Separator and electrochemical element including the same

Abstract

To provide a separator and an electrochemical element having the separator.SOLUTION: The separator according to one aspect of the present disclosure includes: a porous base material; and an inorganic particle layer formed on at least one surface of the porous base material, the layer containing a binder and inorganic particles. The Gurley permeability is 10 to 250 sec / 100 cc, the punching intensity is at least 0.3 N / μm, the tensile strength in a mechanical direction and a width direction is at least 1500 kgf / cm2, the thermal shrinkage in the mechanical direction and in the width direction measured after the separator is left in a condition under the temperature of 130°C for 60 minutes is 5% or less, and a saturated moisture content measured by the Karl-Fischer method is in the range of 350-1000 ppm.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a separator and an electrochemical element including the same.

Background Art

[0002] Recently, with the increasing demand for environmentally friendly energy, research on electrochemical elements has been conducted in various fields such as electronic devices such as mobile phones and PCs, and electric vehicles.

[0003] An insulating separator interposed between a positive electrode and a negative electrode has been studied in the direction of thinning the thickness for the high-capacity / high-output characteristics of an electrochemical element. However, when the thickness of the separator is reduced, there is a problem that the mechanical strength and / or heat resistance decreases. When the mechanical strength and / or heat resistance decreases, the safety problems during the battery manufacturing process and use increase. As an example, there may be a short circuit between electrodes due to damage or deformation of the separator caused by an increase in the temperature inside the battery, and the risk of battery overheating or fire may increase.

[0004] Therefore, it is necessary to develop a separator having a thin thickness and improved mechanical strength and heat resistance as described above. In addition, in conjunction with this, it is necessary to develop a separator having a high permeability for improving the capacity and output.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] According to one aspect of the present disclosure, it is possible to provide a separator having excellent heat resistance and adhesiveness even with a thin thickness, and an electrochemical element including the same.

[0007] According to another aspect of the present disclosure, it is possible to provide a separator having improved mechanical strength and permeability even with a thin thickness, and an electrochemical element including the same.

[0008] According to another aspect of the present disclosure, it is possible to provide an electrochemical element having excellent resistance characteristics and thermal safety.

[0009] The separator of the present disclosure is widely applicable in the fields of green technologies such as electric vehicles, battery charging stations, and other uses of batteries, such as solar power generation and wind power generation. Further, the separator of the present disclosure can be used in eco-friendly electric vehicles, hybrid vehicles, etc. for suppressing air pollution and greenhouse gas emissions to prevent climate change.

Means for Solving the Problems

[0010] The separator according to the present disclosure includes a porous substrate and an inorganic particle layer formed on at least one surface of the porous substrate and containing a binder and inorganic particles, and has a Gurley permeability of 10 to 250 sec / 100 cc, a puncture strength of 0.3 N / μm or more, a tensile strength in the machine direction and the width direction of 1500 kgf / cm 2 or more, and after being left at 130° C. for 60 minutes, the thermal shrinkage rates in the machine direction and the width direction measured are 5% or less, and the saturated moisture content measured by the Karl Fischer method is 350 to 1000 ppm.

[0011] In one embodiment, the Gurley permeability may be 90 to 230 sec / 100 cc, and the saturated moisture content may be 450 to 1000 ppm.

[0012] In one embodiment, the average thickness of the porous substrate is 5 to 15 μm, and the ratio of the average thickness of the porous substrate to the average thickness of the separator may be 0.7 or more.

[0013] In one embodiment, the total thickness of the inorganic particle layer formed on the porous substrate may be 3.2 μm or less.

[0014] In one embodiment, the binder may include a polyacrylamide-based resin.

[0015] In one embodiment, the polyacrylamide-based resin can be a copolymer containing units derived from (meth)acrylamide-based monomers.

[0016] In one embodiment, the polyacrylamide-based resin may include structural units derived from (meth)acrylamide-based monomers and structural units derived from (meth)acrylic monomers containing a hydroxy group.

[0017] In one embodiment, the polyacrylamide-based resin may have a weight average molecular weight of 100,000 to 2,000,000 g / mol.

[0018] In one embodiment, the binder may further include any one or two or more aqueous polymers selected from the group consisting of polyvinyl alcohol, polyvinylidene fluoride, carboxymethyl cellulose, styrene butadiene rubber, polyacrylic acid, polyethylene glycol, polyacrylonitrile, polyvinyl pyrrolidone, and copolymers thereof.

[0019] In one embodiment, the content of the aqueous polymer may be 0.1 to 30% by weight of the total content of the binder.

[0020] In one embodiment, the inorganic particles may have a BET specific surface area of 3 to 7 m 2 / g.

[0021] In one embodiment, the inorganic particles may have an average particle size (D50) of 0.5 to 1.5 μm.

[0022] In one embodiment, the inorganic particles may include any one or two or more selected from the group consisting of metal hydroxides, metal oxides, metal nitrides, and metal carbides.

[0023] In one embodiment, the inorganic particle layer may have a weight ratio of inorganic particles to binder of 50:50 to 99.9:0.1.

[0024] In one embodiment, the inorganic particle layer may be formed at 0.5 to 10 g / m 2 It may be formed as such.

[0025] The present disclosure also provides an electrochemical element including the separator as described above.

Advantages of the Invention

[0026] The separator according to the present disclosure can have excellent heat resistance and adhesiveness even with a thin thickness.

[0027] Also, the separator according to the present disclosure can have excellent mechanical strength and permeability even with a thin thickness.

[0028] The present disclosure can also provide an electrochemical element having excellent resistance characteristics and thermal safety by including the separator according to one embodiment.

Embodiments for Carrying Out the Invention

[0029] Hereinafter, the present disclosure will be described in detail. However, this is merely exemplary, and the present disclosure is not limited to the specific embodiments described exemplarily.

[0030] Also, the singular forms used in the specification and the appended claims can be intended to include the plural forms as well, unless otherwise specifically stated in the context.

[0031] Also, the numerical ranges used in this specification include the lower limit value and the upper limit value, all values within that range, increments logically derived from the form and width of the defined range, among which all possible combinations of all limited values and the upper and lower limits of numerical ranges limited to different forms are included. In this specification, unless otherwise specified, values outside the numerical range that may occur due to experimental error or rounding of values are also included in the defined numerical range.

[0032] Furthermore, throughout the specification, stating that a certain component "comprises" means that it can further include other components, rather than excluding other components, unless there is a special description to the contrary.

[0033] In this specification, when a part such as a layer, film, region, plate, etc. is said to be "on" or "above" another part, this includes not only the case where it is "immediately above" the other part, but also the case where there are further other parts in between.

