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, more particularly, to a separator for an electrochemical device, and an electrochemical device comprising same, wherein the content of inorganic particles included in a porous polymeric substrate varies depending on the position to increase the capture effect of transition metal ions generated at a positive electrode and prevent by-products deposited at the interface of the positive electrode from clogging pores.

Description

Separator for electrochemical devices and electrochemical devices containing the same

[0001] The present invention claims the benefit of Korean Patent Application No. 10-2023-0052684 filed with the Korean Intellectual Property Office on April 21, 2023, 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 including the same, and more particularly, to a separator for an electrochemical device and an electrochemical device including the same, wherein the content of inorganic particles included in a porous polymer substrate is implemented differently depending on the location, thereby increasing the capture effect of transition metal ions generated at an anode and preventing byproducts deposited at the interface of the anode from clogging the pores.

[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 coating layer composition of the separator to secure adhesion between the electrode and the separator.

[0005] Meanwhile, in lithium-ion secondary batteries, transition metal ions within the positive electrode are eluted and pass through the separator to accumulate on the negative electrode, causing the battery to deteriorate due to the accumulated transition metal ions.

[0006] Furthermore, these transition metal ions and byproducts accumulate in the pores of the porous polymer substrate included in the separator, the pores of the coating layer, and the interface between the porous polymer substrate and the coating layer, which rapidly reduces the performance of the battery and causes degradation of the battery.

[0007] Ultimately, it was necessary to develop a battery that could prevent transition metal ions generated in the positive electrode from moving to the negative electrode and prevent pores from being blocked by the transition metal ions.

[0008] The technical problem to be achieved by the present invention is to provide a separator for an electrochemical device and an electrochemical device including the same, which implements pore size, porosity, and content of inorganic particles differently depending on the location of a porous polymer substrate, and allows the inorganic particles to absorb transition metal ions generated at an anode, thereby preventing pores from being blocked by the transition metal ions, and reducing byproducts that may be generated by battery operation.

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

[0010] One embodiment of the present invention provides a separator for an electrochemical device, comprising a porous polymer substrate including inorganic particles, a first portion adjacent to one surface of the porous polymer substrate and a second portion facing the first portion, a weight of the inorganic particles included in the first portion is greater than a weight of the inorganic particles included in the second portion, and the inorganic particles are capable of adsorbing transition metal ions.

[0011] According to one embodiment of the present invention, the inorganic particles may be one selected from the group consisting of zeolite, silica gel, carbon fiber, porous carbon, porous metal oxide, metal-organic framework (MOF), and combinations thereof.

[0012] According to one embodiment of the present invention, the inorganic particles included in the first part and the inorganic particles included in the second part may be the same or different.

[0013] According to one embodiment of the present invention, the porous polymer substrate may be a polyolefin resin.

[0014] According to one embodiment of the present invention, the size of the pores included in the first part may be larger than the size of the pores included in the second part.

[0015] According to one embodiment of the present invention, the size of the pores included in the first portion may be 20 ㎛ or more and 100 ㎛ or less, and the size of the pores included in the second portion may be 20 ㎛ or more and 100 ㎛ or less.

[0016] According to one embodiment of the present invention, the porosity of the first portion may be greater than the porosity included in the second portion.

[0017] According to one embodiment of the present invention, the porosity of the first part may be 50% by volume or more and 70% by volume or less, and the porosity of the second part may be 40% by volume or more and 50% by volume or less.

[0018] According to one embodiment of the present invention, the thickness of the first part may be equal to or smaller than the thickness of the second part.

[0019] According to one embodiment of the present invention, the first part may be provided to be adjacent to the anode.

[0020] According to one embodiment of the present invention, a portion of the surface of the inorganic particles may be included to protrude outward from the porous polymer substrate.

[0021] According to one embodiment of the present invention, the thickness of the separator for the electrochemical device may be 9 ㎛ or less.

[0022] One embodiment of the present invention provides an electrochemical device comprising a positive electrode; a negative electrode; and a separator, wherein the separator is interposed between the positive electrode and the negative electrode, and is a separator for an electrochemical device.

[0023] According to one embodiment of the present invention, the first part of the separator may be arranged to face the anode, and the second part of the separator may be arranged to face the cathode.

[0024] A separator for an electrochemical device according to one embodiment of the present invention can capture transition metal ions generated at the anode and prevent them from accumulating at the cathode.

[0025] A separator for an electrochemical device according to one embodiment of the present invention can prevent pores from being blocked by transition metal ions generated at an anode and prevent deterioration of a battery.

[0026] A separator for an electrochemical device according to one embodiment of the present invention can secure insulation by including small-sized pores.

[0027] An electrochemical device according to one embodiment of the present invention can improve the performance of a battery and extend the life of the battery.

[0028] Figure 1 is a schematic diagram of a separator for an electrochemical device according to one embodiment of the present invention.

[0029] Figure 2 is a schematic diagram of a separator for an electrochemical device according to one embodiment of the present invention.

[0030] Figure 3 is a schematic diagram of an electrochemical device according to one embodiment of the present invention.

[0031] In this specification, when a part is said to "include" a certain component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0032] In this specification, “A and / or B” means “A and B, or A or B.”

[0033] In this specification, when it is said that a component is “provided on”, this does not exclude that other components are disposed in between, unless otherwise specifically stated, but rather means that other components are further disposed.

[0034] In this specification, the “characteristic of having pores” means that the object includes a plurality of pores and the pores are interconnected to each other, thereby allowing gaseous and / or liquid fluids to pass from one side of the object to the other side.

[0035] 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.

[0036] Hereinafter, the present invention will be described in more detail.

[0037] One embodiment of the present invention provides a separator for an electrochemical device, comprising a porous polymer substrate including inorganic particles, a first portion adjacent to one surface of the porous polymer substrate and a second portion facing the first portion, a weight of the inorganic particles included in the first portion is greater than a weight of the inorganic particles included in the second portion, and the inorganic particles are capable of adsorbing transition metal ions.

[0038] A separator for an electrochemical device according to one embodiment of the present invention can capture transition metal ions generated at the anode and prevent them from accumulating at the cathode. Furthermore, a separator for an electrochemical device according to one embodiment of the present invention can prevent pores from being blocked by transition metal ions generated at the anode, thereby preventing battery deterioration. In addition, a separator for an electrochemical device according to one embodiment of the present invention can secure insulation by including small-sized pores.

[0039] FIG. 1 is a schematic diagram of a separator for an electrochemical device according to one embodiment of the present invention. Referring to FIG. 1, the separator for an electrochemical device according to one embodiment of the present invention will be described in detail.

[0040] According to one embodiment of the present invention, the separator (100) for an electrochemical device includes a porous polymer substrate (110). As described above, the separator (100) for an electrochemical device includes the porous polymer substrate (110), thereby allowing lithium ions to pass through while blocking electrical contact, and implementing a shutdown function at an appropriate temperature.

