Separator for electrochemical device and electrochemical device comprising same

Abstract

The present invention relates to a separator for an electrochemical device and an electrochemical device comprising same, and specifically, to a separator for an electrochemical device and an electrochemical device comprising same, wherein a plate-shaped silicate-based composition is included in an adhesive layer to improve the dispersibility of a slurry for the adhesive layer, improve the uniformity of the adhesive layer, and reduce the measurement deviation of the adhesive strength and peel strength at each separator position.

Description

Separator for electrochemical devices and electrochemical devices containing the same

[0001] This invention claims the benefit of patent application No. 10-2024-0080117, filed with the Korean Intellectual Property Office on June 20, 2024, and patent application No. 10-2025-0080840, filed with the Korean Intellectual Property Office on June 19, 2025, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a separator for an electrochemical device and an electrochemical device including the same, and more particularly, to a separator for an electrochemical device and an electrochemical device including the same, which can improve the dispersibility of a slurry for an adhesive layer, improve the uniformity of the adhesive layer, and improve the measurement deviation of adhesive strength and peel strength according to the position of the separator by including a plate-shaped silicate composition in the adhesive layer.

[0003] 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.

[0004] Accordingly, various methods have been attempted to enhance the physical properties of the separator by adding a coating layer to a porous polymer substrate and adding various substances to the coating layer to change the properties of the coating layer. For example, an inorganic substance may be added to the coating layer to enhance the mechanical strength of the separator, or an inorganic substance or hydrate may be added to the coating layer to enhance the flame retardancy and heat resistance of the polymer substrate. Furthermore, an adhesive layer may be added on the coating layer and various substances may be added to the adhesive layer to improve the properties of the adhesive layer.

[0005] 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.

[0006] Meanwhile, the adhesive slurry produced during the membrane manufacturing process has a low viscosity, which can lead to phase separation if left at room temperature. Furthermore, the binder particles can clump together, resulting in uneven coating. This can lead to variations in adhesive strength at different locations between the electrode and membrane interfaces, and can also lead to decreased membrane productivity due to frequent filter replacement cycles.

[0007] Therefore, it was necessary to study a separation membrane that could increase the viscosity of the slurry for the adhesive layer centered on low shear conditions rather than increasing the viscosity of the slurry for the adhesive layer under both low shear conditions and high shear conditions, and could improve the phase stability when stored at room temperature.

[0008] The technical problem to be achieved by the present invention is to provide a separator for an electrochemical device, which includes a plate-shaped silicate composition in an adhesive layer included in the separator and can improve the uniformity of the separator by controlling the components and content thereof, and an electrochemical device including the same.

[0009] However, the problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned can be clearly understood by those skilled in the art from the description below.

[0010] 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 a first polymer binder and inorganic particles; and an adhesive layer provided on the coating layer and including a second polymer binder and a plate-like silicate composition; wherein the plate-like silicate composition includes one selected from the group consisting of SiO2, MgO, Li2O, Na2O, and combinations thereof.

[0011] According to one embodiment of the present invention, the adhesive layer may be provided so that a portion of the coating layer is exposed.

[0012] According to one embodiment of the present invention, the coverage (coverage, %) of the adhesive layer may be 90% or more.

[0013] According to one embodiment of the present invention, the plate-shaped silicate composition may contain 50 wt% or more and 60 wt% or less of SiO2.

[0014] According to one embodiment of the present invention, the plate-shaped silicate composition may contain 22 wt% or more and 28 wt% or less of the MgO.

[0015] According to one embodiment of the present invention, the plate-shaped silicate composition may contain Li2O in an amount of 0.5 wt% or more and 2.0 wt% or less.

[0016] According to one embodiment of the present invention, the plate-shaped silicate composition may contain Na2O in an amount of 2.0 wt% or more and 8.0 wt% or less.

[0017] According to one embodiment of the present invention, the content of the plate-shaped silicate composition may be 1 part by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the adhesive layer.

[0018] According to one embodiment of the present invention, the plate-shaped silicate composition may further include P2O5, F, and a combination thereof.

[0019] According to one embodiment of the present invention, the pH of the aqueous suspension containing the plate-shaped silicate composition in an amount of 2 wt% or more and 5 wt% or less may be 8.0 or more and 12.0 or less.

[0020] According to one embodiment of the present invention, the plate-shaped silicate composition may be laponite.

[0021] According to one embodiment of the present invention, when a specimen (20 cm (width) x 30 cm (height)) of the separation membrane is prepared and a force is applied at 180° at a measurement speed of 300 mm / min using a UTM device (LLOYD Instrument LF Plus), the deviation of the peel strength measured at five arbitrary measurement positions within the specimen may be 3 gf / mm or less.

[0022] One embodiment of the present invention provides an electrochemical device comprising: an anode; a cathode; and a separator interposed between the anode and the cathode.

[0023] According to one embodiment of the present invention, when a specimen (20 cm (width) x 30 cm (height)) of the separator is prepared and the separator portion of the specimen is peeled at an angle of 180° at a speed of 150 mm / min at 25°C, the deviation of the adhesive strength between the separator and the negative electrode measured at five arbitrary measurement positions within the specimen may be 4 gf / mm or less.

[0024] The separator for an electrochemical device according to one embodiment of the present invention can improve coating uniformity by preventing components included in the adhesive layer from being unevenly distributed during adhesive layer coating.

[0025] An electrochemical device according to one embodiment of the present invention can improve the performance of a battery by improving the coating uniformity of an adhesive layer.

[0026] Figure 1 is a schematic diagram of a separator for an electrochemical device according to one embodiment of the present invention.

[0027] Figure 2 is a photograph showing whether phase separation occurred in the slurry for the adhesive layer of Comparative Example 1 (A) and Example 1 (B) of the present invention.

[0028] Figure 3 is a photograph showing whether phase separation occurred in the slurry for the adhesive layer of Comparative Example 1 (A), Example 2 (C), and Example 3 (D) of the present invention.

[0029] Figure 4 shows the measurement positions of adhesive strength and peel strength when viewed from above on a membrane specimen (20 cm (width) x 30 cm (height)) according to one embodiment of the present invention.

[0030] Figure 5 shows a SEM image of the surface of the separation membrane of Comparative Example 1 of the present invention.

[0031] Figure 6 shows a SEM image of the surface of the separation membrane of Comparative Example 2 of the present invention.

[0032] Figure 7 shows an SEM image of the surface of the separation membrane of Example 1 of the present invention.

[0033] Figure 8 shows a SEM image of the surface of the separation membrane of Example 2 of the present invention.