[0034] In this specification, "average particle size" means "D50", and "D50" means the particle size of inorganic particles corresponding to 50% in terms of the cumulative fraction based on volume. The average particle size can be derived from the results of the particle size distribution analyzed using S3500 manufactured by MICROTRAC, with samples taken in accordance with the ISO 13320-1 standard for the inorganic particles to be measured. Also, "D90" means the particle size of particles corresponding to 90% in terms of the cumulative fraction based on volume, and "D10" means the particle size of inorganic particles corresponding to 10% in terms of the cumulative fraction based on volume. D90 and D10 can be derived in the same manner as D50.

[0035] The present disclosure includes a porous substrate and an inorganic particle layer formed on at least one surface of the porous substrate, the inorganic particle layer containing a binder and inorganic particles, having a Gurley permeability of 10 to 250 sec / 100 cc, a puncture strength of 0.3 N / μm or more, a tensile strength in the machine direction and the width direction of 1500 kgf / cm 2 or more, and after being left at 130° C. for 60 minutes, having a thermal shrinkage rate in the machine direction and the width direction of 5% or less and a saturated moisture content measured by the Karl Fischer method of 350 to 1000 ppm, provides a separator.

[0036] Conventionally, when manufacturing a separator with a very thin thickness, it has not been possible to provide a separator that satisfies all of the physical properties as described above. However, as a result of intensive research by the inventors of the present disclosure, by simultaneously realizing the Gurley permeability, puncture strength, tensile strength, and saturated moisture content within the above ranges, it has been found that a separator excellent in heat resistance, adhesiveness, mechanical strength, and permeability can be provided even with a thin thickness.

[0037] In addition, an electrochemical device according to one embodiment can have all excellent resistance characteristics and thermal safety by including a separator that simultaneously satisfies the physical properties as described above. Specifically, an electrochemical device according to one embodiment can have a significantly low discharge resistance after 600 cycles and can have improved charge-discharge performance.

[0038] On the one hand, when the increase rate of the water content of the separator is large, even after being assembled into a battery, the remaining water content in the battery becomes high, and such an increase in the water content can cause a decrease in the battery capacity, such as by causing the decomposition of the electrolyte. Conventionally, in order to reduce the water content in the battery, it has been necessary to use an expensive packaging material such as aluminum. On the other hand, the separator according to the present disclosure can have the merit of a small increase rate of the water content due to storage by simultaneously satisfying the above-described physical properties including the saturated water content. Thereby, the present disclosure can provide a battery with excellent performance even when using a packaging material of a polyethylene material instead of an aluminum material with a low remaining water content in the battery. That is, according to the present disclosure, there is an advantage that the performance of the battery can be improved and the cost of the battery can be reduced.

[0039] As one embodiment, although the separator has a very thin inorganic particle layer in which the average thickness of the porous base material is 15 μm or less and the thickness of the porous base material is 0.7 times or more of the total thickness of the separator, it can have excellent mechanical properties, electrical properties, and thermal properties described later. The production of the separator having the above characteristics can be achieved by adjusting any one or more selected from the thickness of each layer of the separator, the size of the inorganic particles, the type of the binder, the surface area of the inorganic particles, and the saturated water content of the separator. As long as this can be achieved, the means is not particularly limited.

[0040] That is, conventionally, when manufacturing a separator with such a very thin thickness, it has not been possible to provide a separator that satisfies all of the above-described physical properties. However, as a result of intensive research by the inventors of the present disclosure, it has been found that a separator having excellent heat resistance, adhesiveness, mechanical strength, and permeability can be provided even with a thin thickness by simultaneously realizing the Gurley permeability, puncture strength, tensile strength, and saturated water content within the above-described ranges.

[0041] As one embodiment, the separator having the physical properties as described above together with the saturated water content may be manufactured using inorganic particles having a specific specific surface area. For example, in the separator according to one embodiment, the BET specific surface area of the inorganic particles contained therein is 3 m 2 / g or more, 4 m 2 / g or more, 7 m 2 / g or less, 6 m 2 / g or less, or may be a value between the above numerical values. Specifically, it may be 3 to 7 m 2 / g or 4 to 6 m 2 / g.

[0042] As one embodiment, the separator having the physical properties as described above may be manufactured by adjusting the ratio of the thickness of the porous base material and the inorganic particle layer contained therein to a specific value. For example, the ratio of the average thickness of the porous base material to the average thickness of the separator may be 0.7 or more, 0.75 or more, 0.77 or more, 0.99 or less, 0.9 or less, 0.85 or less, or a value between the above numerical values. Specifically, it may be 0.7 to 0.99, 0.75 to 0.9, or 0.77 to 0.85.

[0043] As one embodiment, the separator having the physical properties as described above may be manufactured using a specific resin as the binder contained therein. For example, the binder may include a polyacrylamide-based resin. Specifically, for example, it may be a polyacrylamide-based resin containing a structural unit derived from a (meth)acrylamide-based monomer and a structural unit derived from a (meth)acrylic-based monomer containing a hydroxy group.

[0044] According to one embodiment, the separator having the physical properties as described above may be manufactured by using a specific aqueous polymer together with the above-mentioned polyacrylamide-based resin as a binder. For example, the specific aqueous polymer may be any one or two or more selected from the group consisting of polyvinyl alcohol (PVA), polyvinylidene fluoride (PVDF), carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyacrylic acid (PAA), polyethylene glycol (PEG), polyacrylonitrile (PAN), polyvinylpyrrolidone (PVP), and copolymers thereof.

[0045] According to another embodiment, the separator having the physical properties as described above may be manufactured by using the above-mentioned polyacrylamide-based resin as a binder and using a porous substrate containing polar functional groups on the surface. Non-limiting examples of the polar functional groups include carboxyl groups, aldehyde groups, hydroxy groups, etc., but are not particularly limited. According to one example, the polar functional groups may be introduced by hydrophilic surface treatment, and according to one example, the hydrophilic surface treatment may be performed including one or more of corona discharge treatment and plasma discharge treatment.

[0046] Hereinafter, the separator will be described in more detail.

[0047] In one embodiment, the Gurley permeability of the separator may be 250 sec / 100 cc or less, 230 sec / 100 cc or less, 200 sec / 100 cc or less, 180 sec / 100 cc or less, 10 sec / 100 cc or more, 50 sec / 100 cc or more, 90 sec / 100 cc or more, 100 sec / 100 cc or more, or a value between the above numerical values. Specifically, the Gurley permeability may be 10 - 250 sec / 100 cc, 50 - 200 sec / 100 cc, 90 - 230 sec / 100 cc, or 100 - 180 sec / 100 cc. By satisfying the Gurley permeability within the above range, it may have excellent ionic conductivity, and due to the low internal resistance of the electrochemical element, the charge and discharge characteristics of the electrochemical element can be improved.

