Solid-liquid hybrid electrolyte membranes for lithium secondary batteries

Abstract

The present specification relates to a solid-liquid hybrid electrolyte membrane for a lithium secondary battery.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0155865 dated November 12, 2021, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a solid-liquid hybrid electrolyte membrane for a lithium secondary battery. [Background technology]

[0003] Lithium secondary batteries are becoming increasingly important due to the increasing use of vehicles, computers, and portable devices. Among these, there is a particular demand for lightweight lithium secondary batteries that can achieve high energy density. Such lithium secondary batteries consist of a separator between the positive and negative electrodes, followed by a liquid or solid electrolyte.

[0004] Lithium-ion secondary batteries using liquid electrolytes have a structure in which a separator separates the negative and positive electrodes, so if the separator is damaged by deformation or external impact, a short circuit may occur, which can lead to leakage and evaporation, or the risk of overheating or explosion. Therefore, there is a need to improve the safety of lithium-ion secondary batteries that use existing liquid electrolytes.

[0005] In addition, all-solid-state batteries that use solid electrolytes can increase battery stability and prevent electrolyte leakage, improving battery reliability. However, solid electrolytes have very low ionic conductivity at room temperature, which can reduce battery performance. Therefore, even when using solid electrolytes, there is still a need to develop solid electrolyte membranes that have high energy density and improved processability.

[0006] Therefore, it is necessary to secure a technology for a lithium ion secondary battery that uses a solid-liquid hybrid or solid electrolyte without leakage instead of the existing liquid electrolyte for ion transfer. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Korean Patent Publication No. 2003-0097009 (2003.12.31), "Polymer electrolyte with excellent leak resistance and lithium battery using the same" Summary of the Invention [Problem to be solved by the invention]

[0008] One aspect of the present invention is to solve the above-mentioned technical problems by providing a solid-liquid hybrid electrolyte membrane for a lithium secondary battery, which does not leak or volatilize in normal pressure and high pressure environments, has excellent mechanical strength, and has high ionic conductivity, and provides a lithium secondary battery having improved performance including the same.

[0009] Other objects and advantages of the present invention will be apparent from the following description, and it will be readily apparent that the objects and advantages of the present invention can be realized by the means or methods described in the claims and their combinations. [Means for solving the problem]

[0010] One aspect of the present invention provides a solid-liquid hybrid electrolyte membrane comprising a polymer; a liquid-phase polyhedral oligomeric silsesquioxane (POSS) represented by the following Chemical Formula 1; and a lithium salt:

[0011] [ka]

[0012] In the above Chemical Formula 1, R are the same or different and are each independently selected from the group consisting of groups represented by the following chemical formulas 1-1 to 1-4:

[0013] [ka]

[0014] In the above Chemical Formulas 1-1 to 1-4, L1 to L5 are C1 to C30 alkylene groups, R1 to R4 are selected from the group consisting of hydrogen; a hydroxy group; an amino group; a thiol group; a C1 to C30 alkyl group; a C2 to C30 alkenyl group; a C2 to C30 alkynyl group; a C1 to C30 alkoxy group; and a C1 to C30 carboxyl group; m and n are the same or different and each independently represents an integer from 0 to 10; * indicates the binding position.

[0015] In one embodiment of the present invention, in the above formulas 1-1 to 1-4, L1 to L5 are C1 to C10 alkylene groups, R1 to R4 are hydrogen; a hydroxy group; or a C1 to C30 alkyl group, and m and n are the same or different and each independently represent an integer of 0 to 10.

[0016] In one embodiment of the present invention, R in Formula 1 is selected from the group consisting of a polyethylene glycol group, a glycidyl group, an octasilane group, and a methacryl group.

[0017] In one embodiment of the present invention, the polymer is selected from the group consisting of polypropylene carbonate (PPC), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), and polyvinylpyrrolidone (PVP) in the main chain or side chain.

