Separator for electrochemical device, method for manufacturing same, and electrochemical device comprising same

Abstract

The present invention relates to a separator for an electrochemical device, an electrochemical device comprising same, and a method for manufacturing same, the separator for an electrochemical device having, on a coating layer, an adhesive layer comprising a small amount of a water-soluble polymer binder, thereby enabling the improvement of adhesion between the separator and an electrode, and at the same time, enabling the inhibition of the increasing of the air permeability and resistance of the separator.

Description

Separator for electrochemical devices, method for manufacturing the same, and electrochemical devices including the same

[0001] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0080118, filed June 20, 2024, and Korean Patent Application No. 10-2025-0079349, filed June 17, 2025, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a separator for an electrochemical device, a method for manufacturing the same, and an electrochemical device including the same.

[0003] Electrochemical devices, such as lithium-ion batteries, are rechargeable and dischargeable. They store electrical energy as chemical energy and then release it as electricity when needed. Electrochemical devices typically consist of a cathode, anode, a separator, and an electrolyte.

[0004] Among the components of electrochemical devices, the separator comprises a porous polymer substrate located between the anode and cathode. It isolates the anode and cathode, prevents electrical short-circuiting between the two electrodes, and allows the passage of electrolytes and ions. While the separator itself does not participate in electrochemical reactions, its physical properties, such as wettability with electrolyte, degree of porosity, and thermal shrinkage, influence the performance and safety of the electrochemical device.

[0005] The present invention provides a separator for an electrochemical device, which can improve the adhesive strength of a separator and an electrode by providing an adhesive layer containing a small amount of a water-soluble polymer binder on a coating layer, a method for manufacturing the same, and an electrochemical device including the same.

[0006] However, the problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0007] One embodiment of the present invention provides a separator for an electrochemical device, comprising: a porous polymer substrate; a coating layer provided on at least one surface of the porous polymer substrate and including inorganic particles; and an adhesive layer on the coating layer, the adhesive layer including a first polymer binder and a second polymer binder, wherein the first polymer binder is a water-soluble polymer binder.

[0008] According to one embodiment of the present invention, the second polymer binder may be a water-insoluble polymer binder.

[0009] According to one embodiment of the present invention, the content ratio of the first polymer binder and the second polymer binder may be about 1:99 to 19:81.

[0010] According to one embodiment of the present invention, the first polymer binder may be one selected from polyacrylic acid (PAA), polyacrylamide (PAM), polyvinyl alcohol (PVA), phosphate ester copolymer, phosphate acrylic copolymer, and polyacrylate copolymer.

[0011] According to one embodiment of the present invention, the second polymer binder may be a polyvinylidene-based binder or an acrylic-based binder.

[0012] According to one embodiment of the present invention, the content of the inorganic particles in the coating layer may be about 80 parts by weight or more with respect to 100 parts by weight of the coating layer.

[0013] According to one embodiment of the present invention, the thickness ratio of the coating layer and the adhesive layer may be about 1:1 to 3:1.

[0014] According to one embodiment of the present invention, the thickness of the coating layer may be about 5.0 ㎛ or less.

[0015] According to one embodiment of the present invention, the thickness of the adhesive layer may be about 3.0 ㎛ or less.

[0016] According to one embodiment of the present invention, the adhesive strength of the separator may be about 10 gf / 20 mm or more.

[0017] According to one embodiment of the present invention, the air permeability of the separation membrane may be about 100 sec / 100cc or less.

[0018] According to one embodiment of the present invention, the resistance (Ω) of the separator may be about 0.80 or less.

[0019] One embodiment of the present invention provides a method for manufacturing a separator for an electrochemical device, comprising the steps of: preparing a porous polymer substrate; forming a coating layer by coating a slurry containing inorganic particles on at least one surface of the porous polymer substrate; and forming an adhesive layer by coating a slurry containing a first polymer binder and a second polymer binder on the coating layer, wherein the first polymer binder is a water-soluble polymer binder.

[0020] One embodiment of the present invention provides an electrochemical device comprising: an anode; a cathode; a separator interposed between the anode and the cathode; and an electrolyte, wherein the separator is any one of the separators described above.

[0021] According to one embodiment of the present invention, the electrolyte may be an electrolyte containing one solvent selected from ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and combinations thereof.

[0022] According to one embodiment of the present invention, a separator for an electrochemical device can improve the adhesive strength between an electrode and a binder by including a small amount of a water-soluble polymer binder in the adhesive layer.

[0023] A separator for an electrochemical device according to one embodiment of the present invention can improve adhesion to an electrode while suppressing an increase in air permeability and resistance of the separator.

[0024] A method for manufacturing a separator for an electrochemical device according to one embodiment of the present invention can improve the adhesive strength between an electrode and a separator and suppress an increase in air permeability and resistance of the separator.

[0025] An electrochemical device according to one embodiment of the present invention can improve battery performance.

[0026] The following drawings attached to this specification illustrate embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0027] Figure 1 is a schematic diagram of a separator for an electrochemical device according to one embodiment of the present invention.

[0028] In some of the attached drawings, corresponding components are given the same reference numerals whenever possible, but different reference numerals may be used where necessary. Those skilled in the art will appreciate that the drawings illustrate elements simply and clearly and are not necessarily drawn to scale. For example, to facilitate understanding of various embodiments, the dimensions of some elements depicted in the drawings may be exaggerated relative to other elements. Furthermore, elements of known technology that are useful or essential in commercially feasible embodiments may often not be depicted so as not to obscure the spirit of various embodiments of the present invention.

[0029] In this specification, when a part is said to "include" a certain component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0030] In this specification, “A and / or B” means “A and B, or A or B.”

[0031] In this specification, when it is said that a component is “on”, this does not exclude other components being placed therebetween, unless otherwise specifically stated, but rather means that other components may be placed thereon.

[0032] In this specification, the characteristic of having pores means that the object includes a plurality of pores and that the pores are interconnected with each other, thereby allowing gaseous and / or liquid fluids to pass from one side of the object to the other side.

[0033] In this specification, the separator has a porous characteristic including a large number of pores, and acts as a porous ion-conducting barrier that allows ions to pass while blocking electrical contact between the cathode and the anode in an electrochemical device.

[0034] To enhance the physical properties of a separator, a component of an electrochemical device, methods have been attempted to modify the properties of the coating layer by adding a coating layer to a porous polymer substrate and adding various substances to the coating layer. For example, inorganic substances may be added to the coating layer to enhance the mechanical strength of the separator, or inorganic substances or hydrates may be added to the coating layer to enhance the flame retardancy and heat resistance of the polymer substrate.

[0035] If adhesion of the separator and electrode is possible, it can be applied to assembly processes such as lamination and hot press, and has the advantage of being able to closely contact the electrode interface and separator and secure the strength of the battery cell even under electrolyte injection.

