Electrode assembly having insulation coating portion, preparation method thereof, and secondary battery including the electrode assembly

Abstract

The present invention relates to an electrode assembly including an insulating coating portion, a method for manufacturing the same, and a secondary battery including the electrode assembly, and has the advantage of being able to improve the insulating characteristics and physical properties of the electrode assembly by forming an insulating coating portion in a spare area of ​​the separator.

Description

Technology Field

[0001] The present invention relates to an electrode assembly including an insulating coating portion, a method for manufacturing the same, and a secondary battery including the electrode assembly. Background Technology

[0003] As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly rising, and accordingly, research is being conducted on secondary batteries capable of meeting various requirements.

[0004] In terms of battery shape, there is high demand for prismatic and pouch-type rechargeable batteries, which are thin and suitable for applications in products such as mobile phones; in terms of materials, there is high demand for lithium-ion batteries and lithium-ion polymer batteries, which possess advantages such as high energy density, discharge voltage, and output safety.

[0005] These secondary batteries can be classified into cylindrical, prismatic, and pouch-type cells depending on their shape. Among them, pouch-type cells are attracting significant attention because they can be stacked with high integration density, have high energy density per unit weight, are inexpensive, and are easy to deform.

[0006] Meanwhile, the electrode assembly embedded in the pouch-type battery case is a rechargeable power generator composed of a stacked structure of a positive electrode, a separator, and a negative electrode, and is classified into a jelly-roll type, which is wound with a separator interposed between long sheet-type positive and negative electrodes coated with active material, and a stack type, which is sequentially stacked with a plurality of positive and negative electrodes of a predetermined size interposed in the separator.

[0007] FIG. 1 is a schematic diagram showing a stacked battery cell, and FIG. 2 is a schematic diagram showing the changes in the stacked battery cell when the battery cell is damaged. Referring to FIG. 1 and FIG. 2, the stacked battery cell has a structure in which a plurality of positive and negative electrodes are sequentially stacked with a separator interposed therebetween. However, when the battery cell is subjected to external impact, electrode plates such as positive or negative electrodes may deform, and such deformation of electrode plates is a primary cause of ignition or explosion of the battery cell. Accordingly, rigidity against external impact is recognized as a major factor in determining the quality of the battery cell.

[0008] Figure 3 is a schematic diagram showing the collision test process of a battery cell, and Figure 4 is a diagram illustrating a photograph of the exterior of the battery cell taken after the collision test. Referring to Figure 3, the collision test on the battery cell is performed by dropping an object of a predetermined weight from a specific height while the battery cell is fixed, thereby applying an impact to the battery cell. Specifically, the collision test on the battery cell is a test of the wide sides and narrow sides of the battery cell, in which an object weighing 9.1 kg is dropped from a height of approximately 61 cm to apply an impact to the battery cell, and the safety is verified based on whether ignition occurs.

[0009] Referring to Fig. 4, when a test was performed in which an impact was applied to the front (wide sides) of a conventional pouch-type battery cell, it can be seen that the side portion of the battery cell has greater deformation than the inside. This means that the side portion of the battery cell is less stable than the inside.

[0010] In particular, the separator on the side of the battery cell may be torn due to external impact, and in such cases, there is a risk of a short circuit occurring as the positive and negative electrodes come into contact. In addition, if a large current flows within a short period of time due to overcharging, external short circuit, nail penetration, or local crush, there is a risk of ignition or explosion as the battery heats up due to heat generation.

[0011] Meanwhile, various methods have been attempted in the past to reduce the possibility of short circuits in electrodes under external shock or high temperatures, such as attaching insulating tape of a predetermined size to electrode tabs or forming an insulating coating layer.

[0012] However, since there is no technology to prevent deformation of the side regions of battery cells, there is a need to develop technology for electrode assemblies that can prevent deformation of the side regions of battery cells and improve safety. Prior art literature

[0014] Republic of Korea Registered Patent No. 10-1768195 The problem to be solved

[0015] The present invention aims to solve the above-mentioned problems by providing an electrode assembly including an insulating coating portion, a method for manufacturing the same, and a secondary battery including the electrode assembly. means of solving the problem

[0017] The present invention relates to an electrode assembly comprising an insulating coating portion. In one example, the present invention relates to an electrode assembly comprising an anode, a cathode, and a separator located between the anode and the cathode, wherein the electrode assembly comprises n separators having a size larger than that of the anode and the cathode (where n is an integer greater than or equal to 2), and has a structure in which one of the anode and the cathode is interposed between the k-th separator and the k+1-th separator (where k is an integer greater than or equal to 1 and less than or equal to n-1), and may have a structure in which an insulating coating portion is formed in a spare region between the k-th separator and the k+1-th separator to be in contact with at least one end of the electrode.