[0018] In one embodiment of the present invention, the lithium salt includes one or more selected from the group consisting of LiPF6, LiBF4, LiSbF6, LiAsF6, LiOH, LiOH·H2O, LiBOB, LiClO4, LiN(C2F5SO2)2, CF3SO3Li, LiC(CF3SO2)3, LiC4BO8, LiTFSI, LiFSI, LiClO4, and combinations thereof.

[0019] In one embodiment of the present invention, the content ratio of the polymer and the liquid-phase cage silsesquioxane is 1:1 to 1:8.

[0020] In one embodiment of the present invention, the content ratio of the liquid-phase cage silsesquioxane and the lithium salt is 10:1 to 1:5.

[0021] In one embodiment of the present invention, the ionic conductivity of the electrolyte membrane is 1.0×10 ‐7 or 9.0 x 10 ‐5 S / cm.

[0022] In one embodiment of the present invention, the electrolyte membrane has a thickness of 1 to 200 μm.

[0023] Another aspect of the present invention provides a lithium secondary battery comprising: a positive electrode; a negative electrode; and a solid-liquid hybrid electrolyte membrane according to the present invention. [Effects of the Invention]

[0024] A solid-liquid hybrid electrolyte membrane for a lithium secondary battery according to one aspect of the present invention does not leak or volatilize even under normal pressure or under applied pressure, has high ionic conductivity, and is excellent in stability and mechanical strength.

[0025] Furthermore, the lithium secondary battery including the solid-liquid hybrid electrolyte membrane for lithium secondary batteries has excellent charge / discharge characteristics and life characteristics. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a schematic diagram of a solid-liquid hybrid electrolyte membrane according to one aspect of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] While the present invention may be embodied in several different forms, it is to be understood that the invention is not limited to the disclosed embodiments, and the accompanying drawings may serve to better illustrate, explain, and explain the principles of the present invention.

[0028] The terms and words used in this specification and claims should not be interpreted in a limited manner based on their ordinary or dictionary meanings, but should be interpreted in a manner that is consistent with the technical idea of the present invention, in accordance with the principle that the inventor can appropriately define the concept of the term in order to best explain his / her invention.

[0029] The terms used in the present invention are merely used to describe specific embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present invention, terms such as "comprise" or "have" specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the presence or additional possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0030] The present invention relates to a solid-liquid hybrid electrolyte membrane, a method for producing the same, and a lithium secondary battery including the same.

[0031] A solid-liquid hybrid electrolyte membrane according to one aspect of the present invention comprises a solid-phase polymer and a liquid-phase polyhedral oligomeric silsesquioxane (POSS). The solid-liquid hybrid electrolyte membrane contains a liquid phase and is in the form of a solid phase, and does not leak or volatilize under normal pressure or under applied pressure.

[0032] Such a solid-liquid hybrid electrolyte membrane contains a predetermined amount of liquid-phase cage silsesquioxane within the solid-phase polymer chain structure, and the liquid-phase cage silsesquioxane may be impregnated within the solid-phase polymer chain structure, or the liquid-phase cage silsesquioxane may be coated on the portion or surface of the solid-phase polymer that comes into contact with the solid-phase polymer.

[0033] The solid-liquid hybrid electrolyte membrane according to the present invention includes a solid-phase polymer with low ionic conductivity and an appropriate content of a liquid-phase cage-type silsesquioxane, thereby ensuring improved ionic conductivity compared to conventional solid electrolyte membranes and simultaneously providing mechanical strength sufficient for freestanding.

[0034] 1 is a schematic diagram showing the structure of a solid-liquid hybrid electrolyte membrane according to one aspect of the present invention. The present invention will be described in more detail below with reference to the drawings.

[0035] Referring to FIG. 1, a solid-liquid hybrid electrolyte membrane 10 according to one aspect of the present invention comprises a solid-phase polymer 1 and a predetermined amount of a liquid-phase cage-type silsesquioxane 2 .

[0036] The solid-phase polymer 1 is a polymer that is solid at room temperature and has low solubility in the electrolyte solution.

