Electrode for lithium secondary battery and method of manufacturing same

Abstract

The present invention discloses an electrode for a lithium secondary battery, which can prevent the electrode active material layer from detaching from the electrode current collector even when the electrode active material layer contains a crosslinked binder by strengthening the adhesive force between the electrode current collector and the electrode active material layer, and a method for manufacturing the same. The electrode for a lithium secondary battery according to the present invention includes an electrode current collector, an adhesion promotion layer located on at least one surface of the electrode current collector and including a first binder and a first conductive material, and an electrode active material layer located on an upper surface of the adhesion promotion layer and including an electrode active material, a second conductive material, and a second binder, and the first binder and the second binder may include a binder polymer having a crosslinked structure.

Description

[Technical Field]

[0001] The present invention relates to an electrode for a lithium secondary battery and a method for producing the same.

[0002] This application claims priority based on Korean Patent Application No. 10-2022-0028612, filed on March 7, 2022, the entire contents of which are incorporated herein by reference. [Background technology]

[0003] Recently, interest in energy storage technology has been increasing. As the range of applications expands to include mobile phones, camcorders, laptops, and even electric vehicles, there is a growing demand for higher energy density batteries used as power sources for such electronic devices. Lithium secondary batteries are the battery that best meets these demands, and research into them is currently being actively conducted.

[0004] Such a lithium secondary battery generally includes a positive electrode made of lithium metal oxide, a negative electrode made of a carbon material or the like, an electrolyte solution containing a lithium salt and an organic solvent, and a separator interposed between the positive electrode and the negative electrode to electrically insulate them from each other.

[0005] Currently, poly(vinylidene fluoride) is widely used as a binder for positive electrodes, but in order to use poly(vinylidene fluoride) as a binder, it is necessary to use N-methyl-2-pyrrolidone (NMP) as a solvent. However, N-methyl-2-pyrrolidone has a high boiling point, which lengthens the drying process, and it is also harmful to the environment, so there are problems with the construction of recovery facilities being quite expensive.

[0006] The use of a crosslinkable binder as a positive electrode binder has the advantage that other solvents can be used instead of N-methyl-2-pyrrolidone. However, such crosslinkable binders often do not have the molecular weight of poly(vinylidene fluoride), resulting in poorer adhesion between the electrode active material layer and the electrode current collector compared to poly(vinylidene fluoride) with the same binder content.

[0007] Therefore, there is a strong need for a technology that can prevent the problem of reduced adhesive strength between the electrode active material layer and the electrode current collector while using a crosslinked binder instead of poly(vinylidene fluoride) as the binder for the positive electrode. Summary of the Invention [Problem to be solved by the invention]

[0008] Therefore, the problem to be solved by the present invention is to provide an electrode for a lithium secondary battery in which the adhesive strength between the electrode active material layer and the electrode current collector is ensured even when a crosslinked binder is contained in the electrode active material layer, and a lithium secondary battery including the electrode.

[0009] Another problem to be solved by the present invention is to provide a method for manufacturing an electrode for a lithium secondary battery, in which the adhesive strength between the electrode active material layer and the electrode current collector is ensured even when the electrode active material layer contains a crosslinked binder. [Means for solving the problem]

[0010] In order to solve the above problems, according to one aspect of the present invention, there is provided an electrode for a lithium secondary battery having the following configuration.

[0011] The first aspect is an electrode current collector; an adhesion promoting layer located on at least one surface of the electrode current collector, the adhesion promoting layer including a first binder and a first conductive material; an electrode active material layer located on an upper surface of the adhesion promotion layer and including an electrode active material, a second conductive material, and a second binder; Including, the first binder and the second binder each contain a binder polymer having a crosslinked structure, The present invention relates to an electrode for a lithium secondary battery, wherein the first binder and the second binder form a chemical bond with each other.

[0012] The second aspect is the first aspect, The first binder may comprise a crosslinked product of a first functional group-containing polymer and a first crosslinking agent.

[0013] The third aspect is the second aspect, The first functional group-containing polymer may contain repeating units derived from an isoprene monomer, repeating units derived from a butadiene monomer, repeating units derived from a cyclopentadiene monomer, repeating units derived from an ethylidene norbornene monomer, repeating units derived from a vinyl norbornene monomer, or two or more of these.

[0014] A fourth aspect is the second or third aspect, The functional group may include a carboxyl group, a (meth)acrylate group, a vinyl group, a vinyl ether group, an epoxy group, or two or more of these.

[0015] A fifth aspect is any one of the second to fourth aspects, The first crosslinker may comprise a monofunctional (meth)acrylate, a difunctional (meth)acrylate, a multifunctional (meth)acrylate, or two or more of these.

[0016] A sixth aspect is any one of the second to fifth aspects, The first crosslinker may comprise a linear or branched alkyl (meth)acrylate, a cyclic (meth)acrylate, an aromatic (meth)acrylate, or two or more of these.

[0017] A seventh aspect is any one of the second to sixth aspects, The first crosslinker may include 2-ethylhexyl acrylate, isostearyl acrylate, dicyclopentanyl acrylate, n-vinyl caprolactam, phenoxyethyl (meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-hexanediol di(meth)acrylate, tricyclodecane dimethanol diacrylate, isobornyl acrylate, polyethylene glycol diacrylate, 1,12-dodecanediol dimethacrylate, or two or more thereof.

[0018] An eighth aspect is any one of the second to seventh aspects, The weight ratio of the first functional group-containing polymer to the first crosslinking agent may be 10:90 to 90:10.

[0019] A ninth aspect is any one of the first to eighth aspects, The first binder may include an acrylic-modified polyurethane resin, an acrylic-modified polyethylene glycol resin, or a crosslinked product of both.

[0020] A tenth aspect is any one of the first to ninth aspects, The second binder may comprise a crosslinked product of a second functional group-containing polymer and a second crosslinking agent.

[0021] An eleventh aspect is the method according to the tenth aspect, The second functional group-containing polymer may contain repeating units derived from an isoprene monomer, repeating units derived from a butadiene monomer, repeating units derived from a cyclopentadiene monomer, repeating units derived from an ethylidene norbornene monomer, repeating units derived from a vinyl norbornene monomer, or two or more of these.

[0022] A twelfth aspect is the method according to the tenth or eleventh aspect, The functional group may include a carboxyl group, a (meth)acrylate group, a vinyl group, a vinyl ether group, an epoxy group, or two or more of these.

[0023] A thirteenth aspect is any one of the tenth to twelfth aspects, The second crosslinker may comprise a monofunctional (meth)acrylate, a difunctional (meth)acrylate, a multifunctional (meth)acrylate, or two or more of these.

[0024] A fourteenth aspect is any one of the tenth to thirteenth aspects, The second crosslinker may comprise a linear or branched alkyl (meth)acrylate, a cyclic (meth)acrylate, an aromatic (meth)acrylate, or two or more of these.

[0025] A fifteenth aspect is any one of the tenth to fourteenth aspects, The second crosslinker may include 2-ethylhexyl acrylate, isostearyl acrylate, dicyclopentanyl acrylate, n-vinyl caprolactam, phenoxyethyl (meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-hexanediol di(meth)acrylate, tricyclodecane dimethanol diacrylate, isobornyl acrylate, polyethylene glycol diacrylate, 1,12-dodecanediol dimethacrylate, or two or more thereof.

[0026] A sixteenth aspect is any one of the tenth to fifteenth aspects, The weight ratio of the second functional group-containing polymer to the second crosslinking agent may be 10:90 to 90:10.

[0027] A seventeenth aspect is any one of the first to sixteenth aspects, The content of the second binder may be 1.5 to 3.5 wt % based on 100 wt % of the electrode active material layer.

[0028] An eighteenth aspect is any one of the first to seventeenth aspects, The content of the first binder may be 2 to 70% by weight based on 100% by weight of the adhesion promoting layer.

[0029] A nineteenth aspect is any one of the first to eighteenth aspects, The content of the first conductive material may be 0.1 to 10% by weight based on 100% by weight of the adhesion promoting layer.

[0030] A twentieth aspect of the present invention is any one of the first to nineteenth aspects, The electrode for a lithium secondary battery may be a positive electrode.

[0031] In order to solve the above problems, according to one aspect of the present invention, there is provided a method for producing an electrode for a lithium secondary battery having the following features.

[0032] A twenty-first aspect is (S1) coating an electrode current collector with a composition for forming an adhesion promotion layer, the composition including a first functional group-containing polymer, a first crosslinking agent, a first photoinitiator, and a first conductive material, and drying the composition to form an adhesion promotion layer; (S2) irradiating the adhesion promoting layer with ultraviolet light; (S3) forming an electrode active material layer by coating an electrode active material layer-forming slurry containing an electrode active material, a second conductive material, a second functional group-containing polymer, a second crosslinking agent, and a second photoinitiator on the upper surface of the resultant product of step (S2) and drying the coating; and (S4) irradiating the result of step (S3) with ultraviolet light; The present invention relates to a method for producing an electrode for a lithium secondary battery, comprising the steps of:

[0033] A twenty-second aspect of the present invention is the twenty-first aspect of the present invention, As a result of step (S2), the crosslinked product of the first functional group-containing polymer and the first crosslinking agent may have a crosslinking degree of 10 to 80%.

[0034] A 23rd aspect of the present invention is the 21st or 22nd aspect of the present invention, The crosslinking degree of the crosslinked binder contained in the adhesion promoting layer in the result of step (S4) may be 10 to 100%.

[0035] A 24th aspect is any one of the 21st to 23rd aspects, The step (S3) forming a first electrode active material layer by coating the electrode active material layer forming slurry on the resultant surface of step (S2), drying the coating, and then irradiating the coating with ultraviolet light; and coating the electrode active material layer forming slurry on the first electrode active material layer and drying the slurry to form a second electrode active material layer.

[0036] A twenty-fifth aspect is any one of the twenty-first to twenty-fourth aspects, The first photoinitiator may comprise a Type 1 photoinitiator.

[0037] A 26th aspect of the present invention is the 25th aspect of the present invention, The first photoinitiator may further comprise a Type 2 photoinitiator.

[0038] A 27th aspect is any one of the 21st to 26th aspects, The first photoinitiator can include bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (Irgacure 819), oxide (diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide) (TPO), maleimide, 2,4,5-trimethylbenzoyl-diphenylphosphine oxide, bis(2,6-dimethyloxybenzoyl)2,4,4-trimethylpentyl)phosphine oxide, propanone, oligo(2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone, hydroxy-2-methyl-1-phenylpropan-1-one, oxide, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure 2959), or two or more thereof.