[0018] In another example, the insulating coating portion may be a structure coated such that a portion of the separator and one surface of the electrode overlap.

[0019] In addition, the width (W1) of each insulating coating part may be a structure formed in an area of ​​15% or less based on the width (W2) of the separator.

[0020] In another example, when the insulating coating portion is coated so as to overlap the separator and the electrode, the ratio (W1:W3) of the width length (W1) of each insulating coating portion and the width length (W3) of the overlapping area of ​​the electrode may be in the range of 5:5 to 8:2.

[0021] In addition, in the electrode assembly according to the present invention, the k-th separator and the k+1-th separator may be structured to be bonded to each other by an insulating coating portion.

[0022] In one example, the insulating coating may be a mixture of a binder polymer and inorganic particles.

[0023] In a specific example, the binder polymer may be one or more selected from the group consisting of polyvinylidene fluoride, styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylonitrile-butadiene-styrene rubber, acrylic rubber, butyl rubber, fluororubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene copolymer, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, ethylene-propylene-diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, hydroxypropylmethylcellulose, hydroxypropylcellulose, and diacetylcellulose.

[0024] In addition, the above inorganic particles may be one or more selected from the group consisting of alumina (Al2O3), boehmite (AlOOH), silica (SiO2), titanium dioxide (TiO2), aluminum hydroxide (Al(OH)3), magnesium oxide (MgO), magnesium hydroxide (Mg(OH)2), zinc oxide (ZnO), barium titanate (BaTiO), aluminum nitride (AIN), boron nitride (BN), silicon carbide (SiC), beryllium oxide (BeO), potassium nitrate (KNO3), and ammonium diphosphate (NH4H2PO4).

[0025] Furthermore, the separator is a polymer membrane or a multi-membrane formed from any one polymer selected from the group consisting of polyethylene, polypropylene, polyethyleneterephthalate, polybutyleneterephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenyleneoxide, cyclic olefin copolymer, polyphenylenesulfide, and polyethylenenaphthalene, or a mixture of two or more of these. It can be woven or non-woven fabric.

[0026] Meanwhile, the insulating coating portion may be formed along two sides adjacent to the side where the electrode tab of the electrode is formed.

[0028] The present invention provides a method for manufacturing an electrode assembly as described above. A method for manufacturing an electrode assembly comprising a cathode, an anode, and a separator located between the cathode and the anode comprises the step of preparing a laminate by stacking one electrode, either a cathode or an anode, between n separators (where n is an integer greater than or equal to 2) having a larger size than the cathode and the anode, and between the k-th separator and the k+1-th separator (where k is an integer greater than or equal to 1 and less than or equal to n-1). Meanwhile, in the step of preparing the laminate, the process of applying an insulating coating liquid to a spare area of ​​the separator after stacking an electrode on one surface of the separator may include the step of applying the insulating coating liquid so as to be in contact with at least one end of the electrode.

[0029] In addition, the method for manufacturing an electrode assembly according to the present invention may further include the step of drying a laminate coated with an insulating coating solution at a temperature range of 50°C to 200°C; and the step of pressurizing the laminate at the temperature range.

[0030] The process of applying the above insulating coating solution to a spare area of ​​the separator may include applying the insulating coating solution such that a portion of the separator and one side of the electrode overlap.

[0031] In addition, the process of applying the insulating coating solution to the spare area of ​​the separator can be performed by applying the insulating coating solution in one or more ways selected from the group consisting of spray coating, slot die coating, and roll coating.

[0033] The present invention provides a secondary battery comprising the electrode assembly described above. In a specific example, the secondary battery according to the present invention may have a structure in which the electrode assembly is embedded in a pouch.

[0034] In a specific example, the electrode assembly may include one or more selected from the group consisting of a mono-cell and a bi-cell. Effects of the invention

[0036] According to the electrode assembly including an insulating coating portion of the present invention, the method for manufacturing the same, and the secondary battery including the electrode assembly, there is an advantage in that the insulating characteristics and physical properties of the electrode assembly can be improved by forming an insulating coating portion in a spare area of ​​the separator.

