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, the separator having, on a porous polymer substrate, a coating layer that includes inorganic particles, and allowing the grain size of a metal oxide in the inorganic particles to be adjusted so as to reduce the gas generated during driving of the electrochemical device, and thus the explosion safety of the electrochemical device can be improved.

Description

Separator for electrochemical devices and electrochemical devices containing the same

[0001] The present invention claims the benefit of Korean Patent Application No. 10-2024-0104225 filed with the Korean Intellectual Property Office on August 5, 2024, the entire contents of which are incorporated herein by reference. The present invention relates to a separator for an electrochemical device and an electrochemical device comprising the same, and more particularly, to a separator for an electrochemical device and an electrochemical device comprising the same, wherein a coating layer provided on a porous polymer substrate includes inorganic particles, and by controlling the crystal grain size of a metal oxide within the inorganic particles, gas generated during the operation of the electrochemical device is reduced, thereby improving the explosion safety of the electrochemical device.

[0002] 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.

[0003] Accordingly, various methods have been attempted to enhance the physical properties of membranes by adding a coating layer to a porous polymer substrate and by adding various substances to the coating layer to change the properties of the coating layer. For example, inorganic substances may be added to the coating layer to enhance the mechanical strength of the membrane, or inorganic substances or hydrates may be added to the coating layer to enhance the flame retardancy and heat resistance of the polymer substrate.

[0004] The separator can be bonded to the electrode through a lamination process, and a binder resin can be added to the slurry for the coating layer of the separator to secure adhesion between the electrode and the separator.

[0005] Meanwhile, moisture contained in electrochemical devices has the potential to react with the electrolyte, generating large amounts of gas. Gas generated at room or high temperatures during assembly and / or operation of electrochemical devices increases their resistance, reduces output and capacity retention, and degrades their performance. Furthermore, it increases the risk of explosion due to expansion of the device.

[0006] Therefore, there is a need to develop a technology that can reduce the amount of gas generated during the assembly and / or operation of electrochemical devices.

[0007] The technical problem to be achieved by the present invention is to provide a separator for an electrochemical device capable of reducing gas generated during assembly and / or operation of the electrochemical device, and an electrochemical device including the same.

[0008] 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.

[0009] One embodiment of the present invention provides a separator for an electrochemical device, comprising: a porous polymer substrate; and a coating layer provided on at least one surface of the porous polymer, the coating layer including inorganic particles and a first polymer binder; wherein the crystal grain size of the inorganic particles is 2 ㎛ or less.

[0010] According to one embodiment of the present invention, the average particle diameter of the inorganic particles may be 0.1 um or more and 10.0 um or less.

[0011] According to one embodiment of the present invention, the dielectric constant of the inorganic particles may be 10 or more.

[0012] According to one embodiment of the present invention, the inorganic particles may include a metal oxide represented by the following chemical formula 1.

[0013] [Chemical Formula 1]

[0014] A xB B y O z

[0015] The above A is one selected from the group consisting of Ba, Sr, Pb, Bi, Nai, K, Ca, Y, Gd, La, Li or these, the above B is one selected from the group consisting of Ti, Zr, Fe, Nb, Mn, Nb, Ta or these, and the above 0 < x ≤ 5, 0 < y ≤ 5 and 0 < z ≤ 5.

[0016] According to one embodiment of the present invention, the content of the inorganic particles may be 70 parts by weight or more with respect to 100 parts by weight of the coating layer.

[0017] According to one embodiment of the present invention, the first polymer binder may be an acrylic resin.

[0018] According to one embodiment of the present invention, an adhesive layer including a second polymer binder may be further included on at least a portion of the coating layer.

[0019] According to one embodiment of the present invention, the second polymer binder may be in particle form.

[0020] One embodiment of the present invention provides an electrochemical device including: an anode; a cathode; and a separator interposed between the anode and the cathode.

[0021] According to one embodiment of the present invention, the amount of gas generated after heating at 130°C for 1 hour may be 7,000 μL or less.

[0022] A separator for an electrochemical device according to one embodiment of the present invention can reduce gas generation when assembling an electrochemical device at a high temperature.

[0023] A separator for an electrochemical device according to one embodiment of the present invention can improve the ionic conductivity of an electrolyte solution of an electrochemical device.

[0024] A separator for an electrochemical device according to one embodiment of the present invention can increase the dielectric constant of inorganic particles.

[0025] An electrochemical device according to one embodiment of the present invention can improve the lifespan and enhance explosion safety by preventing explosion due to gas generation.

[0026] Figure 1 is a schematic diagram of a separator for an electrochemical device according to one embodiment of the present invention. Specifically, Figure 1(a) is a separator for an electrochemical device having a coating layer on one surface of a polymer porous substrate, and Figure 1(b) is a separator for an electrochemical device having a coating layer on both surfaces of a polymer porous substrate.

[0027] Figure 2 is a schematic diagram illustrating inorganic particles, crystal grains and crystals.

[0028] Figure 3 is a schematic diagram of a separator for an electrochemical device according to one embodiment of the present invention. Specifically, Figure 3(a) is a separator for an electrochemical device having a coating layer and an adhesive layer on one surface of a polymer porous substrate, and Figure 3(b) is a separator for an electrochemical device having a coating layer and an adhesive layer on both surfaces of a polymer porous substrate.

[0029] Figure 4 is a schematic diagram of a separator for an electrochemical device according to one embodiment of the present invention. Specifically, Figure 4(a) is a separator for an electrochemical device having an adhesive layer including a second polymer binder in the form of a coating layer particle on one side of a polymer porous substrate, and Figure 4(b) is a separator for an electrochemical device having a coating layer and an adhesive layer on both sides of a polymer porous substrate.

[0030] Figure 5 is a schematic diagram of an electrochemical device according to one embodiment of the present invention.

[0031] Hereinafter, various embodiments of the present invention will be described in detail to enable those skilled in the art to easily practice the present invention. However, these examples are provided for illustrative purposes only, and the scope of the present invention is not limited by the following description.

