutment region of a second separator, the second face of the electrode being on an opposite side of the electrode from the first face; applying a second adhesive to either or both of (i) a peripheral region of the first separator or (ii) a peripheral region of the second separator; 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 abuts the abutment region of the first separator and the second face of the electrode abuts the abutment region of the second separator, the stack being formed such the peripheral region of each of the first and second separators extends outwardly beyond an edge of the electrode, the peripheral regions of each of the first and second separators opposing one another 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.

The method of fabricating a unit cell may further comprise compressing the stack along a direction orthogonal to the first and second faces of the electrode.

The method of fabricating a unit cell may further comprise positioning the stack and an electrolyte in a battery case.

The peripheral region of each of the first and second separators may extend around the perimeter of the respective first and second separator, such that each of the peripheral regions encircles the abutment region of the respective first and second separator.

The shear strength of the first adhesive may be greater than or equal to <NUM> MPa and less than or equal to <NUM> MPa, and the shear strength of the second adhesive is greater than or equal to <NUM> MPa and less than or equal to <NUM> MPa.

The shear strength of the second adhesive may be greater than or equal to <NUM> MPa and less than or equal to <NUM> MPa.

A viscosity of the first adhesive may be less than or equal to a viscosity of the second adhesive.

The viscosity of the first adhesive may be greater than or equal to <NUM> cP at <NUM> and less than or equal to <NUM> cP at <NUM>, and the viscosity of the second adhesive is greater than or equal to <NUM> cP at <NUM> and less than or equal to <NUM> cP at <NUM>.

The viscosity of the second adhesive may be greater than or equal to <NUM> cP at <NUM> and less than or equal to <NUM> cP at <NUM>.

A thickness of the first adhesive may be smaller than a thickness of the electrode, and a thickness of the second adhesive is smaller than or equal to the thickness of the electrode.

The thickness of the first adhesive may be greater than or equal to <NUM>% of the thickness of the electrode and less than or equal to <NUM>% of the thickness of the electrode, and the thickness of the second adhesive is greater than or equal to <NUM>% of the thickness of the electrode and less than or equal to <NUM>% of the thickness of the electrode.

An adhesive strength of the first adhesive may be greater than or equal to an adhesive strength of the second adhesive.

The adhesive strength of the first adhesive may be greater than or equal to <NUM> gf/mm<NUM> and less than or equal to <NUM> gf/mm<NUM>, and the adhesive strength of the second adhesive is greater than or equal to <NUM> gf/mm<NUM> and less than or equal to <NUM> gf/mm<NUM>.

A width of the second adhesive applied to the peripheral region of either the first or second separator may be less than a width of the peripheral region to which the second adhesive is applied.

The first adhesive and the second adhesive may be each applied in a respective pattern of dots spaced apart from each other.

Each of the dots in the pattern of dots of the second adhesive may have a diameter smaller than a width of the peripheral region.

The dots in the pattern of dots of the first adhesive may be arranged in a grid of rows and columns of dots.

The first adhesive may be composed 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 composed 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.

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

According to the embodiments, the unit cell of the present disclosure and the battery cell including the same are configured to adhere an electrode and a separator as well as a separator and a separator using an adhesive composition instead of a 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.

Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement them. The disclosed embodiments may be modified in various different ways, without departing the sprit or scope of the present disclosure.

Portions that are irrelevant to the description will be omitted to clearly describe the present disclosure, and like reference numerals designate like elements throughout the specification.

Further, the size and thickness of each element are arbitrarily illustrated in the drawings for convenience of the description, and the present disclosure is not necessarily limited to those illustrated in the drawings. In the drawings, the thicknesses of some layers and regions are shown to be exaggerated for convenience of the description.

Further, throughout the specification, when a portion is referred to as "including" a certain component, it means that the portion includes stated components but not excludes any other components, unless explicitly described to the contrary.

Further, throughout the specification, when referred to as "planar", it means when a target portion is viewed from the upper side, and when referred to as "cross-sectional", it means when a target portion is viewed from the side of a cross section cut vertically.

Hereinafter, a unit cell according to an embodiment of the present disclosure will be described.

<FIG> is an exploded perspective view of a unit cell according to an embodiment of the present disclosure. <FIG> is a perspective view showing a unit cell in which the components of <FIG> are combined. <FIG> is a cross-sectional view taken along the A-A axis of <FIG>.

Referring to <FIG> and <FIG>, a unit cell according to an embodiment of the present disclosure includes: separators <NUM> and <NUM> and electrodes <NUM> and <NUM> that are alternately stacked by a predetermined number; a first adhesive part <NUM> that is positioned between the separators <NUM> and <NUM> and the electrodes <NUM> and <NUM> and is composed of a first adhesive composition; and a second adhesive part <NUM> that is positioned between separators <NUM> and <NUM> and the other separators <NUM> and <NUM> and is composed of a second adhesive composition.

More specifically, the separators <NUM> and <NUM> include a lower separator <NUM> and an upper separator <NUM>, and the electrodes <NUM> and <NUM> include a first electrode <NUM> and a second electrode <NUM>, wherein the lower separator <NUM>, the first electrode <NUM>, the upper separator <NUM> and the second electrode <NUM> may be stacked in this order.

Here, the first electrode <NUM> may include a first electrode tab <NUM> protruding in one direction, and the second electrode <NUM> may include a second electrode tab <NUM> protruding in one direction. In one example, as shown in <FIG> and <FIG>, the stacking may be performed such that the upper separator <NUM> is positioned between the first electrode <NUM> and the second electrode <NUM>, and the stacking may be performed such that the first electrode tab <NUM> of the first electrode <NUM> and the second electrode tab <NUM> of the second electrode <NUM> are positioned in opposite directions to each other. However, the present disclosure is not limited thereto, and a structure in which the first electrode tab <NUM> and the second electrode tab <NUM> are stacked so as to be positioned in the same direction may also be included in the embodiment of the disclosure.