[0037] In addition, the above-mentioned insulating coating prevents damage to the inside of the electrode assembly, thereby suppressing the occurrence of a short circuit and effectively preventing the risk of explosion and fire caused by the short circuit. Brief explanation of the drawing

[0039] Figure 1 is a schematic diagram showing a typical stacked battery cell. Figure 2 is a schematic diagram showing the changing pattern of a stacked battery cell when the battery cell is damaged. Figure 3 is a diagram schematically showing the collision test process of a battery cell. Figure 4 is a diagram illustrating a photograph of the exterior of a battery cell taken after a collision test of the battery cell. FIG. 5 is a schematic diagram of an electrode assembly according to the present invention. FIG. 6 is a front view of an electrode assembly according to the present invention. FIG. 7 is a schematic diagram showing a separator with an insulating coating formed thereon in one embodiment of the present invention. FIG. 8 is a front view of an electrode assembly according to the present invention. FIG. 9 is a schematic diagram showing a separator with an insulating coating formed thereon in another embodiment of the present invention. FIG. 10 is a flowchart illustrating a method for manufacturing an electrode assembly according to the present invention. FIGS. 11 and 12 are schematic drawings illustrating a method for manufacturing an electrode assembly according to the present invention. Specific details for implementing the invention

[0040] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are to be described in detail in the detailed description.

[0041] However, this is not intended to limit the invention to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0042] In the present invention, terms such as "comprising" or "having" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0043] Furthermore, in the present invention, when a part such as a layer, film, region, or plate is described as being "on" another part, this includes not only cases where it is "immediately above" the other part, but also cases where there is another part in between. Conversely, when a part such as a layer, film, region, or plate is described as being "under" another part, this includes not only cases where it is "immediately below" the other part, but also cases where there is another part in between. Additionally, in the present application, being "placed on" may include cases where it is placed on the lower part as well as on the upper part.

[0044] In the present invention, "electrode assembly" refers to only one or more unit cells, or refers to an assembled form in which two or more unit cells are formed with a separator interposed between them. Additionally, in the present invention, "unit cell" is understood to be a unit comprising an anode, a cathode, and a separator interposed between the anode and the cathode, and may include, for example, one or more types of unit cells.

[0045] In addition, the electrode assembly in the present invention provides a stacked electrode assembly. The term "stacked electrode assembly" may refer to an electrode assembly in which a plurality of positive and negative electrodes, cut into units of a predetermined size, are sequentially stacked with a separator interposed therebetween.

[0047] Hereinafter, an electrode assembly including an insulating coating portion according to the present invention, a method for manufacturing the same, and a secondary battery including the electrode assembly will be described in detail with reference to the drawings.

[0049] [First embodiment]

[0050] The present invention provides an electrode assembly including an insulating coating portion as a first embodiment.

[0052] electrode assembly

[0053] FIG. 5 is a schematic diagram of an electrode assembly according to the present invention, and FIG. 6 is a cross-sectional view of an electrode assembly according to the present invention (A-A'). Referring to FIG. 5 and FIG. 6, the electrode assembly (100) according to the present invention is configured to include an anode (1111), a cathode (1112), and a separator (120) located between the anode (1111) and the cathode (1112).

[0054] The electrode assembly (100) may include n separators (120) having a larger size than the positive electrode (1111) and the negative electrode (1112) (where n is an integer greater than or equal to 2). Additionally, it has a structure in which one of the positive electrode (1111) and the negative electrode (1112) is interposed between the k-th separator and the k+1-th separator (where k is an integer greater than or equal to 1 and less than or equal to n-1).

[0055] Meanwhile, the electrode assembly (100) according to the present invention is characterized in that an insulating coating portion (130) is formed along the length of the spare region between the k-th separator (120) and the k+1-th separator (120) so as to be in contact with at least one end of the electrode (110). In a specific example, the insulating coating portion (130) may be a structure formed along two sides adjacent to the side where the electrode tab (111) of the electrode (110) is formed. Typically, the positive electrode (1111) and the negative electrode (1112) include a current collector and a composite layer formed on one or both sides of the current collector, and an electrode tab (111) extending from the current collector is formed. In the present invention, the insulating coating portion (130) may be a structure formed along the length direction of the separator (120) and along two sides adjacent to the side where the electrode tab (111) is formed. The above insulating coating portion (130) is formed in a spare area of ​​the separator (120) to improve the safety of the electrode assembly (100). Here, "spare area" may refer to the empty space at both ends of the electrode (110) when the electrode (110) is placed between the k-th separator (120) and the k+1-th separator (120). Specifically, it refers to both sides along the longitudinal direction of the pouch-type secondary battery between the k-th separator (120) and the k+1-th separator (120), and may refer to two sides that are orthogonal to the side where the electrode tab (114) of the electrode (110) is formed in the separator (120).

[0056] Conventionally, methods were attempted to form an insulating tape or an insulating coating layer on the electrode tab (111) portion to reduce the possibility of a short circuit of the electrode (110) under external impact or high temperature of the battery cell. However, there was a problem in that a short circuit of the electrode (110) occurred due to deformation of the side area or tearing of the separator caused by external impact of the battery cell. In particular, pouch-type battery cells are manufactured with a long electrode (110) length to increase energy density, and in such cases, the side area may be structurally less stable than the electrode tab (111) area. Accordingly, the present invention provides an electrode assembly (100) having a structure in which an insulating coating portion (130) in contact with both ends of the electrode (110) is formed in the spare area between the k-th separator (120) and the k+1-th separator (120) to improve the structural stability of the battery cell or electrode assembly.

