Patent Description:
Herein, as the capacity of the battery increases, the size of the case also increases and the processing of a thin material is drawing attention. As such, the amount of use of pouch-type batteries, which have a structure where a stack-type or stack/folding-type electrode assembly is built in a pouch-type battery case of an aluminum laminate sheet, gradually increases for the reasons of low manufacturing costs, a low weight, and an easy form modification, etc. <CIT> discloses a defect detecting device of an electrode assembly. <CIT> discloses a solid-state cell and method of manufacture thereof. <CIT> discloses an apparatus and method for manufacturing an electrode assembly.

<FIG> is a schematic diagram showing a conventional electrode manufacturing process, and <FIG> is a diagram showing a structure of an electrode assembly.

Referring to <FIG> and <FIG>, in a conventional electrode manufacturing method, an electrode active material layer <NUM> is formed by applying an electrode slurry containing an electrode active material on a current collector <NUM>, which was then dried and rolled and was then notched to thereby manufacture an electrode. A positive electrode is manufactured by coating a positive electrode slurry containing a positive electrode active material on a positive electrode current collector, and a negative electrode is manufactured by coating a negative electrode slurry containing a negative electrode active material on a negative electrode current collector.

The manufactured positive electrode <NUM> and negative electrode <NUM> and the separator <NUM> are alternately stacked to be manufactured in the form of an electrode assembly <NUM>, which is then built in a battery case, to thereby manufacture a battery cell <NUM>. Further, a normal electrode assembly <NUM> has a structure that the negative electrode <NUM> covers the positive electrode <NUM> as the width and length of the negative electrode <NUM> is set to be greater than the width and length of the positive electrode <NUM>. However, when manufacturing an electrode assembly <NUM>, as the positive electrode <NUM> or the negative electrode <NUM> is positioned at an inappropriate position, a lamination defect phenomenon in which the end of the positive electrode <NUM> exceeds the end of the negative electrode <NUM>, may occur in the electrode assembly <NUM>. Namely, the overhang phenomenon (A, B) of the positive electrode may occur in the overhang region of the negative electrode <NUM>.

As described above, when a lamination defect phenomenon occurs in the electrode assembly <NUM>, the positive electrode <NUM> and the negative electrode <NUM> may directly contact, or lithium precipitate accumulated from the negative electrode <NUM> according to the charge and discharge may contact the positive electrode, thereby causing a problem such as a short circuit.

Hence, there is a need for a method capable of detecting a lamination defect in the initial stages at the time of manufacturing an electrode assembly.

In order to solve the problems of the prior art, the present invention provides a method of detecting a lamination defect of an electrode assembly in the initial stage, an electrode assembly including an insulating member, and a battery cell including the electrode assembly.

The present invention provides method for detecting a lamination defect of an electrode assembly as laid out in appended claim <NUM>.

Further, the present invention provides an electrode assembly. In one example, an electrode assembly according to the present invention has a structure including a negative electrode, a positive electrode and a separator between the negative electrode and the positive electrode, in which the negative electrode has a structure having an insulating member having a predetermined width and a predetermined height in an overhang region of one end or two ends of one surface of the negative electrode.

Further, the present invention provides a battery cell including the electrode assembly.

According to a method of detecting a lamination defect of an electrode assembly, an electrode assembly including an insulating member, and a battery cell including the electrode assembly of the present invention, it is possible to easily detect a lamination defect in an electrode assembly by forming an insulating member in an overhang region of a negative electrode and then manufacturing an electrode assembly, and measuring the thickness of the electrode assembly.

Particularly, when manufacturing a battery cell, it is possible to easily detect whether there is a lamination defect in an electrode assembly before injecting an electrolyte solution or performing a packaging procedure.

As the inventive concept allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific form disclosed, and it should be understood to include all changes, equivalents, and substitutes included in the scope of the present invention.

The present invention relates to a method of detecting a lamination defect of an electrode assembly, an electrode assembly including an insulating member, and a battery cell including the electrode assembly.

