Electrolyte membrane and method for manufacturing same

Abstract

One aspect of the present invention provides an electrolyte membrane and a method for manufacturing same, the electrolyte membrane comprising: a porous support; and a gel electrolyte filled in pores of the porous support and formed on at least one surface of the porous support. The gel electrolyte includes: a matrix comprising an electrolyte; and a cross-linked body that is cross-linked inside the matrix and supports the matrix, and the cross-linked body is generated by a crosslinking reaction of multifunctional monomers comprising an aromatic unit.

Description

Electrolyte membrane and method for manufacturing the same

[0001] The present invention relates to an electrolyte membrane and a method for manufacturing the same.

[0002] Lithium-ion batteries are widely used as power sources for various electric products requiring miniaturization and lightweight design, such as smartphones, laptops, and tablet PCs. As their application fields expand to include medium and large-sized batteries for smart grids and electric vehicles, there is a demand for the development of lithium-ion batteries with high capacity, long lifespan, and high stability.

[0003] Generally, lithium secondary batteries are manufactured by mounting an electrode assembly, composed of a negative electrode, a positive electrode, and a separator, inside a pouch-type case made of a metal can (such as a cylindrical or prismatic) or an aluminum laminate sheet, and injecting an electrolyte into the electrode assembly. However, since lithium secondary batteries require a case with a fixed volume, such as a cylindrical, prismatic, or pouch type, there are limitations in developing various types of portable devices. Therefore, there is a need for a novel type of lithium secondary battery that allows for easy deformation of its shape. In particular, as an electrolyte for the lithium secondary battery, there is a need for an electrolyte that is free from leakage concerns and possesses excellent ion conductivity.

[0004] Conventionally, liquid electrolytes in which lithium salts are dissolved in non-aqueous organic solvents have been primarily used as electrolytes for lithium secondary batteries. However, such liquid electrolytes have low safety profiles due to the high likelihood of electrode material degradation and organic solvent volatilization, as well as the risk of combustion or explosion caused by rising ambient and battery temperatures and leakage. Consequently, it is difficult to implement various types of lithium secondary batteries.

[0005] Recently, active research on various materials or types of solid electrolytes has been conducted to overcome the safety issues associated with liquid electrolytes. Among these, gel electrolytes utilizing gel-type materials offer the advantages of excellent stability and processability, as well as superior interfacial stability between the electrode and the electrolyte due to the inherent adhesive properties of the gel phase. Currently, most gel electrolytes are manufactured by impregnating a polymer matrix with a high-boiling point organic solvent and fixing it together with a lithium salt, or by injecting a liquid electrolyte. Although these gel electrolytes possess ionic conductivity similar to that of pure liquid electrolytes, they cannot fundamentally be called complete solid electrolytes because they contain a liquid electrolyte, and they still pose risks of fire and explosion.

[0006] Meanwhile, gel electrolytes can be prepared by gelling (crosslinking) a composition comprising a lithium salt, an organic solvent, a polymerizable monomer, and an initiator at an appropriate temperature and time. Through such gel electrolytes, stability issues such as leakage and explosion, as well as processability and moldability, can be improved. However, gel electrolytes prepared by the above method have very low ionic conductivity at room temperature, making them difficult to apply to actual batteries.

[0007] Korean Registered Patent No. 10-1648465 discloses that the electrochemical properties of a gel polymer electrolyte can be improved by including a crosslinked polymer matrix formed by the crosslinking of three or more different crosslinkable monomers, but although the gel polymer electrolyte contributed to some extent to the improvement of ion conductivity or stability, the effect was weak. In addition, gel electrolytes have problems such as poor flame retardancy and mechanical strength due to the material properties, and difficulty in thinning them into thin films, which are hindering the high performance, long lifespan, and practical application of lithium secondary batteries.

[0008] In addition, Korean published patents No. 10-2020-0174552, No. 10-2022-0151618, No. 10-2022-0124997, etc. disclose that an electrolyte membrane comprises a porous support and a gel electrolyte formed on at least one surface of the porous support, which is filled in the pores of the porous support, and that the gel electrolyte comprises a matrix containing the electrolyte and a crosslinker of a polyfunctional aliphatic monomer that is crosslinked inside the matrix to support the matrix, thereby enabling balanced realization and improvement of ion conductivity, mechanical properties, and heat resistance. However, there is a problem in that the gel electrolyte formed to a predetermined thickness on the surface of the porous support penetrating the porous support is easily peeled off due to physical or chemical factors.

[0009] The present invention aims to solve the problems of the aforementioned prior art. The objective of the present invention is to provide an electrolyte membrane and a method for manufacturing the same that can balance ion conductivity and mechanical properties while simultaneously strengthening the bonding strength between a porous support and a gel electrolyte.

[0010] One aspect of the present invention provides an electrolyte membrane comprising: a porous support; and a gel electrolyte formed on at least one surface of the porous support and filled in the pores of the porous support, wherein the gel electrolyte comprises a matrix containing an electrolyte and a crosslinker that is crosslinked within the matrix and supports the matrix, and wherein the crosslinker is produced by a crosslinking reaction of a polyfunctional monomer containing an aromatic unit.

[0011] In one embodiment, the polyfunctional monomer may have a structure according to the following chemical formula 1.

[0012] <Chemical Formula 1>

[0013]

[0014] In the above chemical formula 1, Ar is an aromatic unit, R1 and R2 are each an acrylate group, methacrylate group, vinyl group, or allyl group containing a crosslinking reactive double bond, AO1 and AO2 are each an alkylene oxide group, m and n are each integers greater than or equal to 0, and m+n is greater than or equal to 1.

[0015] In one embodiment, the aromatic unit may have a bisphenol A structure.

[0016] In one embodiment, the content of the crosslinker in the gel electrolyte may be 10 to 30 weight percent.

[0017] In one embodiment, the porous support may comprise one selected from the group consisting of polyethylene, polypropylene, polybutylene, polymenylpentene, ethylene vinyl acetate, ethylene butyl acrylate, ethylene ethyl acrylate, and a combination or copolymer of two or more of these.

[0018] In one embodiment, the porous support may further include an inorganic filler.

[0019] In one embodiment, the porosity of the porous support is 30 to 90%, the average pore size is 20 to 100 nm, the thickness is 1 to 20 μm, and the filling rate of the gel electrolyte into the pores of the porous support may be 90% or more.

[0020] In one embodiment, the thickness of the gel electrolyte formed on at least one surface of the porous support may be 0.1 to 50 μm.

[0021] In one embodiment, the electrolyte is a lithium salt solution, and the lithium salt solution may include a lithium salt and a glycol ether-based solvent having a boiling point of 110°C or higher.

[0022] In one embodiment, the ionic conductivity of the electrolyte membrane is 0.3 mS / cm or higher, and the pencil hardness of the gel electrolyte formed on at least one surface of the porous support, measured according to ASTM D3363, may be 3B or higher.

