Lithium secondary battery separator, manufacturing method thereof, lithium secondary battery comprising same and manufacturing method thereof

Abstract

The present invention provides a lithium secondary battery separator, comprising: a porous polymer substrate; at least one inorganic coating layer which is provided on at least one surface of the porous polymer substrate and comprises inorganic particles and a first particulate binder polymer; and at least one adhesive layer which is provided on at least one surface of the inorganic coating layer and comprises a second particulate binder polymer and a non-particulate binder precursor, wherein the non-particulate binder precursor comprises an acrylic monomer or oligomer.

Description

Separator for lithium secondary battery and method for manufacturing same, lithium secondary battery including same and method for manufacturing same

[0001] The present invention relates to a separator for a lithium secondary battery and a method for manufacturing the same, and a lithium secondary battery including the same and a method for manufacturing the same.

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0104338, filed August 6, 2024, the entire contents of which are incorporated herein by reference.

[0003]

[0004] Non-aqueous secondary batteries, such as lithium secondary batteries, are widely used as power sources for portable electronic devices such as laptops, mobile phones, digital cameras, and camcorders, as well as electric vehicles.

[0005] The fundamental requirements for separators in lithium secondary batteries are to electrically isolate the positive and negative electrodes, while simultaneously enhancing ionic conductivity by enhancing the permeability of ions, such as lithium ions, through high porosity. While these separators themselves do not participate in the electrochemical reactions of secondary batteries, their physical properties, such as wettability to electrolytes, porosity, and thermal shrinkage, significantly impact the performance and safety of the battery.

[0006] Membranes using porous polymer substrates can experience shrinkage at high temperatures, causing internal short circuits. Furthermore, the polymer membrane substrate can melt during thermal runaway, increasing the risk of ignition. Therefore, to address these shortcomings, an inorganic coating layer can be added to one or both sides of the porous polymer substrate, and inorganic particles and a binder polymer that can address these shortcomings can be added to the inorganic coating layer.

[0007] Meanwhile, the binder polymer swells after being immersed in the electrolyte, resulting in a deterioration in its physical properties. Consequently, the coating layer comprising the binder polymer may experience reduced adhesion to porous polymer substrates, thereby reducing its ability to suppress thermal shrinkage of the separator. Furthermore, the reduced adhesion to the electrodes may result in problems such as folding of the separator or poor appearance of the manufactured cell.

[0008]

[0009] The present invention was invented to solve the above-described problems, and specifically, the purpose is to provide a separator for a lithium secondary battery that has excellent air permeability and resistance characteristics, while ensuring stability in an electrolyte solution and having excellent electrode adhesion (wet adhesion) after electrolyte impregnation.

[0010] Meanwhile, the technical problem to be solved by the present invention is not limited to the above purpose, and also includes other problems that can be clearly understood by those skilled in the art from the detailed description of the specification.

[0011]

[0012] To achieve this purpose, according to one aspect of the present invention, a separator for a lithium secondary battery, a method for manufacturing the same, a lithium secondary battery and a method for manufacturing the same are provided according to the following embodiments.

[0013] According to a first embodiment, a separator for a lithium secondary battery is provided, comprising: a porous polymer substrate; at least one inorganic coating layer formed on at least one surface of the porous polymer substrate, the inorganic coating layer including inorganic particles and a first particulate binder polymer; and at least one adhesive layer formed on at least one surface of the inorganic coating layer, the adhesive layer including a second particulate binder polymer and a non-particulate binder precursor; wherein the non-particulate binder precursor includes an acrylic monomer or oligomer.

[0014] According to a second embodiment, in the first embodiment, the non-particulate binder precursor may include a thermally polymerizable acrylic monomer, a thermally polymerizable acrylic oligomer, a photopolymerizable acrylic monomer, a photopolymerizable acrylic oligomer, or two or more thereof.

[0015] According to a third embodiment, in any one of the first to second embodiments, the non-particulate binder precursor may be polymerized under conditions of a temperature of 45°C to 85°C to form a non-particulate binder polymer.

[0016] According to a fourth embodiment, in any one of the first to third embodiments, the acrylic monomer or oligomer is butyl acrylate, β-carboxyethylacrylate, 2-ethylhexylacrylate, 2-methoxyethylacrylate, 4-hydroxybutylacrylate, ethylacrylate, 2-hydroxyethylacrylate, 2-hydroxypropyl acrylate, pentylmethacrylate, 2-hydroxymethylacrylate, ethylmethacrylate, It may be an oligomer containing one or more monomers selected from methylmethacrylate, acrylic acid, and acrylonitrile, or one or more repeating units derived therefrom.

[0017] According to a fifth embodiment, in any one of the first to fourth embodiments, the weight ratio of the second particulate binder polymer and the non-particulate binder precursor may be 90:10 to 10:90.

[0018] According to a sixth embodiment, in any one of the first to fifth embodiments, at least a portion of the second particulate binder polymer may be connected by the non-particulate binder precursor.

[0019] According to a seventh embodiment, in any one of the first to sixth embodiments, the weight ratio of the first particle-type binder polymer and the second particle-type binder polymer may be 90:10 to 10:90.

[0020] According to an eighth embodiment, a method for manufacturing a separator for a lithium secondary battery is provided, comprising: preparing a first slurry composition comprising inorganic particles, a first particulate binder polymer, and a first solvent, and a second slurry composition comprising a second particulate binder polymer, a non-particulate binder precursor, and a second solvent; applying the first slurry composition onto at least one surface of a porous polymer substrate and first drying the same to form an inorganic coating layer; and applying the second slurry composition onto the inorganic coating layer and second drying the same to form an adhesive layer; and polymerizing the non-particulate binder precursor into a non-particulate binder polymer.

[0021] According to the ninth embodiment, in the eighth embodiment, the polymerizing step may be performed at a temperature of 45°C to 85°C.

[0022] According to a tenth embodiment, in any one of the eighth to ninth embodiments, the second drying step of forming an adhesive layer may be performed at a temperature lower than the temperature at which the non-particulate binder precursor is polymerized into a non-particulate binder polymer.

[0023] According to an eleventh embodiment, a lithium secondary battery is provided, comprising: a positive electrode; a negative electrode; an electrolyte; and a separator interposed between the positive electrode and the negative electrode; wherein the separator comprises: a porous polymer substrate; at least one inorganic coating layer formed on at least one surface of the porous polymer substrate and including inorganic particles and a first particulate binder polymer; and at least one adhesive layer formed on at least one surface of the inorganic coating layer and including a second particulate binder polymer and a non-particulate binder polymer; wherein the non-particulate binder polymer is formed by polymerizing a non-particulate binder precursor including an acrylic monomer or oligomer.

[0024] According to the 12th embodiment, in the 11th embodiment, the separator may have an electrode adhesion (wet adhesion) of 7 gf / 20 mm or more after electrolyte injection.

[0025] According to the 13th embodiment, in any one of the 11th to 12th embodiments, the solubility of the non-particulate binder polymer calculated by the following equation 1 may be 20% or less.

[0026] [Formula 1]

[0027] Solubility (%) = {(Weight measured before immersion - Weight measured after immersion) / (Weight measured before immersion)} x 100

[0028] According to the 14th embodiment, in any one of the 11th to 13th embodiments, the swelling ratio of the non-particulate binder polymer calculated by the following equation 2 may be in the range of 50% to 500%.

[0029] [Formula 2]

[0030] Swelling ratio (%) = {(Weight measured after immersion - Weight measured before immersion) / (Weight measured before immersion)} x 100

[0031] According to the 15th embodiment, in any one of the 11th to 14th embodiments, the air permeability of the separation membrane may be in the range of 40 sec / 100cc to 80 sec / 100cc.

[0032] According to a 16th embodiment, a method for manufacturing a lithium secondary battery comprising: a first electrode; a second electrode; an electrolyte; and a separator interposed between the first electrode and the second electrode, the method comprising: sequentially laminating the first electrode, the separator, and the second electrode to manufacture a laminate; laminating the laminate at a temperature of 45° C. to 85° C. for 1 to 120 seconds to manufacture an electrode assembly; and injecting an electrolyte into the electrode assembly, wherein the separator comprises: a porous polymer substrate; at least one inorganic coating layer formed on at least one surface of the porous polymer substrate, the inorganic particles, and a first particle-type binder polymer; And at least one adhesive layer formed on at least one surface of the inorganic coating layer, and including a second particle-type binder polymer and a non-particulate binder polymer; A method for manufacturing a lithium secondary battery is provided, characterized in that the non-particulate binder polymer is formed by polymerizing a non-particulate binder precursor including an acrylic monomer or oligomer.

[0033]

[0034] A separator for a lithium secondary battery according to one embodiment of the present invention has excellent air permeability and resistance characteristics, while ensuring stability in an electrolyte solution and having excellent electrode adhesion (wet adhesion) after electrolyte impregnation.

[0035] However, the effects that can be obtained through the present invention are not limited to the effects described above, and other technical effects that are not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0036]

[0037] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and serve to further understand the technical idea of ​​the present invention together with the contents of the invention described above, and therefore the present invention should not be interpreted as being limited to matters described in such drawings.

[0038] Figure 1 schematically illustrates the structure of a separation membrane according to one embodiment of the present invention.

[0039]

[0040] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0041] The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

[0042]

[0043] Justice

[0044] Throughout this specification, when it is said that a part "includes" a component, this does not mean that other components are excluded, but rather that other components may be included, unless otherwise specifically stated.