Here, the first electrode <NUM> and the second electrode <NUM> may each include an electrode current collector and an active material layer positioned on the electrode current collector. Here, the active material layer may be formed of an electrode composition containing an electrode active material. More specifically, the first electrode <NUM> and the second electrode <NUM> may be a cathode and an anode. Here, the cathode may include a cathode current collector and an active material layer containing the cathode active material, and the anode may include an anode current collector and an active material layer containing the anode active material. In one example, the first electrode <NUM> may be an anode, and the second electrode <NUM> may be a cathode, but the present disclosure is not limited thereto, and vice versa may be included in the embodiment of the disclosure as well.

As the anode active material, an anode active material for a lithium secondary battery well-known in the art may be used, and as an example, a material such as lithium metal, lithium alloy, petroleum coke, activated carbon, graphite, silicon, tin, metal oxide or other carbons may be used.

In addition, in one example, the cathode active material may be selected from the group consisting of lithium-cobalt based oxide, lithium-manganese based oxide, lithium-nickel-manganese based oxide, lithium-manganese-cobalt based oxide, lithium-nickel-manganese-cobalt based oxide, and lithium iron phosphate, or may be a combination thereof or a composite oxide thereof.

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

The separators <NUM> and <NUM> may separate the first electrode <NUM> and the second electrode <NUM> and provide a moving passage of lithium ion. In addition, the separators <NUM> and <NUM> include a lower separator <NUM> and an upper separator <NUM>, and separators made of the materials which are different from or equal to each other can be applied as the lower separator <NUM> and the upper separator <NUM>.

In one example, the separators <NUM> and <NUM> can be used without particular limitation as long as they are normally used as separators in a lithium secondary battery. In particular, it is desirable that the separator has low resistance to ion movement of an electrolyte solution and is excellent in an electrolyte solution humidifying ability. Specifically, porous polymer films made of polyolefin-based polymers such as ethylene homopolymer, propylene homopolymer, ethylene/butene copolymer, ethylene/hexene copolymer and ethylene/methacrylate copolymer may be used alone, or a stacked structure having two or more layers thereof may be used.

Hereinafter, the first adhesive part <NUM> and the second adhesive part <NUM> included in the unit cell according to the embodiment of the disclosure are mainly described.

Referring to <FIG> and <FIG>, the first adhesive part <NUM> may be positioned at least one selected from between the first electrode <NUM> and the lower separator <NUM>, between the first electrode <NUM> and the upper separator <NUM>, and between the second electrode <NUM> and the upper separator <NUM>.

The first adhesive part <NUM> may be composed of a first adhesive composition, and the second adhesive part <NUM> may be composed of a second adhesive composition. In one example, the first adhesive composition may be composed 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 composed 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. More preferably, the second adhesive composition may be composed of at least one of a polyolefin-based material, a rubber-based material, a polyamide-based material and a polyurethane-based material, among the above-mentioned materials.

Therefore, the first adhesive part <NUM> can fix the first electrode <NUM> and the second electrode <NUM> to the lower separator <NUM> and/or the upper separator <NUM>, respectively. That is, unlike a conventional lamination process, the first adhesive part <NUM> can prevent movement between the electrodes <NUM> and <NUM> and the separators <NUM> and <NUM>, and prevent deformation and breakage of the electrodes <NUM> and <NUM> and the separators <NUM> and <NUM>.

Referring to <FIG> and <FIG>, the first adhesive part <NUM> and the second adhesive part <NUM> can have mutually different physical properties and physical conditions because the positions where they are formed are different from each other.

The shear strength of the first adhesive part <NUM> may be equal to or smaller than the shear strength of the second adhesive part <NUM>. Here, the shear strength of the first adhesive part <NUM> may be <NUM> MPa or more and <NUM> MPa or less, and the shear strength of the second adhesive part <NUM> may be <NUM> MPa or more and <NUM> MPa or less.

In one example, the shear strength of the first adhesive part <NUM> and the shear strength of the second adhesive part <NUM> may be <NUM> MPa or more and <NUM> MPa or less. More specifically, the shear strength of the first adhesive part <NUM> and the shear strength of the second adhesive part <NUM> may be <NUM> MPa or more and <NUM> MPa or less.

Therefore, the first adhesive part <NUM> and the second adhesive part <NUM> have a shear strength in the above-mentioned range, so that the first adhesive part <NUM> and the second adhesive part <NUM> can be easily pressed by pressure rolls <NUM> and <NUM> (<FIG>), respectively.

Unlike the same, when the shear strength of the first adhesive part <NUM> and the second adhesive part <NUM> is less than <NUM> MPa, it may be disadvantageous to the adhesion and fixation between the electrodes <NUM> and <NUM> and the separators <NUM> and <NUM>. Further, when the shear strength of the first adhesive part <NUM> and the second adhesive part <NUM> exceeds <NUM> MPa, the first adhesive part <NUM> may not be easily pressed by the pressure rolls <NUM> and <NUM> (<FIG>) and thus, the first thickness d1 of the first adhesive part <NUM> may be excessively large or non-uniform.

In another example, the shear strength of the first adhesive part <NUM> may be <NUM> MPa or more and <NUM> MPa or less, and the shear strength of the second adhesive part <NUM> may be <NUM> MPa or more and <NUM> MPa or less. More specifically, the shear strength of the first adhesive part <NUM> may be <NUM> MPa or more and <NUM> MPa or less, and the shear strength of the second adhesive part <NUM> may be <NUM> MPa or more and <NUM> MPa or less.