[0034] Figure 9 shows a SEM image of the surface of the separation membrane of Example 3 of the present invention.

[0035] Figure 10 shows an SEM image of the surface of the separation membrane of Example 4 of the present invention.

[0036] 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.

[0037] In this specification, “A and / or B” means “A and B, or A or B.”

[0038] 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.

[0039] 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.

[0040] 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.

[0041] Hereinafter, an embodiment of the present invention will be described in detail with reference to the attached drawings. The drawings may be exaggerated, omitted, or schematically illustrated to explain or emphasize the contents of an embodiment of the present invention.

[0042] Hereinafter, the present invention will be described in more detail.

[0043] One embodiment of the present invention includes a separator (100) for an electrochemical device, including a porous polymer substrate (110); a coating layer (130) provided on at least one surface of the porous polymer substrate and including a first polymer binder and inorganic particles; and an adhesive layer (150) provided on the coating layer and including a second polymer binder and a plate-like silicate composition; wherein the plate-like silicate composition includes one selected from the group consisting of SiO2, MgO, Li2O, Na2O, and combinations thereof.

[0044] The electrochemical device separator (100) according to one embodiment of the present invention can prevent the components included in the adhesive layer (150) from being unevenly distributed during adhesive layer coating, thereby improving coating uniformity.

[0045] FIG. 1 is a schematic diagram of a separator for an electrochemical device according to one embodiment of the present invention. Referring to FIG. 1, a separator (100) for an electrochemical device according to one embodiment of the present invention will be described in detail.

[0046] 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 the porous polymer substrate (110), thereby allowing lithium ions to pass through while blocking electrical contact, and implementing a shutdown function at an appropriate temperature.

[0047] According to one embodiment of the present 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 separation membrane manufactured using such a polyolefin-based resin as a base resin, i.e., having a large number of pores, can provide a shutdown function at an appropriate temperature.

[0048] According to one embodiment of the present invention, the weight average molecular weight of the polyolefin resin may be 500,000 or more and 1,500,000 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 weights according to the content ratio of each polyolefin resin.

[0049] In this specification, 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.

[0050] - Column: PL Olexis (Polymer Laboratories)

[0051] - Solvent: TCB (Trichlorobenzene)

[0052] - Flow rate: 1.0 ml / min

[0053] - Sample concentration: 1.0 mg / ml

[0054] - Injection volume: 200 ㎕

[0055] - Column temperature: 160 ℃

[0056] - Detector: Agilent High Temperature RI detector

[0057] - Standard: Polystyrene (corrected with a cubic function)

[0058] According to one embodiment of the present invention, the porous polymer substrate (110) may be manufactured by a method (wet method) in which a polyolefin resin is mixed with a plasticizer at a high temperature to form a single phase, the polymer material and the plasticizer are phase-separated during a cooling process, the plasticizer is extracted to form pores, and then stretching and heat-setting are performed. In addition, the porous polymer substrate using the polyolefin resin may have a core portion made of a mixture of polyethylene and polypropylene and a polyethylene skin portion laminated on both sides of the core portion.

[0059] According to one embodiment of the present invention, the average size of the pores and the maximum size of the pores of the porous polymer substrate (110) can be easily manufactured by a person skilled in the art by controlling the mixing ratio of the plasticizer, the stretching ratio, the heat-setting treatment temperature, etc. to conform to the scope of the present invention.

[0060] According to one embodiment of the present invention, the thickness of the porous polymer substrate (110) may be 1 ㎛ or more and 50 ㎛ or less. Specifically, the thickness of the porous polymer substrate may be 2 ㎛ or more and 45 ㎛ or less, 3 ㎛ or more and 40 ㎛ or less, 4 ㎛ or more and 35 ㎛ or less, 5 ㎛ or more and 30 ㎛ or less, 6 ㎛ or more and 25 ㎛ or less, 7 ㎛ or more and 20 ㎛ or less, or 8 ㎛ or more and 15 ㎛ or less. By controlling the thickness of the porous polymer substrate within the above-described range, the energy density of the battery can be improved.

[0061] According to one embodiment of the present invention, the porosity of the porous polymer substrate (110) may be 10% by volume or more and 90% by volume or less. Specifically, the porosity of the porous polymer substrate may be 10% by volume or more and 90% by volume or less, 20% by volume or more and 80% by volume or less, 30% by volume or more and 70% by volume or less, or 40% by volume or more and 60% by volume or less. By controlling the porosity of the porous polymer substrate within the above-described range, the permeability of lithium ions through the separator can be controlled.

[0062] According to one embodiment of the present invention, the coating layer (130) is provided on at least one surface of the porous polymer substrate (110). As described above, the electrochemical device separator (100) includes the coating layer (130) provided on at least one surface of the porous polymer substrate (110), thereby improving the heat resistance of the separator, improving the mechanical properties, and preventing the separator from shrinking at high temperatures and causing an electrical short circuit in the electrode.

[0063] According to one embodiment of the present invention, the coating layer (130) includes a first polymer binder and inorganic particles. As described above, by including the first polymer binder and the inorganic particles, the coating layer improves the heat resistance of the separator, improves the mechanical properties, prevents the separator from shrinking at high temperatures and causing an electrical short circuit in the electrode, and can form pores within the coating layer.

[0064] According to one embodiment of the present invention, the coating layer (130) may be formed by inorganic particles being bound by first polymer binder particles and accumulated within the side. The pores within the coating layer may be derived from interstitial volume, which is an empty space between the inorganic particles.

[0065] According to one embodiment of the present invention, the coating layer (130) may include a plurality of pores. Specifically, the coating layer may be a porous coating layer. More specifically, the coating layer may be a porous coating layer including a plurality of pores therein. As described above, by including a plurality of pores, the coating layer can physically block the negative electrode and the positive electrode while allowing lithium ions to pass through and current to flow.

[0066] According to one embodiment of the present invention, the thickness of the coating layer (130) may be formed to a thickness of 1 ㎛ to 20 ㎛ on either side of the porous polymer substrate (110). Specifically, the thickness of the coating layer (130) may be 1 ㎛ to 10 ㎛, 1 ㎛ to 8 ㎛, 1 ㎛ to 6 ㎛, 1 ㎛ to 4 ㎛, or 1 ㎛ to 2 ㎛ on either side of the porous polymer substrate (110), and preferably 1.5 ㎛. By controlling the thickness of the coating layer (130) within the above-described range, the heat resistance or electrical resistance of the separator may be controlled within an appropriate range.