[0041] According to one embodiment of the present invention, the porous polymer substrate may be a polyolefin-based resin. Specifically, the porous polymer substrate (110) may be manufactured using a polyolefin-based resin as a base resin. Examples of the polyolefin-based resin include polyethylene, polypropylene, polypentene, etc., and the porous polymer substrate may include one or more of these. A porous membrane manufactured using such a polyolefin-based resin as a base resin, i.e., having a large number of pores, is advantageous in terms of imparting a shutdown function at an appropriate temperature.

[0042] 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.

[0043] In this specification, “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.

[0044] - Column: PL Olexis (Polymer Laboratories)

[0045] - Solvent: TCB (Trichlorobenzene)

[0046] - Flow rate: 1.0 ml / min

[0047] - Sample concentration: 1.0 mg / ml

[0048] - Injection volume: 200 ㎕

[0049] - Column temperature: 160 ℃

[0050] - Detector: Agilent High Temperature RI detector

[0051] - Standard: Polystyrene (corrected with a cubic function)

[0052] According to one embodiment of the present invention, the porous polymer substrate (110) may be manufactured by a method (wet method) of mixing a polyolefin resin with a plasticizer (diluent) and inorganic particles at a high temperature to form a single phase, separating the polyolefin resin and the plasticizer during a cooling process, extracting the plasticizer to form pores, and then stretching and heat-setting the mixture.

[0053] According to one embodiment of the present invention, the porous polymer substrate (110) may be manufactured by a method (wet method) in which a first part of the porous polymer substrate is mixed with a polyolefin-based resin at a high temperature with a plasticizer (diluent) and inorganic particles to form a single phase, the polyolefin-based resin 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, and a second part of the porous polymer substrate is manufactured by a method (wet method) in which a polyolefin-based resin is mixed with a plasticizer (diluent) and inorganic particles at a high temperature to form a single phase, the polyolefin-based resin 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, and then the first part and the second part are laminated with heat.

[0054] According to one embodiment of the present invention, the average pore size and the maximum pore size of the electrochemical device separator (100) can be easily manufactured by a person skilled in the art to conform to the scope of the present invention by controlling the mixing ratio of the plasticizer, the stretching ratio, and the heat-setting treatment temperature.

[0055] In this specification, “pore size” can be calculated from the pore size distribution measured using the Capillary Flow Porometer method. For example, first, the membrane to be measured is wetted with a wetting agent such as a Galwick solution, and then the air pressure on one side of the substrate is gradually increased. When the applied air pressure becomes greater than the capillary attraction of the wetting agent present in the pores, the wetting agent blocking the pores is pushed out, and the pore size and distribution are measured through the pressure and flow rate at the moment of being pushed out, from which the average pore size and maximum size can be determined.

[0056] According to one embodiment of the present invention, the electrochemical device separator (100) includes a porous polymer substrate (110) containing inorganic particles. As described above, by the electrochemical device separator including the porous polymer substrate containing inorganic particles, the capture efficiency of transition metal ions generated at the anode can be improved, and the transition metal ions can be prevented from passing through the pores and accumulating at the cathode or at the interface between the separator and the anode.

[0057] According to one embodiment of the present invention, it includes a first part (111) adjacent to one side of the porous polymer substrate and a second part (113) facing the first part (111). Specifically, it may include a first part including the one side and a second part including the other side on one side and the other side of the porous polymer substrate. That is, it may include a first part including one side of the porous substrate and a second part including the other side of the porous substrate based on the center line of the porous polymer substrate, and the first part and the second part may be in contact with each other or further include another part between the first part and the second part. As described above, by including the first part adjacent to one side of the porous polymer substrate and the second part facing the first part, the physical properties or chemical properties can be implemented differently depending on the electrodes adjacent to the one side and the other side of the porous polymer substrate, thereby improving the performance of the battery.

[0058] According to one embodiment of the present invention, the weight of the inorganic particles included in the first portion is greater than the weight of the inorganic particles included in the second portion. Specifically, the content of the inorganic particles in the first portion may be greater than the content of the inorganic particles in the second portion. As described above, by implementing that the weight of the inorganic particles included in the first portion is greater than the weight of the inorganic particles included in the second portion, the transition metal ions generated at the anode can be easily adsorbed, thereby improving the capture efficiency.

[0059] According to one embodiment of the present invention, the particle size of the inorganic particles included in the first portion may be larger than the particle size of the inorganic particles included in the second portion. As described above, by implementing the particle size of the inorganic particles included in the first portion to be larger than the particle size of the inorganic particles included in the second portion, the pore size and / or porosity of the first portion can be implemented to be larger than the pore size and / or porosity of the second portion.

[0060] According to one embodiment of the present invention, the inorganic particles are capable of adsorbing transition metal ions. Specifically, the transition metal ions may be transition metal ions generated at the anode. As described above, by selecting the inorganic particles capable of adsorbing transition metal ions, the transition metal ions generated at the anode can be adsorbed and captured, thereby minimizing the accumulation of transition metal ions at the cathode.

[0061] According to one embodiment of the present invention, the inorganic particles may be one selected from the group consisting of zeolite, silica gel, carbon fiber, porous carbon, porous metal oxide, metal-organic framework (MOF), and combinations thereof. By selecting the inorganic particles from the above, transition metal ions generated at the positive electrode can be adsorbed and captured, thereby minimizing transition metal ions accumulated at the negative electrode.

[0062] According to one embodiment of the present invention, the porous carbon may be one selected from the group consisting of activated carbon, activated carbon fiber, carbon nanotube, and combinations thereof.

[0063] According to one embodiment of the present invention, the porous metal oxide may be one selected from the group consisting of porous SiO2, porous Al2O3, porous AlOOH, porous Al(OH)3, and combinations thereof.

[0064] According to one embodiment of the present invention, the organometallic complex (MOF) may be one selected from the group consisting of MOF-808, UiO-66-NH2, UiO-66, UiO-66-COOH, UiO-66-F4, UiO-67, MIL-101, MIL-125, MIL-53, MIL-100, MIL-53(Al) MOF, ZIF-8 MOF, HKUST-1 MOF, and combinations thereof.

[0065] According to one embodiment of the present invention, the inorganic particles included in the first portion and the inorganic particles included in the second portion may be the same or different. As described above, by implementing the inorganic particles included in the first portion and the inorganic particles included in the second portion as the same or different, the capture efficiency of transition metal ions can be implemented differently depending on the location, and the porosity and pore size can be adjusted differently depending on the location.

[0066] According to one embodiment of the present invention, the size of the pores included in the first portion may be larger than the size of the pores included in the second portion. As described above, by adjusting the size of the pores included in the first portion to be larger than the size of the pores included in the second portion, the pores are prevented from being blocked by transition metal ions generated from the anode, and the size of the pores in a portion where there is no risk of pore blockage is made small, thereby ensuring insulation, and thereby reducing the thickness of the separator.