[0045] The glass transition temperature (Tg) may be a value measured, for example, by a dynamic mechanical analysis (DMA) or DSC (TA Instrument) device. For example, the glass transition temperature may be a value measured according to the DMA method specified in ASTM D4065.

[0046] D in the original specification 50 D means the particle size at the 50% point of the cumulative distribution of particle numbers according to particle size. That is, D 50 refers to the particle size at the 50% point of the cumulative distribution of particle numbers according to particle size. In addition, D 10 D means the particle size at the 10% point of the cumulative distribution of particle numbers according to particle size. 90 refers to the particle size at the 90% point of the cumulative distribution of particle numbers according to particle size.

[0047] The above particle size can be measured using the laser diffraction method. Specifically, the powder to be measured is dispersed in a dispersion medium, and then introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500), and the difference in diffraction pattern according to particle size is measured when the particles pass through the laser beam to calculate the particle size distribution. By calculating the particle diameters at points where the number of particles is 10%, 50%, and 90% of the cumulative distribution according to particle size in the measuring device, D is calculated, respectively. 10 , D 50 and D 90 can be measured.

[0048]

[0049] Separator for lithium secondary batteries

[0050] The present invention provides a separator for a lithium secondary battery.

[0051] According to one aspect of the present invention, a separator for a lithium secondary battery of the present invention comprises: a porous polymer substrate; at least one inorganic coating layer formed on at least one surface of the porous polymer substrate, the inorganic coating layer including inorganic particles and a first particle-type binder polymer; and at least one adhesive layer formed on at least one surface of the inorganic coating layer, the adhesive layer including a second particle-type binder polymer and a non-particulate binder precursor; wherein the non-particulate binder precursor is characterized in that it includes an acrylic monomer or oligomer.

[0052] Specifically, as can be seen in FIG. 1, the separator for a lithium secondary battery of the present invention comprises: a porous polymer substrate (10); an inorganic coating layer (20) formed on at least one surface of the porous polymer substrate (10); and an adhesive layer (30) formed on at least one surface of the inorganic coating layer, wherein the inorganic coating layer (20) includes inorganic particles (21) and a first particle-type binder polymer (22), and the adhesive layer (30) includes a second particle-type binder polymer (31) and a non-particle-type binder precursor (32).

[0053]

[0054] porous polymer substrate

[0055] In one embodiment of the present invention, the porous polymer substrate refers to a substrate having a plurality of pores formed therein as a porous ion-conducting barrier that allows ions to pass while blocking electrical contact between the cathode and the anode. The pores are structured to be interconnected, allowing gas or liquid to pass from one side of the substrate to the other.

[0056] The material constituting the porous polymer substrate can be any organic or inorganic material with electrical insulation properties. In particular, from the perspective of imparting a shutdown function to the porous polymer substrate, it is preferable to use a thermoplastic resin as the constituent material of the porous polymer substrate. Here, the shutdown function refers to the function of preventing thermal runaway of the battery by blocking the movement of ions by melting the thermoplastic resin and closing the pores of the porous substrate when the battery temperature rises. As the thermoplastic resin, a thermoplastic resin having a melting point of less than 200°C is suitable, and polyolefin is particularly preferred.

[0057] In addition, at least one of polymer resins such as polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyethersulfone, polyphenylene oxide, polyphenylene sulfide, and polyethylene naphthalene may be further included. The porous polymer substrate may be, but is not particularly limited to, a nonwoven fabric, a porous polymer film, or a laminate of two or more thereof.

[0058] In the present invention, the porous polymer substrate preferably has a thickness of 3 μm to 12 μm or 5 μm to 10 μm. If the thickness falls short of the above values, the conductive barrier function is insufficient, whereas if the thickness exceeds the above range (i.e., is too thick), the resistance of the separator may excessively increase.

[0059] In one embodiment of the present invention, the weight average molecular weight of the polyolefin may be 100,000 to 5,000,000. If the weight average molecular weight is less than 100,000, it may be difficult to secure sufficient mechanical properties. In addition, if it exceeds 5,000,000, the shutdown characteristics may deteriorate or molding may become difficult. In addition, the puncture strength of the porous polymer substrate may be 300 gf or more from the viewpoint of improving the manufacturing yield. The puncture strength of the porous substrate refers to the maximum puncture load (gf) measured by performing a puncture test under the conditions of a needle tip radius of 0.5 mm and a puncture speed of 4 mm / sec using a Kato tech KES-G5 handy compression tester.

[0060] In a specific embodiment of the present invention, the porous polymer substrate may be any planar porous polymer substrate used in an electrochemical device, and for example, an insulating thin film having high ion permeability and mechanical strength, a pore diameter of generally 10 nm to 200 nm, and a thickness of generally 5 ㎛ to 12 ㎛ may be used.

[0061]

[0062] Inorganic coating layer

[0063] In one embodiment of the present invention, the inorganic coating layer is formed on at least one surface of the porous polymer substrate and includes inorganic particles and a first particle-type binder polymer. The thickness of the inorganic coating layer may be in the range of 0.5 μm to 2 μm, 0.6 μm to 1.8 μm, or 0.7 μm to 1.5 μm.

[0064]

[0065] inorganic particles

[0066] The above 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 can be used within the operating voltage range of the applied electrochemical device (e.g., Li / Li).+ There are no particular limitations as long as no oxidation and / or reduction reaction occurs at a voltage of 0 to 5 V as a standard. In particular, when using inorganic particles with a high dielectric constant as inorganic particles, it can contribute to increasing the degree of dissociation of electrolyte salts, such as lithium salts, in the liquid electrolyte, thereby improving the ionic conductivity of the electrolyte.

[0067] For the reasons mentioned above, it is preferable that the inorganic particles include high-k inorganic particles having a dielectric constant of 5 or more, preferably 10 or more. Non-limiting examples of inorganic particles having a dielectric constant of 5 or more include BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT, 0 <x<1, 0<y<1), Pb(Mg 1 / 3 Nb 2 / 3 )O3-PbTiO3(PMN-PT), hafnia (HfO2), SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, SiO2, Y2O3, Al2O3, SiC, TiO2 or mixtures thereof.

[0068] In addition, inorganic particles having lithium ion transfer capability, i.e., inorganic particles containing lithium element but having the function of transferring lithium ions without storing lithium, can be used. Non-limiting examples of inorganic particles having lithium ion transfer capability include lithium phosphate (Li3PO4), lithium titanium phosphate (Li). x Ti y (PO4)3, 0 < x <2, 0 < y < 3), lithium aluminum titanium phosphate (Li x Al y Ti z (PO4)3, 0 < x < 2, 0 < y < 1, 0 < z < 3), 14Li2O-9Al2O3-38TiO2-39P2O5, etc. (LiAlTiP) x O ySeries Glass (0 <x < 4, 0 < y < 13), 리튬란탄티타네이트(Li x La y TiO3, 0 < x < 2, 0 < y < 3), Li 3.25 Ge 0.25 P 0.75 Lithium germanium thiophosphate (Li) such as S4 x Ge y P z S w , 0 < x < 4, 0 < y < 1, 0 < z < 1, 0 < w < 5), lithium nitride (Li 3 N ), etc. x N y , 0 < x < 4, 0 < y < 2), SiS2 series glasses such as Li3PO4-Li2S-SiS2 (Li x Si y S z , 0 < x < 3, 0 <y < 2, 0 < z < 4), LiI-Li2S-P2S5등과 같은 P2S5계열 글래스(Li x P y S z , 0 < x < 3, 0< y < 3, 0 < z < 7) or mixtures thereof.

[0069] In addition, the average particle diameter of the inorganic particles is not particularly limited, but in order to form a coating layer of uniform thickness and have an appropriate porosity, it is preferably in the range of 0.1 ㎛ to 2.0 ㎛, 0.2 ㎛ to 1.8 ㎛, or 0.4 ㎛ to 1 ㎛. If the average particle diameter of the inorganic particles is less than the lower limit, dispersibility may be reduced, and if it exceeds the upper limit, the thickness of the inorganic coating layer formed may increase.

[0070] In one embodiment of the present invention, the inorganic particles may be included in a range of 10 wt% to 90 wt% relative to 100 wt% of the inorganic coating layer.

[0071]

[0072] First particle-type binder polymer

[0073] In one embodiment of the present invention, the first particle-type binder polymer may have a property of maintaining its original particle shape without being deformed even when dispersed in a solvent. Specifically, the first particle-type binder polymer may mean that it exists in a particle state in an aqueous solvent. Specifically, the first particle-type binder polymer may mean that it has low solubility in an aqueous solvent and thus has a form that is dispersed in a particle form in the aqueous solvent. The first particle-type binder polymer may have an aspect ratio in the aqueous solvent within a range of 1.0 to 1.5, 1.0 to 1.3, or 1.0 to 1.2. Here, the aspect ratio is defined as the ratio of the length of the major axis to the minor axis of the first particle-type binder, and the closer it is to 1, the closer it is to a sphere. The aspect ratio can be calculated, for example, using a particle shape analyzer (QICPIC-LIXELL, Sympatec GmbH).

[0074] In one embodiment of the present invention, the first particle-type binder polymer may be a first acrylic particle-type binder polymer, a first fluorine particle-type binder polymer, or a combination thereof.