Generally, a positive electrode and a negative electrode having an electrode slurry applied thereon and a separator are alternately stacked to be manufactured in the form of an electrode assembly, which is then built in a battery case, to thereby manufacture a battery cell. Further, a normal electrode assembly has a structure that the negative electrode covers the positive electrode as the width and length of the negative electrode is set to be greater than the width and length of the positive electrode. However, when manufacturing an electrode assembly, as the positive electrode or the negative electrode is positioned at an inappropriate position, a lamination defect phenomenon in which the end of the positive electrode exceeds the end of the negative electrode, may occur in the electrode assembly. In this case, the positive electrode and the negative electrode may directly contact, or lithium precipitate accumulated from the negative electrode according to the charge and discharge may contact the positive electrode, thereby causing a problem such as a short circuit.

As such, the present invention provides a method of detecting a lamination defect of an electrode assembly in the initial stage. Particularly, according to a method of detecting a lamination defect of an electrode assembly according to the present invention, it is possible to easily detect a lamination defect in an electrode assembly by forming an insulating member in an overhang region of a negative electrode and then manufacturing an electrode assembly, and measuring the thickness of the electrode assembly.

Hereinafter, a method of detecting a lamination defect of an electrode assembly, an electrode assembly including an insulating member, and a battery cell including the electrode assembly according to the present invention will be described in detail.

<FIG> is a flowchart showing a method of detecting a lamination defect in an electrode assembly according to the present invention.

Referring to <FIG>, a method for detecting a lamination defect of an electrode assembly according to the present invention includes: forming an insulating member having a predetermined width and a predetermined height in an overhang region of one end or two ends of one surface of a negative electrode (S10); manufacturing an electrode assembly by sequentially laminating a separator and a positive electrode on one surface of the negative electrode (S20); and determining whether there is a lamination defect in the electrode assembly by measuring a thickness of the electrode assembly (S30).

In the present invention, the overhang region of a negative electrode means a region corresponding to a predetermined width in one end or two ends of a negative electrode. Specifically, when manufacturing an electrode assembly, the negative electrode covers the positive electrode as the width and length of the negative electrode is set to be greater than the width and length of the positive electrode. At this time, the overhang region of the negative electrode means the region of the negative electrode where the positive electrode is not included when the negative electrode covers the positive electrode. Further, the overhang region of the negative electrode may mean the width of the region where an electrode tab has been arranged or its opposite region.

In the present invention, it is possible to determine whether there is a lamination defect in the electrode assembly by forming an insulating member in an overhang region of the negative electrode, and then measuring the thickness of an electrode assembly which is manufactured by sequentially laminating a negative electrode, a separator and a positive electrode. The specific method of detecting a lamination defect of an electrode assembly will be described later.

In one example, the method of detecting a lamination defect of an electrode assembly according to the present invention includes forming an insulating member having a predetermined width and a predetermined height in an overhang region of one end of one surface of the negative electrode. In a specific example, the insulating member is formed on one surface of the negative electrode using an attaching or coating process, etc..

In one example, the width of the insulating member is in a range of <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM><NUM>. Further, the height of the insulating member is in a range of <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM>. However, the width and the height of the insulating member are not limited thereto. The width and the height of the insulating member may be changed according to the structure and the size of the negative electrode and the positive electrode which are laminated at the time of manufacturing an electrode assembly.

Further, when the width of the insulating member is too large, it may be formed to exceed the overhang region of the negative electrode, and thus it is preferable to have an appropriate width. Further, when the height of the insulating member is too large, the height of the insulating member may also be measured even when the electrode assembly is normal. Hence, it is preferable that the height of the insulating member does not exceed the height of the positive electrode or positive electrode active material layer.

It is preferable that the insulating member is made of an electrically stable material, and in the negative electrode, the region of the insulating member may be a region where the capacity of a normal battery cell is not manifested. The insulating member may contain polyethylene, polypropylene, polyetherimide, polyacetal, polysulfone, polyetheretherketone, polyester, polyamide, polystyrene, polyethylene terephthalate, polyphenylene, polytetrafluoroethylene, polysiloxane, polyamide, polyvinylidene fluoride, and a copolymer thereof, or a mixture thereof. For example, the insulating member may be formed by coating polyethylene to have a predetermined width and height at the overhang region of one end of a negative electrode.