[0067] According to one embodiment of the present invention, the size of the pores included in the first portion may be 20 ㎛ or more and 100 ㎛ or less. Specifically, the size of the pores included in the first portion may be 25 ㎛ or more and 95 ㎛ or less, 30 ㎛ or more and 90 ㎛ or less, 35 ㎛ or more and 85 ㎛ or less, 40 ㎛ or more and 80 ㎛ or less, 45 ㎛ or more and 75 ㎛ or less, 50 ㎛ or more and 70 ㎛ or less, or 55 ㎛ or more and 65 ㎛ or less. By controlling the size of the pores included in the first portion within the above-described range, it is possible to prevent the pores from being blocked by transition metal ions generated from the anode.

[0068] According to one embodiment of the present invention, the size of the pores included in the second portion may be 20 ㎛ or more and 100 ㎛ or less. Specifically, the size of the pores included in the second portion may be 25 ㎛ or more and 95 ㎛ or less, 30 ㎛ or more and 90 ㎛ or less, 35 ㎛ or more and 85 ㎛ or less, 40 ㎛ or more and 80 ㎛ or less, 45 ㎛ or more and 75 ㎛ or less, 50 ㎛ or more and 70 ㎛ or less, or 55 ㎛ or more and 65 ㎛ or less. By adjusting the size of the pores included in the second portion within the above-described range, the size of the pores in a portion where there is no risk of the pores being blocked can be made small, thereby ensuring insulation, and thereby reducing the thickness of the separator.

[0069] According to one embodiment of the present invention, the porosity of the first portion may be greater than the porosity included in the second portion. As described above, by implementing the porosity of the first portion to be greater than the porosity included in the second portion, the pores are prevented from being blocked by transition metal ions generated from the anode, and the porosity of the portion where the pores are not at risk of being blocked is implemented to be small, thereby ensuring insulation, and thereby reducing the thickness of the separator.

[0070] According to one embodiment of the present invention, the porosity of the first portion may be 50 vol% or more and 70 vol% or less. Specifically, the porosity of the first portion may be 51 vol% or more and 69 vol%, 52 vol% or more and 68 vol%, 53 vol% or more and 67 vol%, 54 vol% or more and 66 vol%, 55 vol% or more and 65 vol%, 56 vol% or more and 64 vol%, 57 vol% or more and 63 vol%, 58 vol% or more and 62 vol%, or 59 vol% or more and 61 vol%. By controlling the porosity of the first portion within the above-described range, it is possible to prevent the pores from being blocked by transition metal ions generated from the anode.

[0071] According to one embodiment of the present invention, the porosity of the second portion may be 40 vol% or more and 50 vol% or less. Specifically, the porosity of the second portion may be 41 vol% or more and 49 vol%, 42 vol% or more and 48 vol%, 43 vol% or more and 47 vol%, or 44 vol% or more and 46 vol%. By controlling the porosity of the second portion within the above-described range, the size of the pores in a portion where there is no risk of the pores being blocked can be made small, thereby ensuring insulation, and thereby reducing the thickness of the separator.

[0072] In this specification, “porosity” means the ratio of the volume occupied by pores to the total volume, and uses vol% as its unit, and can be used interchangeably with terms such as porosity, porosity, etc. In the present invention, the measurement of the porosity is not particularly limited, and according to an embodiment of the present invention, it can be measured by, for example, the BET (Brunauer-Emmett-Teller) measurement method using nitrogen gas or the mercury penetration method (Hg porosimeter). Or, in an embodiment of the present invention, the true density of the electrode active material layer can be calculated from the density (apparent density) of the obtained electrode (electrode active material layer) and the composition ratio of materials included in the electrode (electrode active material layer) and the density of each component, and the porosity of the electrode active material layer can be calculated from the difference between the apparent density and the true density.

[0073] According to one embodiment of the present invention, the thickness of the first portion may be equal to or smaller than the thickness of the second portion. The thickness of each portion may refer to the length of a straight line perpendicular to one surface of the porous polymer substrate in the total length passing through the porous polymer substrate. Specifically, the thickness of the first portion may be greater than 0% and less than or equal to 50% of the total thickness of the porous polymer substrate. As described above, by implementing the thickness of the first portion to be equal to or smaller than the thickness of the second portion, the pores can be prevented from being blocked by transition metal ions generated from the anode, and the insulation of the separator can be secured.

[0074] According to one embodiment of the present invention, the first portion may be provided adjacent to the positive electrode. As described above, by providing the first portion adjacent to the positive electrode, the transition metal ions and / or byproducts generated from the positive electrode are prevented from accumulating on the porous polymer substrate, the coating layer described below, and the interface between the coating layer and the porous polymer substrate, thereby improving the capture efficiency of the transition metal ions and preventing the battery from deteriorating. Furthermore, the pores of the first portion are prevented from being blocked by the transition metal ions generated from the positive electrode, thereby improving the lifespan of the battery.

[0075] According to one embodiment of the present invention, a portion of the surface of the inorganic particle may be included so as to protrude outward from the porous polymer substrate. Specifically, this may mean that the inorganic particle is not sealed by the porous polymer substrate, and a portion of the inorganic particle is exposed to the pores of the porous polymer substrate or the surface of the porous polymer substrate. As described above, by including a portion of the surface of the inorganic particle so as to protrude outward from the porous polymer substrate, the efficiency of capturing transition metal ions by the inorganic particle can be improved.

[0076] According to one embodiment of the present invention, the thickness of the separator for the electrochemical device may be 9 ㎛ or less. Specifically, the thickness of the separator for the electrochemical device may be greater than 0 ㎛ and less than or equal to 9 ㎛, greater than or equal to 1 ㎛ and less than or equal to 8 ㎛, greater than or equal to 2 ㎛ and less than or equal to 7 ㎛, greater than or equal to 3 ㎛ and less than or equal to 6 ㎛, or greater than or equal to 4 ㎛ and less than or equal to 5 ㎛. By controlling the thickness of the separator for the electrochemical device within the above-described range, the energy density of the electrochemical device can be improved.

[0077] In one embodiment of the present invention, the thickness of the porous polymer substrate, the coating layer, and / or the adhesive 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.

[0078] According to one embodiment of the present invention, the electrochemical device separator (100) may include a coating layer (130) provided on at least one surface of the porous polymer substrate (110). Specifically, the electrochemical device separator (100) may include a coating layer (130) provided on one surface of the porous polymer substrate (110) or may include a coating layer (130) provided on both surfaces of the porous polymer substrate (110). As described above, by the electrochemical device separator (100) including the 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.

[0079] According to one embodiment of the present invention, the electrochemical device separator (100) may include a coating layer (130) including a first polymer binder (131, not shown) and inorganic particles (133, not shown). As described above, since the coating layer (130) includes the first polymer binder (131) and the inorganic particles (133), the heat resistance of the separator is improved, the mechanical properties are improved, the shrinkage of the separator at high temperatures is prevented, resulting in an electrical short circuit of the electrode, and pores can be formed inside the coating layer.

[0080] According to one embodiment of the present invention, the coating layer (130) may be formed by inorganic particles (133) being bound by a first polymer binder (131) and integrated within the side. The pores within the coating layer (130) may be derived from an interstitial volume, which is an empty space between the inorganic particles (133).

