WO2020054889A1 - Solid polymer electrolyte, electrode structure and electrochemical device comprising same, and method of producing solid polymer electrolyte film - Google Patents

Abstract

Disclosed are a solid polymer electrolyte, an electrode structure comprising same, an electrochemical device comprising same, and a method of producing a solid polymer electrolyte film. The solid polymer electrolyte comprises: a copolymer of crosslinkable monomers including a first ethoxylated pentaerythritol acrylate-based monomer and a second silyl group-containing acrylate-based monomer; and a lithium salt. Thus, the solid polymer electrolyte exhibits high ion conductivity and mechanical strength in a broad range of temperatures including room temperature, and can improve and ensure battery characteristics and reliability. The solid polymer electrolyte can be formed as a free-standing film or formed as a protective film directly coated on a lithium metal electrode, to be usable in an electrochemical device such as a high-density, high-energy lithium-metal battery.

Description

Solid polymer electrolyte, electrode structure and electrochemical device comprising the same, and method for manufacturing solid polymer electrolyte membrane

It relates to a solid polymer electrolyte, an electrode structure and an electrochemical device comprising the same, and a method for manufacturing a solid polymer electrolyte membrane.

In order to respond to the rapidly increasing energy consumption and to change into an environment-friendly consumption form, many studies have been conducted focusing on alternative energy and alternative power sources, that is, electrochemical energy production methods. Many studies have been conducted on lithium secondary batteries, which are known to have the best discharge performance in electrochemical energy.

Unlike a battery using a carbon-based negative electrode such as a lithium ion battery or a conventional lithium polymer battery, in the case of a high-energy-density secondary battery using lithium metal as an electrode, in addition to the separator used as a separator, dentrite on the negative electrode surface A polymer protective layer for suppressing (dendrite) is additionally required. As the protective film, an ion-conducting polymer electrolyte is mainly used, and a polyethylene oxide (PEO) -based polymer is mainly applied for research. However, in the case of PEO, the thermal properties of the polymer itself and low ionic conductivity have little effect as a protective film, and there is a problem that the polymer itself may be damaged by dentrite. To overcome this, there are cases in which a polymer electrolyte membrane other than PEO is used as a protective membrane, but a protective membrane having improved properties has not been developed.

In addition to PEO, polymer electrolyte membranes that have been under research so far include PEO series, polyvinyl acetate (PVA), polyethyleneimine (PEI), polyacrylonitrile (PAN) series, and polyvinylidene fluoride (PVDF). ) These are those that contain as a main component a polymethyl methacrylate (PMMA) -based polymer. However, the ion conductivity of the solid polymer electrolyte membrane made of the polymer is difficult to expect due to the high crystallinity of the polymer itself and the lack of flexibility of the polymer. To overcome this, it is possible to increase the ionic conductivity by lowering the crystallinity and improving the chain mobility of the polymer by expanding the amorphous region of the polymer by using a mixture of materials such as low molecule or oligomer, but in the case of a polymer electrolyte using the above material Compared to liquid electrolytes or gel electrolytes, ionic conductivity is very low.

Accordingly, there is a need to develop a solid polymer electrolyte membrane capable of suppressing crystallinity when using a solid polymer and simultaneously realizing high ionic conductivity and mechanical strength in a wide temperature range.

One aspect of the present invention is to provide a solid polymer electrolyte having high ionic conductivity and mechanical strength in a wide temperature range including room temperature.

Another aspect of the present invention is to provide an electrode structure to which the solid polymer electrolyte is applied.

Another aspect of the present invention is to provide an electrochemical device to which the solid polymer electrolyte is applied.

Another aspect of the present invention is to provide a method for producing a solid polymer electrolyte membrane using the solid polymer electrolyte.

In one aspect of the invention,

A copolymer of a crosslinkable monomer comprising an ethoxylated pentaerythritol acrylate-based first monomer and a silyl group-containing acrylate-based second monomer; And

Lithium salt;

It provides a solid polymer electrolyte comprising a.

In another aspect of the invention,

Lithium metal electrodes; And a protective film including the solid polymer electrolyte disposed on the lithium metal electrode.

In another aspect of the invention,

A lithium secondary battery including the electrode structure is provided.

In another aspect of the invention,

Preparing a precursor solution containing a crosslinkable monomer and a lithium salt comprising an ethoxylated pentaerythritol acrylate-based first monomer and a silyl group-containing acrylate-based second monomer; And

Coating and curing the precursor solution in a film form;

A method of manufacturing a solid polymer electrolyte membrane comprising a.

The solid polymer electrolyte according to an embodiment has a level of ionic conductivity (> 10 ^-5 S / cm) that can be used as a battery material at room temperature, and has excellent mechanical properties of a free standing level. The solid polymer electrolyte may be directly coated on a free standing film or a lithium metal electrode and then molded into a protective film to be used in an electrochemical device such as a high-density high energy lithium metal battery. In addition, by using the solid polymer electrolyte, unlike an electrolyte using a liquid electrolyte, there is no leakage, there are no electrochemical side reactions and electrolyte decomposition reactions occurring at the cathode and the anode, and battery characteristics can be improved and stability can be secured.

