Electrode assemblies and electrochemical elements containing the same

Abstract

The present invention provides an electrode assembly and a method for manufacturing the same, in which the detachment between electrodes and the short-circuit phenomenon between electrodes are improved by providing an adhesive portion in a predetermined region of the interface between the separation membrane and the electrode. The electrode assembly of the present invention is an electrode assembly comprising an electrode, a separation membrane, and a counter electrode, wherein the electrode and the counter electrode each include a tab extending from a current collector, and at least one surface of the interface between at least one of the electrode and the counter electrode and the separation membrane includes an adhesive portion formed in at least one end region in the direction in which the tab of the electrode is located.

Description

[Technical Field]

[0001] The present invention relates to an electrode assembly including an adhesive portion and an electrochemical element including the same. [Background technology]

[0002] With the increasing technological development and demand for mobile devices, the demand for rechargeable batteries as an energy source is rapidly increasing. Recently, rechargeable batteries have been realized as power sources for electric vehicles (EVs) and hybrid electric vehicles (HEVs). As a result, a lot of research is being conducted on rechargeable batteries that can meet diverse requirements.

[0003] In particular, there is a high demand for lithium-ion batteries with high energy density, high discharge voltage, and output stability. Among these, lithium-ion batteries used as power sources for electric vehicles and hybrid electric vehicles require high-power characteristics that allow them to deliver significant output in a short time. Therefore, there is continued interest in improving battery safety for use in such lithium-ion batteries.

[0004] Figure 1 shows a top view of a conventional electrode assembly, and Figure 2 shows a cross-sectional view of a conventional electrode assembly. On the other hand, secondary batteries are typically manufactured by a lamination process in the order of positive electrode current collector / positive electrode / separator / negative electrode / negative electrode current collector, followed by a cross-section slitting process. In this case, as can be seen in Figures 4 and 5, during continuous charging and discharging, the laminated secondary battery experiences electrode breakdown due to the electrical behavior at the interface between the electrode and the separator, resulting in interfacial desorption between the electrode and the separator in the affected area (shaded region). This causes deposits such as Dead Li to form, leading to expansion of the secondary battery due to the deposits and a decrease in the battery's safety and performance. [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Therefore, the present invention solves the above-mentioned problems, The aim is to provide an electrode assembly that effectively solves the desorption phenomenon between the electrode and the separation membrane, a method for manufacturing the electrode assembly, and an electrochemical element containing the same.

[0006] In particular, we aim to provide an electrode assembly that effectively solves the short-circuit problem between the positive and negative electrodes, a method for manufacturing the electrode assembly, and an electrochemical element including the same.

[0007] In particular, the method for manufacturing the electrode assembly of the present invention aims to effectively improve the desorption phenomenon between the electrode and the separation membrane that occurs at the slitting position. [Means for solving the problem]

[0008] To solve the above problems, According to one aspect of the present invention, an electrode assembly of the following embodiment is provided.

[0009] The electrode assembly according to the first embodiment is An electrode assembly comprising an electrode, a separation membrane, and a counter electrode, The electrode and the counter electrode each include a tab extending from the current collector, and at least one surface of the interface between at least one of the electrode and the counter electrode and the separator film includes an adhesive portion formed in at least one end region in the direction in which the tab of the electrode is located.

[0010] According to the second embodiment, in the first embodiment, The adhesive portion may be formed in each of the following locations: one end region in the direction in which the tab of the electrode is located on the interface between the electrode and the separation membrane, and the other end region in the direction in which the tab of the counter electrode is located on the interface between the counter electrode and the separation membrane.

[0011] According to the third embodiment, in the first or second embodiment, The adhesive portion may be formed in a width region of 10% from one end, based on 100% of the total width of the separation film.

[0012] According to the fourth embodiment, in any one of the first to third embodiments, the total width of the separation membrane may be 5 mm to 800 mm.

[0013] According to the fifth embodiment, in any one of the first to fourth embodiments, the thickness of the bonding portion may be 0.5 to 2 μm.

[0014] According to the sixth embodiment, in any one of the first to fifth embodiments, the separation membrane includes a polymer substrate and a porous coating layer formed on at least one surface of the polymer substrate and containing inorganic particles and a binder, and the bonding portion may be formed in a partial region on the surface of the porous coating layer.