[0039] A 28th aspect is any one of the 21st to 27th aspects, The content of the first photoinitiator may be 0.05 to 15 wt % based on 100 wt % of the total weight of the first functional group-containing polymer and the first crosslinking agent.

[0040] A 29th aspect is any one of the 21st to 28th aspects, The second photoinitiator may comprise a Type 1 photoinitiator.

[0041] A 30th aspect of the present invention is the 29th aspect of the present invention, The second photoinitiator may further comprise a Type 2 photoinitiator.

[0042] A thirty-first aspect is any one of the twenty-first to thirtieth aspects, The second photoinitiator can comprise bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (Irgacure 819), oxide (diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide) (TPO), maleimide, 2,4,5-trimethylbenzoyl-diphenylphosphine oxide, bis(2,6-dimethyloxybenzoyl)2,4,4-trimethylpentyl)phosphine oxide, propanone, oligo(2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone, hydroxy-2-methyl-1-phenylpropan-1-one, oxide, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure 2959), or two or more thereof.

[0043] A thirty-second aspect is any one of the twenty-first to thirty-first aspects, The content of the second photoinitiator may be 0.05 to 20% by weight based on 100% by weight of the total weight of the second functional group-containing polymer and the second crosslinking agent.

[0044] A thirty-third aspect is any one of the twenty-first to thirty-second aspects, In the step (S2), the amount of ultraviolet light irradiation is 10 to 2,000 mJ / cm 2 It could be.

[0045] A thirty-fourth aspect is any one of the twenty-first to thirty-third aspects, In the step (S4), the amount of ultraviolet light irradiation is 200 to 10,000 mJ / cm 2 It could be.

[0046] In order to solve the above problems, according to one aspect of the present invention, there is provided a lithium secondary battery having the following configuration.

[0047] The thirty-fifth aspect is The present invention relates to a lithium secondary battery, characterized by including the electrode for a lithium secondary battery according to any one of the first to twentieth aspects. [Effects of the Invention]

[0048] In the electrode for a lithium secondary battery according to one embodiment of the present invention, a crosslinking binder is contained in the electrode active material layer, so that a solvent other than N-methyl-2-pyrrolidone can be used.

[0049] In addition, the electrode for a lithium secondary battery according to an embodiment of the present invention includes a crosslinked binder in the electrode active material layer, which has a lower electrolyte swelling property than conventional binders, thereby improving cycle characteristics or battery safety.

[0050] The electrode for a lithium secondary battery according to one embodiment of the present invention includes an adhesion promoting layer containing a cross-linking binder and a conductive material between the electrode current collector and the electrode active material layer, thereby improving the adhesive strength between the electrode active material layer and the electrode current collector even when the electrode active material layer contains a cross-linking binder, and at the same time, effectively maintaining the conductivity (electrical conductivity) of the electrode.

[0051] The drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further understand the technical concepts of the present invention as well as the content of the invention, and therefore the present invention should not be interpreted as being limited to only the matters depicted in the drawings. [Brief explanation of the drawings]

[0052] [Figure 1] 1 is a schematic diagram of an electrode for a lithium secondary battery according to one embodiment of the present invention. [Figure 2] FIG. 1 shows the results of confirming, using an infrared spectrometer (Agilent Cary 630 FT-IR), that a chemical bond exists between the first binder in the adhesion-promoting layer and the second binder in the electrode active material layer in the electrode produced in Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0053] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and words used in the specification and claims should not be construed as being limited to their ordinary or dictionary meanings, but should be construed as having meanings and concepts corresponding to the technical ideas of the present invention, in accordance with the principle that the inventors themselves can appropriately define the concepts of terms in order to best explain the invention.

[0054] Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent the entire technical idea of ​​the present invention, and that there may be various equivalents and modifications that can be substituted therefor at the time of this application.

[0055] Certain terminology is used in the following detailed description of the invention for convenience only and not for purposes of limitation. Throughout this specification, the terms "side" or "top" refer to a location and orientation in the drawings to which reference is made and should not be considered limiting. These terms include the words listed above, derivatives thereof, and words of similar import.

[0056] Throughout this specification, when a layer is said to be located on "one side" or "on top" of another layer, this means not only that the layer is in contact with the surface of one side of the other layer, but also that there is another layer between the two layers.

[0057] In this specification, terms such as "first" and "second" are used to distinguish one component from another, and each component is not limited by the terms.

[0058] An electrode for a lithium secondary battery according to one aspect of the present invention comprises: an electrode current collector; an adhesion promoting layer located on at least one surface of the electrode current collector, the adhesion promoting layer including a first binder and a first conductive material; an electrode active material layer located on an upper surface of the adhesion promotion layer and including an electrode active material, a second conductive material, and a second binder; Including, the first binder and the second binder each contain a binder polymer having a crosslinked structure; The first binder and the second binder are characterized by forming a chemical bond with each other.

[0059] FIG. 1 is a diagram showing an electrode for a lithium secondary battery according to one embodiment of the present invention.

[0060] Referring to FIG. 1, an electrode 1 for a lithium secondary battery includes an electrode current collector 10.

[0061] In one embodiment of the present invention, the electrode current collector 10 may be a positive electrode current collector or a negative electrode current collector.

[0062] The positive electrode current collector is not particularly limited as long as it is conductive and does not cause chemical changes in the battery. For example, stainless steel; aluminum; nickel; titanium; baked carbon; or aluminum or stainless steel whose surface has been treated with carbon, nickel, titanium, silver, or the like may be used.

[0063] The negative electrode current collector is not particularly limited as long as it is conductive and does not cause chemical changes in the battery. For example, copper; stainless steel; aluminum; nickel; titanium; calcined carbon; copper or stainless steel surface-treated with carbon, nickel, titanium, silver, or the like; or an aluminum-cadmium alloy may be used.

[0064] In one embodiment of the present invention, the electrode current collector 10 may have fine irregularities on its surface to enhance the adhesive strength of the positive electrode active material or the negative electrode active material.

[0065] In one embodiment of the present invention, the electrode current collector 10 may have a thickness of 3 to 500 μm.

[0066] 1, the electrode 1 for a lithium secondary battery includes an adhesion promoting layer 20 on at least one surface of the electrode current collector 10. The adhesion promoting layer 20 includes a first binder and a first conductive material.

[0067] The adhesion-promoting layer 20 is intended to improve the adhesive strength between the electrode current collector 10 and the electrode active material layer described later, and the first binder contained in the adhesion-promoting layer 20 must improve the adhesive strength between the electrode current collector 10 and the electrode active material layer while also satisfying the stability of the battery.

[0068] The first binder can ensure adhesive strength between the electrode current collector 10 and an electrode active material layer, which will be described later. In particular, since the first binder contains a binder polymer with a cross-linked structure, it has high affinity with a second binder, which will be described later, and can form a stable structure, thereby improving adhesive strength between the electrode current collector 10 and the electrode active material layer. As a result, even if the electrode active material layer, which will be described later, contains a binder polymer with a cross-linked structure that has a relatively weak adhesive strength, it is possible to prevent the electrode active material layer from detaching from the electrode current collector, thereby ensuring battery stability.

[0069] In one embodiment of the present invention, the first binder may include a crosslinked product of a first functional group-containing polymer and a first crosslinking agent. As a result of the reaction between the functional groups of the first functional group-containing polymer and the first crosslinking agent, the first binder may have a crosslinked structure.

[0070] In one embodiment of the present invention, the first functional group-containing polymer may contain repeating units derived from an isoprene monomer, repeating units derived from a butadiene monomer, repeating units derived from a cyclopentadiene monomer, repeating units derived from an ethylidene norbornene monomer, repeating units derived from a vinyl norbornene monomer, or two or more of these.

[0071] In one embodiment of the present invention, the functional group contained in the first functional group-containing polymer may include a carboxyl group, a (meth)acrylate group, a vinyl group, a vinyl ether group, an epoxy group, or two or more of these. When the first functional group-containing polymer includes the functional group, the adhesive strength of the adhesion promotion layer 20 to the electrode current collector 10 can be more easily improved, and the crosslinkability of the first functional group-containing polymer can be more easily improved.

[0072] In one embodiment of the present invention, the first functionalized polymer may include UC-102, UC-105, UC-203, LBR352, LBR361, and L-SBR-841 grades available from Kurary, Co., Ltd.; CN301, CN303, and CN307 available from Sartomer Co., Inc.; or two or more thereof.

[0073] In one embodiment of the present invention, the weight-average molecular weight of the first functional group-containing polymer may be 1,000 to 60,000 g / mol, 2,000 to 50,000 g / mol, or 3,000 to 40,000 g / mol. When the weight-average molecular weight of the first functional group-containing polymer satisfies the above range, the weight-average molecular weight of the first binder after crosslinking can be easily set to a level that easily ensures the adhesive strength between the electrode current collector 10 and the electrode active material layer.

[0074] The weight average molecular weight of the first functional group-containing polymer can be measured using gel permeation chromatography (GPC) under the following conditions. -Column: Tosoh "HLC-8321 GPC / HT" -Solvent: Trichlorobenzene (TCB) + 0.04% butylated hydroxytoluene (BHT) (after drying with 0.1% CaCl2) -Flow rate: 1.0ml / min -Sample concentration: 1.5mg / ml -Injection volume: 300μL -Column temperature: 160℃ -Detector: Refractive index (RI) detector -Standard: Polystyrene (corrected by a cubic function).

[0075] In one embodiment of the present invention, the first crosslinker may comprise a monofunctional (meth)acrylate, a difunctional (meth)acrylate, a multifunctional (meth)acrylate, or two or more thereof.

[0076] The term "monofunctional acrylate" means one that contains only one acrylate group.

[0077] By "difunctional acrylate" is meant one that contains two acrylate groups.

[0078] By "multifunctional acrylate" is meant one containing three or more acrylate groups.

[0079] Examples of the bifunctional or polyfunctional acrylate include 1,6-hexanediol dimethacrylate, 1,9-hexanediol dimethacrylate, and tricyclodecane dimethanol diacrylate.

[0080] In one embodiment of the present invention, the first crosslinker may include a linear or branched alkyl (meth)acrylate, a cyclic (meth)acrylate, an aromatic (meth)acrylate, or two or more of these.

[0081] For example, the linear acrylate may be an alkyl acrylate. The branched acrylate may be a branched alkyl acrylate such as 2-ethylhexyl acrylate or isostearyl acrylate. The cyclic acrylate may be dicyclopentanyl acrylate or n-vinyl caprolactam. The aromatic acrylate may be phenoxyethyl acrylate.