[0023] Another aspect of the present invention provides a method for manufacturing an electrolyte membrane comprising: (a) applying an electrolyte solution to one side of a first release film to create a first electrolyte layer in a non-gelled state; (b) laminating a porous support on the first electrolyte layer; (c) applying an electrolyte solution to the porous support to create a second electrolyte layer in a non-gelled state; (d) laminating a second release film on the second electrolyte layer, and then pressing the first and second release films to penetrate the first and second electrolyte layers into the pores of the porous support and integrate them; (e) applying energy to the integrated first and second electrolyte layers to crosslink the first and second electrolyte layers; and (f) removing the first and second release films.

[0024] An electrolyte membrane according to one aspect of the present invention comprises: a porous support; and a gel electrolyte formed on at least one surface of the porous support and filled into the pores of the porous support, wherein the gel electrolyte comprises a matrix containing an electrolyte and a crosslinking agent that is crosslinked within the matrix and supports the matrix, and by applying a crosslinking agent produced by a crosslinking reaction of a polyfunctional monomer containing an aromatic unit, the ionic conductivity and mechanical properties can be balanced, and the bonding strength between the porous support and the gel electrolyte can be strengthened.

[0025] The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description or claims of the present invention.

[0026] FIG. 1 is a schematic diagram of a method for manufacturing an electrolyte membrane according to one embodiment of the present invention.

[0027] FIG. 2 is an optical microscope (200x magnification) image of the surface of an electrolyte membrane according to an embodiment and a comparative example of the present invention.

[0028] The present invention will be described below with reference to the attached drawings. However, the present invention may be implemented in various different forms and is therefore not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification have been given similar reference numerals.

[0029] Throughout the specification, when it is stated that a part is "connected" to another part, this includes not only cases where they are "directly connected," but also cases where they are "indirectly connected" with other members interposed between them. Furthermore, when it is stated that a part "includes" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but rather allows for the inclusion of additional components.

[0030] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

[0031] electrolyte membrane

[0032] One aspect of the present invention provides an electrolyte membrane comprising: a porous support; and a gel electrolyte formed on at least one surface of the porous support and filled in the pores of the porous support, wherein the gel electrolyte comprises a matrix containing an electrolyte and a crosslinker that is crosslinked within the matrix and supports the matrix, and wherein the crosslinker is produced by a crosslinking reaction of a polyfunctional monomer containing an aromatic unit.

[0033] The porous support can fix and support the gel electrolyte in the electrolyte membrane to compensate for the weak mechanical properties and stability of the gel electrolyte. The gel electrolyte can be filled into the pores of the porous support, preferably the internal pores located in the center of the porous support, as well as formed on the surface of the porous support with a predetermined thickness.

[0034] The above electrolyte membrane can overcome the physical and mechanical limitations of the gel electrolyte while simultaneously improving the conductivity and stability of the electrolyte membrane based on the organic interaction between the porous support and the gel electrolyte. Specifically, the porous support can act as a structure that compensates for the weak mechanical strength and thermal stability of the gel electrolyte by fixing and supporting the gel electrolyte. In particular, since the gel electrolyte is not merely formed on the surface of the porous support but penetrates and fills into the central pores located inside the porous support, a uniform and continuous ion conduction pathway can be secured across the entire region of the electrolyte membrane. This can contribute to suppressing the phenomenon of the gel electrolyte detaching or peeling off within the porous support, while simultaneously improving adhesion stability with the electrode, airtightness, and flame retardancy.

[0035] In addition, by inducing the formation of a mechanical reinforcement structure during the gelation (crosslinking) process of the gel electrolyte, the crosslinking agent, which is a component of the gel electrolyte, can combine with the lattice structure inside the porous support to achieve structural integration. In particular, by crosslinking the gel electrolyte using a polyfunctional monomer containing aromatic units, the crosslinking network formed internally within the gel electrolyte can be stably maintained inside and on the surface of the porous support. This increases the deformation resistance of the gel electrolyte and enables the electrolyte membrane to function stably without physical destruction or performance degradation even under operating environments inside the battery (high temperature, high current, etc.). The simultaneous realization of such mechanical stability and conductivity can serve as an important foundation for the electrolyte membrane to exhibit superior performance compared to conventional liquid electrolytes or general gel electrolyte-based secondary batteries.

[0036] The porous support may include a plurality of pores with substantially uniform average size, and these pores may contribute to improving the resistance characteristics and ion conductivity of the separator. In addition, the separator can be made into a thin film of the required thickness due to its high porosity and high mechanical strength.

[0037] The porosity of the porous support may be 30 to 90%, preferably 30 to 80%, and more preferably 30 to 70%. As used herein, the term "porosity" refers to the ratio of the volume occupied by pores to the total volume in any porous article. If the porosity of the porous support is less than 30%, air permeability and ion conductivity may be reduced, and if it exceeds 90%, mechanical properties such as tensile strength and puncture strength may be reduced.

[0038] The porosity of the porous support is one of the factors determining the electrochemical performance and mechanical stability of the electrolyte membrane. By controlling the porosity of the porous support to the aforementioned range, the porous support can maintain structural integrity and durability while inducing sufficient impregnation of the electrolyte. If the porosity is excessively low, the electrolyte cannot penetrate into the porous support, which may limit the formation of continuous conductive paths within the electrolyte membrane. This leads to a decrease in the overall ionic conductivity of the electrolyte membrane and limits the interfacial contact area with the electrode, negatively affecting the efficiency and output characteristics of the battery. Conversely, if the porosity is excessively high, while the impregnation of the electrolyte may be improved, the physical strength of the porous support itself is weakened, making it difficult to ensure the mechanical reliability of the electrolyte membrane. In particular, if mechanical properties such as tensile strength and puncture strength deteriorate, the risk of damage to the electrolyte membrane under external stress, compressive force, or thermal expansion increases, which can directly lead to reduced battery lifespan and safety issues. Therefore, by considering the trade-off between ion conductivity and mechanical strength, and by optimizing the porosity of the porous support to within a certain range, it is possible to simultaneously secure the impregnation stability of the gel electrolyte and the physical robustness of the structure.

[0039] The average size of the pores included in the porous support may be 20 to 100 nm, preferably 20 to 80 nm, more preferably 30 to 60 nm. If the average size of the pores is less than 20 nm, air permeability and ion conductivity may be reduced, and if it is greater than 100 nm, mechanical properties such as tensile strength and puncture strength may be reduced.

[0040] The average size of the pores contained in the porous support acts as another important design variable in quantitatively balancing the ion conductivity characteristics and mechanical stability of the electrolyte membrane. If the average size of the pores contained in the porous support is excessively small, the penetration of the gel electrolyte is restricted as the diameter of the pores themselves decreases, and the retention space of the gel electrolyte penetrated by the capillary effect is also reduced, making it difficult to continuously form a conductive path of the electrolyte membrane. As a result, the overall ion conductivity decreases, and there is a risk that the output characteristics of the battery will deteriorate as the electrolyte membrane fails to function effectively at the interface with the electrode. Conversely, if the average size of the pores contained in the porous support is excessively large, the penetration and capture efficiency of the gel electrolyte may be improved, but the mechanical rigidity of the entire structure of the porous support may decrease as the pores become excessively large. Specifically, as the density of the inter-pore connection structure decreases and the load-bearing capacity per unit area is reduced, mechanical properties such as tensile strength and puncture strength may deteriorate. This causes structural vulnerabilities that make the electrolyte membrane susceptible to damage from external impacts, compressive stress, or temperature changes, and can act as a factor that lowers the durability and reliability of the entire battery system, including the electrolyte membrane.