[0067] In one embodiment of the present invention, the thickness of the porous polymer substrate (110) and / or the coating layer (130) can be measured using a contact thickness measuring device. The contact thickness measuring device can be, for example, VL-50S-B from Mitutoyo.

[0068] According to one embodiment of the present invention, the first polymer binder may be an acrylic binder, a polyvinylidene binder, or a combination thereof. The combination of the acrylic binder and the polyvinylidene binder may be a mixture of the acrylic binder and the polyvinylidene binder, a copolymer including the acrylic repeating unit and the polyvinylidene repeating unit, or a hybrid of the acrylic binder and the polyvinylidene binder. In addition, the polyvinylidene binder may be a copolymer of polyvinylidene fluoride (PVdF) and hexafluoropropylene (HFP). By selecting the polymer binder particles as described above, the porosity of the separator can be maintained, and the adhesion between the electrode and the separator can be improved in the lamination process of the battery, so that the battery can be easily manufactured, and the stacking process can be stably implemented. Furthermore, the porosity of the separator can be maintained, and the adhesive strength can be maintained even when the coating layer is wetted by the electrolyte after battery activation. Furthermore, the stiffness of the battery can be improved, and banding of the separator can be prevented.

[0069] According to one embodiment of the present invention, the acrylic binder is a polymer containing a carboxylic acid ester as a repeating unit, and may preferably be a (meth)acrylic acid ester or an acrylic-styrene copolymer.

[0070] 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 may be at least one selected from these. Among these, at least one selected from methyl (meth)acrylate, ethyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate is preferable, and methyl (meth)acrylate is particularly preferable.

[0071] 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 the group consisting of styrene-butyl acrylate, styrene-butadiene rubber, nitrile-butadiene rubber, acrylonitrile-butadiene rubber, acrylonitrile-butadiene-styrene rubber, and acrylate polymers, and more specifically, may be a copolymer including acrylate.

[0072] According to one embodiment of the present invention, the average particle diameter (D50) of the first polymer binder particles is not particularly limited, but is preferably in the range of 0.1 ㎛ to 0.5 ㎛ in order to form a coating layer (130) with a uniform thickness and an appropriate porosity. Specifically, the average particle diameter (D50) of the first polymer binder particles may be 0.1 ㎛ to 0.4 ㎛, 0.1 ㎛ to 0.3 ㎛, or 0.1 ㎛ to 0.2 ㎛. By controlling the average particle diameter (D50) of the first polymer binder particles within the above-described range, the dispersibility in the slurry prepared for manufacturing the coating layer can be improved, and the thickness of the formed coating layer can be reduced.

[0073] According to one embodiment of the present invention, the polyvinylidene-based binder may be a polyvinylidene-based binder having a hexafluoropropylene (HFP) content of 1 wt% or more and 50 wt% or less. Specifically, the hexafluoropropylene (HFP) content in the polyvinylidene-based binder may be 1 wt% or more and 50 wt% or less, 2 wt% or more and 45 wt% or less, 3 wt% or more and 40 wt% or less, 4 wt% or more and 35 wt% or less, 5 wt% or more and 30 wt% or less, 7 wt% or more and 25 wt% or less, or 10 wt% or more and 20 wt% or less. As described above, by selecting the polyvinylidene-based binder as a polyvinylidene-based binder having a hexafluoropropylene content of 1 wt% or more and 50 wt% or less, the porosity of the separator can be maintained, and the adhesive strength can be maintained even when the coating layer is wetted by the electrolyte after battery activation. In the present specification, the degree of substitution of the polyvinylidene-based binder may mean the weight ratio containing hexafluoropropylene.

[0074] According to one embodiment of the present invention, the content of the first polymer binder may be 1 part by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the coating layer (130). Specifically, the content of the first polymer binder may be 1 part by weight or more and 9 parts by weight or less, 1 part by weight or more and 8 parts by weight or less, 1 part by weight or more and 7 parts by weight or less, 1 part by weight or more and 6 parts by weight or less, 1 part by weight or more and 5 parts by weight or less, 1 part by weight or more and 4 parts by weight or less, or 1 part by weight or more and 3 parts by weight or less with respect to 100 parts by weight of the coating layer (130). By controlling the content of the polymer binder particles within the above-described range, the ease of assembly can be improved in the process of assembling the electrode.

[0075] According to one embodiment of the present invention, when combining the acrylic binder and the polyvinylidene binder in the coating layer (130), the weight ratio may be 9:1 to 1:9. Specifically, when combining the acrylic binder and the polyvinylidene binder in the coating layer (130), the weight ratio may be 8:1 to 1:8, 7:1 to 1:7, 6:1 to 1:6, 5:1 to 1:5, 4:1 to 1:4, 3:1 to 1:3, or 2:1 to 1:2. By adjusting the weight ratio of the acrylic binder and the polyvinylidene binder within the above-described range, the wet adhesiveness and the dry adhesiveness of the separator for an electrochemical device can be simultaneously improved.

[0076] 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).

[0077] According to one embodiment of the present invention, non-limiting examples of the inorganic particles 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, 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.

[0078] According to one embodiment of the present invention, the average particle diameter (D50) of the inorganic particles is not particularly limited, but is preferably in the range of 0.1 ㎛ to 1 ㎛ in order to form a coating layer (130) with a uniform thickness and an appropriate porosity. Specifically, the average particle diameter (D50) of the inorganic particles may be 0.2 ㎛ to 0.9 ㎛, 0.3 ㎛ to 0.8 ㎛, 0.4 ㎛ to 0.7 ㎛, or 0.5 ㎛ to 0.6 ㎛. Specifically, when it is less than 0.1 ㎛, the dispersibility of the inorganic particles in the slurry prepared for manufacturing the coating layer may be reduced, and when it exceeds 1 ㎛, the thickness of the formed coating layer may increase.

[0079] 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. Specifically, 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 the particle size is measured to calculate the particle size distribution. By calculating the particle diameter at the point where it becomes 50% of the cumulative distribution of particle numbers according to particle size in the measuring device, the D50 particle size can be measured.

[0080] According to one embodiment of the present invention, the content of the inorganic particles may be 95 parts by weight or more and less than 100 parts by weight with respect to 100 parts by weight of the coating layer (130). Specifically, the content of the inorganic particles may be 95 parts by weight or more and 99 parts by weight or less or 96 parts by weight or more and 98 parts by weight or less with respect to 100 parts by weight of the coating layer (130). By controlling the content of the inorganic particles included in the coating layer (130) within the above-described range, the heat resistance of the separator can be improved, thereby ensuring the safety of the battery.