[0082] In one embodiment of the present invention, the first crosslinker may include isobornyl acrylate, polyethylene glycol diacrylate, 1,12-dodecanediol dimethacrylate, or two or more thereof.

[0083] In one embodiment of the present invention, the weight ratio of the first functional group-containing polymer to the first crosslinking agent may be 10:90 to 90:10, or 20:80 to 80:20, or 30:70 to 70:30. When the weight ratio of the first functional group-containing polymer to the first crosslinking agent satisfies this range, the first binder is more likely to have appropriate physical properties and crosslink density, which may be more advantageous in ensuring rolling performance.

[0084] In one embodiment of the present invention, the degree of crosslinking of the first binder may be 10 to 100%, or 50 to 100%, or 10 to 95%. When the degree of crosslinking of the first binder satisfies the above range, the stability of the adhesion promotion layer 20 is ensured, and excellent adhesion to the electrode active material layer can be more easily ensured.

[0085] The degree of crosslinking of the first binder can be measured by infrared spectroscopy (IR) as a ratio of the peak area of ​​the C=C double bond before crosslinking to the peak area of ​​the C=C double bond after crosslinking.

[0086] In one embodiment of the present invention, the content of the first binder may be 2 to 70 wt %, 10 to 70 wt %, or 20 to 60 wt %, based on 100 wt % of the adhesion promotion layer 20. When the content of the first binder satisfies the above range, sufficient adhesive strength between the electrode current collector 10 and the electrode active material layer described below can be easily ensured.

[0087] In one embodiment of the present invention, when the first binder is a crosslinked product of a first functional group-containing polymer and a first crosslinking agent, it may be the same material as or a different material from the second binder described below.

[0088] In one embodiment of the present invention, the first binder may include an acrylic-modified polyurethane resin, an acrylic-modified polyethylene glycol resin, or a crosslinked product of both.

[0089] In one embodiment of the present invention, the acrylic-modified polyurethane resin may include at least one compound represented by the following formula 1 or 2: [ka] In the above Chemical Formulas 1 and 2, n can be an integer of 1 to 30, or 3 to 25, or 5 to 20, or 8, and m can be an integer of 1 to 1,000, or 3 to 500, or 5 to 100, or 7 to 50, or 10 to 30, or 20.

[0090] The acrylic-modified polyethylene glycol resin may include at least one compound of the following chemical formulas 3 to 8: [ka] In the above chemical formulas 3 to 8, q can be an integer of 10 to 1000, or an integer of 50 to 500, or an integer of 100 to 350, or an integer of 150 to 250, or 200.

[0091] In one embodiment of the present invention, the acrylic-modified polyethylene glycol resin may be a (meth)acrylate compound having a hydroxy group or a cyano group, or a reaction product of (meth)acryloyl chloride with a polyethylene glycol compound; or a (meth)acrylate compound having a hydroxy group or a cyano group, or a reaction product of (meth)acryloyl chloride with a polyethylene glycol compound, and a diisocyanate compound.

[0092] Specifically, examples of the (meth)acrylate compound having a hydroxy group include 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate, examples of the (meth)acrylate compound having a cyano group include 2-isocyanatoethyl acrylate and 2-isocyanetoethyl methacrylate, and examples of the (meth)acryloyl chloride include acryloyl chloride and methacryloyl chloride.

[0093] Examples of the diisocyanate compounds include isophorone diisocyanate, hexamethylene diisocyanate, methylenephenyl diisocyanate, toluene diisocyanate, and dicyclohexylmethane diisocyanate.

[0094] The polyethylene glycol-based compound may be -(CH-CH 22 -O) n Examples include, but are not limited to, compounds having a repeating unit of - and having at least one OH group at the terminal, where n can be an integer of 1 to 1,000, or an integer of 50 to 500.

[0095] Examples of the polyethylene glycol-based compound include: [ka] Here, q can be an integer of 10 to 1000, or 50 to 500, or 100 to 350, or 150 to 250, or 200.

[0096] The first conductive material is not particularly limited as long as it has conductivity without causing any chemical change in the battery and is a component that, when mixed with the first binder, electrically connects the electrode active material layer and the electrode current collector 10 to maintain conductivity.

[0097] In one embodiment of the present invention, the first conductive material may include graphite including natural graphite, artificial graphite, etc.; carbon black including acetylene black, ketjen black, channel black, furnace black, lamp black, summer black, etc.; conductive fiber including carbon fiber or metal fiber, etc.; carbon nanotubes including single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, etc.; carbon fluoride; metal powder including aluminum powder, nickel powder, etc.; conductive whiskey including zinc oxide, potassium titanate, etc.; conductive metal oxide including titanium oxide, etc.; conductive material including polyphenylene derivatives, etc.; or two or more of these.

[0098] In one embodiment of the present invention, the first conductive material may be the same material as or different from a second conductive material described below.

[0099] In one embodiment of the present invention, the first conductive material may form a certain concentration gradient from the lower surface of the adhesion promotion layer 20 in contact with the electrode current collector 10 to the upper surface of the adhesion promotion layer 20 in contact with the electrode active material layer described below. When the first conductive material forms a certain concentration gradient as described above, a conductive path can be formed in the adhesion promotion layer 20, which may make it easier to effectively maintain the electrical conductivity of the electrode.

[0100] In one embodiment of the present invention, the content of the first conductive material may be 0.1 to 10 wt %, or 0.3 to 8 wt %, based on 100 wt % of the adhesion promotion layer 20. When the content of the first conductive material satisfies the above range, the adhesive strength between the electrode active material layer and the electrode current collector 10 can be more easily ensured without reducing the electrical conductivity of the electrode.

[0101] In one embodiment of the present invention, the thickness of the adhesion promotion layer 20 may be 0.1 to 50 μm, or 0.1 to 10 μm, or 0.1 to 5 μm. When the thickness of the adhesion promotion layer 20 satisfies this range, sufficient adhesive strength between the electrode current collector 10 and the electrode active material layer can be easily ensured, and problems such as deterioration of the electrical performance of the electrode and an increase in volume can be prevented.

[0102] 1, the electrode 1 for a lithium secondary battery includes an electrode active material layer 30 on the upper surface of the adhesion promotion layer 20. The electrode active material layer 30 includes an electrode active material, a second conductive material, and a second binder.

[0103] In one embodiment of the present invention, the electrode active material may be a positive electrode active material or a negative electrode active material.

[0104] The positive electrode active material may be a common active material used in lithium secondary batteries, such as a layered compound such as lithium cobalt composite oxide (LiCoO2) or lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; 1+x Mn 2-x Lithium manganese oxides such as LiMnO4, LiMnO3, LiMn2O3, and LiMnO2, represented by the formula LiMnO4 (where x = 0 to 0.33); lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O5, LiV3O4, V2O5, and Cu2V2O7; and the chemical formula LiNi 1-x M x Ni-site type lithium nickel oxide represented by the chemical formula LiMnO2 (where M=Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and x=0.01 to 0.3) 2-x M xExamples of the lithium manganese composite oxides include, but are not limited to, lithium manganese composite oxides represented by Li2Mn3MO5 (where M=Co, Ni, Fe, Cr, Zn, or Ta, and x=0.01 to 0.1) or Li2Mn3MO5 (where M=Fe, Co, Ni, Cu, or Zn); LiMn2O4, in which some of the Li is substituted with alkaline earth metal ions; disulfide compounds; Fe2(MoO4)3, lithium-containing cobalt oxide (LiCoO2), lithium iron phosphate compound (LiFePO4), lithium nickel cobalt aluminum oxide (Li[Ni.Co.Al]O2), lithium manganese oxide (LiMn2O4), lithium nickel manganese cobalt oxide (Li[Ni.Mn.Co]O2), and lithium nickel cobalt manganese aluminum oxide (Li[Ni.Co.Mn.Al]O2).

[0105] The negative electrode active material may be a common active material used in lithium secondary batteries, such as lithium metal or a lithium alloy, or a lithium adsorbent material such as carbon, petroleum coke, activated carbon, graphite, or other carbons.

[0106] In one embodiment of the present invention, the content of the electrode active material may be 80 to 99 wt %, 90 to 99 wt %, or 90 to 98.5 wt %, based on 100 wt % of the electrode active material layer 30. When the content of the electrode active material satisfies this range, the initial capacity of the electrode can be sufficiently ensured, and the adhesive strength between the electrode active material layer 30 and the electrode current collector 10 can be more easily ensured.

[0107] In one embodiment of the present invention, the second conductive material is not particularly limited as long as it has conductivity without causing any chemical change in the battery and is a component that maintains conductivity by electrically connecting between electrode active materials, or between the electrode active material layer 30 and the electrode current collector 10, etc.

[0108] In one embodiment of the present invention, the second conductive material may include graphite including natural graphite or artificial graphite, etc.; carbon black including acetylene black, ketjen black, channel black, furnace black, lamp black, summer black, etc.; conductive fiber including carbon fiber or metal fiber, etc.; carbon nanotubes including single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, etc.; carbon fluoride; metal powder including aluminum powder or nickel powder; conductive whiskey including zinc oxide or potassium titanate; conductive metal oxide including titanium oxide; conductive material including polyphenylene derivative; or two or more of these.

[0109] In one embodiment of the present invention, the content of the second conductive material may be 0.1 to 5 wt %, 0.3 to 4 wt %, or 0.4 to 3 wt %, based on 100 wt % of the electrode active material layer 30. When the content of the second conductive material satisfies the above range, the adhesive strength between the electrode active material layer 30 and the electrode current collector 10 can be more easily ensured without reducing the electrical conductivity of the electrode.

[0110] The second binder is a component that assists in bonding between the electrode active material and the second magnetic material, etc., and between the electrode active material and the electrode current collector, and has a crosslinked structure.

[0111] When exposed to high temperatures, electrode active materials can undergo side reactions with the electrolyte, generating gas and other problems. When a second binder having a cross-linked structure is included in the electrode active material layer, the second binder has lower electrolyte swelling characteristics than conventional electrode binders, and therefore the second binder can protect the electrode active material layer. This reduces side reactions between the electrolyte and the electrode active material, improving cycle characteristics and battery safety.

[0112] In one embodiment of the present invention, the second binder may comprise a crosslinked product of a second functional group-containing polymer and a second crosslinking agent. As a result of the reaction between the functional groups of the second functional group-containing polymer and the second crosslinking agent, the second binder may have a crosslinked structure.