[0032] Unless otherwise specified, the detailed description defining or specifying embodiments applies to all inventions and is not limited to the description of specific inventions. That is, the present disclosure also refers to combinations of separately disclosed embodiments. Additionally, unless otherwise specified, the singular forms "a," "an," and "the" include plural forms throughout the detailed description and the appended claims.

[0033] In this specification, when a part is said to "include" a component, this does not mean that other components are excluded, but rather that other components may be included, unless otherwise specifically stated. However, unless explicitly stated otherwise, "consists of" or "includes" may include "consists essentially of" and "consists of."

[0034] As used herein, the term "essentially comprising" may mean "comprising at least 70%," preferably "comprising at least 80%," and most preferably "comprising at least 90%." When referring to the amount of a component in a mixture of substances, the % is a weight percent based on the total weight of each mixture. For example, a substance essentially comprising polyethylene comprises polyethylene in an amount of at least 70% by weight based on the total weight of the substance.

[0035] In this specification, “A and / or B” means “A and B, or A or B.”

[0036] As used herein, when a component is referred to as "on" another component, unless otherwise specifically stated, this does not exclude other components from being placed between them, but rather means that other components may be placed thereon. However, unless explicitly stated otherwise, "on" also encompasses the meaning of "directly on," i.e., a situation where no other components can be placed thereon.

[0037] In this specification, the term "having pores" or "porous" 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.

[0038] 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.

[0039] The drawings attached to this specification illustrate preferred embodiments of the invention and, together with the description of the invention, serve to explain the principles of the invention, but are not intended to limit the scope of the invention. Furthermore, the shape, size, scale, or ratio of elements in the drawings included in this specification may be exaggerated for clarity.

[0040] Hereinafter, the present invention will be described in more detail.

[0041] One embodiment of the present invention provides a separator for an electrochemical device, comprising: a porous polymer substrate; and a coating layer provided on at least one surface of the porous polymer, the coating layer including inorganic particles and a first polymer binder; wherein the crystal grain size of the inorganic particles is 2 ㎛ or less.

[0042] A separator for an electrochemical device according to one embodiment of the present invention can reduce gas generation when assembling an electrochemical device at high temperatures. Furthermore, a separator for an electrochemical device according to one embodiment of the present invention can improve the ionic conductivity of the electrolyte of the electrochemical device. Furthermore, a separator for an electrochemical device according to one embodiment of the present invention can increase the dielectric constant of inorganic particles.

[0043] Figure 1 is a schematic diagram of a separator according to one embodiment of the present invention. Referring to Figure 1, a separator for an electrochemical device according to one embodiment of the present invention will be described in detail.

[0044] According to one embodiment of the present invention, the electrochemical device separator (100) includes a porous polymer substrate. As described above, the electrochemical device separator (100) includes a porous polymer substrate (110), thereby allowing lithium ions to pass through while blocking electrical contact, and implementing a shutdown function at an appropriate temperature.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] - Column: PL Olexis (Polymer Laboratories)

[0049] - Solvent: TCB (Trichlorobenzene)

[0050] - Flow rate: 1.0 ml / min

[0051] - Sample concentration: 1.0 mg / ml

[0052] - Injection volume: 200 ㎕

[0053] - Column temperature: 160 ℃

[0054] - Detector: Agilent High Temperature RI detector

[0055] - Standard: Polystyrene (corrected with a cubic function)

[0056] 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.

[0057] According to one embodiment of the present invention, the average size of the pores and the maximum size of the pores of the separation membrane (100) 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.

[0058] According to one embodiment of the present invention, the thickness of the porous polymer substrate 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.

[0059] In one embodiment of the present invention, the thickness of the porous polymer substrate and / or the coating layer, etc., can be measured using a contact-type thickness measuring device. The contact-type thickness measuring device can be, for example, VL-50S-B from Mitutoyo.

[0060] According to one embodiment of the present invention, the porosity of the porous polymer substrate 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.

[0061] In this specification, “porosity” means the ratio of the volume occupied by pores to the total volume, and uses volume% as its unit, and can be used interchangeably with terms such as porosity and porosity.

[0062] In this specification, porosity may correspond to a value obtained by subtracting a volume converted to the weight and density of each component of the porous polymer substrate (110) and / or coating layer (130) from the volume calculated in the thickness, width, and length of the porous polymer substrate (110) and / or coating layer (130).

[0063] In one embodiment of the present invention, the porosity and pore size of the porous polymer substrate (110) and / or the coating layer (130) can be measured by the BET 6-point method using a scanning electron microscope (SEM) image, a mercury porosimeter, a capillary flow porometer (iCFP-1100 by poretech), or a porosimetry analyzer (Bell Japan Inc, Belsorp-II mini) by a nitrogen gas adsorption flow method. At this time, it may be advantageous to use a capillary flow porometer, which can be measured in accordance with ASTM-F316.

[0064] According to one embodiment of the present invention, the surface of the coating layer may have pores uniformly distributed. The uniform distribution can realize a constant pore size and shape over the entire surface when an electronic image of 60 μm X 60 μm is taken as measured by SEM. The pore size on the surface of the coating layer is in the range of 0.001 μm to 30 μm, or 30 μm or less, 25 μm or less, 25 μm or less, 20 μm or less, 15 μm or less, 10 μm or less, 5 μm or less, 3 μm or less, or 2 μm or less, and may be 0.001 μm or more, 0.01 μm or more. The pore size of the surface of the coating layer may be measured by SEM by taking an electronic image of 60 μm X 60 μm. Alternatively, the pore size may be measured as known to those skilled in the art as described above. A uniform distribution can be represented by a regular pattern or spacing of pores across the surface when an electron image of 60 μm X 60 μm is taken as measured by SEM.

[0065] According to one embodiment of the present invention, the separator for an electrochemical device includes a coating layer provided on at least one surface of the porous polymer. FIG. 1(a) is a separator having a coating layer provided on one surface of a polymer porous substrate, and FIG. 1(b) is a separator having a coating layer provided on both surfaces of a polymer porous substrate. Specifically, as shown in FIG. 1, the separator (100) for an electrochemical device includes a coating layer (130) provided on one or both surfaces of the porous polymer substrate (110). As described above, since the separator (100) for an electrochemical device includes a coating layer (130) provided on at least one surface of the porous polymer substrate (110), the heat resistance of the separator can be improved, the mechanical properties can be improved, and the shrinkage of the separator at high temperatures can be prevented, thereby preventing an electrical short circuit of the electrode.