At this time, a width W1 of the negative electrode except for a region, where the insulating member has been formed, may correspond to a width W2 of the positive electrode or may be greater than the width W2 of the positive electrode. This means that the insulating member is located only on an overhang region of the negative electrode. Generally, the width of the negative electrode is greater than the width of the positive electrode, and in the case that the width W1 of the negative electrode except for the region where the insulating member has been formed is smaller than the width W2 of the positive electrode, the insulating member may be formed to exceed the overhang region of the negative electrode. Further, in the case that the width W1 of the negative electrode except for the region where the insulating member has been formed is smaller than the width W2 of the positive electrode, if the positive electrode is laminated on the upper portion of the negative electrode, the positive electrode may be laminated on the upper portion of the insulating member, and a lamination defect may occur in the electrode assembly.

Further, when the positive electrode is laminated on the upper portion of the negative electrode, if one end of the positive electrode is arranged on an overhang region of the negative electrode or is arranged to exceed the overhang region of the negative electrode where an insulating member has been formed, it may be determined that there is a lamination defect in the electrode assembly.

In another example, the method of detecting a lamination defect of an electrode assembly according to the present invention includes forming first and second insulating members in an overhang region of two ends of one surface of the negative electrode.

At this time, an interval L between first and second insulating members may correspond to a width W2 of the positive electrode or may be greater than the width W2 of the positive electrode. The interval L between the first and second insulating members means the width of the negative electrode except for the region where the insulating member has been formed. As described above, the width of the negative electrode is greater than the width of the positive electrode, and in the case that the width W1 of the negative electrode except for the region where the insulating member has been formed is smaller than the width W2 of the positive electrode, the insulating member may be formed to exceed the overhang region of the negative electrode. Further, in the case that the interval L between the first and second insulating members is smaller than the width W2 of the positive electrode, when the positive electrode is laminated on the upper portion of the negative electrode, the positive electrode may be laminated on the upper portion of the insulating member, and the lamination defect may occur in the electrode assembly.

In one example, a method of detecting a lamination defect of an electrode assembly according to the present invention includes manufacturing an electrode assembly by sequentially laminating a separator and a positive electrode on one surface of a negative electrode having the insulating member formed thereon (S20). Further, it is possible to determine whether there is a lamination defect in the manufactured electrode assembly by measuring the thickness of the manufactured electrode assembly.

The method of detecting a lamination defect of an electrode assembly according to the present invention includes determining whether there is a lamination defect in the electrode assembly by measuring a thickness of the electrode assembly (S30).

In one example, the determining of whether there is a lamination defect in the electrode assembly (S30) includes determining that there is a lamination defect in the electrode assembly if the thickness of the electrode assembly exceeds a sum of each thickness of the negative electrode, the separator, and the positive electrode. As described above, the negative electrode according to the present invention has an insulating member at the overhang region of one end. When the positive electrode is laminated on the overhang region of the negative electrode active material layer, the positive electrode is laminated on the upper portion of the insulating member. As such, when thickness of the electrode assembly is measured, the thickness of the insulating member may also be measured. As such, the thickness of the electrode assembly having a lamination defect may exceed the sum of the thickness of each of the negative electrode, the separator and the positive electrode. Namely, when the thickness of the manufactured electrode assembly exceeds the sum of each thickness of the negative electrode, the separator and the positive electrode, it is determined that there is a lamination defect in the electrode assembly.

For example, in the case that the thickness of each of the negative electrode, the separator and the positive electrode is <NUM>, <NUM>, and <NUM>, if the thickness of the manufactured electrode assembly exceeds <NUM>, it is determined that that is a lamination defect in the manufactured electrode assembly.

In another example, the determining of whether there is a lamination defect in the electrode assembly (S30) includes determining that there is no lamination defect in the electrode assembly if the thickness of the electrode assembly corresponds to a sum of each thickness of the negative electrode, the separator, and the positive electrode. This means that the positive electrode is laminated on the upper portion of the negative electrode, it is laminated on a region where the insulating member has not been formed.

For example, in the case that the thickness of each of the negative electrode, the separator and the positive electrode is <NUM>, <NUM>, and <NUM>, if the thickness of the manufactured electrode assembly is <NUM>, it is determined that that is no lamination defect in the manufactured electrode assembly.