[0048] In one embodiment, the puncture strength of the separator may be 0.3 N / μm or more, 0.32 N / μm or more, 0.35 N / μm or more, 1.0 N / μm or less, 0.8 N / μm or less, 0.5 N / μm or less, or a value between the above numerical values. Specifically, the puncture strength may be 0.3 - 1.0 N / μm, 0.32 - 0.8 N / μm, or 0.35 N / μm - 0.5 N / μm.

[0049] In one embodiment, the separator has a tensile strength in the machine direction (MD) of 1500 - 2500 kgf / cm 2 or 1500 - 2000 kgf / cm 2 may also be acceptable.

[0050] In one embodiment, the separator has a tensile strength in the transverse direction (TD) of 1500 kgf / cm 2 or more, 1600 kgf / cm 2 or more, 1700 kgf / cm 2 or more, 2500 kgf / cm 2 or less, 2000 kgf / cm 2 or less, or a value between the above numerical values. Specifically, the tensile strength in the transverse direction is 1500 - 2500 kgf / cm 2, 1600~2000 kgf / cm 2 or 1700~2000 kgf / cm 2 may also be acceptable.

[0051] By satisfying the punching strength and tensile strength within the above ranges, it is excellent in resistance to external stress generated during the manufacture of the electrochemical element and dendrites generated during charge and discharge of the electrochemical element, and can ensure the safety of the electrochemical element.

[0052] The separator according to one embodiment can have excellent heat resistance even with a thin thickness. In one embodiment, after leaving the separator at 130 °C for 60 minutes, the measured thermal shrinkage rates in the machine direction and width direction may be 5% or less, may be 4% or less, may be 3% or less, 2% or less, or 1.5% or less.

[0053] In one embodiment, the saturated moisture content is measured after leaving it in a thermo-hygrostat set at 40 °C and 90% relative humidity for 24 hours, and may be 350 ppm or more, 450 ppm or more, 500 ppm or more, 550 ppm or more, 600 ppm or more, 1000 ppm or less, 900 ppm or less, 800 ppm or less, 750 ppm or less, or a value between the above numerical values. Specifically, the saturated moisture content may be 350~1000 ppm, 450~1000 ppm, 500~900 ppm, 550~800 ppm, or 600~750 ppm.

[0054] In one embodiment, the average thickness of the porous substrate is 5~15 μm, and the ratio of the average thickness of the porous substrate to the average thickness of the separator may be 0.7 or more. The separator according to one embodiment can simultaneously achieve the Gurley permeability, punching strength, tensile strength, and saturated moisture content within the above ranges even under the thickness conditions within the above ranges. Thereby, the thinning of the separator for secondary batteries is possible, which is suitable for application to high-capacity / high-output batteries.

[0055] In one embodiment, the average thickness of the porous substrate is not necessarily limited thereto, but may be 5 μm or more, 8 μm or more, 15 μm or less, 12 μm or less, or a value between the above numerical values. Specifically, the average thickness of the porous substrate may be 5 to 15 μm or 8 to 12 μm.

[0056] In one embodiment, the ratio of the average thickness of the porous substrate to the average thickness of the separator may be 0.7 or more, 0.75 or more, 0.77 or more, 0.99 or less, 0.9 or less, 0.85 or less, or a value between the above numerical values. Specifically, the ratio of the average thickness of the porous substrate to the average thickness of the separator may be 0.7 to 0.99, 0.75 to 0.9, or 0.77 to 0.85.

[0057] In one embodiment, the average thickness of the separator is not necessarily limited thereto, but may be 7 μm or more, 10 μm or more, 12 μm or more, 20 μm or less, 15 μm or less, or a value between the above numerical values. Specifically, the average thickness of the separator may be 7 to 20 μm, 10 to 15 μm, or 12 to 15 μm.

[0058] In one embodiment, the inorganic particle layer can be coated on one or both surfaces of the porous substrate. When the inorganic particle layer is coated on both surfaces of the porous substrate, the thicknesses of the inorganic particle layers coated on one surface and the other surface may be the same or different from each other.

[0059] In one embodiment, the total thickness of the inorganic particle layer formed on the porous substrate is not necessarily limited thereto, but may be 4 μm or less, 3.5 μm or less, 1 μm or more, 1.5 μm or more, or a value between the above numerical values. Specifically, the total thickness of the inorganic particle layer may be 3.2 μm or less. More specifically, the total thickness of the inorganic particle layer may be 1 to 4 μm, 1.5 to 3.5 μm, 1 to 3.2 μm, or 1.5 to 3.2 μm.

[0060] In one embodiment, the binder may include a polyacrylamide-based resin.

[0061] In one embodiment, the polyacrylamide-based resin may be polyacrylamide or a copolymer containing the same. In one embodiment, the copolymer may be a block copolymer or a random copolymer. However, the copolymer described in the present disclosure is a polymer obtained by mixing and polymerizing two or more monomers together, and means a random copolymer.

[0062] In one embodiment, the polyacrylamide-based resin may be a copolymer containing units derived from (meth)acrylamide-based monomers and units derived from comonomers. Specifically, the polyacrylamide-based resin may include structural units derived from (meth)acrylamide-based monomers and structural units derived from (meth)acrylic monomers containing a hydroxy group.

[0063] The separator according to one embodiment is not a homopolymer derived from an acrylamide-based monomer, but by including the copolymer, the mechanical strength, gas permeability, heat resistance, and adhesiveness can be further improved. Further, the electrochemical element can have more excellent resistance characteristics and thermal safety by including the separator.

[0064] The unit derived from the (meth)acrylamide-based monomer of the polyacrylamide-based resin may be represented as in the following Chemical Formula 1.

[0065]

Chemical formula

[0066] In Chemical Formula 1, R 1 may be hydrogen or a C1-C6 alkyl group.

[0067] The unit derived from the (meth)acrylic monomer containing a hydroxy group of the polyacrylamide resin may be represented as in the following Chemical Formula 2.

[0068] [Chemical Formula]

[0069] In Chemical Formula 2, R 2 is hydrogen or a C1-C6 alkyl group. Further, L 1 may be a C1-C6 linear or branched alkylene group.