[0066] According to one embodiment of the present invention, the coating layer includes inorganic particles and a first polymer binder. As described above, by including the inorganic particles and the first polymer binder, the porosity of the coating layer can be improved, while reducing gas generated during assembly and operation of the electrochemical device.

[0067] 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.

[0068] According to one embodiment of the present invention, the coating layer (130) may be formed by the inorganic particles being bound by the first polymer binder particles and being integrated within the coating layer. The pores within the coating layer (130) may be derived from the interstitial volume, which is the empty space between the inorganic particles.

[0069] According to one embodiment of the present invention, the thickness of the coating layer (130) may be formed to a thickness of 1 μm to 20 μm on either side of the porous polymer substrate (110), but is not particularly limited thereto. The thickness of the coating layer can be adjusted to an appropriate range by those skilled in the art in terms of heat resistance or electrical resistance.

[0070] According to one embodiment of the present invention, the crystal grain size of the inorganic particles is 2 ㎛ or less. Specifically, the crystal grain size of the inorganic particles may be greater than 0 ㎛, 0.005 ㎛ or more, 0.01 ㎛ or more, 0.05 ㎛ or more, 0.1 ㎛ or more, 0.25 ㎛ or more, 0.5 ㎛ or more, 0.7 ㎛ or more, 0.8 ㎛ or more, 1.1 ㎛ or more, or 1.2 ㎛ or more, and may be 1.5 ㎛ or less, 1.2 ㎛ or less, 0.9 ㎛ or less, 0.8 ㎛ or less, 0.6 ㎛ or less, 0.5 ㎛ or less, 0.2 ㎛ or less, 0.1 ㎛ or less, 0.02 ㎛ or less, or 0.01 ㎛ or less. By controlling the crystal grain size of the inorganic particles within the above-described range, the dielectric constant can be increased and the gas generated during assembly and / or operation of the electrochemical device can be reduced.

[0071] In this specification, the grain size may mean something different from the grain size of an inorganic particle and the crystal grain size. Fig. 2 is a schematic diagram illustrating an inorganic particle, a grain, and a crystal. Referring to Fig. 2, a grain may mean a crystal region having the same crystal orientation. That is, an inorganic particle may be composed of the grains. The grain size refers to the size of the grain, and may mean something different from the grain size of an inorganic particle and the crystal grain size.

[0072] In the present specification, the 'crystal grain size' may be measured by analyzing XRD data obtained by X-ray diffraction analysis of inorganic particles, which are the target powder, using the Rietveld refinement method. At this time, the X-ray diffraction analysis may be performed using a Bruker D8 Endeavor (light source: Cu-Kα, λ = 1.54 Å) equipped with a LynxEye XE-T-position sensitive detector, by placing a sample in a groove of a general powder holder, smoothing the surface of the sample using a slide glass, filling the sample so that the height of the sample matches the edge of the holder, and then measuring under the conditions of a step size = 0.016°, and a total scan time = approximately 1 / 20 minute for an FDS 0.5°, 2θ = 10° to 90° region. Specifically, instrumental broadening during grain size analysis can utilize the Fundamental Parameter Approach (FPA) implemented in the Bruker TOPAS program, and the entire peak range can be used for fitting. The peak shape can be fitted using only the Lorenzian contribution as the First Principle (FP) among the peak types available in TOPAS.

[0073] According to one embodiment of the present invention, the average particle diameter (D) of the inorganic particles 50 ) has no special limitations, but in order to form a coating layer (130) of uniform thickness and an appropriate porosity, it is preferably in the range of 0.1 ㎛ to 10 ㎛. Specifically, the average particle diameter (D) of the inorganic particles 50) may be 0.5 ㎛ or more and 9.0 ㎛ or less, 1.0 ㎛ or more and 8.0 ㎛ or less, 2.0 ㎛ or more and 7.0 ㎛ or less, or 3.0 ㎛ or more and 6.0 ㎛ or less. In the above-described range, the average particle diameter (D of the inorganic particles 50 ) can be controlled to prevent the dispersibility of inorganic particles from deteriorating in the slurry prepared for manufacturing a coating layer, and to reduce the thickness of the formed coating layer.

[0074] According to one embodiment of the present invention, the dielectric constant of the inorganic particles may be 10 or more. Specifically, the dielectric constant of the inorganic particles may be 50 or more and 5,500 or less, 60 or more and 5,300 or less, 400 or more and 4,500 or less, 500 or more and 4,100 or less, 1,300 or more and 2,500 or less, or 1,500 or more and 2,300 or less. By controlling the dielectric constant of the inorganic particles within the above-described range, the ionic conductivity of the electrolyte can be improved, and gas generated during assembly and / or operation of the electrochemical device can be reduced.

[0075] In this specification, the dielectric constant may be measured using the ASTM D 150 standard test method. Specifically, the dielectric constant may be measured using the following method. A sample is manufactured by forming a pellet having a diameter of 100 mm and a thickness of 4 mm using high-pressure compression molding, and the dielectric constant is measured using the sample using the ASTM D 150 standard test method.

[0076] According to one embodiment of the present invention, the inorganic particles may include a metal oxide represented by the following chemical formula 1.

[0077] [Chemical Formula 1]

[0078] A x B y O z

[0079] The above A is one selected from the group consisting of Ba, Sr, Pb, Bi, Nai, K, Ca, Y, Gd, La, Li or these, the above B is one selected from the group consisting of Ti, Zr, Fe, Nb, Mn, Nb, Ta or these, and 0 < x ≤ 5, 0 < y ≤ 5 and 0 < z ≤ 5. Specifically, the above A may be Ba, Sr, Pb, Bi, Na / Bi, K / Na, Ca, Y, Gd, La or Li, and the above B may be Ti, Zr / Ti, Fe, Nb, Mn, Nb or Ta. More specifically, the above metal oxide may be LiNdO3, SrTiO3 or BaTiO3. By selecting the above metal oxide as described above, the permittivity can be implemented high, and the gas generated during assembly and / or operation of the electrochemical device can be reduced.