Therefore, the second adhesive part <NUM> and the first adhesive part <NUM> have a shear strength in the above-mentioned range, and thus, the second adhesive part <NUM> and the first adhesive part <NUM> may be easily pressed by the pressure rolls <NUM> and <NUM> (<FIG>), respectively. Further, the shear strength of the second adhesive part <NUM> is larger than the shear strength of the first adhesive part <NUM> and thus, a phenomenon, in which a part of the second adhesive part <NUM> comes into contact with the electrodes <NUM> and <NUM> or leaks outside the end parts of the separators <NUM> and <NUM>, can be prevented in advance.

Unlike the same, when the shear strength of the second adhesive part <NUM> is less than <NUM> MPa, the second adhesive part <NUM> spreads out on both sides in some processes, which causes a problem that a part of the second adhesive part <NUM> comes in contact with the electrodes <NUM> and <NUM> or leaks outside the end parts of the separators <NUM> and <NUM>. Further, when the shear strength of the second adhesive part <NUM> exceeds <NUM> MPa, the second adhesive part <NUM> may not be easily pressed by the pressure rolls <NUM> and <NUM> (<FIG>) and thus, the second thickness d2 of the second adhesive part <NUM> may be excessively large or non-uniform.

Further, the first thickness d1 of the first adhesive part <NUM> may be smaller than the second thickness d2 of the second adhesive part <NUM>. More specifically, the first thickness d1 of the first adhesive part <NUM> is smaller than the thickness D1 of the electrodes <NUM> and <NUM>, and the second thickness d2 of the second adhesive part <NUM> may be equal to or larger than the thickness D1 of the electrodes <NUM> and <NUM>. In one example, as shown in <FIG>, the first thickness d1 of the first adhesive part <NUM> is smaller than the thickness d2 of the first electrode <NUM>, and the second thickness d2 of the second adhesive part <NUM> may be equal to or smaller than the thickness D1 of the first electrode <NUM>.

Therefore, the first adhesive part <NUM> has a relatively small thickness, and so can reduce a gap that may be generated between the electrodes <NUM> and <NUM> and the separators <NUM> and <NUM>, and improve a space efficiency of the unit cell <NUM>. Further, the second adhesive part <NUM> has a thickness similar to that of the first electrode <NUM> and thus, the thickness of the unit cell <NUM> may be relatively uniform while being easily adhered and fixed between the lower separator <NUM> and the upper separator <NUM>.

Further, the first thickness d1 of the first adhesive part <NUM> may be <NUM>% or more and <NUM>% or less relative to the thickness D1 of the electrodes <NUM> and <NUM>. More specifically, the first thickness d1 of the first adhesive part <NUM> may be <NUM>% or more and <NUM>% or less relative to the thickness D1 of the electrodes <NUM> and <NUM>. In one example, the first thickness d1 of the first adhesive part <NUM> may be <NUM>% or more and <NUM>% or less relative to the thickness D1 of the electrodes <NUM> and <NUM>.

Therefore, the first thickness d1 of the first adhesive part <NUM> has a ratio in the above-mentioned range relative to the thickness D1 of the electrodes <NUM> and <NUM> and thus, the thickness of the unit cell <NUM> may be relatively uniform while being easily adhered and fixed between the electrodes <NUM> and <NUM> and the separators <NUM> and <NUM>.

Unlike the same, when the first thickness d1 of the first adhesive part <NUM> is less than <NUM>% relative to the thickness D1 of the electrodes <NUM> and <NUM>, the fixing force between the electrodes <NUM> and <NUM> and the separators <NUM> and <NUM> is not sufficient, which causes a problem that the electrodes <NUM> and <NUM> and the separators <NUM> and <NUM> are detached from each other in a subsequent process. Further, when the first thickness d1 of the first adhesive part <NUM> is larger than <NUM>% of the thickness D1 of the electrodes <NUM> and <NUM>, the interval between the electrodes <NUM> and <NUM> and the separators <NUM> and <NUM> is too large, which causes a problem that the space efficiency and the battery capacity of the unit cell <NUM> are reduced.

<FIG> is a cross-sectional view showing a process in which the unit cell of <FIG> is pressed.

Further, referring to <FIG> and <FIG>, the first thickness d1 of the first adhesive part <NUM> and the second thickness d2 of the second adhesive part <NUM> may be the thickness after being pressed in the vertical and both side directions of the unit cell <NUM> by the pressure rolls <NUM> and <NUM>. Here, the pressure rolls <NUM> and <NUM> may be rolls such as nip rolls, and may press the unit cell <NUM> in the vertical and both side directions of the unit cell <NUM>.

Here, in the unit cell <NUM> before being pressed by the pressure rolls <NUM> and <NUM>, the third thickness d3 of the first adhesive part <NUM> may be larger than the first thickness d1 of the first adhesive part <NUM>. More specifically, the third thickness d3 of the first adhesive part <NUM> may be <NUM>% or more to <NUM>% or less relative to the thickness D1 of the electrodes <NUM> and <NUM>. In one example, the third thickness d3 of the first adhesive part <NUM> may be <NUM>% or more to <NUM>% or less relative to the thickness D1 of the electrodes <NUM> and <NUM>.

In addition, the fourth thickness d4 of the second adhesive part <NUM> may be larger than the second thickness d2. More specifically, the fourth thickness d4 of the second adhesive part <NUM> may be <NUM>% or more and <NUM>% or less relative to the thickness D1 of the electrodes <NUM> and <NUM>. In one example, the fourth thickness d4 of the second adhesive part <NUM> may be <NUM>% or more and <NUM>% or less relative to the thickness D1 of the electrodes <NUM> and <NUM>.