[0081] According to one embodiment of the present invention, the coating layer includes a plurality of pores. That is, the coating layer may be porous.

[0082] According to one embodiment of the present invention, the first polymer binder (131) may be an acrylic binder, a polyvinylidene binder, or a combination thereof. By selecting the first polymer binder (131) from the above-described binders, as described above, the heat resistance of the coating layer can be improved, and the bonding strength of the inorganic particles within the coating layer can be improved.

[0083] According to one embodiment of the present invention, the first polymer binder (131) may be an acrylic binder. This can maintain the porosity of the separator, improve the adhesive strength between the electrode and the separator during the lamination process of the battery, thereby improving the ease of battery manufacturing, and stably implementing the stacking process.

[0084] According to one embodiment of the present invention, the acrylic binder is a polymer containing a carboxylic acid ester as a repeating unit, and may preferably be a (meth)acrylic acid ester or an acrylic-styrene copolymer.

[0085] According to one embodiment of the present invention, the (meth)acrylic acid ester is methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, n-amyl (meth)acrylate, i-amyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, hydroxymethyl (meth)acrylate, hydroxyethyl (meth)acrylate, ethylene glycol (meth)acrylate, di(meth)acrylate, propylene glycol (meth)acrylate, Examples thereof include trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, allyl (meth)acrylate, and ethylene di(meth)acrylate, and the like may be at least one selected from these. Among these, at least one selected from methyl (meth)acrylate, ethyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate is preferable, and methyl (meth)acrylate is particularly preferable.

[0086] According to one embodiment of the present invention, the acrylic-styrene copolymer may include an acrylic binder, and the acrylic binder may be a polyacrylate. For example, the binder may be at least one selected from the group consisting of styrenebutadiene rubber, nitrile-butadiene rubber, acrylonitrile-butadiene rubber, acrylonitrile-butadiene-styrene rubber, and acrylate polymers, and more specifically, may be a copolymer including acrylate.

[0087] According to one embodiment of the present invention, the polyvinylidene-based binder included in the first polymer binder (131) may be a polyvinylidene fluoride (PVdF, polyvinylidene difluoride)-based binder. As described above, by selecting the polyvinylidene-based binder as a polyvinylidene fluoride-based binder, the resistance of the separator can be reduced.

[0088] According to one embodiment of the present invention, the polyvinylidene-based binder included in the first polymer binder (131) may be a polyvinylidene fluoride (PVdF, polyvinylidene difluoride)-based binder. As described above, by selecting the polyvinylidene-based binder as a polyvinylidene fluoride-based binder, the resistance of the separator can be reduced.

[0089] According to one embodiment of the present invention, the polyvinylidene-based binder may be a copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF-co-HFP, Poly(vinylidene fluoride-co-hexafluoropropylene)). As described above, by selecting the polyvinylidene-based binder as a copolymer of polyvinylidene fluoride and hexafluoropropylene, the dissolution of the polymer binder by the electrolyte can be minimized.

[0090] According to one embodiment of the present invention, the polyvinylidene-based binder included in the first polymer binder (131) may have a hexafluoropropylene content of 10 wt% or more. Specifically, the polyvinylidene-based binder included in the first polymer binder (131) may have a hexafluoropropylene content of 10 wt% or more and 80 wt% or less, 15 wt% or more and 75 wt% or less, 20 wt% or more and 70 wt% or less, 25 wt% or more and 65 wt% or less, 30 wt% or more and 60 wt% or less, 35 wt% or more and 55 wt% or less, or 40 wt% or more and 50 wt% or less. By controlling the content of hexafluoropropylene included in the polyvinylidene-based binder in the first polymer binder (131) within the above-described range, the resistance of the separator can be reduced.

[0091] According to one embodiment of the present invention, the first polymer binder (131) may be a hybrid binder particle including an acrylic binder and a polyvinylidene binder. As described above, by selecting the first polymer binder (133) as a hybrid binder particle including an acrylic binder and a polyvinylidene binder, the adhesive strength with the electrode can be improved.

[0092] According to one embodiment of the present invention, the first polymer binder (131) may be in particle or liquid form. By selecting the first polymer binder (131) from the above-described ones, the porosity and air permeability of the coating layer can be controlled, the pore size of the coating layer can be controlled, and the mechanical properties of the coating layer can be improved.

[0093] According to one embodiment of the present invention, the content of the first polymer binder (131) may be 30 parts by weight or less with respect to 100 parts by weight of the coating layer. Specifically, the content of the first polymer binder (131) may be more than 0 parts by weight and less than or equal to 30 parts by weight, 5 parts by weight or more and 25 parts by weight or less, 10 parts by weight or more and 20 parts by weight or less, 12 parts by weight or more and 18 parts by weight or less, or 13 parts by weight or more and 16 parts by weight or less with respect to 100 parts by weight of the coating layer (130). By controlling the content of the first polymer binder (131) within the above-described range, the mechanical properties of the coating layer (130) can be improved, the porosity of the coating layer can be maintained, and heat resistance can be improved.

[0094] According to one embodiment of the present invention, the content of the inorganic particles (133) may be 70 parts by weight or more with respect to 100 parts by weight of the coating layer (130). Specifically, the content of the inorganic particles (133) may be more than 70 parts by weight and less than 100 parts by weight, 75 parts by weight or more and 95 parts by weight or less, 80 parts by weight or more and 90 parts by weight or less, 82 parts by weight or more and 88 parts by weight or less, or 84 parts by weight or more and 86 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 (133) within the above-described range, the heat resistance and mechanical properties of the separator can be improved.

[0095] According to one embodiment of the present invention, the inorganic particles (133) that can be used in the coating layer (130) are not particularly limited as long as they are electrochemically stable. That is, the inorganic particles that can be used in one embodiment of the present invention are those that can be used in the operating voltage range of the applied electrochemical device (e.g., Li / Li). + There are no particular limitations as long as no oxidation and / or reduction reaction occurs at a voltage of 0 V to 5 V (as a reference).

[0096] According to one embodiment of the present invention, non-limiting examples of the inorganic particles (133) include BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT, 0 <x<1, 0<y<1), Pb(Mg 1 / 3 Nb 2 / 3 )O3-PbTiO3(PMN-PT), hafnia (HfO2), SrTiO3, SnO2, CeO2, MgO, Mg(OH)2, NiO, CaO, ZnO, ZrO2, SiO2, Y2O3, Al2O3, SiC, Al(OH)3, TiO2, aluminum peroxide, zinc tin hydroxide (ZnSn(OH)6), tin-zinc oxide (Zn2SnO4, ZnSnO3), antimony trioxide (Sb2O3), antimony tetroxide (Sb2O4), antimony pentoxide (Sb2O5), zeolite compounds, etc., and one or more of these may be included.

[0097] According to one embodiment of the present invention, the zeolite compound may be one selected from the group consisting of zeolite A, zeolite X, zeolite Y, zeolite L, ZSM-5, beta-zeolite, ZSM-8, ZSM-11, and combinations thereof. The zeolite compound may have a high specific surface area. By selecting the zeolite compound from the above, the ability to adsorb gases and transition metals may be improved.