[0113] In one embodiment of the present invention, the second functional group-containing polymer may contain repeating units derived from an isoprene monomer, repeating units derived from a butadiene monomer, repeating units derived from a cyclopentadiene monomer, repeating units derived from an ethylidene norbornene monomer, repeating units derived from a vinyl norbornene monomer, or two or more of these.

[0114] In one embodiment of the present invention, the functional group contained in the second functional group-containing polymer may include a carboxyl group, a (meth)acrylate group, a vinyl group, a vinyl ether group, an epoxy group, or two or more of these. When the second functional group-containing polymer includes such a functional group, the adhesive strength of the electrode active material layer 30 to the electrode current collector 10 can be more easily improved, and the crosslinkability of the second functional group-containing polymer can be more easily improved.

[0115] In one embodiment of the present invention, the second functionalized polymer may include UC-102, UC-105, UC-203, LBR352, LBR361, and L-SBR-841 grades available from Kurary, Co., Ltd.; CN301, CN303, and CN307 available from Sartomer Co., Inc.; or two or more thereof.

[0116] In one embodiment of the present invention, the weight-average molecular weight of the second functional group-containing polymer may be 1,000 to 60,000 g / mol, 2,000 to 50,000 g / mol, or 3,000 to 40,000 g / mol. When the weight-average molecular weight of the second functional group-containing polymer satisfies the above range, the weight-average molecular weight of the second binder after crosslinking can be easily set to a level that easily ensures the adhesive strength between the electrode current collector 10 and the electrode active material layer 30.

[0117] The weight average molecular weight of the second functional group-containing polymer can be measured using gel permeation chromatography (GPC) under the following conditions: -Column: Tosoh Corporation (TOSOH) "HLC-8321 GPC / HT" -Solvent: Trichlorobenzene (TCB) + 0.04% butylated hydroxytoluene (BHT) (after drying with 0.1% CaCl2) -Flow rate: 1.0ml / min -Sample concentration: 1.5mg / ml -Injection volume: 300μL -Column temperature: 160℃ -Detector: Refractive index (RI) detector -Standard: Polystyrene (corrected by a cubic function).

[0118] In one embodiment of the present invention, the second crosslinker may comprise a monofunctional (meth)acrylate, a difunctional (meth)acrylate, a multifunctional (meth)acrylate, or two or more thereof.

[0119] The term "monofunctional acrylate" means one that contains only one acrylate group.

[0120] By "difunctional acrylate" is meant one that contains two acrylate groups.

[0121] By "multifunctional acrylate" is meant one containing three or more acrylate groups.

[0122] Examples of the bifunctional or polyfunctional acrylate include 1,6-hexanediol dimethacrylate, 1,9-hexanediol dimethacrylate, and tricyclodecane dimethanol diacrylate.

[0123] In one embodiment of the present invention, the second crosslinker may include a linear or branched alkyl (meth)acrylate, a cyclic (meth)acrylate, an aromatic (meth)acrylate, or two or more of these.

[0124] For example, the linear acrylate may be an alkyl acrylate. The branched acrylate may be a branched alkyl acrylate such as 2-ethylhexyl acrylate or isostearyl acrylate. The cyclic acrylate may be dicyclopentanyl acrylate or n-vinyl caprolactam. The aromatic acrylate may be phenoxyethyl acrylate.

[0125] In one embodiment of the present invention, the second crosslinker may include isobornyl acrylate, polyethylene glycol diacrylate, 1,12-dodecanediol dimethacrylate, or two or more thereof.

[0126] In one embodiment of the present invention, the weight ratio of the second functional group-containing polymer to the second crosslinking agent may be 10:90 to 90:10, or 20:80 to 80:20, or 30:70 to 70:30. When the weight ratio of the second functional group-containing polymer to the second crosslinking agent satisfies the above range, the second binder is likely to have appropriate physical properties and crosslink density, which may be more advantageous in ensuring rolling performance.

[0127] In one embodiment of the present invention, the degree of crosslinking of the second binder may be 20 to 100%, or 50 to 100%, or 60 to 100%. When the degree of crosslinking of the second binder satisfies the above range, the content of double bonds remaining in the second binder is reduced, which may be more advantageous in ensuring the stability of the battery.

[0128] The degree of crosslinking of the second binder can be measured by infrared spectroscopy (IR) as a ratio of the peak area of ​​the C=C double bond before crosslinking to the peak area of ​​the C=C double bond after crosslinking.

[0129] In one embodiment of the present invention, the content of the second binder may be 1.5 to 3.5 wt %, or 1.5 to 2.0 wt %, based on 100 wt % of the electrode active material layer 30. When the content of the second binder satisfies this range, the initial capacity of the electrode can be sufficiently ensured, and the adhesive strength between the electrode active material layer 30 and the electrode current collector 10 can be more easily ensured.

[0130] In one embodiment of the present invention, the electrode active material layer 30 may have a thickness of 10 to 200 μm.

[0131] In the present invention, the first binder and the second binder form a chemical bond. For example, the first binder and the second binder may be cross-linked to each other. By forming a chemical bond between the first binder and the second binder, the adhesive strength between the electrode active material layer 30 and the electrode current collector 10 can be more easily improved.

[0132] The existence of such a chemical bond between the first binder and the second binder can be confirmed by removing the electrode active material layer from the electrode to expose the adhesion promoting layer, and then infrared spectroscopy (IR) can be performed. The peak of the carbon-carbon double bond (C=C) of the first binder in the adhesion promoting layer (peak position: 1633 cm -1) is reduced. This is because the double bonds in the first binder contained in the adhesion-promoting layer form chemical bonds, specifically crosslinks, with the second binder in the electrode active material layer, resulting in a significant reduction in the IR peak of the carbon-carbon double bond (C=C) in the first binder.

[0133] In an electrode for a lithium secondary battery according to one embodiment of the present invention, by incorporating a first binder containing a binder with a cross-linked structure in the adhesion promotion layer, sufficient adhesive strength can be ensured between the electrode active material layer and the electrode current collector even when a second binder containing a binder with a cross-linked structure is incorporated in the electrode active material layer.

[0134] In one embodiment of the present invention, the adhesive strength between the electrode active material layer and the electrode current collector may be 10 gf or more.

[0135] The adhesive strength between the electrode active material layer and the electrode current collector can be measured from the 90° peel strength when peeling the electrode current collector from the electrode active material layer. For example, after attaching and fixing the electrode to a slide glass, the adhesive strength can be measured from the strength when peeling the electrode current collector from the electrode active material layer at a rate of 150 mm / min at 25°C. The adhesive strength of the electrode active material layer to the electrode current collector can be measured using a peel strength measuring device (UTA-500N).

[0136] The electrode for a lithium secondary battery according to one embodiment of the present invention can be manufactured by the following method, but is not limited thereto.

[0137] A method for manufacturing an electrode for a lithium secondary battery according to one embodiment of the present invention includes: (S1) coating an electrode current collector with a composition for forming an adhesion promotion layer, the composition including a first functional group-containing polymer, a first crosslinking agent, a first photoinitiator, and a first conductive material, and drying the composition to form an adhesion promotion layer; (S2) irradiating the adhesion promoting layer with ultraviolet light; (S3) forming an electrode active material layer by coating an electrode active material layer-forming slurry containing an electrode active material, a second conductive material, a second functional group-containing polymer, a second crosslinking agent, and a second photoinitiator on the upper surface of the resultant product of step (S2) and drying the coating; and (S4) irradiating the result of step (S3) with ultraviolet light; The present invention is characterized by comprising:

[0138] Hereinafter, the main part of a method for manufacturing an electrode for a lithium secondary battery according to an embodiment of the present invention will be mainly described.

[0139] First, an adhesion-promoting layer-forming composition containing a first functional group-containing polymer, a first crosslinking agent, a first photoinitiator, and a first conductive material is coated onto an electrode current collector and dried to form an adhesion-promoting layer (S1).

[0140] For the first functional group-containing polymer, the first crosslinking agent, and the first conductive material, refer to the above contents.

[0141] The first photoinitiator crosslinks the first functional group-containing polymer and the first crosslinker.

[0142] In one embodiment of the present invention, the first photoinitiator may comprise a Type 1 photoinitiator. For example, the first photoinitiator can include bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (Irgacure 819), oxide (diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide) (TPO), maleimide, 2,4,5-trimethylbenzoyl-diphenylphosphine oxide, bis(2,6-dimethyloxybenzoyl)2,4,4-trimethylpentyl)phosphine oxide, propanone, oligo(2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone, hydroxy-2-methyl-1-phenylpropan-1-one, oxide, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure 2959), or two or more thereof.

[0143] In one embodiment of the present invention, the first photoinitiator may further include a Type 2 photoinitiator in addition to the Type 1 photoinitiator. When the Type 2 photoinitiator is further included, crosslinking efficiency can be further improved. Examples of the Type 2 photoinitiator include benzophenone, benzophenone derivatives, camphorquinone, Michler's ketone, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-methylpropyl)ketone, benzil dimethyl ketal, 2-benzyl-2-N,N-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-mercaptobenzoxazole, camphorquinone, 2-hydroxy-2-ketyl-1-(4-t-butyl)phenylpropan-1-one, 2-methyl-1-[4-(methylthiophenyl)-2-morpholinopropanone], thioxanthone, thioxanthone derivatives, or two or more thereof.

[0144] Examples of the benzophenone derivatives include hydroxyacetophenone, 4-methylbenzophenone, 4-phenylbenzophenone, 4,4'-dimethylaminobenzophenone, 4,4'-bis(diethylamino)benzophenone, 4-methoxybenzophenone, 4,4'-dimethoxybenzophenone, 4,4'-dimethylbenzophenone, 4,4'-dichlorobenzophenone, 2,4,6-trimethylbenzophenone, 4-(4-methylthiophenyl)benzophenone, 3,3'-dimethyl-4-methoxybenzophenone, methyl-2-benzoylbenzoate, 4-(2-hydroxyethyl)benzophenone ...

[0039] The compounds may include, but are not limited to, 4-(13-acryloyl-1,4,7,10,13-pentaoxatridecyl)-benzophenone, 4-benzoyl-N,N-dimethyl-N-[2-(1-oxo-2-propenyl)oxy]ethyl-benzenemethanaminium chloride, 2-hydroxy-3-(4-benzoylphenoxy)-N,N,N-trimethyl-propanaminium chloride monohydrate, 4-hydroxybenzophenone, 4-(13-acryloyl-1,4,7,10,13-pentaoxatridecyl)-benzophenone, 4-benzoyl-N,N-dimethyl-N-[2-(1-oxo-2-propenyl)oxy]ethyl-benzenemethanaminium chloride, and the like.