[0036] To bond the separator and electrode, an adhesive layer can be coated on the surface of the separator. Several polymers are used for this adhesive layer. For example, water-insoluble polymer compounds can be used as binders for the adhesive layer. These binders can be dispersed in water through emulsions, suspension polymerization, or post-processing. However, these binders, which are in the form of droplets, have limitations in enhancing the adhesion between the electrode and the separator.

[0037] In the present invention, a separator is provided that overcomes the problems of water-insoluble polymer compounds used as binders for adhesive layers, thereby improving adhesive strength with electrodes and suppressing air permeability and resistance increase.

[0038] Hereinafter, the present invention will be described in more detail with reference to the attached drawings.

[0039] Figure 1 is a schematic diagram of a separator for an electrochemical device according to one embodiment of the present invention.

[0040] An electrochemical device separator (100) according to one embodiment of the present invention comprises: a porous polymer substrate (110); a coating layer (130) provided on at least one surface of the porous polymer substrate and including inorganic particles; and an adhesive layer (150) including a first polymer binder (151) and a second polymer binder (153) on the coating layer; wherein the first polymer binder (151) is a water-soluble polymer binder.

[0041] According to one embodiment of the present invention, a separator (100) for an electrochemical device can improve the adhesive strength between an electrode and the binder by including a small amount of a water-soluble polymer binder in the adhesive layer (150). In addition, according to one embodiment of the present invention, a separator (100) for an electrochemical device can improve the adhesive strength with the electrode while suppressing an increase in the air permeability and resistance of the separator.

[0042] According to one embodiment of the present invention, the separator (100) for an electrochemical device includes a porous polymer substrate (110). As described above, the separator (100) for an electrochemical device includes a porous polymer substrate, thereby allowing lithium ions to pass through while blocking electrical contact, and implementing a shutdown function at an appropriate temperature.

[0043] According to one embodiment of the invention, the porous polymer substrate (110) may be manufactured using a polyolefin-based resin as a base resin. Examples of the polyolefin-based resin include polyethylene, polypropylene, polypentene, etc., and the porous polymer substrate may include one or more of these. A porous membrane, for example, having a large number of pores, manufactured using such a polyolefin-based resin as a base resin is advantageous in terms of imparting a shutdown function at an appropriate temperature.

[0044] According to one embodiment of the present invention, the weight average molecular weight of the polyolefin resin may be about 500,000 or more and 1.5 million or less. By controlling the weight average molecular weight of the polyolefin resin within the above-described range, the compression resistance of the separator can be improved. Furthermore, when different types of polyolefin resins are mixed and used or the separator is formed with a multilayer structure made of different types of polyolefin resins, the weight average molecular weight of the polyolefin resin can be calculated by adding the weight average molecular weight according to the content ratio of each polyolefin resin.

[0045] In the present invention, the weight average molecular weight (Mw) can be measured by gel permeation chromatography (GPC: gel permeation chromatography, PL GPC220, Agilent Technologies), and the measurement conditions can be set as follows.

[0046] - Column: PL Olexis (Polymer Laboratories)

[0047] - Solvent: TCB (Trichlorobenzene)

[0048] - Flow rate: 1.0 ml / min

[0049] - Sample concentration: 1.0 mg / ml

[0050] - Injection volume: 200 ㎕

[0051] - Column temperature: 160 ℃

[0052] - Detector: Agilent High Temperature RI detector

[0053] - Standard: Polystyrene (corrected with a cubic function)

[0054] According to one embodiment of the present invention, the porous polymer substrate (110) may be manufactured by a method (wet method) of mixing a polyolefin resin with a plasticizer (diluent) at a high temperature to form a single phase, separating the polymer material and the plasticizer during a cooling process, extracting the plasticizer to form pores, and then performing stretching and heat-setting.

[0055] According to one embodiment of the present invention, the average pore size and the maximum pore size of the electrochemical device separator (100) can be easily manufactured by a person skilled in the art to conform to the scope of the present invention by controlling the mixing ratio of the plasticizer, the stretching ratio, the heat-setting treatment temperature, etc.

[0056] According to one embodiment of the present invention, the electrochemical device separator (100) includes a coating layer (130) provided on at least one surface of the porous polymer substrate (110). For example, the electrochemical device separator (100) includes a coating layer (130) provided on one or both surfaces of the porous polymer substrate (110). As described above, since the electrochemical device separator (100) includes the coating layer (130) provided on at least one surface of the porous polymer substrate (110), the heat resistance of the separator (100) can be improved, mechanical properties can be improved, and an electrical short circuit can be prevented or suppressed from occurring at an electrode due to shrinkage of the separator (100) at high temperatures.

[0057] According to one embodiment of the present invention, the coating layer (130) includes inorganic particles. As described above, by including the inorganic particles in the coating layer (130), the heat resistance of the separator (100) is improved, the mechanical properties are improved, the shrinkage of the separator at high temperatures is prevented or suppressed from causing an electrical short circuit in the electrode, and pores can be formed within the coating layer (130).

[0058] According to one embodiment of the present invention, the coating layer (130) may further include a third polymer binder. As described above, by including the third polymer binder and the inorganic particles, the coating layer (130) improves the heat resistance of the separator (100), improves the mechanical properties, prevents or suppresses the shrinkage of the separator at high temperatures, causing an electrical short circuit of the electrode, and forms pores within the coating layer (130).

[0059] According to one embodiment of the present invention, the coating layer (130) may be formed by inorganic particles being bound by third polymer binder particles and accumulated within the side. The pores within the coating layer (130) may be derived from interstitial volume, which is an empty space between the inorganic particles.

[0060] According to one embodiment of the present invention, the coating layer (130) may include a plurality of pores. For example, the coating layer (130) may be a porous coating layer. According to one embodiment, the coating layer (130) may be a porous coating layer including a plurality of pores therein. As described above, since the coating layer (130) includes a plurality of pores, it can physically block the negative electrode and the positive electrode while allowing lithium ions to pass through and current to flow.

[0061] According to one embodiment of the present invention, the third polymer binder may be a water-soluble or water-insoluble polymer binder. By selecting the first polymer binder from the above-described ones, the porosity and air permeability of the coating layer can be controlled, the pore size of the coating layer (130) can be controlled, and the mechanical properties of the coating layer (130) can be improved.

[0062] According to one embodiment of the present invention, the third polymer binder may be an acrylic binder, a polyvinylidene binder, or a combination thereof. As described above, by selecting the first polymer binder from the above-described binders, the heat resistance of the coating layer (130) can be improved, and the bonding strength of the inorganic particles within the coating layer (130) can be improved.