[0098] According to one embodiment of the present invention, the average diameter (D) of the inorganic particles (133) 50 ) has no special limitations, but in order to form a coating layer of uniform thickness and have an appropriate porosity, it is preferably in the range of 0.3 ㎛ to 1 ㎛. Specifically, when it is less than 0.3 ㎛, the dispersibility of inorganic particles in the slurry prepared for manufacturing the coating layer may be reduced, and when it exceeds 1 ㎛, the thickness of the formed coating layer may increase.

[0099] In this specification, "D50 particle size" means the particle size at the 50% point of the cumulative distribution of particle numbers according to particle size. The particle size can be measured using a laser diffraction method. Specifically, after the powder to be measured is dispersed in a dispersion medium, it is introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500), and when the particles pass through the laser beam, the difference in the diffraction pattern according to the particle size is measured to calculate the particle size distribution. By calculating the particle diameter at the point where the cumulative distribution of particle numbers according to particle size in the measuring device becomes 50%, the D50 particle size can be measured.

[0100] Figure 2 is a schematic diagram of a separator for an electrochemical device according to one embodiment of the present invention. Referring to Figure 2, the separator for an electrochemical device according to one embodiment of the present invention will be described in detail.

[0101] According to one embodiment of the present invention, the electrochemical device separator (100) may include an adhesive layer (150) provided on the coating layer (130). Specifically, the electrochemical device separator (100) may include an adhesive layer (150) provided on the coating layer (130) and including a second polymer binder (151, not shown). As described above, since the electrochemical device separator (100) includes an adhesive layer (150) provided on the coating layer (130), adhesion between the electrode and the separator can be secured during the lamination process of the separator with the electrode.

[0102] According to one embodiment of the present invention, the thickness of the coating layer (130) on one side of the porous polymer substrate (110) may be 2.0 ㎛ or less. Specifically, the thickness of the coating layer (130) may be greater than 0 ㎛ and less than or equal to 2.0 ㎛, greater than or equal to 0.1 ㎛ and less than or equal to 1.9 ㎛, greater than or equal to 0.2 ㎛ and less than or equal to 1.8 ㎛, greater than or equal to 0.3 ㎛ and less than or equal to 1.7 ㎛, greater than or equal to 0.4 ㎛ and less than or equal to 1.6 ㎛, greater than or equal to 0.5 ㎛ and less than or equal to 1.5 ㎛, greater than or equal to 0.6 ㎛ and less than or equal to 1.4 ㎛, greater than or equal to 0.7 ㎛ and less than or equal to 1.3 ㎛, greater than or equal to 0.8 ㎛ and less than or equal to 1.2 ㎛, or greater than or equal to 0.9 ㎛ and less than or equal to 1.1 ㎛. By controlling the thickness of the coating layer (130) within the above-described range, the heat resistance of the separator can be improved and the energy density of the separator can be increased.

[0103] According to one embodiment of the present invention, the second polymer binder (151) may be an acrylic binder, a polyvinylidene binder, or a combination thereof. By selecting the second polymer binder (151) from the above-described binders, as described above, the adhesiveness of the adhesive layer can be improved.

[0104] According to one embodiment of the present invention, the second polymer binder (151) may be an acrylic binder. This can maintain the porosity of the separator, improve the adhesive strength between the electrode and the separator during the lamination process of the battery, thereby improving the ease of battery manufacturing, and stably implementing the stacking process.

[0105] According to one embodiment of the present invention, the acrylic binder is a polymer containing a carboxylic acid ester as a repeating unit, and may preferably be a (meth)acrylic acid ester or an acrylic-styrene copolymer.

[0106] According to one embodiment of the present invention, the (meth)acrylic acid ester is methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, n-amyl (meth)acrylate, i-amyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, hydroxymethyl (meth)acrylate, hydroxyethyl (meth)acrylate, ethylene glycol (meth)acrylate, di(meth)acrylate, propylene glycol (meth)acrylate, Examples thereof include trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, allyl (meth)acrylate, and ethylene di(meth)acrylate, and the like may be at least one selected from these. Among these, at least one selected from methyl (meth)acrylate, ethyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate is preferable, and methyl (meth)acrylate is particularly preferable.

[0107] According to one embodiment of the present invention, the acrylic-styrene copolymer may include an acrylic binder, and the acrylic binder may be a polyacrylate. For example, the binder may be at least one selected from the group consisting of styrenebutadiene rubber, nitrile-butadiene rubber, acrylonitrile-butadiene rubber, acrylonitrile-butadiene-styrene rubber, and acrylate polymers, and more specifically, may be a copolymer including acrylate.

[0108] According to one embodiment of the present invention, the polyvinylidene-based binder included in the second polymer binder (151) may be a polyvinylidene fluoride (PVdF, polyvinylidene difluoride)-based binder. As described above, by selecting the polyvinylidene-based binder as a polyvinylidene fluoride-based binder, the resistance of the separator can be reduced.

[0109] According to one embodiment of the present invention, the polyvinylidene-based binder included in the second polymer binder (151) may be a polyvinylidene fluoride (PVdF, polyvinylidene difluoride)-based binder. As described above, by selecting the polyvinylidene-based binder as a polyvinylidene fluoride-based binder, the resistance of the separator can be reduced.

[0110] According to one embodiment of the present invention, the polyvinylidene-based binder may be a copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF-co-HFP, Poly(vinylidene fluoride-co-hexafluoropropylene)). As described above, by selecting the polyvinylidene-based binder as a copolymer of polyvinylidene fluoride and hexafluoropropylene, the dissolution of the polymer binder by the electrolyte can be minimized.

[0111] According to one embodiment of the present invention, the polyvinylidene-based binder included in the second polymer binder (151) may have a hexafluoropropylene content of 10 wt% or more. Specifically, the polyvinylidene-based binder included in the first polymer binder (131) may have a hexafluoropropylene content of 10 wt% or more and 80 wt% or less, 15 wt% or more and 75 wt% or less, 20 wt% or more and 70 wt% or less, 25 wt% or more and 65 wt% or less, 30 wt% or more and 60 wt% or less, 35 wt% or more and 55 wt% or less, or 40 wt% or more and 50 wt% or less. By controlling the content of hexafluoropropylene included in the polyvinylidene-based binder in the first polymer binder (131) within the above-described range, the resistance of the separator can be reduced. The content of the above hexafluoropropylene (HFP) monomer is 1 H-NMR and / or 19 It can be measured by F-NMR.

[0112] According to one embodiment of the present invention, the second polymer binder (151) may be a hybrid binder particle including an acrylic binder and a polyvinylidene binder. As described above, by selecting the second polymer binder (151) as a hybrid binder particle including an acrylic binder and a polyvinylidene binder, the adhesive strength with the electrode can be improved.

[0113] According to one embodiment of the present invention, the second polymer binder (151) may be in particle or liquid form. By selecting the second polymer binder (151) from the above-described ones, the porosity and air permeability of the adhesive layer can be controlled, the pore size of the adhesive layer can be controlled, and the adhesive strength of the adhesive layer can be improved.