[0041] The thickness of the porous support may be 1 to 20 μm, preferably 5 to 15 μm, more preferably 5 to 12 μm, in terms of thinning and increasing energy density of the electrochemical device. If the thickness of the porous support is less than 1 μm, mechanical properties may be degraded, and if it exceeds 20 μm, air permeability and ion conductivity may be degraded.

[0042] The thickness of the porous support described above can directly influence not only the overall performance of the electrolyte membrane but also the miniaturization, weight reduction, and high energy density of the electrochemical device containing it. This thickness range is designed as an optimal condition that ensures the penetration and immobilization of the gel electrolyte within the pores while minimizing the overall thickness of the electrolyte membrane to shorten the ion diffusion distance and maximize energy storage efficiency. In particular, the thin film structure can improve high-speed charge / discharge characteristics by reducing ion transport resistance, and minimize conduction losses at the electrode-electrolyte interface by improving adhesion to the electrode. Consequently, the electrochemical performance of the electrolyte membrane is enhanced, providing favorable conditions for realizing high-performance secondary batteries.

[0043] If the thickness of the porous support becomes excessively thin, less than 1 μm, structural stability is not ensured, which can lead to a rapid deterioration of mechanical properties such as tensile strength and puncture strength. Such thin-film supports are highly susceptible to damage during manufacturing and assembly processes, or to cracking and failure caused by physical impact or thermal stress in actual usage environments. This can lead to functional loss of the electrolyte membrane and a decrease in the overall reliability of the battery. Conversely, if the thickness of the porous support exceeds 20 μm, it is difficult for the gel electrolyte to be uniformly impregnated throughout the entire interior of the porous support. Consequently, residual spaces or unfilled regions exist within the pores, which may result in discontinuities in the ion conduction pathways within the electrolyte membrane. Furthermore, a thick support increases the ion diffusion distance, thereby raising the internal resistance of the battery and causing a decrease in the density of storage capacity relative to the total volume.

[0044] At least 90%, preferably at least 95%, and more preferably at least 99% of the total volume of the pores of the porous support can be completely impregnated and filled by the gel electrolyte. If the filling rate of the gel electrolyte into the pores of the porous support is less than 90%, the gel electrolyte cannot be continuously formed from one side to the other of the porous support, and in this case, the conductive path by the gel electrolyte is blocked in at least some area of ​​the electrolyte membrane, making it difficult to secure the required level of ion conductivity.

[0045] The above electrolyte membrane is formed by filling the gel electrolyte within the pores of the porous support, wherein the filling rate of the gel electrolyte acts as a factor for ensuring the functionality and reliability of the electrolyte membrane. This high-filling structure ensures that ion conduction pathways are formed continuously without interruption within the electrolyte membrane and enables uniform electrolyte contact across the entire interface with the electrode, thereby simultaneously improving the output stability and energy efficiency of the battery. In particular, as the gel electrolyte penetrates and becomes fixed to the central pores of the porous support, mechanical stability and electrical continuity are ensured throughout the electrolyte membrane, allowing the structural integrity of the electrolyte membrane to be maintained even under harsh operating conditions such as high temperature and high current. Furthermore, the high filling rate significantly reduces the possibility of electrolyte evaporation or degradation due to external environmental factors, thereby contributing to the long-term durability of the electrolyte membrane and the improvement of battery life.

[0046] Conversely, if the filling rate of the gel electrolyte is lower than 90%, the electrolyte cannot be continuously formed from one side to the other of the porous support, and voids or unfilled regions exist within the pores. This incomplete filling results in the interruption of conductive paths within the electrolyte membrane, and the electrolyte is not sufficiently distributed at some contact surfaces with the electrode, preventing smooth charge transfer. Consequently, ion conductivity may decrease in specific areas within the battery, or electrochemical reactions may be locally restricted, leading to problems such as heat generation, inefficient discharge, and even cell imbalance or thermal runaway. Furthermore, if the gel electrolyte is not completely fixed within the pores, the electrolyte may move or delaminate within the separator structure due to external shocks or minute vibrations during long-term operation. This weakens the mechanical stability of the electrolyte membrane and can accelerate structural damage or degradation during repeated charge-discharge cycles.

[0047] The above electrolyte membrane can be formed such that the gel electrolyte penetrates the pores of the porous support and is applied to at least a portion of its surface, thereby improving the ion conductivity of the electrolyte membrane and enabling uniform ion conductivity across the entire surface of the electrolyte membrane. The thickness of the gel electrolyte formed on at least one surface of the porous support may be 0.1 to 50 μm, preferably 0.1 to 20 μm, more preferably 0.1 to 10 μm, or 0.1 to 5 μm. The gel electrolyte formed on at least one surface of the porous support can improve ion conductivity by providing a continuous conductive path at the interface between the electrolyte membrane and the electrode, and the polymer crosslinked material included in the gel electrolyte can improve the airtightness and safety of the electrolyte membrane and the electrochemical device containing it by providing a necessary level of adhesion to the electrode.

[0048] The above electrolyte membrane can be designed to maximize interfacial characteristics with the electrode by including a gel electrolyte formed with a certain thickness not only within the pores of the porous support but also on at least one surface thereof. Such a thin film structure is effective in improving the ion conductivity and interfacial reaction efficiency of the entire electrolyte membrane by preventing an increase in ion resistance due to excessive thickness while maintaining adhesion to the electrode surface. In particular, since the gel electrolyte exists in the form of a continuous film on the surface, it can maintain connectivity with the electrolyte filled in the internal pores of the porous support and induce uninterrupted movement of ions across the entire region of the electrolyte membrane. This enables the electrolyte membrane to function not merely as a medium for ions, but as an active medium that forms and maintains an interfacial conduction path with the electrode.

[0049] In addition, the polymer crosslinker contained in the gel electrolyte formed on the surface of the porous support goes beyond being a simple filler and plays a role in substantially strengthening the interfacial bonding force between the electrolyte membrane and the electrode. If the adhesion between the electrode and the electrolyte membrane is insufficient, various problems may arise, such as separation at the interface during repeated charge-discharge cycles or the penetration of external substances, such as gas or moisture, through the interface. To prevent this, the gel electrolyte on the surface can be stably attached to the electrode through a crosslinking reaction using a polyfunctional monomer containing aromatic units. As a result, the electrolyte membrane can secure sufficient airtightness at the interface with the electrode, and its resistance to changes in the external environment can also be improved.

[0050] The above-mentioned polyfunctional monomer may have a structure according to the following chemical formula 1.