Therefore, the thickness of the first adhesive part <NUM> and the second adhesive part <NUM> before being pressed by the pressure rolls <NUM> and <NUM> may have a thickness ratio in the above-mentioned range, whereby even after the unit cell <NUM> is pressed by the pressure rolls <NUM> and <NUM>, the thickness of the unit cell <NUM> may be relatively uniform while being easily adhered and fixed between the separators <NUM> and <NUM> or between the electrodes <NUM> and <NUM> and the separators <NUM> and <NUM>.

Further, the adhesive strength of the first adhesive part <NUM> may be equal to or larger than that of the second adhesive part <NUM>. Here, the adhesive strength of the first adhesive part <NUM> and the second adhesive part <NUM> can be measured by applying the first adhesive composition and the second adhesive composition in the form of <NUM> dots at an interval of <NUM> between a pair of pre-prepared tension jigs, and then vertically peeling them.

At this time, the adhesive strength of the first adhesive part <NUM> may be form <NUM> gf/mm<NUM> or more to <NUM> gf/mm<NUM> or less, and the adhesive strength of the second adhesive part <NUM> may be from <NUM> gf/mm<NUM> or more to <NUM> gf/mm<NUM> or less. More specifically, the adhesive strength of the first adhesive part <NUM> may be <NUM> gf/mm<NUM> or more and <NUM> gf/mm<NUM> or less, and the adhesive strength of the second adhesive part <NUM> may be <NUM> gf/mm<NUM> or more and <NUM> gf/mm<NUM> or less. In one example, the adhesive strength of the first adhesive part <NUM> may be <NUM> gf/mm<NUM> or more and <NUM> gf/mm<NUM> or less, and the adhesive strength of the second adhesive part <NUM> may be <NUM> gf/mm<NUM> or more and <NUM> gf/mm<NUM> or less.

Therefore, the first adhesive part <NUM> and the second adhesive part <NUM> have an adhesive strength in the above-mentioned range and thus, the first adhesive part <NUM> and the second adhesive part <NUM> can each be easily adhered and fixed between the separators <NUM> and <NUM> or between the electrodes <NUM> and <NUM> and the separators <NUM> and <NUM>.

Unlike the same, when the adhesive strength of the first adhesive part <NUM> is less than <NUM> gf/mm<NUM> or more than <NUM> gf/mm<NUM>, there is a problem that the electrodes <NUM> and <NUM> and the separators <NUM> and <NUM> are detached from each other in a subsequent process, or the manufacturing process is difficult. In addition, when the adhesive strength of the second adhesive part <NUM> is less than <NUM> gf/mm<NUM> or more than <NUM> gf/mm<NUM>, there is a problem that the upper separator <NUM> and the lower separator <NUM> are detached from each other in a subsequent process, or the manufacturing process is difficult.

<FIG> is a diagram showing a process in which a first adhesive part and a second adhesive part included in the unit cell of <FIG> are applied.

Further, the viscosity of the first adhesive part <NUM> may be equal to or smaller than the viscosity of the second adhesive part <NUM>. More specifically, referring to <FIG> and <FIG>, the first adhesive part <NUM> and the second adhesive part <NUM> may be applied to the electrodes <NUM> and <NUM> and/or the separators <NUM> and <NUM> by a coating device <NUM>. In one example, the coating device <NUM> may be a device such as an inkjet spraying device, and the coating device <NUM> may include a housing <NUM> that causes a change in the volume of an internal pressure chamber, a wall surface <NUM> that reduces the volume of the pressure chamber, and an outlet port 610a through which the adhesive composition is discharged. That is, the viscosity of the first adhesive part <NUM> and the second adhesive part <NUM> may be a discharge viscosity discharged from the outlet port 610a of the coating device <NUM>.

More specifically, the viscosity of the first adhesive part <NUM> and the second adhesive part <NUM> may be a viscosity (cP@ <NUM>) discharged from the outlet port 610a of the coating device <NUM> at <NUM> degrees Celsius. Here, the viscosity of the first adhesive part <NUM> may be from 50cP@ <NUM> or more to 120cP@ <NUM> or less, and the viscosity of the second adhesive part <NUM> may be from 50cP@ <NUM> or more to 12000cP@ <NUM> or less.

In one example, the viscosity of the first adhesive part <NUM> and the viscosity of the second adhesive part <NUM> may be from 60cP@ <NUM> or more to 110cP@ <NUM> or less, respectively. More specifically, the viscosity of the first adhesive part <NUM> and the viscosity of the second adhesive part <NUM> may be 70cP@ <NUM> or more and 100cP@ <NUM> or less, respectively.

Therefore, the first adhesive part <NUM> and the second adhesive part <NUM> have a viscosity in the above-described range, whereby the first adhesive part <NUM> and the second adhesive part <NUM> each have an adhesive strength capable of easily adhering and fixing between the separators <NUM> and <NUM> or between the electrodes <NUM> and <NUM> and the separators <NUM> and <NUM>, respectively, and also the discharge stability of the coating device <NUM> may be improved.

Unlike the same, when the viscosity of the first adhesive part <NUM> and the second adhesive part <NUM> is less than 60cP@ <NUM>, it may be disadvantageous to the adhesion and fixation between the electrodes <NUM> and <NUM> and the separators <NUM> and <NUM>. In addition, when the viscosity of the first adhesive part <NUM> and the second adhesive part <NUM> exceeds 120cP@ <NUM>, the first adhesive part <NUM> may not be easily pressed by the pressure rolls <NUM> and <NUM> (<FIG>) and thus, the first thickness d1 of the first adhesive part <NUM> may be excessively large or non-uniform.

