KR20220021857A - Separator for Electrochemical Device - Google Patents

Abstract

The present invention relates to a composite separator for an electrochemical device. The composite separator according to the present invention includes a porous substrate and crystalline metal salt. The composite separator can act as a salt source for a liquid electrolyte of an electrochemical device, and can show flame retardancy by metal salt together with or independently of the liquid electrolyte.

Description

Separator for Electrochemical Device

The present invention relates to a separator for an electrochemical device, and specifically, an electrochemical device capable of exhibiting improved flame retardancy and/or improved ionic conductivity, and an electrochemical device having a high concentration electrolyte together with or independently thereof It relates to a separator for a device.

In accordance with the trend toward higher performance, lighter weight, and larger sizes of electrochemical devices, such as for automotive power, research on high energy density and large capacity is being actively conducted. Research is being carried out for high-capacity and high-output for each element constituting an electrochemical device, such as electrode materials that can realize higher energy density, thinner and improved wettability separators, and electrolytes with improved conductivity. For the commercialization of medium-to-large electrochemical devices for this purpose, safety (removal of the risk of explosion) must be secured first.

The separator prevents a short circuit by preventing physical contact between the two electrodes in the electrochemical device and at the same time provides a path for ions to pass through. It provides a closure function to block the stoma.

For high-capacity and high-output electrochemical devices, a separator with low closing temperature and higher short-circuit temperature, low thermal contraction rate, excellent cycle performance due to high ionic conductivity, excellent electrolyte wettability, is required, and safety of electrochemical devices In order to secure, the development of a separator having excellent flame retardancy is required.

Republic of Korea Patent Publication No. 2016-0025079

An object of the present invention is to provide a separator having excellent flame retardancy.

Another object of the present invention is to provide a separator having improved thermal stability.

Another object of the present invention is to provide a separation membrane having improved ionic conductivity.

Another object of the present invention is to provide a separator having excellent liquid electrolyte wettability.

Another object of the present invention is to provide a separator capable of implementing an electrochemical cell provided with a high-concentration liquid electrolyte.

Another object of the present invention is to provide an electrochemical cell having improved at least one property of flame retardancy, thermal stability, ionic conductivity, electrolyte wettability, and productivity, and a method for manufacturing the same.

Another object of the present invention is to provide a coating solution for use in the manufacture of an electrochemical cell having improved one or more properties of flame retardancy, thermal stability, ionic conductivity, electrolyte wettability, and productivity.

The composite separator according to the present invention is for an electrochemical device, and includes a porous substrate; and crystalline metal salts.

In the composite separator according to an embodiment, the metal salt may include a metal salt containing a sulfonyl group.

In the composite separator according to an embodiment, the porous substrate may include a porous film, and the metal salt may be located on the surface of the porous film.

In the composite separator according to an embodiment, the porous substrate includes: a porous film; and a porous coating layer positioned on at least one surface of the porous film, and the metal salt may be positioned in one or more regions of the interface between the porous film and the porous coating layer, the inside of the porous coating layer, and the surface of the porous coating layer.

In the composite separator according to an embodiment, the porous coating layer may include inorganic particles, organic particles, organic-inorganic composite particles, or mixed particles thereof.

In the composite separator according to an embodiment, the metal salt containing a sulfonyl group may be any one or more selected from compounds satisfying the following Chemical Formulas 1 to 4.

(Formula 1)

In Formula 1, A ⁺ is a monovalent cation, and R ₁ is F, CFH ₂ , CF ₂ H, or C _n F _2n+1 (n is a natural number greater than or equal to 1).

(Formula 2)

In Formula 2, A ²⁺ is a divalent cation, and R ₁ is F, CFH ₂ , CF ₂ H, or C _n F _2n+1 (n is a natural number greater than or equal to 1).

(Formula 3)

In Formula 3, A ⁺ is a monovalent cation, and R ₁ and R ₂ are each independently F, CFH ₂ , CF ₂ H, or C _n F _2n+1 (n is a natural number greater than or equal to 1).

(Formula 4)

In Formula 4, A ²⁺ is a divalent cation, and R ₁ and R ₂ are each independently F, CFH ₂ , CF ₂ H, or C _n F _2n+1 (n is a natural number greater than or equal to 1).

In the composite separator according to an embodiment, the composite separator may be a salt source for supplying a metal salt to an electrolyte provided in an electrochemical device.

In the composite separator according to an embodiment, the metal salt may be fixed by any one or more binding components selected from linear polymers and crosslinked polymers.

In the composite separator according to an embodiment, the fixing may be accomplished by curing a curing component having hardenability, which is converted into a binding component by curing, in a mixed state with a metal salt.

In the composite separator according to an embodiment, the composite separator is located on one side of the porous substrate and may include a coating layer containing a metal salt.

In the composite separator according to an embodiment, the porous substrate includes: a porous film; and a porous coating layer positioned on at least one surface of the porous film, wherein the composite separator is between the porous film and the porous coating layer, the surface region of the porous coating layer, or between the porous film and the porous coating layer and the surface region of the porous coating layer, respectively. and may include a coating layer containing a metal salt.

In the composite separator according to an embodiment, the coating layer containing the metal salt may further contain one or more polymers selected from linear polymers and crosslinked polymers.

In the composite separator according to an embodiment, the metal salt content, which is the mass of the metal salt per unit area of the porous substrate, may be 0.1 to 5.0 mg/cm ² .

In the composite separator according to an embodiment, the metal ion participating in the electrochemical reaction of the electrochemical device provided with the composite separator is the active ion, and the metal ion of the metal salt may include the active ion.

The composite separator according to an embodiment may satisfy Equation 1 below.

(Equation 1)

5(%) ≤ (Wdry-Wwet)/Wm x 100(%)

In Equation 1, Wdry is the mass of the composite separator before contact with the electrolyte, and Wwet is a mixed solvent in which ethylene carbonate and dimethyl carbonate are mixed in a volume ratio of 1:1 with LiPF ₆ dissolved at a concentration of 1M. It is the mass of the composite separator recovered and dried after immersion at 25° C. for 1 hour, and Wm is the mass of the metal salt contained in the composite separator before contact with the electrolyte.

The present invention includes a flame retardant separator.

The flame-retardant separator according to the present invention is recovered after being impregnated with the following reference electrolyte for 1 minute, and immediately after recovery, when the direction of gravity and the in-plane direction of the separator are positioned parallel to each other, droplets fall from the separator to the floor for 1 minute In the following flame-retardant test performed at a time when not in use, no flame is generated from the separator.

Reference electrolyte: mixed solvent of ethylene carbonate and dimethyl carbonate in a volume ratio of 1:1, lithium salt of LiPF ₆ , LiPF ₆ concentration of 1M, temperature of 25℃ ± 5℃

Flame-retardant test: the length of the flame in the air = 5 to 10 cm, the flame tip temperature = 1000 to 1500 ° C, the length of the flame region that is not in contact with the separator when the flame is applied to the separator = 50 to 80% of the length of the flame in the air, the flame moving speed in contact with the separator = 1 to 5 cm/sec

The present invention includes an electrochemical device including the above-described composite separator for an electrochemical device.

The present invention includes an electrochemical device including the above-described flame-retardant separator.

In the electrochemical device according to an embodiment, a metal ion participating in the electrochemical reaction of the electrochemical device as an active ion, the molar concentration of the salt of the active ion contained in the electrolyte may be 0.5 to 6.0M.

An electrochemical device according to the present invention includes an anode; cathode; a separator interposed between the anode and the cathode; and an electrolyte; with metal ions participating in the electrochemical reaction as active ions, the electrolyte is a high-concentration electrolyte containing 1M or more salts of active ions, and in a state wetted to the electrolyte, the ionic conductivity of the separator is 0.3 mS/cm or more, and the ion mobility coefficient of the active ions of the separation membrane is 0.3 or more.

The present invention includes an electrochemical module (secondary battery module) in which two or more of the above-described electrochemical devices are electrically connected.

The present invention includes a device powered by an energy storage device including the electrochemical device described above.

The composite separator according to an embodiment of the present invention contains a crystalline metal salt, and has the advantage of being able to convert a low-concentration electrolyte into a high-concentration electrolyte within the electrochemical device.

The composite separator according to an embodiment of the present invention has crystallinity and contains a metal salt containing a sulfonyl group, and thus has the advantage of exhibiting flame retardancy and, furthermore, remarkably improved ionic conductivity.

The composite separator according to the present invention does not substantially change the established components and manufacturing process in an electrolyte-based electrochemical device, and can adopt conventionally established processes and materials substantially as it is, and has wettability There is an advantage in that it is possible to implement an electrochemical device having a high concentration liquid electrolyte without causing deterioration or a decrease in productivity, an electrochemical device having improved safety due to flame retardancy, and/or an electrochemical device having excellent electrochemical properties by improved ionic conductivity. .

1 is a photograph evaluating the flame retardancy of Example 3.
2 is a photograph evaluating the flame retardancy of Example 4.
3 is a photograph evaluating the flame retardancy of Example 5.
4 is a photograph evaluating the flame retardancy of Example 6.
5 is a photograph evaluating the flame retardancy of Example 7.
6 is a photograph evaluating the flame retardancy of Example 8.
7 is a photograph evaluating the flame retardancy of Example 9.
8 is a photograph evaluating the flame retardancy of Comparative Example 1.
9 is an evaluation result of X-ray diffraction analysis of Comparative Example 1, Comparative Example 3 and Example 7.
10 is a result of evaluating the adhesive strength characteristics of Comparative Examples 3 and 7.
11 is a result of evaluating the volatilization characteristics of Comparative Examples 3 and 7.

Hereinafter, a separator, an electrochemical device, and a manufacturing method thereof according to the present invention will be described in detail with reference to the accompanying drawings. The drawings introduced below are provided as examples so that the spirit of the present invention can be sufficiently conveyed to those skilled in the art. Accordingly, the present invention is not limited to the drawings presented below and may be embodied in other forms, and the drawings presented below may be exaggerated to clarify the spirit of the present invention. At this time, if there is no other definition in the technical terms and scientific terms used, it has the meaning commonly understood by those of ordinary skill in the art to which this invention belongs, and the gist of the present invention in the following description and accompanying drawings Descriptions of known functions and configurations that may be unnecessarily obscure will be omitted.

Further, the singular forms used in the specification and appended claims may also be intended to include the plural forms unless the context specifically dictates otherwise.

In this specification and the appended claims, terms such as first, second, etc. are used for the purpose of distinguishing one element from another, not in a limiting sense.

In this specification and the appended claims, the terms include or have means that a feature or element described in the specification is present, and unless specifically limited, one or more other features or elements may be added. This is not to rule out the possibility in advance.

In this specification and the appended claims, when a part of a film (layer), region, component, etc. is said to be on or on another part, not only when it is directly on the other part in contact with it, but also another film (layer) in the middle. ), other areas, and other components are also included.

The electrode assembly of the anode/separator/cathode structure constituting the electrochemical device is usually surrounded by a separation film on the outside, and the separation film is present in multiple layers on the side of some full cells or bi-cells, resulting in poor wettability when impregnated with electrolyte and the device There is a problem that it takes a long time in the manufacturing process.

A high concentration of electrolyte is required in a medium-to-large electrochemical device that requires safety, output/energy density, and long-life characteristics, and the high-concentration electrolyte has the following advantages. (1) Safety improvement: When the electrolyte salt is highly concentrated, the number of free solvent molecules that do not participate in solvation is extremely reduced, and thus volatility is suppressed to have flame retardant properties, and charging and discharging processes It has the effect of suppressing the side reaction of solvent molecules involved in ; (2) Improvement of electrochemical properties: In a high-concentration electrolyte in which almost no free solvent molecules exist, the movement mechanism of active ions moves through hopping between the metal salt-solvent complex in the existing Vehicle-Type, and accordingly, the ionic conductivity of the active metal salt will increase In addition, in the case of a low-concentration electrolyte containing a large number of free solvent molecules, compared to the SEI component in which the reduction reaction of the solvent is dominant, the SEI component of the high-concentration electrolyte has a prominent anion-derived component, and the anion-derived SEI is the active metal salt at the electrode/electrolyte interface. It is known to improve the output characteristics by lowering the resistance of the Electron Transfer Reaction; (3) Improvement of lifespan characteristics: In addition to the aforementioned improvement in power density, the high-concentration electrolyte with almost no free solvent molecules suppresses the elution problem of transition metal ions, which causes issues of battery life and safety, so that the lifespan characteristics of the battery are improved. will be improved

However, the higher the concentration of the electrolyte, the stronger the ionic strength, so the high-concentration electrolyte has a high viscosity. The viscosity of the commonly used low-concentration electrolyte is about 3 mPa, but the viscosity of 5.5M LiFSI/DMC (Lithium bis(fluorosulfonyl)imid/dimethyl carbonate), which is known as a representative high-concentration electrolyte, is about 240 mPa, showing a very high viscosity. The above-mentioned problems related to the wettability are aggravated, deteriorating the uniformity of battery quality and productivity.

As a result of continuing research on an electrochemical device having a high-concentration liquid electrolyte, the present applicant has substantially advanced the established components and manufacturing process in a small electrochemical device, that is, a low-concentration electrolyte-based electrochemical device. A technology capable of realizing an electrochemical device equipped with a high-concentration liquid electrolyte has been developed, which can be adopted substantially as it is without changing the previously established processes and materials, and does not cause deterioration of wettability or reduced productivity.

In addition, in the course of further in-depth research on these technologies, it was confirmed that certain materials impart a high degree of flame retardancy to the electrochemical device. reached

A composite separator according to the present invention is a composite separator for an electrochemical device, comprising: a porous substrate; and crystalline metal salts.

In the present invention, when the composite separator contains a crystalline metal salt, it may mean that at least one diffraction peak of the metal salt exists in the X-ray diffraction pattern of the composite separator, and diffraction of the crystal plane in the known crystal structure of the metal salt It may mean that a peak exists. The X-ray diffraction pattern of the composite separator may be one using Cu Kα rays. In this case, the X-ray diffraction pattern of the metal salt, which is a criterion for the presence of the crystalline metal salt, may be based on a previously established library (JCPDS, ICSD, CSD), and the X-ray on the crystalline metal salt powder in the established library It may be based on a diffraction pattern.

The composite separator according to an embodiment of the present invention includes a metal salt together with the porous substrate, so that the metal salt can be supplied to the liquid electrolyte upon contact with the liquid electrolyte, and the concentration of the salt in the liquid electrolyte in contact with the composite separator can be increased. .

As described above, when the composite separator according to an embodiment is provided in a liquid electrolyte-based electrochemical cell, a metal salt may be supplied to the liquid electrolyte. Accordingly, the liquid electrolyte can be converted into a high-concentration electrolyte in the electrochemical cell by the composite separator.

In this aspect, the composite separator according to an embodiment of the present invention includes a porous substrate; and a crystalline metal salt that can be dissolved (in a soluble form) in the liquid medium upon contact with the liquid medium containing the solvent of the metal salt. At this time, the solvent of the metal salt, at room temperature (10 to 30° C.) and atmospheric pressure, has a solubility for the metal salt of 0.1 g/liquid material 100 g or more, specifically 0.5 g/ liquid material 100 g or more, more specifically 1.0 g/ Liquid substance It can be interpreted as a liquid substance with more than 100g.

In addition, experimentally, when the metal salt is dissolved in the liquid medium upon contact with the liquid medium or the metal salt contained in the composite separator is in a soluble form, it means that the composite separator satisfies Equation 1 below.

(Equation 1)

5(%) ≤ (Wdry-Wwet)/Wm x 100(%)

In Equation 1, Wdry is the mass of the composite separator before contact with the electrolyte, and Wwet is a mixed solvent in which ethylene carbonate and dimethyl carbonate are mixed in a volume ratio of 1:1 with LiPF ₆ dissolved at a concentration of 1M. It is the mass of the composite separator recovered and dried after immersion at 25° C. for 1 hour, and Wm is the mass of the metal salt contained in the composite separator before contact with the electrolyte. At this time, the recovered composite separator may be dried under conditions in which all of the solvent of the reference electrolyte solution is removed by volatilization. However, the present invention is not limited thereto. In addition, the volume of the reference electrolyte in which the composite separator is completely submerged is ok as long as the mass of the composite separator is not affected by the volume of the reference electrolyte after contact with the electrolyte. For example, the volume of the reference electrolyte is based on the apparent volume of the composite separator It may be 50 to 1000 times the level, but is not necessarily limited thereto.

Equation 1 means the dissolution rate (%) in which the metal salt contained in the composite separator is dissolved when the composite separator is immersed in the standard electrolyte for 1 hour. The composite separator according to an embodiment has a dissolution rate defined by (Wdry-Wwet)/Wm x 100 (%) of Equation 2 of 5% or more, 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 45% or more, 50% or more, 55% or more, 60% or more, 65% or more, 70% or more, 75% or more, 80% or more, 85% or more, 90% or more, 95% or greater, or substantially up to 100%. A dissolution rate of 100% means that all metal salts contained in the composite separator are dissolved in the standard electrolyte before contact with the electrolyte.

As the composite separator contains the metal salt in a crystalline form, it may have a dissolution rate of the degree specified in Equation 1 regardless of the presence or absence of a binder (binding component) to be described later. However, when the crystalline metal salt is bound (including adsorption) to the porous substrate alone without a binder (binding component), 30% or more, 40% or more, 50% or more, 60% or more, 70% or more , can have a high dissolution rate that can reach 80% or more, 90% or more or substantially 100%. The composite separator having such a high dissolution rate is obtained by injecting an electrode assembly including an anode, a separator, and a cathode into the case of an electrochemical device and injecting a liquid electrolyte (a liquid electrolyte having a lower concentration than the desired salt concentration, which is easy to inject). With only a well-established and well-known process, an electrochemical device having a high concentration electrolyte can be manufactured without causing problems occurring in the conventional high concentration electrolyte.