[0145] Examples of the thioxanthone derivatives include 2-isopropylthioxanthone, 2-chlorothioxanthone, 2-dodecylthioxanthone, 2,4-diethylthioxanthone, 2,4-dimethylthioxanthone, 1-methoxycarbonylthioxanthone, 2-ethoxycarbonylthioxanthone, 3-(2-methoxyethoxycarbonyl)-thioxanthone, 4-butoxycarbonyl-thioxanthone, and 3-butoxycarbonyl-7-methylthioxanthone. Xanthone, 1-cyano-3-chlorothioxanthone, 1-ethoxycarbonyl-3-chlorothioxanthone, 1-ethoxycarbonyl-3-ethoxythioxanthone, 1-ethoxycarbonyl-3-aminothioxanthone, 1-ethoxycarbonyl-3-phenylsulfurylthioxanthone, 3,4-di[2-(2-methoxyethoxy)ethoxycarbonyl]thioxanthone, 1-ethoxycarbonyl-3-(1-methyl-1-morpholino- Ethyl)-thioxanthone, 2-methyl-6-dimethoxymethyl-thioxanthone, 2-methyl-6-(1,1-dimethoxy-benzyl)-thioxanthone, 2-morpholinomethylthioxanthone, 2-methyl-6-morpholinomethyl-thioxanthone, N-allylthioxanthone-3,4-dicarboximide, N-octylthioxanthone-3,4-dicarboximide, N-(1,1,3,3-tetramethylbutyl)-thioxanthone- These may include, but are not limited to, 3,4-dicarboximide, 1-phenoxythioxanthone, 6-ethoxycarbonyl-2-methoxythioxanthone, 6-ethoxycarbonyl-2-methylthioxanthone, thioxanthone-2-polyethylene glycol ester, 2-hydroxy-3-(3,4-dimethyl-9-oxo-9H-thioxanthone-2-yloxy)-N,N,N-trimethyl-1-propanaminium chloride, and the like.

[0146] The content of the first photoinitiator may be 0.05 to 15 wt%, or 0.1 to 10 wt%, or 0.1 to 8 wt%, based on 100 wt% of the total weight of the first functional group-containing polymer and the first crosslinking agent. When the content of the first photoinitiator satisfies this range, the crosslinking reaction is sufficiently carried out, making it easier to ensure a desired degree of crosslinking.

[0147] In one embodiment of the present invention, the composition for forming the adhesion promoting layer can be prepared by adding a first conductive material to a dispersion medium to perform preliminary dispersion, and then adding and mixing a first functional group-containing polymer and a first crosslinking agent.

[0148] The dispersion medium is not particularly limited as long as it can dissolve the first photoinitiator and the first crosslinking agent and disperse the first conductive material. The dispersion medium may contain, for example, alcohols such as ethanol, isopropyl alcohol (IPA), and n-propyl alcohol; ketones such as acetone and methyl ethyl ketone (MEK); propyl acetate; N-methyl-2-pyrrolidone; dimethylformamide; dimethylacetamide; water; or two or more of these.

[0149] In one embodiment of the present invention, the composition for forming the adhesion promoting layer may further include a dispersant, such as polyvinylpyrrolidone, hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), ethylhydroxyethyl cellulose (EHEC), methyl cellulose (MC), sodium carboxymethyl cellulose (CMC), hydroxyalkyl methyl cellulose, cyanoethylene polyvinyl alcohol, or two or more thereof.

[0150] The adhesion-promoting layer-forming composition may be coated on the electrode current collector using a common method commonly used in the art, such as a spray coating method.

[0151] In one embodiment of the present invention, the drying can be performed by a conventional drying method used in electrode manufacturing. For example, the drying can be performed at 30°C to 100°C, or 40°C to 80°C. The drying can be performed in air for 3 to 45 seconds, or 5 to 40 seconds.

[0152] Next, the adhesion-promoting layer is irradiated with ultraviolet light (S2). By irradiating the adhesion-promoting layer with ultraviolet light, the first functional group-containing polymer and the first crosslinking agent can be crosslinked.

[0153] In one embodiment of the present invention, the irradiation dose of ultraviolet light in step (S2) is 10 to 2000 mJ / cm 2 , or 30 to 2000 mJ / cm 2 , or 50 to 1500 mJ / cm 2 The irradiation dose of ultraviolet light in step (S2) may be 10 to 2000 mJ / cm. 2 In this case, the degree of crosslinking of the crosslinked product of the first functional group-containing polymer and the first crosslinking agent can be easily adjusted to 10 to 80%.

[0154] In one embodiment of the present invention, the degree of crosslinking of the crosslinked product of the first functional group-containing polymer and the first crosslinking agent by irradiating the adhesion-promoting layer with ultraviolet light may be 10 to 80%, or 30 to 100%, or 40 to 100%, or 40 to 95%.

[0155] In particular, the crosslinked product of the first functional group-containing polymer and the first crosslinking agent may be semi-crosslinked. For example, the degree of crosslinking of the crosslinked product of the first functional group-containing polymer and the first crosslinking agent may be 10% to 80%, or 50% to 70%. When the crosslinked product of the first functional group-containing polymer and the first crosslinking agent is semi-crosslinked, the binder in the adhesion-promoting layer can be prevented from flowing or deforming. Furthermore, double bonds remain in the crosslinked product of the first functional group-containing polymer and the first crosslinking agent, allowing them to form chemical bonds with the crosslinked product of the second functional group-containing polymer and the second crosslinking agent (described below), thereby further improving the adhesive strength between the electrode active material layer and the electrode current collector.

[0156] Next, a slurry for forming an electrode active material layer, which includes an electrode active material, a second conductive material, a second functional group-containing polymer, a second crosslinking agent, and a second photoinitiator, is coated on the top surface of the resultant product of step (S2) and dried to form an electrode active material layer (S3).

[0157] For the electrode active material, the second conductive material, the second functional group-containing polymer, and the second crosslinking agent, refer to the above contents.

[0158] The second photoinitiator crosslinks the second functional group-containing polymer and the second crosslinker.

[0159] In one embodiment of the present invention, the second photoinitiator may comprise a Type 1 photoinitiator. For example, the second photoinitiator can include bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (Irgacure 819), oxide (diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide) (TPO), maleimide, 2,4,5-trimethylbenzoyl-diphenylphosphine oxide, bis(2,6-dimethyloxybenzoyl)2,4,4-trimethylpentyl)phosphine oxide, propanone, oligo(2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone, hydroxy-2-methyl-1-phenylpropan-1-one, oxide, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure 2959), or two or more thereof.

[0160] In one embodiment of the present invention, the second photoinitiator may further include a Type 2 photoinitiator in addition to the Type 1 photoinitiator. When the Type 2 photoinitiator is further included, crosslinking efficiency can be further improved. Examples of the Type 2 photoinitiator include benzophenone, benzophenone derivatives, camphorquinone, Michler's ketone, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-methylpropyl)ketone, benzil dimethyl ketal, 2-benzyl-2-N,N-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-mercaptobenzoxazole, camphorquinone, 2-hydroxy-2-ketyl-1-(4-t-butyl)phenylpropan-1-one, 2-methyl-1-[4-(methylthiophenyl)-2-morpholinopropanone], thioxanthone, thioxanthone derivatives, or two or more thereof.

[0161] Examples of the benzophenone derivatives include hydroxyacetophenone, 4-methylbenzophenone, 4-phenylbenzophenone, 4,4'-dimethylaminobenzophenone, 4,4'-bis(diethylamino)benzophenone, 4-methoxybenzophenone, 4,4'-dimethoxybenzophenone, 4,4'-dimethylbenzophenone, 4,4'-dichlorobenzophenone, 2,4,6-trimethylbenzophenone, 4-(4-methylthiophenyl)benzophenone, 3,3'-dimethyl-4-methoxybenzophenone, methyl-2-benzoylbenzoate, 4-(2-hydroxyethoxy)benzophenone, 4-methyl-2-benzoylbenzoate ...

[0039] Examples of suitable benzophenones include, but are not limited to, 4-(13-acryloyl-1,4,7,10,13-pentaoxatridecyl)-benzophenone, 4-benzoyl-N,N-dimethyl-N-[2-(1-oxo-2-propenyl)oxy]ethyl-benzenemethanaminium chloride, 2-hydroxy-3-(4-benzoylphenoxy)-N,N,N-trimethyl-propanaminium chloride monohydrate, 4-hydroxybenzophenone, 4-(13-acryloyl-1,4,7,10,13-pentaoxatridecyl)-benzophenone, 4-benzoyl-N,N-dimethyl-N-[2-(1-oxo-2-propenyl)oxy]ethyl-benzenemethanaminium chloride, and the like.

[0162] Examples of the thioxanthone derivatives include 2-isopropylthioxanthone, 2-chlorothioxanthone, 2-dodecylthioxanthone, 2,4-diethylthioxanthone, 2,4-dimethylthioxanthone, 1-methoxycarbonylthioxanthone, 2-ethoxycarbonylthioxanthone, 3-(2-methoxyethoxycarbonyl)-thioxanthone, 4-butoxycarbonyl-thioxanthone, and 3-butoxycarbonyl-7-methylthioxanthone. Thioxanthone, 1-cyano-3-chlorothioxanthone, 1-ethoxycarbonyl-3-chlorothioxanthone, 1-ethoxycarbonyl-3-ethoxythioxanthone, 1-ethoxycarbonyl-3-aminothioxanthone, 1-ethoxycarbonyl-3-phenylsulfurylthioxanthone, 3,4-di[2-(2-methoxyethoxy)ethoxycarbonyl]thioxanthone, 1-ethoxycarbonyl-3-(1-methyl-1-morpholino) -ethyl)-thioxanthone, 2-methyl-6-dimethoxymethyl-thioxanthone, 2-methyl-6-(1,1-dimethoxy-benzyl)-thioxanthone, 2-morpholinomethylthioxanthone, 2-methyl-6-morpholinomethyl-thioxanthone, N-allylthioxanthone-3,4-dicarboximide, N-octylthioxanthone-3,4-dicarboximide, N-(1,1,3,3-tetramethylbutyl)-thioxanthone- Examples of suitable thioxanthone derivatives include, but are not limited to, 3,4-dicarboximide, 1-phenoxythioxanthone, 6-ethoxycarbonyl-2-methoxythioxanthone, 6-ethoxycarbonyl-2-methylthioxanthone, thioxanthone-2-polyethylene glycol ester, and 2-hydroxy-3-(3,4-dimethyl-9-oxo-9H-thioxanthone-2-yloxy)-N,N,N-trimethyl-1-propanaminium chloride.