[0037] The liquid-phase cage-type silsesquioxane 2 is liquid at room temperature. When the liquid-phase cage-type silsesquioxane is thermally cured, it may undergo polymerization and turn into a solid. According to the present invention, a solid-liquid hybrid electrolyte membrane can be prepared by mixing a solid-phase polymer and a liquid-phase cage-type silsesquioxane in a specific ratio. A more detailed description is provided below.

[0038] A solid-liquid hybrid electrolyte membrane according to one aspect of the present invention can include a polymer; a liquid-phase polyhedral oligomeric silsesquioxane (POSS) represented by the following Chemical Formula 1; and a lithium salt:

[0039] [ka]

[0040] In the above Chemical Formula 1, R are the same or different and are each independently selected from the group consisting of groups represented by the following chemical formulas 1-1 to 1-4: [ka]

[0041] In the above Chemical Formulas 1-1 to 1-4, L1 to L5 are C1 to C30 alkylene groups, R1 to R4 are selected from the group consisting of hydrogen; a hydroxy group; an amino group; a thiol group; a C1 to C30 alkyl group; a C2 to C30 alkenyl group; a C2 to C30 alkynyl group; a C1 to C30 alkoxy group; and a C1 to C30 carboxyl group; m and n are the same or different and each independently represents an integer from 0 to 10; * indicates the binding position.

[0042] Polyhedral oligomeric silsesquioxanes (POSS) have a variety of structures, including random, ladder, cage, and partial cage structures. Among these, the polyhedral silsesquioxanes contained in the solid-liquid hybrid electrolyte membrane according to the present invention have a silica cage structure with a diameter of approximately 1 to 5 nm depending on the cage size. They are organic-inorganic composites that possess the properties of both inorganic silica (SiO2) and organic silicone (R2SiO). The polyhedral silsesquioxanes reduce void spaces in the electrolyte, forming a more rigid and dense structure, thereby improving mechanical properties and strength.

[0043] The present inventors have found that ionic conductivity can be improved by mixing a solid-phase polymer having low ionic conductivity with a liquid-phase cage silsesquioxane represented by the following chemical formula 1. By mixing the solid-phase polymer of the present invention with a liquid-phase cage silsesquioxane, the cage silsesquioxane is positioned between the polymer chains, facilitating the movement of the polymer chains and thereby facilitating the mobility of lithium ions, thereby improving ionic conductivity. The liquid-phase cage silsesquioxane represented by the following chemical formula 1 is as follows:

[0044] [ka]

[0045] In the above Chemical Formula 1, R are the same or different and are each independently selected from the group consisting of groups represented by the following chemical formulas 1-1 to 1-4:

[0046] [ka]

[0047] In the above Chemical Formulas 1-1 to 1-4, L1 to L5 are C1 to C30 alkylene groups, R1 to R4 are selected from the group consisting of hydrogen; a hydroxy group; an amino group; a thiol group; a C1 to C30 alkyl group; a C2 to C30 alkenyl group; a C2 to C30 alkynyl group; a C1 to C30 alkoxy group; and a C1 to C30 carboxyl group; m and n are the same or different and each independently represents an integer from 0 to 10; * indicates the binding position.

[0048] In Formula 1, R may have one or more functional groups capable of bonding with a lithium ion.

[0049] In one embodiment of the present invention, R may be a group represented by Chemical Formula 1-1, where L1 and L2 may be a C1 to C30 alkylene group, preferably a C1 to C20 alkylene group, and more preferably a C1 to C10 alkylene group. In Chemical Formula 1-1, R1 may be hydrogen, a C1 to C30 alkyl group, a C2 to C30 alkenyl group, a C2 to C30 alkynyl group, a C1 to C30 alkoxy group, or a C1 to C30 carboxyl group, preferably a C1 to C20 alkyl group, a C2 to C20 alkenyl group, a C2 to C20 alkynyl group, a C1 to C20 alkoxy group, or a C1 to C20 carboxyl group, and more preferably a C1 to C10 alkyl group, a C2 to C10 alkenyl group, a C2 to C10 alkynyl group, a C1 to C10 alkoxy group, or a C1 to C10 carboxyl group.