The composite separator, which serves as a salt source for converting a low-concentration electrolyte into a high-concentration electrolyte inside the electrochemical device by injecting a low-concentration electrolyte, is a crystalline metal salt and preferably contains a metal salt of an active ion. That is, it is preferable that the metal ion participating in the electrochemical reaction of the electrochemical device provided with the composite separator as the active ion, the metal ion of the crystalline metal salt contains the active ion, and substantially, the crystalline metal salt is the active ion of the active ion. Preferably it is a crystalline salt. In this case, the solute (electrolyte salt) contained in the low-concentration electrolyte and the crystalline metal salt contained in the composite separator may be the same or different materials.

Even after the composite separator provides the metal salt as a solute (electrolyte salt) by contacting the liquid medium containing the liquid electrolyte or solvent injected in the electrochemical device manufacturing process, the concentration of the metal salt in the porous substrate (including the meaning of adjacent) is It can be maintained for a long time in a relatively high state compared to the anode and the cathode. According to the concentration gradient formed by the metal salt derived from the separator (composite separator), the electrolyte components in the separator, the anode, and the cathode have different surface tensions, and there is no external force such as a separate convection force. The concentration of the metal salt derived from the separator in the inside can be maintained for a long time in a relatively high state compared to the positive electrode and the negative electrode. By this concentration gradient, thermal stability or flame retardancy of the separation membrane and/or ionic conductivity of active metal ions may be improved.

That is, in an electrochemical device manufactured by charging an electrode assembly including a positive electrode, a composite separator, and a negative electrode in a case and injecting and sealing a liquid electrolyte, even if the dissolution rate of the charged composite separator reaches 100%, the composite separator The concentration of the solute (electrolyte salt) in the electrolyte region in contact with the side and the electrolyte region in contact with the electrode may be different, and the concentration (CH) of the electrolyte region in contact with the composite separator in the entire electrolyte region is relatively high, and the electrolyte in contact with the electrode The concentration CL of the region may be relatively low. That is, CH and CL may satisfy the relationship of CH>CL, substantially CH>1.5CL. A liquid electrolyte having a non-uniform concentration may have a concentration gradient in a direction in which the concentration of a solute (electrolyte salt) decreases in the electrode direction in the composite separator. In this case, the concentration gradient may decrease substantially continuously in the direction of the electrode in the composite separator.

In the composite separator according to an embodiment, in consideration of a commercial composite separator manufacturing process, and in consideration of smooth contact and/or a large contact area between the liquid electrolyte and the metal salt contained in the composite separator, in the composite separator, the crystalline metal salt is It may be located in the surface region of the porous substrate.

The crystalline metal salt positioned on the surface region of the porous substrate may include a metal salt in an adsorbed and/or immobilized state. In this case, the adsorption may include physical adsorption and/or chemisorption. In addition, the fixing may include fixing of the metal salt itself by bonding to the porous substrate and/or fixing by a material different from the metal salt, that is, fixing by an external factor including a different material. In this case, the heterogeneous material fixing the metal salt may be deformed (eg, swollen) or dissolved by the liquid medium or solvent, and the metal salt may be changed into a form soluble in the liquid medium or solvent.

The surface area of the porous substrate may mean a region from one surface to 0.05 to 0.3 t _pm in the thickness direction of the porous substrate from one surface, with the total thickness of the porous substrate (the shortest distance between the two widest surfaces facing each other) as t _pm . However, it is not necessarily limited thereto. The surface area of the porous substrate may be more substantially defined by considering the spherical structure of the porous substrate.

The porous substrate may include a porous film, and the porous film may be an insulator and may have microporosity. The porous film serves to pass metal ions such as lithium ions through pores while preventing physical contact between electrodes, and any organic or inorganic porous membrane typically used as a separator in secondary batteries can be used without any particular limitation. As a specific example, the porous film is a porous polymer film, for example, a porous polymer film containing at least one selected from the group consisting of polyolefin-based resins, fluorine-based resins, polyester-based resins, polyacrylonitrile resins, and cellulose-based resins, woven fabrics , may be a nonwoven fabric or a laminated structure of two or more layers thereof, but is not limited thereto. The thickness of the porous film is generally within the range used in the field of secondary batteries, and may be, for example, 1 to 1000 μm, specifically 10 to 800 μm, but is not limited thereto.

In one embodiment, the crystalline metal salt may be located on the surface of the porous film. In this case, the surface of the porous film may include not only the outermost surface of the porous film, but also a surface with open pores (a porous surface of open pores).

The porous substrate may include a porous film; and a porous coating layer positioned on at least one surface of the porous film, or on each of both surfaces.

The porous coating layer may contain inorganic particles, organic particles, organic-inorganic composite particles, or a mixture thereof, and may have porosity due to an empty space between particles. The particulate form (inorganic particles, organic particles, organic-inorganic composite particles, or mixtures thereof) contained in the porous coating layer is not particularly limited as long as it is electrochemically stable because oxidation and/or reduction reactions do not occur in the operating voltage range of the electrochemical device. Substantially, the particulate form is usually used as a layer coated on the insulating microporous membrane to improve the heat resistance of the separator in the secondary battery, improve strength, improve wettability of the electrolyte, improve ionic conductivity, and/or enhance the degree of dissociation of salt in the electrolyte. can be used without For example, the inorganic particles may include a metal oxide, a metal carbide, a metal alloy, a metal phosphate, a metal nitride, a mixture thereof, or a composite thereof, and substantially, Al, Ti, Ba, Pb, Zr, Sr, Hf. , Li, Zn, Ce, Mg, Ca, Zn, Y, Nb, and oxides, carbides, nitrides, phosphates or alloys containing at least one element selected from the group consisting of Si, but are limited thereto not. Additionally or alternatively, the inorganic particle may be a dielectric having a dielectric constant of 5 or more, specifically 10 or more, for example, BaTiO ₃ , Pb(Zr,Ti)O ₃ (PZT), Pb _1-x La _x Zr _{1 -y} Ti _y O ₃ (PLZT, 0<x<1, 0<y<1), Pb(Mg _1/3 Nb _2/3 )O ₃ -PbTiO ₃ (PMN-PT), HfO ₂ , SrTiO ₃ , SnO ₂ , CeO ₂ , MgO, Mg(OH) ₂ , NiO, CaO, ZnO, ZrO ₂ , SiO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , AlOOH, Al(OH) ₃ , SiC and TiO ₂ or these mixtures or complexes thereof, and the like, but are not limited thereto. In addition or alternatively, the inorganic particles may be inorganic ion conductors, for example, lithium secondary batteries, which are representative examples of electrochemical devices, lithium phosphate, lithium titanium phosphate (Li _p Ti _q (PO ₄ ) ₃ , 0<p<2 , 0<q<3), lithium aluminum titanium phosphate (Li _a Al _b Ti _c (PO ₄ ) ₃ , 0<a<2, 0<b<1, 0<c<3), (LiAlTiP) _x O _y Glass series (x < 4, 0 < y < 13), lithium lanthanum titanate (Li _e La _f TiO ₃ , 0 < e < 2, 0 < f < 3), lithium germanium thiophosphate (Li _x Ge _y P _z S _w , 0 < x < 4, 0< y < 1, 0 < z < 1, 0 < w < 5), lithium nitride (Li _k N _l , 0<k<4, 0<l<2), SiS ₂ -based glass (Li _m Si _n S _o , 0<m<3, 0<n<2, 0<o<4), P ₂ S ₅ -based glass (Li _x P _y S _z , 0 < x < 3) , 0 < y < 3, 0 < z < 7), a mixture thereof, or a combination thereof, but is not limited thereto. The particle phase may have a unimodal, bimodal, or trimodal size distribution (diameter distribution), and a size in which the porosity due to the particulate void space is 20 to 80%, specifically 30 to 70%, for example, the average A diameter of the order of 10 ⁻¹ micrometers to the order of 10 ¹ micrometers is sufficient, but is not limited thereto. A porous coating layer may be positioned on one surface of the porous film or on each of two surfaces facing each other, and two or more layers different from each other at least one of a particulate material, a particle size, and a content ratio of a particulate contained in the layer are stacked may be, but is not limited thereto. The thickness of the porous coating layer may be 0.01 to 0.3 with the thickness of the porous film being 1, but is not limited thereto.

The porous coating layer may further include a binder (organic binder), and the binder may serve to bind the above-mentioned particulate to the porous film. The binder may be any polymer binder commonly used in the field of electrochemical devices, and may be either an aqueous polymer binder or a non-aqueous polymer binder. As an example of the polymer binder, polyvinylidene fluoride (PVdF), polyvinylidene fluoride-hexafluoropropylene, polyvinylpyrrolidone, polyacrylonitrile, polyvinylidene fluoride-trichloroethylene, polyvinylidene Fluoride-chlorotrifluoroethylene (PVdF-CTFE), polymethyl methacrylate, polyvinyl acetate, ethylene-co-vinyl acetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, Cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxymethyl cellulose, acrylonitrile styrene-butadiene copolymer, polyimide, polyvinyl alcohol, carboxymethyl cellulose Woods, starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene tere polymer (EPDM), sulfonated EPDM, styrene butyrene rubber, fluororubber, or a mixture thereof, but is not limited thereto. The porous coating layer may contain 5 to 50 parts by weight, specifically 10 to 40 parts by weight of the binder based on 100 parts by weight of the particulate form, but is not limited thereto.

In one embodiment, the crystalline metal salt may be located in one or more regions selected from the interface between the porous film and the porous coating layer, the inside of the porous coating layer, and the surface of the porous coating layer.

When the metal salt is positioned at the interface between the porous film and the porous coating layer, the metal salt may be substantially uniformly positioned on the interface between the porous film and the porous coating layer. It may be located selectively (partially) in a region (interface region exposed by open pores).

Together with or independently from this, a metal salt may be located inside the porous coating layer. When the metal salt is located inside the porous coating layer, the metal salt may be located on the particulate surface of the porous coating layer and/or the porous surface of the porous coating layer. The particulate surface may include a surface with pores when the particles have porosity, and the metal salt may be partially or substantially uniformly located on the particulate surface. The inside of the porous coating layer may include a porous surface inside the porous coating layer. The pore surface is a surface that partitions the pores inside the porous coating layer, and may be a surface area of a particle excluding a binder surface area, an area between particles or a contact area between particles and a binder. When the metal salt is located on the pore surface of the porous coating layer, the metal salt may be located on a part or all of the pore surface. can

Together with or independently from this, a metal salt may be located on the surface of the porous coating layer. The surface of the porous coating layer may refer to a macroscopic outermost surface. The metal salt may be located partially or substantially uniformly on the outermost surface of the porous coating layer.

As a practical example, the metal salt may be located at the interface between the porous film and the porous coating layer, the porous surface inside the porous coating layer, and the surface (outermost surface) of the porous coating layer.

As another practical example, the metal salt may be located on the surface (outermost surface) of the porous coating layer and a partial region of the inner pore surface of the porous coating layer. In this case, the partial region of the inner pore surface may mean an inner pore surface adjacent to the outermost surface, for example, 0.05 in the thickness direction of the porous coating layer from the surface (outermost surface) of the porous coating layer by setting the thickness of the porous coating layer to 1 to 0.8, 0.1 to 0.7, 0.1 to 0.6, 0.1 to 0.5, 0.1 to 0.4, or 0.1 to 0.3 may mean a pore surface positioned in a region corresponding to, but is not necessarily limited thereto.

As another practical example, the metal salt may be located on the particulate surface of the porous coating layer. That is, the particulate form of the porous coating layer may be in a state coated with a metal salt. Accordingly, the metal salt may be located in the region where the particle phase is located inside the porous coating layer, the region where the particle phase is located on the outermost surface of the porous coating layer, and the region where the particle phase is located at the interface between the porous film and the porous coating layer. According to the manufacturing method, when the metal salt is located on the particulate surface of the porous coating layer, the porous coating layer is formed by adsorbing the metal salt on the particles of the porous coating layer (after coating), and then using a slurry containing the particle phase to which the metal salt is adsorbed. case may be applicable.

The above-described example is only an example in which the metal salt of the composite separator can be smoothly supplied to the liquid electrolyte when the composite separator and the liquid electrolyte are in contact, and it goes without saying that the present invention is not limited to this embodiment.

Metal salts positioned on the surface of the porous film, the interface between the porous film and the porous coating layer, inside the porous coating layer and/or on the surface of the porous coating layer may be adsorbed and positioned in the form of molecules or clusters, but are not necessarily limited thereto.

The content of the metal salt contained in the composite separator may be determined in consideration of the concentration (injection concentration) of the liquid electrolyte injected into the electrochemical device provided with the composite separator and the desired concentration (design concentration) of the electrolyte. That is, the composite separator may contain, at least, a metal salt corresponding to the difference between the total amount of solute required for the design concentration (total number of moles) and the total amount of solute (total number of moles) contained in the liquid electrolyte to be injected. It may contain a metal salt. As a practical example, the design concentration may be at least 1.1M concentration, at least 1.3M concentration, at least 1.5M concentration, at least 1.7M concentration, at least 1.9M concentration, at least 2.0M concentration, at least 2.1M concentration, or at least 2.2M concentration, and is substantially 6.0 M concentration or less, 5.5M concentration or less, 5.0M concentration or less, 4.5M concentration or less, 4.0M concentration or less, 3.5M concentration or less, 3.0M concentration or less, or 2.5M concentration or less, but is not limited thereto. For example, the design concentration is 1.1M to 6.0M concentration, 1.3 to 5.5M concentration, 1.5 to 5.5M concentration, 1.7 to 5.5M concentration, 1.9 to 5.5M concentration, 2.0 to 5.5M concentration, 2.1 to 5.5M concentration, 2.2 to 5.5M concentration, 1.5 to 3.0M concentration, and 1.5 to 2.5M concentration. The infusion concentration may be a concentration of 0.3 to 1.0M, a concentration of 0.5 to 1.0M, or a concentration of 0.8 to 1.0M. At this time, the salt concentration in the design concentration and the injection concentration means the total concentration of the salt (electrolyte salt) of the metal ion (the metal ion participating in the electrochemical reaction) dissolved in the electrolyte. Accordingly, it goes without saying that the electrolyte salt dissolved in the injected electrolyte may be the same as or different from the metal salt provided through the composite separator. The composite separator may contain, at least, a metal salt in an amount or more capable of increasing the concentration of the liquid electrolyte from the injection concentration to the design concentration by contacting the injected liquid electrolyte.

At this time, as the wettability is a big problem in the high-concentration electrolyte, and the electrolyte injection process is difficult and takes a long time, a more effective example is a high-concentration electrolyte of 1.1 to 6.0M level, but this is one embodiment of the present invention It is only an advantageous example due to the technical advantages of the composite separator according to the example, and a conventional liquid electrolyte having a design concentration of 1M or less or 1M concentration can also be generated inside the electrochemical device by the composite separator according to an embodiment of the present invention. there is. As an extreme example, the solvent may be converted into a liquid electrolyte by the composite separator according to an embodiment of the present invention inside the electrochemical device. That is, in the electrochemical device manufacturing process, the solvent of the liquid electrolyte is added, the metal salt of the composite separator is dissolved in the injected solvent inside the electrochemical device, and the liquid electrolyte can be generated inside the electrochemical device.

As a practical and non-limiting example, in the composite separator, the metal salt content, which is the mass of the metal salt per unit area of the porous substrate, is 0.1 to 5.0 mg/cm ² , 0.2 to 4.0 mg/cm ² , 0.2 to 3.0 mg/cm ² It may be.

In one embodiment, the metal salt contained in the composite separator may be any solute (electrolyte salt) used in a liquid electrolyte in the field of electrochemical devices. Specifically, the metal salt contained in the composite separator may have a molecular weight (g/mole) of 1000 or less, specifically 500 or less, more specifically 400 or less, and may have substantially a molecular weight of 10 or more, 20 or more, or 30 or more. . In addition, in the metal salt contained in the composite separator, the number of anions per molecule of the metal salt may be 1 to 4, specifically, 1 to 3, and more specifically, 1 to 2, respectively.

As a practical example, a metal ion participating in an electrochemical reaction of an electrochemical device is used as an active ion, and a metal salt provides an active ion as a cation, Cl ^- , Br ^- , I ^- . NO ₃ ^- , N(CN) ₂ ^- , BF ₄ ^- , ClO ₄ ^- , PF ₆ ^- , (CF ₃ ) ₂ PF ₄ ^- , (CF ₃ ) ₃ PF ₃ ^- , (CF ₃ ) ₄ PF ₂ ^- , (CF ₃ ) ₅ PF ^- , AsF ₆ ^- , BF ₆ ^- , SbF ₆ ^- , (CF ₃ ) ₆ P ^- , CF ₃ SO ₃ ^- , CF ₃ CF ₂ SO ₃ ^- , AlO ₃ ^- , AlCl ₄ ^- , C ₄ F ₉ SO(CF ₃ SO ₂ ) ₂ N ^- , (CF ₃ CF ₂ SO ₂ ) ₂ N ^- , (FSO ₂ ) ₂ N ^- , (C ₂ F ₅ SO ₃ ) ₂ N ^- , (F ₃ ) CF ₂ SO ₂ ) ₂ N ^- (C ₂ F ₅ SO ₂ ) ₂ N ^- , (CF ₃ SO ₂ ) ₂ N ^- , CF ₃ CF ₂ (CF ₃ ) ₂ CO ^- , (CF ₃ SO ₂ ) ₂ CH ^- , (SF ₅ ) ₃ C ^- , (CF ₃ SO ₂ ) ₃ C ^- , CF ₃ (CF ₂ ) ₇ SO ₃ ^- , CF ₃ CO ₂ ^- , CH ₃ CO ₂ ^- , SCN ^- , B ₁₀ Cl ₁₀ ^- , C ₄ BO ₈ ^- , B(C ₂ O ₄ ) ₂ ^- , CH ₃ SO ₃ ^- , etc. may be a salt that provides an anion (counter ion of an active ion), in particular a sulfonyl group It may be a crystalline metal salt containing, but is not necessarily limited thereto. The metal salt contained in the composite separator is sufficient as long as it is a salt of an active ion required for the composition in consideration of the spherical composition of the designed liquid electrolyte. In the case of a lithium secondary battery, which is a typical electrochemical device, the active ion may be a lithium ion.