[0015] According to another aspect of the present invention, a method for manufacturing an electrode assembly of the following embodiment is provided.

[0016] The method for manufacturing an electrode assembly according to the seventh embodiment is (S1) forming bonding portions at a predetermined interval on at least one surface of a separation membrane film; (S) positioning an electrode on the surface where the bonding portion is formed; (S3) slitting the region where the bonding portion is formed; (S4) forming tabs by notching in the region where the slit electrode contacts the bonding portion.

[0017] According to the eighth embodiment, in the seventh embodiment, the step (S1) may include forming bonding portions on each of both surfaces of the separation membrane, and the step (S2) may include positioning an electrode and a counter electrode on both surfaces of the separation membrane where the bonding portion is formed.

[0018] According to yet another aspect of the present invention, an electrochemical element of the following embodiment is provided.

[0019] The electrochemical element according to the ninth embodiment is An electrode assembly according to any of the first to sixth embodiments is housed in a case. [Effects of the Invention]

[0020] An electrode assembly according to one embodiment of the present invention is provided with a separation membrane / adhesion portion / electrode structure in the slitting region during the manufacturing process of the electrode assembly, and can effectively prevent or improve the detachment phenomenon between the separation membrane and the electrode in the slitting region. This can suppress the occurrence of short circuits between electrodes.

[0021] This has a beneficial effect in reducing the risk of secondary battery swelling and deterioration of battery stability and performance caused by precipitates that form at the desorption site between the electrode and the separation membrane. [Brief explanation of the drawing]

[0022] [Figure 1] The basic structure of a conventional electrode assembly is shown. Electrode assembly 1 includes an electrode 10, a separator membrane 30, and a counter electrode (not shown), and each of the electrode and the counter electrode may include tabs 13, 23 extending from a current collector. [Figure 2] A cross-sectional view of the basic structure of a conventional electrode assembly is shown. The electrode assembly includes a positive electrode 10, a negative electrode 20, and a separator membrane 30 interposed between the positive and negative electrodes. Each of the positive and negative electrodes may include current collectors 11 and 21, active material layers 12 and 22, and tabs 13 and 23 extending from the current collectors. [Figure 3] A schematic diagram of the lamination process during the manufacture of a conventional electrode assembly is shown. The electrode assembly can be manufactured by forming electrodes 10 on a separation membrane 30 containing a porous substrate 31 and porous coating layers 32, 32', followed by a slitting process. [Figure 4]A schematic diagram of the region where electrode collapse occurs in a conventional electrode assembly is shown. As an example, in electrode assembly 1, electrode collapse and separation of the separation membrane and electrode (shaded region) may occur at one end of the interface between the separation membrane 30 and the electrode 10 in the direction where tabs 13 and 23 are located. [Figure 5] This diagram shows a schematic cross-section of the region where desorption occurs between the separation membrane and the electrode in a conventional electrode assembly. [Figure 6] A top view of an electrode assembly according to one embodiment of the present invention is shown. The electrode assembly 1 according to one embodiment of the present invention may include an adhesive portion 40 formed in one end region in the direction in which the electrode tabs 13 and 23 are located at the interface between the separation membrane 30 and the electrode 10. [Figure 7] A cross-sectional view of an electrode assembly according to one embodiment of the present invention is shown. The electrode assembly according to one embodiment of the present invention may include an adhesive portion 40 formed on the interface surface between each of the electrode and the counter electrode and the separation membrane, at least one end region in the direction in which the tab of the electrode is located. [Figure 8] A schematic diagram of the manufacturing process of an electrode assembly according to one embodiment of the present invention is shown. The manufacturing process of an electrode assembly according to one embodiment of the present invention may include forming adhesive portions 40 at predetermined intervals on a separation membrane 30, forming electrodes 10, and then slitting the positions where the adhesive portions have been formed. [Modes for carrying out the invention]

[0023] The present invention will be described in detail below.

[0024] In this specification, when a part is said to "include" a component, this means, unless otherwise stated, that it may further include other components rather than excluding them.

[0025] In this specification, the term "A and / or B" means "A or B, or all of these."