1 is a graph showing the results of measuring the ionic conductivity according to the temperature of the solid polymer electrolyte membranes prepared in Examples 1 to 3 and Comparative Examples.

2 is a graph showing the results of measuring the ionic conductivity according to the temperature of the solid polymer electrolyte membrane prepared in Example 1 and Example 4.

The present inventive concept described below can apply various transformations and can have various embodiments. Specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit this creative idea to a specific embodiment, and it should be understood to include all transformations, equivalents, or substitutes included in the technical scope of the creative idea.

The terms used below are only used to describe specific embodiments, and are not intended to limit the creative ideas. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the following, the terms "comprises" or "have" are intended to indicate the presence of features, numbers, steps, actions, components, parts, components, materials or combinations thereof described in the specification, one or more thereof. It should be understood that the above other features, numbers, steps, operations, components, parts, components, materials or combinations thereof are not excluded in advance. "/" Used below may be interpreted as "and" or "or" depending on the situation.

In the drawings, diameters, lengths, and thicknesses are enlarged or reduced to clearly express various components, layers, and regions. The same reference numerals are used for similar parts throughout the specification. When parts of a layer, film, region, plate, etc. are said to be "on" or "above" another part of the specification, this includes not only the case directly above the other part but also another part in the middle. . Throughout the specification, terms such as first and second may be used to describe various components, but the components should not be limited by terms. The terms are used only to distinguish one component from another component. Some of the elements may be omitted from the drawings, but this is for the purpose of understanding the features of the invention and is not intended to exclude the omitted elements.

Unless otherwise specified herein, "substitution" means at least one hydrogen atom is a halogen atom (F, Cl, Br, I), C1 to C20 alkoxy group, nitro group, cyano group, amino group, imino group, azido group, Amidino group, hydrazino group, hydrazono group, carbonyl group, carbamyl group, thiol group, ester group, carboxyl group or salt thereof, sulfonic acid group or salt thereof, phosphoric acid or salt thereof, C1 to C20 alkyl group, C2 to C20 alkenyl group, C2 to C20 alkynyl group, C6 to C20 aryl group, C3 to C20 cycloalkyl group, C3 to C20 cycloalkenyl group, C3 to C20 cycloalkynyl group, C2 to C20 heterocycloalkyl group, C2 to C20 heterocycloalkenyl group , C2 to C20 heterocycloalkynyl group, C3 to C20 heteroaryl group, or a combination thereof.

In addition, unless otherwise specified herein, "hetero" means that at least one hetero atom of N, O, S, and P is included in the formula.

Also, unless otherwise specified in this specification, "(meth) acrylate" means that both "acrylate" and "methacrylate" are possible, and "(meth) acrylic acid" means "acrylic acid" and "methacrylic acid. "It means both are possible.

Hereinafter, exemplary solid polymer electrolytes, electrode structures and electrochemical devices including the same, and methods of manufacturing solid polymer electrolyte membranes will be described in detail with reference to the accompanying drawings.

Solid polymer electrolyte according to one embodiment,

A copolymer of a crosslinkable monomer comprising an ethoxylated pentaerythritol acrylate-based first monomer and a silyl group-containing acrylate-based second monomer; And

Lithium salts.

The solid polymer electrolyte is a crosslinkable monomer, and includes a copolymer crosslinked with an ethoxylated pentaerythritol acrylate-based first monomer and a silyl group-containing acrylate-based second monomer, and a lithium salt, thereby controlling the crystallinity of the polymer to be amorphous. It can maintain the state and improve the ionic conductivity and electrochemical properties. The crosslinked matrix prepared by using the ethoxylated pentaerythritol acrylate-based first monomer and silyl group-containing acrylate-based second monomer as the main skeleton has very low crystallization of the polymer itself and is caused by segmental motion of the polymer in the amorphous region inside. Lithium ions can be freely moved to improve ion conductivity. In addition, the polymer cross-linked structure can improve the high mechanical properties of the copolymer itself, thereby producing a free standing level solid polymer electrolyte membrane.

The ethoxylated pentaerythritol acrylate-based first monomer among the crosslinkable monomers is one of the main components forming a polymer matrix of a solid polymer electrolyte. The ethoxylated pentaerythritol acrylate-based first monomer includes a multifunctional functional group having a crosslinkable functional group of 3 or more.

The ethoxylated pentaerythritol acrylate-based first monomers are ethoxylated pentaerythritol tri (meth) acrylate, ethoxylated pentaerythritol tetra (meth) acrylate, and ethoxylated dipentaerythritol tri (meth) acrylate , At least one selected from the group consisting of ethoxylated dipentaerythritol tetra (meth) acrylate, ethoxylated dipentaerythritol penta (meth) acrylate and ethoxylated dipentaerythritol hexa (meth) acrylate You can.

According to one embodiment, the ethoxylated pentaerythritol acrylate-based first monomer may be represented by Formula 1 below.