As described above, in the process of intensifying research on a composite separator that acts as an electrolyte salt source and increases the concentration of a liquid electrolyte injected inside an electrochemical device, the present applicant has a specific metal salt, specifically, containing a sulfonyl group. In the case of a metal salt (a crystalline metal salt containing a sulfonyl group), it was confirmed that a high degree of flame retardancy was imparted to the porous substrate, and it was confirmed that the electrochemical properties were greatly improved along with this flame retardancy. In order to commercialize mid-to-large electrochemical devices, safety to prevent explosion and ignition must be prioritized above all else. The present applicant has confirmed that such safety is firmly secured by a metal salt containing a sulfonyl group (a crystalline metal salt containing a sulfonyl group). After acting as a salt source to a liquid electrolyte in an electrochemical device, a high concentration of a sulfonyl group-containing crystalline metal salt formed relatively high in the separation membrane (porous substrate), and also by a different material, a sulfonyl group-containing crystalline metal salt is separated into a separation membrane It was confirmed that this safety (flame retardancy) was implemented even when fixed to (porous substrate).

Based on these findings, a composite separator according to an embodiment of the present invention includes a porous substrate; and a crystalline metal salt containing a sulfonyl group (a crystalline metal salt containing a sulfonyl group). The flame retardancy is ensured by the sulfonyl group-containing crystalline metal salt, and at the same time, the electrochemical properties may not be deteriorated, or the electrochemical properties may be improved.

Although not necessarily limited to this interpretation, the crystalline metal salt containing a sulfonyl group fixed to the porous substrate by a different material, located on the porous substrate in the state of a salt (crystalline salt) without dissociation into ions, or self-immobilized is , a coordination structure is formed by the interaction between the active cation and solvent molecules of the liquid electrolyte injected into the electrochemical device and the sulfonyl groups of the anions, so that the solvent molecules with very high volatility and at the same time become a free solvent By suppressing the occurrence of flame retardancy, it is possible to impart flame retardancy to the porous substrate. In particular, when the solvent of the liquid electrolyte contains a carbonate-based solvent, an ether-based solvent, or a carbonate-based and ether-based solvent, two to three or more active metal cations (active ions) and a sulfonyl group and a group clustering of solvent molecules ( aggregate clusters) may be accelerated, making it easier to form coordination structures.

Furthermore, while flame retardancy is firmly secured by the sulfonyl group-containing crystalline metal salt, ion conduction performance through the porous substrate can be greatly improved. Although not necessarily limited to this interpretation, a locally high concentration ion cluster is formed according to the crystalline metal salt provided by the composite separation membrane, so that the movement of ions near the inside of the cluster occurs smoothly following the Grotthuss mechanism. coefficient can be improved. Furthermore, the ionic conductivity of metal ions can be improved by accelerating the movement of metal ions through a synergistic effect with the vehicle mechanism by solvent molecules.

It is preferable that the sulfonyl group-containing crystalline metal salt be substantially uniformly positioned on the surface region of the porous substrate so that the flame retardancy may be stably exhibited. Thus, as an advantageous example in consideration of the flame retardancy, the sulfonyl-containing metal salt is substantially uniformly located on the surface (outermost surface) of the porous substrate, or the total thickness of the porous substrate is t _pm , and 0.05 in the thickness direction of the porous substrate from one surface It can be located substantially uniformly in the surface area, which is a region from up to 0.3 t _pm .

As a practical example, when the porous substrate includes a porous film without a separate coating layer, the crystalline metal salt containing a sulfonyl group may be substantially uniformly positioned on the surface of the porous film.

As a practical example, when the porous substrate includes a porous film and a porous coating layer positioned on at least one surface of the porous film, the sulfonyl group-containing crystalline metal salt is substantially uniformly positioned on the surface (outermost surface) of the porous coating layer, or Alternatively, the sulfonyl group-containing crystalline metal salt is substantially uniformly located on the surface (outermost surface) of the porous coating layer and the inner partial region of the porous coating layer, or the surface of the porous coating layer (outermost surface), the interior (internal pores) of the porous coating layer surface) and at the interface between the porous film and the porous coating layer may be substantially uniformly positioned in a region in contact with the pores of the porous coating layer. In this case, a portion of the inner portion of the porous coating layer in which the sulfonyl group-containing crystalline metal salt is located is similar to or the same as described above.

However, this example is only an advantageous example that can stably impart flame retardancy to a porous substrate, and the present invention provides a specific position of the sulfonyl group-containing crystalline metal salt, and furthermore, the flame retardancy is provided by the sulfonyl group-containing crystalline metal salt. Of course, it cannot be limited. As will be described later in relation to the coating solution, by locating a sulfonyl group-containing crystalline metal salt on each of all the constituent members in direct contact with the liquid electrolyte in the electrochemical device, flame retardancy can be imparted to the corresponding constituent member.

In the composite separator according to an embodiment, the sulfonyl group-containing crystalline metal salt may have a molecular weight (g/mole) of 1000 or less, specifically 500 or less, more specifically 400 or less, and substantially 10 or more, 20 or more, or It may have a molecular weight of 30 or more. In addition, in the sulfonyl group-containing crystalline metal salt, the number of anions per molecule of the metal salt may be 1 to 4, specifically, 1 to 3, and more specifically, 1 to 2, respectively.

In the composite separator according to an embodiment, the sulfonyl group-containing crystalline metal salt may be any one or two or more selected from compounds satisfying the following Chemical Formulas 1 to 4. When the composite separator contains a compound satisfying the following Chemical Formulas 1 to 4, flame retardancy is ensured, wettability to the liquid electrolyte can be improved, and a smoother ion flow can be caused.

(Formula 1)

In Formula 1, A ⁺ is a monovalent cation, R ₁ is F, CFH ₂ , CF ₂ H, or C _n F _2n+1 , where n is a natural number of 1 or more, specifically 1 to 5, more specifically 1 to It is a natural number of 3.

(Formula 2)

In Formula 2, A ²⁺ is a divalent cation, and R ₁ is F, CFH ₂ , CF ₂ H or C _n F _2n+1 , where n is a natural number of 1 or more, specifically 1 to 5, more specifically 1 to 3 is a natural number.

(Formula 3)

In Formula 3, A ⁺ is a monovalent cation, R ₁ and R ₂ are each independently F, CFH ₂ , CF ₂ H or C _n F _2n+1 , where n is a natural number of 1 or more, specifically, a natural number of 1 to 5 , more specifically, a natural number from 1 to 3.

(Formula 4)

In Formula 4, A ²⁺ is a divalent cation, R ₁ and R ₂ are each independently F, CFH ₂ , CF ₂ H, or C _n F _2n+1 , where n is a natural number of 1 or more, specifically 1 to 5 It is a natural number, more specifically, a natural number from 1 to 3.

In Formulas 1 to 4, A ⁺ or A ²⁺ may be a monovalent metal ion or a divalent metal ion capable of serving as a counterpart of the sulfonyl group-containing anion component. As a non-limiting example, the monovalent cation may be an ion of one or more metals selected from alkali metals, for example, lithium ion or sodium ion, and the divalent cation may be one or more selected from alkaline earth metals and transition metals. of ions, for example, zinc ions, etc., but is not necessarily limited thereto. Together or independently thereof, in Formulas 1 to 4, R ₁ and R ₂ may each independently be selected from F, CF ₃ and CF ₂ CF ₃ . As a practical example, the sulfonyl group-containing crystalline metal salt is lithium trifluoromethanesulfonate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(perfluoroethane) Sulfonyl) imide, zinc trifluoromethane sulfonate, zinc di [bis (trifluoromethyl sulfonyl) imide] may be any one or two or more selected from the like.

Monovalent cations or divalent cations in Formulas 1 to 4 participate in the electrochemical reaction of the electrochemical device so that the conductivity of ions moving between the electrode zones through the composite separator can be improved more significantly with the improvement of wettability It may be an active ion, which is a metal ion. In the case of a lithium secondary battery, which is an example of a typical electrochemical device, the sulfonyl group-containing crystalline metal salt may be at least one material selected from compounds satisfying Chemical Formulas 1 and 3, and in this case, the monovalent cation may be a lithium ion. there is.

In terms of securing flame retardancy by the above-described sulfonyl group-containing crystalline metal salt and further stably improving wettability and/or ionic conductivity, the crystalline metal salt may be in a state of being fixed to the porous substrate by a different material from the metal salt. there is.

However, the fixation of the metal salt cannot be interpreted as being limited to the case of the sulfonyl group-containing crystalline metal salt. As described above, even when the composite separator acts as a metal salt source for the liquid electrolyte, the metal salt may be fixed to the porous substrate by an external element (a heterogeneous material) other than the porous substrate and the metal salt. However, in consideration of the function as a salt source, fixation by an external element (a dissimilar material) is eliminated in a state in which the composite separator is in contact with the liquid electrolyte, and the metal salt is an external element (a dissimilar material) capable of dissolving the metal salt into the liquid electrolyte. can be fixed. Accordingly, based on the non-contact state with the liquid electrolyte, the metal salt provided as a solute of the electrolyte in the composite separator may also be in a state fixed to the porous substrate.

However, in the case of a crystalline metal salt containing a sulfonyl group, the fixation of the metal salt also includes fixation in which the fixation by a dissimilar material is maintained (maintaining a state in which the metal salt cannot be freely dissolved into the liquid electrolyte) even in contact with the liquid electrolyte. should be interpreted as

Specifically, the metal salt (including the crystalline metal salt containing a sulfonyl group) may be in a fixed state by at least one binding component selected from a linear polymer and a cross-linked polymer. When the binding component is a linear polymer or a cross-linked polymer, the activity against Brownian motion is suppressed, and the designed concentration of the metal salt in the composite membrane can be firmly maintained, thereby stably securing the desired physical properties for a long period of time.

As a practical example, linear polymers include polyvinylidene fluoride (Poly(vinylidene fluoride), PVdF), polyvinylidene fluoride hexafluoropropylene (Poy(vinylidene fluoride)-co-hexafluoropropylene, PVdF-co-HFP), Polymethylmethacryalte (PMMA), polystyrene (PS), polyvinylacetate (PVA), polyacrylonitrile (PAN), polyethylene oxide (PEO), polyacetylene (Polyacetylene), polythiophene (polythiophene), polypyrrole (polypyrrole), poly (p-phenylene) (poly (p-phenylene)), polyphenylene vinylene (poly (phenylenevinylene)), poly (phenylene sulfide) (poly(phenylenesulfide)), polyaniline, and polyethylenedioxythiophene (poly(3,4-ethylenedioxythiophene); PEDOT) may be any one or a mixture of two or more selected from, but are not limited thereto.

When the binding component is a cross-linked polymer, it is advantageous because the desired physical properties can be more uniformly imparted to the desired portion of the porous substrate. Specifically, when the binding component is a cross-linked polymer, the metal salt can be fixed by curing a curing component having hardenability, which is converted into a binding component by curing, in a mixed state with the metal salt (in the presence of the metal salt).

For example, the curing component may be one or two or more selected from the group of monomers, oligomers, and prepolymers having curing ability. In this case, curing of the curable ability may be thermal curing, chemical curing, and/or photocuring, but is not limited thereto. Substantially, the curing component may be a monomer having a curable ability (a crosslinkable monomer), and the binding component may be a crosslinking polymer. More substantially, the fixation of the metal salt may be achieved by crosslinking the crosslinkable monomer by an initiator in a state in which the metal salt and the crosslinkable monomer are mixed.

Specifically, the cross-linkable monomer as a curing component may be a monomer having two or more functional groups or a mixed monomer in which a monomer having two or more functional groups and a monomer having one functional group are mixed, but the present invention is a cross-linkable monomer Of course, it cannot be limited by the number of functional groups. As a practical example, the crosslinkable monomer that forms a crosslinked polymer by crosslinking is any one or two or more selected from acrylate-based monomers, acrylic acid-based monomers, sulfonic acid-based monomers, phosphoric acid-based monomers, perfluorinated monomers, and acrylonitrile-based monomers. It may be a crosslinkable monomer, but is not limited thereto. As a practical example of the monomer having two or more functional groups, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, trimethylolpropane ethoxylate triacrylate, Any one or a mixture of two or more selected from trimethylolpropane ethoxylate trimethacrylate, bisphenol ethoxylate diacrylate, bisphenol ethoxylate dimethacrylate, etc., but is not limited thereto. As a practical example of the monomer having one functional group, methyl methacrylate, ethyl methacrylate, butyl methacrylate, methyl acrylate, butyl acrylate, ethylene glycol methyl ether acrylate, ethylene glycol methyl ether methacrylate, acrylo Any one or a mixture of two or more selected from nitrile, vinyl acetate, vinyl chloride and vinyl fluoride may be mentioned, but the present invention is not limited thereto. In a more practical example, the crosslinkable monomer is trimethylolpropane ethoxylate triacrylate alone or trimethylolpropane ethoxylate triacrylate; and other monomers having two or more functional groups and monomers having one functional group. It may include a mixture of any one or more; but is not limited thereto.

The composite separator according to an embodiment may contain a crystalline metal salt in the form of a coating layer.

Specifically, the composite separator includes a porous substrate; and a coating layer positioned on at least one surface of the porous substrate and containing the above-described crystalline metal salt. More specifically, the composite separator may include a porous substrate; and a coating layer located on at least one surface of the porous substrate and comprising the above-described crystalline metal salt and at least one polymer component selected from the above-mentioned linear polymer and cross-linked polymer. The coating layer may correspond to a case in which the binding component for fixing the metal salt forms a continuously connected continuum, but it cannot necessarily be interpreted as being limited to this case. Regardless of whether or not a continuum of the binder component is formed, in a manufacturing method, a solution (coating solution) containing a metal salt and a binder or curing component is uniformly applied to a desired surface area of the porous substrate, and then at least the solvent is volatilized and removed , when a curing process is performed, if necessary, so that when a metal salt and a binding component coexist in a desired portion of the porous substrate, it can be interpreted that the metal salt is provided in the form of a coating layer. At this time, the solvent used is at least one selected from C1-C3 lower alcohol solvents, ketone solvents, and carbonate solvents in which the above-described metal salts, linear polymers and crosslinked polymers are easily dissolved and complete volatilization is removed by simple drying. A solvent is preferred. Examples of the C1-C3 lower alcohol solvent include methanol, ethanol, and isopropyl alcohol. Examples of the ketone solvent include acetone, methyl ethyl ketone, and methyl isobutyl ketone. Examples of the carbonate solvent include ethylene carbonate. , propylene carbonate, fluoroethylene carbonate, dimethyl carbonate, diethyl carbonate, and the like. At this time, the coating solution is a liquid raw material (based on room temperature) used in the preparation of the coating solution, and is selected from the group of monomers, oligomers, and prepolymers having curing ability, and is selected from the group consisting of curing components that are converted into binding components by curing. It may contain only a solvent, and after drying in which the solvent is removed by volatilization, a solid coating film can be prepared.

The coating layer may be located on at least one surface of the porous substrate (electrode side, which is the positive electrode side or the negative electrode side), each of two surfaces facing each other of the porous substrate, or the entire surface of the porous substrate, but is not limited thereto, and the present invention is not limited thereto. It does not exclude the case where the coating layer is selectively located in a predetermined area on one surface of the porous substrate.

Specifically, the coating layer may be located on the surface (outermost surface) of the porous substrate, or located on the outermost surface of the porous substrate and the pore surface of the open pores of the porous substrate. More specifically, by taking the total thickness of the porous substrate as t _pm , it can be located on the pore surface existing in the region (surface region) from one surface (outermost surface) to 0.05 to 0.3 t _pm in the thickness direction of the porous substrate. . When the coating layer is also located on the pore surface, the size of the pores in the surface region may be partially reduced, but the pores may not be closed (damaged) and the pore structure inherent to the porous substrate may be substantially maintained as it is. In terms of maintaining the inherent pore structure of the porous substrate, it is preferable that the coating layer contains a crosslinking molecule. This is because, when the coating layer is formed using a liquid containing a crosslinkable monomer and a metal salt, the coating layer can be formed extremely thinly and uniformly on the outermost surface of the porous substrate or on the outermost surface and the pore surface of the porous substrate. This is because damage to the structure can be prevented.

As a practical example, when the porous substrate includes a porous film that is not provided with a separate coating layer, the coating layer may be located directly bound to the surface of the porous film. Methodologically, the direct binding is due to the phase transformation (solidification) of the binding component by volatilization and removal of the solvent after application of the liquid (coating solution) containing the metal salt and the binding component and/or the curing component and/or hardening of the curing component. can

As a practical example, when the porous substrate includes a porous film and a porous coating layer positioned on at least one surface of the porous film, the coating layer (metal salt-containing coating layer) is located directly bound to the surface (outermost surface) of the porous coating layer, or or the surface (outermost surface) of the porous coating layer and the pore surface belonging to the inner partial region (surface region) of the porous coating layer are located directly bound to, or the surface of the porous coating layer (outermost surface), the interior of the porous coating layer (internal pores) surface) and at the interface between the porous film and the porous coating layer may be located directly bound to the region in contact with the pores of the porous coating layer. Together or independently of this, a coating layer (a coating layer containing a metal salt) may be positioned between the porous film and the porous coating layer. At this time, the inner partial region (surface region) of the porous coating layer in which the coating layer is located is similar to or the same as described above.

When the metal salt is provided in the form of a coating layer, the composite separator is 5 to 70, 5 to 50, 5 to 40, 5 to 30, 10 to 25 parts by weight of a heterogeneous material, specifically a binding component, more specifically, based on 100 parts by weight of the metal salt. It may include one or more polymers selected from linear polymers and crosslinked polymers. The content of such a heterogeneous material is an amount capable of stably fixing the metal salt contained in the composite separator.