In one example, the electrode assembly may have a structure including at least one of a bi-cell unit of a positive electrode/ negative electrode/ positive electrode structure, or a mono-cell unit of a positive electrode/ negative electrode structure. In a specific example, an electrode assembly may be a mono-cell of a positive electrode/separator/negative electrode, and the mono-cell has a separator interposed between the positive electrode and the negative electrode. Further, the separator may have a structure protruding from the positive electrode and the negative electrode because the area of the separator is greater than the area of the positive electrode and the negative electrode.

As described above, according to the present invention, it is possible to easily determine whether there is a lamination defect in the electrode assembly by measuring only the thickness of the laminated electrode assembly.

Particularly, according to the present invention, it is possible to measure the thickness of the electrode assembly by only laminating a negative electrode and a positive electrode, and it is possible to easily detect whether there is a lamination defect in an electrode assembly before injecting an electrolyte solution or performing a packaging procedure.

Further, the present invention provides an electrode assembly. More specifically, the present invention relates to an electrode assembly having a structure including a negative electrode, a positive electrode and a separator between the negative electrode and the positive electrode, in which the negative electrode has a structure having an insulating member having a predetermined width and a predetermined height in an overhang region of one end or two ends of one surface of the negative electrode.

As described above, since the negative electrode includes an insulating member, it is possible to detect a lamination defect in the initial stages at the time of manufacturing an electrode assembly.

In the present invention, the positive electrode has a structure in which a positive electrode mixture layer is stacked on one or both sides of a positive electrode current collector. In one example, the positive electrode mixture layer includes a positive electrode active material, a conductive material and a binder polymer, etc. and if necessary, may further include a positive electrode additive commonly used in the art.

The positive electrode active material may be a lithium-containing oxide, and may be the same or different. A lithium-containing transition metal oxide may be used as the lithium-containing oxide.

For example, the lithium-containing transition metal oxide may be any one or a mixture of two or more selected from the group consisting of LixCoO<NUM>(<NUM><x<<NUM>), LixNiO<NUM>(<NUM><x<<NUM>), LixMnO<NUM>(<NUM><x<<NUM>), LixMn<NUM>O<NUM>(<NUM><x<<NUM>), Lix(NiaCobMne)O<NUM>(<NUM><x<<NUM>, <NUM><a<<NUM>, <NUM><b<<NUM>, <NUM><c<<NUM>, a+b+c=<NUM>), LixNi<NUM>-yCoyO<NUM>(<NUM><x<<NUM>, <NUM><y<<NUM>), LixCo<NUM>-yMnyO<NUM>(<NUM><x<<NUM>, <NUM>≤y<<NUM>), LixNi<NUM>-yMnyO<NUM>(<NUM><x<<NUM>, <NUM>≤y<<NUM>), Lix(NiaCobMnc)O<NUM>(<NUM><x<<NUM>, <NUM><a<<NUM>, <NUM><b<<NUM>, <NUM><c<<NUM>, a+b+c=<NUM>), LixMn<NUM>-zNizO<NUM>(<NUM><x<<NUM>, <NUM><z<<NUM>), LixMn<NUM>-zCozO<NUM>(<NUM><x<<NUM>, <NUM><z<<NUM>), LixCoPO<NUM>(<NUM><x<<NUM>) and LixFePO<NUM>(<NUM><x<<NUM>), and the lithium-containing transition metal oxide may be coated with a metal or metal oxide such as aluminum (Al). Further, in addition to the lithium-containing transition metal oxide, one or more of sulfide, selenide, and halide may be used.

The positive electrode according to the present invention can be applied to various types of lithium secondary batteries, but is preferably used for high-power batteries. The positive electrode active material layer of the present invention is applied to a high content nickel (High-Ni)-based NCM battery.

In a specific example, the positive electrode active material layer according to the present invention includes an active material component having a structure represented by Chemical Formula <NUM> or Chemical Formula <NUM> below.

[Chemical formula <NUM>]     Lix(NiaCobMnc)O<NUM>.

(In the above chemical formula <NUM>, <NUM><x<<NUM>, <NUM><a<<NUM>, <NUM><b<<NUM>, <NUM><c<<NUM>, and a+b+c=<NUM>).