In another example, the viscosity of the first adhesive part <NUM> may be from 60cP@ <NUM> or more to 110cP@ <NUM> or less, and the viscosity of the second adhesive part <NUM> may be from 800cP@ <NUM> or more to 12000cP@ <NUM> or less. More specifically, the viscosity of the first adhesive part <NUM> may be from 70cP@ <NUM> or more to 100cP@ <NUM> or less, and the viscosity of the second adhesive part <NUM> may be from <NUM> cP@ <NUM> or more to 11000cP@ <NUM> or less.

Therefore, as the first adhesive part <NUM> and the second adhesive part <NUM> have a viscosity in the above-described range, the first adhesive part <NUM> and the second adhesive part <NUM> each have an adhesive strength capable of easily adhering and fixing between the separators <NUM> and <NUM> or between the electrodes <NUM> and <NUM> and the separators <NUM> and <NUM>, respectively, and also the discharge stability of the coating device <NUM> may be improved. In addition, as the viscosity of the second adhesive part <NUM> is larger than the viscosity of the first adhesive part <NUM>, a phenomenon, in which a part of the second adhesive part <NUM> comes into contact with the electrodes <NUM> and <NUM> or leaks outside the end parts of the separators <NUM> and <NUM>, can be prevented in advance.

Unlike the same, when the viscosity of the second adhesive part <NUM> is less than 800cP@ <NUM>, the second adhesive part <NUM> spreads out on both sides in some processes, which causes a problem that a part of the second adhesive part <NUM> is in contact with the electrodes <NUM> and <NUM> or leaks outside the end parts of the separators <NUM> and <NUM>. Further, when the viscosity of the second adhesive part <NUM> is larger than 12000cP@ <NUM>, there is a problem that the discharge stability of the coating device <NUM> is lowered.

Here, the first width r1 of the second adhesive part <NUM> may be smaller than the distance D2 between the end parts of the separators <NUM> and <NUM> and the end parts of the electrodes <NUM> and <NUM>. More specifically, the first width r1 of the second adhesive part <NUM> may be the width after being pressed in the vertical and both side directions of the unit cell <NUM> by the pressure rolls <NUM> and <NUM>. That is, the first width r1 of the second adhesive part <NUM> may be larger than the second width r2 of the second adhesive part <NUM> before being pressed by the pressure rolls <NUM> and <NUM>.

Therefore, the first width r1 of the second adhesive part <NUM> is smaller than the distance D2 between the end parts of the separators <NUM> and <NUM> and the end parts of the electrodes <NUM> and <NUM>, whereby even after the second adhesive part <NUM> is pressed by the pressure rolls <NUM> and <NUM>, a phenomenon, in which a part of the second adhesive part <NUM> comes into contact with the electrodes <NUM> and <NUM> or leaks outside the end parts of the separators <NUM> and <NUM>, can be prevented.

Further, the first adhesive part <NUM> and the second adhesive part <NUM> may be formed in a pattern including a plurality of dots which are spaced apart from each other, as shown in <FIG> and <FIG>. Here, the intervals between the plurality of dots may be adjusted to be the same or different from each other, if necessary.

Therefore, the first adhesive part <NUM> and the second adhesive part <NUM> can be formed in the pattern described above, whereby when the electrolyte solution is injected into the electrode assembly <NUM> (<FIG>) including the plurality of unit cells <NUM>, there is an advantage in that the electrode assembly <NUM> (<FIG>) can be rapidly impregnated. More specifically, since the plurality of dots are spaced apart from each other in the first adhesive part <NUM> and the second adhesive part <NUM>, there is an advantage in that the electrolyte solution may flow between the plurality of dots. That is, the manufacturing time of the battery cells <NUM> (<FIG>) can be relatively shortened, and the yield can also be improved.

The first adhesive part <NUM> may block a lithium ion passage between the electrodes <NUM> and <NUM> and the separators <NUM> and <NUM>. In order to prevent this, it may be preferable that the first adhesive part <NUM> is made of a material having a high solubility in an electrolyte solution.

According to an embodiment, the first adhesive part <NUM> and the second adhesive part <NUM> may include materials having mutually different compositions. In one example, the first adhesive composition forming the first adhesive part <NUM> may be composed 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 forming the second adhesive part <NUM> may be composed of 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 composition is made of an acrylic material, it may be considered to exhibit a certain amount of solubility in the electrolyte because the acrylic material includes an ester group.

Therefore, the first adhesive composition included in the first adhesive part <NUM> may be dissolved between the electrodes <NUM> and <NUM> and the separators <NUM> and <NUM>, when the electrolyte solution is injected into the electrode assembly <NUM> (<FIG>) including a plurality of unit cells <NUM>. That is, in this case, the first adhesive part <NUM> positioned between the electrodes <NUM> and <NUM> and the separators <NUM> and <NUM> is dissolved in the electrolyte solution, so that it may obstruct the lithium ion passage between the electrodes <NUM> and <NUM> and the separators <NUM> and <NUM>.

Referring to <FIG>, unlike the first adhesive composition included in the first adhesive part <NUM> corresponding to the first position, in the case of the second adhesive composition included in the second adhesive part <NUM> corresponding to the second position, it is confirmed that the oxidation reaction occurs around <NUM> V as a result according to Linear Sweep Voltammetry (LSV). This may cause a side reaction in the battery cell, which may be a factor in reducing capacity and lifespan. Therefore, it is not preferable to use the second adhesive composition for the first adhesive part <NUM>. One of the reasons for forming the second adhesive part <NUM> is to prevent folding of the separator caused during the electrolyte injection process.