[0057] In the electrode assembly (100) according to the present invention, the k-th separator (120) and the k+1-th separator (120) may be structured to be bonded to each other by an insulating coating portion (130). In particular, the electrode assembly (100) including the insulating coating portion (130) is coated on the separator (120), thereby preventing damage to the separator (120). Furthermore, even if damage occurs to the separator (120), the insulating coating portion (130) in the spare area can prevent a hard short that occurs instantaneously by flowing a large current.

[0058] Additionally, the separator (120) is interposed between the anode (1111) and the cathode (1112), and may be an insulating thin film having high ion permeability and mechanical strength. The separator (120) is not particularly limited as long as it is commonly used in the industry, but specifically, a sheet or nonwoven fabric made of chemically resistant and hydrophobic polypropylene; glass fiber; or polyethylene may be used, and in some cases, a composite separator (120) in which inorganic particles / organic particles are coated by an organic binder polymer on a porous polymer substrate such as the sheet or nonwoven fabric may be used. When a solid electrolyte such as a polymer is used as the electrolyte, the solid electrolyte may also serve as the separator. Furthermore, the pore diameter of the separator may be an average of 0.01 to 10 μm, and the thickness may be an average of 5 to 300 μm.

[0059] In one example, the separator (120) is formed of any one polymer selected from the group consisting of polyethylene, polypropylene, polyethyleneterephthalate, polybutyleneterephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenyleneoxide, cyclic olefin copolymer, polyphenylenesulfide, and polyethylenenaphthalene, or a mixture of two or more of these. It may be a polymer membrane or a multi-layer membrane thereof, a woven fabric or a non-woven fabric. In a specific example, the separator (120) may be a polymer membrane selected from the group consisting of polyethylene, polypropylene, polyethyleneterephthalate, polybutyleneterephthalate, and polyester, and in some cases, a composite separator coated with an organic binder polymer such as polyvinylidene fluoride (PVdF) or styrene-butadiene rubber (SBR) may be used.For example, if the above separator (120) is a composite separator coated with an organic binder polymer such as polyvinylidene fluoride (PVdF) or styrene butadiene rubber (SBR), it can be more easily bonded to the insulating coating part (130) described above, thereby improving the safety of the electrode assembly (100).

[0060] The insulating coating portion (130) may have a structure in which an insulating material, which is a mixture of a binder polymer and inorganic particles, is applied. In a specific example, the insulating coating portion (130) may provide an insulating coating portion (130) with excellent tensile strength and impact strength by using an insulating material in which inorganic particles are mixed with a binder polymer.

[0061] In a specific example, the binder polymer may be one or more selected from the group consisting of polyvinylidene fluoride, styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylonitrile-butadiene-styrene rubber, acrylic rubber, butyl rubber, fluororubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene copolymer, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, ethylene-propylene-diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, hydroxypropylmethylcellulose, hydroxypropylcellulose, and diacetylcellulose. Alternatively, it may be one or more of polyvinylidene fluoride, styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylonitrile-butadiene-styrene rubber, acrylic rubber, butyl rubber, fluororubber, and polytetrafluoroethylene. For example, the binder polymer may be polyvinylidene fluoride.

[0062] In addition, the above inorganic particles may be one or more selected from the group consisting of alumina (Al2O3), boehmite (AlOOH), silica (SiO2), titanium dioxide (TiO2), aluminum hydroxide (Al(OH)3), magnesium oxide (MgO), magnesium hydroxide (Mg(OH)2), zinc oxide (ZnO), barium titanate (BaTiO), aluminum nitride (Al), boron nitride (BN), silicon carbide (SiC), beryllium oxide (BeO), potassium nitrate (KNO3), and ammonium diphosphate (NH4H2PO4); specifically, they may be one or more selected from the group consisting of alumina (Al2O3), boehmite (AlOOH), and silica (SiO2).

[0063] Furthermore, the above-mentioned inorganic particles may be one or more selected from the group consisting of potassium nitrate (KNO3) and ammonium diphosphate (NH4H2PO4). For example, when potassium nitrate (KNO3) and ammonium diphosphate (NH4H2PO4) are used as inorganic particles, there is an effect of delaying heat transfer, etc., in the event of ignition or explosion of the battery cell.

[0064] The above inorganic particles may have an average particle size in the range of 0.001㎛-100㎛, 0.01㎛-70㎛, or 1㎛-50㎛. If the particle size of the inorganic particles is less than the lower limit of the above range, the stress between the inorganic particles increases, causing the particles to clump together and making it difficult to disperse them uniformly within the polymer binder; if it exceeds the upper limit, it does not mix with the polymer binder, and sedimentation of the inorganic particles occurs, making it difficult to form a uniform insulating coating (113).