[0075] In one embodiment of the present invention, the first acrylic particle-type binder polymer may include, for example, an acrylic homopolymer polymerized only with an acrylic monomer, or may include a copolymer of an acrylic-derived repeating unit and a different repeating unit. For example, the first acrylic particle-type binder polymer is poly(methylmethacrylate), poly(ethylhexylacrylate), poly(butylacrylate), poly(acrylonitrile), a copolymer of ethylhexylacrylate and methylmethacrylate, a copolymer of butylacrylate and methylmethacrylate, an ethylacrylate-acrylic acid-N,N-dimethylacrylamide copolymer, an ethylacrylate-acrylic acid-2-(dimethylamino)ethylacrylate copolymer, an ethylacrylate-acrylic acid-N,N-diethylacrylamide copolymer, It may include an ethyl acrylate-acrylic acid-2-(diethylamino)ethyl acrylate copolymer or a mixture of two or more thereof.

[0076] In one embodiment of the present invention, the first fluorine-based particle-type binder polymer may include, for example, a polyvinylidene fluoride (PVDF) homopolymer, and may include a copolymer of repeating units derived from vinylidene fluoride and other repeating units. For example, the first fluorine-based particle-type binder polymer may include a copolymer of one or more selected from among repeating units derived from vinylidene fluoride, repeating units derived from trifluoroethylene (TrFE), repeating units derived from tetrafluoroethylene (TFE), repeating units derived from hexafluoropropylene (HFP), repeating units derived from trichloroethylene (TrCE), repeating units derived from trichlorofluoroethylene (TCFE), repeating units derived from chlorotrifluoroethylene (CTFE), repeating units derived from polymethylmethacrylate (PMMA), and repeating units derived from polyvinylacetate (PVAc), or a mixture of two or more thereof.

[0077] In one embodiment of the present invention, the glass transition temperature (Tg) of the first particle-shaped binder polymer may be 30°C to 80°C, or 40°C to 70°C. When the first particle-shaped binder polymer has the above-described glass transition temperature, the particle-shaped binder may collapse under certain temperature and pressure conditions at the time of manufacturing the separation membrane, thereby forming a film.

[0078] In one embodiment of the present invention, D of the first particle-type binder polymer 50The size of the first particle-type binder polymer may be 150 nm to 1 ㎛ or 200 nm to 800 nm. When the size of the first particle-type binder polymer satisfies the above-described range, the adhesion and porosity of the separator may be better.

[0079] In one embodiment of the present invention, the first particle-type binder polymer may be included in an amount ranging from 10 wt% to 90 wt% relative to 100 wt% of the inorganic coating layer. When the content of the first particle-type binder polymer satisfies the above-described range, the bonding force between the inorganic particles may be excellent, while the heat resistance of the separator may be excellent.

[0080] In one embodiment of the present invention, the first particle-type binder polymer may have a particle structure of, for example, a single-phase or a multi-phase such as core-shell, core-first shell-second shell, etc.

[0081] In one embodiment of the present invention, the first particle-shaped binder polymer may have a particle shape of, for example, a spherical, oval, plate-shaped or irregular shape.

[0082]

[0083] adhesive layer

[0084] In one embodiment of the present invention, the adhesive layer is formed on at least one surface of the inorganic coating layer and includes a second particulate binder polymer and a non-particulate binder precursor. The thickness of the adhesive layer may be in the range of 0.3 μm to 1 μm. In this case, the non-particulate binder precursor may be polymerized into a non-particulate binder polymer in a subsequent process.

[0085] In this way, when a non-particulate binder precursor is included as a binder in the adhesive layer, the molecular weight is lower than when the non-particulate binder polymer is directly included, resulting in excellent dispersibility within a dispersion medium, thereby reducing clumping and enabling uniform formation of the adhesive layer. Furthermore, this reduces the closure of pores within the adhesive layer, thereby further improving porosity and, consequently, enhancing resistance characteristics. Furthermore, since surface contact is established between the particulate binders, the swelling ratio is relatively lowered, thereby further improving the physical properties of the membrane.

[0086]

[0087] Second particle-type binder polymer

[0088] In one embodiment of the present invention, the second particulate binder polymer may have a property of maintaining its original particle shape without being deformed even when dispersed in a solvent. Specifically, the second particulate binder polymer may mean that it exists in a particle state in an aqueous solvent. Specifically, the second particulate binder polymer may mean that it has low solubility in an aqueous solvent and thus has a form that is dispersed in a particle form in the aqueous solvent. The second particulate binder polymer may have an aspect ratio in the aqueous solvent within the range of 1.0 to 1.5, 1.0 to 1.3, or 1.0 to 1.2. Here, the aspect ratio is defined as the ratio of the length of the major axis to the minor axis of the second particulate binder, and the closer it is to 1, the closer it is to a sphere. The aspect ratio can be calculated, for example, using a particle shape analyzer (QICPIC-LIXELL, Sympatec GmbH).

[0089] In one embodiment of the present invention, the second particle-type binder polymer may be a second acrylic particle-type binder polymer, a second fluorine particle-type binder polymer, or a combination thereof.

[0090] In one embodiment of the present invention, the second acrylic particle-type binder polymer may include, for example, an acrylic homopolymer polymerized only with an acrylic monomer, or may include a copolymer including an acrylic-derived repeating unit and a different monomer-derived repeating unit. For example, the second acrylic particle-type binder polymer is poly(methylmethacrylate), poly(ethylhexylacrylate), poly(butylacrylate), poly(acrylonitrile), a copolymer of ethylhexyl acrylate and methyl methacrylate, a copolymer of butylacrylate and methyl methacrylate, an ethyl acrylate-acrylic acid-N,N-dimethylacrylamide copolymer, an ethyl acrylate-acrylic acid-2-(dimethylamino)ethyl acrylate copolymer, an ethyl acrylate-acrylic acid-N,N-diethylacrylamide copolymer, It may include an ethyl acrylate-acrylic acid-2-(diethylamino)ethyl acrylate copolymer or a mixture of two or more thereof.

[0091] In one embodiment of the present invention, the second fluorine-based particle-type binder polymer may include, for example, a polyvinylidene fluoride (PVDF) homopolymer, and may include a copolymer of repeating units derived from vinylidene fluoride and other repeating units. For example, the second fluorine-based particle-type binder polymer may include a copolymer of one or more selected from among repeating units derived from vinylidene fluoride, repeating units derived from trifluoroethylene (TrFE), repeating units derived from tetrafluoroethylene (TFE), repeating units derived from hexafluoropropylene (HFP), repeating units derived from trichloroethylene (TrCE), repeating units derived from trichlorofluoroethylene (TCFE), repeating units derived from chlorotrifluoroethylene (CTFE), repeating units derived from polymethylmethacrylate (PMMA), and repeating units derived from polyvinylacetate (PVAc), or a mixture of two or more thereof.

[0092] In one embodiment of the present invention, the glass transition temperature (Tg) of the second particle-shaped binder polymer may be 30° C. to 80° C., or 40° C. to 70° C. When the second particle-shaped binder polymer has the above-described glass transition temperature, the particle-shaped binder may collapse under certain temperature and pressure conditions at the time of manufacturing the separation membrane, thereby forming a film.

[0093] In one embodiment of the present invention, D of the second particle-type binder polymer 50The size of the second particle-type binder polymer may be 150 nm to 1 μm or 200 nm to 800 nm. When the size of the second particle-type binder polymer satisfies the above-described range, the adhesion and porosity of the separator may be better.

[0094] In one embodiment of the present invention, the second particulate binder polymer may be included in a range of 10 wt% to 90 wt% relative to 100 wt% of the adhesive layer. When the content of the second particulate binder polymer satisfies the above-described range, the adhesive strength (wet adhesive strength) after impregnation with an electrolyte may be excellent, while also being advantageous in preserving the shape of the adhesive layer including the non-particulate binder polymer.

[0095] In one embodiment of the present invention, the second particle-type binder polymer may have a particle structure of, for example, a single-phase or a multi-phase such as core-shell, core-first shell-second shell, etc.

[0096] In one embodiment of the present invention, the second particle-shaped binder polymer may have a particle shape of, for example, a spherical, oval, plate-shaped or irregular shape.

[0097] In one embodiment of the present invention, the weight ratio of the first particle-type binder polymer and the second particle-type binder polymer may be 90:10 to 10:90.

[0098]

[0099] Non-particulate binder polymer

[0100] In one embodiment of the present invention, the non-particulate binder precursor comprises an acrylic monomer or oligomer. The acrylic monomer or oligomer may refer to an acrylic monomer or an acrylic oligomer.

[0101] In one embodiment of the present invention, the non-particulate binder precursor may include a thermally polymerizable acrylic monomer, a thermally polymerizable acrylic oligomer, a photopolymerizable acrylic monomer, a photopolymerizable acrylic oligomer, or two or more thereof. The thermally polymerizable acrylic monomer or thermally polymerizable acrylic oligomer may be polymerized by heat at a predetermined temperature or higher to form a thermally polymerizable acrylic polymer. The photopolymerizable acrylic monomer or photopolymerizable acrylic oligomer may be polymerized by UV to form a photopolymerizable acrylic polymer.

[0102] In one embodiment of the present invention, the acrylic monomer may be a compound having 2 to 16 carbon atoms, or 2 to 14 carbon atoms, or 2 to 12 carbon atoms. When the carbon number of the acrylic monomer satisfies the above-described range, the monomer may have better adhesive properties.