[0050] In another embodiment of the present invention, R may be a group represented by Chemical Formula 1-2, where L3 and L4 may be a C1 to C30 alkylene group, preferably a C1 to C20 alkylene group, and more preferably a C1 to C10 alkylene group.

[0051] In another embodiment of the present invention, R may be a group represented by Chemical Formula 1-3, wherein R2 to R4 are the same or different and each independently represent a hydrogen atom, a hydroxyl group, a C1 to C30 alkyl group, a C2 to C30 alkenyl group, a C2 to C30 alkynyl group, or a C1 to C30 alkoxy group, preferably a hydrogen atom, a hydroxyl group, a C1 to C20 alkyl group, a C2 to C20 alkenyl group, a C2 to C20 alkynyl group, or a C1 to C20 alkoxy group, more preferably a hydrogen atom, a hydroxyl group, a C1 to C10 alkyl group, a C2 to C10 alkenyl group, a C2 to C10 alkynyl group, or a C1 to C10 alkoxy group.

[0052] In another embodiment of the present invention, R may be a group represented by Chemical Formula 1-4, where L5 may be a C1 to C30 alkylene group, preferably a C1 to C20 alkylene group, and more preferably a C1 to C10 alkylene group.

[0053] For example, in Formula 1, R may be selected from the group consisting of a polyethylene glycol group, a glycidyl group, an octasilane group, and a methacryl group, and R may be [ka] (wherein m is an integer from 1 to 9), [ka] , [ka] , [ka] (where * indicates a binding position), but is not limited thereto.

[0054] In one embodiment of the present invention, the polymer may be a polymer that does not undergo phase separation when mixed with the liquid-phase cage silsesquioxane, or may be a solid-phase polymer that can be fused with the liquid-phase cage silsesquioxane when mixed in an appropriate ratio, i.e., has compatibility with liquid-phase POSS.

[0055] Specifically, the polymer may be selected from the group consisting of polypropylene carbonate (PPC), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), and polyvinylpyrrolidone (PVP) in the main chain or side chain.

[0056] In one embodiment of the present invention, the solid-liquid hybrid electrolyte membrane comprising the polymer and the liquid-phase cage silsesquioxane represented by Formula 1 may further comprise a lithium salt.

[0057] The lithium salt acts as a lithium ion source within the battery, enabling basic lithium secondary battery operation and promoting the movement of lithium ions between the positive electrode and the negative electrode. The lithium salt may be, but is not limited to, one selected from the group consisting of LiPF6, LiBF4, LiSbF6, LiAsF6, LiOH, LiOH·H2O, LiBOB, LiClO4, LiN(C2F5SO2)2, LiN(CF3SO2)2, CF3SO3Li, LiC(CF3SO2)3, LiC4BO8, LiFSI, LiClO4, and combinations thereof.

[0058] The content of the lithium salt may be 10 to 50 parts by weight, preferably 15 to 45 parts by weight, and more preferably 20 to 40 parts by weight, based on 100 parts by weight of the total electrolyte membrane. If the content is less than 10 parts by weight, the ionic conductivity of the electrolyte membrane may be reduced due to the low content. If the content is 50 parts by weight or more, not all of the lithium salt may be dissociated within the electrolyte membrane and exist in a crystalline state, which may not contribute to ionic conductivity but may hinder ionic conductivity and reduce ionic conductivity. Furthermore, the polymer content may be relatively reduced, which may weaken the mechanical strength of the solid-liquid hybrid electrolyte membrane. Therefore, the content should be appropriately controlled within the above range.