[0065] The weight ratio of the binder polymer and the inorganic particles may be in the range of 1:99 to 50:50, or in the range of 5:95 to 30:70. Meanwhile, if the content ratio of the binder polymer is too high, the pore size and porosity of the separation membrane may be reduced, and if the content of the inorganic particles is too high, the adhesion to the separation membrane (120) may be weakened because the content of the binder polymer is low.

[0066] The mixture of the polymer binder and inorganic particles may, if necessary, include one or more solvents selected from water, glycerol, ethylene glycol, propylene glycol, dimethyl sulfoxide, dimethyl formamide, acetonitrile, ethylene carbonate, furfuryl alcohol, and methanol. In this case, the content of solids per 100 parts by weight of solvent may be 1 to 50 parts by weight, or 5 to 40 parts by weight, or 10 to 40 parts by weight.

[0068] FIG. 7 is a schematic diagram showing a separator with an insulating coating formed thereon in one embodiment of the present invention. Referring to FIG. 7, the separator (120), which has a larger size than the electrode (110), has a structure in which the electrode (110) is laminated on one side and an insulating coating (130) is formed along both sides of the electrode (110). That is, as previously described, the insulating coating (130) can be formed in a spare area along the length of the separator (130).

[0069] At this time, the insulating coating portion (130) may come into contact with both ends of the electrode (110). Here, the two ends of the electrode (110) refer to the ends of the two sides adjacent to the side where the electrode tab (111) is formed. The insulating coating portion (130) is formed to come into contact with both ends of the electrode (110), thereby preventing the active material, etc. from escaping from both ends of the composite layer, and providing thermal stability even if the active material is escaping.

[0070] The width (W1) of each insulating coating part (130) may be 15% or less based on the width (W2) of the separator (120). Specifically, the width (W1) of each insulating coating part (130) may be in the range of 2% to 15%; 4% to 14%; 6% to 13%; 8% to 12%; 10% to 11%; or 10% based on the width (W2) of the separator (120). If the width (W1) of each insulating coating part (130) is less than the lower limit of the range based on the width (W2) of the separator (120), the width (W1) of the insulating coating part (113) formed on the electrode (110) is too small, making it difficult to prevent deformation of the side area of ​​the battery cell, and if the width (W1) of each insulating coating part (113) exceeds the upper limit of the range based on the width (W2) of the separator (120), it is difficult to control the shape change of the battery cell, which may cause defects in appearance. The width (W1) of the insulating coating part (113) is not particularly limited, and for example, the insulating material may be in the range of 0.5 mm to 10 mm.

[0071] Furthermore, although not shown in the drawing, the electrode (110) may further include an insulating coating portion (not shown) along the side where the electrode tab (111) is formed.

[0072] The electrode assembly (100) including the insulating coating portion (130) according to the present invention can prevent damage inside the electrode assembly (100) by the above-described configuration, thereby suppressing the occurrence of a short circuit and preventing the risk of explosion and fire caused by the short circuit.

[0074] [Second embodiment]

[0075] The present invention provides an electrode assembly comprising the insulating coating portion described above as a second embodiment.

[0077] electrode assembly

[0078] FIG. 8 is a front view of an electrode assembly according to the present invention, and FIG. 9 is a schematic diagram showing a separator with an insulating coating formed thereon in another embodiment of the present invention. Referring to FIG. 8 and FIG. 9, the electrode assembly (200) according to the present invention comprises n separators (n is an integer greater than or equal to 2) having a larger size than the positive electrode (2111) and the negative electrode (2112), an electrode (110) is interposed between the k-th separator (220) and the k+1-th separator (220), and an insulating coating (230) is formed in a spare area between the k-th separator (220) and the k+1-th separator (220) to contact both ends of the electrode (110).

[0079] At this time, the insulating coating portion (230) may be formed along the length of the electrode (210) and may be structured to be in contact with at least one end along the length of the electrode (210). In a specific example, the insulating coating portion (230) may be formed along two sides adjacent to the side where the electrode tab (211) of the electrode (210) is formed, and may be coated so that a portion of the separator (220) and one side of the electrode (210) overlap. This means that the insulating coating portion (230) is formed at the boundary surface between the separator (220) and the electrode (210), and the insulating coating portion (230) may be formed to cover both ends of the electrode (210).

[0080] In this case, internal damage to the electrode assembly (200) can be prevented to suppress the occurrence of a short circuit, and active material, etc. can be prevented from detaching from both ends of the composite layer in the electrode (210).