[0026] The present invention relates to an electrode assembly and an electrochemical element containing the same. Examples of the electrochemical element include primary batteries, secondary batteries, supercapacitors, and electric double-layer capacitors. The secondary battery may more specifically be a lithium-ion secondary battery.

[0027] The electrode assembly and electrochemical element of the present invention will be described in more detail below with reference to the drawings.

[0028] An electrode assembly according to one aspect of the present invention includes an electrode, a separator membrane, and a counter electrode, the electrode and the counter electrode each including a tab extending from a current collector. At this time, at least one surface of the interface between at least one of the electrode and the counter electrode and the separator membrane includes an adhesive portion formed in at least one end region in the direction in which the tab of the electrode is located.

[0029] In one embodiment of the present invention, the separation membrane may include adhesive portions formed on both sides facing the electrode and the counter electrode, at least at one end in the direction in which the tabs of the opposing electrodes are located.

[0030] Specifically, in one embodiment of the present invention, the electrode assembly may include adhesive portions formed in each of the following directions: one end region in the direction in which the tab of the electrode is located on the interface between the electrode and the separation membrane, and the other end region in the direction in which the tab of the counter electrode is located on the interface between the counter electrode and the separation membrane.

[0031] Figure 6 shows a top view of an electrode assembly according to one embodiment of the present invention. Referring to Figure 6, the electrode assembly 1 is provided with electrodes 10 and a counter electrode (not shown) on both sides of a separation membrane 30, and at this time, an adhesive portion 40 is provided between the separation membrane and the electrode in one end region in the direction in which the tab portions 13 and 23 of the electrodes are located.

[0032] In one embodiment of the present invention, the adhesive portion may be formed in a width region of 10% from one end, based on 100% of the total width of the separation film. Specifically, the adhesive portion may be formed with a constant thickness in a width region of 0% to 10% or 0% to 5% from one end, based on 100% of the total width of the separation film.

[0033] In this specification, the width of the separation membrane means the length in the direction in which the adhesive portion extends from one end of the separation membrane on which the adhesive portion is formed. For example, in an electrode assembly including the separation membrane, if the position of the separation membrane at the corner where the electrode tab is formed is defined as having a width of 0%, and the position of the separation membrane at the opposite corner is defined as having a width of 100%, then it is preferable for the adhesive portion to be formed with a constant thickness in a region from 0% to 10% or 5% of the width, in terms of low resistance of the electrode assembly, but the present invention is not limited thereto.

[0034] According to one embodiment of the present invention, the electrode assembly may include a rectangular electrode and a separation membrane, in which case the width of the separation membrane may be measured with reference to the direction in which the electrode tab of the electrode assembly is located. That is, the total width of the separation membrane means the width of the separation membrane in the direction in which the electrode tab is formed, and it means that the adhesive portion can be formed in a width region of 10% from one end of the electrode assembly where the tab is formed.

[0035] In one embodiment of the present invention, the total width of the separation membrane may be, for example, 5 mm to 800 mm, but is not limited thereto.

[0036] In one embodiment of the present invention, when the adhesive portion is formed in the above-mentioned region, it is preferable in that it is effective in improving the adhesive strength between the electrode and the separation film by the adhesive portion and preventing short circuits between the electrodes, while maintaining the electrochemical performance of the electrode assembly. However, the present invention is not limited thereto.

[0037] Figure 7 shows a cross-sectional view of an electrode assembly according to one embodiment of the present invention. Referring to Figure 7, the electrode assembly can prevent or improve detachment between the electrode and the separation membrane by providing an adhesive portion between the separation membrane and the electrode at one end of the electrode in the direction of the tab portion of the electrode where detachment between the electrode and the separation membrane occurs in the conventional method.

[0038] Referring to Figure 7, since the adhesive portion 40 is formed at one end of the electrode assembly, the adhesive portion is not included in the inner area of ​​the interface between the electrodes 12 and 22 and the separation membrane 30. In this case, it is preferable that the adhesive portion be formed thinly in order to maintain a uniform overall thickness of the electrode assembly.