[0081] According to one embodiment of the present invention, the separator (100) for an electrochemical device includes an adhesive layer (150) provided on the coating layer (130). As described above, since the separator for an electrochemical device includes an adhesive layer provided on the coating layer, the adhesion between the electrode and the separator can be secured during the lamination process of the separator and the electrode.

[0082] According to one embodiment of the present invention, the adhesive layer (150) includes a second polymer binder and a plate-like silicate composition. As described above, by including the second polymer binder and the plate-like silicate composition, the adhesive layer can improve dispersibility and form an adhesive layer with a uniform surface.

[0083] According to one embodiment of the present invention, the second polymer binder may be in particle form. As described above, by selecting the second polymer binder in particle form, thermal shrinkage suppression and internal short circuit can be prevented.

[0084] According to one embodiment of the present invention, the second polymer binder may be a polyvinylidene-based binder. Specifically, the polyvinylidene-based binder may be a polyvinylidene fluoride (PVdF)-based binder. As described above, by selecting the polyvinylidene fluoride-based binder as the polyvinylidene-based binder, the resistance of the separator can be reduced.

[0085] 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.

[0086] According to one embodiment of the present invention, the polyvinylidene-based binder included in the second polymer binder may have a hexafluoropropylene content of 10 wt% or more. Specifically, the polyvinylidene-based binder included in the second polymer binder may have a hexafluoropropylene content of 10 wt% or more and 80 wt% or less, 15 wt% or more and 75 wt% or less, 20 wt% or more and 70 wt% or less, 25 wt% or more and 65 wt% or less, 30 wt% or more and 60 wt% or less, 35 wt% or more and 55 wt% or less, or 40 wt% or more and 50 wt% or less. By controlling the content of hexafluoropropylene included in the polyvinylidene-based binder in the second polymer binder within the above-described range, the resistance of the separator can be reduced. The content of the hexafluoropropylene (HFP) monomer 1 H-NMR and / or 19 It can be measured by F-NMR.

[0087] According to one embodiment of the present invention, the content of the second polymer binder may be 80 parts by weight or more and 90 parts by weight or less based on 100 parts by weight of the adhesive layer (150). Specifically, it may be 81 parts by weight or more and 89 parts by weight or less, 82 parts by weight or more and 88 parts by weight or less, or 85 parts by weight or more and 87 parts by weight or less. By controlling the content of the second polymer binder within the above-described range, the phase stability of the separator can be improved.

[0088] According to one embodiment of the present invention, the particle size (D50) of the second polymer binder may be 1 μm or more and 1.5 μm or less. By controlling the particle size (D50) of the second polymer binder within the above-described range, the thickness of the adhesive layer can be controlled.

[0089] According to one embodiment of the present invention, the adhesive layer may be provided so that a portion of the coating layer is exposed. Specifically, the adhesive layer may not be applied entirely over the coating layer, but may be applied partially.

[0090] According to one embodiment of the present invention, the adhesive layer may be distributed with a coverage corresponding to more than 86% and less than 99% of the surface area of ​​the coating layer. Specifically, the adhesive layer may be distributed with a coverage corresponding to more than 87% and less than 98%, more than 88% and less than 97%, more than 89% and less than 95%, or more than 90% and less than 94% of the surface area of ​​the coating layer. If it is less than the above-described range, the portion of the coating layer that is exposed increases, and accordingly, the coating uniformity deteriorates, and the deviation of the adhesive strength and peel strength of the separator depending on the measurement position increases, which may deteriorate the performance of the battery, and if it is more than the above-described range, the air permeability may deteriorate.

[0091] According to one embodiment of the present invention, the plate-like silicate composition includes one selected from the group consisting of SiO2, MgO, Li2O, Na2O, and combinations thereof. In the present specification, the plate-like silicate composition may mean that the silicate forms a plate-like structure. As described above, by the plate-like silicate composition including one selected from the group consisting of SiO2, MgO, Li2O, Na2O, and combinations thereof, phase stability can be improved and uniformity of the adhesive layer can be enhanced.

[0092] According to one embodiment of the present invention, the plate-like silicate composition may contain SiO2 in an amount of 50 wt% or more and 60 wt% or less. Specifically, the content of SiO2 in the plate-like silicate composition may be 51 wt% or more and 59 wt% or less, 52 wt% or more and 58 wt% or less, 53 wt% or more and 57 wt% or less, or 54 wt% or more and 56 wt% or less. By controlling the content of SiO2 within the above-described range, the dispersibility of the slurry for the adhesive layer can be improved and phase separation can be prevented.

[0093] According to one embodiment of the present invention, the plate-like silicate composition may contain MgO in an amount of 22 wt% or more and 28 wt% or less. Specifically, the content of MgO in the plate-like silicate composition may be 23 wt% or more and 27 wt% or less or 24 wt% or more and 26 wt% or less. By controlling the content of MgO within the above-described range, the dispersibility of the slurry for the adhesive layer can be improved and phase separation can be prevented.

[0094] According to one embodiment of the present invention, the plate-like silicate composition may contain Li2O in an amount of 0.5 wt% or more and 2.0 wt% or less. Specifically, the content of Li2O in the plate-like silicate composition may be 0.6 wt% or more and 1.9 wt% or less, 0.7 wt% or more and 1.8 wt% or less, 0.8 wt% or more and 1.7 wt% or less, 0.9 wt% or more and 1.6 wt% or less, 1.0 wt% or more and 1.5 wt% or less, 1.1 wt% or more and 1.4 wt% or less, or 1.2 wt% or more and 1.3 wt% or less. By controlling the content of Li2O within the above-described range, the dispersibility of the slurry for the adhesive layer can be improved and phase separation can be prevented.

[0095] According to one embodiment of the present invention, the plate-like silicate composition may contain Na2O in an amount of 2.0 wt% or more and 8.0 wt% or less. Specifically, the content of Na2O in the plate-like silicate composition may be 3.0 wt% or more and 7.0 wt% or less or 4.0 wt% or more and 6.0 wt% or less. By controlling the content of Na2O within the above-described range, the dispersibility of the slurry for the adhesive layer can be improved and phase separation can be prevented.

[0096] According to one embodiment of the present invention, the content of the plate-like silicate composition may be 0.1 part by weight or more and 1.0 part by weight or less with respect to 100 parts by weight of the slurry for the adhesive layer. Specifically, the content of the plate-like silicate composition may be 0.2 part by weight or more and 0.9 part by weight or less, 0.2 part by weight or more and 0.8 part by weight or less, 0.2 part by weight or more and 0.7 part by weight or less, or 0.3 part by weight or more and 0.6 part by weight or less with respect to 100 parts by weight of the slurry for the adhesive layer. By controlling the content of the plate-like silicate composition within the above-described range, the dispersibility of the slurry for the adhesive layer can be improved and phase separation can be prevented.