[0080] According to one embodiment of the present invention, the coating layer may further include other inorganic particles in addition to the inorganic particles containing the metal oxide. As described above, by the coating layer further including separate inorganic particles, the heat resistance of the separator can be improved, the mechanical properties can be improved, the shrinkage of the separator at high temperatures can be prevented, and an electrical short circuit of the electrode can be prevented, and pores can be formed within the coating layer.

[0081] According to one embodiment of the present invention, the inorganic particles additionally included in the coating layer (130) are not particularly limited as long as they are electrochemically stable. That is, in addition to the inorganic particles containing the metal oxide that can be used in one embodiment of the present invention, other inorganic particles can be used as long as they are within the operating voltage range of the applied electrochemical device (e.g., Li / Li). + There are no particular limitations as long as no oxidation and / or reduction reaction occurs at a voltage of 0 V to 5 V (as a reference).

[0082] According to one embodiment of the present invention, in addition to the inorganic particles containing the metal oxide, other inorganic particles include 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), 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.

[0083] In this specification, "D 50 "Particle size" means the particle size at the 50% point of the cumulative distribution of the number of particles according to the 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 the particle size distribution is calculated by measuring the difference in the diffraction pattern according to the particle size when the particles pass through the laser beam. By calculating the particle diameter at the point where it becomes 50% of the cumulative distribution of the number of particles according to the particle size in the measuring device, D 50 The diameter can be measured. The above "D 50 The "particle size" may be measured according to ISO 13320-1 (Particle size analysis - Laser diffraction methods).

[0084] According to one embodiment of the present invention, the content of the inorganic particles may be 70 parts by weight or more with respect to 100 parts by weight of the coating layer. Specifically, the content of the inorganic particles may be more than 70 parts by weight and less than 100 parts by weight, 72 parts by weight or more and 99 parts by weight or less, 74 parts by weight or more and 98 parts by weight or less, 76 parts by weight or more and 97 parts by weight or less, 78 parts by weight or more and 96 parts by weight or less, 80 parts by weight or more and 95 parts by weight or less, 81 parts by weight or more and 94 parts by weight or less, 82 parts by weight or more and 93 parts by weight or less, 83 parts by weight or more and 92 parts by weight or less, 84 parts by weight or more and 91 parts by weight or less, 85 parts by weight or more and 90 parts by weight or less, 86 parts by weight or more and 89 parts by weight or less, or 87 parts by weight or more and 88 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 (135) within the above-described range, the heat resistance of the separation membrane can be improved.

[0085] According to one embodiment of the present invention, the first polymer binder may be an acrylic resin. As described above, by selecting the material of the first polymer binder particles as an acrylic resin, the porosity of the separator can be maintained, and the adhesive strength between the electrode and the separator can be improved during the lamination process of the battery, thereby facilitating the manufacture of the battery and stably implementing the stacking process.

[0086] According to one embodiment of the present invention, the acrylic resin 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.

[0087] According to one embodiment of the present invention, specific examples of the (meth)acrylic acid ester include 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.

[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 acrylic binder may be at least one selected from the group consisting of styrenebutadiene rubber, nitrile-butadiene rubber, acrylonitrile-butadiene rubber, acrylonitrile-butadiene-styrene rubber, and acrylate polymers, and more specifically, may be a copolymer including acrylate.

[0089] According to one embodiment of the present invention, the glass transition temperature (Tg) of the first polymer binder may be 20° C. or more and 60° C. or less. Specifically, the glass transition temperature (Tg) of the first polymer binder may be 22° C. or more and 58° C. or less, 24° C. or more and 56° C. or less, 26° C. or more and 54° C. or less, 28° C. or more and 52° C. or less, 30° C. or more and 50° C. or less, 32° C. or more and 48° C. or less, 34° C. or more and 46° C. or less, 36° C. or more and 44° C. or less, or 38° C. or more and 42° C. By controlling the glass transition temperature (Tg) of the first polymer binder within the above-described range, the viscosity of the slurry for producing the coating layer may be controlled, thereby improving the convenience of producing an electrochemical device.

[0090] According to one embodiment of the present invention, the first polymer binder may be in solution form. In the present specification, 'solution form' may mean that it is dissolved by a solvent, dispersion medium, or electrolyte used to prepare a slurry and thus does not maintain the shape of the particles, and may mean that the solubility by the solvent, dispersion medium, or electrolyte used to prepare the slurry is greater than 50% (w / w). As described above, by selecting the first polymer binder as being in solution form, the coating layer included in the separator can be formed with a uniform thickness.

[0091] According to one embodiment of the present invention, the first polymer binder may be in particle form. In the present specification, 'particle form' may mean that it maintains the shape of a particle without being dissolved by a solvent, dispersion medium, or electrolyte used to prepare a slurry, and may mean that the solubility by the solvent, dispersion medium, or electrolyte used to prepare the slurry is 50% (w / w) or less. As described above, by selecting the first polymer binder as being in particle form, the porosity of the coating layer included in the separator can be improved.

[0092] According to one embodiment of the present invention, the average particle diameter (D) of the first polymer binder 50 ) has no special limitations, but in order to form a coating layer (130) of uniform thickness and an appropriate porosity, it is preferably in the range of 0.1 ㎛ or more and 1 ㎛ or less. Specifically, the average particle diameter (D of the first polymer binder 50 ) may be 0.2 ㎛ or more and 0.9 ㎛ or less, 0.3 ㎛ or more and 0.8 ㎛ or less, 0.4 ㎛ or more and 0.7 ㎛ or less, or 0.5 ㎛ or more and 0.6 ㎛ or less. In the above-described range, the average particle diameter (D of the first polymer binder 50 ) can improve the dispersibility in the slurry prepared for manufacturing the coating layer, and reduce the thickness of the formed coating layer.

[0093] According to one embodiment of the present invention, the first polymer binder may be a polyvinylidene-based resin. Specifically, according to one embodiment of the present invention, the polyvinylidene-based resin may be a copolymer of polyvinylidene fluoride (PVdF) and hexafluoropropylene (HFP). As described above, by selecting the first polymer binder as a polyvinylidene-based resin, the porosity of the separator can be maintained, and even if the coating layer is wetted by an electrolyte after activation of the electrochemical device, the adhesive strength can be maintained. Furthermore, the stiffness of the electrochemical device can be improved, and bending of the separator can be prevented.