When the metal salt is provided in the form of a coating layer, 0.3 mg/cm ² or more per unit area of the porous substrate is preferable so that the composite separator can exhibit a solid flame retardancy even when in direct contact with a flame. Specifically, the metal salt content is 0.3 to 5.0 mg/cm ² , 0.3 to 4.0 mg/cm ² , 0.3 to 3.0 mg/cm ² , 0.3 to 2.5 mg/cm ² , 0.3 to 2.0 mg/cm ² , It may be 0.4 to 1.5 mg/cm ² , 0.5 to 1.4 mg/cm ² , or 0.5 to 1.2 mg/cm ² .

Together or independently, the projected image metal salt content, which is the mass of the metal salt per unit area based on the projected image of the porous substrate, is 0.3 to 6.0 to ensure flame retardancy and to prevent deterioration of the properties of the electrochemical cell due to the introduction of the metal salt in the form of a coating layer. mg/cm ² , specifically 0.3 to 5.0 mg/cm ² , 0.3 to 4.0 mg/cm ² , specifically 0.5 to 3.0 mg/cm ² , 0.4 to 2.0 mg/cm ² , 0.5 to 1.5 mg/cm ² , 0.7 to 1.4 mg/cm ² , 0.8 to 1.3 mg/cm ² , or 0.8 to 1.2 mg/cm ² may be.

In this case, in the projection image metal salt content, the unit area may be a unit area on a projection image in a direction looking down on the widest surface of the porous substrate, and the mass of the metal salt per unit area is the porosity corresponding to the unit area of the projected image. It may be the total mass of metal salts located in the substrate region. For example, when two opposite surfaces of the porous substrate are first and second surfaces, the mass of the metal salt per unit area of the first surface is A, and the mass of the metal salt per unit area of the second surface is B, the metal salt content is A or B, and the projected metal salt content is A+B. In this case, it goes without saying that the metal salt content in each of the different surfaces may satisfy each of the above-described ranges.

When a metal salt, advantageously a crystalline metal salt containing a sulfonyl group is introduced in the form of a coating layer, the composite separator provided in the electrochemical device can stably exhibit flame retardancy even in a harsh environment, and the change in physical properties during the life expectancy of the electrochemical device It can stably exhibit flame retardancy without Even when one or more sulfonyl group-containing crystalline metal salts selected from compounds satisfying the above formulas 1 to 4 are introduced in the form of a coating layer, excellent wettability and / Alternatively, improved metal ion conductivity may be maintained. Accordingly, it goes without saying that whether or not to fix the metal salt may be selectively determined in consideration of the specific use of the electrochemical device and important properties required for the use.

As described above, the composite separator according to one embodiment of the present invention may contain a metal salt (first metal salt) serving as a salt source for the electrolyte, and the composite separator according to another embodiment is a solid and long-term stable flame retardant It may contain a sulfonyl group-containing crystalline metal salt (second metal salt) in a fixed state to the porous substrate in order to secure it. In this case, the present invention cannot be interpreted as being limited to the case of a metal salt serving as a salt source or a crystalline metal salt containing a sulfonyl group in a fixed state. That is, the composite separator according to the present invention comprises: a porous substrate; and a metal salt (first metal salt) serving as a salt source and a crystalline metal salt containing a sulfonyl group fixed to a porous substrate (second metal salt), respectively. As an example, a coating layer containing a crystalline metal salt containing a sulfonyl group is provided on the surface (or surface region) of the porous substrate to ensure flame retardancy, and a form soluble in contact with a liquid medium on a porous substrate having a coating layer containing a metal salt As a first metal salt is provided and may act as a salt source. A person skilled in the art in the field of electrochemical devices or separation membranes can use the action of the salt source or the imparting of flame retardancy by the crystalline metal salt containing a sulfonyl group fixed in the form of a coating layer, etc. Various modifications can be easily derived as in an example so that the physical properties of fire and flame retardancy can be simultaneously implemented, which is a level of easy change based on the above-described contents of the composite separator, and is included in the scope of the present invention.

The flame retardancy secured by the metal salt is different from the flame retardancy secured by the conventionally developed thermal stability improvement by introduction of a flame retardant material (for example, introduction of an inorganic coating layer) or a spherical material of a porous substrate. Although not necessarily limited to this interpretation, the flame retardancy implemented in the composite separator according to an embodiment of the present invention is a change in the state of a solvent molecule of a liquid electrolyte by a crystalline metal salt containing a sulfonyl group (eg, formation of a coordination structure with a metal salt) ) and/or may be flame retardant secured through suppression of free solvent by high concentration of the liquid electrolyte in contact with the separator. At this time, of course, the high concentration of the liquid electrolyte in contact with the separator may mean high concentration that occurs when a concentration gradient of the electrolyte salt between the separator and the electrode is formed by the metal salt supplied from the separator. Accordingly, the metal salt capable of exhibiting flame retardancy cannot be interpreted as being limited to a sulfonyl group-containing crystalline metal salt. That is, even for a metal salt that does not contain a sulfonyl group, the metal salt is supplied from the separator to the liquid electrolyte and a high concentration of electrolyte gradient is formed toward the separator, thereby suppressing the free solvent and exhibiting flame retardancy. However, when a high-concentration electrolyte gradient is formed by the crystalline metal salt containing a sulfonyl group compared to other metal salts, the ion conductivity through the separator is greatly improved, so capacity retention, high rate characteristics, high temperature characteristics, and/or cycle characteristics can be improved. Do. Therefore, even when the metal salt contained in the composite separator is provided in a soluble form in the liquid medium and acts as a salt source to the electrolyte inside the electrochemical device, the metal salt contained in the composite separator is a sulfonyl group-containing crystalline metal salt. Advantageous, but not necessarily limited thereto.

Accordingly, the present invention provides a flame retardant separator based on the specific technical idea of the present invention.

The flame-retardant separator (flame-retardant separator I) according to the present invention is recovered after being impregnated in the following reference electrolyte for 1 minute, and immediately after recovery, when placed so that the direction of gravity and the in-plane direction of the separator are parallel to each other, from the separator for 1 minute When the following flame retardancy test is performed at a point in time when the droplet does not fall to the floor, it has a flame retardancy that does not generate a flame from the separator.

Reference electrolyte: a mixed solvent in which ethylene carbonate and dimethyl carbonate are mixed in a volume ratio of 1:1, lithium salt of LiPF ₆ , LiPF ₆ concentration of 1M, temperature of 25°C ± 5°C.

Flame-retardant test: length of flame in the air = 5 to 10 cm, flame tip temperature = 1000 to 1500 ° C., when flame is applied to the separator, the length of the flame region that is not in contact with the separator = 50 to 80% of the length of the flame in the air, the flame moving speed in contact with the separator = 1 to 5 cm/sec.

At this time, the flame movement may be a movement such that 30 to 90% of the diameter is in contact with the flame along the diameter (maximum diameter) passing through the center of the separator, and when the flame is moved, the flame is in contact with The region may be repeatedly contacted 1 to 2 times, but is not necessarily limited to such flame movement and contact.

At this time, the flame does not occur from the separation membrane means that other flames other than the flame applied from the outside for the flame retardancy test do not occur, and the flame applied from the outside is removed and there is no flame in the separation membrane almost at the same time it means

At this time, the flame retardancy test can be performed by placing the separator on the bottom of the flame retardant container at the time of the test, and the shortest separation distance between the separator and the flame applied from the outside is 0.5 cm or more, 1 cm or more, 5 cm or more, substantially 10 cm or more. The flame may be considered removed, but is not necessarily limited thereto.

The flame retardancy shown in the flame retardancy test using the above-described reference electrolyte may be the flame retardancy of the composite separator, specifically, the composite separator containing a crystalline metal salt containing a sulfonyl group. The flame retardancy test using the above-described reference electrolyte may be in a state before the composite separator is used as a separator of an electrochemical device, in a state in use, or in a state after use. As a practical example, the flame retardancy test using the above-described reference electrolyte may be in a state before the composite separator is used as a separator of an electrochemical device, that is, in a state in which there is no history of contact between the composite separator and the liquid electrolyte. As another practical example, in the flame retardancy test using the above-described reference electrolyte, a separator previously provided (used) in the electrochemical device may be separated and recovered.

Independently of this, when the separator is already provided in an electrochemical device using any liquid electrolyte, the flame-retardant separator according to the present invention (flame-retardant separator II) is a separator obtained according to the following steps when tested by the following flame retardancy test, It has flame retardancy that does not cause flames from the separation membrane.

Steps: 1) close the sealing of the electrochemical element to open at least one end, and cut the connection between the tab provided for electrical connection with the outside and the electrode complex of the anode-separator-cathode to recover the electrode complex; 2) separating and recovering only the separator from the recovered electrode complex; 3) Immediately after recovery of the separator, the direction of gravity and the in-plane direction of the separator are placed so that they are parallel, and the following flame retardancy test is performed at the time point (the first time point) when the droplet does not fall from the separator to the floor for 1 minute

Flame-retardant test: length of flame in the air = 5 to 10 cm, flame tip temperature = 1000 to 1500 ° C., when flame is applied to the separator, the length of the flame region that is not in contact with the separator = 50 to 80% of the length of the flame in the air, the flame moving speed in contact with the separator = 1 to 5 cm/sec. At this time, the flame movement may be a movement such that 30 to 90% of the diameter is in contact with the flame along the diameter (maximum diameter) passing through the center of the separator, and when the flame is moved, the flame is in contact with The region may be repeatedly contacted 1 to 2 times, but is not necessarily limited to such flame movement and contact.

The above-described flame-retardant separator (I, or II) may contain the above-described sulfonyl group-containing crystalline metal salt, and may exhibit flame retardancy by the above-described sulfonyl group-containing crystalline metal salt. Accordingly, the above-described flame-retardant separation membrane includes all of the above-described contents related to the crystalline metal salt containing a sulfonyl group in the composite separation membrane.

Alternatively, the above-described flame-retardant separator (I, or II) is flame retardant by suppressing free solvent by concentration gradient of an electrolyte salt formed by a metal salt provided to the liquid electrolyte through the composite separator, specifically, high concentration of the liquid electrolyte adjacent to the separator can indicate Accordingly, the above-described flame-retardant separation membrane may include all of the above-mentioned contents related to the composition acting as a salt source in the composite separation membrane.

Alternatively, the flame-retardant separation membrane (I, or II) described above is provided in a soluble form upon contact with a liquid medium containing a sulfonyl group-containing crystalline metal salt (second metal salt) fixed and positioned on the porous substrate and a solvent on the porous substrate. Flame retardancy can be exhibited by all of the metal salts (first metal salts) to be used.

The above-described composite separator or flame-retardant separator may be a separator that does not contain a liquid component, that is, a dry separator. For dry separation membranes, the mass of the composite membrane immediately after production is W0, and after the composite membrane is left for 1 hour immediately after production at 25° C., the mass of the composite membrane is W1h, and the mass reduction rate is (W0-W1h)/W0 x 100 (%) may mean 1% or less, specifically 0.5% or less, substantially 0%. In this case, substantially 0% means that there is no change in mass within the measurement error range of the equipment for measuring the mass, taking into account the measurement error.

The present invention includes an electrochemical device including the composite separator described above.

The present invention includes an electrochemical device including the flame-retardant separator (I, or II) described above.

Independently, the present invention provides a positive electrode; cathode; a separator interposed between the anode and the cathode; and an electrolyte, and includes an electrochemical device having a different concentration of a metal salt-derived element component, which is an element component derived from a metal salt, during component analysis of an electrode, which is an anode or a cathode; and a separator.

At this time, the phenomenon in which the concentration of the element component derived from the metal salt relatively higher than that of the electrode appears in the separator is a metal salt fixed to the separator (corresponding to the composite separator described above), specifically, in the composite separator provided in the electrochemical device. can be implemented by The metal salt according to an advantageous embodiment may be the above-mentioned sulfonyl group-containing crystalline metal salt, and the difference in concentration of element components derived from the metal salt may be due to the sulfonyl group-containing crystalline metal salt fixed and positioned on the porous substrate.

Independently, the present invention provides a positive electrode; cathode; a separator interposed between the anode and the cathode; and an electrolyte containing a metal salt; and includes an electrochemical device having a different concentration of an element component derived from a metal salt, which is an element component derived from a metal salt, during component analysis of an electrode, which is an anode or a cathode, and a separator. Practically, the concentration of the element component derived from the metal salt in the separator may be higher than the concentration of the element component derived from the metal salt in the electrode.

According to an example, the phenomenon in which the concentration of the element component derived from the metal salt is relatively higher than that of the electrode in the separator may be realized when the metal salt dissolved in the electrolyte originates from the separator. In detail, the phenomenon in which the concentration of element components derived from metal salts is relatively higher than that of the electrode in the separator contains a metal salt that can be dissolved (in a soluble form) in the electrolyte when the separator is in contact with the electrolyte, so that the electrolyte is derived from the separator It can be implemented when it contains one metal salt.

When the separator contains a metal salt in a soluble form in the electrolyte, even after providing the metal salt as a solute (electrolyte salt) by contacting the liquid medium containing the liquid electrolyte or solvent injected in the manufacturing process, the concentration of the metal salt in the porous substrate is It can be maintained for a long time in a relatively high state compared to the cathode and the anode. According to the concentration gradient formed by the metal salt derived from the separator, the electrolyte components in the separator, the anode, and the anode have different surface tensions, The concentration may be maintained for a long time in a relatively high state compared to the anode and the cathode. Due to this concentration gradient, a relatively higher concentration of elemental components derived from metal salts may appear in the separator than in the electrode.

Furthermore, when the metal salt is a metal salt containing a sulfonyl group, the surface wetting property of the separator may be greatly improved by the interaction between the sulfonyl group, active metal ions, and the solvent in the electrolyte. Accordingly, when the metal salt is a metal salt containing a sulfonyl group, the concentration difference between the concentration of the metal salt-derived element component on the surface of the separator and the concentration of the metal salt-derived element component on the electrode surface may be greater.

As described above, even when the separator contains a metal salt (including a crystalline metal salt containing a sulfonyl group) in a form soluble in the electrolyte so that an electrolyte of a desired concentration can be prepared inside the electrochemical device, it is significantly separated from the electrode There may be a difference in the concentration of the element component derived from the interlayer metal salt.

At this time, the electrolyte, specifically the liquid electrolyte, may contain one, two, three, or four or more metal salts as a solute, and the metal salt (electrolyte salt, solute) of the electrolyte is a metal salt derived from the separation membrane (hereinafter, the third metal salt) or a metal salt derived from the separator (hereinafter referred to as the tertiary metal salt) and a metal salt not derived from the separator (a metal salt pre-contained in the electrolyte injected from the outside when assembling an electrochemical device, hereinafter referred to as the fourth metal salt) may contain.

For example, the electrolyte may contain only the tertiary metal salt. In this case, a solvent that does not contain an electrolyte salt (which may contain a known additive component if necessary) may be added from the outside when assembling the electrochemical device.

As another example, the electrolyte contains a third metal salt and a fourth metal salt, and the third metal salt and the fourth metal salt may be the same type of metal salt. When the third metal salt and the fourth metal salt are the same type of metal salt (eg, metal salt A), the metal salt in the electrolyte in the electrochemical device after assembly of the electrochemical device compared to the concentration of metal salt A in the electrolyte input during the assembly of the electrochemical device A concentration may be higher.

As another example, the electrolyte contains a third metal salt and a fourth metal salt, and the third metal salt and the fourth metal salt may be different types of metal salts. When the third metal salt and the fourth metal salt are different kinds of metal salts, the electrolyte in the electrochemical device after assembly of the electrochemical device compared to the concentration of the metal salt (electrolyte salt) (the concentration of the fourth metal salt) in the electrolyte input during the assembly of the electrochemical device The total metal salt (electrolyte salt) concentration (the sum of the third and fourth metal salt concentrations) may be higher in may contain.

Independently, the present invention provides a positive electrode; cathode; a separator interposed between the anode and the cathode; and an electrolyte containing a metal salt; including, an electrode that is an anode or a cathode; and a separator; the concentration of the element component derived from the metal salt, which is an element component derived from the metal salt, is different, and the concentration of the element component derived from the metal salt in the electrode is different An electrochemical device having a concentration higher than the concentration of the element component derived from the metal salt in the separation membrane is included.

A case in which the metal salt dissolved in the electrolyte originates from the electrode (anode or cathode) and the concentration difference of the elemental component derived from the metal salt between the electrode surfaces in the electrode occurs will be described in more detail. According to an example, the phenomenon in which the concentration of the element component derived from the metal salt is relatively higher than that of the separator in the electrode may be realized when the metal salt dissolved in the electrolyte originates from the electrode. In detail, the phenomenon in which the concentration of the element component derived from the metal salt is relatively higher than that of the separator in the electrode is that the electrode contains a metal salt that can be dissolved (in a soluble form) in the electrolyte when in contact with the electrolyte, so that the electrolyte is derived from the electrode It can be implemented when it contains one metal salt.

In this case, in the above-described composite separator, the porous substrate may correspond to the electrode active material layer (negative electrode active material layer or positive electrode active material layer) of the electrode, and the surface or surface area of the electrode active material layer may correspond to the surface or surface area of the porous substrate. can Accordingly, the electrochemical device in which the concentration of the element component derived from the metal salt in the electrode is higher than the concentration of the element component derived from the metal salt in the separation membrane replaces the porous substrate with the electrode active material layer in the composite separator described above, and all of the above-described elements in the composite separator include content.

In an embodiment, the electrode may contain the metal salt in a form soluble in a liquid medium including a solvent or in a fixed form. That is, the metal salt may be adsorbed and/or fixed to the electrode active material layer. Substantially, it may contain a metal salt located in a portion or the entire region of the electrode active material layer (the negative electrode active material layer and/or the positive electrode active material layer).