[Formula 1]

In Formula 1, R ₁ to R ₄ are each independently hydrogen, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C1-C30 alkoxy group, a substituted or unsubstituted C2-C30 alkenyl group , Substituted or unsubstituted C2-C30 alkynyl group, substituted or unsubstituted C6-C30 aryl group, substituted or unsubstituted C6-C30 aryloxy group, substituted or unsubstituted C7-C30 arylalkyl group, Substituted or unsubstituted C2-C30 heteroaryl group, substituted or unsubstituted C2-C30 heteroaryloxy group, substituted or unsubstituted C3-C30 heteroarylalkyl group, substituted or unsubstituted C4-C30 carbon A cyclic group, a substituted or unsubstituted C5-C30 carbocyclic alkyl group, a substituted or unsubstituted C2-C30 heterocyclic group, or a substituted or unsubstituted C2-C30 heterocyclic alkyl group,

x, y, z, and w are each independently an integer of 1 to 3.

The ethoxylated pentaerythritol acrylate-based first monomer represented by Chemical Formula 1 has four crosslinkable functional groups and can secure higher mechanical strength when crosslinking.

In Chemical Formula 1, R ₁ to R ₄ may be hydrogen.

In Formula 1, x, y, z, and w are each the number of repeating units of ethylene oxide according to ethoxylation, and are each independently an integer of 1 to 3. When the values of x, y, z, and w are 4 or more, the molecular weight is relatively too large, and the crosslinking reaction is slow due to the increase in viscosity of the monomer or there is a possibility of remaining unreacted material, so less than 4 is preferred.

In Formula 1, the sum of x, y, z, and w may be 4 ≤ x + y + z + w ≤ 6. The viscosity of the monomer in the above range is a more appropriate level, and thus a crosslinking reaction can occur smoothly.

The crosslinkable monomer may further include other monomers including a polyfunctional functional group together with the ethoxylated pentaerythritol acrylate-based first monomer.

Other monomers containing such a multifunctional functional group include, for example, acrylates, diacrylates or triacrylates such as trimethylolpropane triacrylate (TMPTA); Dimethacrylate or trimethacrylate such as butanediol dimethacrylate; Diallyl esters or triallyl esters such as diallylserate; Group consisting of ethylene glycol dimethacrylate, tritetraethylene dimethyl acrylate (TTEGDA), glycidyl methacrylate or polyethylene glycol dimethacrylate (PEGDMA), Pentaerythritol triacrylate, Di (trimethylolpropane) tetraacrylate, Glycerol propoxylate triacrylate, etc. One or more selected from can be used.

Other monomers containing the polyfunctional functional group, specifically, for example, diethylene glycol diacrylate (DEGDA), diethylene glycol dimethacrylate (DEGDMA), triethylene glycol diacrylate (TEGDA), triethylene Glycol dimethacrylate (TEGDMA), tetraethylene glycol diacrylate (TTEGDA), glycidyl methacrylate, polyethylene glycol diacrylate (PEGDA), polyethylene glycol dimethacrylate (PEGDMA), polypropylene glycol diacrylate Rate (PPGDA), dipropylene glycol diacrylate (DPGDA), tripropylene glycol diacrylate (TPGDA), diol diacrylate (DDA), diol dimethacrylate (DDMA), ethoxylated trimethylol Ethoxylated trimethylolpropane triacrylate (ETPTA), acrylate-functionalized ethyle ne oxide), butanediol dimethacrylate, ethoxylated neopentyl glycol diacrylate (NPEOGDA), propoxylated neopentyl glycol diacrylate (NPPOGDA), trimethylol Propane triacrylate (TMPTA), trimethylol propane trimethacrylate (TMPTMA), pentaerythritol triacrylate (PETA), ethoxylated propoxylated trimethylolpropane triacrylate (TMPEOTA) / (TMPPOTA) , Propoxylated glyceryl triacrylate, tris (2-hydroxyethyl) isocyanurate triacrylate (THEICTA), pentaerythritol tetraacrylate (PETTA), dipentaerythritol pentaacrylate (DPEPA) , Ditrimethylol propane tetraacrylate (DTMPTTA); Diglycidyl ester, diallylseverate; It may include one or more selected from the group consisting of acrylamide and divinylbenzene.

Among the crosslinkable monomers forming the polymer matrix of the solid polymer electrolyte, the silyl group-containing acrylate-based second monomer has one crosslinkable functional group unlike the first ethoxylated pentaerythritol acrylate-based first monomer.

The silyl group-containing acrylate-based second monomer may control the crosslinking density of the ethoxylated pentaerythritol acrylate-based first monomer and improve elasticity and flexibility of the crosslinked polymer electrolyte. The elasticity of the crosslinked polymer may be increased due to the silyl group included in the second monomer.

The silyl group-containing acrylate-based second monomer may be ethoxylated.

According to an embodiment, the silyl group-containing acrylate-based second monomer may be represented by the following Chemical Formula 2.

[Formula 2]

In Formula 2, R ₁ to R ₄ are each independently hydrogen, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C1-C30 alkoxy group, a substituted or unsubstituted C2-C30 alkenyl group , Substituted or unsubstituted C2-C30 alkynyl group, substituted or unsubstituted C6-C30 aryl group, substituted or unsubstituted C6-C30 aryloxy group, substituted or unsubstituted C7-C30 arylalkyl group, Substituted or unsubstituted C2-C30 heteroaryl group, substituted or unsubstituted C2-C30 heteroaryloxy group, substituted or unsubstituted C3-C30 heteroarylalkyl group, substituted or unsubstituted C4-C30 carbon A cyclic group, a substituted or unsubstituted C5-C30 carbocyclic alkyl group, a substituted or unsubstituted C2-C30 heterocyclic group, or a substituted or unsubstituted C2-C30 heterocyclic alkyl group,

n is an integer from 1 to 4.