[0063] According to one embodiment of the present invention, the third polymer binder may be an acrylic binder. This can maintain the porosity of the separator (100), improve the adhesive strength between the electrode and the separator (100) during the battery lamination process, thereby improving the ease of battery manufacturing, and stably implementing the stacking process.

[0064] According to one embodiment of the present invention, the acrylic binder is a polymer containing a carboxylic acid ester as a repeating unit, for example, (meth)acrylic acid ester or an acrylic-styrene copolymer.

[0065] According to one embodiment of the present invention, the (meth)acrylic acid ester is methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, n-amyl (meth)acrylate, i-amyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, hydroxymethyl (meth)acrylate, hydroxyethyl (meth)acrylate, ethylene glycol (meth)acrylate, di(meth)acrylate, propylene glycol (meth)acrylate, Examples thereof include trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, allyl (meth)acrylate, and ethylene di(meth)acrylate, and the like, and may be at least one selected from these. Among these, the compound may be at least one selected from methyl (meth)acrylate, ethyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate, and according to one embodiment, it may be methyl (meth)acrylate.

[0066] According to one embodiment of the present invention, the acrylic-styrene copolymer may include an acrylic binder, and the acrylic binder may be a polyacrylate. For example, the binder may be at least one selected from styrene-butadiene rubber, nitrile-butadiene rubber, acrylonitrile-butadiene rubber, acrylonitrile-butadiene-styrene rubber, and an acrylate polymer, and more specifically, may be a copolymer including acrylate.

[0067] According to one embodiment of the present invention, the polyvinylidene-based binder included in the third polymer binder may be a polyvinylidene difluoride (PVdF)-based binder. As described above, by selecting the polyvinylidene-based binder as a polyvinylidene difluoride-based binder, the resistance of the separator (100) can be reduced.

[0068] According to one embodiment of the present invention, the polyvinylidene-based binder may be a copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF-co-HFP, Poly(vinylidene fluoride-co-hexafluoropropylene)). As described above, by selecting the polyvinylidene-based binder as a copolymer of polyvinylidene fluoride and hexafluoropropylene, the dissolution of the polymer binder by the electrolyte can be minimized.

[0069] According to one embodiment of the present invention, the polyvinylidene-based binder included in the third polymer binder may have a hexafluoropropylene content of about 5 wt% or more. For example, the polyvinylidene-based binder included in the third polymer binder may have a hexafluoropropylene content of about 5 wt% or more and 80 wt% or less, about 15 wt% or more and 75 wt% or less, about 20 wt% or more and 70 wt% or less, about 25 wt% or more and 65 wt% or less, about 30 wt% or more and 60 wt% or less, about 35 wt% or more and 55 wt% or less, or about 40 wt% or more and 50 wt% or less. By controlling the content of hexafluoropropylene included in the polyvinylidene-based binder in the third polymer binder within the above-described range, the resistance of the separator (100) can be reduced. The content of the above hexafluoropropylene (HFP) monomer is 1 H-NMR and / or 19 It can be measured by F-NMR.

[0070] According to one embodiment of the invention, the third polymer binder may be a hybrid binder particle comprising an acrylic binder and a polyvinylidene binder. As described above, by selecting the third polymer binder as a hybrid binder particle comprising an acrylic binder and a polyvinylidene binder, the adhesive strength with the electrode can be improved.

[0071] According to one embodiment of the present invention, the content of the third polymer binder may be about 20 parts by weight or less with respect to 100 parts by weight of the coating layer. For example, the content of the third polymer binder may be about 0 to 20 parts by weight, about 1 to 15 parts by weight, about 2 to 10 parts by weight, about 2 to 8 parts by weight, or about 2 to 5 parts by weight, with respect to 100 parts by weight of the coating layer (130). By controlling the content of the third polymer binder within the above-described range, the mechanical properties of the coating layer can be improved, the porosity of the coating layer can be maintained, and the heat resistance can be improved.

[0072] According to one embodiment of the present invention, the content of the inorganic particles that can be used in the coating layer (130) may be about 80 parts by weight or more with respect to 100 parts by weight of the coating layer (130). For example, the content of the inorganic particles may be about 80 parts by weight or more and less than 100 parts by weight, 83 parts by weight or more and 99 parts by weight or less, 85 parts by weight or more and 98 parts by weight or less, 90 parts by weight or more and 98 parts by weight or less, or 95 parts by weight or more and 97 parts by weight or less with respect to 100 parts by weight of the coating layer. By controlling the content of the inorganic particles within the above-described range, the heat resistance and mechanical properties of the separation membrane (100) can be improved.

[0073] According to one embodiment of the present invention, the inorganic particles that can be used in the coating layer (130) are not particularly limited as long as they are electrochemically stable. That is, the inorganic particles that can be used in one embodiment of the present invention are those that can be used in 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 V to 5 V (as a reference).

[0074] According to one embodiment of the present invention, non-limiting examples of the inorganic particles that can be used in the coating layer (130) include BaTiO3, Pb(Zr,Ti)O3(PZT), b 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, Mg(OH)2, NiO, CaO, ZnO, ZrO2, SiO2, Y2O3, Al2O3, SiC, Al(OH)3, TiO2, aluminum peroxide, zinc tin hydroxide (ZnSn(OH)6), tin-zinc oxide (Zn2SnO4, ZnSnO3), antimony trioxide (Sb2O3), antimony tetroxide (Sb2O4), antimony pentoxide (Sb2O5), etc., and may include one or more of these.

[0075] According to one embodiment of the present invention, the average diameter (D) of the inorganic particles 50 ) has no special limitations, but may be in the range of about 0.3 ㎛ to 1 ㎛ in order to form a coating layer of uniform thickness and have an appropriate porosity. For example, if it is less than about 0.3 ㎛, the dispersibility of inorganic particles in the slurry prepared for manufacturing the coating layer may be reduced, and if it exceeds about 1 ㎛, the thickness of the formed coating layer may increase.

[0076] In this specification, "D50 particle size" means the particle size at the 50% point of the cumulative distribution of particle numbers according to particle size. The particle size can be measured using a laser diffraction method. For example, after the powder to be measured is dispersed in a dispersion medium, it is introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500), and when the particles pass through the laser beam, the difference in the diffraction pattern according to particle size is measured to calculate the particle size distribution. By calculating the particle diameter at the point where the cumulative distribution of particle numbers according to particle size in the measuring device becomes 50%, the D50 particle size can be measured.