[0039] In one embodiment of the present invention, the adhesive portion is formed at one end region of the interface between the separation film and the electrode, and may be formed to have a thickness (height) of, for example, 0.5 to 2 μm. By forming the adhesive portion to the above-mentioned thickness, it is possible to achieve the advantage that there is no or minimal thickness deviation of the electrode assembly between the region where the adhesive portion is not formed and the region where the adhesive portion is formed, but the present invention is not limited thereto.

[0040] In this specification, the thickness of the adhesive portion can be measured by a known method for measuring the thickness of each component of the separation film, for example, by using a film thickness measuring instrument from Mitutoyo, but the measurement method is not limited thereto.

[0041] According to one embodiment of the present invention, the adhesive portion may include an adhesive binder. The adhesive binder may include, for example, an acrylic polymer, a rubber polymer, a cellulosic polymer, a PVDF polymer, polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyacrylamide (PAM), or a mixture of two or more of these. The acrylic polymer may include, for example, polyalkyl (meth)acrylate, and the "alkyl" may be a C1 to C5 alkyl, but is not particularly limited. The rubber polymer may be a rubber polymer containing at least one butadiene unit, and examples include, but are not limited to, polybutadiene rubber, styrene-butadiene rubber, nitrile butadiene rubber, etc. The cellulosic polymer is a general term for cellulose and cellulose derivatives, and examples include, but are not limited to, cellulose, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose phthalate, etc. The aforementioned PVDF-based polymers can refer collectively to polymers containing vinylidene fluoride as a monomer, such as polyvinylidene fluoride (PVDF) and polyvinylidene-co-hexafluoropropylene, but are not limited to these.

[0042] In one embodiment of the present invention, the separation membrane separates or insulates the positive electrode and the negative electrode from each other, enabling the transport of lithium ions between the positive electrode and the negative electrode, and can be used without particular limitations as long as it is the type typically used in electrochemical elements. For example, the separation membrane may be provided in the form of a film.

[0043] In one embodiment of the present invention, the separation membrane may include a polymer substrate and a porous coating layer formed on at least one surface of the polymer substrate, which contains inorganic particles and a binder. In this case, the adhesive portion may be formed on a portion of the surface of the porous coating layer.

[0044] The following describes the configuration of the porous substrate and the porous coating layer as an example.

[0045] In one embodiment of the present invention, the porous substrate refers to a substrate in which a plurality of pores are formed inside, acting as a porous ion-conduction barrier that allows ions to pass through while blocking electrical contact between the negative electrode and the positive electrode. The pores are interconnected, and a gas or liquid can pass from one side of the substrate to the other.

[0046] In one embodiment of the present invention, the porous substrate can be a porous polymer film containing a thermoplastic resin, from the viewpoint of providing a shutdown function. Here, the shutdown function refers to a function that prevents thermal runaway of the battery by blocking ion movement when the temperature of the battery rises, as the thermoplastic resin melts and closes the holes in the porous substrate.

[0047] In one embodiment of the present invention, a thermoplastic resin with a temperature of less than 200°C is preferred as the thermoplastic resin used for the porous substrate. The thermoplastic resin can be used without particular limitations as long as it is used as a substrate for a separation membrane, for example, but is not limited to polyolefins, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyethersulfone, polyphenylene oxide, polyphenylene sulfide, polyethylene naphthalene, or mixtures of two or more of these.

[0048] In one embodiment of the present invention, the porous substrate may be a polyolefin substrate.

[0049] In one embodiment of the present invention, the porous coating layer may contain inorganic particles and further contain a binder resin, wherein the inorganic particles are coated on all or at least part of their surface by the binder resin. In this case, the inorganic particles are surface-bonded and / or point-bonded via the binder resin. For example, the inorganic particles and binder resin in the porous coating layer may be present in a weight ratio of 95:5 to 50:50. The porous coating layer has a large number of micropores inside, and these micropores are interconnected, giving it the structural characteristics of a porous layer that allows gas or liquid to pass from one surface to the other.

[0050] In one embodiment of the present invention, the porous coating layer may have a porous structure resulting from pores caused by interstitial volumes (spaces between inorganic particles). The size and porosity (ratio of pore volume) of these pores can be adjusted according to the size and size distribution of the particles. Such a structure enhances the safety of the electrochemical element by increasing resistance to metallic foreign matter present on the electrodes and suppressing shrinkage of the porous polyolefin substrate.