[0163] In one embodiment of the present invention, the content of the second photoinitiator may be greater than the content of the first photoinitiator. When the thickness of the electrode active material layer is greater than the thickness of the adhesion promotion layer, the content of the second photoinitiator may be greater than the content of the first photoinitiator.

[0164] The content of the second photoinitiator may be 0.05 to 20 wt%, or 0.07 to 10 wt%, or 0.1 to 5 wt%, based on 100 wt% of the total weight of the second functional group-containing polymer and the second crosslinking agent. When the content of the second photoinitiator satisfies this range, the crosslinking reaction is sufficiently carried out, making it easier to ensure a desired degree of crosslinking.

[0165] In one embodiment of the present invention, the electrode active material layer forming slurry can be prepared by adding a second conductive material to a dispersion medium to pre-disperse the material, and then adding and mixing the electrode active material, the second functional group-containing polymer, and the second crosslinking agent.

[0166] The dispersion medium is not particularly limited as long as it can dissolve the second photoinitiator and the second crosslinking agent and disperse the second conductive material. The dispersion medium may include, for example, alcohols such as ethanol, isopropyl alcohol (IPA), and n-propyl alcohol; ketones such as acetone and methyl ethyl ketone (MEK); propyl acetate; N-methyl-2-pyrrolidone; dimethylformamide; dimethylacetamide; water; or two or more of these.

[0167] In one embodiment of the present invention, the electrode active material layer forming slurry may further include a dispersant, such as polyvinylpyrrolidone, hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), ethylhydroxyethyl cellulose (EHEC), methyl cellulose (MC), carboxymethyl cellulose (CMC), hydroxyalkyl methyl cellulose, cyanoethylene polyvinyl alcohol, or two or more thereof.

[0168] In one embodiment of the present invention, step (S3) may include the steps of: coating the slurry for forming an electrode active material layer on an upper surface of the resultant of step (S2), drying, and then irradiating with ultraviolet light to form a first electrode active material layer; and coating the slurry for forming an electrode active material layer on the first electrode active material layer, and drying, to form a second electrode active material layer.

[0169] If the electrode active material layer forming slurry is coated all at once and then irradiated with ultraviolet light, the ultraviolet light may not reach the vicinity of the interface of the electrode active material layer that contacts the adhesion-promoting layer effectively, and therefore the second functional group-containing polymer and the second crosslinking agent may not be crosslinked effectively near the interface of the electrode active material layer that contacts the adhesion-promoting layer.

[0170] The electrode active material layer-forming slurry is coated on the upper surface of the adhesion-promoting layer, dried, and then irradiated with ultraviolet light to form a first electrode active material layer.The electrode active material-forming slurry is then coated again on the first electrode active material layer and dried, and the second functional group-containing polymer and the second crosslinking agent can be easily crosslinked even near the interface of the electrode active material layer that contacts the adhesion-promoting layer.

[0171] In one embodiment of the present invention, the loading amount of the electrode active material layer forming slurry for forming the first electrode active material layer is 2 to 7 mAh / cm 2 , or 2.5 to 6 mAh / cm 2 When the loading amount of the electrode active material layer-forming slurry satisfies the above range, ultraviolet light can reach the vicinity of the interface of the first electrode active material layer in contact with the adhesion-promoting layer, and therefore the second functional group-containing polymer and the second crosslinking agent can be more easily crosslinked also in the vicinity of the interface of the electrode active material layer in contact with the adhesion-promoting layer.

[0172] The electrode active material layer forming slurry may be coated using a common method commonly used in the art, such as a spray coating method.

[0173] In one embodiment of the present invention, the drying can be performed by a conventional drying method used in electrode manufacturing. For example, the drying can be performed at 30°C to 100°C, or 40°C to 80°C. The drying can be performed in air for 3 to 45 seconds, or 5 to 40 seconds.

[0174] Next, the result of step (S3) is irradiated with ultraviolet light (S4). By irradiating the electrode active material layer with ultraviolet light, the second functional group-containing polymer and the second crosslinking agent can be crosslinked.

[0175] In one embodiment of the present invention, the irradiation dose of ultraviolet light in step (S4) is 200 to 10,000 mJ / cm 2 , or 500 to 8,000 mJ / cm 2 It could be.

[0176] In one embodiment of the present invention, by irradiating the electrode active material layer with ultraviolet light, the crosslinked product of the first functional group-containing polymer and the first crosslinking agent in the adhesion-promoting layer and the crosslinked product of the second functional group-containing polymer and the second crosslinking agent in the electrode active material layer can form a chemical bond with each other. For example, the crosslinked product of the first functional group-containing polymer and the first crosslinking agent can crosslink with the crosslinked product of the second functional group-containing polymer and the second crosslinking agent in the electrode active material layer. In this case, the adhesive strength between the electrode active material layer and the electrode current collector can be further improved.

[0177] In one embodiment of the present invention, the crosslinking degree of the crosslinked binder included in the adhesion promotion layer in the resultant product of step (S4) may be 10 to 100%, or 50 to 100%, or 10 to 95%. When the crosslinking degree of the binder satisfies this range, the stability of the adhesion promotion layer can be ensured and excellent adhesion to the electrode active material layer can be more easily ensured.

[0178] A lithium secondary battery can be manufactured by using the electrode for a lithium secondary battery according to an embodiment of the present invention together with a separator (separator).

[0179] The lithium secondary battery may include a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery.

[0180] The separator used in the lithium secondary battery according to one embodiment of the present invention is not particularly limited and may be composed of only a porous polymer substrate, or may be composed of a porous polymer substrate and an organic-inorganic composite porous layer formed on at least one surface of the porous polymer substrate and including a plurality of inorganic particles and a binder polymer. The separator is interposed between the positive electrode and the negative electrode to provide insulation between the positive electrode and the negative electrode.

[0181] The porous polymer substrate may be any porous polymer substrate commonly used in the art, including, but not limited to, a polyolefin-based porous polymer membrane or nonwoven fabric.

[0182] Examples of the polyolefin-based porous polymer membrane include polyethylene such as high-density polyethylene, linear low-density polyethylene, low-density polyethylene, and ultra-high molecular weight polyethylene, polyolefin-based polymers such as polypropylene, polybutylene, and polypentene, and membranes formed from two or more of these.

[0183] Examples of the nonwoven fabric include polyolefin-based nonwoven fabrics, as well as nonwoven fabrics made of polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyethersulfone, polyphenyleneoxide, polyphenylenesulfide, polyethylenenaphthalene, or two or more of these. The nonwoven fabric may be a spunbonded or meltblown nonwoven fabric made of long fibers.

[0184] The thickness of the porous polymer substrate is not particularly limited, but may be 3 μm to 50 μm, or 3 μm to 15 μm. The pore size and porosity of the porous polymer substrate are also not particularly limited, but may be 0.01 μm to 50 μm and 10% to 95%, respectively.

[0185] In one embodiment of the present invention, the inorganic particles are not particularly limited as long as they are electrochemically stable. That is, the inorganic particles that can be used in the present invention are those that are suitable for use in a battery operating voltage range (e.g., Li / Li + There are no particular limitations on the inorganic particles as long as they do not undergo oxidation and / or reduction reactions at a temperature (0 to 5 V relative to the reference voltage). The inorganic particles may include high-dielectric-constant inorganic particles having a dielectric constant of 5 or more or 10 or more, inorganic particles having lithium ion transfer ability, or two or more of these. Inorganic particles having a dielectric constant of 5 or more include BaTiO3, BaSO4, Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti yO3(PLZT, where 0 <x<1、0<y<1である)、Pb(Mg 1 / 3 Nb 2 / 3 )O3-PbTiO3 (PMN-PT), hafnia (HfO2), SrTiO3, SnO2, CeO2, MgO, Mg(OH)2, NiO, CaO, ZnO, ZrO2, Y2O3, SiO2, Al2O3, γ-AlOOH, Al(OH)3, SiC, TiO2, or a mixture of two or more of these can be used, but are not limited to these.

[0186] In one embodiment of the present invention, the particle size of the inorganic particles is not particularly limited, but may have an average particle size in the range of 0.01 to 10 μm or 0.05 to 1.0 μm to form an organic-inorganic composite porous layer of uniform thickness and with an appropriate porosity. In this case, the average particle size of the inorganic particles refers to the particle size at 50% of the smallest particle size (D50), calculated based on the particle size distribution of classified particles measured using a general particle size distribution analyzer. Such particle size distribution can be measured by laser diffraction analysis.

[0187] In one embodiment of the present invention, the binder polymer contained in the separator is poly(vinylidene fluoride) (PVdF), poly(vinylidene fluoride)-hexafluoropropylene, poly(vinylidene fluoride)-trichloroethylene, poly(vinylidene fluoride)-chlorotrifluoroethylene, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, ethylene-vinyl acetate copolymer, polyethylene oxide, or cellulose acetate. The polymer may include, but is not limited to, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethylpolyvinylalcohol, cyanoethyl cellulose, cyanoethylsucrose, pullulan, carboxyl methyl cellulose, acrylonitrile-styrene-butadiene copolymer, polyimide, or two or more thereof.

[0188] In one embodiment of the present invention, the ratio of inorganic particles to binder polymer contained in the separator may be 20:80 to 99.9:0.1, 50:50 to 99.5:0.5, or 70:30 to 80:20. When the ratio of inorganic particles to binder polymer is within this range, sufficient adhesive strength between the inorganic particles can be ensured while sufficient voids can be formed between the inorganic particles.

[0189] In one embodiment of the present invention, the organic-inorganic composite porous layer may have a structure in which the inorganic particles are packed and in contact with each other and bound to each other by the binder polymer, thereby forming interstitial volumes between the inorganic particles, and the interstitial volumes between the inorganic particles become voids to form pores.

[0190] In an embodiment of the present invention, the lithium secondary battery includes an electrolyte solution, which may include an organic solvent and a lithium salt. The electrolyte solution may be an organic solid electrolyte or an inorganic solid electrolyte.

[0191] Examples of the organic solvent that can be used include aprotic organic solvents such as N-methyl-2-pyrrolidone, ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, 1,2-dimethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphate triester, trimethoxymethane, dioxolane derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-ibidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ethers, methyl propionate, and ethyl propionate.