[0051] <Chemical Formula 1>

[0052]

[0053] In the above chemical formula 1, Ar is an aromatic unit, R1 and R2 are each an acrylate group, methacrylate group, vinyl group, or allyl group containing a crosslinking reactive double bond, AO1 and AO2 are each an alkylene oxide group, m and n are each integers greater than or equal to 0, and m+n is greater than or equal to 1.

[0054] The polyfunctional monomer having a structure according to Chemical Formula 1 above is, for example, bisphenol A ethoxylate diacrylate (BPA(EO)nDA), bisphenol A ethoxylate dimethacrylate (BPA(EO)nDMA), bisphenol A ethoxylate divinyl ether (BPA(EO)nDVE), bisphenol A ethoxylate diallyl ether (BPA(EO)nDAE), bisphenol F ethoxylate diacrylate (BPF(EO)nDA), bisphenol F ethoxylate dimethacrylate (BPF(EO)nDMA), bisphenol F ethoxylate divinyl ether (BPF(EO)nDVE), bisphenol F ethoxylate diallyl ether (BPF(EO)nDAE), bisphenol A propoxylate diacrylate (BPA(PO)nDA), bisphenol A propoxylate Dimethacrylate (BPA(PO)nDMA), Bisphenol A Propoxylate Divinyl Ether (BPA(PO)nDVE), Bisphenol A Propoxylate Diallyl Ether (BPA(PO)nDAE), Bisphenol F Propoxylate Diacrylate (BPF(PO)nDA), Bisphenol F Propoxylate Dimethacrylate (BPF(PO)nDMA), Bisphenol F Propoxylate Divinyl Ether (BPF(PO)nDVE), Bisphenol F Propoxylate Diallyl Ether (BPF(PO)nDAE), Resorcinol Ethoxylate Diacrylate (RE(EO)nDA), Resorcinol Ethoxylate Dimethacrylate (RE(EO)nDMA), Hydroquinone Ethoxylate Diacrylate (HQ(EO)nDA), Hydroquinone Ethoxylate It may be one selected from the group consisting of dimethacrylate (HQ(EO)nDMA) and combinations of two or more of these, but is not limited thereto.

[0055] The above aromatic unit may have a bisphenol A structure, and in this case, the polyfunctional monomer may be bisphenol A ethoxylate diacrylate and / or bisphenol A ethoxylate dimethacrylate having a structure according to the following chemical formula 2.

[0056] <Chemical Formula 2>

[0057]

[0058] In the above chemical formula 2, m+n represents the number of ethylene oxide repeating units, and the number of ethylene oxide repeating units may have a direct or indirect effect on the ionic conductivity and durability of the bisphenol A ethoxylate diacrylate, the gel electrolyte, and the electrolyte membrane containing the same. For example, in the above chemical formula 2, m and n are each integers greater than or equal to 0, and m+n may be greater than or equal to 1, greater than or equal to 2, greater than or equal to 3, greater than or equal to 4, greater than or equal to 6, greater than or equal to 10, greater than or equal to 20, greater than or equal to 30, and the upper limit is not particularly limited, but may be less than or equal to 100, less than or equal to 90, less than or equal to 80, less than or equal to 70, less than or equal to 60, less than or equal to 50, or less than or equal to 40. Preferably, in the above chemical formula 2, m and n are each integers greater than or equal to 0, and m+n may be 3 to 30, 4 to 30, or 10 to 30. In the above chemical formula 2, if m+n is less than 3, the flexibility of the gel electrolyte and the electrolyte membrane containing it may be reduced, and if it is greater than 30, the time required for the cross-linking reaction of the polyfunctional monomer, i.e., gelation, may be prolonged, which may reduce productivity.

[0059] The polyfunctional monomer according to Chemical Formula 2 above has a bisphenol A-based ethoxylate structure, and the number of repeating units (m+n) of the ethoxylate chain can affect the physical properties of the gel electrolyte, namely flexibility and crosslinking reactivity. Generally, as the number of repeating units of the ethoxylate increases, the flexibility of the polymer chain improves, thereby improving the overall ductility and elasticity of the gel electrolyte. This contributes to the electrolyte membrane maintaining structural stability even under various external stresses or expansion and contraction environments. On the other hand, if the number of repeating units becomes excessively small, the rigidity of the polymer chain increases, leading to reduced flexibility. Consequently, problems may arise where the entire electrolyte membrane cracks easily or it becomes difficult to ensure contact stability with the electrode interface.

[0060] More specifically, if the sum of m+n in Chemical Formula 2 above is less than 3, the overall chain length of the polymer matrix is ​​short, which limits the molecular fluidity of the crosslinker and consequently impairs the flexibility of the gel electrolyte. A gel electrolyte with reduced flexibility may easily break or delaminate at the interface with a porous support due to repeated charge-discharge cycles or external mechanical vibrations, thereby shortening the reliability and lifespan of the electrolyte membrane. Furthermore, such structural fragility negatively affects the interfacial adhesion with the electrode, which can consequently lead to a degradation of electrochemical performance. Therefore, by setting m+n to be at least 3, the gel electrolyte possesses sufficient flexibility and resilience, and simultaneously ensures the mechanical durability and interfacial stability of the electrolyte membrane.

[0061] On the other hand, if the value of m+n exceeds 30, the number of ethoxylate repeating units becomes excessive, resulting in excessively long polymer chains and increased fluidity. Such a structure leads to reduced reactivity in the progression of the polymer crosslinking reaction and significantly increases the time required to complete the actual gelation reaction. This not only lowers the productivity of the entire manufacturing process but also causes increased costs and energy consumption during the process of scaling up to an industrial scale. For example, if the gelation time is prolonged, the time and intensity required for UV irradiation or heat treatment processes must be increased, which may make it difficult to ensure the uniformity of electrolyte membrane quality. Furthermore, excessively long chains can reduce the density of crosslinking bonds, potentially degrading the performance of the gel electrolyte in terms of mechanical integrity and ion conductivity.

[0062] The above crosslinker may be produced by a crosslinking reaction of the polyfunctional monomer activated by an initiator. The type of initiator is not particularly limited, as long as it is capable of imparting radicals to the polyfunctional monomers and inducing a crosslinking reaction between the polyfunctional monomers by the radicals.

[0063] The above-mentioned polyfunctional monomer is capable of being activated and crosslinked by energy, such as heat, light, or a combination thereof, in the presence of an initiator, and is not particularly limited in type as long as it has the structure of Formula 1 and / or Formula 2. The above-mentioned polyfunctional monomer may have two or more functional groups per molecule, preferably two to six. If the number of functional groups per molecule of the above-mentioned polyfunctional monomer is less than two, crosslinking may be delayed, and if it exceeds six, it is difficult to control crosslinking.

[0064] The content of the crosslinker in the gel electrolyte may be 10 to 30 weight percent. If the content of the crosslinker in the gel electrolyte is less than 10 weight percent, the binding strength of the gel electrolyte in the electrolyte membrane may be reduced, and if it exceeds 30 weight percent, the ionic conductivity may be reduced.