In Chemical Formula 2, n is the number of repeating units of ethylene oxide according to ethoxylation, and n may be an integer from 1 to 4. When the value of n is 5 or more, a crosslinking reaction is slow due to an increase in the viscosity of the monomer or there is a possibility of remaining unreacted material. For example, in Chemical Formula 2, n may be an integer from 1 to 3.

In Chemical Formula 2, n may be 1.

According to one embodiment, the silyl group-containing acrylate-based second monomer may be represented by the following Chemical Formula 2a.

[Formula 2a]

In the above formula 2a, n is an integer from 1 to 4.

For example, in Chemical Formula 2a, n may be an integer from 1 to 3.

Examples of the silyl group-containing acrylate-based second monomer include 3- (trimethoxysilyl) methyl acrylate, 3- (trimethoxysilyl) ethyl acrylate, and 3- (trimethoxysilyl) propyl acrylic Rate, 3- (trimethoxysilyl) methyl methacrylate, 3- (trimethoxysilyl) ethyl methacrylate, 3- (trimethoxysilyl) propyl methacrylate, 3- (triethoxysilyl) methyl Acrylate, 3- (triethoxysilyl) ethyl acrylate, 3- (triethoxysilyl) propyl acrylate, 3- (triethoxysilyl) methyl methacrylate, 3- (triethoxysilyl) ethyl methacrylate Acrylate, 3- (triethoxysilyl) propyl methacrylate, 3- [tris (trimethylsiloxy) silyl] propyl methacrylate, and trimethylsilyl crotonate. have.

The weight ratio of the ethoxylated pentaerythritol acrylate-based first monomer and the silyl group-containing acrylate-based second monomer may range from 100: 1 to 1: 1. For example, the weight ratio of the ethoxylated pentaerythritol acrylate-based first monomer and the silyl group-containing acrylate-based second monomer may range from 10: 1 to 1: 1. For example, the weight ratio of the ethoxylated pentaerythritol acrylate-based first monomer and the silyl group-containing acrylate-based second monomer may range from 5: 1 to 1: 1. In the above range

According to one embodiment, the copolymer of the solid polymer electrolyte may further add and copolymerize an oligomer together with the crosslinkable monomer to improve segmental motion of the polymer of the polymer matrix. When the oligomer is added, the flexibility of the chain of the polymer is improved and the interaction between the ions and the polymer is facilitated by the oligomer of the small molecule compared to the polymer, so that the movement of lithium ions can be made faster, thereby the ion conductivity of the solid polymer electrolyte. Can be further improved.

The oligomer usable with the crosslinkable monomer may have a weight average molecular weight (Mw) in the range of 200 to 600. The oligomer may include ether-based, acrylate-based, ketone-based or combinations thereof. In addition, the oligomer may be an alkyl group, an allyl group, a carboxyl group, or a combination thereof. This is because these functional groups are not reactive with lithium metal and are electrochemically stable. On the other hand, a structure in which -OH, -COOH, or -SO ₃ H is included in the terminal group is not suitable. This is because these end groups are reactive with lithium metal and are not electrochemically stable.

As the oligomer, for example, PEG-based diglyme (di-ethylelen glycol), triglyme (tri-ethylelen glycol), tetraglyme (tetra ethylene glycol), or the like can be used.

The amount of the oligomer added may be 1 to 30 parts by weight based on 100 parts by weight of the crosslinkable monomer. In the above range, the properties of the polymer itself and the crosslinked matrix are not loosened, and the mechanical strength, heat resistance, and chemical stability of the polymer can be maintained, and the shape of the polymer film can be stably maintained even at high temperatures.

Lithium salt serves to secure the ion conduction pathway of the solid polymer electrolyte. The lithium salt may be used without limitation as long as it is commonly used in the art. For example, lithium salts include LiSCN, LiN (CN) ₂ , LiClO ₄ , LiBF ₄ , LiAsF ₆ , LiPF ₆ , LiCF ₃ SO ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ F) ₂ , LiSbF ₆ , LiPF ₃ (CF ₂ CF ₃ ) ₃ , LiPF ₃ (CF ₃ ) ₃ and LiB (C ₂ O ₄ ) ₂ It may include one or more selected, but is not limited thereto.

The content of the lithium salt contained in the solid polymer electrolyte is not particularly limited, but may be, for example, 1% to 50% by weight of the total weight of the copolymer and the lithium salt. For example, the content of the lithium salt may be 5% to 50% by weight of the total weight of the copolymer and the lithium salt, specifically 10% to 30% by weight. In the above range, lithium ion mobility and ion conductivity may be excellent.