[0094] According to one embodiment of the present invention, the polyvinylidene-based binder may be an aqueous resin. Specifically, by selecting the polyvinylidene-based resin as an aqueous resin, pollutants emitted during the manufacturing process of the separator can be minimized, thereby reducing the manufacturing cost of the electrochemical device.

[0095] In this specification, “aqueous” may mean soluble in water, and the aqueous system may mean having a solubility in water of more than 50% (w / w).

[0096] According to one embodiment of the present invention, the first polymer binder may be a polyvinylidene-based resin having a hexafluoropropylene (HFP) content of 1 wt% or more and 50 wt% or less. Specifically, the first polymer binder may be a polyvinylidene-based resin having a hexafluoropropylene (HFP) content of 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 first polymer binder as a polyvinylidene-based resin having a hexafluoropropylene content of 1 wt% or more and 50 wt% or less, the porosity of the separator can be maintained, and even if the coating layer is wetted by an electrolyte after activation of the electrochemical device, the adhesive strength can be maintained. In the present specification, the degree of substitution of the polyvinylidene-based resin may mean the weight ratio containing hexafluoropropylene.

[0097] According to one embodiment of the present invention, the total content of the first polymer binder may be 30 parts by weight or less with respect to 100 parts by weight of the coating layer (130). Specifically, the total content of the first polymer binder may be more than 0 parts by weight and less than or equal to 30 parts by weight, 1 parts by weight or more and 27 parts by weight or less, 2 parts by weight or more and 25 parts by weight or less, 3 parts by weight or more and 22 parts by weight or less, 4 parts by weight or more and 21 parts by weight or less, 5 parts by weight or more and 20 parts by weight or less, 6 parts by weight or more and 19 parts by weight or less, 7 parts by weight or more and 18 parts by weight or less, 8 parts by weight or more and 17 parts by weight or less, 9 parts by weight or more and 16 parts by weight or less, 10 parts by weight or more and 15 parts by weight or less, 11 parts by weight or more and 14 parts by weight or less, or 12 parts by weight or more and 13 parts by weight or less with respect to 100 parts by weight of the coating layer (130). By controlling the total content of the first polymer binder within the above-described range, the ease of assembly can be improved in the process of assembling the electrode.

[0098] According to one embodiment of the present invention, the porosity of the coating layer (130) may be 30% by volume or more. Specifically, the porosity of the coating layer (130) may be 30% by volume or more and 70% by volume or less, 32% by volume or more and 68% by volume or less, 34% by volume or more and 66% by volume or less, 36% by volume or more and 64% by volume or less, 38% by volume or more and 62% by volume or less, 40% by volume or more and 60% by volume or less, 42% by volume or more and 58% by volume or less, 44% by volume or more and 56% by volume or less, 46% by volume or more and 54% by volume or 48% by volume or more and 52% by volume. By controlling the porosity of the coating layer (130) within the above-described range, it is possible to maintain the movement of ions in the separator and prevent an increase in resistance of the separator. By controlling the porosity of the coating layer within the above-described range, mechanical properties that can withstand the pressing process for bonding with the electrode can be secured, adhesive strength can be secured without the surface opening ratio becoming too high, and ion permeability can be improved.

[0099] According to one embodiment of the present invention, an adhesive layer including a second polymer binder may be further included on at least a portion of the coating layer. Fig. 3 is a schematic diagram of a separator for an electrochemical device according to one embodiment of the present invention. Specifically, Fig. 3(a) is a separator for an electrochemical device having a coating layer and an adhesive layer provided on one surface of a polymer porous substrate, and Fig. 3(b) is a separator for an electrochemical device having a coating layer and an adhesive layer provided on both surfaces of a polymer porous substrate. As shown in Fig. 3, the adhesive layer may be provided on only one surface of the separator, or the adhesive layer may be provided on both surfaces of the separator. Fig. 4 is a schematic diagram of a separator for an electrochemical device according to one embodiment of the present invention. Specifically, FIG. 4(a) is a separator for an electrochemical device having an adhesive layer including a second polymer binder in the form of a coating layer particle on one side of a polymer porous substrate, and FIG. 4(b) is a separator for an electrochemical device having a coating layer and an adhesive layer on both sides of a polymer porous substrate. Specifically, as shown in FIG. 4, the adhesive layer may be provided on the entire coating layer or on at least a portion of the coating layer. More specifically, the area on which the adhesive layer is provided may be 1% to 99%, 5% to 95%, 10% to 90%, 15% to 85%, 20% to 80%, 25% to 75%, or 30% to 70% of the area of ​​the entire coating layer. As described above, by including the adhesive layer on the coating layer, dry adhesion and wet adhesion with respect to the electrode can be improved.

[0100] According to one embodiment of the present invention, the second polymer binder may be in particle form, solution form, or a combination thereof. By selecting the second polymer binder from the above-described types, dry adhesion and wet adhesion with the electrode can be improved.

[0101] 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 as being in particle form, the porosity of the separator can be maintained at a high level while improving the adhesion to the electrode.

[0102] According to one embodiment of the present invention, the first polymer binder and the second polymer binder may be the same as or different from each other. By selecting the first polymer binder and the second polymer binder as described above, the adhesive strength between the coating layer and the adhesive layer can be controlled, the second polymer binder can be prevented from being dissolved by the electrolyte, and the resistance of the electrochemical device can be minimized.

[0103] According to one embodiment of the present invention, the second polymer binder may be provided on a portion of the coating layer by a spray method, bar coating, spin coating, or dip coating method. By selecting a method for providing the second polymer binder from those described above, the second polymer binder can be easily positioned on the coating layer.

[0104] 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 a coating layer (130) including a first polymer binder and inorganic particles (S10); applying the slurry for the coating layer on at least one surface of a porous polymer substrate (110) (S30); and drying the slurry for the coating layer to form a coating layer (130) (S50).