In Chemical Formula <NUM>, the value "a" is <NUM> or more, specifically <NUM> or more. In the Formula <NUM>, as the value "a" increases, the value "b" and/or value "c" decrease within the range satisfying the above Formula <NUM>. Through this, the positive electrode for a lithium secondary battery according to the present invention is applied to a high-Ni-based NCM secondary battery.

[Chemical formula <NUM>]     Lix(NiaCobMncAld)O<NUM>.

(In the above chemical formula <NUM>, <NUM><x<<NUM>, <NUM><a<<NUM>, <NUM><b<<NUM>, <NUM><c<<NUM>, <NUM><d<<NUM>, and a+b+c+d=<NUM>).

In the Chemical Formula <NUM>, "a" is equal to or greater than <NUM>, specifically, equal to or greater than <NUM>, and more specifically, equal to or greater than <NUM>.

The NCM secondary battery may be, for example, NCM <NUM>, NCM <NUM>, NCM <NUM> or NCM <NUM> (Ni ≥ <NUM>%). In the case of NCMA, the output is high while maintaining stability as in NCM by adding aluminum while not reducing the cobalt ratio.

The current collector used for the positive electrode is a metal having high conductivity, and any metal which the positive electrode active material slurry may be easily attached to and which is not reactive in the voltage range of the electrochemical device can be used. Specifically, non-limiting examples of the current collector for the positive electrode include aluminum, nickel, or a foil manufactured by a combination thereof.

The positive electrode active material may be included in the range of <NUM> to <NUM> wt% in the positive electrode mixture layer. When the content of the positive electrode active material satisfies the above range, it is advantageous in terms of manufacturing a high-capacity battery and providing sufficient conductivity of the positive electrode or adhesion between electrode materials.

The current collector used for the positive electrode is a metal having high conductivity, and any metal which the positive electrode active material slurry may be easily attached to and which is not reactive in the voltage range of the secondary battery can be used. Specifically, non-limiting examples of the current collector for the positive electrode include aluminum, nickel, or a foil manufactured by a combination thereof.

The positive electrode mixture layer further includes a conductive material. The conductive material is usually added in an amount of <NUM> to <NUM>% by weight based on the total weight of the mixture including the positive electrode active material. Such a conductive material is not particularly limited as long as it has conductivity without causing a chemical change in the secondary battery. For example, graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, or thermal black; conductive fiber such as carbon fiber or metal fiber; metal powder such as carbon fluoride, aluminum, or nickel powder; conductive whiskey such as zinc oxide or potassium titanate; conductive metal oxide such as titanium oxide; polyphenylene derivative, and carbon nano tube (CNT) may be used as the conductive material.

As the binder component, a binder polymer commonly used in the art may be used without limitation. For example, various kinds of binders such as polyvinylidene fluoride-co-hexafluoropropylene (PVDF-co-HFP), polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, styrene-butadiene rubber (SBR), and carboxyl methyl cellulose (CMC) may be used.

The binder polymer content is proportional to the conductive material content included in the positive electrode mixture layer. This is to impart adhesion to conductive materials whose particle size is relatively small compared to the active material and is because when the content of the conductive material increases, more binder polymer is required, and when the content of the conductive material decreases, less binder polymer can be used.

Further, the negative electrode may include a negative electrode current collector, and a mixture layer of a double layer structure formed on the negative electrode current collector.

Non-limiting examples of the current collector used for the negative electrode include copper, gold, nickel, or a foil manufactured by a copper alloy or a combination thereof. In addition, the current collector may be used by stacking substrates made of the above materials.

The separator may be made of any porous substrate used in a lithium secondary battery, and for example, a polyolefin-based porous membrane or a nonwoven fabric may be used, but the present invention is not particularly limited thereto.

Examples of the polyolefin-based porous membrane include polyethylene such as high density polyethylene, linear low density polyethylene, low density polyethylene, ultrahigh molecular weight polyethylene, and a membrane in which polyolefin-based polymers, such as polypropylene, polybutylene, or polypentene, are each formed alone or in a mixture thereof.