[0081] The ratio (W1:W3) of the width (W1) of each insulating coating part (230) and the width (W3) of the overlapping area of ​​the electrode (210) may be in the range of 5:5 to 8:2. More specifically, the ratio (w1:w3) of the width (W1) of each insulating coating part (230) and the width (W3) of the overlapping area of ​​the electrode (210) may be in the range of 6:4 to 7:3, for example, 7:3. Meanwhile, if the width (W1) of the overlapping area of ​​each insulating coating part (230) is too long, the area of ​​the insulating coating part (230) increases, and since the area of ​​the composite layer decreases, the energy density of the battery cell may decrease, and the performance of the battery cell may also be degraded.

[0082] Meanwhile, although the area where the insulating coating portion (230) overlaps with the electrode (210) is not shown in the drawing, it may be coated on one side of the retaining portion of the electrode (210), one side of the uncoated portion of the electrode (210), or on one side of the retaining portion and the uncoated portion.

[0083] The electrode assembly (200) including the insulating coating portion (230) according to the present invention can prevent damage inside the electrode assembly (200) by the above-described configuration, thereby suppressing the occurrence of a short circuit and preventing the risk of explosion and fire caused by the short circuit.

[0085] [Third Embodiment]

[0086] The present invention provides, as a third embodiment, a method for manufacturing an electrode assembly including the insulating coating portion described above.

[0088] Method for manufacturing an electrode assembly

[0089] FIG. 10 is a flowchart illustrating a method for manufacturing an electrode assembly according to the present invention, and FIG. 11 to 12 are schematic drawings illustrating a method for manufacturing an electrode assembly according to the present invention. Referring to FIG. 10 to 12, the method for manufacturing an electrode assembly according to the present invention manufactures an electrode assembly (300) comprising an anode (3111), a cathode (3112), and a separator (320) located between the anode (3111) and the cathode (3112), and includes the steps of preparing a laminate coated with an insulating coating liquid, drying the insulating coating liquid of the laminate, and pressurizing the laminate.

[0091] Step of preparing a laminate (S10)

[0092] The method for manufacturing an electrode assembly according to the present invention comprises the step of preparing a laminate by stacking one electrode (310) among an anode and a cathode between n separators (320) (n is an integer greater than or equal to 2) having a larger size than an anode and a cathode, and between the k-th separator (320) and the k+1-th separator (320) (k is an integer greater than or equal to 1 and less than or equal to n-1).

[0093] At this time, in the step of preparing the laminate, the process of applying an insulating coating liquid to a spare area of ​​the separator (320) after laminating an electrode (310) on one side of the separator may be included, and the process of applying the insulating coating liquid along two sides adjacent to the side where the electrode tab (311) of the electrode (310) is formed so as to be in contact with both ends of the electrode (310).

[0094] The step of preparing the above-mentioned laminate may involve interposing an electrode (310) on a separator (320) and then applying an insulating coating liquid to a spare area of ​​the separator (320). Then, while the insulating coating liquid is still undried, the above process may be repeated to prepare a laminate with the insulating coating liquid applied. That is, the step of preparing the above-mentioned laminate may mean the step of preparing a laminate with the insulating coating liquid applied. For example, after interposing a cathode (3112) on the first separator (320), an insulating coating liquid may be applied so as to be in contact with both ends of the cathode (3112). Then, while the insulating coating liquid is still undried, a second separator (320) may be laminated on one side of the cathode (3112). After that, after interposing an anode (3111) on one side of the second separator (320), an insulating liquid may be applied so as to be in contact with both ends of the anode (3111). A laminate can be prepared by assembling one or more of these unit cells. Here, the process of stacking a bi-cell with a first separator / cathode / second separator / cathode structure as a unit cell has been described, but is not limited thereto.

[0095] Meanwhile, the process of applying an insulating coating solution to the spare area of ​​the separator (320) can be performed by applying the insulating coating solution in one or more ways selected from the group consisting of spray coating, slot die coating, and roll coating. For example, the process of applying the insulating coating solution can be performed by slot die coating or roll coating. At this time, the insulating coating solution can be coated so as to be in contact with both ends of the electrode (310). Since the types of insulating coating solutions have been described above, a detailed explanation will be omitted.

[0096] In another example, the process of applying the insulating coating solution to the spare area of ​​the separator may be such that the insulating coating solution is applied so that a portion of the separator (120) and one side of the electrode (310) overlap. In this case, internal damage to the electrode assembly (300) can be prevented to suppress the occurrence of a short circuit, and active material, etc. can be prevented from escaping from both ends of the composite layer from the electrode.