[0065] The gel electrolyte comprises a polymer crosslinker formed through a crosslinking reaction within a matrix containing the electrolyte, and the polymer crosslinker can determine the structural stability and mechanical properties of the electrolyte membrane. In particular, since the content of the crosslinker in the gel electrolyte has a direct or indirect effect on the performance of the electrolyte membrane, the content needs to be precisely controlled. By setting the content of the crosslinker in the gel electrolyte to a range of 10 to 30 weight percent, the balance between ion conductivity and mechanical strength can be optimized. Within this range, the crosslinker enables the gel electrolyte to be effectively fixed within the porous support, and also allows the gel electrolyte layer formed on the surface to exhibit sufficient adhesion at the interface with the electrode. As a result, the entire electrolyte membrane can maintain a stable structure even in repetitive environments such as charge and discharge cycles, and an electrochemical device with high power output and long lifespan characteristics can be realized.

[0066] Meanwhile, if the content of the crosslinker is set to less than 10% by weight, the physical integrity of the gel electrolyte may be incompletely formed, which can significantly reduce the bonding strength and interfacial stability of the electrolyte membrane. Specifically, as the density of the gel structure formed through the crosslinking reaction decreases, the gel electrolyte may easily peel off from within the porous support, or the surface gel electrolyte layer may detach during the electrochemical reaction at the contact surface with the electrode. Furthermore, if the degree of crosslinking is low, resistance to external shocks or thermal expansion and contraction caused by temperature changes is weakened, and the likelihood of structural damage to the electrolyte membrane during battery operation increases. This can lead to various electrochemical instabilities such as reduced battery output, internal short circuits, and leakage, and these problems may become more pronounced, particularly under high voltage and high current conditions.

[0067] Conversely, if the content of the crosslinker in the gel electrolyte exceeds 30% by weight, the density of the gelation reaction becomes excessively high, causing a rapid decrease in the flexibility of the electrolyte and resulting in the electrolyte membrane exhibiting brittle characteristics. Furthermore, an excessive crosslinking structure can physically block or restrict the movement paths of ions within the electrolyte, thereby reducing ion conductivity. This prevents smooth charge transfer between electrodes, increasing the overall cell resistance and potentially causing side effects such as overheating or reduced output during high-speed charging and discharging. Additionally, if the gel electrolyte becomes excessively hardened and loses its elasticity, it fails to absorb interfacial stress generated by the expansion and contraction of the electrodes, leading to cracking or interfacial detachment, which can shorten the cell lifespan.

[0068] The porous support may include a polymer resin having electrical insulation properties, and the polymer resin may include a thermoplastic resin considering shutdown characteristics. The term "shutdown characteristic" as used herein means that when a battery overheats and its temperature rises, the polymer resin melts and closes the pores of the porous support, thereby blocking the movement of ions. In this regard, the melting point of the polymer resin or the thermoplastic resin may be 200°C or lower.

[0069] The above thermoplastic resin may include, for example, one selected from the group consisting of polyethylene, polypropylene, polybutylene, polymenylpentene, ethylene vinyl acetate, ethylene butyl acrylate, ethylene ethyl acrylate, and combinations or copolymers of two or more of these, preferably may include at least one of polyethylene and polypropylene, and more preferably may include polyethylene.

[0070] The above polyethylene may be one selected from the group consisting of ultra-high molecular weight polyethylene (UHMWPE, Mv: 1,000,000–7,000,000 g / mol), high molecular weight polyethylene (HMWPE, Mv: 100,000–1,000,000 g / mol), high-density polyethylene (HDPE, Mv: 100,000–1,000,000 g / mol), low-density polyethylene (LDPE, Mv: 10,000–100,000 g / mol), homogeneous linear and linear low-density polyethylene (LLDPE), and combinations of two or more of these. Here, the viscosity-average molecular weight (Mv) is an average molecular weight calculated based on the viscosity of the polymer solution and can be determined experimentally using the Mark-Houwink equation.

[0071] For example, the polyethylene may be high-density polyethylene with a viscosity-average molecular weight (Mv) of 250,000 to 800,000 g / mol. If the viscosity-average molecular weight of the polyethylene exceeds 800,000 g / mol, the viscosity increases and processability may decrease, and if it is less than 250,000 g / mol, the viscosity becomes excessively low, which drastically reduces dispersibility with pore-forming agents, antioxidants, etc. used when manufacturing porous supports, and in some cases, phase separation or layer separation may occur.

[0072] The above porous support may be a so-called cross-linked porous support having a structure in which at least a portion of the polyethylene is cross-linked by a cross-linking compound. For example, the above cross-linked porous support may include a continuous phase matrix containing polyethylene and silane-modified polyethylene that is cross-linked within the continuous phase matrix and supports the continuous phase matrix. The above silane-modified polyethylene may mean that alkoxyvinylsilane is grafted into the polyethylene chain, and the alkoxyvinylsilane grafted into the polyethylene chain may react with moisture under predetermined conditions to cross-link the polyethylene chains. Since the above cross-linked porous support has a higher meltdown temperature compared to an uncross-linked porous support, the heat resistance of the electrolyte membrane can be significantly improved; however, since the tensile properties of the electrolyte membrane may deteriorate due to cross-linking, the content of the silane-modified polyolefin in the electrolyte membrane can be controlled to 0.1 to 50 weight%, preferably 0.1 to 30 weight%.

[0073] The porous support may further include an inorganic filler. The inorganic filler can compensate for and improve mechanical properties that deteriorate as the porosity of the porous support increases.

[0074] The above-mentioned inorganic filler may be, for example, one selected from the group consisting of silica (SiO2), TiO2, Al2O3, zeolite, AlOOH, BaTiO2, talc, Al(OH)3, CaCO3, and combinations of two or more of these, and preferably, may be spherical nanoparticles having an average particle size of 10 to 1,000 nm, more preferably, nanoparticles whose surface has been treated to be hydrophobic or hydrophilic. For example, silica (SiO2) may have a hydrocarbon layer formed on its surface consisting of hydrophobic linear hydrocarbon molecules. Since silica itself has hydrophilic properties, spherical silica nanoparticles coated with linear hydrocarbon molecules, for example (poly)ethylene, are suitable to improve compatibility with hydrophobic polyethylene.

[0075] The content of the inorganic filler in the porous support may be 10 to 70 weight percent, preferably 10 to 60 weight percent. If the content of the inorganic filler is less than 10 weight percent, the mechanical strength, acid resistance, chemical resistance, and flame retardancy of the porous support may be reduced, and if it exceeds 70 weight percent, the flexibility and processability of the porous support may be reduced.

[0076] The above electrolyte is a lithium salt solution, and the lithium salt solution may include a lithium salt and a glycol ether-based solvent having a boiling point of 110°C or higher.