[0059] In one embodiment of the present invention, the ratio of the polymer to the liquid-phase cage silsesquioxane may be 1:1 to 1:8, preferably 1:1 to 1:6, and more preferably 1:1 to 1:4. If the ratio of the polymer to the liquid-phase cage silsesquioxane exceeds 1:1 to 1:8, the polymer may not exist in a solid phase, resulting in leakage.

[0060] In one embodiment of the present invention, the content ratio of the liquid-phase cage-type silsesquioxane to the lithium salt may be 10:1 to 1:5, preferably 10:1 to 1:1, and more preferably 10:1 to 2:1. If the content ratio of the liquid-phase cage-type silsesquioxane to the lithium salt is less than 10:1 to 1:5, the amount of lithium ions is small, resulting in reduced ionic conductivity. If the content ratio exceeds 10:1 to 1:5, the amount of lithium ions is too large to be dissociated, resulting in precipitation or increased viscosity, resulting in reduced ionic conductivity.

[0061] In one embodiment of the present invention, the ionic conductivity of the solid-liquid hybrid electrolyte membrane is 1.0×10 ‐7 or 9.0 x 10 ‐5 S / cm, preferably 1.1×10 ‐7 or 8.9 x 10 ‐7 It may be S / cm.

[0062] In one embodiment of the present invention, the electrical resistivity of the solid-liquid hybrid electrolyte membrane may be 10.0 to 60,000 ohms (Ω), preferably 50.0 to 55,000 ohms (Ω).

[0063] In the solid-liquid hybrid electrolyte membrane, as the content of the liquid-phase cage silsesquioxane relative to the polymer increases, the electrical resistance of the electrolyte membrane may increase, and the ionic conductivity of the electrolyte membrane may also increase.

[0064] In one embodiment of the present invention, the thickness of the solid-liquid hybrid electrolyte membrane may be 1 to 200 μm, preferably 5 to 195 μm. If the thickness of the solid-liquid hybrid electrolyte membrane is less than 1 μm, the mechanical strength of the electrolyte membrane may be weak, making it difficult to assemble the battery or causing an electrical short circuit. Furthermore, if the thickness of the solid-liquid hybrid electrolyte membrane is more than 200 μm, the energy density and ionic conductivity may be low, making it difficult to apply to a battery.

[0065] In one embodiment of the present invention, a lithium secondary battery includes a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and the separator may include the solid-liquid hybrid electrolyte membrane according to the present invention.

[0066] The positive and negative electrodes each include a current collector and an electrode active material layer formed on at least one surface of the current collector, the active material layer including a plurality of electrode active material particles and a solid electrolyte. The electrodes may further include one or more of a conductive material and a binder resin, as needed. The electrodes may also include various additives to complement or improve the physicochemical properties of the electrodes.

[0067] In the present invention, the negative electrode active material may be any material that can be used as a negative electrode active material for a lithium ion secondary battery. For example, the negative electrode active material may be carbon such as non-graphitizable carbon or graphite-based carbon; Li xFe2O3 (0 ≦ x ≦ 1), Li x WO2 (0 ≦ x ≦ 1), Sn x Me 1‐x Me’ y O z (Me is Mn, Fe, Pb, and Ge; Me’ is Al, B, P, Si, Group 1, Group 2, Group 3 elements in the periodic table, and halogen; 0 < x ≦ 1; 1 ≦ y ≦ 3; 1 ≦ z ≦ 8) such metal composite oxides; lithium metal; lithium alloy; silicon-based alloy; tin-based alloy; metal oxides such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, and Bi2O5; conductive polymers such as polyacetylene; Li-Co-Ni-based materials; titanium oxides; lithium titanium oxides, etc. One or more selected from these can be used. In a specific embodiment, the negative electrode active material can contain a carbon-based material and / or Si.