[0103] In one embodiment of the present invention, the acrylic oligomer may be a low-molecular weight polymer obtained by polymerizing two or more acrylic monomers, and may be a compound containing a reactive functional group at a molecular terminal. The acrylic oligomer may have repeating units obtained by polymerizing, for example, 2 to 20, 3 to 15, or 4 to 10 monomers.

[0104] In one embodiment of the present invention, the acrylic monomer or oligomer is butyl acrylate, β-carboxyethylacrylate, 2-ethylhexylacrylate, 2-methoxyethylacrylate, 4-hydroxybutylacrylate, ethylacrylate, 2-hydroxyethylacrylate, 2-hydroxypropyl acrylate, pentylmethacrylate, 2-hydroxymethylacrylate, ethylmethacrylate, methylmethacrylate, acrylic acid, It may be an oligomer comprising at least one monomer selected from acrylonitrile or at least one repeating unit derived therefrom. In one embodiment of the present invention, the acrylic monomer may be a mixture comprising at least one of the monomers listed above. In one embodiment of the present invention, the acrylic oligomer may be an oligomer comprising at least one repeating unit derived from the monomers listed above, and the acrylic oligomer may be a mixture comprising at least one such oligomer. Alternatively, the acrylic monomer or oligomer may be a mixture comprising both the acrylic monomer and the acrylic oligomer described above.

[0105] In one embodiment of the present invention, the non-particulate binder precursor may be polymerized at a temperature of 45°C to 85°C, 50°C to 80°C, or 55°C to 75°C to form a non-particulate binder polymer. Preferably, the non-particulate binder precursor may be polymerized at a temperature of 450°C to 85°C to form a non-particulate binder polymer. Since the temperature at which the non-particulate binder polymer is polymerized by heat may vary depending on the structure of the precursor (monomer), the temperature at which the polymerization of the non-particulate binder precursor starts can be controlled by changing the type of the non-particulate binder precursor. When the non-particulate binder precursor satisfies the above-described temperature range, the non-particulate binder precursor is polymerized at a temperature higher than room temperature, and since the non-particulate binder precursor is not polymerized in a general natural drying step, the start of polymerization can be controlled. Additionally, since the non-particulate binder precursor does not require high temperatures for polymerization, the properties of the porous polymer substrate may not deteriorate.

[0106] In one embodiment of the present invention, the non-particulate binder polymer may be a homopolymer in which one type of acrylic monomer or oligomer is polymerized, a copolymer in which two or more types of acrylic monomers or oligomers are polymerized, or a blend thereof. When the non-particulate binder polymer is a copolymer, it may be a block copolymer, a graft copolymer, a branched copolymer, an alternating copolymer, or a random copolymer. The number average molecular weight (Mn), the weight average molecular weight (Mw), and the glass transition temperature (Tg) of the non-particulate binder polymer may be controlled by controlling the type of the acrylic monomer or oligomer and the number of repeating units.

[0107] In one embodiment of the present invention, at least a portion of the second particulate binder polymer may be connected by the non-particulate binder polymer and / or the non-particulate binder precursor. As described below, during the second drying, the solvent may evaporate while the non-particulate binder precursor remains between the second particulate binder polymers, and thereafter, the non-particulate binder precursor may be polymerized into the non-particulate binder polymer. At this time, the non-particulate binder polymer may have a form that makes surface contact with the second particulate binder polymer, and may have a form that connects different second particulate binder polymers.

[0108] In one embodiment of the present invention, the thermally polymerizable acrylic monomer or oligomer may be thermally polymerized in the presence of a thermal polymerization initiator to form a non-particulate binder polymer. The thermal polymerization initiator may be introduced together with the acrylic monomer or oligomer and the molecular weight regulator included in the monomer or oligomer mixture, or may be introduced in such a manner that the monomer or oligomer mixture is first introduced into a reactor, the reaction temperature is set to the above-mentioned temperature, and then an appropriate amount is added at the time when the reaction is initiated. That is, the thermal polymerization reaction may proceed while the thermal polymerization initiator is added.

[0109] Examples of the thermal polymerization initiator include an azo initiator such as azobismetapropionate, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2-azobis-2,4-dimethylvaleronitrile, 2,2-azobisisobutyronitrile, dimethyl 2,2'-azobis(2-methylpropionate) or 2,2-azobis-2-methylbutyronitrile; Peroxyester compounds such as dipropyl peroxydicarbonate, diisopropyl peroxydicarbonate, bis-4-butylcyclohexyl peroxydicarbonate, diethoxyethyl peroxydicarbonate, diethoxyhexyl peroxydicarbonate, ethylhexyl peroxydicarbonate, hexyl peroxydicarbonate, dimethoxybutyl peroxydicarbonate, bis(3-methoxy-3-methoxybutyl)peroxydicarbonate, hexyl peroxy pivalate, amyl peroxy pivalate, butyl peroxy pivalate or trimethylhexanoyl peroxide; peroxy dicarbonate compounds such as dimethyl hydroxybutyl peroxaneodecanoate, amyl peroxy neodecanoate or butyl peroxy neodecanoate; One or more kinds of peroxide initiators such as acyl peroxides such as 3,5,5-trimethylhexanoyl peroxide, lauryl peroxide or dibenzoyl peroxide; ketone peroxides; dialkyl peroxides; peroxy ketals; or hydroperoxides may be used.

[0110]

[0111] In one embodiment of the present invention, the photopolymerizable acrylic monomer or oligomer may be a photopolymerizable acrylic monomer or oligomer that is photopolymerized in the presence of a predetermined initiator to form a non-particulate binder polymer. The initiator may be an azobis(2-methylpropionate) compound such as ethylhexyl peroxydicarbonate, dimethyl 2,2'-azobis(2-methylpropionate), or a combination thereof.

[0112]

[0113] In one embodiment of the present invention, the photopolymerizable acrylic monomer or oligomer may be photopolymerized in the presence of a photopolymerization initiator to form a non-particulate binder polymer. The photopolymerization initiator may be introduced together with the acrylic monomer and the molecular weight regulator included in the monomer mixture, or may be introduced in an appropriate amount by first introducing the monomer mixture into a reactor, irradiating it for polymerization, and then initiating the reaction. That is, the photopolymerization reaction may proceed while the photopolymerization initiator is being added.

[0114] As the above photopolymerization initiator, a benzoin-based, hydroxy ketone-based, amino ketone-based or phosphine oxide-based photopolymerization initiator may be used, and specifically, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylanino acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, Examples thereof include 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethylketal, acetophenone dimethylketal, p-dimethylamino benzoic acid ester, oligo[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone] and 2,4,6-trimethylbenzoyl-diphenyl-phosphineoxide. However, it is not limited to this.

[0115]

[0116] <Method for manufacturing a separator for lithium secondary batteries>

[0117] The present invention provides a method for manufacturing a separator for a lithium secondary battery.

[0118] According to one aspect of the present invention, a method for manufacturing a separator for a lithium secondary battery of the present invention comprises the steps of: preparing a first slurry composition including inorganic particles, a first particle-type binder polymer, and a first solvent, and a second slurry composition including a second particle-type binder polymer, a non-particulate binder precursor, and a second solvent; applying the first slurry composition onto at least one surface of a porous polymer substrate and first drying the same to form an inorganic coating layer; and applying the second slurry composition onto the inorganic coating layer and second drying the same to form an adhesive layer; and polymerizing the non-particulate binder precursor into a non-particulate binder polymer.

[0119] Below, we will examine in detail each step the manufacturing method of a separator for lithium secondary batteries.

[0120] First, a first slurry composition including inorganic particles, a first particulate binder polymer, and a first solvent and a second slurry composition including a second particulate binder polymer, a non-particulate binder precursor, and a second solvent are prepared.

[0121] Meanwhile, the inorganic particles, the first particle-type binder polymer, the second particle-type binder polymer, and the non-particle-type binder precursor are replaced with those described above.

[0122] In one embodiment of the present invention, the first solvent and the second solvent may each be an aqueous solvent or an organic solvent, and preferably an aqueous solvent.

[0123] In one embodiment of the present invention, the aqueous solvent may include water. Furthermore, when drying speed and temperature are limited, a co-solvent such as methanol, ethanol, or isopropyl alcohol, which have a lower boiling point than water, may be used.

[0124] In one embodiment of the present invention, the organic solvent is, for example, cyclic aliphatic hydrocarbons such as cyclopentane and cyclohexane; aromatic hydrocarbons such as toluene, xylene and ethylbenzene; ketones such as acetone, ethyl methyl ketone, diisopropyl ketone, cyclohexanone, methylcyclohexane and ethylcyclohexane; chlorinated aliphatic hydrocarbons such as methylene chloride, chloroform and carbon tetrachloride; esters such as ethyl acetate, butyl acetate, γ-butyrolactone and ε-caprolactone; acylonitrile such as acetonitrile and propionitrile; ethers such as tetrahydrofuran and ethylene glycol diethyl ether; alcohols such as methanol, ethanol, isopropanol, ethylene glycol and ethylene glycol monomethyl ether; amides such as N-methylpyrrolidone and N,N-dimethylformamide. It can be included, and the solvent may include acetone in consideration of the advantage in the drying process.

[0125] In one embodiment of the present invention, the weight ratio of the inorganic particles and the first particle-type binder polymer in the first slurry composition may be 1:99 to 99:1, 10:90 to 90:10, or 20:80 to 80:20. When the weight ratio of the inorganic particles and the first particle-type binder polymer satisfies the above-described range, the heat resistance of the separator may be excellent, and the bonding between the inorganic particles may be excellent.