[0077] According to one embodiment of the present invention, the thickness of the coating layer (130) on one side of the porous polymer substrate (110) may be about 5.0 ㎛ or less. For example, the thickness of the coating layer (130) may be about 0 ㎛ or more and 5.0 ㎛ or less, about 0.5 ㎛ or more and 4.5 ㎛ or less, about 1.0 ㎛ or more and 4.0 ㎛ or less, about 1.2 ㎛ or more and 3.8 ㎛ or less, about 1.4 ㎛ or more and 3.6 ㎛ or less, about 1.5 ㎛ or more and 3.5 ㎛ or less, about 1.7 ㎛ or more and 3.4 ㎛ or less, about 2.0 ㎛ or more and 3.3 ㎛ or less, about 2.2 ㎛ or more and 3.2 ㎛ or less, or about 2.5 ㎛ or more and 3.1 ㎛ or less. By controlling the thickness of the coating layer within the above-described range, the heat resistance of the separator (100) can be improved and the energy density can be increased.

[0078] According to one embodiment of the present invention, the electrochemical device separator (100) includes an adhesive layer (150) provided on the coating layer (130). As described above, since the electrochemical device separator (100) includes an adhesive layer (150) provided on the coating layer (130), adhesive strength between the electrode and the separator (100) can be secured during the lamination process of the separator (100) and the electrode.

[0079] According to one embodiment of the present invention, an adhesive layer (150) including a first polymer binder (151) and a second polymer binder (153) is included on the coating layer (130). According to one embodiment, the first polymer binder includes a water-soluble polymer binder. As described above, by the adhesive layer (150) including the first polymer binder which is a water-soluble polymer binder, the adhesive strength between the electrode and the separator (100) can be improved. Furthermore, the adhesive strength between the separator (100) and the electrode is improved, and at the same time, an increase in the air permeability and resistance of the separator (100) can be suppressed.

[0080] According to one embodiment of the present invention, the second polymer binder (153) may be a water-insoluble polymer binder. The water-insoluble polymer binder may refer to a binder dispersed in water through an emulsion or suspension polymerization or through post-processing. As described above, the second polymer binder can maintain the porosity of the adhesive layer and improve the adhesive strength with the electrode by including the water-insoluble polymer binder.

[0081] According to one embodiment of the present invention, the particle size (D50) of the second polymer binder (153) may be in a range of about 0.2 μm or more and 1 μm or less. Within this range, the dispersibility of the second polymer binder in the slurry prepared for producing an adhesive layer can be maintained, and an increase in the thickness of the formed adhesive layer can be prevented or suppressed.

[0082] According to one embodiment of the present invention, the content ratio of the first polymer binder (151) and the second polymer binder (153) may be about 1:99 to 19:81. For example, the content ratio of the first polymer binder and the second polymer binder may be about 1:99 to 18:82, about 1:99 to 17:83, about 1:99 to 16:84, about 1:99 to 15:85, about 1:99 to 14:86, about 1:99 to 13:87, about 1:99 to 12:88, or about 1:99 to 11:89, and according to one embodiment, about 1:99 to 10:90. In the above-described range, an increase in the air permeability and resistance of the separator may be suppressed, and the adhesive strength between the separator and the electrode may be improved.

[0083] According to one embodiment of the present invention, the first polymer binder (151) may be one selected from polyacrylic acid (PAA), polyacrylamide (PAM), polyvinyl alcohol (PVA), phosphate ester-based copolymers, phosphate acrylic-based copolymers, polyacrylate-based copolymers, and combinations thereof. According to one embodiment, the first polymer binder may be polyacrylic acid (PAA). By selecting the first polymer binder within the above-described range, the adhesive strength of the separator can be improved.

[0084] According to one embodiment of the present invention, the second polymer binder (153) may be a polyvinylidene-based binder or an acrylic-based binder.

[0085] According to one embodiment of the present invention, the second polymer binder (153) may be an acrylic binder. This can maintain the porosity of the separator (100), improve the adhesive strength between the electrode and the separator (100) during the lamination process of the battery, thereby improving the ease of battery manufacturing, and stably implementing the stacking process.

[0086] According to one embodiment of the present invention, the acrylic binder is a polymer containing a carboxylic acid ester as a repeating unit, for example, (meth)acrylic acid ester or an acrylic-styrene copolymer.

[0087] According to one embodiment of the present invention, the (meth)acrylic acid ester is methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, n-amyl (meth)acrylate, i-amyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, hydroxymethyl (meth)acrylate, hydroxyethyl (meth)acrylate, ethylene glycol (meth)acrylate, di(meth)acrylate, propylene glycol (meth)acrylate, Examples thereof include trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, allyl (meth)acrylate, and ethylene di(meth)acrylate, and the like, and may be at least one selected from these. Among these, the example may be at least one selected from methyl (meth)acrylate, ethyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate, and may be, for example, methyl (meth)acrylate.

[0088] According to one embodiment of the present invention, the acrylic-styrene copolymer may include an acrylic binder, and the acrylic binder may be a polyacrylate. For example, the binder may be at least one selected from styrene-butadiene rubber, nitrile-butadiene rubber, acrylonitrile-butadiene rubber, acrylonitrile-butadiene-styrene rubber, and an acrylate polymer, and more specifically, may be a copolymer including an acrylate.

[0089] According to one embodiment of the present invention, the polyvinylidene-based binder included in the second polymer binder (153) may be a polyvinylidene difluoride (PVdF)-based binder. As described above, by selecting the polyvinylidene-based binder as a polyvinylidene difluoride-based binder, the resistance of the separator (100) can be reduced.

[0090] According to one embodiment of the present invention, the polyvinylidene-based binder may be a copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF-co-HFP, Poly(vinylidene fluoride-co-hexafluoropropylene)). As described above, by selecting the polyvinylidene-based binder as a copolymer of polyvinylidene fluoride and hexafluoropropylene, the dissolution of the polymer binder by the electrolyte can be minimized.

[0091] According to one embodiment of the present invention, the polyvinylidene-based binder included in the second polymer binder (153) may have a hexafluoropropylene content of about 5 wt% or more. For example, the polyvinylidene-based binder included in the third polymer binder may have a hexafluoropropylene content of about 10 wt% or more and 80 wt% or less, about 15 wt% or more and 75 wt% or less, about 20 wt% or more and 70 wt% or less, about 25 wt% or more and 65 wt% or less, about 30 wt% or more and 60 wt% or less, about 35 wt% or more and 55 wt% or less, or about 40 wt% or more and 50 wt% or less. By controlling the content of hexafluoropropylene included in the polyvinylidene-based binder in the third polymer binder within the above-described range, the resistance of the separator (100) can be reduced. The content of the above hexafluoropropylene (HFP) monomer is 1 H-NMR and / or 19 It can be measured by F-NMR.