[0097] According to one embodiment of the present invention, the content of the plate-like silicate composition may be 1 part by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the adhesive layer. Specifically, the content of the plate-like silicate composition may be 1.5 parts by weight or more and 10 parts by weight or less, 1.5 parts by weight or more and 9 parts by weight or less, 1.5 parts by weight or more and 8 parts by weight or less, 1.5 parts by weight or more and 7 parts by weight or less, 1.5 parts by weight or more and 6 parts by weight or less, 2 parts by weight or more and 6 parts by weight or less, 2.5 parts by weight or more and 6 parts by weight or less, or 2.5 parts by weight or more and 5.5 parts by weight or less with respect to 100 parts by weight of the adhesive layer. By controlling the content of the plate-like silicate composition within the above-described range, the dispersibility of the slurry for the adhesive layer can be improved and phase separation can be prevented.

[0098] According to one embodiment of the present invention, the specific surface area of ​​the plate-shaped silicate composition is 250 m 2 / g or more than 400 m 2 / g or less. Specifically, the specific surface area of ​​the plate-shaped silicate composition is 260 m 2 / g or more than 390 m 2 / g or less, 270 m 2 / g or more than 380 m 2 / g or less, 280 m 2 / g or more than 370 m 2 / g or less, 290 m 2 / g or more than 360 m 2 / g or less, 300 m 2 / g or more than 350 m 2 / g or less, 310 m 2 / g or more than 340 m 2 / g or less or 20 m 2 / g or more than 330 m 2 / g or less. By controlling the specific surface area of ​​the plate-like silicate composition within the above-described range, the dispersibility of the plate-like silicate composition itself can be improved, thereby increasing the uniformity of the adhesive layer.

[0099] In this specification, "specific surface area" may be calculated using the Brunauer-Ennett-Teller model (BET) from the measured N2 adsorption isotherm when an adsorption isotherm is measured at -196 ℃ conditions up to 1 bar using a BET-specific surface area analyzer (BEL, Microtrac Co.).

[0100] According to one embodiment of the present invention, the density of the plate-shaped silicate composition is 900 kg / m 3 Up to 1050 kg / m 3 The density of the above plate-shaped silicate composition may be 910 kg / m 3 Up to 1040 kg / m 3 , 920 kg / m 3 Up to 1030 kg / m 3 , 930 kg / m 3 Up to 1020 kg / m 3 , 940 kg / m 3 Up to 1010 kg / m 3 , 950 kg / m 3 Up to 1000 kg / m 3 , 960 kg / m 3 Up to 990 kg / m 3 or 970 kg / m 3 Up to 980 kg / m 3 By controlling the density of the plate-shaped silicate composition within the above-described range, the weight of the adhesive layer can be reduced, and the energy density of the separator can be improved.

[0101] According to one embodiment of the present invention, the pH of the aqueous suspension containing 2 wt% or more and 5 wt% or less of the plate-like silicate composition may be 8.0 or more and 12.0 or less. Specifically, the pH of the aqueous suspension containing 2 wt% of the plate-like silicate composition may be 8.0 or more and 12.0 or less. In the present specification, the aqueous suspension may mean particles dispersed using water as a dispersion medium. The aqueous suspension containing 2 wt% of the plate-like silicate composition may mean particles dispersed by mixing and dispersing 98 wt% of water as a dispersion medium and 2 wt% of the plate-like silicate composition as particles. Specifically, the pH of the aqueous suspension containing 2 wt% of the plate-like silicate composition may be 8.5 or more and 10.5 or less, or 9.0 or more and 10.0 or less. By controlling the pH of the aqueous suspension containing 2 wt% of the plate-shaped silicate composition within the above-described range, the denaturation of the polymer binder particles contained in the slurry for the adhesive layer can be prevented.

[0102] According to one embodiment of the present invention, the plate-like silicate composition may further include P2O5, F, and a combination thereof. As described above, by the plate-like silicate composition further including P2O5, F, and a combination thereof, the uniformity of the adhesive layer can be improved, and the surface of the separator can be implemented uniformly.

[0103] According to one embodiment of the present invention, the plate-like silicate composition may be laponite. By selecting the plate-like silicate composition as laponite as described above, the uniformity of the adhesive layer can be improved, and the surface of the separator can be implemented uniformly.

[0104] According to one embodiment of the present invention, the thickness of the adhesive layer may be 0.5 μm or more and 1 μm or less. Preferably, the thickness of the adhesive layer may be 0.75 μm.

[0105] One embodiment of the present invention provides a method for manufacturing a separator for an electrochemical device, comprising the steps of: mixing a slurry for an adhesive layer (150) including a second polymer binder and a plate-shaped silicate composition; applying the slurry for the adhesive layer on at least one surface of a porous polymer substrate having a coating layer formed thereon; and drying the slurry for the adhesive layer to form an adhesive layer.

[0106] A method for manufacturing a separator for an electrochemical device according to one embodiment of the present invention can maintain adhesive strength during a lamination process with an electrode, and can maintain adhesive strength after battery activation to improve stiffness or prevent bending of a pouch-type cell. Furthermore, the insulating and thermal conductivity properties of the separator can be improved, and the uniformity of the adhesive layer can be improved. In addition, the dispersibility of particles dispersed within the slurry for the adhesive layer can be improved, thereby preventing phase separation even when stored or left for a long period of time.

[0107] According to one embodiment of the present invention, the method for manufacturing the electrochemical device separator (100) includes a step of mixing a slurry for an adhesive layer (150) including a second polymer binder and a plate-shaped silicate-based composition. By including the step of mixing a slurry for an adhesive layer (150) including a second polymer binder and a plate-shaped silicate-based composition as described above, an adhesive layer can be easily formed on the separator.

[0108] According to one embodiment of the present invention, a polymer binder emulsion may be prepared by dispersing second polymer binder particles in water, which is a suitable dispersion medium, to thereby prepare a slurry for an adhesive layer. As described above, by dispersing second polymer binder particles in water, which is a suitable dispersion medium, to thereby prepare a polymer binder emulsion, thereby preparing a slurry for an adhesive layer, contaminants generated during the manufacturing process can be minimized. In the present specification, the dispersion medium may refer to a solvent used in the process of preparing the slurry.

[0109] According to one embodiment of the present invention, the plate-like silicate composition may be added to the polymer binder emulsion. As described above, by adding the plate-like silicate composition to the polymer binder emulsion, the dispersibility of the particles can be improved, thereby preventing phase separation of the slurry for the adhesive layer and improving storage stability.