The solid polymer electrolyte is a crosslinkable monomer, and includes a copolymer crosslinked with an ethoxylated pentaerythritol acrylate-based first monomer and a silyl group-containing acrylate-based second monomer, and a lithium salt, thereby controlling the crystallinity of the polymer to be amorphous. It can maintain the state and improve the ionic conductivity and electrochemical properties. In addition, the polymer cross-linked structure can improve the high mechanical properties of the copolymer itself, thereby producing a free standing level solid polymer electrolyte membrane.

The ion conductivity (σ) of the solid polymer electrolyte may be 1 x 10 ^-5 S / cm to 1 x 10 ^-3 S / cm at room temperature and in a temperature range of 25 ° C to 60 ° C.

As described above, the solid polymer electrolyte has excellent ionic conductivity and mechanical strength and can implement an electrolyte membrane that can be used in electrochemical devices such as high-density high-energy lithium secondary batteries using lithium metal electrodes. In addition, by using the solid polymer electrolyte, there is no leakage, there is no electrochemical side reaction occurring at the cathode and the anode, and unlike the electrolyte using the liquid electrolyte, there is no electrolyte decomposition reaction, and battery characteristics can be improved and stability can be secured.

The electrode structure according to the embodiment,

Lithium metal electrodes; And

And a protective film disposed on the lithium metal electrode and including the above-described solid polymer electrolyte.

The lithium metal electrode may include lithium metal or a lithium metal alloy.

The lithium metal or lithium metal alloy used as the lithium metal electrode has a thickness of 100 µm or less, for example, 80 µm or less, or 50 µm or less, or 30 µm or less, or 20 µm or less. According to another embodiment, the thickness of the lithium metal electrode is 0.1 to 60 μm. Specifically, the thickness of the lithium metal or lithium metal alloy is 1 to 25 μm, for example, 5 to 20 μm.

The lithium metal alloy includes a lithium metal and a metal / semimetal capable of alloying with lithium metal or an oxide thereof. As a metal / semimetal or an oxide thereof capable of alloying with lithium metal, Si, Sn, Al, Ge, Pb, Bi, Sb, and Si-Y alloys (where Y is an alkali metal, alkaline earth metal, group 13 to group 16 element, transition A metal, a rare earth element, or a combination element thereof, not Si), an Sn-Y alloy (where Y is an alkali metal, an alkaline earth metal, a group 13 to 16 element, a transition metal, a rare earth element, or a combination element thereof, Sn Is not), MnOx (0 <x ≤ 2), and the like.

The elements Y are Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ge, P, As, Sb, Bi, S, Se, Te, Po, or a combination thereof. For example, the metal / semimetal oxide capable of alloying with the lithium metal may be lithium titanium oxide, vanadium oxide, lithium vanadium oxide, SnO ₂ , SiO _x (0 <x <2), or the like.

The protective film disposed on the lithium metal electrode includes the above-described solid polymer electrolyte. Since the protective film including the solid polymer electrolyte has high ionic conductivity and mechanical strength even at room temperature and high temperature, it is possible to effectively form an electrode structure applicable to a battery while suppressing dendrites on the surface of the lithium metal electrode.

An electrochemical device according to one embodiment includes the electrode structure.

The telephony device uses the solid polymer electrolyte as a protective film, has excellent safety, has a high energy density, maintains the characteristics of the battery even at a temperature of 60 ° C. or higher, and enables operation of electronic products driven even at such high temperatures. You can.

The electrochemical device may be a lithium secondary battery such as a lithium ion battery, a lithium polymer battery, a lithium air battery, a lithium solid-state battery, and the like.

The electrochemical device to which the solid polymer electrolyte is applied is suitable for applications requiring high-capacity, high-power and high-temperature driving, such as electric vehicles, in addition to existing mobile phones and portable computers, and existing internal combustion engines and fuel cells. , It can be used in hybrid vehicles, etc. in combination with supercapacitors. In addition, the electrochemical device can be used for all other applications requiring high power, high voltage and high temperature driving.

Hereinafter, a method of manufacturing a solid polymer electrolyte membrane according to an embodiment will be described.

A method of manufacturing a solid polymer electrolyte membrane according to one embodiment,

Preparing a precursor solution containing a crosslinkable monomer and a lithium salt comprising an ethoxylated pentaerythritol acrylate-based first monomer and a silyl group-containing acrylate-based second monomer; And

And applying and curing the precursor solution in a film form.

The ethoxylated pentaerythritol acrylate-based first monomer, silyl group-containing acrylate-based second monomer, and lithium salt are as described above.

The precursor solution may further include a crosslinking agent, a photoinitiator, and the like to assist crosslinking of the crosslinkable monomer. The used content of the crosslinking agent, photoinitiator, etc. may be in a conventional range, for example, it may be used in a range of 1 to 5 parts by weight based on 100 parts by weight of the crosslinkable monomer.

When a precursor solution containing a crosslinkable monomer and a lithium salt is prepared, the precursor solution is applied in a film form and cured to form a solid polymer electrolyte membrane.

The method of applying the precursor solution in the form of a film is various and is not particularly limited. For example, the precursor solution may be injected between two glass plates, and a clamp may be applied to the glass plate to apply a constant pressure to control the thickness of the electrolyte membrane. As another example, the precursor solution may be directly coated on a lithium metal electrode using an application device such as spin coating to form a thin film having a predetermined thickness.