[0070] In the polyacrylamide resin according to one embodiment, the (meth)acrylamide monomer may be contained in an amount of 65 to 98 mol%, 70 to 97 mol%, or 75 to 95 mol%. The (meth)acrylic monomer containing a hydroxy group may be contained in an amount of 2 to 35 mol%, 3 to 30 mol%, or 5 to 25 mol%. When producing the polyacrylamide resin within the range of the content, sufficient adhesive strength can be obtained, and a more remarkable effect can be obtained with respect to the high-temperature shrinkage rate.

[0071] In one embodiment, the polyacrylamide resin may have a polyethylene glycol-equivalent weight-average molecular weight measured using gel permeation chromatography of 100,000 g / mol or more, 200,000 g / mol or more, 2,000,000 g / mol or less, 1,000,000 g / mol or less, 500,000 g / mol or less, or a value between the above numerical values. Specifically, the polyacrylamide resin may have a weight-average molecular weight of 100,000 to 2,000,000 g / mol, 200,000 to 1,000,000 g / mol, or 200,000 to 500,000 g / mol. According to one embodiment, when the weight-average molecular weight of the polyacrylamide resin satisfies the above range, the heat resistance and adhesiveness can be further improved.

[0072] The polyacrylamide-based resin may have a viscosity of an aqueous solution containing 10% by weight of solid content of 3000 cps or less, 2500 cps or less, 2000 cps or less, or 1500 cps or less, but is not limited thereto. When producing a coating slurry by mixing with inorganic particles within the above range, the viscosity of the slurry can be further reduced, and the coatability can be further improved, which is preferable.

[0073] As long as the polyacrylamide-based resin according to the above-described embodiment can be provided, the production method is not particularly limited. However, in one embodiment, the polyacrylamide-based resin may be provided by various known polymerization methods such as emulsion polymerization, suspension polymerization, bulk polymerization, solution polymerization, etc.

[0074] In one embodiment, the polyacrylamide-based resin may be obtained by copolymerization reaction from a mixture containing the monomer components described above and a polymerization initiator.

[0075] In one embodiment, the type of the polymerization initiator is not particularly limited as long as the copolymer can be obtained. However, in one embodiment, the polymerization initiator may be an azo-based initiator, a peroxide-based initiator, or a persulfate-based polymerization initiator such as potassium persulfate, sodium persulfate, ammonium persulfate, etc.

[0076] According to one embodiment, the polyacrylamide-based resin may be obtained by raising the temperature to 50 - 90°C or 60 - 80°C, then adding a polymerization initiator and carrying out a polymerization reaction.

[0077] In one embodiment, after the polymerization reaction is completed, the temperature may be lowered to room temperature (20 ± 5°C), and an aqueous solution of the polyacrylamide-based resin adjusted to a neutral state by adding a basic solution or the like may be produced.

[0078] In one embodiment, the binder may further include any one or two or more aqueous polymers selected from the group consisting of polyvinyl alcohol (PVA), polyvinylidene fluoride (PVDF), carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyacrylic acid (PAA), polyethylene glycol (PEG), polyacrylonitrile (PAN), polyvinylpyrrolidone (PVP), and copolymers thereof.

[0079] The separator according to one embodiment can further improve mechanical strength, gas permeability, heat resistance, and adhesiveness by using the above-mentioned aqueous polymer together with a polyacrylamide-based resin as a binder. In addition, the improvement of physical properties as described above can be achieved without performing pretreatment such as corona discharge treatment on the porous substrate, and there is an advantage in terms of process that time and material costs can be reduced.

[0080] In one embodiment, the content of the aqueous polymer may be 0.1 wt% or more, 1 wt% or more, 5 wt% or more, 30 wt% or less, 20 wt% or less, or 15 wt% or less of the total content of the binder. Or it may be a value between the above numerical values. Specifically, the content of the aqueous polymer may be 0.1 to 30 wt%, 1 to 20 wt%, or 5 to 15 wt%, but is not necessarily limited thereto.

[0081] In one embodiment, the degree of saponification of the aqueous polymer may be 80 to 95 mol%, specifically 85 to 90 mol%, but is not particularly limited thereto.

[0082] In one embodiment, the weight average molecular weight of the aqueous polymer may be 10,000 to 100,000 g / mol, specifically 30,000 to 70,000 g / mol, but is not particularly limited thereto.

[0083] In one embodiment, the porous substrate may be a polyolefin-based porous substrate such as polyethylene, polypropylene, or a copolymer thereof, but is not limited thereto, and any porous substrate known as a porous substrate for a separator of an electrochemical element may be used. In one embodiment, the porous substrate may be manufactured from a film or a sheet, but is not particularly limited.

[0084] In one embodiment, the porosity of the porous substrate may be 20 to 60%, specifically 30 to 60%, but is not limited thereto.

[0085] In one embodiment, the inorganic particle layer may include a binder and inorganic particles, and may be a porous inorganic particle layer in which the inorganic particles are connected and fixed by the binder to form pores. In one embodiment, the inorganic particle layer is provided on at least one surface of the porous substrate, and may occupy an area fraction of 60% or more, 70% or more, 80% or more, or 90% or more based on the entire surface of the porous substrate. Preferably, the inorganic particle layer may be formed on 100% of the area of the porous substrate.

[0086] In one embodiment, the inorganic particles are not limited as long as they are inorganic particles used in the technical field. As non-limiting examples, the inorganic particles may include any one or two or more selected from the group consisting of metal hydroxides, metal oxides, metal nitrides, and metal carbides. For example, the inorganic particles are magnesium oxide (MgO), magnesium hydroxide (Mg(OH) 2 ), alumina (Al 2 O 3 ), boehmite (γ-AlO(OH)), aluminum hydroxide (Al(OH) 3 ), silica (SiO 2) Silicon carbide (SiC), calcium oxide (CaO), titanium dioxide (TiO 2 ), strontium titanate (SrTiO 3 ), zinc oxide (ZnO), yttrium oxide (Y 2 O 3 ), zirconium oxide (ZrO 2 ), tin oxide (SnO 2 ) and cerium oxide (CeO 2 ), and may include any one or two or more selected from the group consisting of. From the viewpoint of battery stability and the like, specifically, the inorganic particles may be, for example, any one or two or more metal hydroxide particles selected from the group consisting of boehmite, aluminum hydroxide (Al(OH) 3 ) and magnesium hydroxide (Mg(OH) 2 ).

[0087] In one embodiment, the form of the inorganic particles is not limited and may be spherical, elliptical, needle-like, etc.