[0092] According to one embodiment of the present invention, the thickness of the adhesive layer (150) may be about 3.0 ㎛ or less. For example, the thickness of the adhesive layer may be about 0 ㎛ or more and 3.0 ㎛ or less, about 0.1 ㎛ or more and 2.8 ㎛ or less, about 0.2 ㎛ or more and 2.6 ㎛ or less, about 0.3 ㎛ or more and 2.4 ㎛ or less, about 0.4 ㎛ or more and 2.2 ㎛ or less, about 0.5 ㎛ or more and 2.0 ㎛ or less, about 0.6 ㎛ or more and 1.8 ㎛ or less, about 0.7 ㎛ or more and 1.6 ㎛ or less, about 0.8 ㎛ or more and 1.4 ㎛ or less, about 0.9 ㎛ or more and 1.2 ㎛ or less, or about 0.9 ㎛ or more and 1.1 ㎛ or less. By controlling the thickness of the adhesive layer (150) within the above-described range, the adhesive strength between the separator (100) and the electrode can be improved, and the increase in air permeability and resistance of the separator can be suppressed.

[0093] According to one embodiment of the present invention, the thickness ratio of the coating layer (130) and the adhesive layer (150) may be about 1:1 to 3:1. By controlling the thickness ratio of the coating layer (130) and the adhesive layer (150) within the above-described range, it is possible to contribute to thinning of the separator and suppress an increase in the air permeability and resistance of the separator.

[0094] According to one embodiment of the present invention, the adhesive strength of the separator (100) may be about 10 gf / 20 mm or more. For example, the adhesive strength of the separator (100) may be about 10 gf / 20 mm or more and 60 gf / 20 mm or less, about 20 gf / 20 mm or more and 60 gf / 20 mm or less, about 30 gf / 20 mm or more and 60 gf / 20 mm or less, or about 30 gf / 20 mm or more and 50 gf / 20 mm or less. By controlling the adhesive strength of the separator (100) within the above-described range, the performance of the battery can be improved.

[0095] According to one embodiment of the present invention, the air permeability of the separator (100) may be about 100 sec / 100cc or less. For example, the air permeability of the separator (100) may be about 80 sec / 100cc or more and 100 sec / 100cc or less, about 82 sec / 100cc or more and 99 sec / 100cc or less, about 84 sec / 100cc or more and 98 sec / 100cc or less, about 85 sec / 100cc or more and 98 sec / 100cc or less, about 86 sec / 100cc or more and 98 sec / 100cc or less, or about 88 sec / 100cc or more and 97 sec / 100cc or less. By controlling the air permeability of the separator (100) within the above-described range, the performance of the battery can be improved.

[0096] According to one embodiment of the present invention, the resistance (Ω, ohm) of the separator (100) may be about 0.80 ohm or less. For example, the resistance of the separator (100) may be about 0.60 ohm or more and 0.80 ohm or less, about 0.65 ohm or more and 0.80 ohm or less, about 0.70 ohm or more and 0.80 ohm or less, about 0.70 ohm or more and 0.78 ohm or less, about 0.72 ohm or more and 0.78 ohm or less, or about 0.72 ohm or more and 0.77 ohm or less. By controlling the resistance of the separator (100) within the above-described range, the performance of the battery can be improved.

[0097] One embodiment of the present invention includes a method for manufacturing a separator (100) for an electrochemical device, comprising the steps of: preparing a porous polymer substrate (110); forming a coating layer (130) by coating a slurry containing inorganic particles on at least one surface of the porous polymer substrate (110); and forming an adhesive layer (150) by coating a slurry containing a first polymer binder (151) and a second polymer binder (153) on the coating layer (130), wherein the first polymer binder (151) is a water-soluble polymer binder.

[0098] The method for manufacturing a separator (100) for an electrochemical device according to one embodiment of the present invention can improve the adhesive strength between an electrode and a separator (100) and suppress an increase in air permeability and resistance of the separator (100). In the method for manufacturing a separator (100) for an electrochemical device according to one embodiment of the present invention, any content that overlaps with the description of the separator (100) for an electrochemical device will be omitted.

[0099] According to one embodiment of the present invention, the method for manufacturing the electrochemical device separator (100) includes a step of applying a slurry containing inorganic particles to at least one surface of a porous polymer substrate (110). As described above, by including the step of applying a slurry containing inorganic particles to at least one surface of the porous polymer substrate (110), a coating layer (130) can be formed, and the content of inorganic particles in the slurry for the coating layer is excessive, thereby improving the heat resistance of the separator (100).

[0100] According to one embodiment of the present invention, the method for applying the slurry for the coating layer to the surface of the porous polymer substrate (110) is not particularly limited to any one method, and a conventional method known in the art may be used. For example, various methods such as dip coating, die coating, roll coating, comma coating, bar coating, or a mixture thereof may be used.

[0101] According to one embodiment of the present invention, the slurry for the coating layer may further include a third polymer binder. As described above, the slurry for the coating layer can control the density difference between the polymer binder particles and the inorganic particles by further including the third polymer binder, and can improve the adhesive strength between the separator (100) and the electrode by including the polymer binder particles.

[0102] According to one embodiment of the present invention, prior to the step of applying the slurry for the coating layer, a polymer solution may be prepared by dissolving a third polymer binder in an appropriate solvent to prepare a slurry. The solvent may have a solubility index similar to that of the polymer binder to be used and a low boiling point. This is to facilitate uniform mixing and subsequent solvent removal. Non-limiting examples of solvents that can be used include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or mixtures thereof.

[0103] According to one embodiment of the present invention, prior to the step of applying the slurry for the coating layer, a polymer emulsion may be prepared by dispersing a third polymer binder in an appropriate dispersion medium to prepare a slurry. A material having a low boiling point may be selected as the dispersion medium. This is to facilitate uniform mixing and subsequent removal of the dispersion medium. Non-limiting examples of usable dispersion mediums include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or mixtures thereof.

[0104] According to one embodiment of the present invention, inorganic particles may be added and dispersed in the polymer emulsion or polymer solution. The content ratio of the inorganic particles and the polymer binder particles is as described above, and may be appropriately adjusted in consideration of the thickness, pore size, and porosity of the coating layer to be finally manufactured according to one embodiment of the present invention.

[0105] According to one embodiment of the present invention, the solid content of the slurry for the coating layer may be about 10 wt% or more and 40 wt% or less. For example, the solid content of the slurry for the coating layer may be about 11 wt% or more and 38 wt% or less, about 12 wt% or more and 36 wt% or less, about 13 wt% or more and 34 wt% or less, about 14 wt% or more and 32 wt% or less, about 15 wt% or more and 30 wt% or less, about 16 wt% or more and 28 wt% or less, about 17 wt% or more and 26 wt% or less, about 18 wt% or more and 24 wt% or less, or about 19 wt% or more and 22 wt% or less. By controlling the solid content of the slurry for the coating layer within the above-described range, an increase in the resistance of the separator can be prevented or suppressed, and the separator can be manufactured into a thin film to improve the energy density of the battery.