[0105] 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 activation of an electrochemical device to improve stiffness or prevent a pouch-type electrochemical device from bending.

[0106] According to one embodiment of the present invention, the slurry for the coating layer may be maintained in a wet state to form at least two layers on the porous polymer substrate by gravity before drying to form the coating layer.

[0107] According to one embodiment of the present invention, after applying the slurry for the coating layer to one surface of the porous polymer substrate (110) (S30), the slurry can be maintained in a wet state for at least 1 minute to allow phase separation of the coating layer by gravity.

[0108] According to one embodiment of the present invention, phase separation by gravity may mean that the slurry is separated to include one or more phases due to a difference in density between the first polymer binder and the inorganic particles.

[0109] According to one embodiment of the present invention, the inorganic particles have a higher density than the first polymer binder, so that the inorganic particles form a bottom phase, and the first polymer binder particles form a layer on the bottom. Accordingly, phase separation may be the formation of a clearly separated phase, and a concentration gradient of the first polymer binder or the inorganic particles may be formed between the upper and lower portions.

[0110] According to one embodiment of the present invention, the method for manufacturing the electrochemical device separator (100) includes a step (S10) of mixing a slurry for a coating layer including a first polymer binder and inorganic particles. By including the step (S10) of mixing the slurry for the coating layer as described above, a coating layer can be easily formed on the separator.

[0111] According to one embodiment of the present invention, a first polymer binder may be dispersed in water, which is a suitable dispersion medium, to prepare a polymer emulsion, thereby providing a slurry for a coating layer. As described above, by dispersing the first polymer binder in water, which is a suitable dispersion medium, to prepare a polymer emulsion, thereby providing a slurry for a coating 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.

[0112] According to one embodiment of the present invention, the inorganic particles may be added and dispersed in the polymer emulsion. The content ratio of the inorganic particles and the polymer binder is as described above, and is 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.

[0113] According to one embodiment of the present invention, a slurry for a coating layer can be prepared by dispersing a first polymer binder and the inorganic particles in water as a dispersion medium. Specifically, a slurry for a coating layer can be prepared by dispersing the first polymer binder, the inorganic particles, and the dispersant in water as a dispersion medium.

[0114] According to one embodiment of the present invention, the content of the dispersant may be 0.1 parts by weight or more and 3.0 parts by weight or less based on 100 parts by weight of the slurry for the coating layer. Specifically, the content of the dispersant may be 2.0 parts by weight or more and 3.0 parts by weight or less based on 100 parts by weight of the slurry for the coating layer. By controlling the content of the dispersant as described above, the dispersibility of each component in the slurry for the coating layer can be improved.

[0115] According to one embodiment of the present invention, the dispersant may be polyacrylic acid, but is not limited thereto, and a commonly used dispersant may be selected and used.

[0116] According to one embodiment of the present invention, the solid content of the slurry for the coating layer may be 10 wt% or more and 50 wt% or less. Specifically, the solid content of the slurry for the coating layer may be 15 wt% or more and 40 wt% or less, 20 wt% or more and 35 wt% or less, or 15 wt% or more and 40 wt% or less. By controlling the solid content of the slurry for the coating layer within the above-described range, the workability of the coating layer manufacturing process can be improved.

[0117] According to one embodiment of the present invention, the method for manufacturing the electrochemical device separator (100) includes a step (S30) of applying the slurry for the coating layer on at least one surface of the porous polymer substrate (110). By including the step of applying the slurry for the coating layer on at least one surface of the porous polymer substrate (110) as described above, the coating layer (130) can be formed with a single application, and the slurry for the coating layer has an excess of inorganic particles in a portion close to the porous polymer substrate (110) due to separation between the inorganic particles and the first polymer binder, and an excess of the first polymer binder in a portion far from the porous polymer substrate (110), thereby improving the adhesive force with the electrode and improving the porosity of the separator.

[0118] In the present specification, the presence of excess may mean a content exceeding 50 wt% in the relevant portion, and the portion close to and the portion far from the porous polymer substrate (110) may be distinguished based on an imaginary line that accounts for 1 / 2 of the thickness of the coating layer.

[0119] 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 can be used. For example, various methods such as bar coating, dip coating, die coating, roll coating, comma coating, or a mixture thereof can be used. More specifically, the method for applying the slurry for the coating layer to the surface of the porous polymer substrate (110) can be bar coating using a doctor blade.

[0120] According to one embodiment of the present invention, the method for manufacturing the electrochemical device separator (100) includes a step (S50) of drying the slurry for the coating layer to form a coating layer (130). Specifically, the drying may be performed using a heat gun with wind at 50° C. By including the step (S50) of drying the slurry for the coating layer to form a coating layer (130) as described above, damage to the coating layer can be minimized, and the dispersion medium included in the slurry can be easily removed.

[0121] According to one embodiment of the present invention, the temperature of the drying process may be 25°C or more and 75°C or less. Specifically, the temperature of the drying process may be 30°C or more and 70°C or less, 35°C or more and 65°C or less, 40°C or more and 60°C or less, or 45°C or more and 55°C or less. By controlling the temperature of the drying process within the above-described range, the denaturation of the porous polymer substrate can be prevented, and the dispersion medium can be effectively removed.

[0122] 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.

[0123] According to one embodiment of the present invention, the separator (100) is interposed between the cathode and the anode and is manufactured into an electrochemical device by a lamination process in which heat and / or pressure are applied to bond the membrane.

[0124] In one embodiment of the present invention, the lamination process can be performed by a roll press device including a pair of pressure rollers. That is, the negative electrode, separator, and positive electrode can be sequentially laminated and placed between the pressure rollers to achieve interlayer bonding.

[0125] In one embodiment of the present invention, the lamination process can be performed by a hot pressing method.

[0126] One embodiment of the present invention provides an electrochemical device (1000) including: an anode (300); a cathode (500); and a separator (100) interposed between the anode (300) and the cathode (500).

[0127] An electrochemical device according to one embodiment of the present invention can improve the lifespan and enhance explosion safety by preventing explosion due to gas generation.

[0128] Figure 5 is a schematic diagram of an electrochemical device according to one embodiment of the present invention. Referring to Figure 5, the electrochemical device according to one embodiment of the present invention will be described in detail.