[0088] In one embodiment, the inorganic particles have a BET specific surface area of 3 m 2 / g or more, 4 m 2 / g or more, 7 m 2 / g or less, 6 m 2 / g or less, or a value between the above numerical values. Specifically, the BET specific surface area of the inorganic particles may be 3 to 7 m 2 / g or 4 to 6 m 2 / g. The present disclosure can provide a separator that satisfies the physical properties to be achieved by the present disclosure when the specific surface area within the above range is satisfied. Here, the BET specific surface area of the inorganic particles may be measured according to the ASTM C1069 method.

[0089] In one embodiment, the inorganic particles may have an average particle size (D50) of 0.5 μm or more, 0.6 μm or more, 1.5 μm or less, 1.0 μm or less, or a value between these numerical values. Specifically, the D50 of the inorganic particles may be 0.5 to 1.5 μm or 0.6 to 1.0 μm, but this can be changed as long as it does not deviate from the scope of the present disclosure.

[0090] In one embodiment, the weight ratio of the inorganic particles to the binder in the inorganic particle layer may be 50:50 to 99.9:0.1, 60:40 to 98:2, or 80:20 to 98:2, but is not particularly limited thereto.

[0091] In one embodiment, the inorganic particle layer is 0.5 to 10 g / m 2 , specifically 1 to 5 g / m 2 , more specifically 2.5 to 4 g / m 2 and may be formed, but is not particularly limited thereto.

[0092] Hereinafter, a method for manufacturing the separator of the present disclosure will be described.

[0093] The method for manufacturing a separator that simultaneously satisfies the above physical properties may include a first step of manufacturing a coating slurry containing a binder and inorganic particles, and a second step of applying the coating slurry to at least one surface of a porous substrate to form an inorganic particle layer.

[0094] The descriptions of the respective porous substrates, inorganic particle layers, inorganic particles, and binders are as described above, and specific descriptions are omitted.

[0095] The method for manufacturing the coating slurry in the first step may apply all ordinary methods known in the art without limitation, and is not particularly limited. However, by way of non-limiting example, the inorganic particles may be dispersed by stirring to produce a slurry, or the aggregated inorganic particles may be dispersed using a ball mill.

[0096] The coating slurry contains inorganic particles, a binder, and a solvent. The solvent may be water, lower alcohols such as ethanol, methanol, and propanol, dimethylformamide, acetone, tetrahydrofuran, diethyl ether, methylene chloride, DMF, N-methyl-2-pyrrolidone, hexane, cyclohexane, or a mixture thereof, but is not necessarily limited thereto.

[0097] In one embodiment, the solid content of the coating slurry is not particularly limited, and may be, for example, 1 to 50 wt%, 5 to 30 wt%, or 10 to 30 wt%, but is not limited thereto.

[0098] In one embodiment, the coating slurry may contain 50 to 99.9 wt% of inorganic particles and 0.1 to 50 wt% of a binder based on the total weight of the solid content. Specifically, it may contain 60 to 98 wt% of inorganic particles and 2 to 40 wt% of a binder, and more specifically, 80 to 98 wt% of inorganic particles and 2 to 20 wt% of a binder, but is not limited thereto.

[0099] As a method for applying the coating slurry in the second step, all ordinary methods known in the art may be applied without limitation. By way of non-limiting example, roll coating, spin coating, dip coating, bar coating, die coating, slit coating, inkjet printing, and combinations thereof may be applied. The applied slurry may be dried and formed as an inorganic particle layer. The drying for forming the inorganic particle layer is not particularly limited, but may be performed at 100°C or lower, or at 30 to 60°C.

[0100] In a specific embodiment, after drying to form the inorganic particle layer, the step of aging the porous substrate on which the inorganic particle layer is formed may not be further included. The aging may be performed at 50 to 150 °C or 60 °C to 120 °C, and the aging time may be 2 to 24 hours or 10 to 20 hours. More specifically, it may be performed for 10 to 15 hours in a temperature range of 70 to 120 °C. According to one embodiment, even without performing the aging step, a separator that simultaneously satisfies the physical properties as described above can be manufactured, and there is an advantage in that the time and material costs can be reduced in terms of the process.

[0101] The present disclosure can provide an electrochemical element including a separator according to one of the above-described embodiments. By including the separator as described above, the electrochemical element can have a reduced electrical resistance, significantly excellent life characteristics, and excellent thermal stability at high temperatures.

[0102] The electrochemical element may be any known energy storage device and is not particularly limited. As a non-limiting example, a lithium secondary battery may be mentioned. The lithium secondary battery is well-known, and its configuration is also well-known, so it will not be specifically described in the present disclosure.

[0103] A lithium secondary battery according to one embodiment may include the above-described separator between the positive electrode and the negative electrode. Here, the positive electrode and the negative electrode can be used without limitation as long as they are usually used in lithium secondary batteries.

[0104] The separator according to one embodiment is usually manufactured by a general manufacturing method in which an electrolyte is injected and completed by arranging and assembling the negative electrode, the separator, and the positive electrode when used in a battery, so it will not be described in more detail here.

[0105] Hereinafter, with reference to specific experimental examples, the embodiments of the present disclosure will be further described. The examples and comparative examples included in the experimental examples are illustrative of the present disclosure and do not limit the scope of the appended patent claims. It is obvious to those skilled in the art that various changes and modifications to the examples are possible within the scope of the present disclosure and the scope of the technical idea, and it is natural that such variations and modifications belong to the scope of the appended patent claims.

[0106] First, a method for measuring the physical properties of the separator and a method for evaluating the characteristics of the secondary battery will be described.

[0107] [Average thickness (μm) of separator and porous substrate] The average thickness of the separator was determined by the following method. After stacking 10 separators, the thickness was measured at 5 arbitrary points in the width direction using a thickness measuring instrument manufactured by Mitutoyo. Then, the average thickness of the 10 - layer separator was derived by dividing by 5, and the average thickness of the entire single separator was derived by dividing by 10.

[0108] The average thickness of the porous substrate was determined by the following method. Before forming the inorganic particle layer, only the porous substrate without the inorganic particle layer was stacked 10 - fold, and the thickness was measured at 5 arbitrary points in the width direction using a thickness measuring instrument manufactured by Mitutoyo. Then, the average thickness of the 10 - layer porous substrate was derived by dividing by 5, and the average thickness of the porous substrate was derived by dividing by 10. After forming the inorganic particle layer, the inorganic particle layer was detached using all known methods in the art without limitation, and after sufficient drying, the average thickness of the porous substrate from which the inorganic particle layer had been detached was derived by the above method.