A partial region of the electrode active material layer may mean a surface area of the electrode active material layer, and the surface area of the electrode active material layer is 0.05 to 0.3 in the direction of the current collector from the side surface in contact with the electrolyte, with the thickness of the electrode active material layer being t _am It may mean a region up to _am , but is not necessarily limited thereto.

When located in the entire area of the electrode active material layer, the metal salt is a pore area due to pores (substantially open pores) inside the electrode active material layer, a particulate active material surface (negative electrode active material surface or positive electrode active material surface) area of the electrode active material layer, It may be located in both the pore area and the active material surface area, but is not limited thereto.

As a manufacturing method, a metal salt may be supported or fixed in some or all regions of the electrode active material layer by applying a coating solution to be described later on the electrode active material layer. Alternatively, as a manufacturing method, after coating a metal salt on the electrode active material particles, the electrode active material layer is prepared using the electrode active material coated with the metal salt, so that the metal salt can be supported on the entire area of the electrode active material layer. On the other hand, by adding a metal salt to an electrode slurry containing an electrode active material, a binder, and, if necessary, a conductive material, and applying the electrode slurry containing the metal salt to prepare an electrode active material layer, the metal salt is supported on the entire area of the electrode active material layer. can

Experimentally, the concentration of the element component derived from the metal salt in the electrode and the separator may be measured by the following analysis method by following step (II) and/or step (III). The following steps (II) and/or step (III) are steps capable of excluding the influence of the charging or discharging state or the immediately preceding use state of the electrochemical device.

Step (II): 1) Close the sealing of the electrochemical element to open at least one end, and cut the connection between the tab provided for electrical connection with the outside and the electrode complex of anode-separator-cathode to separate and recover the electrode complex ; recovering the electrode composite molded in the epoxy resin by curing the recovered electrode composite at 60°C for 24 hours or more using an epoxy resin for molding; A sample obtained by cutting a molded electrode composite into a cross-sectional specimen within 20 μm in thickness using an ion beam was analyzed by neutron depth profiling to calculate the concentration gradient for active metal ions in the cross-section of the electrode composite.

Step (III): 1) Close the sealing of the electrochemical element, open at least one end, and cut the connection between the tab provided for electrical connection with the outside and the electrode complex of anode-separator-cathode to separate and recover the electrode complex ; 2) In the recovered electrode complex, a solution in which the separator, the positive electrode, and the negative electrode were each immersed in anhydrous deuterated dimethyl sulfoxide for 24 hours was analyzed by the following method.

Analysis methods: F-NMR (Florine Nuclear Magnetic Resonance Spectroscopy), Cl-NMR (Chlorine Nuclear Magnetic Resonance Spectroscopy), ICP-MS (Inductively Coupled Plasma Mass Spectromerty), H-NMR (Protone Nuclear Magnetic Resonance Spectroscopy) and XPS (X- Analysis by one or more methods selected from ray Photoelectron Spectroscopy, respectively.

When analyzing components in the separator, positive electrode, and negative electrode with one analysis method, the analysis conditions are maintained the same, and, in addition to the listed analysis methods, the analysis may be performed by an analysis method that can be used for elemental analysis of the surface, and the present invention is the method of analysis It is not limited by the sphere type.

In addition, in the case of analysis using one analytical method, repeated measurements may be performed 5 or more times, specifically, 10 or more times for each sample, and the average value may be taken.

In addition, if the difference between the concentration of the element component derived from the metal salt in the separator and the concentration of the element component derived from the metal salt in the electrode is greater than or equal to the known (pre-determined) error range in the corresponding analysis method and analysis device, it can be interpreted as a significant difference, and a significant difference When having, it may be determined that the concentration of the element component derived from the metal salt between the separator and the electrode is different from each other.

Specifically, the concentration in the separator, the positive electrode, and the negative electrode may be determined through the following method.

Each concentration and ratio of the metal salt can be determined through F-NMR and Cl-NMR analysis of a liquid sample diluted by melting the electrolyte contained in the separator, the positive electrode, and the negative electrode. In addition, if necessary, the proportion of solvent molecules and the content of additives can be determined through H-NMR analysis.

In addition, by directly preparing the electrolyte determined through the analysis, the analysis is performed again, and through this, the step of checking the analysis may be further included.

Experimentally, the difference in the concentration of lithium salt in the separator, the positive electrode, and the negative electrode may further include the step of directly confirming through the analysis of step (III).

The metal salt-derived element component, among the elements constituting the metal salt (electrolyte salt) dissolved in the electrolyte of the electrochemical device, may be an element(s) not present in the porous substrate of the electrode (specifically, the electrode active material layer) and the separator. . In other words, the element component derived from the metal salt may be an element that can exist only from the metal salt dissolved in the electrolyte in consideration of the specific materials of the separator, the positive electrode, and the negative electrode of the electrochemical device. At this time, when two or more different metal salts (electrolyte salts) are dissolved in the electrolyte, elemental components derived from metal salts are defined for each metal salt (electrolyte salt), and elemental analysis is performed for each metal salt (electrolyte salt) through an analysis method. Of course it could be. As a practical example, when the metal salt is a crystalline metal salt containing a sulfonyl group, the elemental component derived from the metal salt may be a sulfur component. When two or more different metal salts (electrolyte salts) are dissolved in the electrolyte, it is sufficient that the concentrations of the metal salt-derived element components between the separator surface and the electrode surface are different for one or more metal salts (electrolyte salts).

However, the present invention is not limited to the element component derived from the metal salt, and when the metal salt cannot be traced as the element component derived from the metal salt, for example, when all elements contained in the metal salt are also present in the electrode or the porous substrate, the element derived from the metal salt Of course, it can be substituted with the concentration or content of the binding state of the metal salt-derived element and/or the metal salt-derived functional group (functional group present in the metal salt) instead of the component, which may correspond to an example of a simple change based on the present invention. there is.

In terms of a manufacturing method, the electrochemical device according to the present invention includes an anode; cathode; a separator interposed between the anode and the cathode; electrolytes containing metal salts; and a case; including, wherein the metal salt (electrolyte salt) concentration of the electrolyte (injection electrolyte) injected into the case during manufacturing of the electrochemical device is the injection concentration, and the metal salt concentration of the electrolyte (used electrolyte) sealed inside the case is higher than the infusion concentration.

This is because the metal salt contained in the separator is dissolved into the injection electrolyte as the injected electrolyte comes into contact with the separator inside the case, and the injected electrolyte is converted into the used electrolyte. Experimentally, the configuration in which the injected electrolyte is converted to the used electrolyte may be indicated by the difference in the concentration of the element component derived from the metal salt on the surface of the electrode and the surface of the separator described above.

In the electrochemical device according to an embodiment, a metal ion participating in the electrochemical reaction of the electrochemical device is used as an active ion, and the metal ion of the metal salt contained in the separator may include an active ion, but is not necessarily limited thereto. it is not

In the electrochemical device according to one embodiment, the molar concentration of the salt of the active ion contained in the electrolyte, specifically, the molar concentration of the salt of the active ion contained in the used electrolyte is 0.5 to 6.0M, 0.5 to 5.0M, 0.5 to 4.0M , 0.5 to 3.0M, 0.5 to 2.5M, 0.5 to 1.2M, 0.7 to 6.0M, 0.8 to 6.0M, 0.9 to 6.0M, 1.0 to 6.0M, 1.1 to 6.0M, 1.2 to 6.0M, 1.3 to 6.0M , 1.4 to 6.0M, 1.5 to 6.0M, 1.6 to 6.0M, 1.7 to 6.0M, 1.8 to 6.0M, 1.9 to 6.0M, 2.0 to 6.0M, 2.1 to 6.0M, 2.2 to 6.0M, 2.3 to 6.0M , 2.4-6.0M, 2.5-6.0M, 0.7-5.0M, 0.8-5.5M, 0.9-5.0M, 1.0-5.0M, 1.1-5.0M, 1.2-5.0M, 1.3-5.0M, 1.4-5.5M , 1.5-5.0M, 1.6-5.0M, 1.7-5.0M, 1.8-5.0M, 1.9-5.0M, 2.0-5.0M, 2.1-5.0M, 2.2-5.0M, 2.3-5.0M, 2.4-5.0M , 2.5-5.0M, 0.7-4.0M, 0.8-4.0M, 0.9-4.0M, 1.0-4.0M, 1.1-4.0M, 1.2-4.0M, 1.3-4.0M, 1.4-4.0M, 1.5-4.0M , 0.7-1.2M, 0.9-1.2M, 0.8-2.5M, 1.0-2.5M, 1.2-2.5M, 1.3-2.5M, 1.4-2.5M, 1.5-2.5M, 1.6-2.5M, 1.7-2.5M , 1.8 to 2.5M, 1.9 to 2.5M, 1.5 to 2.2M, 1.7 to 2.2M, or 1.5 to 2.0M level, but is not limited thereto.

At this time, as described above, a concentration gradient in which the concentration of the metal salt increases in the separator or the electrode for supplying the metal salt to the electrolyte may be formed. As the active (metal) ions move from one electrode to the other through the separator, the concentration of the salt of the active ion in the electrolyte used is the maximum concentration in the concentration gradient, i.e., rather than being interpreted as the concentration of the salt of the average active ion in the electrolyte. , can be interpreted as the maximum concentration among the salt concentrations in the electrolyte contained (supported) in the positive electrode, the negative electrode, and the separator.

In terms of ionic conductivity of metal ions, the electrochemical device according to the present invention includes an anode; cathode; a separator interposed between the anode and the cathode; and an electrolyte, wherein the ionic conductivity of the separator in a state wetted to the electrolyte by using metal ions participating in the electrochemical reaction as active ions is 0.30 mS/cm or more, 0.32 mS/cm or more, 0.34 mS /cm or more, 0.36 mS/cm or more, 0.38 mS/cm or more, 0.40 mS/cm or more, 0.42 mS/cm or more, 0.44 mS/cm or more, 0.46 mS/cm or more, 0.48 mS/cm or more, 0.50 mS/cm or more, 0.52 mS/cm or more, 0.54 mS/cm or more, 0.56 mS/cm or more, 0.58 mS/cm or more, 0.60 mS/cm or more, 0.61 mS/cm or more, 0.62 mS/cm or more, 0.63 mS/cm or more, It may be 0.64 mS/cm or more, 0.65 mS/cm or more, 0.66 mS/cm or more, 0.67 mS/cm or more, 0.68 mS/cm or more, 0.69 mS/cm or more, or 0.70 mS/cm or more. Practically, the ionic conductivity may be 2.00 mS/cm or less, but is not limited thereto.

In addition, along with the ionic conductivity described above, the ion mobility coefficient of the active ions of the separator in a state wetted to the electrolyte is 0.30 or more, 0.32 or more, 0.34 or more, 0.36 or more, 0.38 or more, 0.40 or more, 0.42 or more, 0.44 or more. or more, 0.46 or more, 0.48 or more, 0.50 or more, 0.52 or more, 0.54 or more, 0.56 or more, 0.58 or more, 0.60 or more, 0.62 or more, 0.64 or more, 0.66 or more, or 0.68 or more. Practically, the ion migration coefficient may be 1.50 or less, but is not limited thereto.

As described above in the composite separation membrane, when the metal salt is a sulfonyl group-containing crystalline metal salt, particularly, at least one metal salt selected from compounds satisfying Formulas 1 to 4, the ionic conductivity of the metal ions of the separation membrane can be greatly improved.

It is noteworthy that the improved metal ion conductivity by the metal salt is realized even in a high-concentration electrolyte environment. Practically, the ionic conductivity of the separator in a state wetted with the electrolyte, and further, the ion mobility coefficient of the active ions may be the ion conductivity and the ion mobility coefficient in the electrolyte with a high concentration of the electrolyte. The high-concentration electrolyte may refer to a high-concentration liquid electrolyte in which the concentration of the salt of the active ion dissolved in the electrolyte (the total concentration of the salt of the active ion when the salts of the active ions are two or more different from each other) is 1M or more. Specifically, the concentration of the active ion salt in the high-concentration electrolyte is 1.0M or more, 1.1M or more, 1.2M or more, 1.3M or more, 1.4M or more, 1.5M or more, 1.6M or more, 1.7M or more, 1.8M or more, 1.9 M or more, 2.0M or more, 2.1M or more, 2,2M or more, 2.3M or more, 2.4M or more, or 2.5M or more, and may be substantially less than or equal to 6M concentration. The salt of the active ion dissolved in the electrolyte is sufficient as long as it is a material commonly used as a salt of the electrolyte in the field of electrochemical devices. In this case, the salt of the active ion dissolved in the electrolyte may include the metal salt described above in the composite separator, but may be different from the metal salt described above in the composite separator. When a salt concentration gradient exists in the electrolyte inside the electrochemical device, the concentration of the salt of the active ion in the high-concentration electrolyte may be based on the maximum concentration value in the concentration gradient, and substantially, the concentration of the salt of the active ion in the positive electrode, the negative electrode, and the separator It may be based on the highest concentration value by measuring the concentration.

In each of the above-described electrochemical devices, the separator may be the same as or similar to the above-described composite separator. Accordingly, the electrochemical device includes all the contents described above in the composite separator. The composite separator supplies the metal salt to the electrolyte in contact with the electrolyte, and the above-described flame retardancy or the above-described ion conductive properties may be exhibited by the metal salt remaining on the porous substrate. On the other hand, since the composite separator includes the metal salt fixed to the porous substrate, the above-described flame retardancy or the above-described ion conductive properties may be exhibited.

In each of the above-described electrochemical devices, the positive electrode, the negative electrode, the electrolyte, the case, etc. may be a positive electrode, a negative electrode, an electrolyte, a case, etc. commonly used in the electrochemical device in consideration of the specific type of the electrochemical device. However, when the separator acts as a salt source to the electrolyte, of course, the electrolyte may be a highly concentrated electrolyte than the injected electrolyte.

Taking a lithium secondary battery as a representative example of an electrochemical device as an example, the positive electrode may include a positive electrode current collector and a positive electrode active material layer positioned on at least one surface of the positive electrode current collector, and the negative electrode includes at least one of the negative electrode current collector and the negative electrode current collector It may include a negative electrode active material layer positioned on the surface, the electrolyte may be a liquid electrolyte in which a lithium salt is dissolved in a solvent, and the case may be a pouch-type case or a cylindrical or prismatic case.

In detail, the positive electrode active material contained in the positive electrode active material layer can be used as long as it is a material capable of reversible desorption/insertion of lithium ions, and any electrode material used for the positive electrode of a typical lithium secondary battery may be used. For example, the cathode active material may include LiMO ₂ (M is one or two or more transition metals selected from Co and Ni); LiMO ₂ substituted with one or more heterogeneous elements selected from Mg, Al, Fe, Ni, Cr, Zr, Ce, Ti, B and Mn, or coated with an oxide of these heterogeneous elements (M is one from Co and Ni or two or more selected transition metals); Li _x Ni _α Co _β M _γ O ₂ (real with 0.8≤x≤1.5, real with 0.7≤α≤0.9, real with 0.05≤β≤0.35, real with 0.01≤γ≤0.1, α + β + γ =1 , M is one or more elements selected from the group consisting of Mg, Sr, Ti, Zr, V, Nb, Ta, Mo, W, B, Al, Fe, Cr, Mn and Ce); or Li _x Ni _a Mn _b Co _c M _d O ₂ (real number 0.9≤x≤1.1, real number 0.3≤a≤0.6, real number 0.3≤b≤0.4, real number 0.1≤c≤0.4, 0≤d≤ Real number 0.4, a+b+c+d=1, M is selected from the group consisting of Mg, Sr, Ti, Zr, V, Nb, Ta, Mo, W, B, Al, Fe, Cr and Ce an oxide having a layered structure typified by ) and the like; Li _a Mn _2-x M _x O ₄ (M=Al, Co, Ni, Cr, Fe, Zn, one or more elements selected from Mg, B and Ti, real number 1≤a≤1.1, 0≤x a real number of ≤0.2) or an oxide having a spinel structure typified by Li ₄ Mn ₅ O ₁₂ and the like; Or LiMPO ₄ (M is Fe, Co, Mn) may be a phosphate-based material having an olivine structure, such as, or a mixture thereof, but is not limited thereto.

In detail, the anode active material of the anode active material layer may be a material commonly used for the anode of a lithium secondary battery, and the anode active material may be a material capable of lithium intercalation. For example, the negative electrode active material is lithium (metal lithium), graphitizable carbon, non-graphitizable carbon, graphite, silicon, Sn alloy, Si alloy, Sn oxide, Si oxide, Ti oxide, Ni oxide, Fe oxide (FeO), Lithium-titanium oxide (LiTiO ₂ , Li ₄ Ti ₅ O ₁₂ ), a mixture thereof, or a composite thereof may be one or more selected from the group consisting of, but not limited to.

Each of the positive electrode active material layer and the negative electrode active material layer may further contain an organic binder, and the binder can be used as long as it is a material commonly used for electrodes of lithium secondary batteries, does not chemically react with the electrolyte, and does not react with the active material and the active material. A polymer capable of binding the current collectors is sufficient. As a specific example, the positive electrode active material layer and the negative electrode active material layer binder are each independently of each other, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride-trichloroethylene copolymer, polyvinylidene fluoride Methyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyethylene-vinyl acetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyano Noethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxyl methyl cellulose, styrene-butadiene copolymer, acrylonitrile-styrene-butadiene copolymer, polyimide, polytetrafluoroethylene or these Of course, the present invention cannot be limited by the material of the binder.

The positive electrode current collector or the negative electrode current collector, independently of each other, suffices as long as the positive electrode current collector or the negative electrode current collector used in a typical lithium secondary battery. In detail, the positive electrode current collector or the negative electrode current collector may have excellent conductivity and may be any material that is chemically stable during charging and discharging of the battery. Specifically, the positive electrode current collector or the negative electrode current collector may be a conductive material such as graphite, graphene, titanium, copper, platinum, aluminum, nickel, silver, gold, aluminum or carbon nanotube, but the present invention is not limited thereto not.