[0192] The lithium salt is easily soluble in the organic solvent, and examples thereof include LiCl, LiBr, LiI, LiClO4, LiBF4, and LiB 10 Cl 10 , LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, CF3SO3Li, (CF3SO2)2NLi, lithium chloroborane, lithium lower aliphatic carboxylates, lithium 4-phenylborate, imides, etc. can be used.

[0193] In addition, to the electrolyte solution, for example, pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinoneimine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, aluminum trichloride, etc. may be added to improve charge / discharge characteristics, flame retardancy, etc. In some cases, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride may be further added to impart non-flammability, and carbon dioxide gas may be further added to improve high-temperature storage properties.

[0194] Examples of the organic solid electrolyte that can be used include polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphate ester polymers, polyagitation lysine, polyester sulfide, polyvinyl alcohol, poly(vinylidene fluoride), and polymers containing ionic dissociative groups.

[0195] Examples of the inorganic solid electrolyte that can be used include nitrides, halides, and sulfates of Li, such as LiN, LiI, LiNI, LiN-LiI-LiOH, LiSiO, LiSiO-LiI-LiOH, LiSiS, LiSiO, LiSiO-LiI-LiOH, and LiPO-LiS-SiS.

[0196] The electrolyte injection can be performed at an appropriate step in the battery manufacturing process depending on the manufacturing process and required properties of the final product, i.e., before battery assembly or at the final step of battery assembly.

[0197] The shape of the lithium secondary battery is not particularly limited, but may be a cylindrical shape using a can, a square shape, a pouch shape, or a coin shape.

[0198] The present invention will be described in detail below with reference to examples to aid in understanding the present invention. However, the examples according to the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the following examples. The examples of the present invention are provided to more completely explain the present invention to those skilled in the art. [Example]

[0199] Example 1 1.5 g of multi-walled carbon nanotubes (MWCNT) as a first conductive material and 0.3 g of polyvinylpyrrolidone (molecular weight 40,000) as a dispersant were added to 98.3 g of a dispersion medium made by mixing propyl acetate and n-propyl alcohol at a ratio of 60:40, and the mixture was pre-dispersed using a planetary mixer, followed by using a high-pressure disperser to prepare a pre-dispersion liquid of the first conductive material.

[0200] To the prepared first conductive material pre-dispersion, 1 g of UC-102M as a first functional group-containing polymer, 0.9 g of 1,12-dodecanediol dimethacrylate (SR262) as a first crosslinking agent, and 0.1 g of Irgacure 819 as a first photoinitiator were added, and then mixed in a planetary mixer to prepare a composition for forming an adhesion promoting layer. This was coated on aluminum foil (thickness 20 μm) to a thickness of 0.5 μm after drying of the adhesion promoting layer, and then dried. This was then irradiated with ultraviolet light at 50 mJ / cm. 2By irradiating the adhesion-promoting layer with light, the degree of crosslinking of the crosslinked product between the first functional group-containing polymer and the first crosslinking agent contained in the adhesion-promoting layer was set to 50%.

[0201] 1.5 g of multi-walled carbon nanotubes (MWCNT) as a second conductive material and 0.3 g of polyvinylpyrrolidone (molecular weight 40,000) as a dispersant were added to 98.2 g of a dispersion medium made by mixing propyl acetate and n-propyl alcohol at a ratio of 60:40, and the mixture was pre-dispersed using a planetary mixer, followed by using a high-pressure disperser to prepare a pre-dispersion of the second conductive material.

[0202] To the second conductive material pre-dispersion solution, 96.2 g of NCMA (Li[Ni.Co.Mn.Al]O2) as the positive electrode active material, 1 g of UC-102M as the second functional group-containing polymer, 0.9 g of 1,12-dodecanediol dimethacrylate (SR262) as the second crosslinker, and 0.1 g of Irgacure 819 as the second photoinitiator were added, resulting in a weight ratio of NCMA:second conductive material:mixture of the second functional group-containing polymer and the second crosslinker (excluding the dispersant) of 96.2:1.5:2.0. The mixture was then mixed in a planetary mixer to prepare a slurry for forming an electrode active material layer.

[0203] The prepared slurry for forming the electrode active material layer was coated on the upper surface of the adhesion promoting layer, dried, and then exposed to ultraviolet light of 8,000 mJ / cm 2 The electrode for a lithium secondary battery was produced by irradiating the electrode with light.

[0204] Example 2 1.5 g of multi-walled carbon nanotubes (MWCNT) as a first conductive material and 0.3 g of polyvinylpyrrolidone (molecular weight 40,000) as a dispersant were added to 98.3 g of a dispersion medium made by mixing propyl acetate and n-propyl alcohol in a ratio of 60:40, and the mixture was pre-dispersed using a planetary mixer, followed by using a high-pressure disperser to prepare a pre-dispersion liquid of the first conductive material.

[0205] An adhesion-promoting layer-forming composition was prepared in the same manner as in Example 1, except that 1.2 g of an acrylic-modified polyurethane resin (weight-average molecular weight: 110,000) represented by the following chemical formula 1, 1.1 g of an acrylic-modified polyethylene glycol resin (weight-average molecular weight: 10,000) represented by the following chemical formula 3, and 0.2 g of Irgacure 819 as a photoinitiator were used in the first conductive material preliminary dispersion liquid prepared above, and an adhesion-promoting layer-forming composition was formed on a current collector. [ka] In the above Chemical Formula 1, n is 8 (5 to 20), and m is 20 (10 to 30). [ka] In the above Chemical Formula 3, q ​​is 200 (150 to 250).

[0206] Thereafter, a slurry for forming an electrode active material layer was prepared in the same manner as in Example 1, except that the prepared current collector with the adhesion-promoting layer formed thereon was used. The slurry was then coated on the upper surface of the adhesion-promoting layer, dried, and then exposed to ultraviolet light at 8000 mJ / cm. 2 The electrode for a lithium secondary battery was produced by irradiating the electrode with light.

[0207] Comparative Example 1 1.5 g of single-walled carbon nanotubes (MWCNT) as a conductive material and 0.3 g of polyvinylpyrrolidone (molecular weight 40,000) as a dispersant were added to 98.3 g of a dispersion medium made by mixing propyl acetate and n-propyl alcohol in a ratio of 60:40, and the mixture was pre-dispersed using a planetary mixer, followed by a high-pressure disperser to prepare a conductive material pre-dispersion liquid.

[0208] To the prepared conductive material pre-dispersion, 96.2 g of NCMA (Li[Ni.Co.Mn.Al]O2) as the positive electrode active material, 1 g of UC-102M as the functional group-containing polymer, 0.9 g of 1,12-dodecanediol dimethacrylate (SR262) as the crosslinker, and 0.1 g of Irgacure 819 as the photoinitiator were added, resulting in a weight ratio of NCMA:conductive material:functional group-containing polymer and crosslinker mixture of 96.5:1.5:2.0. This was then mixed in a planetary mixer to prepare a slurry for forming an electrode active material layer.

[0209] The prepared electrode active material layer forming slurry was coated on an aluminum foil (thickness: 20 μm), dried, and then exposed to ultraviolet light at 8000 mJ / cm 2 The electrode for a lithium secondary battery was produced by irradiating the electrode with light.

[0210] Comparative Example 2 An electrode for a lithium secondary battery was produced in the same manner as in Comparative Example 1, except that the weight ratio of NCMA:conductive material:mixture of functional group-containing polymer and second crosslinking agent was 94.5:1.5:4.0.

[0211] Comparative Example 3 NCMA (Li[Ni.Co.Mn.Al]O2) as a positive electrode active material, 1.5 g of single-walled carbon nanotubes (MWCNT) as a conductive material, and poly(vinylidene fluoride) as a binder were added to N-methyl-2-pyrrolidone (NMP) in a weight ratio of 96.5:1.5:2.0 and mixed to prepare a slurry for forming an electrode active material layer.

[0212] The prepared electrode active material layer forming slurry was coated on an aluminum foil (thickness: 20 μm) and dried to prepare an electrode for a lithium secondary battery.

[0213] Evaluation example: Checking the chemical bond between the first binder and the second binder In the electrode produced in Example 2, the presence of a chemical bond between the first binder in the adhesion promoting layer and the second binder in the electrode active material layer was confirmed using an infrared spectrometer (Agilent Cary 630 FT-IR), and the results are shown in Figure 2.

[0214] Referring to FIG. 2, for this evaluation, an adhesion promoting layer was formed on a current collector according to Example 2, and then irradiated with ultraviolet light. Then, the upper surface of the adhesion promoting layer irradiated with ultraviolet light was coated with a slurry for forming an electrode active material layer, and dried to form an electrode active material layer. The amount of ultraviolet light irradiated thereto was 0 mJ / cm. 2 , 4200mJ / cm 2 , 8000mJ / cm 2 By changing the temperature, three types of electrodes were finally prepared.

[0215] Thereafter, the electrode active material layer was removed from each of the prepared electrodes with single-sided tape to prepare a sample in which the adhesion promoting layer was exposed. For this sample, an infrared spectrometer (Agilent Cary 630 FT-IR) was used to measure the peak at 1633 cm , which is the peak of the carbon-carbon double bond (C═C) of the first binder contained in the adhesion promoting layer. -1 The change in the peak at the initial UV dose of 0 mJ / cm 2 In the case of 8000 mJ / cm , the peak of the carbon-carbon double bond (C=C) was clearly observed, but the amount of ultraviolet light increased to 8000 mJ / cm . 2 It was found that the peak of the double bond (C=C) was significantly reduced when the irradiance was 8000 mJ / cm 2 as in Example 2, as compared with immediately after the electrode active material layer was formed on the upper surface of the adhesion-promoting layer in Example 2 (before UV irradiation). 2 When the sample was irradiated with ultraviolet light, the peak of the double bond (C=C) was found to be significantly reduced, which confirmed that the double bond of the first binder in the adhesion-promoting layer disappeared and a chemical bond with the second binder was formed.

[0216] Evaluation example: Measurement of electrode adhesive strength and initial capacity The thickness of the electrodes for lithium secondary batteries produced in Examples 1 and 2 and Comparative Examples 1 to 3, the adhesive strength between the electrode active material layer and the electrode current collector, and the initial capacity were measured and are shown in Table 1 below.