[0109] [Coating amount (g / m 2 )] The coating amount was calculated by measuring the weight (g) per unit area (m 2 ) of the separator before and after coating. Specifically, first, the length and width of the substrate before coating were each cut to 10 cm, weighed, and multiplied by 100 to obtain m 2was converted to weight. After coating, the separator was also cut to the same size, weighed, multiplied by 100, and m 2 was converted to the weight of the substrate, and the conversion value of the substrate (g / m 2 ) was subtracted to obtain the coating amount of only the coating layer.

[0110] [Weight average molecular weight (g / mol)] The weight average molecular weight was measured using GPC (manufactured by Tosoh Corporation, EcoSEC HLC-8320GPC Refractive Index detector). The GPC column was Tskgel guard PWx, two TSKgel GMPWxl, and TSKgel G2500PWxl (7.8×300 mm). The eluent was 0.1M NaNO 3 aqueous solution. Polyethylene glycol was used as the standard, and the analysis was performed at 40°C with a flow rate of 1 mL / min.

[0111] [Gurley permeability (sec / 100cc)] Measured in accordance with ASTM D726 standard using a densometer manufactured by Toyoseiki Co., Ltd. The time required for 100 cc of air to pass through an area of 1 square inch of the separator was recorded in seconds and compared.

[0112] [Puncture strength (N / μm)] The puncture strength was measured by attaching a pin tip with a diameter of 1.0 mm and a curvature radius of 0.5 mm to a UTM (Universal Test Machine) 3345 manufactured by INSTRON and pressing the separator at a speed of 120 mm / min. Here, the puncture strength was calculated by dividing the load (N) when the separator breaks by the thickness (μm) of the separator.

[0113] [Tensile strength (kgf / cm 2 )] The tensile strength was measured according to ASTM D882 using a UTM (Universal Test Machine) 3345 manufactured by INSTRON. The separator was pulled in the transverse direction and the machine direction at a speed of 100 mm / min, and the strength was measured at the time when the separator broke.

[0114] [Thermal shrinkage rate (%)] The separator was cut into a square shape with a side length of 10 cm, and the transverse direction (TD) and the machine direction (MD) were marked. The sample was placed in the middle, and 5 sheets of paper were placed on the top and bottom of the sample, and the four sides of the paper were wrapped with tape. The test piece wrapped with paper was left in a hot air drying oven at 130 °C for 60 minutes. Then, the sample was taken out, the separator was measured with a camera, and the thermal shrinkage rate in the machine direction (MD) and the thermal shrinkage rate in the transverse direction (TD) were calculated using the following formula.

[0115] MD thermal shrinkage rate (%) = (Length of MD before heating - Length of MD after heating) / Length of MD before heating × 100 TD thermal shrinkage rate (%) = (Length of TD before heating - Length of TD after heating) / Length of TD before heating × 100

[0116] [Saturated moisture content (ppm)] The Karl Fischer method was used to measure the saturated moisture content of the separator. The measuring equipment used a Karl Fischer titrator manufactured by Metrohm, and the measuring conditions were a sample weight of 0.3 g of the separator, an oven temperature of 150 °C, and a measuring time of 600 seconds.

[0117] Specifically, the manufactured separator was left in a thermostatic and humidistatic chamber set at 40 °C and a relative humidity of 90% for 24 hours, and then the saturated moisture content was measured under the above conditions.

[0118] [Adhesive force] Cut the separator into a size of 50 mm in width and 50 mm in length, and arrange it so that the inorganic particle layer is on top. Place a black drawing paper (width 20 mm × length 150 mm × thickness 0.25 mm) with a coefficient of kinetic friction of 0.15 on it, and using a pressing device, after applying a predetermined pressure (200 g / cm 2 ), forcibly pull out the black drawing paper horizontally to check the degree of inorganic matter on the surface, and depending on the degree of adhesion, refer to the following grades and classify them as A / B / C / D / F.

[0119] A: No adhesion B: A small amount of inorganic matter adheres C~F represent the levels where both the binder and inorganic matter adhere, and the degree gets worse as it goes to F.

[0120] [Resistance characteristics of the battery] Each battery manufactured according to the examples and comparative examples was charged at 4.2 V with CCCV (Constant current-constant voltage) using a charge / discharge cycle device and then discharged. Specifically, each battery was charged at a constant current with a current of 0.5 C rate at 25°C until the voltage reached 4.2 V, and then charged at a constant voltage while maintaining 4.2 V until the current became 0.01 C. Next, during discharge, a cycle of discharging at a constant current of 0.5 C until the voltage reached 3.0 V was repeated 600 times. When the remaining capacity (State of charge; SoC) at the 600th cycle of charge / discharge was 60%, the DC-IR (Direct Current Internal Resistance) was measured during discharge by the J-Pulse method, and the resistance value was derived.

[0121] Here, based on the resistance value of Example 1, if the increase in the resistance of each battery manufactured according to the examples and comparative examples was less than 5%, it was denoted as "low", if it was 5% or more, it was denoted as "medium", and if it was 10% or more, it was denoted as "high".

[0122] [Manufacturing Example 1] After replacing the 1.0 L flask with nitrogen, 932 mmol of acrylamide and 89 mmol of 2-hydroxyethyl methacrylate as monomer components, and 700 g of distilled water were charged into the flask, and then the temperature was raised to 75 °C. Then, as a polymerization initiator, 0.789 mmol of ammonium persulfate was further charged into the flask, and the polymerization reaction of the mixture was carried out after sealing the flask. After proceeding with the polymerization reaction for 12 hours, the sealed flask was opened to the atmosphere to lower the temperature to room temperature, 1 M sodium hydroxide solution was added, and the pH was adjusted to 7 to produce an aqueous solution of polyacrylamide-based resin. Here, the weight average molecular weight of the produced polyacrylamide-based resin was 300,000 g / mol.

[0123] <Production Example 2> An aqueous solution of polyacrylamide-based resin was produced in the same manner as in Production Example 1, except that 1055 mmol of acrylamide was used alone as the monomer component. Here, the weight average molecular weight of the produced polyacrylamide-based resin was 280,000 g / mol.

[0124] <Example 1> Production of Coating Slurry With respect to the total weight of the solid content, as inorganic particles, boehmite (D10: 0.45 μm, D50: 0.71 μm, D90: 1.57 μm, BET specific surface area: 5 m 2 / g) was 96.5% by weight, and as a binder, 3.0% by weight of the polyacrylamide-based resin of Production Example 1 and 0.5% by weight of polyvinyl alcohol (saponification degree 88 mol%, Mw: 50,000 g / mol) were added to water, and then stirred to produce a coating slurry having a solid content concentration of 28% by weight.