[0114] According to one embodiment of the present invention, the particle size (D50) of the second polymer binder is preferably in the range of 0.3 ㎛ or more and 1 ㎛ or less. Specifically, when it is less than 0.3 ㎛, the dispersibility of the second polymer binder in the slurry prepared for producing the adhesive layer may be reduced, and when it exceeds 1 ㎛, the thickness of the formed adhesive layer may increase.

[0115] According to one embodiment of the present invention, the thickness of the adhesive layer (150) may be 2.0 ㎛ or less. Specifically, the thickness of the adhesive layer (150) may be more than 0 ㎛ and less than 2.0 ㎛, 0.1 ㎛ or more and 1.9 ㎛ or less, 0.2 ㎛ or more and 1.8 ㎛ or less, 0.3 ㎛ or more and 1.7 ㎛ or less, 0.4 ㎛ or more and 1.6 ㎛ or less, 0.5 ㎛ or more and 1.5 ㎛ or less, 0.6 ㎛ or more and 1.4 ㎛ or less, 0.7 ㎛ or more and 1.3 ㎛ or less, 0.8 ㎛ or more and 1.2 ㎛ or less, or 0.9 ㎛ or more and 1.1 ㎛ or less. By controlling the thickness of the adhesive layer (150) within the above-described range, the adhesion of the separator to the electrode can be improved, and the energy density of the separator can be increased.

[0116] In this specification, “membrane permeability” may be measured using EG01-55-1MR equipment from Asahi seico.

[0117]

[0118] One embodiment of the present invention provides a method for manufacturing a separator for an electrochemical device, comprising the steps of: kneading a mixture containing a polyolefin resin, inorganic particles, and a plasticizer at a high temperature; combining the kneaded mixture; cooling the extruded mixture to phase-separate the plasticizer; extracting the plasticizer to form pores; and stretching and heat-setting the mixture in which the pores are formed to manufacture a porous polymer substrate.

[0119] The method for manufacturing an electrochemical device according to one embodiment of the present invention can easily prevent an increase in the resistance of a separator and improve the energy density of a battery by manufacturing the separator as a thin film. In the method for manufacturing a separator for an electrochemical device according to one embodiment of the present invention, any description overlapping with the description of the separator for an electrochemical device will be omitted.

[0120] According to one embodiment of the present invention, a method for manufacturing a separator for an electrochemical device is provided, comprising the steps of: applying a slurry for a coating layer including a first polymer binder (131) and inorganic particles (133) on at least one surface of the porous polymer substrate (110); and applying a slurry for an adhesive layer including a second polymer binder (151).

[0121] According to one embodiment of the present invention, the method for manufacturing the electrochemical device includes a step of applying a slurry for a coating layer including a first polymer binder (131) and inorganic particles (133) onto at least one surface of a porous polymer substrate (110). By including the step of applying the slurry for a coating layer onto at least one surface of the porous polymer substrate as described above, a coating layer can be formed with a single application, and the content of inorganic particles in the slurry for a coating layer is excessive, thereby improving the heat resistance of the separator and facilitating evaporation of a solvent.

[0122] According to one embodiment of the present invention, prior to the step of applying the slurry for the coating layer, a polymer solution may be prepared by dissolving the first polymer binder in an appropriate solvent to prepare a slurry. The solvent is preferably one having a solubility index similar to that of the binder polymer to be used and a low boiling point. This is to facilitate uniform mixing and subsequent solvent removal. Non-limiting examples of usable solvents include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or mixtures thereof.

[0123] According to one embodiment of the present invention, prior to the step of applying the slurry for the coating layer, a polymer emulsion may be prepared by dispersing a first polymer binder in an appropriate dispersion medium to prepare a slurry. The dispersion medium preferably has a low boiling point. This is to facilitate uniform mixing and subsequent removal of the dispersion medium. Non-limiting examples of usable dispersion mediums include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or mixtures thereof.

[0124] According to one embodiment of the present invention, inorganic particles may be added and dispersed in the polymer emulsion or polymer solution. The content ratio of the inorganic particles and the polymer binder particles is as described above, and may be appropriately adjusted in consideration of the thickness, pore size, and porosity of the coating layer to be finally manufactured according to one embodiment of the present invention.

[0125] 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 30 wt% or less. Specifically, the solid content of the slurry for the coating layer may be 11 wt% or more and 29 wt% or less, 12 wt% or more and 28 wt% or less, 13 wt% or more and 27 wt% or less, 14 wt% or more and 26 wt% or less, 15 wt% or more and 25 wt% or less, 16 wt% or more and 24 wt% or less, 17 wt% or more and 23 wt% or less, 18 wt% or more and 22 wt% or less, or 19 wt% or more and 21 wt% or less. By controlling the solid content of the slurry for the coating layer within the above-described range, an increase in the resistance of the separator can be prevented, and the separator can be manufactured into a thin film to improve the energy density of the battery.

[0126] According to one embodiment of the present invention, the method of applying the slurry for the coating layer to the surface of the porous polymer substrate (110) is not particularly limited to any one method, and a conventional method known in the art may be used. For example, various methods such as dip coating, die coating, roll coating, comma coating, or a mixture thereof may be used.

[0127] According to one embodiment of the present invention, the method for manufacturing the electrochemical device includes a step of applying a slurry for an adhesive layer including a second polymer binder (151). By including the step of applying a slurry for an adhesive layer including a second polymer binder (151) as described above, the adhesive layer can be easily formed.

[0128] According to one embodiment of the present invention, the method for applying the slurry for the adhesive layer to the surface of the porous polymer substrate (110) is not particularly limited to any one method, and a conventional method known in the art may be used. For example, various methods such as dip coating, die coating, roll coating, comma coating, or a mixture thereof may be used.

[0129] According to one embodiment of the present invention, the slurry for the adhesive layer may further include a dispersion medium, and the dispersion medium may be water. As described above, by the slurry for the adhesive layer further including a dispersion medium, the second polymer binder can be uniformly dispersed.

[0130] According to one embodiment of the present invention, the method for manufacturing the electrochemical device may include a step of drying the slurry for the coating layer to form a coating layer. By including the step of drying the slurry for the coating layer to form a coating layer as described above, damage to the coating layer can be minimized, and the solvent or dispersion medium included in the slurry can be easily removed.

[0131] According to one embodiment of the present invention, the method for manufacturing the electrochemical device may include a step of drying the slurry for the adhesive layer to form an adhesive layer. By including the step of drying the slurry for the adhesive layer to form an adhesive layer as described above, damage to the adhesive layer can be minimized, and the dispersion medium included in the slurry can be easily removed.

[0132] According to one embodiment of the present invention, the method for manufacturing the electrochemical device may include a step of applying a slurry for a coating layer, drying the slurry for an adhesive layer, and then drying the slurry for an adhesive layer to form a coating layer and an adhesive layer, respectively. As described above, by including a step of applying a slurry for a coating layer, drying the slurry for an adhesive layer, and then drying the slurry for an adhesive layer to form a coating layer and an adhesive layer, respectively, the coating layer and the adhesive layer can be easily formed.