As a method of curing the precursor solution, a curing method using heat, UV or high energy radiation (electron beam, γ-ray) may be used. According to one embodiment, a solid polymer electrolyte membrane may be prepared by directly irradiating UV to the precursor solution.

Exemplary embodiments are described in more detail through the following examples and comparative examples. However, the examples are only for illustrating the technical idea, and the scope of the present invention is not limited thereto.

Example 1

As a first ethoxylated pentaerythritol acrylate-based first monomer, 10 g of Pentaerythritol tetraacrylate (PETA) (Sigma-Aldrich, 352.34 g / mol) and 2 g of 3- (Trimethoxysilyl) propyl methacrylate (TMSPMA) as a second acrylate-based acrylate-based monomer After mixing in a vial and stirring for 10 minutes, 0.12 g of lithium salt LiFSI (lithium bis (fluorosulfonyl) imide) was placed in a vial and mixed again. To the mixed mixture, an initiator BEE (Benzoin ethyl ether, Sigma-Aldrich, 240.30 g / mol) was added at 1% based on the total weight of the mixture, followed by stirring and mixing to prepare a gel precursor solution.

After placing 0.2 g of the gel precursor solution on a glass plate and covering it with another prepared glass plate, 365 nm UV was irradiated for 5 minutes to prepare a 20 m thick transparent solid polymer electrolyte membrane.

Example 2

A solid polymer electrolyte membrane was prepared by performing the same procedure as in Example 1, except that the content of the crosslinkable monomer was changed to TETA 8g and TMSPMA 4g.

Example 3

A solid polymer electrolyte membrane was prepared by performing the same procedure as in Example 1, except that the content of the crosslinkable monomer was changed to TETA 6g and TMSPMA 6g.

Example 4

In the same manner as in Example 1, 10 g of TETA and 2 g of TMSPMA were mixed in a vial, stirred for 10 minutes, 2 g of oligomeric triethylene glycol was added and stirred for 3 minutes again, and then 0.14 g of lithium salt LiFSI was placed in a vial and mixed again. .

A solid polymer electrolyte membrane was prepared by performing the same procedure as in Example 1, except that the mixture was used.

Example 5

The gel precursor solution prepared in Example 1 was prepared by using a spin coating rather than pressing between the glass plates in Example 1 to prepare a thin film solid polymer electrolyte membrane. The thickness of the thus prepared film may be applied for a protective film of a lithium metal electrode at a level of about 10 m, and the ion conductivity of the film is unchanged compared to that produced by the compression method of Example 1.

Comparative example

A solid polymer electrolyte membrane made of PEO (MW 1,000,000) to a thickness of 30 m was used as a comparative example.

Evaluation Example 1

The ionic conductivity of the solid polymer electrolyte membranes prepared in Examples 1 to 3 was measured, and the results are shown in Tables 1 and 1 below. Ion conductivity is measured using a Solatron 1260A Impedance / Gain-Phase Analyzer using a Solatron 1260A Impedance / Gain-Phase Analyzer after placing a sample between sus disks using two area 1cm ² sus disks and applying a constant pressure with a spring on both sides. Did.

	Example 1	Example 2	Example 3	Comparative example
TETA / TMSPMA	10g / 2g	8g / 4g	6g / 6g	PEO
Room temperature ion conductivity	6.40E-06	8.50E-06	1.00E-05	1.60E-07

As shown in Table 1, in the case of Examples 1 to 3, the ion conductivity was improved according to the amount of TMSPMA added, but the state of the solid polymer electrolyte membrane after measuring the ion conductivity was the most unchanged in Example 1 In the case of 3, the thickness of the film was relatively thin after the measurement compared to before the measurement. This is considered to be a difference according to the crosslinking density, and in Example 1, the polymer matrix was crosslinked very densely because TETA had the most crosslinkable functional groups, but in Example 3, the crosslinking density was lowered due to the relatively high TMSPMA content and lower crosslinking density. It seems that the ion mobility is improved due to the increase in the mobility of the polymer while the decrease. 1 is a graph measuring the ionic conductivity according to the temperature of the solid polymer electrolyte membranes of Examples 1 to 3 and Comparative Examples under the same conditions.

As shown in FIG. 1, the solid polymer electrolyte membranes of Examples 1 to 3 are superior in ionic conductivity at high temperature as well as at normal temperature as compared to the PEO membranes of Comparative Examples, and in particular have no inflection point due to Tm seen in PEO and stable mechanical properties at 60 ° C. It was shown.

On the other hand, the results of measuring the ion conductivity according to the temperature of the solid polymer electrolyte membranes prepared in Examples 1 and 4 are shown in FIG. 2.

2, when the oligomer is further added to the crosslinkable monomer, it can be seen that the flexibility of the solid polymer electrolyte membrane is increased and the ionic conductivity is improved compared to the case where no oligomer is added.