[0051] In one embodiment of the present invention, the porous coating layer comprises a plurality of nodes, each containing inorganic particles and a binder polymer covering at least a portion of the surface of the inorganic particles, and one or more filaments formed in a thread-like manner from the binder polymer of the nodes, wherein the filaments include node connecting portions extending from the nodes and connecting other nodes, and the node connecting portions may have a structure in which a plurality of filaments derived from the binder polymer intersect each other to form a three-dimensional network structure.

[0052] In one embodiment of the present invention, the porous coating layer may be formed by an SRS (Safety Reinforced Separator) manufacturing method, a CCS (Ceramic Coated Separator) manufacturing method, or other known manufacturing methods, but is not limited thereto.

[0053] In one embodiment of the present invention, the inorganic particles can be used without particular limitation as long as they are electrochemically stable. That is, the inorganic particles that can be used in the present invention are not particularly limited as long as they do not undergo oxidation and / or reduction reactions within the operating voltage range of the electrochemical element to which they are applied (e.g., Li / Li+ reference 0~5V). Non-limiting examples of such inorganic particles include BaTiO3, Pb(Zr,Ti)O3(PZT), and Pb 1-x La x Zr 1-y Ti y O3(PLZT, 0 <x<1、0<y<1)、Pb(Mg 1 / 3 Nb 2 / 3 Examples include O3-PbTiO3 (PMN-PT), hafnia (HfO2), SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, SiO2, Y2O3, Al2O3, SiC, and TiO2, and one or more of these may be included.

[0054] In one embodiment of the present invention, when the porous coating layer contains a binder resin, the binder resin may include, for example, a polyvinylidene fluoride-based resin (PVdF-based resin). In one embodiment of the present invention, the PVdF-based resin may include one or more homopolymers of vinylidene fluoride (i.e., polyvinylidene fluoride), copolymers of vinylidene fluoride and copolymerizable monomers, and mixtures thereof. In one embodiment of the present invention, the monomer may be, for example, a fluorinated monomer and / or a chlorine-based monomer. Non-limiting examples of the fluorinated monomers include vinyl fluoride; trifluoroethylene (TrFE); chlorofluoroethylene (CTFE); 1,2-difluoroethylene; tetrafluoroethylene (TFE); hexafluoropropylene (HFP); perfluoro(alkyl vinyl) ethers such as perfluoro(methyl vinyl) ether (PMVE), perfluoro(ethyl vinyl) ether (PEVE), and perfluoro(propyl vinyl) ether (PPVE); perfluoro(1,3-dioxole); and perfluoro(2,2-dimethyl-1,3-dioxole) (PDD), and one or more of these may be included.

[0055] In one embodiment of the present invention, the first porous coating layer and the second porous coating layer may have the same composition, but may be formed with different compositions as needed, and the present invention is not limited thereto.

[0056] In one embodiment of the present invention, the binder in the porous coating layer may be the same as or different from the adhesive binder of the adhesive portion, or may be selected independently of them.

[0057] The following describes in detail other configurations of the electrode assembly according to one aspect of the present invention.

[0058] In one embodiment of the present invention, if the electrode is a positive electrode, the counter electrode may be a negative electrode, and if the electrode is a negative electrode, the counter electrode may be a positive electrode.

[0059] positive electrode As described above, the positive electrode includes a current collector, an active material layer formed on at least one surface of the current collector, and an insulating coating portion formed around the entire circumference of the outer periphery of the active material layer.

[0060] The current collector is not particularly limited as long as it supports the active material layer and has high conductivity without inducing chemical changes in the battery. For example, copper, stainless steel, aluminum, nickel, titanium, palladium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, silver, etc., and aluminum-cadmium alloys can be used.

[0061] The current collector can have fine irregularities formed on its surface to strengthen the bonding force with the positive electrode active material, and can be used in a variety of forms such as film, sheet, foil, mesh, net, porous material, foam, and nonwoven fabric.

[0062] The active material layer includes a positive electrode active material and may further include a conductive material, a binder, and additives.