If necessary, the positive electrode active material layer or the negative electrode active material layer may further contain a conductive material, and the conductive material may be any conductive material commonly used in lithium secondary batteries to improve electrical conductivity of the active material layer. Specific examples of the conductive material include conductive carbon bodies such as carbon black, acetylene black, Ketjen black, channel black, farness black, lamp black, thermal black, or a mixture thereof; conductive fibers such as carbon fibers and metal fibers; Conductive nanostructures such as carbon nanotubes or graphene; and the like, but are not limited thereto.

The electrolyte may be a liquid electrolyte, and in a typical lithium secondary battery, a non-aqueous electrolyte that smoothly conducts ions involved in charging and discharging of the battery is sufficient. For example, the non-aqueous electrolyte may include a non-aqueous solvent and a lithium salt. The non-aqueous organic solvent may be a carbonate, ester, ether or ketone alone or a mixed solvent thereof. In particular, when a carbonate-based solvent or an ether-based solvent is used alone or as a mixed solvent, it may be more advantageous to form a coordination structure by interaction with an active metal ion and a sulfonyl group. Specifically, the non-aqueous organic solvent is ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, vinylene carbonate , vinyl ethylene carbonate, fluoroethylene carbonate, dimethyl carbonate, diethyl carbonate, di(2,2,2-trifluoroethyl) carbonate, dipropyl carbonate, dibutyl carbonate, ethylmethyl carbonate, 2,2,2-tri Fluoroethyl methyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, 2,2,2-trifluoroethyl propyl carbonate, methyl isopropyl carbonate, methyl formate, ethyl formate, propyl formate, butyl formate, dimethyl ether , diethyl ether, dipropyl ether, methylethyl ether, methylpropyl ether, ethylpropyl ether, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate Cypionate, methyl butyrate, ethyl butyrate, propyl butyrate, butyl butyrate, γ-butyrolactone, 2-methyl-γ-butyrolactone, 3-methyl-γ-butyrolactone, 4-methyl-γ-butyrolactone , γ-thiobutyrolactone, γ-ethyl-γ-butyrolactone, β-methyl-γ-butyrolactone, γ-valerolactone, σ-valerolactone, γ-caprolactone, ε-caprolactone, β-propiolactone, tetrahydrofuran, 2-methyl tetrahydrofuran, 3-methyltetrahydrofuran, trimethyl phosphate, triethyl phosphate, tris(2-chloroethyl) phosphate, tris(2,2,2-trifluoro roethyl) phosphate, tripropyl phosphate, triisopropyl phosphate, tributyl phosphate, trihexyl phosphate, triphenyl phosphate, tritolyl phosphate, methyl ethylene phosphate, ethyl ethylene phosphate, dimethyl sulfone, ethyl methyl sulfone, methyl trifluoromethyl sulfone, ethyl trifluoromethyl sulfone, methyl pentafluoroethyl sulfone, ethyl pentafluoroethyl sulfone, di(trifluoromethyl)sulfone, di(pentafluoroethyl) sulfone , trifluoromethyl pentafluoroethyl sulfone, trifluoromethyl nonafluorobutyl sulfone, pentafluoroethyl nonafluorobutyl sulfone, sulfolane, 3-methylsulfolane, 2-methylsulfolane, 3-ethylsulfone porane, 2-ethylsulfolane, or a mixed solvent thereof, but is not limited thereto. For example, the solvent of the electrolyte may be an ionic liquid.

The lithium salt may include, but is not limited to, a case where the metal ion of the metal salt described above in the composite separator is a lithium ion, and a lithium salt commonly used to smoothly conduct ions involved in charging and discharging of a battery. it is enough

Optionally, the electrolyte forms a SEI (Solid Electrolyte Interface) film such as a halogen-substituted or unsubstituted cyclic carbonate-based compound, a nitrile-based compound, a phosphate-based compound, a borate-based compound, a sulfate-based compound, a sultone-based compound, or a lithium salt-based compound Of course, it may further include known additives, such as additives for

The electrochemical device may be a primary battery or a secondary battery capable of an electrochemical reaction. More specifically, lithium primary battery, lithium secondary battery, lithium-sulfur battery, lithium-air battery, sodium battery, aluminum battery, magnesium battery, calcium battery, zinc battery, zinc-air battery, sodium-air battery, aluminum-air battery It may be a battery, a magnesium-air battery, a calcium-air battery, a super capacitor, a dye-sensitized solar cell, a fuel cell, a lead storage battery, a nickel cadmium battery, a nickel hydrogen storage battery, or an alkaline battery, but is not limited thereto.

The present invention includes an electrochemical module in which the above-described electrochemical device is a unit cell, two or more cells are arranged and electrically connected to each other. Of course, the electrochemical module may have an arrangement and structure of cells commonly used in the field of electrochemical devices, and may further include a conventional cooling member such as a cooling plate.

The present invention includes a device powered by the aforementioned electrochemical device or the aforementioned electrochemical module. For example, the device may be a device that requires medium or large power, such as an electric vehicle or a hybrid vehicle, but is not limited thereto.

The present invention includes a coating solution coated on a constituent member of an electrochemical device in contact with an electrolyte. The coating solution of the present invention is a coating solution for coating a component of an electrochemical device in direct contact with the electrolyte, except for the electrolyte, and contains a metal salt.

The metal salt contained in the coating solution is coated on the constituent members of the electrochemical device, so that the metal salt can be supplied to the electrolyte during assembly (manufacturing) into the electrochemical device, but the action of the metal salt in the coating solution is necessarily limited to the metal salt source to the electrolyte can't be

The metal salt in the coating solution according to the present invention may be the same as or similar to the metal salt described above in the composite separator, and thus the coating solution includes all of the above-mentioned details related to the metal salt in the composite separator.

As an advantageous example, the coating solution may include a sulfonyl group-containing metal salt. By coating a component of an electrochemical device with a coating solution containing a sulfonyl group-containing metal salt, the coated component acts as a salt source to the electrolyte, or, together with or independently of, imparts flame-retardant properties to the component can do.

As a more advantageous example, the coating solution may include any one or more or two or more metal salts selected from the compounds satisfying the above-described Chemical Formulas 1 to 4. By containing such a metal salt, it is possible to improve the electrolyte wettability together with or independently of the flame retardant properties or the action of the salt source, or, together or independently, improve the ionic conductivity of the active ions.

The solvent of the coating solution is a C1-C3 lower alcohol solvent, ketone-based solvent in which metal salts and binding components (for example, linear polymers and/or crosslinked polymers) used when necessary are easily dissolved and completely volatilized by simple drying. It is preferable that one or more solvents are selected from solvents and carbonate-based solvents. Examples of the C1-C3 lower alcohol solvent include methanol, ethanol, and isopropyl alcohol. Examples of the ketone solvent include acetone, methyl ethyl ketone, and methyl isobutyl ketone. Examples of the carbonate solvent include ethylene carbonate. , propylene carbonate, fluoroethylene carbonate, dimethyl carbonate, diethyl carbonate, and the like. At this time, when the coating solution does not contain a binding component, the coating solution may contain only the solvent described above as a liquid raw material (based on room temperature). On the other hand, when the coating solution contains a binder component, the coating solution contains only the above-described solvent as a liquid raw material (based on room temperature), or one or two or more selected from the group of monomers, oligomers and prepolymers having curing ability with the solvent are selected for curing. It may contain only a liquid curing component that is converted into a binder component by

It is sufficient that the constituent member is a member in direct contact with an electrolyte, specifically, a liquid electrolyte in a state of being assembled into an electrochemical device. For example, the constituent member may be at least one selected from a positive electrode, a negative electrode, a separator, and a case. Of course, when there are two or more constituent members selected, each of them may be coated with a coating solution.

Specifically, the constituent member includes a positive electrode surface including a surface with pores (a cathode active material layer surface including a surface with pores), a negative electrode surface including a surface with pores (a surface of a negative electrode active material layer including a surface with pores) ), the surface of the separation membrane including the surface with pores (or the surface area described above in the composite separation membrane above), the inner surface of the case, etc., but is not limited thereto.

As described above, the coating solution may further contain one or two or more curing components selected from the group of monomers, oligomers and prepolymers having curing ability, a linear polymer, or a mixture thereof together with the above-mentioned metal salt, and the curing component When included, it may further contain an additive including an initiator.

The curing component, initiator, and linear polymer of the coating solution are the same or similar to the above-mentioned binding component, the curing component converted into a crosslinked polymer, initiator, etc. in the composite separator, and the coating solution is related to the binding component and the curing component in the composite separator and includes all of the above. In this case, the weight ratio of the metal salt: the binding component may correspond to the weight ratio of the metal salt: the curing component in the coating solution.

The concentration of the metal salt in the coating solution may be 0.1 to 5 M level, but is not necessarily limited thereto.

By applying and drying the coating solution containing the metal salt and the curing component to the component member, a coating layer containing the crystalline metal salt in a fixed state to the component member can be formed.

The coating solution may further include inorganic particles, organic particles, organic-inorganic composite particles, or mixed particles thereof. Specifically, the coating solution may include a metal salt, inorganic particles, organic particles, organic-inorganic composite particles, or a particulate form of mixed particles thereof. In this case, the coating solution may further include the above-described curing component or an organic binder or a curing component and an organic binder.

The particulate phase contained in the coating solution is the same or similar to the particulate phase described above in the porous coating layer of the composite separator, and the organic binder contained in the coating solution is the same or similar to the binder described in the porous coating layer of the composite separator. Accordingly, the coating solution includes all of the above-mentioned content related to the inorganic particles, organic particles, organic-inorganic composite particles or mixed particles thereof in the composite separator, and the binder.

When the coating solution further contains a particulate phase, the coating solution may contain 10 to 1000 parts by weight, specifically 50 to 1000 parts by weight, and more specifically 100 to 500 parts by weight of the metal salt based on 100 parts by weight of the particulate phase. The content of the metal salt compared to the particulate is uniformly distributed on the particulate surface of the porous coating layer produced using the coating solution, furthermore, the particulate surface and the binding component and/or the binder, ensuring flame retardancy and/or ionic conductivity It is a content range advantageous for improving.

The coating solution may contain 1 to 30 parts by weight, specifically 5 to 10 parts by weight of a binder, a curing component, or a binder and a curing component based on 100 parts by weight of the particulate form, but is not limited thereto. However, in the above range, the porosity is maintained due to the void space between the particles, and it is advantageous for the particles to be stably fixed to the porous film by the binder and/or the curing component. At this time, the coating solution may contain a particle phase at a level of 5 to 30% by weight, but is not limited thereto, and it is sufficient as long as it is a weight% that can indicate appropriate application suitability in consideration of the spherical application method of the coating solution.

By forming the coating layer on the porous film using the coating solution containing the metal salt and the particulate phase, the porous coating layer containing the metal salt can be formed on the porous film. In this case, the coating solution may be a coating solution for preparing a separator. Here, the porous film is the same as or similar to the porous film described above in the composite separator, and thus, the coating solution includes all of the above-described contents related to the porous film in the composite separator.

The present invention includes a method for manufacturing an electrode (anode or cathode) using the above-described coating solution. In this case, the coating solution may be a solution for coating an electrode (anode or cathode) of an electrochemical device.

Specifically, the method of manufacturing an electrode according to the present invention includes the step of applying the above-described coating solution to the electrode active material layer of the electrode. In this case, the electrode active material layer may be a positive electrode active material layer or a negative electrode active material layer. It goes without saying that the electrode active material layer may be manufactured by a conventionally known conventional manufacturing method, such as applying, drying, and rolling a slurry further comprising a particulate electrode active material, a binder, and, if necessary, a conductive material to the current collector.

In the case of prioritizing the application of the coating solution, if the action as a metal salt source is prioritized, it is okay as long as the coating is made so that the metal salt having a content that can increase the concentration of the liquid electrolyte from the injection concentration to the design concentration is located on the electrode active material layer. . As a practical example, the coating may be performed so that the metal salt content, which is the mass of the metal salt per unit area of the electrode active material layer, is at a level of 0.1 to 5.0 mg/cm ² .

Together with or independently of this, when priority is given to improving flame retardancy or ionic conductivity, the metal salt dissolved into the electrolyte and remaining in the electrode active material layer or the metal salt remaining fixed in the electrode active material layer, per unit area of the electrode active material layer Based on the metal salt content, which is the mass of the metal salt, 0.3 to 5.0 mg/cm ² , 0.3 to 4.0 mg/cm ² , 0.3 to 3.0 mg/cm ² , 0.3 to 2.5 mg/cm ² , 0.3 to 2.0 mg/cm ² , Application may be carried out to a level of 0.4 to 1.5 mg/cm ² , 0.5 to 1.4 mg/cm ² , or 0.5 to 1.2 mg/cm ² .

Application of the coating solution is spin coating, roll coating, spray coating, dip coating, flow coating, doctor blade, dispensing, inkjet printing, offset printing , stencil printing, screen printing, pad printing, gravure printing, reverse gravure printing, gravure offset printing, flexography printing, stencil printing, imprinting, xerography, slot die coating, It may be performed by one or more methods selected from bar coating and roll-to-roll coating, but is not limited thereto.

After application of the coating solution is performed, the step of applying energy to the application of the coating solution may be further performed. The applied energy may be thermal energy, light energy, or heat and light energy, and the application of heat and light energy may include sequential application or simultaneous application.

This application of energy is an application for more rapid volatilization removal (drying) of the solvent in the coating material, and/or application for converting the curing component contained in the coating material into a binder component when the coating solution contains a curing component. can When applying energy for drying and applying energy for conversion to a binding component, of course, the types of applied heat, light, or heat and light energy may be different from each other. Of course, the application of energy for conversion may be sequentially performed.

When applying energy for drying, light known as heat rays such as heat and/or near-infrared light may be applied enough to promote volatilization of the solvent contained in the coating material within a range in which the constituent members are not damaged.

When applying energy for curing the curing component, heat, light, or heat and light may be applied so that the curing component is cured or curing is accelerated in consideration of the spherical curing ability of the curing component contained in the coating material. For example, if the curing component is thermally curable, thermal energy capable of promoting or causing curing may be applied. As another example, when the curing component is light-curable, light including a wavelength band required for curing the applied curing component may be applied. As a practical example, when the curing component has UV curing ability, light including UV may be applied.

However, the application of energy for drying may be selectively performed if necessary. For example, drying may be performed by volatilization drying at room temperature, hot or cold air drying, heat drying (thermal energy or infrared energy, etc.), and the drying may be appropriately designed according to the electrode manufacturing process design.

As a modification of the above-described method of manufacturing the electrode, the electrode active material and the metal salt-containing solution are mixed and dried to prepare an electrode active material coated with a metal salt, and then the electrode active material coated with a metal salt, a binder, and, if necessary, a conductive material, etc. By applying, drying and rolling the electrode slurry to the current collector, it is possible to manufacture a metal salt-containing electrode.

As another modification of the above-described method for manufacturing an electrode, an electrode slurry containing an electrode active material, a metal salt, a binder, and, if necessary, a conductive material is coated on a current collector, dried and rolled to manufacture an electrode containing a metal salt. . These modified examples for introducing a metal salt into the electrode active material layer are also examples that those skilled in the art can easily derive based on the technical idea provided by the present invention, and are included in the scope of the present invention.

The present invention includes an electrochemical device including an electrode manufactured by the above-described manufacturing method.

The present invention includes a method for manufacturing a composite separator using the above-described coating solution.

The method for manufacturing a composite separator according to the present invention includes applying the above-described coating solution to a porous substrate. In this case, the porous substrate may include a porous film, or a porous film and a porous coating layer positioned on one or both surfaces of the porous film. The porous substrate may be the same as or similar to the above-described porous substrate in the composite separator, and thus, the method for manufacturing the composite separator may include all of the above-described contents related to the porous substrate in the composite separator.

After the application of the coating solution is performed, the step of applying energy to the application of the coating solution may be further performed, which is to accelerate or cause drying and/or curing of the curing component if the coating solution contains a curing component. it may be for

The coating solution application method, sphere application amount, energy application, etc. are similar to or the same as those described above in the electrode manufacturing method, and thus, the manufacturing method of the composite separator may include all of the contents described above in the electrode manufacturing method.

When the coating solution does not contain a binding component, a coating layer of a metal salt soluble in an electrolyte may be formed on the porous substrate.

When the coating solution contains a binding component, a coating layer of the metal salt fixed to the porous substrate may be formed.

When the coating solution contains a binder component and a particulate phase, a porous coating layer containing a metal salt may be formed on the porous substrate and having porosity due to void spaces between particles of the particle phase.

The present invention includes an electrochemical device including a composite separator manufactured by the method for manufacturing the composite separator described above.

The present invention includes a method for manufacturing a separator using the above-described coating solution.

According to one embodiment of the above-described coating solution on a porous film, the method for manufacturing a separator according to the present invention comprises: a metal salt; particulate; and applying a coating solution containing a binder, a curing component, or a binder and a curing component.

Thereby, on each of the surfaces of at least one side (the side facing the electrode) or both sides (the side facing the electrode) of the porous film, it has porosity due to the void space between particles in the form of particles, contains a metal salt, and the porous film A separator having a metal salt-containing porous coating layer bound thereto may be prepared.

After the application of the coating solution is performed, the step of applying energy to the application of the coating solution may be further performed, which is to accelerate or cause drying and/or curing of the curing component if the coating solution contains a curing component. it may be for

The porous film may be the same as or similar to the above-described porous film in the composite separator, and thus, the method of manufacturing the separator may include all of the above-described contents related to the porous film in the composite separator.

The coating solution application method, sphere application amount, energy application, etc. are similar to or the same as those described above in the electrode manufacturing method, and thus, the separator manufacturing method may include all of the contents described above in the electrode manufacturing method.

The present invention includes a method for manufacturing a case for an electrochemical device using the above-described coating solution.