[0106] According to one embodiment of the present invention, the method for manufacturing the electrochemical device separator (100) includes a step of applying a slurry containing a first polymer binder and a second polymer binder onto the coating layer (130). As described above, by including the step of applying a slurry containing the first polymer binder and the second polymer binder onto the coating layer (130), an adhesive layer can be easily formed, thereby implementing adhesive strength between the separator (100) and the electrode.

[0107] According to one embodiment of the present invention, the method of applying the slurry for the adhesive layer onto the coating layer (130) is not particularly limited to any one method, and a conventional method known in the art may be used. For example, various methods such as dip coating, die coating, roll coating, comma coating, bar coating, or a mixture thereof may be used.

[0108] According to one embodiment of the present invention, the slurry for the adhesive layer may further include a dispersion medium, and the dispersion medium may be water. As described above, by the slurry for the adhesive layer further including a dispersion medium, the second polymer binder can be uniformly dispersed.

[0109] According to one embodiment of the present invention, the method for manufacturing the electrochemical device separator (100) may include a step of drying the slurry for the coating layer to form a coating layer (130). By including the step of drying the slurry for the coating layer to form a coating layer (130) as described above, damage to the coating layer (130) can be minimized, and the solvent or dispersion medium included in the slurry can be easily removed.

[0110] According to one embodiment of the present invention, the method for manufacturing the separator (100) for an electrochemical device may include a step of drying the slurry for the adhesive layer to form an adhesive layer (150). By including the step of drying the slurry for the adhesive layer to form an adhesive layer (150) as described above, damage to the adhesive layer (150) can be minimized, and the dispersion medium included in the slurry can be easily removed.

[0111] According to one embodiment of the present invention, the method for manufacturing the electrochemical device separator (100) may include a step of applying and drying the slurry for the coating layer, and then drying the slurry for the adhesive layer to form a coating layer (130) and an adhesive layer (150), respectively. As described above, by including a step of applying and drying the slurry for the coating layer, and then drying the slurry for the adhesive layer to form a coating layer (130) and an adhesive layer (150), respectively, the coating layer (130) and the adhesive layer (150) can be easily formed.

[0112] According to one embodiment of the present invention, the drying process appropriately sets time conditions so as to minimize the occurrence of surface defects in the coating layer (130). The drying may be performed using a drying auxiliary device such as a drying oven or hot air within an appropriate range.

[0113] According to one embodiment of the present invention, the separator (100) is interposed between the negative electrode and the positive electrode and is manufactured into an electrode assembly through a lamination process that applies heat and / or pressure to bond them. In one embodiment of the present invention, the lamination process can be performed by a roll press device including a pair of pressure rollers. For example, the negative electrode, the separator (100), and the positive electrode can be sequentially laminated and placed between the pressure rollers to achieve interlayer bonding. At this time, the lamination process can be performed by a hot press method.

[0114] One embodiment of the present invention includes an electrochemical device comprising: an anode; a cathode; a separator interposed between the anode and the cathode; and an electrolyte, wherein the separator is any one of the separators described above.

[0115] An electrochemical device according to one embodiment of the present invention can improve battery performance.

[0116] In this specification, the cylindrical secondary battery, which is an electrochemical device, is a device that converts chemical energy into electrical energy through an electrochemical reaction, and is a concept encompassing a primary battery and a secondary battery. In this specification, the secondary battery is capable of charging and discharging, and refers to a lithium secondary battery, a nickel-cadmium battery, a nickel-hydrogen battery, etc. The lithium secondary battery uses lithium ions as an ion conductor, and examples thereof include, but are not limited to, a non-aqueous electrolyte secondary battery including a liquid electrolyte, an all-solid-state battery including a solid electrolyte, a lithium polymer battery including a gel polymer electrolyte, and a lithium metal battery using lithium metal as an anode.

[0117] According to one embodiment of the present invention, the positive electrode has a positive electrode current collector and a positive electrode active material layer including a positive electrode active material, a conductive material, and a binder resin on at least one surface of the positive electrode current collector. The positive electrode active material is a layered compound such as lithium manganese oxide (LiMn2O4, LiMnO2, etc.), lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; chemical formula Li 1+x Mn 2-x Lithium manganese oxides such as O4 (where x is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, Cu2V2O7; chemical formula LiNi 1-x M x Ni-site type lithium nickel oxide represented by O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga and x = 0.01 to 0.3); chemical formula LiMn1-xM xA lithium manganese composite oxide represented by O2 (wherein, M = Co, Ni, Fe, Cr, Zn or Ta, and x = 0.01 to 0.1) or Li2Mn3MO8 (wherein, M = Fe, Co, Ni, Cu or Zn); LiMn2O4 in which a portion of Li in the chemical formula is replaced by an alkaline earth metal ion; a disulfide compound; or a mixture of two or more of Fe2(MoO4)3.

[0118] According to one embodiment of the present invention, the negative electrode has a negative electrode current collector and a negative electrode active material layer including a negative electrode active material, a conductive material, and a binder resin on at least one surface of the current collector. The negative electrode includes carbon such as lithium metal oxide, non-graphitizable carbon, and graphite carbon as the negative electrode active material; LixFe2O3(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; 규소계 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 중 선택된 1종 또는 2종 이상의 혼합물을 포함할 수 있다.

[0119] According to one embodiment of the present invention, the conductive material may be, for example, one selected from graphite, carbon black, carbon fibers or metal fibers, metal powders, conductive whiskers, conductive metal oxides, activated carbon, and polyphenylene derivatives, or a mixture of two or more conductive materials thereof. According to one embodiment, the conductive material may be one selected from natural graphite, artificial graphite, super-p, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black, Denka black, aluminum powder, nickel powder, zinc oxide, potassium titanate, and titanium oxide, or a mixture of two or more conductive materials thereof.

[0120] According to one embodiment of the present invention, the current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, stainless steel, copper, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. can be used.

[0121] According to one embodiment of the present invention, the binder resin may be a polymer commonly used in electrodes in the art. Non-limiting examples of such binder resins include polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-cotrichloroethylene, polymethylmethacrylate, polyethylhexyl acrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate. Examples thereof include, but are not limited to, cellulose acetatepropionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, and carboxyl methyl cellulose.

[0122] In the present invention, the positive electrode slurry for manufacturing the positive electrode active material layer may include a dispersant, and the dispersant may be a pyrrolidone-based compound. For example, it may be N-methylpyrrolidone (ADC-01, LG Chemical).

[0123] According to one embodiment of the present invention, the content of the dispersant included in the positive electrode slurry may be about 0 part by weight or more and 0.5 part by weight or less with respect to 100 parts by weight of the positive electrode slurry. For example, the content of the dispersant included in the positive electrode slurry may be about 0.05 part by weight or more and 0.4 part by weight or less with respect to 100 parts by weight of the positive electrode slurry.