[0098] Step of drying the insulating coating solution of the laminate (S20)

[0099] The method for manufacturing an electrode assembly according to the present invention includes a step of drying the insulating coating solution of the laminate (see FIG. 12). The step of drying the insulating coating solution can be performed by completely drying the insulating coating solution to remove moisture using a drying method commonly known in the art. In a specific example, drying can be applied by varying the method, such as a hot air method, a direct heating method, or an induction heating method, at a temperature sufficient to volatilize all moisture, but is not limited thereto. For example, the step of drying the insulating coating solution of the laminate can be performed using a hot air method.

[0100] At this time, the drying temperature may be in the range of 50°C to 200°C, or 60°C to 150°C or 70°C to 100°C. Meanwhile, if the drying temperature of the insulating coating solution is less than 50°C, the temperature may be too low and it may be difficult to completely dry the insulating coating solution, and if it exceeds 200°C, the drying temperature may be too high and deformation of the electrode or separator may occur.

[0102] Step of pressing the above laminate (S30)

[0103] The method for manufacturing an electrode assembly according to the present invention includes a step of pressing a laminate. In a specific example, this is for bonding between each component of the electrode assembly (300) and can be performed using a conventional press. Meanwhile, the step of pressing the laminate can be performed at a temperature equal to the drying temperature. When pressure is applied while the temperature is applied to the laminate, the basic unit bodies within the electrode assembly (300) can be bonded to each other. In a specific example, the k-th separator (320) and the k+1-th separator (320) can be bonded to each other by an insulating coating portion (330).

[0104] Accordingly, an electrode assembly (300) including an insulating coating portion (330) that contacts both ends of the electrode (310) can be easily manufactured in the spare region between the k-th separator (320) and the k+1-th separator (320).

[0106] [Fourth embodiment]

[0107] The present invention provides a secondary battery comprising the electrode assembly described above.

[0109] secondary battery

[0110] The electrode assembly described above can be embedded in a pouch to be manufactured as a secondary battery, and multiple such secondary batteries can be electrically connected to each other to be manufactured as a secondary battery module. Meanwhile, in the present invention, the secondary battery may be a lithium secondary battery.

[0111] The electrode assembly according to the present invention may be stacked in a stacked manner, and electrode tabs extend from each electrode plate of the electrode assembly. The electrode leads are electrically connected to a plurality of electrode tabs extending from each electrode plate, for example by welding, and are exposed to the outside of the pouch. Additionally, one or more of the positive and negative electrodes may include an insulating coating portion along two sides adjacent to the side where the electrode tab is formed. The pouch is typically made of an aluminum laminate sheet and may provide a space capable of accommodating the electrode assembly. Meanwhile, the electrode leads may be drawn out to the outside of the pouch and may extend in the same direction or opposite directions.

[0112] In the present invention, the electrode may be stacked together with a conventional electrode having an electrode active material layer formed on both sides of a current collector to form a unit cell such as a bi-cell or a mono-cell. In a specific example, the electrode assembly in the secondary battery according to the present invention may include one or more types selected from the group consisting of a mono-cell and a bi-cell. More specifically, a mono-cell is a unit cell in which electrodes of opposite polarities are arranged on both sides of the unit cell. Furthermore, a bi-cell is a unit cell in which the same polarity is arranged on both sides of the cell, such as a unit structure of positive electrode / separator / negative electrode / separator / positive electrode and a unit structure of negative electrode / separator / positive electrode / separator / negative electrode. For such mono-cells and bi-cells, as long as the electrodes on both sides of the unit cell have the same structure, the number of separators for the positive and negative electrodes forming them is not particularly limited. However, when stacking two or more unit cells, a plurality of unit cells must be stacked such that the positive and negative electrodes face each other with a separator interposed between each unit cell. For example, to construct an electrochemical cell including a secondary battery using bicells, a plurality of bicells must be stacked such that a bicell with a positive / separator / negative / separator / positive structure (positive bicell) and a bicell with a negative / separator / positive / separator / negative structure (negative bicell) face each other with a separator interposed. In some cases, a greater number of stacked bicells is possible; for example, bicells with positive / separator / negative / separator / positive / separator / negative / separator / positive and negative / separator / positive / separator / negative / separator / positive / separator / negative structures are also possible.

[0114] Meanwhile, the above electrode assembly is characterized by including an electrode assembly according to the first or second embodiment of the present invention described above, and due to such characteristics, there is an advantage of being able to improve the insulation characteristics and physical properties of the electrode assembly.

[0115] In addition, the above-mentioned insulating coating prevents damage to the inside of the electrode assembly, thereby suppressing the occurrence of a short circuit and effectively preventing the risk of explosion and fire caused by the short circuit.