The result as shown in <FIG> may appear when at least one of an ethylene-vinyl acetatebased material, an acrylic material, and an epoxy-based material is used as the first adhesive composition, and a polyolefin-based material, a rubber-based material, a polyamide-based material, and a polyurethane-based material are used as the second adhesive composition.

The separator according to the embodiment described herein may be a Ceramic Coated Separator (CCS). In general, the separator has a raw film and a coating layer formed on at least one surface of the raw film, and the coating layer may include alumina powder and a binder to aggregate them. In Safety Reinforced Separator (SRS), a large amount of binder is coated on the surface of the coating layer, but in CCS, the binder is not coated on the surface of the coating layer, or the binder content distributed on the surface may be very low compared to 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 may be about <NUM> wt% or less.

When the separator is CCS, since the internal electrodes included in the electrode assembly are transported in an unfixed state, alignment may be disturbed during transport. Of course, when the separator is CCS, it may be fixed by heat and pressure, but the alignment of the internal electrodes may be disturbed even in the process of transferring the electrode and the separator to the fixing device for heat and pressure after forming the laminate of the electrode and the separator. 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 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 electrodes from being disturbed during transport.

Here, the plurality of dots included in the second adhesive part <NUM> may have a diameter smaller than the distance D2 between the end parts of the electrodes <NUM> and <NUM> and the end parts of the separators <NUM> and <NUM>. Here, the diameter of the second adhesive part <NUM> can be explained in the same manner as in the widths r1 and r2 of the second adhesive part <NUM> described above.

<FIG> is a top view of a battery cell according to another embodiment of the present disclosure.

Referring to <FIG> and <FIG>, the battery cell <NUM> according to another embodiment of the present disclosure includes an electrolyte solution together with the electrode assembly <NUM> on which the above-mentioned unit cells <NUM> are alternately stacked. Here, first electrode tabs <NUM> on which the first electrode tabs <NUM> of the unit cell <NUM> are stacked, and second electrode tabs <NUM> on which the second electrode tabs <NUM> are stacked can be electrically connected to electrode leads <NUM>, respectively. Lead films <NUM> may be positioned above and/or below the electrode leads <NUM>.

Further, the electrode assembly <NUM> is mounted inside the battery case <NUM>, wherein the electrode assembly <NUM> may be positioned in the receiving part <NUM> having a concave shape together with the electrolyte solution. In addition, a sealing part <NUM> may be formed such that the outer peripheral surfaces of the battery case <NUM> are mutually heat-fused and sealed.

In one example, the electrolyte solution can be comprised of 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 or the like, but the present disclosure is not limited thereto, and all the electrolyte solutions commonly used in the art can be included.

Hereinafter, the content of the present disclosure will be described with reference to more specific examples, but the following examples are for illustrative purposes only, and the scope of rights of the present disclosure is not limited thereto.

The shear strength, viscosity, and adhesive strength were respectively measured for 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 as an adhesive composition.

Here, the acrylic-based material was acResin 204UV available from BASF, the EVA-based material was Technomelt <NUM> from Henkel, the epoxy-based material was Lotite EA608 from Henkel, the polyolefin-based material was Supra502 from Henkel, the rubber-based material was 2802dispomelt from Henkel, the polyamide-based material was HPX <NUM> from Henkel, and the polyurethane-based material was EH9702 from Fuller.

The shear strength was measured with a universal testing machine (UTM) in accordance with the ASTM D3163 standard.

The viscosity was measured under the condition of <NUM> rpm by replacing the spindle part of Brookfield DV2T LV TJ10 model machine with a cone and plate, and applying a CPA-40Z cone.

The adhesive strength was measured by applying one of the above-mentioned adhesive compositions in the form of <NUM> dots at an interval of <NUM> between a pair of pre-prepared tension jigs, and then peeling them vertically.

LiNi<NUM>Mn<NUM>Co<NUM>O<NUM> as a cathode active material, carbon black as a conductive material, and polyvinylidene fluoride (PVdF) as a binder were respectively used, and NMP as a solvent was added to a mixture of cathode active material: conductive material: binder in a weight ratio of <NUM>: <NUM>: <NUM> to prepare a cathode active material slurry. The cathode active material slurry was applied to an aluminum current collector, then dried and rolled to manufacture a cathode. Here, the thickness of the cathode was <NUM>.

An artificial graphite as an anode active material, carbon black as a conductive material, and SBR emulsion aqueous solution as a binder were respectively used, and water was added to a mixture of anode active material: conductive material: binder in a weight ratio of <NUM>: <NUM>: <NUM> to prepare an anode active material slurry. The anode active material slurry was applied to a copper current collector, then dried and rolled to manufacture an anode. Here, the thickness of the anode was <NUM>.

A slurry mixed with Al<NUM>O<NUM> and PVDF in a weight ratio of <NUM>:<NUM> was applied on both sides (each thickness: <NUM> µm) of a base sheet (thickness: <NUM> µm) made of polyethylene/polypropylene, and dried at <NUM> to manufacture a separator. The separator is referred to as an upper separator and a lower separator depending on the position.

The manufactured lower separator, anode, upper separator, and cathode was alternately stacked in this order to manufacture a unit cell in which a first adhesive part composed of acResin 204UV was positioned between the separator and the anode and between the separator and the anode, and a second adhesive part composed of acResin 204UV was positioned between the upper separator and the lower separator.