[0129] According to one embodiment of the present invention, the electrochemical device may have a gas generation amount of 7,000 μL or less after being heated at 130° C. for 1 hour. By controlling the gas generation amount of the electrochemical device within the above-described range, the explosion safety of the electrochemical device can be improved, and the output and capacity retention rate can be improved.

[0130] According to one embodiment of the present invention, the resistance of the separator in the electrochemical device may be 90 Ω or less. Specifically, the resistance of the separator in the electrochemical device may be 50 Ω or more and 90 Ω or less, 70 Ω or more and 86 Ω or less, 72 Ω or more and 84 Ω or less, 73 Ω or more and 80 Ω or less, or 73 Ω or more and 74 Ω or less. By controlling the resistance range of the separator within the above-described range, the amount of gas generated can be controlled, and the output and capacity maintenance rate of the electrochemical device can be improved.

[0131] According to one embodiment of the present invention, the capacity retention rate of the electrochemical device may be 80% or more. Specifically, the capacity retention rate of the electrochemical device may be 80% or more and less than 100%, 80% or more and 95% or less, 82% or more and 91% or less, or 85% or more and 88% or less. By controlling the amount of gas generated, the output of the electrochemical device can be improved.

[0132] 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 may include a primary battery and a secondary battery.

[0133] In this specification, the secondary battery is capable of being charged and discharged, and may refer to a lithium secondary battery, a nickel-cadmium battery, a nickel-hydrogen battery, etc.

[0134] In one embodiment of the present invention, 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 a negative electrode.

[0135] According to one embodiment of the present invention, the positive electrode may have 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 may be 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 x A 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.

[0136] According to one embodiment of the present invention, the negative electrode may have 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 may include 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.

[0137] 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.

[0138] 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.

[0139] 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.

[0140] According to one embodiment of the present invention, the positive electrode includes a positive electrode active material layer, and the coating layer of the separator may be in direct contact with the positive electrode active material layer.

[0141] According to one embodiment of the present invention, the coating layer may have improved thermal shrinkage. Accordingly, the minimum thermal shrinkage of the coating layer can help to completely maintain the physical state of the separator-anode interface during thermal changes due to charge / discharge cycles. Ultimately, this can improve electrochemical performance, such as battery capacity maintenance and cycle stability. Therefore, the stable separator-anode interface can extend the life of the electrochemical device, as realized by reduced mechanical stress and enhanced cycle stability.

[0142] According to one embodiment of the present invention, the negative electrode includes a negative electrode active material layer, and the coating layer of the separator may be in direct contact with the negative electrode active material layer.

[0143] The minimum thermal shrinkage of the coating layer can help maintain the physical state of the separator-cathode interface completely during thermal changes due to charge / discharge cycles. Ultimately, this can improve electrochemical performance, such as battery capacity retention and cycle stability. Therefore, the stable separator-cathode interface can extend the life of the electrochemical device, as realized by reduced mechanical stress and enhanced cycle stability.

[0144] 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).

[0145] 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.

[0146] 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).

[0147] 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.

[0148] 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.

[0149] 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.

[0150] 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.

[0151] 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.

[0152] <Example 1>

[0153] 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.

[0154] A slurry (solid content concentration of 30 wt%) for a coating layer was prepared by adding 94.6 wt% of BaTiO3 (average particle diameter: 2.0 ㎛, crystal grain size: 1.0 ㎛) as inorganic particles, 3 wt% of styrene-butyl acrylate (glass transition temperature: 40 ℃) as an acrylic binder as a first polymer binder, and 2.4 wt% of polyacrylic acid as a dispersant to water as a solvent.

[0155] The slurry for the coating layer was applied to both sides of the surface of the porous polymer substrate using a doctor blade by a bar coating method, and dried with wind at 50°C using a heat gun to form a coating layer with a thickness of 5 μm on each side, thereby manufacturing a separator with a total thickness of 14 μm.

[0156] <Example 2>

[0157] A separation membrane was manufactured in the same manner as in Example 1, except that the inorganic particles were BaTiO3 (particle size: 2.0 μm, crystal grain size: 0.01 μm).

[0158] <Example 3>

[0159] A separation membrane was manufactured in the same manner as in Example 1, except that the inorganic particles were BaTiO3 (particle size: 2.0 μm, crystal grain size: 0.1 μm).

[0160] <Example 4>

[0161] A separation membrane was manufactured in the same manner as in Example 1, except that the inorganic particles were BaTiO3 (particle size: 2.0 μm, crystal grain size: 0.5 μm).

[0162] <Example 5>

[0163] A separation membrane was manufactured in the same manner as in Example 1, except that the inorganic particles were BaTiO3 (particle size: 2.0 μm, crystal grain size: 0.8 μm).

[0164] <Example 6>

[0165] A separation membrane was manufactured in the same manner as in Example 1, except that the inorganic particles were BaTiO3 (particle size: 2.0 μm, crystal grain size: 1.2 μm).

[0166] <Example 7>

[0167] A separation membrane was manufactured in the same manner as in Example 1, except that the inorganic particles were SrTiO3 (particle size: 2.0 μm, crystal grain size: 1.0 μm).

[0168] <Example 8>

[0169] A separation membrane was manufactured in the same manner as in Example 1, except that the inorganic particles were LiNdO3 (particle size: 2.0 μm, crystal grain size: 1.0 μm).

[0170] <Example 9>

[0171] A separation membrane was manufactured in the same manner as in Example 1, except that the inorganic particles were BaTiO3 (particle size: 2.0 μm, crystal grain size: 0.001 μm).

[0172] <Example 10>

[0173] A separation membrane was manufactured in the same manner as in Example 1, except that the inorganic particles were Al2O3 (particle size: 2.0 ㎛, crystal grain size: 2.0 ㎛).

[0174] <Comparative Example 1>

[0175] A separation membrane was manufactured in the same manner as in Example 1, except that the inorganic particles were BaTiO3 (particle size: 2.0 μm, crystal grain size: 2.2 μm).

[0176] The types of inorganic particles, particle sizes of inorganic particles, and crystal grain sizes of Examples 1 to 10 and Comparative Example 1 are summarized in Table 1 below.