[0126] In one embodiment of the present invention, the weight ratio of the second particulate binder polymer and the non-particulate binder precursor in the second slurry composition may be 1:99 to 99:1, 10:90 to 90:10, or 20:80 to 80:20. When the weight ratio of the second particulate binder polymer and the non-particulate binder precursor satisfies the above-described range, the electrode adhesion in the electrolyte-impregnated state of the separator (wet adhesion) and the electrode adhesion in the dry state of the separator (dry adhesion) may be better.

[0127]

[0128] Thereafter, the step of applying the first slurry composition onto at least one surface of the porous polymer substrate and drying it for the first time to form an inorganic coating layer; and the step of applying the second slurry composition onto the inorganic coating layer and drying it for the second time to form an adhesive layer. In this case, the content of the binder polymer of the adhesive layer can be controlled, and the resistance characteristics can be excellent.

[0129] In another embodiment of the present invention, the first slurry composition may be applied to at least one surface of a porous polymer substrate, the second slurry composition may be additionally applied onto the applied first slurry composition, and then dried to simultaneously form an inorganic coating layer and an adhesive layer. This has the advantages of reducing manufacturing costs and time and simplifying the process.

[0130]

[0131] In one embodiment of the present invention, the method for applying the first slurry composition and the second slurry composition may use any conventional coating method known in the art without limitation, and for example, various methods such as dip coating, die coating, roll coating, comma coating, microgravure coating, doctor blade coating, reverse roll coating, Mayer Bar coating, direct metering coating, or a mixture thereof may be used.

[0132]

[0133] In one embodiment of the present invention, the time, speed and temperature of the first drying and the second drying may be different depending on the solvent used.

[0134] In one embodiment of the present invention, the first drying time and the second drying time may be performed for 30 seconds to 10 hours, respectively, and the first drying temperature and the second drying temperature may be performed in a range of 30°C to 100°C, or 30°C to 60°C, respectively. The drying is not limited to a specific method as long as the washing solution can be removed from the separator, and for example, an appropriate method such as one or a combination of two or more of convection drying, hot air drying, blowing drying, and natural drying may be applied.

[0135]

[0136] In one embodiment of the present invention, the drying temperature of the first drying step may be performed at a lower temperature than the temperature of the second drying step. For example, the drying temperature in the first drying step may be performed at a temperature of 30°C to 35°C, and the drying temperature in the second drying step may be performed at a temperature of 35°C to 40°C. When the temperatures of the first and second drying steps satisfy the above-described ranges, the physical properties of the porous polymer substrate may not be deteriorated.

[0137]

[0138] Thereafter, a step of polymerizing the non-particulate binder precursor into a non-particulate binder polymer is included.

[0139] In one embodiment of the present invention, the polymerizing step may be performed at a temperature of 45°C to 85°C, 50°C to 80°C, or 55°C to 75°C. Since the temperature at which the non-particulate binder polymer is polymerized by heat may vary depending on the structure of the non-particulate binder precursor, the temperature at which the polymerization of the non-particulate binder precursor starts can be controlled by changing the type of the non-particulate binder precursor. When the polymerization initiation temperature of the non-particulate binder precursor satisfies the above-described temperature range, the non-particulate binder precursor is polymerized at a temperature higher than room temperature, so that the non-particulate binder precursor is not polymerized in a general natural drying step, thereby controlling the start of polymerization. In addition, since the non-particulate binder precursor does not require a high temperature to be polymerized, the physical properties of the porous polymer substrate may not be deteriorated.

[0140] In one embodiment of the present invention, the second drying step may be performed at a temperature lower than the temperature at which the non-particulate binder precursor polymerizes. In this case, the temperature at which the polymerization of the non-particulate binder precursor begins can be controlled.

[0141]

[0142] Lithium secondary battery

[0143] The present invention provides a lithium secondary battery.

[0144] According to one aspect of the present invention, a lithium secondary battery of the present invention comprises: a positive electrode; an negative electrode; an electrolyte; and a separator interposed between the positive electrode and the negative electrode; wherein the separator comprises: a porous polymer substrate; at least one inorganic coating layer formed on at least one surface of the porous polymer substrate and including inorganic particles and a first particulate binder polymer; and at least one adhesive layer formed on at least one surface of the inorganic coating layer and including a second particulate binder polymer and a non-particulate binder polymer; wherein the non-particulate binder polymer is characterized in that it is formed by polymerizing a non-particulate binder precursor including an acrylic monomer or oligomer.

[0145] In one embodiment of the present invention, the acrylic monomer or oligomer may mean the acrylic monomer or the acrylic oligomer.

[0146] In one embodiment of the present invention, the positive electrode can be manufactured by coating a composition for forming a positive electrode including a positive electrode active material, a binder, a conductive agent, a solvent, etc. on a positive electrode current collector.

[0147] The above-mentioned cathode active material may be a conventional cathode active material that can be used in the cathode of a conventional electrochemical device. For example, the above-mentioned cathode active material may be lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron oxide, or a lithium composite oxide comprising these.

[0148] At this time, the positive electrode active material may be included in an amount of 80 to 99 wt%, preferably 85 to 98 wt%, based on the total solid content of the composition for forming the positive electrode. When the content of the positive electrode active material satisfies the above-described range, excellent capacity characteristics can be exhibited.

[0149] 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, the positive electrode current collector may be made of stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc.

[0150] The above binder is a component that assists in the bonding of the active material and the conductive material and the bonding to the current collector, and can typically be added in an amount of 1 to 30 wt% based on the total solid weight of the composition for forming the positive electrode. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluororubber, various copolymers, etc.

[0151] The above-mentioned conductive agent can typically be added in an amount of 1 wt% to 30 wt% based on the total solid weight of the composition for forming the anode.

[0152] The conductive material is not particularly limited as long as it is conductive and does not cause a chemical change in the battery, and examples thereof include: graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers or metal fibers; metal powders such as fluorinated carbon, aluminum, and nickel powders; conductive whiskeys such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives. Specific examples of commercially available conductive agents include acetylene black series (Chevron Chemical Company, Denka Singapore Private Limited, Gulf Oil Company), Ketjenblack, EC series (Armak Company), Vulcan XC-72 (Cabot Company), and Super P (Timcal).

[0153] In addition, the positive electrode active material layer may optionally further include a dispersant as needed.

[0154] The above dispersant can be used without any special restrictions as long as it is used as a dispersant of the anode, and for example, an aqueous dispersant or an organic dispersant can be selectively used as needed. Preferably, the dispersant is a cellulose compound, polyalkylene oxide, polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl acetal, polyvinyl ether, polyvinyl sulfonic acid, polyvinyl chloride (PVC), polyvinylidene fluoride, chitosan, starch, amylose, polyacrylamide, poly-N-isopropylacrylamide, poly-N,N-dimethylacrylamide, polyethyleneimine, polyoxyethylene, poly(2-methoxyethoxyethylene), poly(acrylamide-co-diallyldimethylammonium chloride), acrylonitrile / butadiene / styrene (ABS) polymer, acrylonitrile / styrene / acrylate ester (ASA) polymer, a mixture of acrylonitrile / styrene / acrylate ester (ASA) polymer and propylene carbonate, styrene / acrylonitrile (SAN) Examples thereof include copolymers, methyl methacrylate / acrylonitrile / butadiene / styrene (MABS) polymers, styrene butadiene rubber, nitrile butadiene rubber, and fluoroelastomers, and any one or a mixture of two or more thereof may be used. Hydrogenated nitrile butadiene rubber (H-NBR) may be used. When the positive electrode active material layer further includes a dispersant, the dispersibility of the components of the positive electrode active material layer, particularly the conductive material, may be increased, but is not limited thereto.

[0155] In addition, the solvent may be a solvent generally used in the relevant technical field, such as dimethylsulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water, and one of these may be used alone or as a mixture of two or more. The amount of the solvent used is sufficient to dissolve or disperse the positive electrode active material, conductive material, and binder in consideration of the coating thickness and manufacturing yield of the slurry, and to have a viscosity that can exhibit excellent thickness uniformity when applied thereafter for manufacturing the positive electrode.

[0156]

[0157] The negative electrode according to the present invention can be manufactured by coating a negative electrode forming composition including the above-described negative electrode active material, binder, conductive agent, solvent, etc. on a negative electrode current collector. In addition, the negative electrode forming composition may optionally further include a dispersant as needed.

[0158] As the negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium may be used. Preferably, the negative electrode is a silicon-based negative electrode active material, a carbon-based negative electrode active material, or Li that exhibits high-capacity characteristics. x Fe2O3(0≤x≤1), Li x WO2(0≤x≤1), Sn x Me 1-x Me' y O z(Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, elements of group 1, 2, and 3 of the periodic table, halogens; 0 <x≤1; 1≤y≤3; 1≤z≤8) 등의 금속 복합 산화물; 리튬 금속; 리튬 합금; 주석계 합금; SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, 및 Bi2O5등의 금속 산화물; 폴리아세틸렌 등의 도전성 고분자; Li-Co-Ni 계 재료; 티타늄 산화물; 리튬 티타늄 산화물 등의 음극 활물질을 더 사용할 수 있다. 상기 규소계 음극 활물질은 Si, SiOx(0.1<x<5), Si-금속 합금, Mg와 같은 금속이 도핑 또는 화학 결합된 실리콘 산화물 입자(SiOx, 0.1<x<5) 및 Si와 SiOx(0.1<x<5)의 합금으로 이루어진 군에서 선택된 하나 이상을 포함할 수 있다. 상기 탄소계 음극 활물질은 천연 흑연, 인조 흑연, 비정질 하드카본(hard carbon), 저결정질 소프트카본(soft carbon), 카본 블랙, 아세틸렌 블랙, 케첸 블랙, 수퍼 P, 그래핀 (graphene), 및 섬유상 탄소로 이루어진 군으로부터 선택되는 하나 이상을 포함할 수 있다.