[0063] In one embodiment of the present invention, the positive electrode active material may include, for example, lithium transition metal oxide; lithium metallic iron phosphorus oxide; lithium nickel-manganese-cobalt oxide; an oxide in which a portion of lithium nickel-manganese-cobalt oxide is substituted with another transition metal; or two or more of these. Specifically, the positive electrode active material may include, for example, layered compounds such as lithium cobalt oxide (LiCoO2) and lithium nickel oxide (LiNiO2), or compounds substituted with one or more transition metals; chemical formula Li 1+x Mn 2-xO4 (where x is from 0 to 0.33), lithium manganese oxides such as LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, Cu2V2O7; chemical formula LiNi 1-x M x O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x = 0.01 to 0.3), Ni-site type lithium nickel oxide represented by; chemical formula LiMn 2-x M x O2 (where M = Co, Ni, Fe, Cr, Zn or Ta, and x = 0.01 to 0.1) or lithium manganese composite oxide represented by Li2Mn3MO8 (where M = Fe, Co, Ni, Cu or Zn); lithium metal phosphate LiMPO4 (where M = Fe, CO, Ni, or Mn); lithium nickel-manganese-cobalt oxide Li 1+x (Ni a Co b Mn c ) 1-x O2 (x = 0 to 0.03, a = 0.3 to 0.95, b = 0.01 to 0.35, c = 0.01 to 0.5, a + b + c = 1); oxide in which part of lithium nickel-manganese-cobalt oxide is substituted with aluminum Li a [Ni b Co c Mn d Al e 1-f M1 f O2 (M1 is one or more selected from the group consisting of Zr, B, W, Mg, Ce, Hf, Ta, La, Ti, Sr, Ba, F, P and S, 0.8 ≤ a ≤ 1.2, 0.5 ≤ b ≤ 0.99, 0 < c < 0.5, 0 < d < 0.5, 0.01 ≤ e ≤ 0.1, 0 ≤ f ≤ 0.1); oxide in which part of lithium nickel-manganese-cobalt oxide is substituted with other transition metals Li 1+x (Ni a Co b Mn c M d ) 1-xExamples include O2 (x=0~0.03, a=0.3~0.95, b=0.01~0.35, c=0.01~0.5, d=0.001~0.03, a+b+c+d=1, M is one selected from the group consisting of Fe, V, Cr, Ti, W, Ta, Mg, and Mo), disulfide compounds; Fe2(MoO4)3, etc., but are not limited to these.

[0064] In one embodiment of the present invention, the conductive material is a substance that electrically connects the electrolyte and the positive electrode active material and serves as a path for electrons to move from the current collector to the positive electrode active material, and can be used without limitation as long as it is conductive as an electrode component that is physically distinct from the carbon contained in the sulfur-carbon composite.

[0065] In one embodiment of the present invention, the conductive material can be, for example, carbon black such as Super-P, Denka Black, Acetylene Black, Ketjen Black, Channel Black, Furnace Black, Lamp Black, Thermal Black, and Carbon Black; carbon derivatives such as carbon nanotubes and fullerenes; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; or conductive polymers such as polyaniline, polythiophene, polyacetylene, and polypyrrole, either alone or in mixtures.

[0066] In one embodiment of the present invention, the content of the conductive material may be 0 to 10% by weight, for example, 1 to 10% by weight, relative to the total weight of the active material layer. If the content of the conductive material is less than the above range, electron transfer between the positive electrode active material and the current collector may not be easy, and the voltage and capacity may decrease. Conversely, if it exceeds the above range, the relative ratio of the positive electrode active material may decrease, and the total energy (charge amount) of the battery may decrease. Therefore, it is preferable to determine an appropriate content within the above range.

[0067] In one embodiment of the present invention, the positive electrode active material layer includes a positive electrode active material and a binder polymer, but does not need to include a conductive material. Since the positive electrode does not contain a conductive material, it has the advantage of being able to contain a larger amount of positive electrode active material.

[0068] In one embodiment of the present invention, the positive electrode binder maintains the positive electrode active material on the positive electrode current collector and organically connects the positive electrode active material to further enhance the binding force between them, and all binder polymers known in the industry can be used.

[0069] In one embodiment of the present invention, the binder in the positive electrode active material layer may be the same as or different from the binder in the insulating coating portion, i.e., the first adhesive binder and / or the second adhesive binder, or may be selected independently of these.