[0068] In the case of the positive electrode, the electrode active material can be used without limitation as long as it can be used as the positive electrode active material of a lithium ion secondary battery. For example, the positive electrode active material is a layered compound such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; the chemical formula Li 1+x Mn 2‐x O4 (where x is 0 to 0.33), lithium manganese oxides such as LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiFe3O4, V2O5, Cu2V2O7; the chemical formula LiNi 1‐x M x O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x = 0.01 to 0.3) Ni-site type lithium nickel oxide represented by; the chemical formula LiMn 2‐x M x O2 (where M = Co, Ni, Fe, Cr, Zn or Ta, and x = 0.01 to 0.1) or lithium manganese composite oxide represented by Li2Mn3MO8 (where M = Fe, Co, Ni, Cu or Zn); LiNi xMn 2‐x Examples of the lithium manganese composite oxide include, but are not limited to, lithium manganese composite oxides with a spinel structure represented by O4, LiMn2O4 in which part of the Li in the chemical formula is replaced with an alkaline earth metal ion, disulfide compounds, and Fe2(MoO4)3.

[0069] In the present invention, the current collector is an electrically conductive material such as a metal plate, and can be selected from appropriate ones according to the polarity of the current collector electrode as known in the field of secondary batteries.

[0070] In the present invention, the conductive material is used to provide conductivity to the electrode and is typically added in an amount of 1 to 30 wt % based on the total weight of the mixture including the electrode active material. The conductive material is not particularly limited as long as it is conductive without causing chemical changes in the battery, and may include, for example, one or a mixture of two or more conductive materials selected from the following: graphite (e.g., natural graphite, artificial graphite, etc.), carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, etc.; conductive fibers (e.g., carbon fiber, metal fiber, etc.); metal powders (e.g., carbon fluoride, aluminum, nickel powder, etc.); conductive whiskers (e.g., zinc oxide, potassium titanate, etc.); conductive metal oxides (e.g., titanium oxide, etc.); polyphenylene derivatives, etc.

[0071] In the present invention, the binder resin serves to firmly adhere negative electrode active material particles to each other and to firmly adhere the negative electrode active material to the current collector, and is not particularly limited as long as it is a component that aids in bonding the active material to the conductive material and the current collector, and examples thereof include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluororubber, various copolymers, etc. The binder resin may typically be included in an amount of 1 to 30 wt %, or 1 to 10 wt %, based on 100 wt % of the electrode layer.

[0072] Meanwhile, in the present invention, the electrode active material layer may contain one or more additives such as an oxidation stabilizing additive, a reduction stabilizing additive, a flame retardant, a heat stabilizer, an antifogging agent, etc., if necessary.

[0073] The present invention will be described in more detail with reference to the following examples. However, the following examples are for illustrative purposes only and the scope of the present invention is not limited to these examples.

[0074] Example [Example 1] Solution A was prepared by adding 10 wt% of the polymer polyvinylidene fluoride (PVDF) (Sigma-Aldrich) to N-methyl-2-pyrrolidone (NMP) and thoroughly stirring at 60°C.

[0075] Solution B was prepared by thoroughly stirring polyethylene glycol-polyhedralic oligomeric silsesquioxane (PEG-POSS) (Hybridplastics) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) (Sigma-Aldrich) in a weight ratio of 10:4 at 60°C.

[0076] The solutions A and B were thoroughly stirred at room temperature for 24 hours so that the content ratio of PVDF:PEG-POSS-LiTFSI became 1:2.

[0077] The prepared solution was coated on a stainless steel foil using a doctor blade and then vacuum dried at 100° C. for 12 hours to prepare a solid electrolyte membrane.

[0078] [Example 2] A solid electrolyte membrane was prepared in the same manner as in Example 1, except that the content ratio of PVDF:PEG-POSS-LiTFSI was 1:3.

[0079] [Example 3] A solid electrolyte membrane was prepared in the same manner as in Example 1, except that the content ratio of PVDF:PEG-POSS-LiTFSI was 1:4.

[0080] [Example 4] A solid electrolyte membrane was prepared in the same manner as in Example 1, except that polypropylene carbonate (PPC) was used instead of PVDF.