[0159] The negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used. In addition, the negative electrode current collector can typically have a thickness of 3 ㎛ to 500 ㎛, and like the positive electrode current collector, fine unevenness can be formed on the surface of the current collector to strengthen the bonding strength of the negative electrode active material. For example, it can be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc.

[0160] The conductive material, binder, solvent or dispersant included in the above-described composition for forming the cathode may be applied without any special limitation as long as it is generally usable in a composition for forming an electrode. For example, the conductive material, binder, solvent or dispersant described in the above-described composition for forming the anode may be applied.

[0161]

[0162] In addition, the lithium secondary battery may further include an electrolyte. The electrolyte may include, but is not limited to, an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel-type polymer electrolyte, a solid inorganic electrolyte, a molten inorganic electrolyte, etc. that can be used in the manufacture of a lithium secondary battery.

[0163] Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0164] The organic solvent may be used without any particular limitation as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the organic solvent may include ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; Carbonate solvents such as dimethylcarbonate (DMC), diethylcarbonate (DEC), methylethylcarbonate (MEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R represents a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double-bonded aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes can be used. Among these, a carbonate solvent is preferable, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate, etc.) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of the battery and a linear carbonate compound having low viscosity (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate, etc.) is more preferable.In this case, the performance of the electrolyte may be improved when the cyclic carbonate and the chain carbonate are mixed and used in a volume ratio of about 1:1 to about 1:9.

[0165] The lithium salt may be used without any particular limitation as long as it is a compound capable of providing lithium ions used in a lithium secondary battery. Specifically, the lithium salt may be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2. LiCl, LiI, or LiB(C2O4)2. It is preferable that the concentration of the lithium salt be used within the range of 0.1 to 2.0 M. When the concentration of the lithium salt is within the above range, the electrolyte can exhibit excellent electrolyte performance because it has appropriate conductivity and viscosity, and lithium ions can move effectively.

[0166] In addition to the electrolyte components, the electrolyte may further contain one or more additives, such as haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ethers, ethylene diamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, or aluminum trichloride, for the purpose of improving the life characteristics of the battery, suppressing battery capacity decrease, and improving the discharge capacity of the battery. At this time, the additives may be contained in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the total weight of the electrolyte.

[0167]

[0168] In one embodiment of the present invention, the separator may have an electrode adhesion (wet adhesion) of 7 gf / 20 mm or more, 8 gf / 20 mm or more, 9 gf / 20 mm or more, or 10 gf / 20 mm or more after electrolyte injection. When the electrode adhesion satisfies the above-described properties, the electrode adhesion is excellent, and bending of the separator or the like may not occur.

[0169] The above electrode adhesion (wet adhesion) may refer to the adhesion between the positive electrode and the electrode after the separator is immersed in the electrolyte. The electrode adhesion may be measured by cutting the positive electrode and the separator, each of which has a positive electrode active material layer formed on an aluminum current collector, into a width of 20 mm, placing them in a pouch, pouring electrolyte, and then pressurizing the pouch under the conditions of 5 kgf, 70°C, and 4 minutes to prepare a sample for measuring electrode adhesion. A universal testing machine (e.g., Instron's UTM equipment) may be used to perform a 90° peel test under the conditions of 200 mm / min. At this time, the electrolyte may be the electrolyte described above.

[0170]

[0171] In one embodiment of the present invention, the solubility of the non-particulate binder polymer may be 20% or less, 15% or less, 12% or less, or 10% or less. In addition, the solubility of the non-particulate binder polymer may be 0% or more, 1% or more, or 2% or more. When the solubility of the non-particulate binder polymer satisfies the above-described range, the dissolution stability of the non-particulate binder polymer in the electrolyte can be secured, and the adhesive strength can be maintained even after the electrolyte is injected.

[0172] At this time, the solubility of the non-particulate binder polymer can be calculated by the following Equation 1. Specifically, the solubility of the non-particulate binder polymer or the non-particulate binder precursor is determined by drying the non-particulate binder polymer or the non-particulate binder precursor to prepare a sample of a predetermined weight, for example, 1 g, placing the sample in a net, dissolving it in an electrolyte, and then immersing it in a separately prepared identical electrolyte after 24 hours to perform a rinsing process, drying it, and measuring the weight of the remaining amount compared to the initial weight. At this time, the electrolyte used may be the aforementioned electrolyte, but for example, 1 M LiPF6 dissolved in a solvent in which ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are mixed in a volume ratio of 3:7 may be used.

[0173] [Formula 1]

[0174] Solubility (%) = {(Weight measured before immersion - Weight measured after immersion) / (Weight measured before immersion)} x 100

[0175]

[0176] In one embodiment of the present invention, the swelling ratio of the non-particulate binder polymer may be in the range of 50% to 500%, 55% to 400%, or 60% to 300%. When the swelling ratio of the non-particulate binder polymer satisfies the above-described range, the wet adhesion may be excellent, and the porosity and resistance characteristics of the separator in the battery may be excellent.

[0177] At this time, the swelling ratio of the non-particulate binder polymer can be calculated by the following Equation 2. Specifically, the swelling ratio of the non-particulate binder polymer or the non-particulate binder precursor can be measured by measuring the weight of the non-particulate binder polymer or the non-particulate binder precursor, dissolving the non-particulate binder polymer / non-particulate binder precursor in an electrolyte for 24 hours, and then obtaining the immersed non-particulate binder polymer / non-particulate binder precursor from the electrolyte and comparing it with the initial weight. At this time, the electrolyte used can be replaced with the above-mentioned one, but for example, 1M LiPF6 dissolved in a solvent in which ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are mixed in a volume ratio of 3:7 can be used.

[0178] [Formula 2]

[0179] Swelling ratio (%) = {(Weight measured after immersion - Weight measured before immersion) / (Weight measured before immersion)} x 100

[0180]

[0181] In one embodiment of the present invention, the air permeability of the separator may be in a range of 40 sec / 100cc to 80 sec / 100cc, 50 sec / 100cc to 78 sec / 100cc, or 60 sec / 100cc to 76 sec / 100cc. When the air permeability of the separator satisfies the above-described range, the resistance characteristics of the separator may be excellent, and the initial discharge capacity and output characteristics of the manufactured lithium secondary battery may be improved.

[0182] At this time, the air permeability of the separator can be measured using a Gurley-type air permeability meter, for example, according to JIS P-8117, and specifically, can be derived by measuring the time it takes for 100 ml of air to pass through a separator having a diameter of 28.6 mm and an area of ​​645 ㎟. In addition, the air permeability of the separator can be measured before being heat-pressed in the electrode assembly, that is, when it exists as a non-particulate binder precursor, or after being heat-pressed, when it exists as a binder polymer.

[0183]

[0184] <Method for manufacturing lithium secondary batteries>

[0185] The present invention provides a method for manufacturing a lithium secondary battery.

[0186] According to one aspect of the present invention, a method for manufacturing a lithium secondary battery of the present invention comprises: a first electrode; a second electrode; an electrolyte; and a separator interposed between the first electrode and the second electrode; a method for manufacturing a lithium secondary battery, the method comprising: a step of sequentially laminating the first electrode, the separator, and the second electrode to manufacture a laminate; a step of laminating the laminate at a temperature of 45° C. to 85° C. for 1 to 120 seconds to manufacture an electrode assembly; and a step of injecting an electrolyte into the electrode assembly, wherein the separator comprises: a porous polymer substrate; at least one inorganic coating layer formed on at least one surface of the porous polymer substrate, the inorganic particles, and a first particle-type binder polymer; And at least one adhesive layer formed on at least one surface of the inorganic coating layer, and including a second particle-type binder polymer and a non-particulate binder polymer; wherein the non-particulate binder polymer is formed by polymerizing a non-particulate binder precursor including an acrylic monomer or oligomer.

[0187]

[0188] In one embodiment of the present invention, the first electrode and the second electrode have different polarities, for example, the first electrode and the second electrode may be an anode and a cathode, or a cathode and an anode, respectively. Meanwhile, the anode, the cathode, and the electrolyte are replaced as described above.

[0189]

[0190] Below, we will examine the manufacturing method of lithium secondary batteries in detail, step by step.

[0191] First, a laminate is manufactured by sequentially laminating a first electrode, a separator, and a second electrode.

[0192] Thereafter, the laminate is laminated at a temperature of 45°C to 85°C, 50°C to 80°C for 1 to 120 seconds, 20 to 100 seconds, or 40 to 80 seconds to manufacture an electrode assembly.

[0193] In one embodiment of the present invention, the lamination may be performed under pressure conditions of 0.5 MPa to 20 MPa, 1 MPa to 10 MPa, or 2 MPa to 8 MPa.