[0077] The above lithium salt can improve ion conductivity and simultaneously serve to supply lithium ions. The above lithium salts are, for example, LiSCN, LiN(CN)2, LiClO4, LiBF4, LiAsF6, LiPF6, LiCF3SO3, LiCF3CO2, LiC(CF3SO2)3, LiSbF6, LiN(SO2CF3)2 (lithium bis(fluoromethanesulfonyl)imide; LiTFSI), LiN(FSO2)2 (lithium bis(fluorosulfonyl)imide; LiFSI), LiC4F9SO3, LiN(SO2CF2CF3)2, LiSbF6, LiPF3(CF2CF3)3, LiPF3(C2F5)3, LiPF3(CF3)3, LiCl, LiF, LiBr, LiI, LiB(C2O4)2, LiB 10 Cl 10 It may be one selected from the group consisting of LiFOB (lithium difluoro(oxalato)borate), LiBOB (lithium bis(oxalato)borate), and combinations of two or more of these, but is not limited thereto.

[0078] The glycol ether-based solvent mentioned above has a boiling point of 110°C or higher, preferably 200°C or higher, and may be, for example, one selected from the group consisting of diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, polyethylene glycol dimethyl ether, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, and combinations of two or more of these, and preferably, diethylene glycol monoethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, polyethylene glycol dimethyl ether, triethylene glycol monomethyl ether, polyethylene glycol monomethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, and combinations of two or more of these. It may be one selected from a group of combinations, but is not limited thereto.

[0079] If the boiling point of the glycol ether-based solvent is 110°C or higher, the phase of the electrolyte gelled by the polymer crosslinker can be stably maintained. Conversely, if the boiling point of the glycol ether-based solvent is less than 110°C, the solvent component in the gel electrolyte may evaporate arbitrarily, and the stability of the gel electrolyte may be significantly reduced.

[0080] In the above lithium salt solution, the molar ratio of the glycol ether-based solvent to the lithium salt may be 0.1:1 to 3:1, preferably 0.5:1 to 1.5:1.

[0081] If the molar ratio of the glycol ether-based solvent to the lithium salt is below or above the above range, the stability of the lithium salt solution may be reduced. Accordingly, within the above range, the lithium salt solution can improve ion conductivity by facilitating the movement of lithium ions more smoothly, and the stability and flame retardancy of the gel electrolyte can be improved due to the high boiling point of the glycol ether-based solvent.

[0082] The ionic conductivity of the above electrolyte membrane may be 0.3 mS / cm or higher, 0.4 mS / cm or higher, 0.5 mS / cm or higher, 0.6 mS / cm or higher, 0.7 mS / cm or higher, or 0.8 mS / cm or higher, and the pencil hardness of the gel electrolyte formed on at least one surface of the above porous support measured according to ASTM D3363 may be 3B or higher, 2B or higher, HB or higher, 2H or higher, 3H or higher, or 4H or higher.

[0083] Method for manufacturing an electrolyte membrane

[0084] FIG. 1 is a schematic representation of a method for manufacturing an electrolyte membrane according to one embodiment of the present invention. Referring to FIG. 1, a method for manufacturing an electrolyte membrane according to another aspect of the present invention may include: (a) a step of applying an electrolyte solution to one surface of a first release film to create a first electrolyte layer in a non-gelled state; (b) a step of laminating a porous support on the first electrolyte layer; (c) a step of applying an electrolyte solution to the porous support to create a second electrolyte layer in a non-gelled state; (d) a step of laminating a second release film on the second electrolyte layer, and then pressing the first and second release films to penetrate the first and second electrolyte layers into the pores of the porous support and integrate them; (e) a step of applying energy to the integrated first and second electrolyte layers to crosslink the first and second electrolyte layers; and (f) a step of removing the first and second release films.

[0085] In step (a) above, an electrolyte solution comprising a lithium salt solution, a polyfunctional monomer containing aromatic units, and an initiator may be applied to one side of the first release film (11) to create a first electrolyte layer (21). The first release film (11) may be a resin film through which energy applied in step (e) can pass, and the surface facing the first electrolyte layer (21) may be physically and / or chemically treated so that it can be easily peeled off in step (f).

[0086] In addition, the first release film (11) may have various physical properties depending on the type of energy applied in step (e). For example, if the energy is light, preferably UV, it may be able to transmit such UV, if the energy is heat, it may be able to sufficiently conduct such heat, and if the energy is a combination of light and heat, it may be able to transmit light and conduct heat at the same time.

[0087] The above electrolyte solution may include a lithium salt solution, a polyfunctional monomer containing aromatic units, and an initiator, and the effects, ratios, types, etc. of the lithium salt solution, the polyfunctional monomer containing aromatic units, and the initiator are as described above.

[0088] In step (b) above, a porous support (30) may be laminated on the first electrolyte layer (21). The porous support (30) is laminated on top of the first electrolyte layer (21) when the first electrolyte layer (21) is in a state where it is not gelled, that is, when it has a certain level of fluidity and flowability. At this time, some of the first electrolyte layer (21) may penetrate to a certain depth into the pores (31) located on the contact surface when in contact with the porous support (30) due to the capillary effect. The effects, materials, properties, specifications, etc. of the porous support (30) are as described above.

[0089] In step (c) above, a second electrolyte layer (22) can be formed by applying an electrolyte solution containing a lithium salt solution, a multifunctional monomer containing an aromatic unit, and an initiator onto the porous support (30). The electrolyte solution for forming the second electrolyte layer (22) may be the same as that used when forming the first electrolyte layer (21), and its components, effects, ratios, types, etc. are as described above. Since the second electrolyte layer (22) applied onto the porous support (30) is also in a non-gelled state, that is, has a certain level of fluidity and flowability, some of the second electrolyte layer (22) can penetrate to a certain depth into the pores (31) located on the contact surface when in contact with the porous support (30) due to the capillary effect.

[0090] In step (d) above, a second release film (12) is laminated onto the second electrolyte layer (22), and then the first and second release films (11, 12) are pressed to penetrate the first and second electrolyte layers (21, 22) into the pores (31) of the porous support (30) and integrate them.

[0091] Referring to FIG. 1, the first and second electrolyte layers (21, 22) applied to both sides of the porous support (30) in steps (a) to (c) can only penetrate to a certain depth into the pores (31) located on both sides of the porous support (30) by the capillary effect, and there is a problem that the first and second electrolyte layers (21, 22) cannot penetrate into the interior of the porous support (30), preferably into the pores located in the center, by this capillary effect alone.

[0092] That is, the electrolyte layer (21, 22) cannot be continuously formed from one side to the other side of the porous support (30) by penetration by the capillary effect alone, and in this case, the conductive path by the first and second electrolyte layers (21, 22) is blocked in at least a part of the electrolyte membrane, specifically in the center, so there is a problem that it is difficult to secure the required level of ion conductivity.

[0093] Accordingly, by pressing the first and second release films (11, 12) toward the center of the porous support (30) in step (d) above, the first and second electrolyte layers (21, 22) can be made to completely penetrate to the pore (31) located in the center of the porous support (30), and the first and second electrolyte layers (21, 22) can be integrated by coming into contact with each other at the pore (31) located in the center of the porous support (30).

[0094] The second release film (12) may also be a resin film through which energy applied in step (e) can pass, and the surface facing the second electrolyte layer (22) may be physically and / or chemically treated so that it can be easily peeled off in step (f).