[0117] The present invention has been described in more detail above through drawings and embodiments. However, the configurations described in the drawings or embodiments described in this specification are merely one embodiment of the present invention and do not represent all technical concepts of the present invention; therefore, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application. Explanation of the symbols

[0119] 10, 100, 200, 300: Electrode assembly 110, 210, 310: Electrodes 111, 211, 311: Electrode tabs 11, 1111, 2111, 3111: Positive poles 11', 1112, 2112, 3112: Cathode 12, 120, 220, 320: Separator 130, 230, 330: Insulating coating section

Claims

Claim 1 An electrode assembly comprising an anode, a cathode, and a separator located between the anode and the cathode, wherein the electrode assembly comprises n separators having a size larger than that of the anode and the cathode (where n is an integer greater than or equal to 2), and has a structure in which one of the anode and the cathode is interposed between the k-th separator and the k+1-th separator (where k is an integer greater than or equal to 1 and less than or equal to n-1), and has an insulating coating portion formed in a spare region between the k-th separator and the k+1-th separator to be in contact with at least one end of the electrode. Claim 2 In claim 1, the insulating coating portion is an electrode assembly having a structure in which a portion of the separator and one surface of the electrode are coated to overlap. Claim 3 In claim 2, the width (W1) of the insulating coating portion is 15% or less of the width (W2) of the separator. Claim 4 An electrode assembly according to claim 2, wherein the ratio (W1:W3) of the width length (W1) of the insulating coating portion and the width length (W3) of the overlapping area of ​​the electrode is in the range of 5:5 to 8:

2. Claim 5 An electrode assembly having a structure in which the k-th separator and the k+1-th separator are bonded to each other by the insulating coating portion in claim 1. Claim 6 An electrode assembly according to claim 1, wherein the insulating coating portion is a mixture of a binder polymer and inorganic particles. Claim 7 In claim 6, the binder polymer is one or more selected from the group consisting of polyvinylidene fluoride, styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylonitrile-butadiene-styrene rubber, acrylic rubber, butyl rubber, fluororubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene copolymer, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, ethylene-propylene-diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, hydroxypropylmethylcellulose, hydroxypropylcellulose, and diacetylcellulose. Assembly. Claim 8 An electrode assembly wherein the inorganic particles are one or more selected from the group consisting of alumina (Al2O3), boehmite (AlOOH), silica (SiO2), titanium dioxide (TiO2), aluminum hydroxide (Al(OH)3), magnesium oxide (MgO), magnesium hydroxide (Mg(OH)2), zinc oxide (ZnO), barium titanate (BaTiO), aluminum nitride (AIN), boron nitride (BN), silicon carbide (SiC), beryllium oxide (BeO), potassium nitrate (KNO3), and ammonium diphosphate (NH4H2PO4). Claim 9 In claim 1, the separator is a polymer membrane formed of any one polymer selected from the group consisting of polyethylene, polypropylene, polyethyleneterephthalate, polybutyleneterephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenyleneoxide, cyclic olefin copolymer, polyphenylenesulfide, and polyethylenenaphthalene, or a mixture of two or more of these. An electrode assembly characterized by being a multilayer, woven, or nonwoven fabric thereof. Claim 10 In claim 1, the insulating coating portion is an electrode assembly formed along two sides adjacent to the side where the electrode tab of the electrode is formed. Claim 11 A method for manufacturing an electrode assembly comprising an anode, a cathode, and a separator located between the anode and the cathode, comprising: a step of preparing a laminate by stacking one electrode among the anode and the cathode between n separators (where n is an integer greater than or equal to 2) having a larger size than the anode and the cathode, and between the k-th separator and the k+1-th separator (where k is an integer greater than or equal to 1 and less than or equal to n-1); wherein, in the step of preparing the laminate, the method comprises a step of applying an insulating coating liquid to a spare area of ​​the separator after stacking the electrode on one surface of the separator, wherein the insulating coating liquid is applied in contact with at least one end of the electrode. Claim 12 A method for manufacturing an electrode assembly according to claim 11, further comprising the step of drying an insulating coating solution applied to the laminate at a temperature range of 50°C to 200°C; and the step of pressurizing the laminate at the temperature range. Claim 13 A method for manufacturing an electrode assembly according to claim 11, wherein the process of applying the insulating coating solution to a spare area of ​​the separator includes the process of applying the insulating coating solution such that a portion of the separator and one surface of the electrode overlap. Claim 14 A method for manufacturing an electrode assembly according to claim 11, wherein the process of applying the insulating coating solution to a spare area of ​​the separator is characterized by applying the insulating coating solution in one or more ways selected from the group consisting of spray coating, slot die coating, and roll coating. Claim 15 A secondary battery in which an electrode assembly according to claim 1 is embedded in a pouch. Claim 16 In claim 15, the electrode assembly comprises one or more types selected from the group consisting of mono-cells and bi-cells, forming a secondary battery.

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