Polyethyleneterephthalate, polybutyleneterephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyethersulfone, polyphenyleneoxide, polyphenylenesulfide, and polyethylenenaphthalene, etc. may be used individually or as a polymer by a mixture thereof, to thereby form the non-woven fabric, in addition to polyolefin-based nonwoven fabric.

The structure of the nonwoven fabric may be a spunbonded nonwoven fabric composed of long fibers or a melt blown nonwoven fabric.

The thickness of the porous substrate is not particularly limited, but may be <NUM> to <NUM>, and the pore size and porosity present in the porous substrate are also not particularly limited, but may be <NUM> to <NUM> and <NUM> to <NUM>%, respectively.

Meanwhile, in order to improve mechanical strength of the separator composed of the porous substrate and to suppress a short circuit between the positive electrode and the negative electrode, a porous coating layer including inorganic particles and a binder polymer may be further included on at least one surface of the porous substrate.

The electrolyte solution may contain an organic solvent and an electrolyte salt, and the electrolyte salt is a lithium salt. Those conventionally used in the electrolyte solution for lithium secondary batteries may be used as the lithium salt without limitation. For example, one or more selected from the group consisting of F-, Cl-, Br-, I-, NO<NUM>-, N(CN)<NUM>-, BF<NUM>-, ClO<NUM>-, PF6-, (CF<NUM>)<NUM>PF<NUM>-, (CF<NUM>)<NUM>PF<NUM>-, (CF<NUM>)<NUM>PF<NUM>-, (CF<NUM>)<NUM>PF-, (CF<NUM>)<NUM>P-, CF<NUM>SO<NUM>-, CF<NUM>CF<NUM>SO<NUM>-, (CF<NUM>SO<NUM>)<NUM>N-, (FSO<NUM>)<NUM>N-, CF<NUM>CF<NUM>(CF<NUM>)<NUM>CO-, (CF<NUM>SO<NUM>)<NUM>CH-, (SF<NUM>)<NUM>C-, CF<NUM>(CF<NUM>)<NUM>SO<NUM>-, CF<NUM>CO<NUM>-, CH<NUM>CO<NUM>-, SCN- and (CF<NUM>CF<NUM>SO<NUM>)<NUM>N- may be included as the anion of the lithium salt.

As the organic solvent included in the electrolyte solution described above, those conventionally used in electrolyte solutions for lithium secondary batteries may be used without limitation, and for example, ethers, esters, amides, linear carbonates, and cyclic carbonates may be used alone or in combination of two or more. Among them, representatively, a cyclic carbonate, a linear carbonate, or a carbonate compound that is a mixture thereof may be included.

Specific examples of the cyclic carbonate compound include any one selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), <NUM>,<NUM>-butylene carbonate, <NUM>,<NUM>-butylene carbonate, <NUM>,<NUM>-pentylene carbonate, <NUM>,<NUM>-pentylene carbonate, vinylene carbonate, vinylethylene carbonate, and a halide thereof, and a mixture thereof.

These halides include, for example, fluoroethylene carbonate (FEC), but are not limited thereto.

In addition, specific examples of the linear carbonate compound include any one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate (EMC), methylpropyl carbonate, and ethylpropyl carbonate, or a mixture of two or more of them may be typically used, but is not limited thereto.

In particular, among the carbonate-based organic solvents, ethylene carbonate and propylene carbonate, which are cyclic carbonates, are organic solvents of high viscosity and have high dielectric constants, so that lithium salts in the electrolyte can be more easily dissociated, and if the cyclic carbonate is mixed with a low viscosity, low dielectric constant linear carbonate such as dimethyl carbonate and diethyl carbonate in an appropriate ratio, an electrolyte solution having a higher electrical conductivity can be prepared.

In addition, as the ether of the organic solvent, any one selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methylethyl ether, methylpropyl ether, and ethylpropyl ether, or a mixture of two or more thereof may be used, but is not limited thereto.

And esters among the organic solvents include any one selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, γ-valerolactone,γ-caprolactone, α-valerolactone and ε-caprolactone or a mixture of two or more of them, but the present invention is not limited thereto.

The injection of the non-aqueous electrolyte may be performed at an appropriate step in the manufacturing process of the secondary battery, depending on the manufacturing process and required physical properties of the final product.