[0125] Production of Separator As a porous substrate, a polyethylene porous film having an average thickness of 10 μm (porosity: 42%, Gurley permeability: 128 sec / 100 cc, MD tensile strength: 2,317 kgf / cm 2 , TD tensile strength: 2,514 kgf / cm 2It was used. After coating and applying the manufactured coating slurry on both sides of the porous substrate and then drying it, a separator was manufactured in which an inorganic particle layer was formed on both sides of the porous substrate with an average thickness of 1.35 μm. The physical properties of the separator are described in Table 1 below.

[0126] Manufacture of secondary battery As the positive electrode active material, 94 wt% of LiCoO 2 was added to 2.5 wt% of polyvinylidene fluoride as a binder, 3.5 wt% of carbon black as a conductive agent, and NMP (N-methyl-2-pyrrolidone) as a solvent, and stirred to produce a uniform positive electrode slurry. The produced slurry was coated, dried, and crimped on an aluminum foil with a thickness of 30 μm to produce a positive electrode with a total thickness of 150 μm. As the negative electrode active material, 95 wt% of artificial graphite, 3 wt% of an acrylic latex with a Tg of -52 °C as a binder, 2 wt% of CMC (carboxymethyl cellulose) as a thickener were added to water as a solvent, and stirred to produce a uniform negative electrode slurry. The produced negative electrode slurry was coated, dried, and crimped on a copper foil with a thickness of 20 μm to produce a negative electrode with a total thickness of 150 μm. The manufactured separator was stacked between the positive electrode and the negative electrode to assemble a pouch-type battery, and then the assembled battery for fusing the positive electrode, the negative electrode, and the separator together was heat-sealed with a heat press machine at 80 °C and 1 MPa. Then, 1 M of lithium hexafluorophosphate (LiPF 6 ) was dissolved in a solution containing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and after injecting the electrolyte, it was sealed to manufacture a secondary battery with a capacity of 2 Ah. The resistance characteristics of the secondary battery are summarized in Table 1 below.

[0127] <Example 2> As a binder, 3.5% by weight of the polyacrylamide-based resin of Production Example 1 was used instead of polyvinyl alcohol, and a separator and a secondary battery were produced in the same manner as in Example 1 except that a porous substrate pretreated by the following method was used. The characteristics of the separator and the secondary battery are shown in Table 1 below.

[0128] The pretreated porous substrate is a polyethylene porous film with an average thickness of 10 μm (porosity: 42%, Gurley permeability: 128 sec / 100 cc, MD tensile strength: 2,317 kgf / cm 2 , TD tensile strength: 2,514 kgf / cm 2 ), and was produced by subjecting both sides to corona discharge treatment. Here, the corona discharge treatment was carried out at a power density of 2 W / mm and a speed of 3 to 20 mpm (meter per minute).

[0129] <Example 3> As the components contained in the coating slurry, the same types were used, but the content was changed to 96.8% by weight of boehmite, 3.0% by weight of the polyacrylamide-based resin of Production Example 1, and 0.2% by weight of polyvinyl alcohol, and the porous substrate was changed to a polyethylene porous film with an average thickness of 10 μm (porosity: 42%, Gurley permeability: 109 sec / 100 cc, MD tensile strength: 2,055 kgf / cm 2 , TD tensile strength: 2,177 kgf / cm 2 ), and a separator and a secondary battery were produced in the same manner as in Example 1. The characteristics of the separator and the secondary battery are shown in Table 1 below.

[0130] <Example 4> As the porous substrate, a polyethylene porous film with an average thickness of 10 μm (porosity: 42%, Gurley permeability: 109 sec / 100 cc, MD tensile strength: 2,055 kgf / cm 2 , TD tensile strength: 2,177 kgf / cm 2A separator and a secondary battery were manufactured in the same manner as in Example 2, except that it was used after being subjected to corona discharge treatment. The characteristics of the separator and the secondary battery are shown in Table 1 below.

[0131] <Example 5> When manufacturing the coating slurry in Example 1, except that boehmite (D10: 0.56 μm, D50: 0.85 μm, D90: 1.93 μm, BET specific surface area: 4 m 2 / g) was used as the inorganic particles, a separator and a secondary battery were manufactured in the same manner as in Example 1. The characteristics of the separator and the secondary battery are shown in Table 1 below.

[0132] <Example 6> When manufacturing the coating slurry in Example 1, except that boehmite (D10: 0.38 μm, D50: 0.67 μm, D90: 1.52 μm, BET specific surface area: 6 m 2 / g) was used as the inorganic particles, a separator and a secondary battery were manufactured in the same manner as in Example 1. The characteristics of the separator and the secondary battery are shown in Table 1 below.

[0133] <Example 7> A separator and a secondary battery were manufactured in the same manner as in Example 1, except that the polyacrylamide-based resin of Production Example 2 was used instead of the polyacrylamide-based resin of Production Example 1. The characteristics of the separator and the secondary battery are shown in Table 1 below.

[0134] <Comparative Example 1> Instead of the coating slurry manufactured in Example 1, with respect to the total weight of the solid content, as the inorganic particles, boehmite (D10: 0.45 μm, D50: 0.71 μm, D90: 1.57 μm, BET specific surface area: 5 m 2Except that 93.0% by weight of (g) and 7.0% by weight of a water-based acrylic resin (glass transition temperature: -42°C) with a latex content of 20% by weight as a binder were added to water and stirred to produce a coating slurry with a solid content concentration of 28% by weight, the separator and secondary battery were manufactured in the same manner as in Example 1. The characteristics of the separator and secondary battery are described in Table 2 below.

[0135] <Comparative Example 2> When manufacturing the separator in Example 2, except that an inorganic particle layer with an average thickness of 2 μm was formed on both sides of a polyethylene porous film with an average thickness of 9 μm (porosity: 40%, Gurley permeability: 152 sec / 100 cc, MD tensile strength: 2,242 kgf / cm 2 , TD tensile strength: 1,864 kgf / cm 2 ), the separator and secondary battery were manufactured in the same manner as in Example 2. The characteristics of the separator and secondary battery are described in Table 2 below.

[0136] <Comparative Example 3> When manufacturing the coating slurry in Example 2, except that boehmite (D10: 0.16 μm, D50: 0.31 μm, D90: 0.75 μm, BET specific surface area: 20 m 2 / g) was used as the inorganic particles, the separator and secondary battery were manufactured in the same manner as in Example 2. The characteristics of the separator and secondary battery are described in Table 2 below.