A unit cell was manufactured in the same manner as in Example <NUM>, except that in Example <NUM>, a composition composed of Supra502 was used for the second adhesive part.

A unit cell was manufactured in the same manner as in Example <NUM>, except that in Example <NUM>, a composition composed of Lotite EA608 was used for the first adhesive part and a composition composed of Supra502 was used for the second adhesive part.

A unit cell was manufactured in the same manner as in Example <NUM>, except that in Example <NUM>, a composition composed of Technomelt <NUM> was used for the first adhesive part, and a composition composed of Supra502 was used for the second adhesive part.

A unit cell was manufactured in the same manner as in Example <NUM>, except that in Example <NUM>, a composition composed of Supra502 was used for the first adhesive part.

A unit cell was manufactured in the same manner as in Example <NUM>, except that in Example <NUM>, the second adhesive part was not formed between the upper separator and the lower separator.

A unit cell was manufactured in the same manner as in Example <NUM>, except that in Example <NUM>, a composition composed of <NUM> dispomelt was used for the first adhesive part, and the second adhesive part was not formed between the upper separator and the lower separator.

A unit cell was manufactured in the same manner as in Example <NUM>, except that in Example <NUM>, a composition composed of Supra502 was used for the second adhesive part, and the first adhesive part was not formed between the separator and the anode and between the separator and the cathode.

A unit cell was manufactured in the same manner as in Example <NUM>, except that in Example <NUM>, a composition composed of <NUM> dispomelt was used for the second adhesive part, and a first adhesive part was not formed between the separator and the anode and between the separator and the cathode.

For the unit cells manufactured in Examples <NUM> to <NUM> and Comparative Examples <NUM> to <NUM>, the electrode misalignment was measured at a resolution of <NUM>/pixel under the conditions of 170kV, 200umA, and 34W by using Computed Tomography (CT) Scanner from GE.

In addition, for the unit cells manufactured in Examples <NUM> to <NUM> and Comparative Examples <NUM> to <NUM>, the thicknesses of the first adhesive part and/or the second adhesive part were respectively measured after being pressed in the vertical and both side directions of the unit cell by a pressure roll.

Referring to Table <NUM> and Table <NUM>, when a composition composed of acResin 204UV, Lotite EA608, and Technomelt <NUM> was used for the first adhesive part as in Examples <NUM> to <NUM>, it can be confirmed that the problem of electrode misalignment was not generated, the thickness of the first adhesive part was <NUM>% or less relative to the thickness (<NUM>) of the electrode, and the thickness of the second adhesive part was substantially equal to or smaller than the thickness (<NUM>) of the electrode. In particular, it can be confirmed that in the case of Example <NUM>, a composition composed of acResin 204UV was used for the second adhesive part unlike Examples <NUM> to <NUM> and thus, both the first adhesive part and the second adhesive part had excellent adhesive strength.

Unlike the same, when the composition composed of Supra502 was used for the first adhesive part as in Comparative Example <NUM>, it can be confirmed that the thickness of the first adhesive part is <NUM>% to <NUM>% or less relative to the thickness (<NUM>) of the electrode and the thickness of the first adhesive part appears excessively large, unlike Examples <NUM> and <NUM>.

This can be confirmed that in the case of Supra502 used in Comparative Example <NUM>, the shear strength and viscosity are larger than those of acResin 204UV, Lotite EA608, and Technomelt <NUM> used in Examples <NUM> to <NUM> and the thickness of the first adhesive part appears larger than that of Examples <NUM> to <NUM>. In addition, the same interpretation can be applied to the case of 2802dispomelt, HPX <NUM>, and EH9702, having higher shear strength than Supra502.

Therefore, when the first adhesive part is composed of at least one of acrylic-based, EVA-based, and epoxy-based materials such as acResin 204UV, Lotite EA608, and Technomelt <NUM>, the thickness of the first adhesive part can be very small compared to the thickness of the electrode (<NUM>) without generating the problem of electrode misalignment.

Further, in the case of the second adhesive part, even if it is composed of acResin 204UV or Supra502 as in Examples <NUM> to <NUM> and Comparative Example <NUM>, it can be confirmed that the thickness of the second adhesive part is substantially equal to or smaller than the thickness (<NUM>) of the electrode, without generating the problem of electrode misalignment. That is, it can be confirmed that the thickness of the second adhesive part is almost similarly measured after pressing, regardless of the shear strength and viscosity of the composition.

Therefore, the second adhesive composition can be composed of at least one of acrylic-based, EVA-based, epoxy-based, polyolefin-based, rubber-based, polyamide-based and polyurethane-based materials such as acResin 204UV, Lotite EA608, Technomelt <NUM>, Supra502, 2802dispomelt, HPX <NUM>, and EH9702.

However, if the shear strength or viscosity of the second adhesive part is small, a phenomenon can occur in which a part of the second adhesive part comes into contact with the electrode or leaks outside the end part of the separator, when the second adhesive part is left for a long time in the process.

Therefore, it may be more preferable that the second adhesive part is composed of at least one of polyolefin-based, rubber-based, polyamide-based, and polyurethane-based materials, such as Supra502, 2802dispomelt, HPX <NUM>, and EH9702, as in Examples <NUM> to <NUM>.

In addition, it can be confirmed that when only the first adhesive part is positioned in the unit cell as in Comparative Examples <NUM> and <NUM>, Comparative Example <NUM> has the same thickness as Examples <NUM> and <NUM> of the first adhesive part, unlike Comparative Example <NUM>. However, in Comparative Example <NUM> and Comparative Example <NUM>, an adhesive layer between the upper separator and the lower separator is not formed and thus, a problem may occur in which the separator is folded in an additional process, and the defective rate of the electrode may be increased.