The manufacturing method of the case according to the present invention includes the step of applying the above-described coating solution to the inner surface of the case, and if necessary, may further include the step of applying energy to the coating material of the coating solution. In this case, of course, the inner surface of the case to which the coating solution is applied may be a region in contact with the liquid electrolyte when assembling into an electrochemical device.

Depending on the specific composition of the coating solution, a metal salt located on the inner surface of the case may be supplied as an electrolyte, and together or independently from this, the flame retardancy of the case is ensured by the metal salt remaining or fixed on the inner surface of the case, or activity in the electrolyte A smoother flow of ions can be induced.

The case may be the same as or similar to the case described above in the electrochemical device, and thus, the method of manufacturing the case may include all of the above-described contents related to the case in the electrochemical device.

The coating solution application method, sphere application amount, energy application, etc. are similar to or the same as those described above in the electrode manufacturing method, and thus, the case manufacturing method may include all of the contents described above in the electrode manufacturing method.

The present invention includes a method for manufacturing an electrochemical device comprising; applying the above-described coating solution to a component of the electrochemical device in contact with the electrolyte, and, if necessary, a component to which the coating solution is applied (coating solution) It may further include the step of applying energy to the coating material). At this time, a component obtained by applying a coating solution and applying energy when necessary is collectively referred to as a component containing a metal salt.

When the constituent member is an electrode, the method of manufacturing the electrochemical device may include the above-described method of manufacturing the electrode. In addition, when the constituent member is a separator, the method for manufacturing the electrochemical device may include the above-described method for manufacturing the composite separator or the method for manufacturing the separator. When the constituent member is a case, the manufacturing method of the electrochemical device may include the above-described case 2 manufacturing method. When two or more components are selected from an electrode, a separator, and a case, the method for manufacturing an electrochemical device may include all of the above-described methods for manufacturing each of the two or more components (metal salt-containing component).

The method of manufacturing an electrochemical device according to an embodiment may further include; putting an electrode assembly in which a separator is positioned between an anode and a cathode and an electrolyte into a case having an internal accommodating space and sealing the case; , an anode, a cathode, a separator, and at least one component selected from the case may be a component containing a metal salt.

In the case where the constituent member is a separator as an example, the method for manufacturing an electrochemical device according to an embodiment a) applies a coating solution to a separator (corresponding to a porous substrate) to form a metal salt-containing separator (corresponding to a composite separator) manufacturing; b) manufacturing an electrode assembly in which a metal salt-containing separator is positioned between the positive electrode and the negative electrode; and c) putting the electrode assembly and electrolyte into a case having an internal accommodation space and sealing the case, and further, d) inside the sealed case, the metal salt contained in the metal salt-containing separator is dissolved in the electrolyte The step of being; may further include.

As the metal salt contained in the metal salt-containing separator can be dissolved into the electrolyte upon contact with the liquid electrolyte, the concentration of the metal salt (corresponding to the salt of the active ion or the electrolyte salt) of the liquid electrolyte injected (injected) into the case in step c) may be lower than the metal salt concentration in the electrolyte when an electrochemical device is used. In this case, it goes without saying that the metal salt contained in the metal salt-containing separation membrane may be a salt of an active ion. In addition, in step a), the coating may be made so that a metal salt having a content or more that can increase the concentration of the liquid electrolyte from the injection concentration to the design concentration is located. As a practical example, the application may be performed such that the metal salt content, which is the mass of the metal salt per unit area of the separator (corresponding to the porous substrate), is at a level of 0.1 to 5.0 mg/cm ² .

When it is desired to impart flame retardancy or improved ionic conductivity properties to the separation membrane, the metal salt may be a metal salt containing a sulfonyl group, advantageously one or more metal salts selected from compounds satisfying Chemical Formulas 1 to 4. When it is desired to impart flame retardancy or improved ionic conductivity properties to the separator, in step a), the metal salt dissolved into the electrolyte and remaining in the separator (corresponding to the porous substrate) or the state of being fixed to the separator (corresponding to the porous substrate) The retained metal salt is based on the metal salt content, which is the mass of the metal salt per unit area of the separation membrane (corresponding to the porous substrate), 0.3 to 5.0 mg/cm ² , 0.3 to 4.0 mg/cm ² , 0.3 to 3.0 mg/cm ² , 0.3 to 2.5 mg/cm ² , 0.3 to 2.0 mg/cm ² , Application may be carried out to a level of 0.4 to 1.5 mg/cm ² , 0.5 to 1.4 mg/cm ² , or 0.5 to 1.2 mg/cm ² . In this case, the coating solution may contain a binding component, and of course, the metal salt may be coated while being fixed to the separation membrane (corresponding to the porous substrate) by the binding component.

The present invention includes an electrochemical device manufactured by the above-described manufacturing method.

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples. However, the following examples and comparative examples are merely examples for explaining the present invention in more detail, and the present invention is not limited by the following examples and comparative examples.

1) Ion conductivity

The ionic conductivity of the separation membrane can be confirmed through the following method.

(IC _separator )

In this case, the IC _separator is the ionic conductivity of the separation membrane in the state in which the liquid electrolyte is wetted.

The ionic conductivity is determined by removing the liquid electrolyte-wetted separator from the battery prepared in the Example or Comparative Example and then cutting it into a circle with a diameter of 18 mm and manufacturing the coin cell 2032, or cutting it into a circle with a diameter of 18 mm. The same liquid electrolyte as in each Example or Comparative Example is injected into the separated membrane and wetted, and then the coin cell 2032 is manufactured, and it can be measured using an AC impedance measurement method depending on the temperature. The ionic conductivity was measured in a frequency band of 1 MHz to 0.01 Hz using a VMP3 measuring device.

Hereinafter, the Nyquist plot in which the ionic conductivity (IC) of the separator in which the liquid electrolyte is wetted will be described in detail. The separation membrane in the wet state of the liquid electrolyte is an ion conductor, and represents an open shape that rises vertically on the Nyquist plot, and the impedance resistance value of the horizontal axis means resistance to ion conduction. As the resistance value for ion conduction obtained above, it can be calculated using the following formula.

[Formula 1]

IC = L/(R _ion × A)

In this case, L is the thickness of the specimen (thickness of the separator), A is the area of the specimen, R _ion = R ₂ -R ₁ , R ₁ is the resistance of the high-frequency region in the Nyquist plot, and R ₂ is the Nike It is the resistance of the low frequency region in the strode plot.

The ionic conductivity of the separation membrane can be confirmed through the method described above.

2) Li transport number

To measure the lithium ion migration coefficient, take out the liquid electrolyte-wetted separator from the secondary battery prepared in Examples or Comparative Examples, cut it into a circle with a diameter of 18 mm, and sandwich the separator between two lithium foils with a diameter of 16 mm. to manufacture a coin cell 2032, or put a separator cut into a circle with a diameter of 18 mm between two lithium foils with a diameter of 16 mm and inject the same liquid electrolyte as in each Example or Comparative Example to wetting the coin cell (2032) is prepared. Measure the primary impedance resistance value of the prepared coin cell, apply a voltage of 10 mV to observe the current change for 3600 sec, and measure the secondary impedance resistance value.

Thereafter, the lithium ion migration coefficient (t _Li ⁺ ) may be calculated by substituting the measured values according to the following Bruce and Vincent method.

[Formula 2]

t _Li ⁺ = (I ^s (ΔV-I ⁰ R ⁰ ))/(I ⁰ (ΔV-I ^s R ^s ))

In this case, I ^s is a steady-state current, ΔV is an applied voltage, I ⁰ is an initial current, R ⁰ is an initial resistance, R ^s is a steady state It stands for steady-state resistance.

3) Analysis of Molar Concentration and Concentration Gradient of Electrolyte in Battery Material

Experimentally, the concentration of the metal salt in the electrode and the separator may be measured by the following analysis method, according to the following method (1) and/or method (2).

Method (1): 1) Close the sealing of the electrochemical device (secondary battery manufactured in the embodiment) to open at least one end, and between the tab provided for electrical connection to the outside and the electrode complex of the positive electrode-separator-negative electrode Separation and recovery of the electrode complex by cutting the connection; recovering the electrode composite molded in the epoxy resin by curing the recovered electrode composite at 60°C for 24 hours or more using an epoxy resin for molding; The concentration gradient of the active metal ions in the cross-section of the electrode composite was directly confirmed by analyzing the molded electrode composite into a cross-section specimen with a thickness of less than 20 μm using an ion beam and analyzed by Neutron Depth Profiling.

Method (2): 1) Close the sealing of the electrochemical device (secondary battery manufactured in the embodiment) to open at least one end, and between the tab provided for electrical connection with the outside and the electrode complex of positive electrode-separator-cathode Separation and recovery of the electrode complex by cutting the connection; 2) In the recovered electrode complex, a solution in which the separator, the positive electrode, and the negative electrode were each immersed in anhydrous deuterated dimethyl sulfoxide for 24 hours was analyzed by the following method.

Analysis methods: F-NMR (Florine Nuclear Magnetic Resonance Spectroscopy), Cl-NMR (Chlorine Nuclear Magnetic Resonance Spectroscopy), ICP-MS (Inductively Coupled Plasma Mass Spectromerty), H-NMR (Protone Nuclear Magnetic Resonance Spectroscopy) and XPS (X- Analysis by one or more methods selected from ray Photoelectron Spectroscopy, respectively.

4) Battery performance evaluation

In the secondary battery prepared in Example, the initial charge/discharge capacity was observed with a current of 0.1 C (= 0.3 mA/cm 2 ) in a voltage range of 3.0 to 4.2 V, and the output characteristics (discharge characteristics by rate) were obtained by placing the lithium battery at room temperature ( 25°C) at a current of 0.2 C, and discharged at 0.2C/0.5C/1.0C/1.5C/2.0C, respectively.

Output capacity retention rate (%) = [discharge capacity at a specific rate / initial 0.1C discharge capacity] × 100

The lifespan characteristics of lithium batteries according to the number of charging/discharging were observed at room temperature (25°C) and high temperature (45°C) under a current of 1.0 C, respectively.

Cycle capacity retention rate (%) = [200th cycle discharge capacity/first cycle discharge capacity] × 100

5) Qigongdo

The porosity (volume %) of the specimen was measured using a mercury intrusion porosimetry (Mercury intrusion porosimetry, equipment name: AutoPore IV 9500, equipment manufacturer: Micromeritics Instrument Corp.). In order to exclude the influence of pores formed by the stacking of the samples, the porosity of the samples was calculated under a pressure range of 30 psia to 60000 psia.

6) Liquid electrolyte wettability evaluation

20 μl of a liquid electrolyte in which 1 mol of LiPF6 was dissolved in a solvent in which ethylene carbonate and dimethyl carbonate were mixed as a reference electrolyte in a 1:1 volume ratio was dropped on the separators prepared in Examples and Comparative Examples, and the wettability behavior was observed after 60 seconds. .

7) Flame retardant evaluation

After being impregnated in the following reference electrolyte for 1 minute and then recovered, the following flame retardancy is performed at the point in time when the droplet does not fall from the separator to the floor for 1 minute when the gravity direction and the in-plane direction of the separator are positioned in parallel immediately after recovery test.

Reference electrolyte: mixed solvent of ethylene carbonate and dimethyl carbonate in a volume ratio of 1:1, lithium salt of LiPF ₆ , LiPF ₆ concentration of 1M, temperature of 25℃ ± 5℃

Flame-retardant test: the length of the flame in the air = 5 to 10 cm, the flame tip temperature = 1000 to 1500 ° C, the length of the flame region that is not in contact with the separator when the flame is applied to the separator = 50 to 80% of the length of the flame in the air, the flame moving speed in contact with the separator = 1 to 5 cm/sec

The evaluation results according to the flame retardancy evaluation method for the separation membranes prepared in Examples and Comparative Examples are shown in FIGS. 1 to 8 . As shown in Figures 1 to 7, all the separators manufactured and evaluated through Examples did not generate a flame during the flame retardancy test, but as shown in FIG. It was confirmed that this occurred.

8) Scanning electron microscope and energy dispersion component analysis

From the surface and cross-section of the composite separator and the surface and cross-section of the anode and cathode facing the composite separator, scanning electron microscopy and energy dispersive component analysis (Field Emission Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (FE-SEM, EDS) ), equipment name: S-4800, equipment manufacturer: Hitachi). Through the morphology and component analysis of the surface and cross section, the detection and content difference of elemental components derived from metal salts in the sample were confirmed.

9) X-ray diffraction analysis

The composite separator prepared in Examples was cut to an appropriate size, and high-resolution X-ray diffraction analysis (High Resolution X-ray Diffractometer (HRXRD), equipment name: SmartLab, equipment manufacturer: RIGAKU, Cu Kα ray) was performed. Through X-ray diffraction analysis of the metal salt-coated composite separator, it was confirmed whether the metal salt coated on the separator had a crystalline phase and whether it was dissociated.

The crystal state evaluation results of the metal salts for the separation membranes prepared in Examples and Comparative Examples are shown in FIG. 9 . In the separator prepared and evaluated in Example 7, a diffraction peak (2 theta = 33.3˚) corresponding to the lithium bis(trifluoromethanesulfonyl)imide metal salt in an undissociated crystalline state was observed, but Comparative Example 3 It was confirmed that a diffraction peak indicating a crystalline phase was not observed in the separation membrane coated with the composite electrolyte prepared through the dissociated metal salt.

10) Adhesion analysis

After attaching the membrane samples prepared in Examples and Comparative Examples to the slide glass, adhesion evaluation was performed using a universal testing machine (Universal Testing Machine, equipment name: DA-01, equipment manufacturer: Petrol LAB).

The results of evaluation of adhesion to the separators prepared in Examples and Comparative Examples are shown in FIG. 10 . Although the separation membrane prepared and evaluated in Example 7 was completely dried and no adhesive strength was measured, the separation membrane manufactured and evaluated in Comparative Example 3 was sticky due to the liquid component and dissociated metal salt present in the composite electrolyte coating layer. ) surface characteristics, and thus it has a high adhesive force, indicating that it is unsuitable for processes such as rolling.

11) Mass change measurement

The weight change with time of the composite separator was measured immediately after preparation at a temperature of 25° C. and in the atmosphere. 11 shows the weight change evaluation results according to time of the separation membranes prepared in Examples and Comparative Examples. The separation membrane prepared and evaluated in Example 7 did not show a change in weight over time as there was no liquid component, but the separation membrane manufactured and evaluated in Comparative Example 3 was not affected by volatilization of the liquid component present in the composite electrolyte coating layer. It was confirmed that the weight change with time was observed as a result of the following effects.

12) Infrared spectroscopy

Fourier transform infrared spectroscopy (equipment name: 670-IR, equipment name: 670-IR; Equipment manufacturer: Varian). From the absorption spectrum obtained by spectroscopy of the reflected light when irradiated with infrared rays, it was confirmed that the peak intensity derived from the material properties of the element component derived from the metal salt in the sample can be distinguished and judged.

13) X-ray photoelectron analysis

The composite separator and the anode and cathode facing the composite separator are separated from the electrode assembly in a state where the charging/discharging current is applied and the initial formation process is completed, and each X-ray photoelectron spectroscopy (X-ray Photoelectron Spectroscopy, equipment name: K-Alpha, Equipment manufacturer: Thermo Fisher). From the energy of photoelectrons escaped by X-rays irradiated to the sample, it was confirmed that the presence or absence of the element contained in the element component derived from the metal salt in the sample and the state of chemical bonding can be distinguished and determined.

14) Inductively Coupled Plasma Mass Spectrometry

The composite separator and the anode and cathode facing the composite separator are separated from the electrode assembly in the state where the charging/discharging current is applied and the initial formation process is completed, and each inductively coupled plasma mass spectrometry (Inductively Coupled Plasma Mass Spectromerty, equipment name: ELAN DRC-) II, equipment manufacturer: Perkin Elmer). It was confirmed that the presence or absence and content of elemental components derived from metal salts in the sample could be distinguished and determined by ionizing the elemental components derived from metal salts included in the sample and separating the ions using a mass spectrometer.

15) Nuclear Magnetic Resonance Spectroscopy

The composite separator and the anode and cathode facing the composite separator are separated from the electrode assembly in the state where the charging/discharging current is applied and the initial formation process is completed, and each two-dimensional nuclear magnetic resonance spectroscopy (Nuclear Magnetic Resonance Spectroscopy, equipment name: AVANCE III) HD, equipment manufacturer: Bruker). Using the nuclear magnetic resonance phenomenon of atomic nuclei, which occurs when a magnetic field is applied to elemental elements derived from metal salts included in the sample, information on the chemical environment around the nucleus and spin bonds with neighboring atoms can It was confirmed that the presence or absence and concentration can be distinguished and judged.

16) Time-of-flight secondary ion mass spectrometry

Time-of-flight secondary ion mass spectrometry (Time-of-flight Secondary Ion Mass Spectrometry, Equipment name: TOF-SIMS 5, equipment manufacturer: ION TOF) was performed. Through mass analysis of secondary ions generated in the sample, it was confirmed that the presence or absence and concentration of elemental components derived from metal salts in the sample could be distinguished and determined.

17) Measurement of dissolution rate of composite separator

After measuring the mass (Wdry) of the composite separator prepared in Example, the composite separator was LiPF ₆ at a concentration of 1M in a mixed solvent of 25 ° C. was completely immersed in the dissolved solution) and immersed for 1 hour, then the composite membrane was recovered, dried at 80° C. for 12 hours, and the mass (Wwet) of the dried composite membrane was measured, and the mass and manufacturing of each composite membrane measured The dissolution rate (metal salt dissolution rate) was calculated through the formula (Wwet-Wdry)/Wm x 100(%) using the total mass (Wm) of the metal salts contained in the composite separator in the immediate state. To reduce the measurement error, 20 separators were treated identically, and then Wdry and Wwet were measured for all 20 separators to calculate the dissolution rate.