[0194]

[0195] At this time, the separation membrane comprises: a porous polymer substrate; at least one inorganic coating layer formed on at least one surface of the porous polymer substrate and including inorganic particles and a first particle-type binder polymer; and at least one adhesive layer formed on at least one surface of the inorganic coating layer and including a second particle-type binder polymer and a non-particulate binder polymer; wherein the non-particulate binder polymer is formed by polymerizing a non-particulate binder precursor including an acrylic monomer or oligomer.

[0196]

[0197] In one embodiment of the present invention, the separator may be formed by forming an inorganic coating layer and an adhesive layer on one surface of a porous polymer substrate as described above and then drying the same. At this time, a first drying of drying a first slurry composition forming an inorganic coating layer as described above and a second drying of drying a second slurry composition forming an adhesive layer may be performed.

[0198] In one embodiment of the present invention, when the temperature of the second drying is performed at a temperature lower than the temperature at which the non-particulate binder precursor is polymerized, the non-particulate binder precursor included in the adhesive layer of the separator is not polymerized, and when the lamination is performed at a temperature higher than the temperature at which the non-particulate binder precursor is polymerized, the non-particulate binder precursor is polymerized during the lamination to form a non-particulate binder polymer.

[0199]

[0200] Hereinafter, the present invention will be described in more detail through examples, but the following examples are intended to illustrate the present invention, and the scope of the present invention is not limited to these examples.

[0201] <Example 1>

[0202] Aluminum oxide (Al2O3, D) as inorganic particles 50 : 450 nm, Sumitomo Corporation), and an acrylic particle-type binder polymer (polyacrylate, Tg: 40℃ D) as the first particle-type binder polymer. 50 : 400 nm) was added to water at room temperature and stirred uniformly to prepare a first slurry composition. At this time, the solid content of the first slurry composition was 35 wt%, and the weight ratio of the inorganic particles: the first particle-type binder polymer was 80:20.

[0203] As a second particle-type binder polymer, a fluorine-based particle-type binder (PVDF, Tg: 40℃ D) 50: 400 nm), butylacrylate as a non-particulate binder precursor, and azobis(2-methylpropionate) series compound as a thermal polymerization initiator were added to water at room temperature and stirred uniformly to prepare a second slurry composition. At this time, the solid content of the second slurry composition was 10 wt%, and the weight ratio of the second particulate binder polymer:non-particulate binder precursor was 60:40.

[0204] The first slurry composition was applied to both sides of a polypropylene substrate (ventilation: 59 sec / 100cc) with a thickness of 9 μm using a doctor blade, and then dried at a temperature of 40°C for 120 seconds to form an inorganic coating layer with a thickness of 1.5 μm on each side.

[0205] Thereafter, a second slurry composition was applied to both surfaces of the separator having the inorganic coating layer formed thereon using a doctor blade, and then dried at a temperature of 40°C for 60 seconds to form an adhesive layer having a thickness of 0.5 μm on each surface, thereby manufacturing a separator without polymerizing the non-particulate binder precursor. Thereafter, the separator was laminated between the positive and negative electrodes, and heated and pressed at a temperature of 70°C for 30 seconds to polymerize the acrylic monomer as the non-particulate binder precursor into a non-particulate binder polymer.

[0206]

[0207] At this time, the positive and negative electrodes were manufactured as follows:

[0208] A slurry of positive electrode active material was prepared by adding LiCoO2 as a positive electrode active material, carbon black as a conductive material, and polyvinylidene fluoride (PVdF) as a binder to N-methylpyrrolidone (NMP) as a solvent at a weight ratio of 96:2:2. The positive electrode active material slurry was coated on a sheet-shaped aluminum current collector and dried to obtain a final positive electrode loading of 3.8 mAh / cm. 2 The polarity was prepared to make this happen.

[0209] Artificial graphite as a negative active material, carbon black as a conductive agent, carboxymethyl cellulose as a dispersant, and styrene butadiene emulsion as a binder were mixed in a weight ratio of 96:0.5:1.5:2.0, respectively, and added to water as a solvent to prepare a negative electrode slurry. The negative electrode slurry was prepared at a capacity of 4.0 mAh / cm 2 A negative electrode having a negative active material layer formed by coating and drying a copper current collector with a loading amount of was prepared.

[0210]

[0211] <Example 2>

[0212] In Example 1, the process was the same as in Example 1 except that β-carboxyethylacrylate was used instead of butyl acrylate as a non-particulate binder precursor.

[0213]

[0214] <Example 3>

[0215] In Example 1, a non-particulate binder precursor was prepared in the same manner as in Example 1, except that butylacrylate and β-carboxyethyl acrylate were used in a weight ratio of 1:1 instead of butylacrylate.

[0216]

[0217] <Comparative Example 1>

[0218] In Example 1, it was manufactured in the same manner as in Example 1, except that the adhesive layer was not formed.

[0219]

[0220] <Comparative Example 2>

[0221] In Example 1, the adhesive layer was manufactured in the same manner as in Example 1, except that the non-particulate binder precursor (acrylic diaphragm) and thermal polymerization initiator were not included.

[0222]

[0223] <Comparative Example 3>

[0224] In Example 1, the adhesive layer was manufactured in the same manner as in Example 1, except that a thermal polymerization initiator was not included.

[0225]

[0226] Comparative Example 4

[0227] In Example 1, a separator without polymerization of a non-particulate binder precursor (acrylic monomer) was laminated between the positive and negative electrodes, and the membrane was manufactured in the same manner as in Example 1, except that the membrane was pressed for 30 seconds at a temperature (40°C) lower than the polymerization initiation temperature.

[0228]

[0229] Comparative Example 5

[0230] In Example 1, a separator including a non-particulate binder polymer instead of a non-particulate binder precursor was used between the positive and negative electrodes, and the same procedure as in Example 1 was followed.

[0231] Aluminum oxide (Al2O3, D) as inorganic particles 50 : 450 nm, Sumitomo Corporation), and an acrylic particle-type binder polymer (polyacrylate, Tg: 40℃ D) as the first particle-type binder polymer. 50 : 400 nm) was added to water at room temperature and stirred uniformly to prepare a first slurry composition. At this time, the solid content of the first slurry composition was 35 wt%, and the weight ratio of the inorganic particles: the first particle-type binder polymer was 80:20.

[0232] As a second particle-type binder polymer, a fluorine-based particle-type binder (PVDF, Tg: 40℃ D) 50 : 400 nm), polyacrylate as a non-particulate binder polymer was added to water and stirred uniformly to prepare a second slurry composition.

[0233] At this time, the solid content of the second slurry composition was 10 wt%, and the weight ratio of the second particle-type binder polymer:non-particle-type binder polymer was 60:40.

[0234] The first slurry composition was applied to both sides of a polypropylene substrate (ventilation: 59 sec / 100cc) with a thickness of 9 μm using a doctor blade, and then dried at a temperature of 40°C for 120 seconds to form an inorganic coating layer with a thickness of 1.5 μm on each side.

[0235] Afterwards, the second slurry composition was applied to both sides of the separator on which the inorganic coating layer was formed using a doctor blade, and then dried at a temperature of 40°C for 60 seconds to form an adhesive layer with a thickness of 0.5 μm on each side.

[0236] At this time, the positive and negative electrodes were manufactured in the same manner as in Example 1.

[0237]

[0238] <Experimental Example>

[0239] For each example and each comparative example, solubility, swelling ratio, thickness, air permeability, wet adhesion (anode-separator adhesion after electrolyte impregnation), and resistance were measured and presented in Table 1 below.

[0240] Solubility (%)Swelling ratio (%)Thickness (㎛)Adhesive layerBinder loading amount (g / m) 2 )Air permeability (sec / 100cc)Wet adhesion (gf / 20mm)Resistance (ohm)Example 1613513.00.776140.67Example 236413.10.76870.61Example 359013.00.671110.62Comparative example 10011.805600.49Comparative example 243013.00.66630.58Comparative example 33356013.10.76940.64Comparative example 43151013.00.67370.63Comparative example 56016012.91.585100.60

[0241] The separators of Examples 1 to 3 had low solubility of the non-particulate binder polymer contained in the separators in the electrolyte, and the electrolyte swelling ratio was not large. Meanwhile, the separators of Examples 1 to 3 had excellent air permeability and resistance, and the wet adhesive strength was generally superior to that of Comparative Examples 1 to 4.

[0242] Meanwhile, Comparative Example 1 had inferior wet adhesion because no adhesive layer was formed. Comparative Example 2 had inferior wet adhesion because the adhesive layer contained only the second particle-type binder polymer. Comparative Example 3 had inferior solubility and swelling characteristics because the non-particulate binder precursor was not thermally polymerized, and the wet adhesion of the separator was also inferior. Comparative Example 4 had inferior solubility and swelling characteristics because the non-particulate binder precursor was not thermally polymerized, and the wet adhesion was also inferior.

[0243] Comparative Example 5 showed that the non-particulate binder polymer in the adhesive layer of the separator was not polymerized in a precursor state, but was included during the manufacturing stage of the separator. Accordingly, the solubility and swelling ratio of the non-particulate binder polymer were inferior, and in particular, it was confirmed that the non-particulate binder polymer was excessively dissolved. In addition, the air permeability characteristics of the separator were inferior, and it was confirmed that the binder loading amount in the adhesive layer had to be formed twice that of the examples to have a similar adhesive strength to the examples.