[0081] [Example 5] A solid electrolyte membrane was prepared in the same manner as in Example 1, except that polyacrylonitrile (PAN) was used instead of PVDF and the content ratio of PAN:PEG-POSS-LiTFSI was 1:1.

[0082] [Example 6] A solid electrolyte membrane was prepared in the same manner as in Example 1, except that polyacetonitrile (PAN) was used instead of PVDF and the content ratio of PAN:PEG-POSS-LiTFSI was 1:2.

[0083] [Example 7] A solid electrolyte membrane was prepared in the same manner as in Example 1, except that polyvinylpyrrolidone (PVP) was used instead of PVDF and the content ratio of PVP:PEG-POSS-LiTFSI was 1:1.

[0084] [Example 8] A solid electrolyte membrane was prepared in the same manner as in Example 1, except that polyvinylpyrrolidone (PVP) was used instead of PVDF.

[0085] [Example 9] A solid electrolyte membrane was prepared in the same manner as in Example 2, except that Glycidyl-POSS-LiTFSI was used instead of PEG-POSS-LiTFSI.

[0086] [Example 10] A solid electrolyte membrane was prepared in the same manner as in Example 2, except that Octasilane-POSS-LiTFSI was used instead of PEG-POSS-LiTFSI.

[0087] [Comparative Example 1] A solution was prepared by adding 10 wt% of a polymer, polyvinylidene fluoride (PVDF) (Sigma-Aldrich), to N-methyl-2-pyrrolidone (NMP) and thoroughly stirring at 60°C.

[0088] The solution was thoroughly stirred at room temperature for 24 hours so that the PVDF:LiTFSI content ratio became 10:2.

[0089] The prepared solution was coated on a stainless steel foil using a doctor blade and then vacuum dried at 100° C. for 12 hours to prepare a solid electrolyte membrane.

[0090] Comparative Example 2 A solid electrolyte membrane was prepared in the same manner as in Comparative Example 1, except that polypropylene carbonate (PPC) was used instead of PVDF and the content ratio of PPC:LiTFSI was 10:3.

[0091] Comparative Example 3 A solid electrolyte membrane was prepared in the same manner as in Comparative Example 1, except that PAN was used instead of PVDF and the content ratio of PAN:LiTFSI was 10:5.

[0092] Comparative Example 4 A solid electrolyte membrane was prepared in the same manner as in Comparative Example 1, except that polyvinylpyrrolidone (PVP) was used instead of PVDF.

[0093] Comparative Example 5 A solid electrolyte membrane was prepared in the same manner as in Comparative Example 1, except that PEG-POSS-LiTFSI was used instead of LiTFSI and the content ratio of PVDF:PEG-POSS-LiTFSI was 1:6.

[0094] Experimental Example 1: Ionic conductivity of solid-liquid hybrid electrolyte membranes at ambient pressure Using an analyzer VMP3 (Biologic science instrument), electrochemical impedance was measured at 23°C, an amplitude of 10 mV, and a scan range of 500 KHz to 20 MHz, and based on this, ionic conductivity was calculated using the following equation 1.

[0095]

number

[0096] In the above formula 1, σ represents ionic conductivity, l represents the thickness of the membrane, R represents resistance, and a represents area.

[0097] The ionic conductivities calculated using the above formula 1 are shown in Table 1 below.

[0098] [Table 1]

[0099] As can be seen from Table 1, according to the present invention, the ionic conductivity of the electrolyte membrane containing the polymer and POSS in a specific content ratio was improved. On the other hand, it was found that the ionic conductivity was low in the case of an electrolyte membrane not containing the polymer and POSS, which have low ionic conductivity.

[0100] Experimental Example 2: Weight change of solid-liquid hybrid electrolyte membrane under high pressure To evaluate the leakage characteristics of the electrolyte membrane, the prepared electrolyte membrane was punched out to a diameter of 1.9 cm, a separator was placed on one side, and the membrane was placed in a jig and pressurized at 1 MPa for 1 minute. The weights before and after pressurization were measured, and the weight change was calculated using the following equation 2.