In the above, a preferred embodiment according to the present invention has been described with reference to the drawings and examples, but this is only an example, and various modifications and equivalent other embodiments are possible from those skilled in the art. Will be able to understand. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims (20)

1. A copolymer of a crosslinkable monomer comprising an ethoxylated pentaerythritol acrylate-based first monomer and a silyl group-containing acrylate-based second monomer; And

   Lithium salt;

   Solid polymer electrolyte comprising a.
2. According to claim 1,

   The ethoxylated pentaerythritol acrylate-based first monomers include ethoxylated pentaerythritol tri (meth) acrylate, ethoxylated pentaerythritol tetra (meth) acrylate, and ethoxylated dipentaerythritol tri (meth) acrylate , At least one selected from the group consisting of ethoxylated dipentaerythritol tetra (meth) acrylate, ethoxylated dipentaerythritol penta (meth) acrylate and ethoxylated dipentaerythritol hexa (meth) acrylate Solid polymer electrolyte.
3. According to claim 1,

   The ethoxylated pentaerythritol acrylate-based first monomer is a solid polymer electrolyte represented by the following Chemical Formula 1:

   [Formula 1]

   

   In Formula 1, R ₁ to R ₄ are each independently hydrogen, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C1-C30 alkoxy group, a substituted or unsubstituted C2-C30 alkenyl group , Substituted or unsubstituted C2-C30 alkynyl group, substituted or unsubstituted C6-C30 aryl group, substituted or unsubstituted C6-C30 aryloxy group, substituted or unsubstituted C7-C30 arylalkyl group, Substituted or unsubstituted C2-C30 heteroaryl group, substituted or unsubstituted C2-C30 heteroaryloxy group, substituted or unsubstituted C3-C30 heteroarylalkyl group, substituted or unsubstituted C4-C30 carbon A cyclic group, a substituted or unsubstituted C5-C30 carbocyclic alkyl group, a substituted or unsubstituted C2-C30 heterocyclic group, or a substituted or unsubstituted C2-C30 heterocyclic alkyl group,

   x, y, z, and w are each independently an integer of 1 to 3.
4. According to claim 3,

   In Formula 1, 4 ≤ x + y + z + w ≤ 6, a solid polymer electrolyte.
5. According to claim 1,

   A solid polymer electrolyte in which the silyl group-containing acrylate-based second monomer is represented by the following Chemical Formula 2:

   [Formula 2]

   

   In Formula 2, R ₁ to R ₄ are each independently hydrogen, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C1-C30 alkoxy group, a substituted or unsubstituted C2-C30 alkenyl group , Substituted or unsubstituted C2-C30 alkynyl group, substituted or unsubstituted C6-C30 aryl group, substituted or unsubstituted C6-C30 aryloxy group, substituted or unsubstituted C7-C30 arylalkyl group, Substituted or unsubstituted C2-C30 heteroaryl group, substituted or unsubstituted C2-C30 heteroaryloxy group, substituted or unsubstituted C3-C30 heteroarylalkyl group, substituted or unsubstituted C4-C30 carbon A cyclic group, a substituted or unsubstituted C5-C30 carbocyclic alkyl group, a substituted or unsubstituted C2-C30 heterocyclic group, or a substituted or unsubstituted C2-C30 heterocyclic alkyl group,

   n is an integer from 1 to 4.
6. According to claim 1,

   The solid polymer electrolyte in which the silyl group-containing acrylate-based second monomer is represented by the following Chemical Formula 2a:

   [Formula 2a]

   

   In the above formula 2a, n is an integer from 1 to 4.
7. According to claim 1,

   The silyl group-containing acrylate-based second monomers are 3- (trimethoxysilyl) methyl acrylate, 3- (trimethoxysilyl) ethyl acrylate, 3- (trimethoxysilyl) propyl acrylate, 3- ( Trimethoxysilyl) methyl methacrylate, 3- (trimethoxysilyl) ethyl methacrylate, 3- (trimethoxysilyl) propyl methacrylate, 3- (triethoxysilyl) methyl acrylate, 3- (Triethoxysilyl) ethyl acrylate, 3- (triethoxysilyl) propyl acrylate, 3- (triethoxysilyl) methyl methacrylate, 3- (triethoxysilyl) ethyl methacrylate, 3- A solid polymer electrolyte comprising at least one selected from the group consisting of (triethoxysilyl) propyl methacrylate, 3- [tris (trimethylsiloxy) silyl] propyl methacrylate, and trimethylsilyl crotonate.
8. According to claim 1,

   The weight ratio of the ethoxylated pentaerythritol acrylate-based first monomer and the silyl group-containing acrylate-based second monomer ranges from 100: 1 to 1: 1.
9. According to claim 1,

   The weight ratio of the ethoxylated pentaerythritol acrylate-based first monomer and the silyl group-containing acrylate-based second monomer ranges from 10: 1 to 1: 1.
10. According to claim 1,