[0110] According to one embodiment of the present invention, the polymer binder emulsion may further include a dispersant. Specifically, the dispersant may be a polyacrylic dispersant. As described above, by further including a polyacrylic dispersant in the polymer binder emulsion, the degree of dispersion of particles dispersed within the polymer binder emulsion can be improved, and the uniformity of the adhesive layer can be improved.

[0111] According to one embodiment of the present invention, the content of the dispersant may be 1 part by weight or more and 5 parts by weight or less with respect to 100 parts by weight of the polymer binder emulsion. Preferably, it may be 2.5 parts by weight.

[0112] According to one embodiment of the present invention, the polymer binder emulsion may further comprise a surfactant. Specifically, the content of the surfactant may be 1 part by weight or more and 3 parts by weight or less, based on 100 parts by weight of the polymer binder emulsion. Preferably, the content is 0.5 parts by weight.

[0113] According to one embodiment of the present invention, the method for manufacturing the electrochemical device separator (100) includes a step of applying the slurry for the adhesive layer on at least one surface of a porous polymer substrate (110) on which a coating layer (130) is formed. By including the step of applying the slurry for the adhesive layer on at least one surface of the porous polymer substrate (110) as described above, the adhesive layer can be formed with a single application.

[0114] According to one embodiment of the present invention, the method for applying the slurry for the adhesive 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.

[0115] According to one embodiment of the present invention, the method for manufacturing the electrochemical device separator (100) includes a step of drying the slurry for the adhesive layer to form a coating layer (130). By including the step of drying the slurry for the adhesive layer to form a coating layer (130) as described above, damage to the adhesive layer can be minimized, and the dispersion medium included in the slurry can be easily removed.

[0116] One embodiment of the present invention includes an electrochemical device comprising: an anode; a cathode; and a separator interposed between the anode and the cathode.

[0117] An electrochemical device according to one embodiment of the present invention can improve the performance of a battery by improving the coating uniformity of an adhesive layer.

[0118] In one embodiment of the present invention, the 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 the present 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.

[0119] 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.

[0120] 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.

[0121] According to one embodiment of the present invention, the conductive material may be, for example, one selected from the group consisting of 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 among these. More specifically, the conductive material may be one selected from the group consisting of 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 among these.

[0122] 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.

[0123] 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.

[0124] According to one embodiment of 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. Specifically, it may be N-methylpyrrolidone (ADC-01, LG Chemical).

[0125] According to one embodiment of the present invention, the content of the dispersant included in the positive electrode slurry may be more than 0 part by weight and less than or equal to 0.5 part by weight with respect to 100 parts by weight of the positive electrode slurry. Specifically, the content of the dispersant included in the positive electrode slurry may be more than 0.05 part by weight and less than or equal to 0.4 part by weight with respect to 100 parts by weight of the positive electrode slurry.

[0126] According to one embodiment of the present invention, the negative electrode slurry for producing the negative electrode active material layer may include a dispersant, and the dispersant may be a polypyrrolidone-based compound. Specifically, the dispersant may be polyvinylpyrrolidone (Polyvinylpyrrolidone, Junsei, Japan).

[0127] According to one embodiment of the present invention, the content of the dispersant included in the cathode slurry may be more than 0 part by weight and less than or equal to 0.5 part by weight with respect to 100 parts by weight of the cathode slurry. Specifically, the content of the dispersant included in the cathode slurry may be more than 0.05 part by weight and less than or equal to 0.4 part by weight with respect to 100 parts by weight of the cathode slurry.

[0128] 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.

[0129] According to one embodiment of the present invention, the electrolyte is A + B - As a salt with the same structure, 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.

[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. Specific 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] Manufacturing of porous polymer substrates

[0135] Polyethylene resin (weight average molecular weight 900,000) was extruded and a porous polymer substrate (total thickness of approximately 9 ㎛, porosity of 40% by volume) was manufactured using a wet method.

[0136] Coating layer formation

[0137] Al2O3 powder with a D50 particle size of 600 nm was prepared as an inorganic particle. An acrylic emulsion (CSB-130, Toyo Ink Co., Ltd.) with a D50 particle size of 150 nm was prepared as the first binder polymer, and sodium carboxymethyl cellulose (CMC-Na) (SG-L02, GL Chem Co., Ltd.) was prepared as a dispersant.

[0138] The above-prepared inorganic particles, first binder polymer, and dispersant were added to water at a weight ratio of 97:2:1, and dispersed to prepare a slurry for a coating layer.

[0139] 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 1.5 μm.

[0140] Adhesive layer formation and separator manufacturing

[0141] A copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF-HFP) (KYNAR 2821, Arkema) with a D50 particle size of 5 to 10 μm as a second polymer binder, a dispersant (BASF, DISPEX ULTRA PX 4585), and a surfactant (BASF, Hydroplalat WE 3221) were added to water, stirred at a speed of 800 to 1000 rpm for 10 minutes, and then a milling (dispersing) device was used to prepare a polymer binder mixture with an average particle size D50 of 1 to 1.5 μm.

[0142] At this time, the weight parts of the second polymer binder: dispersant: surfactant were included as 97:2.5:0.5.

[0143] Separately, laponite (density: 1,000 kg / m) containing 59.5 wt% SiO2, 27.5 wt% MgO, 0.8 wt% Li2O, and 2.8 wt% Na2O (including loss on ignition) as a plate-like silicate composition 3 , specific surface area: 370 m 2 / g, pH (in a 2 wt% aqueous suspension) = 9.8) was added in small amounts to the dispersion medium water and a 2 wt% aqueous suspension was prepared at 1,500 rpm until it became transparent.

[0144] After filtering the above suspension through a filter having a 400 mesh size, 15 parts by weight of the above suspension was added to 100 parts by weight of the above polymer binder mixture, and the mixture was stirred at a speed of 800 rpm to 1,000 rpm for 10 minutes to prepare a slurry for an adhesive layer.

[0145] At this time, the content of the plate-shaped silicate composition is 0.3 parts by weight with respect to 100 parts by weight of the slurry for the adhesive layer.

[0146] The slurry for the adhesive layer was applied to both sides of the above-mentioned manufactured coating layer using a doctor blade by bar coating, and dried with wind at 50°C using a heat gun to form an adhesive layer of 0.75 μm thickness on each side, thereby manufacturing a separator having a total thickness of 13.5 μm.