Further, the present invention provides a battery cell including an electrode assembly. If the battery cell is a secondary battery capable of charging and discharging, it is not particularly limited. The battery cell may be a pouch-type battery cell or a cylindrical battery cell.

In a specific example, the battery cell may be a pouch-type battery cell. For example, the battery cell is a pouch type unit cell, and an electrode assembly having a positive electrode/ separator/ negative electrode structure is embedded in an exterior material of the laminate sheet in a state that is connected to electrode leads formed outside the exterior material. The electrode leads may be drawn to the outside of the sheet and may be extended in the same or opposite direction to each other.

Hereinafter, the present invention will be described in more detail through drawings and examples. As the inventive concept allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific form disclosed, and it should be understood to include all changes, equivalents, and substitutes included in the scope of the present invention, according to appended claims.

<FIG> are cross-sectional views showing a laminated structure of an electrode assembly including an insulating member in one embodiment of the present invention.

Referring to <FIG>, an electrode assembly <NUM> according to the present invention is manufactured by sequentially laminating a negative electrode <NUM>, a separator <NUM> and a positive electrode <NUM>. At this time, an insulating member <NUM> is formed on the overhang region <NUM> of one end of one surface of the negative electrode <NUM>.

Further, in the present invention, the width W1 of the negative electrode except for the region where the insulating member <NUM> has been formed is greater than the width W2 of the positive electrode. Further, when the positive electrode <NUM> is laminated on the upper portion of the negative electrode <NUM>, if one end of the positive electrode <NUM> is arranged on an overhang region <NUM> of the negative electrode <NUM> or is arranged to exceed the overhang region <NUM> of the negative electrode <NUM>, it is determined that there is a lamination defect in the electrode assembly <NUM>.

In the present invention, it is determined whether there is a lamination defect in the electrode assembly <NUM> by measuring the thickness of the electrode assembly <NUM> which is manufactured by sequentially laminating the negative electrode <NUM>, the separator <NUM>, and the positive electrode <NUM>. Further, the thickness of the electrode assembly <NUM> is measured by measuring the thickness of the region where the insulating member <NUM> is positioned. Specifically, as illustrated in <FIG>, when measuring the thickness of the electrode assembly <NUM> which is manufactured by sequentially laminating the negative electrode <NUM>, the separator <NUM>, and the positive electrode <NUM>, the thickness of the electrode assembly becomes <NUM>. At this time, the thickness of each of the negative electrode <NUM>, the separator <NUM> and the positive electrode <NUM> is <NUM>, <NUM> and <NUM>. The thickness of the electrode assembly <NUM> corresponds to the sum of the thickness of each of the negative electrode <NUM>, the separator <NUM> and the positive electrode <NUM>. As such, it can be determined that there is no lamination defect in the electrode assembly <NUM>.

As illustrated in <FIG>, when measuring the thickness of the electrode assembly <NUM> which is manufactured by sequentially laminating the negative electrode <NUM>, the separator <NUM>, and the positive electrode <NUM>, the thickness of the electrode assembly becomes <NUM>. At this time, the thickness of each of the negative electrode <NUM>, the separator <NUM> and the positive electrode <NUM> is <NUM>, <NUM> and <NUM>. The thickness of the electrode assembly <NUM> exceeds the sum of the thickness of each of the negative electrode <NUM>, the separator <NUM> and the positive electrode <NUM>. As such, it can be determined that there is a lamination defect in the electrode assembly <NUM>.

Specifically, in the present invention, an insulating member <NUM> is formed in an overhang region <NUM> of one end of the negative electrode <NUM>, and the positive electrode <NUM> is stacked on the overhang region <NUM> of the negative electrode, and when the thickness of the electrode assembly <NUM> is measured, the thickness of the insulating member <NUM> is also measured. As such, the thickness of the electrode assembly <NUM> may exceed the sum of the thickness of each of the negative electrode <NUM>, the separator <NUM> and the positive electrode <NUM>.

<FIG> are cross-sectional views showing a laminated structure of an electrode assembly including an insulating member in another embodiment of the present invention.