    The crosslinkable monomer is diethylene glycol diacrylate (DEGDA), diethylene glycol dimethacrylate (DEGDMA), triethylene glycol diacrylate (TEGDA), triethylene glycol dimethacrylate (TEGDMA), tetraethylene glycol Diacrylate (TTEGDA), glycidyl methacrylate, polyethylene glycol diacrylate (PEGDA), polyethylene glycol dimethacrylate (PEGDMA), polypropylene glycol diacrylate (PPGDA), dipropylene glycol diacrylate ( DPGDA), tripropylene glycol diacrylate (TPGDA), diol diacrylate (DDA), diol dimethacrylate (DDMA), ethoxylated trimethylolpropane triacrylate (ETPTA), Acrylate-functionalized ethylene oxide, butanediol dimethacrylate, ethoxylate Ethoxylated neopentyl glycol diacrylate (NPEOGDA), propoxylated neopentyl glycol diacrylate (NPPOGDA), trimethylol propane triacrylate (TMPTA), trimethylol propane trimethacryl Rate (TMPTMA), pentaerythritol triacrylate (PETA), ethoxylated propoxylated trimethylolpropane triacrylate (TMPEOTA) / (TMPPOTA), propoxylated glyceryl triacrylate, tris (2 -Hydroxyethyl) isocyanurate triacrylate (THEICTA), pentaerythritol tetraacrylate (PETTA), dipentaerythritol pentaacrylate (DPEPA), ditrimethylol propane tetraacrylate (DTMPTTA); Diglycidyl ester, diallylseverate; A solid polymer electrolyte further comprising at least one selected from the group consisting of acrylamide and divinylbenzene.
11. According to claim 1,

    The copolymer is a solid polymer electrolyte that is copolymerized by further comprising an oligomer in the range of 200 to 600 weight average molecular weight (Mw) with the crosslinkable monomer.
12. The method of claim 11,

    The oligomer is an ether-based, acrylate-based, ketone-based or a combination thereof, and a solid polymer electrolyte comprising an alkyl group, an allyl group, a carboxyl group, or a combination thereof as a functional group.
13. According to claim 1,

    The lithium salt is LiSCN, LiN (CN) ₂ , LiClO ₄ , LiBF ₄ , LiAsF ₆ , LiPF ₆ , LiCF ₃ SO ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ F) ₂ , LiSbF ₆ , LiPF ₃ (CF ₂ CF ₃ ) ₃ , LiPF ₃ (CF ₃ ) ₃ and one or more selected from LiB (C ₂ O ₄ ) ₂ Solid polymer electrolyte containing.
14. According to claim 1,

    Among the total weight of the copolymer and the lithium salt, the content of the lithium salt is 1% to 50% by weight of a solid polymer electrolyte.
15. Lithium metal electrodes; And

    A protective film disposed on the lithium metal electrode, comprising a solid polymer electrolyte according to any one of claims 1 to 14;

    Electrode structure comprising a.
16. An electrochemical device comprising the electrode structure according to claim 15.
17. Preparing a precursor solution containing a crosslinkable monomer and a lithium salt comprising an ethoxylated pentaerythritol acrylate-based first monomer and a silyl group-containing acrylate-based second monomer; And

    Coating and curing the precursor solution in a film form;

    Method for producing a solid polymer electrolyte membrane comprising a.
18. The method of claim 17,

    The ethoxylated pentaerythritol acrylate-based first monomer is a method for preparing a solid polymer electrolyte membrane represented by Formula 1 below:

    [Formula 1]

    

    In Formula 1, R ₁ to R ₄ are each independently hydrogen, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C1-C30 alkoxy group, a substituted or unsubstituted C2-C30 alkenyl group , Substituted or unsubstituted C2-C30 alkynyl group, substituted or unsubstituted C6-C30 aryl group, substituted or unsubstituted C6-C30 aryloxy group, substituted or unsubstituted C7-C30 arylalkyl group, Substituted or unsubstituted C2-C30 heteroaryl group, substituted or unsubstituted C2-C30 heteroaryloxy group, substituted or unsubstituted C3-C30 heteroarylalkyl group, substituted or unsubstituted C4-C30 carbon A cyclic group, a substituted or unsubstituted C5-C30 carbocyclic alkyl group, a substituted or unsubstituted C2-C30 heterocyclic group, or a substituted or unsubstituted C2-C30 heterocyclic alkyl group,

    x, y, z, and w are each independently an integer of 1 to 3.
19. The method of claim 17,

    Method for producing a solid polymer electrolyte membrane wherein the silyl group-containing acrylate-based second monomer is represented by the following Chemical Formula 2:

    [Formula 2]

    

    In Formula 2, R ₁ to R ₄ are each independently hydrogen, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C1-C30 alkoxy group, a substituted or unsubstituted C2-C30 alkenyl group , Substituted or unsubstituted C2-C30 alkynyl group, substituted or unsubstituted C6-C30 aryl group, substituted or unsubstituted C6-C30 aryloxy group, substituted or unsubstituted C7-C30 arylalkyl group, Substituted or unsubstituted C2-C30 heteroaryl group, substituted or unsubstituted C2-C30 heteroaryloxy group, substituted or unsubstituted C3-C30 heteroarylalkyl group, substituted or unsubstituted C4-C30 carbon A cyclic group, a substituted or unsubstituted C5-C30 carbocyclic alkyl group, a substituted or unsubstituted C2-C30 heterocyclic group, or a substituted or unsubstituted C2-C30 heterocyclic alkyl group,

    n is an integer from 1 to 4.
20. The method of claim 17,

    The curing is a method of manufacturing a solid polymer electrolyte membrane is performed using heat, UV or high energy radiation.

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