[0124] According to one embodiment of the present invention, the negative electrode slurry for manufacturing the negative electrode active material layer may include a dispersant, and the dispersant may be a polypyrrolidone-based compound. For example, the dispersant may be polyvinylpyrrolidone (Polyvinylpyrrolidone, Junsei, Japan).

[0125] According to one embodiment of the present invention, the content of the dispersant included in the cathode slurry may be about 0 part by weight or more and 0.5 part by weight or less with respect to 100 parts by weight of the cathode slurry. For example, the content of the dispersant included in the cathode slurry may be about 0.05 part by weight or more and 0.4 part by weight or less with respect to 100 parts by weight of the cathode slurry.

[0126] According to one embodiment of the present invention, the electrochemical device may further include an electrolyte.

[0127] According to one embodiment of the present invention, an electrochemical device prepared as described above can be placed in an appropriate case and an electrolyte solution is injected to manufacture a battery.

[0128] According to one embodiment of the present invention, the electrolyte is A + B -As a salt with the same structure as A + is Li + , Na + , K + B containing an ion composed of an alkali metal cation or a combination thereof; - is PF6 - , BF4 - , Cl - , Br - , I - , ClO4 - , AsF6 - , CH3CO2 - , CF3SO3 - , N(CF3SO2)2 - , C(CF2SO2)3 - Salts containing anions such as or combinations thereof are dissolved or dissociated in organic solvents such as propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), gamma butyrolactone (γ-butyrolactone) or mixtures thereof, but are not limited thereto.

[0129] According to one embodiment of the present invention, the electrolyte may include one solvent selected from ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and combinations thereof.

[0130] One embodiment of the present invention provides a battery module including a battery including the electrochemical element as a unit cell, a battery pack including the battery module, and a device including the battery pack as a power source. Examples of the device include, but are not limited to, a power tool that is powered by an electric motor; an electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), etc.; an electric two-wheeled vehicle including an electric bicycle (E-bike) and an electric scooter (E-scooter); an electric golf cart; and a power storage system.

[0131] Hereinafter, the present invention will be described in detail using examples. However, the examples according to the present invention may be modified in various ways, and the scope of the present invention is not limited to the examples described below. The examples in this specification are provided to more fully explain the present invention to those of ordinary skill in the art.

[0132]

[0133] <Example 1>

[0134] Polyethylene resin (weight average molecular weight 900,000) was extruded and a porous polymer substrate (total thickness of approximately 9 ㎛) was manufactured using a wet method.

[0135] Al2O3 powder with a D50 particle size of 500 nm was prepared as an inorganic particle. Acrylic emulsion (CSB-130, Toyo Ink Co., Ltd.) was prepared as a third polymer binder, and sodium carboxymethyl cellulose (CMC-Na) (SG-L02, GL Chem Co., Ltd.) was prepared as a dispersant.

[0136] The above-prepared inorganic particles, third polymer binder, and dispersant were added to water in a weight ratio of 97:2:1, and then the inorganic particles were added, crushed, and dispersed to prepare a slurry for a coating layer.

[0137] The slurry for the coating layer was coated on both sides of the porous polymer substrate and dried to form a coating layer with a thickness of 3 μm.

[0138] A water-soluble polymer, polyacrylic acid (PAA, Miwon Commercial Co., SBS10), and a water-insoluble polymer, PVDF (Arkema, LBG2200), were prepared as the first polymer binder and the second polymer binder, respectively. The first and second polymer binders were prepared in a ratio of 5:95 wt%, and then added to water to prepare a slurry for an adhesive layer with a total solid content of 5%.

[0139] The slurry for the adhesive layer is loaded onto the coating layer at a loading amount of 0.5 to 1.0 g / m 2 After coating, drying was performed to form an adhesive layer with a thickness of 1 ㎛ to manufacture a separator for an electrochemical device.

[0140]

[0141] <Example 2>

[0142] A separator for an electrochemical device was manufactured in the same manner as in Example 1, except that an acrylic emulsion (BM2510, ZEON) was used as the second polymer binder, a water-insoluble polymer.

[0143]

[0144] <Example 3>

[0145] A separator for an electrochemical device was manufactured in the same manner as in Example 2, except that the content of the first polymer binder and the second polymer binder was 10:90.

[0146]

[0147] <Example 4>

[0148] A separator for an electrochemical device was manufactured in the same manner as in Example 2, except that the content of the first polymer binder and the second polymer binder was 1:99.

[0149]

[0150] <Example 5>

[0151] In the above Example 1, a separator for an electrochemical device was manufactured in the same manner as in the above Example 1, except that the thickness of the coating layer was 1 μm and the thickness of the adhesive layer was 1 μm.

[0152]

[0153] <Comparative Example 1>

[0154] A separator for an electrochemical device was manufactured in the same manner as in Example 1, except that polyacrylic acid (PAA) was not used as the water-soluble polymer, which is the first polymer binder.

[0155]

[0156] Comparative Example 2

[0157] A separator for an electrochemical device was manufactured in the same manner as in Example 2, except that polyacrylic acid (PAA) was not used as the water-soluble polymer, which is the first polymer binder.

[0158]

[0159] <Comparative Example 3>

[0160] A separator for an electrochemical device was manufactured in the same manner as in Example 1, except that instead of polyacrylic acid as the water-soluble polymer, which is the first polymer binder, a water-insoluble polymer, an acrylic emulsion (BM2510, ZEON Co., Ltd.) was used.

[0161]

[0162] Comparative Example 4

[0163] A separator for an electrochemical device was manufactured in the same manner as in Example 1, except that the content of the first polymer binder and the second polymer binder was 20:80.

[0164]

[0165] Comparative Example 5

[0166] A separator for an electrochemical device was manufactured in the same manner as in Example 2, except that the content of the first polymer binder and the second polymer binder was 20:80.

[0167]

[0168] <Comparative Example 6>

[0169] In the above Example 1, a separator for an electrochemical device was manufactured in the same manner as in the above Example 1, except that the thickness of the coating layer was 4 μm and the thickness of the adhesive layer was 1 μm.

[0170]

[0171] <Manufacturing of electrochemical devices>

[0172] 1) Manufacturing of the anode

[0173] Cathode active material (LiNi) 0.8 Mn 0.1 Co 0.1 O2), a conductive agent (carbon black), a dispersant (N-methylpyrrolidone, ADC-01, LG Chemical), and a binder resin (a mixture of PVDF-HFP and PVDF) were mixed with water in a weight ratio of 97.5:0.7:0.14:1.66 to prepare a slurry for a cathode active material layer with a concentration of 50 wt% of the remaining components excluding water. Next, the slurry was applied to the surface of an aluminum thin film (thickness 10 μm) and dried to manufacture a cathode having a cathode active material layer (thickness 120 μm).