[0217] The adhesive strength between the electrode active material layer and the electrode current collector was measured by attaching and fixing the electrode to a slide glass, and then peeling the electrode current collector from the electrode active material layer at an angle of 180° at 25°C at a speed of 1.0 mm / s using a peel strength measuring device (UTA-500N).

[0218] After the cell was manufactured, the initial capacity of the electrode was measured by charging and discharging at 25°C and 0.1 C from 2.5 V to 4.25 V.

[0219] [Table 1]

[0220] As can be seen from Table 1, Examples 1 and 2 were provided with an adhesion-promoting layer containing a cross-linking binder, and therefore, even when the electrode active material layer contained a cross-linking binder, the adhesive strength between the electrode active material layer and the electrode current collector and the initial capacity level were almost the same as those of a conventional lithium secondary battery electrode prepared using N-methyl-2-pyrrolidone as a solvent. On the other hand, Comparative Example 1 was not provided with an adhesion-promoting layer, and therefore, when the electrode active material layer contained a cross-linking binder, the adhesive strength between the electrode active material layer and the electrode current collector was not sufficiently ensured.

[0221] In Comparative Example 2, it was confirmed that when the electrode active material layer contained an excessive amount of crosslinked binder, the adhesive strength between the electrode active material layer and the electrode current collector could not be sufficiently ensured, and this rather led to a decrease in the initial capacity.

[0222] In Comparative Example 3, it was confirmed that when a non-crosslinked binder was contained in the electrode active material layer without providing an adhesion promoting layer, sufficient adhesive strength could not be ensured between the electrode active material layer and the electrode current collector. [Explanation of symbols]

[0223] 1. Electrodes for lithium secondary batteries 10 Electrode current collector 20 Adhesion promotion layer 30 Electrode active material layer

Claims

1. an electrode current collector; an adhesion promoting layer located on at least one surface of the electrode current collector, the adhesion promoting layer including a first binder and a first conductive material; an electrode active material layer located on an upper surface of the adhesion promotion layer and including an electrode active material, a second conductive material, and a second binder; Including, the first binder and the second binder each contain a binder polymer having a crosslinked structure, The electrode for a lithium secondary battery, wherein the first binder and the second binder form bridges with each other.

2. 2. The electrode for a lithium secondary battery according to claim 1, wherein the first binder comprises a crosslinked product of a first functional group-containing polymer and a first crosslinking agent.

3. 3. The electrode for a lithium secondary battery according to claim 2, wherein the first functional group-containing polymer contains a repeating unit derived from an isoprene monomer, a repeating unit derived from a butadiene monomer, a repeating unit derived from a cyclopentadiene monomer, a repeating unit derived from an ethylidene norbornene monomer, a repeating unit derived from a vinyl norbornene monomer, or two or more of these.

4. 3. The electrode for a lithium secondary battery according to claim 2, wherein the functional group comprises a carboxyl group, a (meth)acrylate group, a vinyl group, a vinyl ether group, an epoxy group, or two or more of these.

5. 3. The electrode for a lithium secondary battery according to claim 2, wherein the first cross-linking agent comprises a monofunctional (meth)acrylate, a difunctional (meth)acrylate, a polyfunctional (meth)acrylate, or two or more of these.

6. 3. The electrode for a lithium secondary battery according to claim 2, wherein the first cross-linking agent comprises a linear or branched alkyl(meth)acrylate, a cyclic(meth)acrylate, an aromatic(meth)acrylate, or two or more of these.

7. 3. The electrode for a lithium secondary battery according to claim 2, wherein the first crosslinking agent comprises 2-ethylhexyl acrylate, isostearyl acrylate, dicyclopentanyl acrylate, n-vinyl caprolactam, phenoxyethyl (meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-hexanediol di(meth)acrylate, tricyclodecane dimethanol diacrylate, isobornyl acrylate, polyethylene glycol diacrylate, 1,12-dodecanediol dimethacrylate, or two or more thereof.

8. 3. The electrode for a lithium secondary battery according to claim 2, wherein a weight ratio of the first functional group-containing polymer to the first crosslinking agent is 10:90 to 90:

10.

9. 2. The electrode for a lithium secondary battery according to claim 1, wherein the first binder comprises an acrylic-modified polyurethane resin, an acrylic-modified polyethylene glycol resin, or a crosslinked product of both.

10. 2. The electrode for a lithium secondary battery according to claim 1, wherein the second binder comprises a crosslinked product of a second functional group-containing polymer and a second crosslinking agent.

11. 11. The electrode for a lithium secondary battery according to claim 10, wherein the second functional group-containing polymer contains a repeating unit derived from an isoprene monomer, a repeating unit derived from a butadiene monomer, a repeating unit derived from a cyclopentadiene monomer, a repeating unit derived from an ethylidene norbornene monomer, a repeating unit derived from a vinyl norbornene monomer, or two or more of these.

12. 11. The electrode for a lithium secondary battery according to claim 10, wherein the functional group comprises a carboxyl group, a (meth)acrylate group, a vinyl group, a vinyl ether group, an epoxy group, or two or more of these.

13. 11. The electrode for a lithium secondary battery according to claim 10, wherein the second cross-linking agent comprises a monofunctional (meth)acrylate, a difunctional (meth)acrylate, a polyfunctional (meth)acrylate, or two or more of these.

14. 11. The electrode for a lithium secondary battery according to claim 10, wherein the second crosslinking agent comprises a linear or branched alkyl(meth)acrylate, a cyclic (meth)acrylate, an aromatic (meth)acrylate, or two or more of these.

15. 11. The electrode for a lithium secondary battery according to claim 10, wherein the second crosslinker comprises 2-ethylhexyl acrylate, isostearyl acrylate, dicyclopentanyl acrylate, n-vinyl caprolactam, phenoxyethyl (meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-hexanediol di(meth)acrylate, tricyclodecane dimethanol diacrylate, isobornyl acrylate, polyethylene glycol diacrylate, 1,12-dodecanediol dimethacrylate, or two or more thereof.

16. 11. The electrode for a lithium secondary battery according to claim 10, wherein the weight ratio of the second functional group-containing polymer to the second crosslinking agent is 10:90 to 90:

10.

17. 2. The electrode for a lithium secondary battery according to claim 1, wherein the content of the second binder is 1.5 to 3.5% by weight based on 100% by weight of the electrode active material layer.

18. 2. The electrode for a lithium secondary battery according to claim 1, wherein the content of the first binder is 2 to 70% by weight based on 100% by weight of the adhesion promoting layer.

19. 2. The electrode for a lithium secondary battery according to claim 1, wherein the content of the first conductive material is 0.1 to 10% by weight based on 100% by weight of the adhesion promoting layer.

20. 2. The electrode for a lithium secondary battery according to claim 1, wherein the electrode for a lithium secondary battery is a positive electrode.

21. (S1) forming an adhesion promotion layer by coating an electrode current collector with a composition for forming an adhesion promotion layer, the composition including a first functional group-containing polymer, a first crosslinking agent, a first photoinitiator, and a first conductive material, and drying the composition; (S2) irradiating the adhesion promoting layer with ultraviolet light; (S3) forming an electrode active material layer by coating an electrode active material layer-forming slurry containing an electrode active material, a second conductive material, a second functional group-containing polymer, a second crosslinking agent, and a second photoinitiator on the upper surface of the resultant product of step (S2) and drying the coating; and (S4) irradiating the result of step (S3) with ultraviolet light; Including, the crosslinking degree of the crosslinked product of the first functional group-containing polymer and the first crosslinking agent resulting from step (S2) is 10 to 80%; a crosslinked product of the first functional group-containing polymer and the first crosslinking agent and a crosslinked product of the second functional group-containing polymer and the second crosslinking agent are crosslinked with each other.

22. 22. The method of claim 21, wherein the crosslinked binder contained in the adhesion promoting layer in the resultant product of step (S4) has a crosslinking degree of 10 to 100%.

23. The step (S3) coating the electrode active material layer forming slurry on the resultant of step (S2), drying the resultant, and then irradiating the resultant with ultraviolet light to form a first electrode active material layer; and coating the electrode active material layer forming slurry on the first electrode active material layer and drying the slurry to form a second electrode active material layer.

24. 22. The method for producing an electrode for a lithium secondary battery according to claim 21, wherein the first photoinitiator comprises a Type 1 photoinitiator.

25. 25. The method for producing an electrode for a lithium secondary battery according to claim 24, wherein the first photoinitiator further comprises a Type 2 photoinitiator.

26. 22. The method for producing an electrode for a lithium secondary battery according to claim 21, wherein the first photoinitiator comprises bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, oxide (diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide) (TPO), maleimide, 2,4,5-trimethylbenzoyl-diphenylphosphine oxide, bis(2,6-dimethyloxybenzoyl)2,4,4-trimethylpentyl)phosphine oxide, propanone, oligo(2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone, hydroxy-2-methyl-1-phenylpropan-1-one, oxide, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, or two or more thereof.

27. 22. The method for manufacturing an electrode for a lithium secondary battery according to claim 21, wherein a content of the first photoinitiator is 0.05 to 15 wt % based on 100 wt % of the total weight of the first functional group-containing polymer and the first crosslinking agent.

28. 22. The method for producing an electrode for a lithium secondary battery according to claim 21, wherein the second photoinitiator comprises a Type 1 photoinitiator.

29. 29. The method for producing an electrode for a lithium secondary battery according to claim 28, wherein the second photoinitiator further comprises a Type 2 photoinitiator.

30. 22. The method for producing an electrode for a lithium secondary battery according to claim 21, wherein the second photoinitiator comprises bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, oxide (diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide) (TPO), maleimide, 2,4,5-trimethylbenzoyl-diphenylphosphine oxide, bis(2,6-dimethyloxybenzoyl)2,4,4-trimethylpentyl)phosphine oxide, propanone, oligo(2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone, hydroxy-2-methyl-1-phenylpropan-1-one, oxide, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, or two or more thereof.

31. 22. The method for manufacturing an electrode for a lithium secondary battery according to claim 21, wherein the content of the second photoinitiator is 0.05 to 20 wt % based on 100 wt % of the total weight of the second functional group-containing polymer and the second crosslinking agent.

32. In the step (S2), the amount of ultraviolet light irradiation is 10 to 2,000 mJ / cm ２ The method for producing an electrode for a lithium secondary battery according to claim 21,

33. In the step (S4), the amount of ultraviolet light irradiation is 200 to 10,000 mJ / cm ２ The method for producing an electrode for a lithium secondary battery according to claim 21,

34. A lithium secondary battery comprising the electrode for a lithium secondary battery according to any one of claims 1 to 20.

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