[0177] Type of inorganic particleInorganic particle size (㎛)Crystal grain size of inorganic particle (㎛)Example 1BaTiO32.01.0Example 2BaTiO32.00.01Example 3BaTiO32.00.1Example 4BaTiO32.00.5Example 5BaTiO32.00.8Example 6BaTiO32.01.2Example 7SrTiO32.01.0Example 8LiNdO32.01.0Example 9BaTiO32.00.001Example 10Al2O32.02.0Comparative example 1BaTiO32.02.2

[0178] <Manufacturing of electrochemical devices>

[0179] 1) Manufacturing of the anode

[0180] Cathode active material (LiNi) 0.8 Mn 0.1 Co 0.1O2), 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).

[0181] 2) Manufacturing of cathode

[0182] 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).

[0183] 3) Lamination process

[0184] The separators of Examples 1 to 10 and Comparative Example 1 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 70°C and 5.2 MPa for 10 seconds.

[0185]

[0186] <Experimental Example 1: Dielectric Constant Measurement>

[0187] For the inorganic particles used in Examples 1 to 10 and Comparative Example 1, samples were prepared by forming pellets having a diameter of 100 mm and a thickness of 4 mm using high-pressure compression molding. The dielectric constants of the samples were measured using the ASTM D 150 standard test method, and the results are summarized in Table 2 below.

[0188] <Experimental Example 2: Measurement of Gas Generation Amount>

[0189] The amount of gas generated after storing the electrochemical device including the membrane of Examples 1 to 10 and Comparative Example 1 at 72°C for 3 days was measured using gas chromatography and then summarized in Table 2 below.

[0190] <Experimental Example 3: Resistance Measurement>

[0191] For the electrochemical devices including the separators of Examples 1 to 10 and Comparative Example 1, a 1C CC current was applied at 25°C at an operating voltage of 2.5 V to 4.2 V and an SOC50 state, and the resistance was calculated from the voltage change that occurred for 10 seconds using the following mathematical formula 1 and summarized in Table 2.

[0192] [Mathematical Formula 1]

[0193] R=ΔV / I

[0194] <Experimental Example 4: Measurement of Capacity Retention Rate>

[0195] The electrochemical devices using the separators of Examples 1 to 6 and Comparative Example 1 were charged and discharged once at 0.1 C in the voltage range of 3.0 V to 4.4 V using an electrochemical charger / discharger in a 45°C chamber, and then the life characteristics were measured for 200 cycles while charging at 1.0 C and discharging at 1.0 C. At this time, the life characteristics were expressed as the capacity retention rate by calculating the ratio of the discharge capacity after 200 cycles to the discharge capacity at the first cycle using the following mathematical formula 2, and are summarized in Table 2 below.

[0196] The above capacity retention rate was calculated using the following mathematical formula 2.

[0197] [Equation 2]

[0198] Capacity retention rate (%) = (discharge capacity after 200 cycles / discharge capacity after 1 cycle) × 100

[0199] Dielectric constantGas generation amount(㎕)Resistance(Ω)Capacitance retention rate(%)Example 15,3001,01471.292.4Example 2603,34585.485.4Example 35002,67183.687.7Example 42,3001,73677.689.3Example 54,1001,29973.390.8Example 61,5002,23679.988.1Example 77,00089972.290.8Example 86,20095773.189.8Example 9403,02784.386.7Example 1098,23798.977.5Comparative example 11,40010,74886.075.0

[0200] Referring to Table 2 above, it was confirmed that Examples 1 to 10, in which the crystal grain size of the inorganic particles was controlled within a specific range, showed a reduced amount of gas generation and a high capacity retention rate.

[0201] In this regard, it was confirmed that Comparative Example 1, which did not satisfy the crystal grain size range of the above-mentioned inorganic particles, had an increased amount of gas generation and a low capacity retention rate.

[0202] The electrochemical device separator and electrochemical device according to one embodiment of the present invention can improve the explosion safety of the electrochemical device by reducing gas generated during the operation of the electrochemical device by controlling the crystal grain size of the inorganic particles.

[0203] [Explanation of symbols]

[0204] 100: Dielectric membrane for electrochemical devices

[0205] 110: Porous polymer substrate

[0206] 130: Coating layer

[0207] 150: Adhesive layer

[0208] 300: Bipolar

[0209] 500: negative

[0210] 1000: Electrochemical devices

Claims

porous polymer substrate; and A coating layer provided on at least one surface of the porous polymer, and including inorganic particles and a first polymer binder; A separator for an electrochemical device, wherein the crystal grain size of the above-mentioned inorganic particles is 2 ㎛ or less. In claim 1, A separator for an electrochemical device, wherein the average particle diameter of the above-mentioned inorganic particles is 0.1 um or more and 10.0 um or less. In claim 1, A separator for an electrochemical device, wherein the dielectric constant of the above-mentioned inorganic particles is 10 or more. In claim 1, The above inorganic particles are a separator for an electrochemical device comprising a metal oxide represented by the following chemical formula 1: [Chemical Formula 1] A x B y O z The above A is one selected from the group consisting of Ba, Sr, Pb, Bi, Nai, K, Ca, Y, Gd, La, Li, or these, The above B is one selected from the group consisting of Ti, Zr, Fe, Nb, Mn, Nb, Ta or these, The above 0 < x ≤ 5, 0 < y ≤ 5 and 0 < z ≤ 5. In claim 1, A separator for an electrochemical device, wherein the content of the above-mentioned inorganic particles is 70 parts by weight or more with respect to 100 parts by weight of the above-mentioned coating layer. In claim 1, A separator for an electrochemical device, wherein the first polymer binder is an acrylic resin. In claim 1, A separator for an electrochemical device further comprising an adhesive layer comprising a second polymer binder on at least a portion of the coating layer. In claim 7, A separator for an electrochemical device, wherein the second polymer binder is in particle form. An electrochemical device comprising: an anode; a cathode; and a separator interposed between the anode and the cathode, the separator being any one of claims 1 to 8. In claim 9, An electrochemical device having a gas generation amount of 7,000 ㎕ or less after heating at 130 ℃ for 1 hour.

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