[0070] In one embodiment of the present invention, the binder in the positive electrode active material layer may include, for example, a fluororesin-based binder containing polyvinylidene fluoride (PVdF) or polytetrafluoroethylene (PTFE); a rubber-based binder containing styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber, styrene-isoprene rubber, etc.; a cellulose-based binder containing carboxyl methyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, etc.; a polyalcohol-based binder; a polyolefin-based binder containing polyethylene, polypropylene, etc.; a polyimide-based binder; a polyester-based binder; a polyacrylic-based binder such as polyacrylic acid (PAA); a silane-based binder; a polyurethane-based binder; or a mixture of two or more of these. Furthermore, the binder polymer may include a copolymer comprising repeating units derived from two or more of these binders.

[0071] In one embodiment of the present invention, the content of the binder polymer may be 0.5 to 30 wt% with respect to 100 wt% of the total positive electrode active material layer. When the content of the binder polymer satisfies this range, the physical properties of the positive electrode are improved, the phenomenon of the active material and conductive material falling off in the positive electrode can be prevented, and the ratio of active material to conductive material in the positive electrode can be appropriately controlled to ensure battery capacity.

[0072] negative electrode The negative electrode may include a negative electrode current collector and a negative electrode active material layer coated on one or both sides of the negative electrode current collector. Alternatively, the negative electrode may be a lithium metal plate.

[0073] The negative electrode current collector is for supporting the negative electrode active material layer, as explained in the description of the positive electrode current collector.

[0074] The negative electrode active material layer may include, in addition to the negative electrode active material, a conductive material, a binder, etc. In this case, the conductive material and binder are as described above.

[0075] The negative electrode active material is lithium (Li + This may include materials that can be reversibly intercalated or deintercalated, materials that can react with lithium ions to reversibly form lithium-containing compounds, lithium metals, or lithium alloys.

[0076] The aforementioned lithium ion (Li + The material from which the lithium ion (Li) can be reversibly inserted or removed may be, for example, crystalline carbon, amorphous carbon, or a mixture thereof. +A substance capable of reversibly forming a lithium-containing compound by reacting with ) may be, for example, tin oxide, titanium nitrate, or silicon. The lithium alloy may be, for example, an alloy of lithium (Li) with a metal selected from the group consisting of sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), aluminum (Al), and tin (Sn).

[0077] According to another aspect of the present invention, a method for manufacturing the electrode assembly described above is provided.

[0078] The method for manufacturing the electrode assembly is as follows: (S1) A step of forming adhesive portions on at least one surface of the separation film at predetermined intervals, (S2) The step of positioning the electrode on the surface on which the adhesive portion is formed, (S3) A step of slitting the region where the adhesive portion is formed, (S4) The step of forming a tab by notching in the region of the slit electrode that is in contact with the adhesive portion.

[0079] Figure 8 shows a schematic diagram of a method for manufacturing an electrode assembly according to one embodiment of the present invention.

[0080] Referring to Figure 8, the procedure may include forming adhesive portions at predetermined intervals on at least one surface of the separation film, forming electrodes thereon, and then slitting the region where the adhesive portions were formed.

[0081] First, step (S1) is a step of forming adhesive portions at predetermined intervals on at least one surface of a long, strip-shaped separation film. In this specification, the separation film is referred to as a separation film to distinguish it from the "separation membrane" contained in the electrode assembly manufactured after slitting, and apart from its long length, the structure of the separation film is based on the structure of a separation membrane.

[0082] In one embodiment of the present invention, an adhesive portion is formed on at least one of the surfaces of the separation film on which electrodes will be formed later. Preferably, when electrodes and counter electrodes are formed on both sides of the separation film, it is preferable that adhesive portions are formed on both sides of the separation film.

[0083] In one embodiment of the present invention, the method for forming the adhesive portion is not particularly limited and can be any known coating technique that can form a certain pattern, such as slot die coating, inkjet coating, microgravure coating, curtain coating, etc.

[0084] Next, step (S2) is the step of forming electrodes on the surface on which the adhesive portion is formed. This is done by known methods for forming electrodes in the manufacturing process of the electrode assembly, and such methods are omitted in this specification.