[0147] At this time, the content of the plate-shaped silicate composition is 2.6 parts by weight for 100 parts by weight of the adhesive layer manufactured after drying.

[0148]

[0149] <Example 2>

[0150] In the above Example 1, laponite (density: 1,000 kg / m) containing 55.0 wt% of SiO2, 27.0 wt% of MgO, 1.4 wt% of Li2O, 3.8 wt% of Na2O, and 5.6 wt% of F (including loss on ignition) as a plate-like silicate composition 3 , specific surface area: 330 m 2 / g, pH (2 wt% aqueous suspension) = 9.4) was added in small amounts to the dispersion medium water and the slurry for the adhesive layer was prepared in the same manner as in Example 1 except that a 2 wt% aqueous suspension was used until it became transparent at 1,500 rpm.

[0151]

[0152] <Example 3>

[0153] In the above Example 1, a laponite (density: 950 kg / m) containing 50.2 wt% of SiO2, 22.2 wt% of MgO, 1.2 wt% of Li2O, 7.5 wt% of Na2O, 55.4 wt% of P2O, and 4.8 wt% of F (including loss on ignition) as a plate-like silicate composition 3 , specific surface area: 300 m 2 / g, pH (2 wt% aqueous suspension) = 10.0) was added in small amounts to the dispersion medium water and the slurry for the adhesive layer was prepared in the same manner as in Example 1 except that a 2 wt% aqueous suspension was used until it became transparent at 1,500 rpm.

[0154]

[0155] <Example 4>

[0156] In the above Example 1, a slurry for an adhesive layer was prepared in the same manner as in the above Example 1, except that 4 wt% of the aqueous suspension was used.

[0157] At this time, the content of the plate-shaped silicate composition is 0.6 parts by weight with respect to 100 parts by weight of the slurry for the adhesive layer, and the content of the plate-shaped silicate composition is 5.2 parts by weight with respect to 100 parts by weight of the adhesive layer manufactured after drying.

[0158]

[0159] <Comparative Example 1>

[0160] In the above Example 1, a separation membrane was manufactured in the same manner as in the above Example 1, except that a suspension containing a plate-shaped silicate composition was not used.

[0161]

[0162] <Comparative Example 2>

[0163] In the above Example 1, a slurry for the adhesive side was prepared in the same manner as in the above Example 1, except that 1 wt% of the aqueous suspension was used.

[0164] At this time, the content of the plate-shaped silicate composition is 0.15 parts by weight with respect to 100 parts by weight of the slurry for the adhesive layer, and the content of the plate-shaped silicate composition is 1.3 parts by weight with respect to 100 parts by weight of the adhesive layer manufactured after drying.

[0165]

[0166] <Manufacturing of electrochemical devices>

[0167] 1) Manufacturing of the anode

[0168] 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 positive electrode 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 positive electrode having a positive electrode active material layer (thickness 120 μm).

[0169] 2) Manufacturing of cathode

[0170] 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).

[0171] 3) Lamination process

[0172] An electrochemical device was obtained by interposing a separator of the embodiment between the manufactured cathode and anode and performing a lamination process. The lamination process was performed using a hot press at 70°C and 5.2 MPa for 10 seconds.

[0173]

[0174] <Experimental Example 1: Confirming whether phase separation occurs>

[0175] The adhesive layer slurry of Examples 1 to 3 and Comparative Example 1 was placed in a 250 ml container at room temperature (20°C to 25°C) and placed on a horizontal surface. The occurrence of phase separation (layer separation) over time was checked and summarized in Table 1 below.

[0176]

[0177] Whether separation occurs after 1 day after 3 days Example 1 None None Example 2 None None Example 3 None None Example 4 None None Comparative Example 1 None Occurrence Comparative Example 2 None Occurrence

[0178]

[0179] Figure 2 is a photograph showing whether phase separation occurred in the slurry for the adhesive layer of Comparative Example 1 (A) and Example 1 (B) of the present invention.

[0180] Figure 3 is a photograph showing whether phase separation occurred in the slurry for the adhesive layer of Comparative Example 1 (A), Example 2 (C), and Example 3 (D) of the present invention.

[0181] Referring to Table 1 above, it was confirmed that Examples 1 to 4 including the plate-shaped silicate composition did not cause phase separation within the slurry even after time elapsed after the slurry was prepared.

[0182] In contrast, Comparative Example 1, which did not include the plate-shaped silicate composition, confirmed that phase separation occurred within the slurry when left for 3 days.

[0183] Furthermore, it was confirmed that Comparative Example 2, which had a low content of the plate-shaped silicate composition, caused phase separation within the slurry when left for 3 days.

[0184]

[0185] <Experimental Example 2: Measurement of Membrane-Cathode Adhesion>

[0186] The separators of Examples 1 to 4 and Comparative Examples 1 and 2 were cut into 20 cm (width) x 30 cm (height), and the prepared electrodes and separators were laminated using a press under the conditions of 60°C, 6.5 MPa, and 1 second to produce specimens. The prepared specimens were fixed by attaching them to a glass plate using double-sided tape, and at this time, the electrodes were positioned so that they faced the glass plate. The separator portion of the specimens was peeled at an angle of 180° at a speed of 150 mm / min at 25°C, and the strength of the cathode at this time was measured, which is summarized in Table 2 below.

[0187] At this time, the adhesive strength was measured at each location with reference to Figure 4.

[0188]

[0189] Membrane-negative adhesion (gf / mm) measurement location 12345 Comparative example 11714131813 Comparative example 21417181315 Example 11615161516 Example 21516151515 Example 31515161515 Example 41413141415

[0190]

[0191] Referring to Table 2 above, it was confirmed that Examples 1 to 4 including the plate-shaped silicate composition achieved a level of adhesive strength similar to that of Comparative Example 1 even when including the plate-shaped silicate composition, and further, it was confirmed that the adhesive strength deviation according to the measurement position was smaller than that of Comparative Examples 1 and 2, thereby maintaining a uniform adhesive strength.

[0192] Specifically, in the case of Comparative Examples 1 and 2, the adhesive strength deviation occurred up to 5 gf / mm, and in the case of Examples 1 to 4, the adhesive strength deviation was up to 2 gf / mm.

[0193]

[0194] <Experimental Example 3: Peeling Strength Measurement>

[0195] The membranes of Examples 1 to 4 and Comparative Examples 1 and 2 were prepared as specimens with a size of 20 cm (width) x 30 cm (height), and an adhesive layer and a slide glass were attached to the specimens. Then, the specimens were pulled at 180° at a measurement speed of 300 mm / min using a UTM device (LLOYD Instrument LF Plus) and the results were summarized in Table 3 below.