[0133] According to one embodiment of the present invention, the drying process appropriately sets time conditions to minimize the occurrence of surface defects in the coating layer. The drying may be performed using a drying assist device, such as a drying oven or hot air, within an appropriate range.

[0134] According to one embodiment of the present invention, the separator is interposed between the negative electrode and the positive electrode and is manufactured into an electrode assembly through a lamination process that applies heat and / or pressure to bond them. In one embodiment of the present invention, the lamination process can be performed by a roll press device including a pair of pressure rollers. That is, the negative electrode, the separator, and the positive electrode can be sequentially laminated and placed between the pressure rollers to achieve interlayer bonding. At this time, the lamination process can be performed by a hot press method.

[0135] One embodiment of the present invention provides an electrochemical device comprising a positive electrode (300); a negative electrode (500); and a separator (100), wherein the separator (100) is interposed between the positive electrode (300) and the negative electrode (500), and is a separator for an electrochemical device.

[0136] An electrochemical device according to one embodiment of the present invention can improve the performance of a battery and extend the life of the battery.

[0137] Figure 3 is a schematic diagram of an electrochemical device according to one embodiment of the present invention. Referring to Figure 3, the electrochemical device according to one embodiment of the present invention will be described in detail.

[0138] In this specification, the electrochemical device is a device that converts chemical energy into electrical energy through an electrochemical reaction, and is a concept encompassing primary batteries and secondary batteries. In this specification, the secondary battery is capable of charging and discharging, and refers to a lithium secondary battery, a nickel-cadmium battery, a nickel-hydrogen battery, etc. The lithium secondary battery uses lithium ions as an ion conductor, and examples thereof include, but are not limited to, a non-aqueous electrolyte secondary battery including a liquid electrolyte, an all-solid-state battery including a solid electrolyte, a lithium polymer battery including a gel polymer electrolyte, and a lithium metal battery using lithium metal as an anode.

[0139] According to one embodiment of the present invention, the positive electrode has a positive electrode current collector and a positive electrode active material layer including a positive electrode active material, a conductive material, and a binder resin on at least one surface of the positive electrode current collector. The positive electrode active material is a layered compound such as lithium manganese oxide (LiMn2O4, LiMnO2, etc.), lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; chemical formula Li 1+x Mn 2-x Lithium manganese oxides such as O4 (where x is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, Cu2V2O7; chemical formula LiNi 1-x M xNi-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.

[0140] According to one embodiment of the present invention, the negative electrode has a negative electrode current collector and a negative electrode active material layer including a negative electrode active material, a conductive material, and a binder resin on at least one surface of the current collector. The negative electrode includes carbon such as lithium metal oxide, non-graphitizable carbon, and graphite carbon as the negative electrode active material; LixFe2O3(0≤x≤1), Li x WO2(0≤x≤1), Sn x Me 1-x Me' y O z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, elements of group 1, 2, and 3 of the periodic table, halogens; 0 <x≤1; 1≤y≤3; 1≤z≤8) 등의 금속 복합 산화물; 리튬 금속; 리튬 합금; 규소계 합금; 주석계 합금; SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, 및 Bi2O5등의 금속 산화물; 폴리아세틸렌 등의 도전성 고분자; Li-Co-Ni 계 재료; 티타늄 산화물 중 선택된 1종 또는 2종 이상의 혼합물을 포함할 수 있다.

[0141] 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.

[0142] 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.

[0143] 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.

[0144] In the present invention, the positive electrode slurry for manufacturing the positive electrode active material layer may include a dispersant, and the dispersant may be a pyrrolidone-based compound. 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 ions composed of alkali metal cations or combinations 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] According to one embodiment of the present invention, the first part of the separator may be arranged to face the anode, and the second part of the separator may be arranged to face the cathode. Specifically, the first part of the separator may be formed to contact the anode, and the second part of the separator may be formed to contact the cathode. As described above, by implementing that the first part of the separator is arranged to face the anode, and the second part of the separator is arranged to face the cathode, the capture efficiency of transition metal ions generated at the anode can be improved, and pore blockage can be prevented.

[0152] 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.

[0153] <Example 1>

[0154] (1) Membrane manufacturing

[0155] A first mixture comprising polyethylene (weight average molecular weight of 900,000) and Al2O3 powder having a D50 particle size of 600 nm as an inorganic particle was mixed in a weight ratio of 80:20 as a first part, and a second mixture comprising polyethylene (weight average molecular weight of 900,000) and Al2O3 powder having a D50 particle size of 600 nm as an inorganic particle was co-extruded in a weight ratio of 95:5 as a second part, and the stretching temperature was adjusted to 105°C and the heat setting temperature to 130°C, thereby manufacturing a porous polymer substrate (total thickness: 8 μm, thickness of the first part: 4 μm, thickness of the second part: 4 μm, porosity of the first part: 60 vol%, porosity of the second part: 45 vol%) made of a polyolefin resin material by a wet method.

[0156] (2) Manufacturing of the anode

[0157] A slurry for a cathode active material layer was prepared by mixing a cathode active material (LiNi0.8Mn0.1Co0.1O2), a conductive agent (carbon black), a dispersant (N-methylpyrrolidone, ADC-01, LG Chemical), and a binder resin (a mixture of PVDF-HFP and PVDF) with water in a weight ratio of 97.5:0.7:0.14:1.66, with the remaining components excluding water at a concentration of 50 wt%. Next, the slurry was applied to the surface of an aluminum thin film (thickness 10 μm) and dried to manufacture a cathode having a cathode active material layer (thickness 120 μm).

[0158] (3) Manufacturing of cathode

[0159] 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).

[0160] (4) Lamination process

[0161] An electrochemical device was obtained by interposing a separator of the embodiment between the cathode and anode manufactured above, stacking them, and performing a lamination process. The first portion of the separator was interposed so as to be in contact with the anode. The lamination process was performed using a hot press at 70°C and 5.2 MPa for 10 seconds.

[0162] <Example 2>

[0163] An electrochemical device was manufactured in the same manner as in Example 1, except that the porosity of the first part was 45% by volume and the porosity of the second part was 60% by volume.

[0164] <Example 3>

[0165] An electrochemical device was manufactured in the same manner as in Example 1, except that the porosity of the first part was 50% by volume and the porosity of the second part was 50% by volume.

[0166]

[0167] <Comparative Example 1>

[0168] An electrochemical device was manufactured in the same manner as in Example 1, except that a separator was manufactured as described below in Example 1 and the separator of Comparative Example 1 was interposed between the manufactured cathode and anode.

[0169] (1) Manufacturing of membrane

[0170] A mixture of polyethylene (weight average molecular weight: 900,000) and Al2O3 powder having a D50 particle size of 600 nm as inorganic particles was mixed in a weight ratio of 80:20, and the mixture was extruded, and the stretching temperature was adjusted to 105°C and the heat setting temperature to 130°C, thereby manufacturing a porous polymer substrate (total thickness: 8 μm) made of polyolefin resin material using a wet method.