[Example 1]

1) Preparation of composite separator containing metal salt

Lithium perchlorate was used as a metal salt, and dimethyl carbonate was used as a coating solvent. After 20 wt% of lithium perchlorate was added to dimethyl carbonate, the mixture was stirred at room temperature for 1 hour to prepare a coating solution containing a metal salt.

A coating separator having a ceramic coating layer introduced as a porous substrate (total thickness of 17 μm, fabric thickness of 15 μm, polyethylene, and ceramic coating layers on both sides of 1 μm each) was used. A coating solution containing a metal salt was coated on one surface of the porous substrate using a doctor blade, dried at 60° C. for 1 hour, and the solvent for application was volatilized to prepare a composite separator containing a metal salt. Table 1 shows the content of the metal salt applied to one surface of the porous substrate.

As a result of performing a dissolution rate test of the prepared composite separator, it was confirmed that the metal salt dissolution rate was 65%.

2) Manufacture of lithium ion secondary battery

Production of positive electrode: 96% by weight of lithium-nickel-manganese-cobalt composite oxide (LiNi _0.6 Co _0.2 Mn _0.2 O ₂ ) with an average particle diameter of 5 μm as a positive electrode active material based on 100% by weight of solid content, Super- with an average particle diameter of 40 nm as a conductive material P 2 wt%, polyvinylidene fluoride 2 wt% solid content as a binder, and an organic solvent N-methyl-2-pyrrolidone was added so as to have a solid content of 50 wt% to prepare a positive electrode active material composition (positive electrode mixture slurry) prepared.

The positive electrode active material composition was applied to an aluminum thin film having a thickness of 20 μm using a doctor blade, dried at 120° C., and rolled by a roll press to prepare a positive electrode coated with an active material layer having a thickness of 50 μm. The porosity was 15% by volume.

Preparation of negative electrode: based on 100% by weight of solid content, 96% by weight of natural graphite powder as an anode active material, 2% by weight of carbon black having an average particle diameter of 40nm as a conductive material, 1% by weight of styrene-butadiene rubber as a binder, and 1% by weight of carboxymethyl cellulose as a solid content was added to water to prepare a negative electrode active material composition (negative electrode mixture slurry). The negative active material composition was applied to a copper thin film having a thickness of 20 μm using a doctor blade, dried at 120° C., and rolled by a roll press to prepare a negative electrode coated with an active material layer having a thickness of 65 μm. The porosity was 20% by volume.

Secondary battery production: A battery assembly is prepared by stacking a composite separator including the prepared positive electrode, negative electrode, and metal salt, sealed in a battery case, and 1 mol of LiPF in a solvent mixed with ethylene carbonate and dimethyl carbonate in a 1:1 volume ratio A battery (coin cell and pouch cell) was prepared by injecting a liquid electrolyte in which ₆ was dissolved.

In order to evaluate the physical properties of the manufactured battery, after disassembling the battery in a state where the charging/discharging current was applied and completing the initial formation process, the composite separator and the positive and negative electrodes facing the composite separator were separated from the electrode assembly to measure the physical properties. Then, it is shown in Table 1. The concentration of the electrolyte in the composite separator, the positive electrode and the negative electrode was analyzed using nuclear magnetic resonance spectroscopy, and the measured concentration was verified by separately preparing an electrolyte corresponding to the measured concentration and confirming that the same analysis result was obtained.

[Example 2]

In the same manner as in Example 1, except that the composite separator was prepared using a porous film (polyethylene with a thickness of 9 μm) not introduced with a ceramic coating layer as the porous substrate of the composite separator containing a metal salt in Example 1, a battery (coin) cells and pouch cells) were prepared.

[Example 3]

A battery (coin cell and pouch cell) was prepared in the same manner as in Example 1, except that a composite separator was prepared using lithium trifluoromethanesulfonate as a metal salt in Example 1.

Table 1 by measuring the physical properties of the prepared battery, and the results of evaluating the flame retardancy are shown in FIG. As shown in FIG. 1 , even when a crystalline metal salt containing only a sulfonyl group was formed on the porous substrate, no flame occurred during the flame retardancy test.

As a result of performing a dissolution rate test of the prepared composite separator, it was confirmed that the metal salt dissolution rate was 80%.

[Example 4]

In the same manner as in Example 3, the battery (coin cell) was prepared in the same manner as in Example 3, except that the composite separator was prepared using a porous film (polyethylene with a thickness of 9 μm) to which a ceramic coating layer was not introduced as the porous substrate of the composite separator containing a metal salt. and pouch cells) were prepared.

The results of evaluating the flame retardancy are shown in Table 1 by measuring the physical properties of the prepared battery, and in FIG. 2 . As shown in FIG. 2 , even when a crystalline metal salt containing only a sulfonyl group was coated on a polyethylene porous substrate without a ceramic coating layer, no flame occurred during the flame retardancy test.

[Example 5]

As the coating solution containing the metal salt in Example 1, 20 wt% of lithium trifluoromethanesulfonate, 3.5 wt% of trimethylolpropane ethoxylate triacrylate, and 0.35 wt% of hydroxymethyl phenyl propanone as a photoinitiator A composite separator was prepared in the same manner as in Example 1, except that each material was added to dimethyl carbonate to prepare a coating solution and applied, and then crosslinked by irradiating ultraviolet rays at 2000 mW/cm ² for 20 seconds, and a battery (coin) cells and pouch cells) were prepared.

The results of evaluating the flame retardancy are shown in Table 1 by measuring the physical properties of the prepared battery, and in FIG. 3 . As shown in FIG. 3 , even when a crystalline metal salt containing a sulfonyl group was bound to the porous substrate by a binding component, no flame occurred during the flame retardancy test.

[Example 6]

A battery (coin) in the same manner as in Example 5, except that the composite separator was prepared using a porous film (polyethylene with a thickness of 9 μm) not introduced with a ceramic coating layer as the porous substrate of the composite separator containing a metal salt in Example 5. cells and pouch cells) were prepared.

Table 1 by measuring the physical properties of the prepared battery, and the results of evaluating the flame retardancy are shown in FIG. 4 . As shown in FIG. 4 , even when a crystalline metal salt containing a sulfonyl group was bound by a binding component to a polyethylene porous substrate without a porous inorganic layer, no flame occurred during the flame retardancy test.

[Example 7]

As a coating solution containing a metal salt, silica (SiO ₂ ) 6.65 wt%, polyvinylidene fluoride hexafluoropropylene copolymer (PVDF-HFP) 0.35 wt%, lithium bis(trifluoromethanesulfonyl)imide 20 wt. % and a coating solution containing the remaining amount of acetone was prepared. Polyvinylidene fluoride hexafluoropropylene copolymer, a polymer, was first dissolved in acetone, and then the remaining components were added to the solution according to the ratio.

A porous film (polyethylene with a thickness of 9 μm) without a ceramic coating layer is used as the porous substrate of the composite separator containing a metal salt, and the metal salt is applied to both sides of the porous substrate using the prepared coating solution and dip coating method. A battery (coin cell and pouch cell) was prepared in the same manner as in Example 1, except that a composite separator having a thickness of 13 μm was manufactured by forming a ceramic coating layer containing it.

The results of evaluating the flame retardancy are shown in Table 1 by measuring the physical properties of the prepared battery, and in FIG. 5 . As shown in FIG. 5 , even when the ceramic coating layer was formed on the polyethylene porous film and the crystalline metal salt containing a sulfonyl group in the ceramic coating layer was allowed to bind by the binding component, no flame occurred during the flame retardancy test. In addition, the result of X-ray diffraction pattern for evaluating the crystal characteristics of the prepared separator is shown in FIG. 9, the result of evaluating the adhesive force property is shown in FIG. 10, and the result of evaluating the volatilization property is shown in FIG.

[Example 8]

After preparing a battery assembly in the same manner as in Example 7 and sealing it in a battery case, 1 mol of 1,2-dimethoxy ethane (DME) and 1,3-dioxolane (DOL) was mixed in a solvent in a 1:1 volume ratio. A battery (coin cell and pouch cell) was prepared in the same manner as in Example 7, except that a liquid electrolyte in which LiPF ₆ was dissolved was injected.

The results of evaluating the flame retardancy are shown in Table 1 by measuring the physical properties of the prepared battery, and in FIG. 6 . As shown in FIG. 6 , it can be seen that the prepared composite separator does not generate a flame even if the solvent of the electrolyte in contact in the battery is different, so that the flame retardancy is secured regardless of the sphere type of the solvent.

[Example 9]

After forming the pouch cell prepared in Example 7 twice with a current of 0.1 C (= 0.3 mA/cm 2 ) in a voltage range of 3.0 to 4.2 V, 100 times of charging/discharging cycling with a current of 1.0C is completed. After disassembling the battery of the composite separator, the composite separator, the positive and negative electrodes facing the composite separator were separated from the electrode assembly, and the results of measuring physical properties are summarized in Table 1, and the results of evaluating the flame retardancy are shown in FIG. As shown in FIG. 7 , no flame occurred during the flame-retardant test even when charging and discharging of the battery provided with the manufactured composite separator was repeatedly performed. It can be seen that this is secured.

[Comparative Example 1]

Batteries (coin cells and pouch cells) in the same manner as in Example 1, except that a separator containing no metal salt (total thickness of 17 μm, fabric thickness of 15 μm, polyethylene, and ceramic coating layers on both sides of 1 μm) was used in Example 1 was prepared.

The results of evaluating the flame retardancy are shown in Table 1 by measuring the physical properties of the prepared battery, and the results of evaluating the crystal properties are shown in FIG. 9 . As shown in FIG. 8 , it was confirmed that a flame occurred during the flame retardancy evaluation.

[ Comparative Example 2]

In Comparative Example 1, a battery (coin cell and pouch cell) was prepared in the same manner as in Comparative Example 1, except that a liquid electrolyte in which 2.5M LiPF ₆ was dissolved was injected instead of a liquid electrolyte in which 1 mole of LiPF ₆ was dissolved. .

The physical properties of the prepared battery were measured and shown in Table 1.

[Comparative Example 3]

After dissolving polyethylene oxide at 2% by weight in acetonitrile solvent, 1.5M lithium bis(trifluorosulfonyl) imide (PYR13FSI), an ionic liquid, was added. An electrolyte solution in which methanesulfonyl)imide was dissociated was added. Based on 100 parts by weight of the total weight of the ionic liquid and polyethylene oxide in the composite electrolyte composition, the ionic liquid is 80 parts by weight, and the content of polyethylene oxide is 20 parts by weight.

The composite electrolyte composition was coated on both sides of the porous substrate to a thickness of 5 μm using a dip coating method on a porous film (polyethylene with a thickness of 9 μm), and dried at 60° C. for 1 hour to prepare a composite separator. A battery (coin cell and pouch cell) was prepared in the same manner as in Example 1, except that.

The physical properties of the prepared battery were measured and shown in Table 1, the results of evaluating the crystal properties of the prepared separators in FIG. 9, the results of evaluating the adhesive properties in FIG. 10, and the results of evaluating the volatilization properties in FIG. 11 .

(Table 1)

As can be seen in FIG. 9 (reference, the X-ray diffraction pattern of LiTFSI powder, which is a metal salt used in manufacturing the composite separator, is shown at the bottom) showing the X-ray diffraction measurement results for evaluating the crystallinity, It can be seen that the composite separator prepared in Example 7 contains a metal salt in a crystalline state. In addition, although not shown in the drawings, all of the composite separators prepared in Examples contained metal salts in a crystalline state as in Example 7. It can be confirmed that, when the separator containing the crystalline sulfonyl group-containing metal salt is provided in the battery, excellent flame retardancy is secured as shown in FIGS. 1 to 7 . In addition, as shown in Table 1, it can be seen that when the composite separator contains a crystalline metal salt, both the ion conductivity and the lithium ion migration coefficient increase.

As described above, the present invention has been described with specific details and limited examples and drawings, but these are only provided to help a more general understanding of the present invention, and the present invention is not limited to the above embodiments, and the present invention is not limited to the above embodiments. Various modifications and variations are possible from these descriptions by those of ordinary skill in the art.

Therefore, the spirit of the present invention should not be limited to the described embodiments, and not only the claims described below, but also all of the claims and all equivalents or equivalent modifications to the claims will be said to belong to the scope of the spirit of the present invention. .

Claims (21)

porous substrate; and a crystalline metal salt; a composite separator for an electrochemical device comprising a. The method of claim 1,
The metal salt is a composite separator for an electrochemical device comprising a metal salt containing a sulfonyl group. The method of claim 1,
The porous substrate includes a porous film, and the metal salt is a composite separator for an electrochemical device located on a surface of the porous film. The method of claim 1,
The porous substrate may include a porous film; and a porous coating layer located on at least one surface of the porous film;
The metal salt is a composite separator for an electrochemical device located in at least one of an interface between the porous film and the porous coating layer, an inside of the porous coating layer, and a surface region of the porous coating layer. 5. The method of claim 4,
The porous coating layer is a composite separator for an electrochemical device comprising inorganic particles, organic particles, organic-inorganic composite particles, or mixed particles thereof. 3. The method of claim 2,
The metal salt containing the sulfonyl group is any one or more selected from compounds satisfying the following Chemical Formulas 1 to 4 composite separator for an electrochemical device.
(Formula 1)

(In Formula 1, A ⁺ is a monovalent cation, R ₁ is F, CFH ₂ , CF ₂ H, or C _n F _2n+1 (n is a natural number greater than or equal to 1))
(Formula 2)

(In Formula 2, A ²⁺ is a divalent cation, R ₁ is F, CFH ₂ , CF ₂ H, or C _n F _2n+1 (n is a natural number greater than or equal to 1))
(Formula 3)

(In Formula 3, A ⁺ is a monovalent cation, R ₁ and R ₂ are each independently F, CFH ₂ , CF ₂ H, or C _n F _2n+1 (n is a natural number greater than or equal to 1))
(Formula 4)

(In Formula 4, A ²⁺ is a divalent cation, R ₁ and R ₂ are each independently F, CFH ₂ , CF ₂ H, or C _n F _2n+1 (n is a natural number greater than or equal to 1)) The method of claim 1,
The composite separator is a composite separator for an electrochemical device that is a salt source for supplying the metal salt to an electrolyte provided in the electrochemical device. 7. The method according to any one of claims 1 to 6,
The metal salt is a composite separator for an electrochemical device fixed by any one or more binding components selected from linear polymers and crosslinked polymers. 9. The method of claim 8,
The fixing is a composite separator for an electrochemical device in which a curing component having a curing ability, which is converted into the binding component by curing, is cured in a mixed state with the metal salt. The method of claim 1,
The composite separator is located on one side of the porous substrate and comprises a coating layer containing the metal salt, a composite separator for an electrochemical device. The method of claim 1,
The porous substrate may include a porous film; and a porous coating layer located on at least one surface of the porous film;
The composite separator is located between the porous film and the porous coating layer, the surface region of the porous coating layer, or between the porous film and the porous coating layer and the surface region of the porous coating layer, respectively, comprising a coating layer containing the metal salt Composite separator for electrochemical devices. 12. The method of claim 10 or 11,
The coating layer containing the metal salt is a composite separator for an electrochemical device further containing one or more polymers selected from linear polymers and crosslinked polymers. 12. The method according to any one of claims 1 to 7 and 10 to 11,
The metal salt content, which is the mass of the metal salt per unit area of the porous substrate, is 0.1 to 5.0 mg/cm ² A composite separator for an electrochemical device. 12. The method according to any one of claims 1 to 7 and 10 to 11,
A composite separator for an electrochemical device comprising a metal ion participating in an electrochemical reaction of an electrochemical device provided with the composite separator as an active ion, and the metal ion of the metal salt includes an active ion. The method of claim 1,
A composite separator that satisfies Equation 1 below.
(Equation 1)
5(%) ≤ (Wdry-Wwet)/Wm x 100(%)
(In Equation 1, Wdry is the mass of the composite separator before contact with the electrolyte, and Wwet is a mixed solvent in which ethylene carbonate and dimethyl carbonate are mixed in a volume ratio of 1:1 with LiPF ₆ dissolved at a concentration of 1M. is the mass of the recovered and dried composite membrane after immersing it at 25°C for 1 hour, and Wm is the mass of the metal salt contained in the composite membrane before contact with the electrolyte) After being impregnated in the following reference electrolyte for 1 minute and then recovered, the following flame retardancy is performed at the point in time when the droplet does not fall from the separator to the floor for 1 minute when the gravity direction and the in-plane direction of the separator are positioned in parallel immediately after recovery Flame-retardant separator that does not generate flames from the separator when tested.
Reference electrolyte: mixed solvent of ethylene carbonate and dimethyl carbonate in a volume ratio of 1:1, lithium salt of LiPF ₆ , LiPF ₆ concentration of 1M, temperature of 25℃ ± 5℃
Flame-retardant test: the length of the flame in the air = 5 to 10 cm, the flame tip temperature = 1000 to 1500 ° C, the length of the flame region that is not in contact with the separator when the flame is applied to the separator = 50 to 80% of the length of the flame in the air, the flame moving speed in contact with the separator = 1 to 5 cm/sec An electrochemical device comprising the composite separator for an electrochemical device according to any one of claims 1 to 7 and 10 to 11. 18. The method of claim 17,
An electrochemical device having a metal ion participating in the electrochemical reaction of the electrochemical device as an active ion, and a molar concentration of a salt of the active ion contained in the electrolyte is 0.5 to 6.0M. anode; cathode; a separator interposed between the anode and the cathode; and an electrolyte, wherein the metal ion participating in the electrochemical reaction is used as an active ion, and the electrolyte is a high-concentration electrolyte containing 1M or more of a salt of the active ion, and in a state wetted to the electrolyte, the The ionic conductivity of the separator is 0.3 mS/cm or more, and the ion mobility coefficient of the active ions of the separator is 0.3 or more. An electrochemical module in which two or more electrochemical elements according to claim 19 are electrically connected. A device powered by an energy storage device comprising the electrochemical device according to claim 19 .

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