[0085] Hereafter, step (S3) is a step of slitting the region where the adhesive portion is formed. Specifically, this is done to improve the desorption phenomenon between the separation membrane and the electrode in the slitting region by adjusting the slitting region to the position of the adhesive portion formed between the separation membrane and the electrode during the manufacture of the electrode assembly.

[0086] In one embodiment of the present invention, the specific steps for the slitting are carried out by known methods, and their description is omitted herein.

[0087] Next, step (S4) is a step of forming a tab portion on the electrode assembly. The electrode assembly is such that the electrode extends in the direction in which an adhesive portion is formed between the separation membrane and the electrode, and the electrode tab is formed by notching after slitting the electrode assembly.

[0088] In one embodiment of the present invention, the notching step for forming the electrode tab is carried out by a known method, and its description is omitted herein.

[0089] The electrode assembly manufactured by the above method has the advantage of improving the detachment phenomenon between the electrode and the separator membrane and thereby improving the safety of short circuits between the electrodes, by providing an adhesive portion between the electrode and the separator membrane in at least one end region in the direction in which the electrode tab is located. However, the mechanism of the present invention is not limited to this.

[0090] According to yet another aspect of the present invention, an electrochemical element can be provided in which the above-described electrode assembly is housed in a case.

[0091] In one embodiment of the present invention, the case can be one that is commonly used as a battery case, and is not particularly limited in terms of its external shape depending on the battery's application. For example, the case may be cylindrical, rectangular, pouch-type, or coin-type, using a can.

[0092] Once the electrode assembly described above is completed, it can be stored in a case and sealed using a conventional method to manufacture an electrochemical element. In this case, the electrochemical element may be, for example, a lithium secondary battery. [Explanation of symbols]

[0093] 1: Electrode assembly 10: Positive electrode 11: Positive electrode current collector 12: Positive electrode active material layer 13: Positive Tab 20: Negative electrode 21: Negative electrode current collector 22: Negative electrode active material layer 23: Negative electrode tab 30: Separation membrane 31: Porous base material 32, 32': Porous coating layer 40: Adhesive part

Claims

1. An electrode assembly comprising an electrode, a separation membrane, and a counter electrode, The electrode and the counter electrode each include a tab extending from the current collector, An electrode assembly characterized in that at least one surface of the interface between the electrode and the counter electrode and the separation membrane includes an adhesive portion formed in at least one end region in the direction in which the tab of the electrode is located.

2. One end region in the direction in which the tab of the electrode is located on the interface between the electrode and the separation membrane, The electrode assembly according to claim 1, characterized in that it includes an adhesive portion formed on each of the interface between the counter electrode and the separation membrane, in the direction in which the tab of the counter electrode is located, and an end region of the interface between the counter electrode and the separation membrane, in which the tab of the counter electrode is located.

3. The electrode assembly according to claim 1, characterized in that the adhesive portion is formed in a width region of 10% from one end, based on 100% of the total width of the separation membrane.

4. The electrode assembly according to claim 1, characterized in that the total width of the separation membrane is 5 mm to 800 mm.

5. The electrode assembly according to claim 1, characterized in that the thickness of the adhesive portion is 0.5 to 2 μm.

6. The separation membrane comprises a polymer substrate and a porous coating layer formed on at least one surface of the polymer substrate, which contains inorganic particles and a binder. The electrode assembly according to claim 1, characterized in that the adhesive portion is formed in a part of the surface area of ​​the porous coating layer.

7. (S1) A step of forming adhesive portions on at least one surface of the separation film at predetermined intervals, (S2) The step of positioning the electrode on the surface on which the adhesive portion is formed, (S3) A step of slitting the area in which the adhesive portion is formed, A method for manufacturing an electrode assembly, comprising the step of (S4) forming a tab by notching in the region of the slit electrode that is in contact with the adhesive portion.

8. Step (S1) includes the step of forming adhesive portions on each of the two surfaces of the separation membrane, The method for manufacturing an electrode assembly according to claim 7, characterized in that the (S2) step includes the step of positioning an electrode and a counter electrode on both sides of the separation membrane on which the adhesive portion is formed.

9. An electrochemical element characterized in that the electrode assembly according to any one of claims 1 to 6 is housed in a case.

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