[0174]

[0175] 2) Manufacturing of cathode

[0176] Graphite (natural graphite and artificial graphite blend), conductive agent (carbon black), dispersant (polyvinylpyrrolidone, Junsei, Japan), and binder resin (PVDF-HFP and PVDF blend) were mixed with water in a weight ratio of 97.5:0.7:0.14:1.66 to prepare a slurry for an anode active material layer with a concentration of 50 wt% of the remaining components excluding water. Next, the slurry was applied to the surface of a copper thin film (thickness 10 μm) and dried to manufacture an anode having an anode active material layer (thickness 120 μm).

[0177]

[0178] 3) Lamination process

[0179] The separators of the examples and comparative examples were interposed between the manufactured cathodes and anodes, and a lamination process was performed to obtain an electrode assembly. The lamination process was performed using a hot press at 60°C and 6.5 MPa for 1 second.

[0180]

[0181] <Experimental Example>

[0182] Electrode-separator adhesion measurement

[0183] The separators of the above examples and comparative examples were cut into 70 mm (length) x 20 mm (width), and the prepared electrodes and separators were laminated using a press under the conditions of 60 ℃, 6.5 MPa, and 1 sec to produce specimens. The prepared specimens were fixed by attaching them to a glass plate using double-sided tape, and at this time, they were positioned so that the electrodes faced the glass plate. The separator portion of the specimen was peeled at an angle of 180° at a speed of 150 mm / min at 25 ℃, and the strength at this time was measured.

[0184]

[0185] Membrane permeability measurement

[0186] The membrane permeability (permeability, Gurley) of the above examples and comparative examples was measured by the ASTM D726-94 method. The permeability used here is the resistance to air flow, which is measured by a Gurley densometer. The permeability value described here is the value obtained when 100 cc of air flows through 1 in of the membrane under a pressure of 12.2 in H2O. 2 The time (in seconds) it takes to pass through the cross section of the tube is expressed as the ventilation time.

[0187]

[0188] Membrane resistance measurement

[0189] The resistance of the above examples and comparative examples was measured by sandwiching each separator substrate between SUS and injecting electrolyte to manufacture coin cells and measuring the resistance (ER) using the EIS method. At this time, the frequency was in the range of 100,000 to 10,000 Hz. The electrolyte is a non-aqueous solvent containing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a 3:7 ratio and LiPF6 mixed at a concentration of 1 M.

[0190]

[0191]

[0192]

[0193] Referring to Table 1 above, it can be confirmed that Examples 1 to 5 according to one embodiment of the present invention have improved adhesion between the electrode and the separator and excellent air permeability and resistance of the separator.

[0194] In this regard, Comparative Examples 1 to 3 confirmed that the adhesive strength between the electrode and the separator was reduced when only a water-insoluble polymer was used. Comparative Examples 4 and 5 confirmed that the air permeability and resistance of the separator increased due to the excessive content of the water-soluble polymer. Comparative Example 6 confirmed that the air permeability and resistance of the separator increased as the coating layer thickness increased relative to the adhesive layer thickness.

[0195] Therefore, the separator (100) for an electrochemical device according to one embodiment of the present invention can improve the adhesive strength between the electrode and the separator (100) by including a small amount of a water-soluble polymer in the adhesive layer (150), and suppress an increase in the air permeability and resistance of the separator (100).

[0196] Although the present disclosure has been described above with reference to embodiments thereof, it will be understood by those skilled in the art or having ordinary knowledge in the art that various modifications and changes to the various embodiments of the present disclosure may be made without departing from the technical scope of the various embodiments of the present disclosure as set forth in the claims below. Accordingly, the technical scope of the various embodiments of the present disclosure should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

[0197] [Explanation of symbols]

[0198] 100: Membrane

[0199] 110: Porous polymer substrate

[0200] 130: Coating layer

[0201] 150: Adhesive layer

[0202] 151: First polymer binder

[0203] 153: Second polymer binder

Claims

1. Porous polymer substrate; A coating layer provided on at least one surface of the porous polymer substrate and including inorganic particles; and An adhesive layer including a first polymer binder and a second polymer binder on the coating layer; A separator for an electrochemical device, wherein the first polymer binder is a water-soluble polymer binder.

2. In claim 1, A separator for an electrochemical device, wherein the second polymer binder is a water-insoluble polymer binder.

3. In claim 1, A separator for an electrochemical device, wherein the content ratio of the first polymer binder and the second polymer binder is 1:99 to 19:

81.

4. In claim 1, A separator for an electrochemical device, wherein the first polymer binder is one selected from polyacrylic acid (PAA), polyacrylamide (PAM), polyvinyl alcohol (PVA), phosphate ester-based polymers, phosphate acrylic-based copolymers, polyacrylate-based copolymers, and combinations thereof.

5. In claim 1, A separator for an electrochemical device, wherein the second polymer binder is a polyvinylidene-based binder or an acrylic-based binder.

6. In claim 1, A separator for an electrochemical device, wherein the content of the inorganic particles in the coating layer is 80 parts by weight or more with respect to 100 parts by weight of the coating layer.

7. In claim 1, A separator for an electrochemical device, wherein the thickness ratio of the coating layer and the adhesive layer is 1:1 to 3:

1.

8. In claim 1, A separator for an electrochemical device, wherein the thickness of the coating layer is 5.0 ㎛ or less.

9. In claim 1, A separator for an electrochemical device, wherein the thickness of the adhesive layer is 3.0 ㎛ or less.

10. In claim 1, A separator for an electrochemical device, wherein the adhesive strength of the separator is 10 gf / 20 mm or more.

11. In claim 1, A separator for an electrochemical device, wherein the air permeability of the above separator is 100 sec / 100cc or less.

12. In claim 1, A separator for an electrochemical device, wherein the resistance of the separator is 0.80 ohm or less.

13. Step of preparing a porous polymer substrate; A step of forming a coating layer by coating a slurry containing inorganic particles on at least one surface of the porous polymer substrate; and A step of forming an adhesive layer by coating a slurry containing a first polymer binder and a second polymer binder on the coating layer; A method for manufacturing a separator for an electrochemical device, wherein the first polymer binder is a water-soluble polymer binder.

14. In an electrochemical device comprising a positive electrode; a negative electrode; a separator interposed between the positive electrode and the negative electrode; and an electrolyte, An electrochemical device, wherein the above separator is the separator of claim 1.

15. In claim 14, An electrochemical device, wherein the electrolyte comprises one solvent selected from ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and combinations thereof.

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