[0196] At this time, the peel strength was measured at each location with reference to Figure 3.

[0197]

[0198] Peel strength (gf / mm) Measurement location 12345 Comparative example 11816201816 Comparative example 21816211816 Exemplary example 12625262526 Exemplary example 22424252425 Exemplary example 32526252525 Exemplary example 42827272826

[0199]

[0200] Referring to Table 3 above, Examples 1 to 4 including the plate-like silicate composition showed increased peel strength due to increased internal cohesion within the adhesive layer by including the plate-like silicate composition. In contrast, Comparative Example 1 showed a reduced peel strength because the slurry did not include the plate-like silicate composition, and Comparative Example 1 showed a somewhat reduced peel strength because the slurry contained a small amount of the plate-like silicate composition.

[0201] Furthermore, it was confirmed that Examples 1 to 4 maintained a uniform peel strength with less deviation in peel strength depending on the measurement position compared to Comparative Examples 1 and 2.

[0202] Specifically, in the case of Comparative Examples 1 and 2, the peel strength deviation occurred up to 5 gf / mm, and in the case of Examples 1 to 4, the adhesive strength deviation was up to 2 gf / mm.

[0203]

[0204] <Experimental Example 4: SEM observation and coverage measurement of the membrane surface>

[0205] Figure 5 shows a SEM image of the surface of the separation membrane of Comparative Example 1 of the present invention.

[0206] Figure 6 shows a SEM image of the surface of the separation membrane of Comparative Example 2 of the present invention.

[0207] Figure 7 shows an SEM image of the surface of the separation membrane of Example 1 of the present invention.

[0208] Figure 8 shows a SEM image of the surface of the separation membrane of Example 2 of the present invention.

[0209] Figure 9 shows a SEM image of the surface of the separation membrane of Example 3 of the present invention.

[0210] Figure 10 shows an SEM image of the surface of the separation membrane of Example 4 of the present invention.

[0211] Furthermore, the SEM image was analyzed using the IAM (Image Analysis Management) program to quantitatively quantify the coverage, which is shown in Table 4 below.

[0212]

[0213] Comparative Example 1 Comparative Example 2 Example 1 Example 2 Example 3 Example 4 Coverage of adhesive layer (%) 868792929393

[0214]

[0215] Referring to the above Figures 5 and 6, it can be seen that the surfaces of the membranes of Comparative Examples 1 and 2 have many areas where the coating layer containing inorganic substances is exposed between the adhesive layers due to the uneven coating of the adhesive layer caused by the agglomeration of binder particles.

[0216] Specifically, it can be seen that Comparative Example 1 has poor dispersibility because it does not include a plate-like silicate composition. Furthermore, it can be seen that Comparative Example 2 has insufficient dispersion stability because the aqueous suspension concentration of the plate-like silicate composition is reduced.

[0217] In contrast, referring to FIGS. 7 to 10, it can be seen that the surfaces of the membranes of Examples 1 to 3 are coated with an adhesive layer relatively uniformly compared to Comparative Examples 1 and 2.

[0218] Furthermore, according to Table 4 above, it can be confirmed that the coverage of the adhesive layer is improved in Examples 1 to 4 compared to Comparative Examples 1 and 2.

[0219] Accordingly, the separator for an electrochemical device according to one embodiment of the present invention includes a plate-shaped silicate composition in the adhesive layer, thereby maintaining the properties of a conventional separator while preventing phase separation of a slurry, thereby improving storage stability, improving the deviation of adhesive strength and peel strength by location, and further improving the peel strength of the adhesive layer.

[0220] [Explanation of symbols]

[0221] 100: Separator for electrochemical devices

[0222] 110: Porous polymer substrate

[0223] 130: Coating layer

[0224] 150: Adhesive layer

Claims

1. Porous polymer substrate; A coating layer provided on at least one surface of the porous polymer substrate, the coating layer including a first polymer binder and inorganic particles; and An adhesive layer provided on the above coating layer and including a second polymer binder and a plate-shaped silicate composition; A separator for an electrochemical device, wherein the plate-shaped silicate composition comprises one selected from the group consisting of SiO2, MgO, Li2O, Na2O, and combinations thereof.

2. In claim 1, A separator for an electrochemical device, wherein the adhesive layer is provided such that a portion of the coating layer is exposed.

3. In claim 1, A separator for an electrochemical device, wherein the coverage (%) of the above adhesive layer is 90% or more.

4. In claim 1, A separator for an electrochemical device, wherein the above plate-shaped silicate composition contains SiO2 in an amount of 50 wt% or more and 60 wt% or less.

5. In claim 1, A separator for an electrochemical device, wherein the above plate-shaped silicate composition contains MgO in an amount of 22 wt% or more and 28 wt% or less.

6. In claim 1, A separator for an electrochemical device, wherein the above plate-shaped silicate composition contains Li2O in an amount of 0.5 wt% or more and 2.0 wt% or less.

7. In claim 1, A separator for an electrochemical device, wherein the above plate-shaped silicate composition contains Na2O in an amount of 2.0 wt% or more and 8.0 wt% or less.

8. In claim 1, A separator for an electrochemical device, wherein the content of the plate-shaped silicate composition is 1 part by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the adhesive layer.

9. In claim 1, A separator for an electrochemical device, wherein the above plate-shaped silicate composition further comprises P2O5, F, and a combination thereof.

10. In claim 1, A separator for an electrochemical device, wherein the pH of the aqueous suspension containing the above-mentioned plate-shaped silicate composition in an amount of 2 wt% or more and 5 wt% or less is 8.0 or more and 12.0 or less.

11. In claim 1, A separator for an electrochemical device, wherein the above plate-shaped silicate composition is laponite.

12. In claim 1, Prepare a sample of the above membrane (20 cm (width) x 30 cm (height)), A separator for an electrochemical device, wherein when a force is applied at a 180° angle at a measurement speed of 300 mm / min using a UTM device (LLOYD Instrument LF Plus), the deviation of the peel strength measured at five arbitrary measurement locations within the specimen is 3 gf / mm or less.

13. An electrochemical device comprising: a positive electrode; a negative electrode; and a separator interposed between the positive electrode and the negative electrode, the separator of claim 1.

14. In claim 13, Prepare a sample of the above membrane (20 cm (width) x 30 cm (height)), An electrochemical device, wherein when the separator portion of the above specimen is peeled at an angle of 180° at a speed of 150 mm / min at 25°C, the deviation in the adhesive strength between the separator and the negative electrode measured at five arbitrary measurement locations within the specimen is 4 gf / mm or less.

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