[0095] In addition, the second release film (12) may have various physical properties depending on the type of energy applied in step (e). For example, if the energy is light, preferably UV, it may be able to transmit such UV, if the energy is heat, it may be able to sufficiently conduct such heat, and if the energy is a combination of light and heat, it may be able to transmit light and conduct heat at the same time.

[0096] In step (e) above, energy may be applied to the integrated first and second electrolyte layers to crosslink the polyfunctional monomer containing the aromatic unit. The energy may be one selected from the group consisting of heat, light, electron beams, and combinations of two or more of these, preferably heat or light, more preferably UV, but is not limited thereto. Through step (e), the polyfunctional monomer containing the aromatic unit dispersed in the electrolyte solution may be crosslinked to gel (harden) the integrated first and second electrolyte layers (21, 22).

[0097] In step (f) above, the first and second release films (11, 12) are removed to obtain an electrolyte membrane comprising: a porous support (30); and a gel electrolyte (20) filled in the pores (31) of the porous support (30) and formed on at least one surface of the porous support (30).

[0098] At this time, it is necessary to minimize damage to the surfaces of the first and second electrolyte layers (21, 22) as the first and second release films (11, 12) are peeled off. This is because when the release film is peeled off, if some of the electrolyte layers in contact with the release film are also peeled off, the effect of the gel electrolyte located on the surface of the porous support cannot be properly realized.

[0099] In this way, in order to selectively remove only the first and second release films (11, 12) without damaging the surfaces of the first and second electrolyte layers (21, 22), it is preferable to use the first and second release films (11, 12) having different thicknesses, and in step (f), to remove the thinner release film first and then remove the thicker release film later. The thickness of the first and second release films (11, 12) may each be 1 to 100 μm, preferably 10 to 100 μm, but is not limited thereto.

[0100] Within the above range, the thickness of the first release film (11) may be 25 to 100 μm, and the thickness of the second release film (12) may be 1 to 24 μm. At this time, by removing the second release film (12) in step (f) and then removing the first release film (11), a required level of smoothness can be secured without damaging the surfaces of the first and second electrolyte layers (21, 22).

[0101] Hereinafter, embodiments of the present invention will be described in detail.

[0102] Example 1

[0103] (1) Preparation of electrolyte solution

[0104] A LiFSl solution with a concentration of 1M was prepared by uniformly mixing 18.7g of Lithium bis(fluorosulfonyl)imide (LiFSl, Mw: 187.06g / mol, Cheonbo) with 100ml of TEGDME (Triethylene glycol dimethyl ether).

[0105] 80g of the above LiFSl solution, bisphenol A ethoxylate diacrylate (BPA(EO)) according to the above chemical formula 2, where m+n is 30 30An electrolyte solution was prepared by uniformly mixing 20g of DA and 1g of trimethylbenzoyl phenylphosphinate (TPO).

[0106] (2) Preparation of electrolyte membrane

[0107] The above electrolyte solution was applied to one side of a polyethylene terephthalate (PET) release film with a thickness of 50 μm, and then a polyethylene porous support (air permeability: 50 sec / 100 ml, thickness: 9.0 μm, porosity: 55 vol%) was laminated. The above electrolyte solution was applied onto the polyethylene porous support, and then a polyethylene terephthalate (PET) release film with a thickness of 23 μm was laminated. The release film and the polyethylene porous support were roll-pressed to obtain a structure in which the polyethylene porous support interposed between the release films was completely impregnated with the electrolyte solution.

[0108] An electrolyte membrane was manufactured by irradiating both sides of the above structure with 100W UV for 5 seconds to cure the electrolyte solution impregnated into the pores of the polyethylene porous support and applied to the surface, and then sequentially removing a release film with a thickness of 23㎛ and a release film with a thickness of 50㎛ laminated on both sides of the above structure.

[0109] Example 2

[0110] (1) Preparation of electrolyte solution

[0111] BPA(EO) 30 DA is bisphenol A ethoxylate diacrylate (BPA(EO)) according to the above chemical formula 2, where m+n is 20 20 An electrolyte solution was prepared in the same manner as in Example 1 above, except that it was replaced with DA.

[0112] (2) Preparation of electrolyte membrane

[0113] An electrolyte membrane was prepared using the same method as in Example 1 above.

[0114] Example 3

[0115] (1) Preparation of electrolyte solution

[0116] BPA(EO) 30 DA is bisphenol A ethoxylate diacrylate (BPA(EO)) according to the above chemical formula 2, where m+n is 10 10 An electrolyte solution was prepared in the same manner as in Example 1 above, except that it was replaced with DA.

[0117] (2) Preparation of electrolyte membrane

[0118] An electrolyte membrane was prepared using the same method as in Example 1 above.

[0119] Example 4

[0120] (1) Preparation of electrolyte solution

[0121] BPA(EO) 30 An electrolyte solution was prepared in the same manner as in Example 1, except that DA was replaced with bisphenol A ethoxylate diacrylate (BPA(EO)4DA) having m+n of 4 according to Chemical Formula 2 above.

[0122] (2) Preparation of electrolyte membrane

[0123] An electrolyte membrane was prepared using the same method as in Example 1 above.

[0124] Example 5

[0125] (1) Preparation of electrolyte solution

[0126] BPA(EO) 30 An electrolyte solution was prepared in the same manner as in Example 1, except that DA was replaced with bisphenol A ethoxylate diacrylate (BPA(EO)3DA) having m+n of 3 according to Chemical Formula 2 above.

[0127] (2) Preparation of electrolyte membrane

[0128] An electrolyte membrane was prepared using the same method as in Example 1 above.

[0129] Example 6

[0130] (1) Preparation of electrolyte solution

[0131] A LiFSl solution with a concentration of 1M was prepared by uniformly mixing 18.7g of Lithium bis(fluorosulfonyl)imide (LiFSl, Mw: 187.06g / mol, Cheonbo) with 100ml of TEGDME (Triethylene glycol dimethyl ether).

[0132] 80g of the above LiFSl solution, BPA(EO) 30 DA 10g, BPA(EO) 10 An electrolyte solution was prepared by uniformly mixing 10g of DA and 1g of trimethylbenzoyl phenylphosphinate (TPO).

[0133] (2) Preparation of electrolyte membrane

[0134] An electrolyte membrane was prepared using the same method as in Example 1 above.

[0135] Comparative Example 1

[0136] (1) Preparation of electrolyte solution

[0137] A LiFSl solution with a concentration of 1M was prepared by uniformly mixing 18.7g of Lithium bis(fluorosulfonyl)imide (LiFSl, Mw: 187.06g / mol, Cheonbo) with 100ml of TEGDME (Triethylene glycol dimethyl ether).

[0138] An electrolyte solution was prepared by uniformly mixing 80g of the above LiFSl solution, 20g of polyethylene glycol 400 diacrylate (PEG(400)DA), and 1g of trimethylbenzoyl phenylphosphinate (TPO).

[0139] (2) Preparation of electrolyte membrane

[0140] An electrolyte membrane was prepared using the same method as in Example 1 above.