[0244]

[0245] <Measurement method>

[0246] Solubility

[0247] The non-particulate binder polymer / non-particulate binder precursor used in each example and comparative example was dried to prepare a 1 g sample. The sample was placed in a mesh bag and dissolved in an electrolyte, and after 24 hours, it was immersed in a separately prepared identical electrolyte to perform a rinsing process. Afterwards, it was dried, and the weight of the remaining amount was compared with the initial weight. The solubility was calculated based on the following equation 1 and is shown in Table 1. At this time, the electrolyte used was a 1 M LiPF6 dissolved in a solvent containing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 3:7.

[0248] [Formula 1]

[0249] Solubility (%) = {(Weight measured before immersion - Weight measured after immersion) / (Weight measured before immersion)} x 100

[0250]

[0251] Swelling ratio

[0252] The weight of the non-particulate binder polymer / non-particulate binder precursor used in each example and comparative example was measured, and the non-particulate binder polymer / non-particulate binder precursor was dissolved in the electrolyte for 24 hours, and then the immersed non-particulate binder polymer / non-particulate binder precursor was obtained from the electrolyte and compared with the initial weight. The swelling ratio was calculated based on the following equation 2 and is shown in Table 1. At this time, the electrolyte used was a solvent in which ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed in a volume ratio of 3:7 and 1 M LiPF6 was dissolved.

[0253] [Formula 2]

[0254] Swelling ratio (%) = {(Weight measured after immersion - Weight measured before immersion) / (Weight measured before immersion)} x 100

[0255]

[0256] thickness

[0257] The thickness of the membranes manufactured in each example and comparative example was measured using a thickness measuring device (Mitutoyo, VL-50S-B) and is shown in Table 1.

[0258]

[0259] ventilation

[0260] The pre-heat-pressed separation membranes manufactured in each example and comparative example were measured using a Gurley-type air permeability meter according to JIS P-8117. At this time, the time for 100 ml of air to pass through a 28.6 mm diameter and 645 mm2 area was measured.

[0261]

[0262] Wet adhesion (anode-separator adhesion after electrolyte impregnation)

[0263] The positive electrode having a positive electrode active material layer formed on an aluminum current collector and the separator manufactured in each example and comparative example were cut to a width of 20 mm and placed in a pouch, and a carbonate-based electrolyte was injected.

[0264] The above pouch was pressurized under the conditions of 5 kgf, 70°C, and 4 minutes to prepare a sample for measuring electrode adhesion.

[0265] In order to measure the adhesion between the above-mentioned anode and separator, a 90° peel test was conducted at 200 mm / min using Instron's UTM equipment.

[0266]

[0267] resistance

[0268] Coin cells were manufactured by sandwiching the separators manufactured in each example and comparative example between SUS.

[0269] An electrolyte containing 1M LiPF6 and a mixture of ethylene carbonate and ethyl methyl carbonate in a volume ratio of 1:2 was injected into the coin cell.

[0270] In order to measure the resistance of the above coin cells, the resistance was measured through electrochemical impedance spectroscopy analysis using VMP3 from BioLogic Science Instrument at 25°C under conditions of amplitude 10 mV and scan range 0.1 Hz to 1 MHz, and the results are shown in Table 1 below.

[0271]

[0272] Entry diameter (Dn)

[0273] The above particle diameter (Dn) was measured using the laser diffraction method. Specifically, the powder to be measured was dispersed in water at a content of 0.1 wt% or less, and then introduced into Microtrac S3500. The particle size distribution was calculated by measuring the difference in diffraction patterns according to particle size when the particles passed through the laser beam. By calculating the particle diameter at points where it was 10%, 50%, and 90% of the cumulative distribution of the number of particles according to particle diameter in the measuring device, D 10 , D 50 and D 90 can be measured.

[0274]

[0275] Glass transition temperature (Tg)

[0276] The glass transition temperature of the binder polymer was measured by drying the binder polymer and forming a film, and then measuring the glass transition temperature (Tg) using DSC (DSC 2920, TA Instrument).

Claims

1. Porous polymer substrate; At least one inorganic coating layer formed on at least one surface of the porous polymer substrate, the inorganic coating layer including inorganic particles and a first particle-type binder polymer; and At least one adhesive layer formed on at least one surface of the inorganic coating layer and including a second particle-type binder polymer and a non-particulate binder precursor; A separator for a lithium secondary battery, characterized in that the non-particulate binder precursor comprises an acrylic monomer or oligomer.

2. In claim 1, A separator for a lithium secondary battery, characterized in that the non-particulate binder precursor comprises a thermally polymerizable acrylic monomer, a thermally polymerizable acrylic oligomer, a photopolymerizable acrylic monomer, a photopolymerizable acrylic oligomer, or two or more thereof.

3. In claim 1, A separator for a lithium secondary battery, characterized in that the non-particulate binder precursor is polymerized under conditions of a temperature of 45°C to 85°C to form a non-particulate binder polymer.

4. In claim 1, The above acrylic monomer or oligomer is selected from the group consisting of butyl acrylate, β-carboxyethylacrylate, 2-ethylhexylacrylate, 2-methoxyethylacrylate, 4-hydroxybutylacrylate, ethylacrylate, 2-hydroxyethylacrylate, 2-hydroxypropyl acrylate, pentylmethacrylate, 2-hydroxymethylacrylate, ethylmethacrylate, methylmethacrylate, acrylic acid, and acrylonitrile. A separator for a lithium secondary battery, characterized in that it is an oligomer comprising one or more selected monomers or one or more repeating units derived therefrom.

5. In claim 1, A separator for a lithium secondary battery, characterized in that the weight ratio of the second particle-type binder polymer and the non-particulate binder precursor is 90:10 to 10:

90.

6. In claim 1, A separator for a lithium secondary battery, characterized in that at least a portion of the second particle-type binder polymer is connected by the non-particulate binder precursor.

7. In claim 1, A separator for a lithium secondary battery, characterized in that the weight ratio of the first particle-type binder polymer and the second particle-type binder polymer is 90:10 to 10:

90.

8. A step of preparing a first slurry composition comprising inorganic particles, a first particulate binder polymer, and a first solvent, and a second slurry composition comprising a second particulate binder polymer, a non-particulate binder precursor, and a second solvent; A step of applying the first slurry composition on at least one surface of a porous polymer substrate and drying it to form an inorganic coating layer; and A step of applying the second slurry composition onto the inorganic coating layer and drying it for the second time to form an adhesive layer; and A method for manufacturing a separator for a lithium secondary battery, characterized in that it comprises a step of polymerizing the non-particulate binder precursor into a non-particulate binder polymer.

9. In claim 8, A method for manufacturing a separator for a lithium secondary battery, characterized in that the polymerizing step is performed at a temperature of 45°C to 85°C.

10. In claim 8, A method for manufacturing a separator for a lithium secondary battery, characterized in that the step of forming an adhesive layer by drying the second layer is performed at a temperature lower than the temperature at which the non-particulate binder precursor is polymerized into a non-particulate binder polymer.

11. It includes a positive electrode; a negative electrode; an electrolyte; and a separator interposed between the positive electrode and the negative electrode; The above separator Porous polymer substrate; At least one inorganic coating layer formed on at least one surface of the porous polymer substrate, the inorganic coating layer including inorganic particles and a first particle-type binder polymer; and At least one adhesive layer formed on at least one surface of the inorganic coating layer and including a second particle-type binder polymer and a non-particulate binder polymer; A lithium secondary battery characterized in that the above non-particulate binder polymer is formed by polymerizing a non-particulate binder precursor containing an acrylic monomer or oligomer.

12. In claim 11, A lithium secondary battery, characterized in that the above separator has an electrode adhesion (wet adhesion) of 7 gf / 20 mm or more after electrolyte injection.

13. In claim 11, A lithium secondary battery characterized in that the solubility of the non-particulate binder polymer calculated by the following equation 1 is 20% or less: [Formula 1] Solubility (%) = {(Weight measured before immersion - Weight measured after immersion) / (Weight measured before immersion)} x 100 14. In claim 11, A lithium secondary battery characterized in that the swelling ratio of the non-particulate binder polymer calculated by the following Equation 2 is in the range of 50% to 500%: [Formula 2] Swelling ratio (%) = {(Weight measured after immersion - Weight measured before immersion) / (Weight measured before immersion)} x 100 15. In claim 11, A lithium secondary battery, characterized in that the air permeability of the above separator is in the range of 40 sec / 100cc to 80 sec / 100cc.

16. A method for manufacturing a lithium secondary battery comprising: a first electrode; a second electrode; an electrolyte; and a separator interposed between the first electrode and the second electrode; A step of manufacturing a laminate by sequentially laminating the first electrode, separator, and second electrode; A step of manufacturing an electrode assembly by laminating the above laminate at a temperature of 45°C to 85°C for 1 to 120 seconds; and A step of injecting an electrolyte into the above electrode assembly is included, The above separator is a porous polymer substrate; At least one inorganic coating layer formed on at least one surface of the porous polymer substrate, the inorganic coating layer including inorganic particles and a first particle-type binder polymer; and At least one adhesive layer formed on at least one surface of the inorganic coating layer and including a second particle-type binder polymer and a non-particulate binder polymer; A method for manufacturing a lithium secondary battery, wherein the non-particulate binder polymer is formed by polymerizing a non-particulate binder precursor containing an acrylic monomer or oligomer.

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