Referring to <FIG>, an electrode assembly <NUM> according to the present invention is manufactured by sequentially laminating a negative electrode <NUM>, a separator <NUM> and a positive electrode <NUM>. At this time, first and second insulating members <NUM> and <NUM> are formed on the overhang regions <NUM> and <NUM> of two ends of one surface of the negative electrode <NUM>.

Further, in the present invention, an interval L between first and second insulating members <NUM> and <NUM> corresponds to a width W2 of the positive electrode or is greater than the width W2 of the positive electrode. Further, when the positive electrode <NUM> is laminated on the upper portion of the negative electrode <NUM>, if one end of the positive electrode <NUM> is arranged on overhang regions <NUM> and <NUM> of the negative electrode <NUM> or is arranged to exceed the overhang regions <NUM> and <NUM> of the negative electrode <NUM>, it is determined that there is a lamination defect in the electrode assembly <NUM>.

In the present invention, it is determined whether there is a lamination defect in the electrode assembly <NUM> by measuring the thickness of the electrode assembly <NUM> which is manufactured by sequentially laminating the negative electrode <NUM>, the separator <NUM>, and the positive electrode <NUM>. Further, the thickness of the electrode assembly <NUM> is measured by measuring the thickness of the region where the insulating member <NUM>, <NUM> is positioned. Specifically, as illustrated in <FIG>, when measuring the thickness of the electrode assembly <NUM> which is manufactured by sequentially laminating the negative electrode <NUM>, the separator <NUM>, and the positive electrode <NUM>, the thickness of the electrode assembly becomes <NUM>. At this time, the thickness of each of the negative electrode <NUM>, the separator <NUM> and the positive electrode <NUM> is <NUM>, <NUM> and <NUM>. The thickness of the electrode assembly <NUM> corresponds to the sum of the thickness of each of the negative electrode <NUM>, the separator <NUM> and the positive electrode <NUM>. As such, it can be determined that there is no lamination defect in the electrode assembly <NUM>.

Specifically, in the present invention, an insulating member <NUM> is formed in an overhang region <NUM> of one end of the negative electrode <NUM>, and the positive electrode <NUM> is stacked on the overhang region <NUM> of the negative electrode, and when the thickness of the electrode assembly <NUM> is measured, the thickness of the insulating member <NUM> is also measured. As such, the thickness of the electrode assembly <NUM> may exceed the sum of the thickness of each of the negative electrode <NUM>, the separator <NUM> and the positive electrode <NUM>.

Further, as shown in <FIG>, an insulating member <NUM> is formed in an overhang region <NUM> of the other end of the negative electrode <NUM>, and the positive electrode <NUM> is stacked on the overhang region <NUM> of the negative electrode, and when the thickness of the electrode assembly <NUM> is measured, the thickness of the insulating member <NUM> is also measured. As such, the thickness of the electrode assembly <NUM> may exceed the sum of the thickness of each of the negative electrode <NUM>, the separator <NUM> and the positive electrode <NUM>.

Hence, when measuring the thickness of the electrode assembly <NUM> which is manufactured by sequentially laminating the negative electrode <NUM>, the separator <NUM>, and the positive electrode <NUM>, the thickness of the electrode assembly becomes <NUM>. The thickness of the electrode assembly <NUM> exceeds the sum of the thickness of each of the negative electrode <NUM>, the separator <NUM> and the positive electrode <NUM>. As such, it can be determined that there is a lamination defect in the electrode assembly <NUM>.

Claim 1:
A method for detecting a lamination defect of an electrode assembly (<NUM>, <NUM>, <NUM>), the method comprising:
forming an insulating member (<NUM>) having a predetermined width and a predetermined height in an overhang region of one end or two ends of one surface of a negative electrode (<NUM>, <NUM>, <NUM>);
manufacturing an electrode assembly by sequentially laminating a separator (<NUM>, <NUM>, <NUM>) and a positive electrode (<NUM>, <NUM>, <NUM>) on the one surface of the negative electrode (<NUM>, <NUM>, <NUM>); and
determining whether there is a lamination defect in the electrode assembly (<NUM>, <NUM>, <NUM>) by measuring a thickness of a region where the insulating member is positioned on the electrode assembly (<NUM>, <NUM>, <NUM>).