[0141] Comparative Example 2

[0142] (1) Preparation of electrolyte solution

[0143] 92g of LiFSl solution prepared according to Example 1 above, BPA(EO) 30 An electrolyte solution was prepared by uniformly mixing 8g of DA and 1g of trimethylbenzoyl phenylphosphinate (TPO).

[0144] (2) Preparation of electrolyte membrane

[0145] An electrolyte membrane was prepared using the same method as in Example 1 above.

[0146] Comparative Example 3

[0147] (1) Preparation of electrolyte solution

[0148] 68g of LiFSl solution prepared according to Example 1 above, BPA(EO) 30 An electrolyte solution was prepared by uniformly mixing 32g of DA and 1g of trimethylbenzoyl phenylphosphinate (TPO).

[0149] (2) Preparation of electrolyte membrane

[0150] An electrolyte membrane was prepared using the same method as in Example 1 above.

[0151] The types and properties of the polyfunctional monomers used in the above examples and comparative examples are shown in Table 1 below.

[0152] Classification Type Ethylene Oxide (EO) Number of Repeating Units Glycerin Transition Temperature (°C) Example 1 BPA(EO)30DA30-57 Example 2 BPA(EO)20DA20-37 Example 3 BPA(EO)10DA10-7 Example 4 BPA(EO)4DA442 Example 5 BPA(EO)3DA367 Example 6 BPA(EO)30DA+BPA(EO)10DAN / DN / D Comparative Example 1 PEG400DA9-33 Comparative Example 2 BPA(EO)30DA30-57 Comparative Example 3 BPA(EO)30DA30-57

[0153]

[0154] Experimental Example

[0155] The physical properties of the electrolyte membranes prepared according to the above examples and comparative examples were measured and evaluated according to the following methods, and the results are shown in Table 2 below. Unless otherwise noted regarding temperature, measurements were taken at room temperature (25℃).

[0156] -Thickness (㎛): The thickness of the electrolyte membrane specimen was measured using a micro-thickness gauge.

[0157] - Impedance (mΩ), Ionic Conductivity (mS / cm): A coin cell was manufactured by inserting an electrolyte membrane prepared according to the above examples and comparative examples between 1mm thick SUS electrodes. The impedance and ionic conductivity of the electrolyte membrane inserted in the coin cell were measured using Electrochemical Impedance Spectroscopy (EIS) at a frequency of 10 4 ~10 6 The average value was calculated by taking 5 measurements under conditions of Hz, current 10.0mV, voltage range ±10V, and temperature 25℃.

[0158] - Pencil hardness: According to ASTM D3363, a 6B to 6H pencil was brought into contact with the surface of the electrolyte membrane specimen at a 45° angle, and the hardness was measured by determining whether scratches occurred on the surface of the electrolyte membrane specimen by pushing the pencil with a load of 100g at a speed of 30mm / min. After measurement, the surface of the electrolyte membrane specimen was observed under an optical microscope (200x magnification).

[0159] Classification Thickness Impedance Ionic Conductivity Pencil Hardness Example 1 107 5.4 0.8 6 15H Example 2 101 13.1 0.6 3 3H Example 3 101 32.4 0.4 9 1 2H Example 4 101 62.5 0.4 0 5HB Example 5 101 78.8 0.3 6 9HB Example 6 101 05.6 0.7 1 5 4H Comparative Example 1 109 8.7 0.6 5 8 5B Comparative Example 2 109 1.3 0.6 4 6B Comparative Example 3 101 24.8 0.5 1 8 4B

[0160]

[0161] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical spirit or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single unit may be implemented in a distributed manner, and components described as distributed may likewise be implemented in a combined form.

[0162] The scope of the present invention is defined by the claims set forth below, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention.

[0163] <Explanation of Symbols>

[0164] 11: First release film

[0165] 12: Second release film

[0166] 20: Gel electrolyte

[0167] 21: First electrolyte layer

[0168] 22: Second electrolyte layer

[0169] 30: Porous support

[0170] 31: Qi Gong

Claims

1. Porous support; and A gel electrolyte filled into the pores of the porous support and formed on at least one surface of the porous support; comprising The gel electrolyte comprises a matrix containing an electrolyte and a crosslinker that is crosslinked within the matrix and supports the matrix, and The above crosslinker is produced by the crosslinking reaction of a polyfunctional monomer containing aromatic units, Electrolyte membrane.

2. In Paragraph 1, The above-mentioned polyfunctional monomer has a structure according to the following chemical formula 1, Electrolyte membrane: <Chemical Formula 1> In the above chemical formula 1, Ar is an aromatic unit, and R1 and R2 are each an acrylate group, a methacrylate group, a vinyl group, or an allyl group containing a crosslinkable double bond, and AO1 and AO2 are each alkylene oxide groups, and m and n are integers greater than or equal to 0, and m+n is greater than or equal to 1.

3. In Paragraph 2, The above aromatic unit has a bisphenol A structure, Electrolyte membrane.

4. In Paragraph 1, The content of the crosslinker in the above gel electrolyte is 10 to 30 weight percent, Electrolyte membrane.

5. In Paragraph 1, The above porous support comprises one selected from the group consisting of polyethylene, polypropylene, polybutylene, polymenylpentene, ethylene vinyl acetate, ethylene butyl acrylate, ethylene ethyl acrylate, and combinations or copolymers of two or more of these. Electrolyte membrane.

6. In Paragraph 5, The above porous support further comprises an inorganic filler, Electrolyte membrane.

7. In Paragraph 1, The porosity of the above porous support is 30–90%, the average pore size is 20–100 nm, and the thickness is 1–20 µm, and The filling rate of the gel electrolyte into the pores of the porous support is 90% or more, Electrolyte membrane.

8. In Paragraph 1, The thickness of the gel electrolyte formed on at least one surface of the porous support is 0.1 to 50 μm, Electrolyte membrane.

9. In Paragraph 1, The above electrolyte is a lithium salt solution, and The above lithium salt solution comprises a lithium salt and a glycol ether-based solvent having a boiling point of 110°C or higher, Electrolyte membrane.

10. In Paragraph 1, The ionic conductivity of the above electrolyte membrane is 0.3 mS / cm or higher, and The gel electrolyte formed on at least one surface of the porous support having a pencil hardness of 3B or higher as measured according to ASTM D3363 Electrolyte membrane.

11. A method for manufacturing an electrolyte membrane according to any one of claims 1 to 10, (a) a step of applying an electrolyte solution to one side of a first release film to create a first electrolyte layer in a non-gelled state; (b) a step of laminating a porous support on the first electrolyte layer; (c) a step of applying an electrolyte solution onto the porous support to produce a second electrolyte layer in a non-gelled state; (d) a step of laminating a second release film on the second electrolyte layer, and then pressing the first and second release films to penetrate the first and second electrolyte layers into the pores of the porous support and integrate them; (e) a step of applying energy to the integrated first and second electrolyte layers to crosslink the first and second electrolyte layers; and (f) a step of removing the first and second release films; comprising, Method for manufacturing an electrolyte membrane.

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