[0171] <Comparative Example 2>

[0172] An electrochemical device was manufactured in the same manner as in Example 1, except that a separator was manufactured as in Example 1 and the positive electrode and the second part of the separator were interposed so as to be in contact with the positive electrode.

[0173]

[0174] <Experimental Example 1: Membrane Permeability Measurement>

[0175] The air permeability (air permeability time, Gurley) of the membranes manufactured in the manufacturing processes of Example 1 and Comparative Examples 1 and 2 was measured by the ASTM D-2873 method. The Gurley value was measured using a Gurley type Densometer (No. 158) from Toyoseiki according to the Gurley (JIS) measurement method of the Japanese Industrial Standard. The air permeability value was measured when 100 ml of air was applied to 1 in of the membrane under a pressure of 12.2 in H2O. 2 The time (in seconds) it takes to pass through the cross section is expressed as the ventilation time.

[0176]

[0177] <Experimental Example 2: Measurement of Insulation Breakdown Voltage>

[0178] The breakdown voltage was measured using an AC / DC / IR Hi-Pot tester.

[0179] A membrane sample cut into 5 x 5 cm was placed between aluminum jigs (upper jig diameter 30 mm, lower jig 50 x 100 mm), and the voltage at which a fail condition (> 0.5 mA, 3 sec) occurred was measured using a Hi-pot tester. The measurement conditions were set to DC, current 0.5 mA, and voltage step-up 100 V / s (up to 3 kV). The measured value was expressed as the average value of 30 samples.

[0180]

[0181] <Experimental Example 3: Short circuit defect during assembly>

[0182] When a voltage of 50 V was applied for 0.1 second to the electrochemical devices of Example 1 and Comparative Examples 1 and 2, if the flowing current was 0.5 mA or more, it was judged to be a short-circuit defect. Ten electrochemical devices each of Example 1 and Comparative Examples 1 and 2 were manufactured to determine whether a short-circuit defect occurred.

[0183]

[0184] <Experimental Example 4: Measurement of Cycle Capacity Maintenance Rate>

[0185] The electrochemical devices of Example 1 and Comparative Examples 1 and 2 were charged and discharged once at 0.1 C in the voltage range from 3.0 V to 4.4 V in a 25°C chamber, and then the life characteristics were measured for 300 cycles while charging at 1.0 C and discharging at 1.0 C. At this time, the life characteristics were expressed as a capacity retention rate calculated by the ratio of the discharge capacity after 300 cycles to the discharge capacity at the first cycle.

[0186]

[0187] <Experimental Example 5: Resistance Increase Rate>

[0188] The increase rate of DCIR resistance was measured before and after 300 cycles for the electrochemical devices of Example 1 and Comparative Examples 1 and 2 above. At this time, the DCIR resistance is the value obtained by measuring the resistance when discharging for 10 seconds at 2.5 C at 50% SOC (State of Charge).

[0189]

[0190] Membrane permeability (sec / 100cc) Insulation breakdown voltage (V) Short circuit failure cycle capacity retention rate @ 300 cycles (%) Resistance increase rate (before and after cycles) (%) Example 1654, 5210 / 10933.4 Example 2654, 5180 / 10858.1 Example 3684, 5730 / 10906.1 Comparative example 1472, 2633 / 10875.2 Comparative example 2654, 5210 / 10858.2

[0191]

[0192] Referring to Table 1 above, it was confirmed that Comparative Example 1 was not suitable for use as a separator because the porosity of the separator was excessively high, resulting in problems with insulation. Furthermore, it was confirmed that Comparative Example 2 caused metal ions generated at the anode surface to accumulate in the porous polymer substrate with low porosity, thereby degrading the performance of the electrochemical device.

[0193] In this regard, Examples 1 to 3 used a separator including a first part and a second part in which pores of appropriate sizes were formed, thereby realizing appropriate ventilation and confirming that the electrochemical device performance was not deteriorated compared to the comparative example.

[0194]

[0195] Ultimately, the separator for an electrochemical device according to one embodiment of the present invention can prevent pore blockage by controlling the pore size, porosity, and content of inorganic particles in the portion adjacent to and spaced from the anode, and improve the capture efficiency of transition metal ions generated from the anode, thereby preventing battery degradation and improving the lifespan of the battery.

[0196] [Explanation of symbols]

[0197] 100: Separator for electrochemical devices

[0198] 110: Porous polymer substrate

[0199] 111: Part 1

[0200] 113: Part 2

[0201] 130: Coating layer

[0202] 131: First polymer binder

[0203] 133: Inorganic particles

[0204] 150: Adhesive layer

[0205] 151: Second polymer binder

[0206] 300: Bipolar

[0207] 500: negative

Claims

1. Includes a porous polymer substrate containing inorganic particles, It comprises a first part adjacent to one side of the porous polymer substrate and a second part facing the first part, The weight of the inorganic particles included in the first part is greater than the weight of the inorganic particles included in the second part, A separator for an electrochemical device, wherein the above inorganic particles are capable of adsorbing transition metal ions.

2. In claim 1, A separator for an electrochemical device, wherein the inorganic particles are one selected from the group consisting of zeolite, silica gel, carbon fiber, porous carbon, porous metal oxide, metal-organic framework (MOF), and combinations thereof.

3. In claim 1, A separator for an electrochemical device, wherein the inorganic particles included in the first part and the inorganic particles included in the second part are the same or different.

4. In claim 1, A separator for an electrochemical device, wherein the above porous polymer substrate is a polyolefin-based resin.

5. In claim 1, A separator for an electrochemical device, wherein the size of the pores included in the first part is larger than the size of the pores included in the second part.

6. In claim 1, The size of the pores included in the first part is 20 ㎛ or more and 100 ㎛ or less, A separator for an electrochemical device, wherein the size of the pores included in the second part is 20 ㎛ or more and 100 ㎛ or less.

7. In claim 1, A separator for an electrochemical device, wherein the porosity of the first portion is greater than the porosity contained in the second portion.

8. In claim 1, The porosity of the first part is 50% by volume or more and 70% by volume or less, A separator for an electrochemical device, wherein the porosity of the second portion is 40% by volume or more and 50% by volume or less.

9. In claim 1, A separator for a battery chemical device, wherein the thickness of the first portion is equal to or smaller than the thickness of the second portion.

10. In claim 1, A separator for a battery chemical device, wherein the first part is provided to be adjacent to the positive electrode.

11. In claim 1, A separator for a battery chemical device, wherein a portion of the surface of the above-mentioned inorganic particles is included to protrude outward from the above-mentioned porous polymer substrate.

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

13. Containing an anode; a cathode; and a separator, An electrochemical device, wherein the separator is interposed between the anode and the cathode, and is a separator for an electrochemical device according to any one of claims 1 to 12.

14. In claim 13, The first part of the above separator is arranged to face the anode, An electrochemical device wherein the second part of the separator is positioned to face the cathode.

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