[0101] [Formula 2] Weight change (%) = {(weight before pressure - weight after pressure) / weight before pressure} * 100

[0102] The weight change is shown in Table 2 below.

[0103] [Table 2]

[0104] As shown in Table 2, the weight change of the solid-liquid hybrid electrolyte membrane according to the present invention was 0.2% or less, and it was confirmed that the electrolyte membrane hardly leaked. On the other hand, in Comparative Example 5, when an excessive amount of POSS was contained, the weight change of the electrolyte membrane was 5.2%, which was large, and it was found that this did not have the form of a solid electrolyte membrane and that the electrolyte membrane leaked when pressure was applied. [Explanation of symbols]

[0105] 10: Solid-liquid hybrid electrolyte membrane 1: Polymers in the solid phase 2: Liquid-phase cage-type silsesquioxane

Claims

1. A polymer comprising: a liquid-phase polyhedral oligomeric silsesquioxane (POSS) represented by the following chemical formula 1; and a lithium salt; The polymer is selected from the group consisting of polypropylene carbonate (PPC), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), and polyvinylpyrrolidone (PVP) in the main chain or side chain, solid-liquid hybrid electrolyte membrane: 【Chemical 1】 In the above Chemical Formula 1, R are the same or different and are each independently selected from the group consisting of groups represented by the following formulas 1-2 to 1-4: 【Chemistry 2】 In the above Chemical Formulas 1-2 to 1-4, L3 to L5 are C1 to C30 alkylene groups; R2 to R4 are selected from the group consisting of hydrogen; a hydroxy group; an amino group; a thiol group; a C1 to C30 alkyl group; a C2 to C30 alkenyl group; a C2 to C30 alkynyl group; a C1 to C30 alkoxy group; and a C1 to C30 carboxyl group; * indicates the bond position.

2. In the above Chemical Formulas 1-2 to 1-4, L1 to L5 are C1 to C10 alkylene groups; R1 to R4 are hydrogen; a hydroxy group; or a C1 to C30 alkyl group; 2. The solid-liquid hybrid electrolyte membrane according to claim 1, wherein m and n are the same or different and each independently represents an integer of 0 to 10.

3. 2. The solid-liquid hybrid electrolyte membrane according to claim 1, wherein R is selected from the group consisting of a glycidyl group, a dimethylsilyloxy group, and a methacryl group.

4. The lithium salt is LiPF ６ , LiBF ４ , LiSbF ６ , LiAsF ６ , LiOH, LiOH・H ２ O, LiBOB, LiClO ４ , LiN(C ２ F ５ SO ２ ) ２ , LiN(CF ３ SO ２ ) ２ , C.F. ３ SO ３ Li, LiC(CF ３ SO ２ ) ３ , LiC ４ BO ８ , LiFSI, LiClO ４ 10. The solid-liquid hybrid electrolyte membrane of claim 1, comprising one or more selected from the group consisting of:

5. 2. The solid-liquid hybrid electrolyte membrane according to claim 1, wherein the content ratio of the polymer to the sum of the liquid-phase cage silsesquioxane and the lithium salt is 1:1 to 1:

8.

6. 2. The solid-liquid hybrid electrolyte membrane according to claim 1, wherein the content ratio of the liquid-phase cage-type silsesquioxane to the lithium salt is 10:1 to 1:

5.

7. The ionic conductivity of the electrolyte membrane is 1.0×10 based on 25° C. ‐７ or 9.0 x 10 ‐５ 2. The solid-liquid hybrid electrolyte membrane according to claim 1, wherein the electrolytic capacitance is 100 Å / cm.

8. 2. The solid-liquid hybrid electrolyte membrane according to claim 1, wherein the thickness of the electrolyte membrane is 1 μm to 200 μm.

9. Positive electrode; a negative electrode; and A lithium secondary battery comprising the solid-liquid hybrid electrolyte membrane according to any one of claims 1 to 8.

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