In addition, it can be confirmed that when only the second adhesive part is positioned in the unit cell as in Comparative Examples <NUM> and <NUM>, all the thicknesses of the second adhesive parts are similar to those of Examples <NUM> to <NUM>. However, an adhesive layer between the separator and the cathode and between the separator and the anode is not formed, whereby the problem of electrode misalignment can be generated, and the defective rate of the electrode can be increased.

Therefore, unlike Comparative Examples <NUM> to <NUM>, Examples <NUM> to <NUM> include both the first adhesive part and the second adhesive part in the unit cell, whereby the first adhesive part and the second adhesive part can prevent movement between the electrode and the separator and between the separator and the separator, and unlike the conventional lamination process, it is possible to prevent deformation and breakage of the electrode and the separator.

<FIG> is a cross-sectional view showing an electrode assembly according to an embodiment of the present disclosure.

Referring to <FIG>, the electrode assembly <NUM> according to the present embodiment may include an electrode stack <NUM> manufactured by repeatedly forming the basic unit <NUM> a plurality of times. Here, the basic unit <NUM> may be a unit in which the separator <NUM> is folded to have a zigzag shape, covers the electrode <NUM>, and the electrode <NUM> and the separator <NUM> are stacked. That is, in the basic unit <NUM>, one side and the other side of the separator <NUM> are sequentially folded to cover the electrode <NUM>, and the electrode <NUM> and the separator <NUM> may be sequentially stacked.

A fixing tape may be attached to the electrode assembly <NUM>, but one end of the separator <NUM> may cover a portion of the outer surface of the electrode stack <NUM> instead of the fixing tape. The basic unit <NUM> of the present embodiment may be in a state in which the electrodes <NUM> and <NUM> and the separator <NUM> are adhered to each other with an adhesive <NUM>. Accordingly, the alignment between the electrodes <NUM> and <NUM> and the separator <NUM> may be maintained by the adhesive force of the adhesive <NUM>.

In the electrode stack <NUM> of this embodiment, the separator <NUM> covers the upper and lower portions and one side of the electrodes <NUM> and <NUM>, so that the stacking alignment of the basic units <NUM> can be maintained without the fixing tape. In addition, when the fixing tape is attached to the outside of the electrode stacked body <NUM> of this embodiment or one end of the separator <NUM> is wrapped around it, the stacking alignment of the basic units <NUM> is more stably maintained.

Also, in the electrode assembly <NUM> manufactured in this embodiment, the adhesive <NUM> may be disposed at the same position between the electrodes <NUM> and <NUM> and the separator <NUM>. For example, as shown in <FIG> , in the electrode assembly <NUM> of this embodiment, the adhesive <NUM> positioned between the lower portion of the first electrode <NUM> and the separator <NUM> and the adhesive <NUM> between the upper portion of the first electrode <NUM> and the separator <NUM> may be disposed on the same vertical line with respect to the bottom surface of the first electrode <NUM> or the separator <NUM>, respectively, and the gap at which the adhesive <NUM> is disposed may be equal to each other. This may be similarly explained in the case of the adhesive <NUM> positioned between the second electrode <NUM> and the separator <NUM>.

Accordingly, in the electrode assembly <NUM> manufactured in this embodiment, the adhesive <NUM> is disposed at the same position between the electrodes <NUM> and <NUM> and the separator <NUM>, so that there is an advantage in that the process time and efficiency can be increased.

<FIG> is a cross-sectional view showing an electrode assembly according to another embodiment of the present disclosure.

Referring to <FIG>, in the electrode assembly <NUM> according to the present embodiment, the adhesive <NUM> is disposed between the electrodes <NUM> and <NUM> and the separator <NUM>, and the adhesive <NUM> disposed in adjacent layers may be arranged in a staggered form. For example, as shown in <FIG>, in the electrode assembly <NUM> of this embodiment, the first adhesive <NUM>-<NUM> positioned between the lower portion of the first electrode <NUM> and the separator <NUM> and the second adhesive <NUM>-<NUM> positioned between the upper portion of the first electrode <NUM> and the separator <NUM> may be disposed to be shifted from each other. In this case, the first adhesive <NUM>-<NUM> and the second adhesive <NUM>-<NUM> may be disposed to be shifted from each other, and may be applied at the same distance. This may be similarly explained in the case of the adhesive <NUM> positioned between the second electrode <NUM> and the separator <NUM>.

However, the present invention is not limited thereto, and the structure in which the first adhesive <NUM>-<NUM> and the second adhesive <NUM>-<NUM> are displaced from each other may be manufactured by applying various methods.

Accordingly, in the electrode assembly <NUM> of this embodiment, the adhesive <NUM> is disposed between the electrodes <NUM> and <NUM> and the separator <NUM>, and the adhesive <NUM> disposed in adjacent layers is staggered. Thus, it is possible to minimize an increase in the thickness of the electrode assembly <NUM> due to the adhesive <NUM>. In addition, since the adhesives <NUM> disposed in adjacent layers are displaced from each other, the adhesive <NUM> may be more easily dissolved in the electrolyte included in the battery cell described above.

Claim 1:
A unit cell (<NUM>) comprising:
a separator and an electrode that are alternately stacked by a predetermined number;
a first adhesive part (<NUM>) that is positioned between the separator and the electrode and is composed of a first adhesive composition; characterised by
a second adhesive part (<NUM>) that is positioned between the separator and the other separator and is composed of a second adhesive composition,
wherein a shear strength of the first adhesive part (<NUM>) is equal to or smaller than a shear strength of the second adhesive part (<NUM>).