[0137] <Comparative Example 4> When manufacturing the coating slurry in Example 2, except that boehmite (D10: 0.79 μm, D50: 1.64 μm, D90: 2.85 μm, BET specific surface area: 2.5 m 2 / g) was used as the inorganic particles, the separator and secondary battery were manufactured in the same manner as in Example 2. The characteristics of the separator and secondary battery are described in Table 2 below.

[0138] <Comparative Example 5> When manufacturing the coating slurry in Example 2, as the inorganic particles, boehmite (D10: 0.31 μm, D50: 0.58 μm, D90: 1.28 μm, BET specific surface area: 8 m 2 / g) was used, and the separator and the secondary battery were manufactured in the same manner as in Example 2 except for this. The characteristics of the separator and the secondary battery are shown in Table 2 below.

[0139]

Table 1

[0140]

Table 2

[0141] Referring to Table 1 and Table 2 above, it was confirmed that the separators of Examples 1 to 7 were excellent in heat resistance with a heat shrinkage rate of 5% or less even at a thin thickness, had no peeling in the adhesion test, and were also excellent in adhesion compared with the comparative examples. In addition, it was confirmed that the discharge resistance of the battery to which this was applied was low after 600 cycles.

[0142] In particular, Examples 1 to 6 were manufactured by further containing a hydroxy group-containing (meth) acrylate monomer other than the (meth) acrylamide-based monomer and using the resulting polyacrylamide-based resin as a binder. It was confirmed that they had better heat resistance than Example 7 in which the (meth) acrylamide-based monomer was used alone.

[0143] In addition, it was confirmed that Example 1 had better heat resistance than Example 2 by further containing polyvinyl alcohol as a binder, even though the porous substrate was not pretreated.

[0144] On the one hand, as a result of using an acrylic resin as a binder, it was confirmed that the heat resistance and adhesive strength of the separator of Comparative Example 1 significantly decreased at a thin thickness. Further, it was confirmed that the discharge resistance of the battery to which this was applied after 600 cycles was significantly higher than that of Example 1.

[0145] Further, since the separator of Comparative Example 2 has a t 1 / t 2 value of less than 0.75, it cannot satisfy the range of saturated moisture content to be achieved by the present disclosure. As a result, it was confirmed that the discharge resistance of the battery to which this was applied after 600 cycles was significantly higher than that of Example 1.

[0146] Further, as a result of using inorganic particles with a BET specific surface area of 20 m 2 / g, the separator of Comparative Example 3 cannot satisfy the range of saturated moisture content to be achieved by the present disclosure. As a result, it was confirmed that the discharge resistance of the battery to which this was applied after 600 cycles was higher than that of Example 1.

[0147] Further, as a result of using inorganic particles with a BET specific surface area of 2.5 m 2 / g, the separator of Comparative Example 4 cannot satisfy the range of saturated moisture content to be achieved by the present disclosure. As a result, it was confirmed that the heat resistance and adhesive strength at a thin thickness significantly decreased. Further, it was confirmed that the discharge resistance of the battery to which this was applied after 600 cycles was significantly higher than that of Example 1.

[0148] Further, as a result of using inorganic particles with a BET specific surface area of 8 m 2 / g, the separator of Comparative Example 5 cannot satisfy the range of saturated moisture content to be achieved by the present disclosure. As a result, it was confirmed that the discharge resistance of the battery to which this was applied after 600 cycles was higher than that of Example 1.

[0149] The above content is merely an exemplification of applying the principle of the present disclosure, and other configurations may be further included without departing from the scope of the present disclosure.

Claims

1. A porous substrate; an inorganic particle layer formed on at least one surface of the porous substrate and including a binder and inorganic particles; Gurley permeability is 10 to 250 sec / 100 cc, puncture strength is 0.3 N / μm or more, and tensile strength in the machine direction and width direction is 1500 kgf / cm ２ or more, and after standing at 130°C for 60 minutes, the heat shrinkage rate measured in the machine direction and width direction is 5% or less, and the saturated moisture content measured by the Karl Fischer method is 350 to 1000 ppm.

2. 2. The separator according to claim 1, wherein the Gurley permeability is 90 to 230 sec / 100 cc, and the saturated moisture content is 450 to 1000 ppm.

3. 2. The separator according to claim 1, wherein the average thickness of the porous substrate is 5 to 15 μm, and the ratio of the average thickness of the porous substrate to the average thickness of the separator is 0.7 or more.

4. The separator according to claim 1 , wherein the inorganic particle layer formed on the porous substrate has a total thickness of 3.2 μm or less.

5. The separator according to claim 1 , wherein the binder comprises a polyacrylamide resin.

6. The separator according to claim 5 , wherein the polyacrylamide resin is a copolymer containing units derived from a (meth)acrylamide monomer.

7. The separator according to claim 6 , wherein the polyacrylamide resin contains a structural unit derived from a (meth)acrylamide monomer and a structural unit derived from a (meth)acrylic monomer containing a hydroxy group.

8. The separator according to claim 5, wherein the polyacrylamide resin has a weight average molecular weight of 100,000 to 2,000,000 g / mol.

9. 6. The separator according to claim 5, wherein the binder further comprises one or more water-based polymers selected from the group consisting of polyvinyl alcohol, polyvinylidene fluoride, carboxymethyl cellulose, styrene butadiene rubber, polyacrylic acid, polyethylene glycol, polyacrylonitrile, polyvinylpyrrolidone, and copolymers thereof.

10. 10. The separator according to claim 9, wherein the content of the aqueous polymer is 0.1 to 30% by weight of the total content of the binder.

11. The inorganic particles have a BET specific surface area of ​​3 to 7 m ２ The separator of claim 1 , wherein the molecular weight is 1 / g.

12. The separator according to claim 1, wherein the inorganic particles have an average particle size (D50) of 0.5 to 1.5 μm.

13. The separator according to claim 1 , wherein the inorganic particles include at least one selected from the group consisting of metal hydroxides, metal oxides, metal nitrides, and metal carbides.

14. 2. The separator according to claim 1, wherein the inorganic particle layer has a weight ratio of inorganic particles to binder of 50:50 to 99.9:0.

1.

15. The inorganic particle layer has a density of 0.5 to 10 g / m ２ The separator of claim 1 formed from

16. An electrochemical element comprising the separator according to any one of claims 1 to 15.

17. The electrochemical device according to claim 16 , wherein the electrochemical device is a secondary battery.

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