Polymer electrolyte and lithium secondary battery comprising same

Abstract

Disclosed is a polymer electrolyte, the polymer electrolyte comprising: a crosslinked polymer comprising repeating units (A) derived from a crosslinkable monomer including an acrylate-based functional group; and an organic solvent containing a compound expressed by chemical formula 1 (chemical formula 1 is as described in the description of the invention).

Description

Lithium secondary battery containing polymer electrolyte

[0001] It relates to a polymer electrolyte and a lithium secondary battery including the same.

[0002]

[0003] The recent rapid proliferation of battery-powered electronic devices, such as mobile phones, laptops, and electric vehicles, has led to a rapid increase in demand for high-energy density, high-capacity secondary batteries. Accordingly, active research and development is underway to improve the performance of lithium secondary batteries.

[0004] A lithium secondary battery is a battery that includes a positive electrode and a negative electrode that contain active materials capable of intercalating and deintercalating lithium ions, and an electrolyte, and produces electrical energy through oxidation and reduction reactions when lithium ions are intercalated / deintercalated from the positive electrode and negative electrode.

[0005]

[0006] One embodiment provides a polymer electrolyte for a lithium secondary battery having improved interfacial stability and thus improved lifespan characteristics.

[0007] Another embodiment provides a lithium secondary battery comprising the polymer electrolyte.

[0008]

[0009] One embodiment is a crosslinked polymer comprising repeating units (A) derived from a crosslinkable monomer comprising an acrylate functional group; and

[0010] A polymer electrolyte comprising an organic solvent including a compound represented by the following chemical formula 1 is provided.

[0011] [Chemical Formula 1]

[0012]

[0013] In the above chemical formula 1,

[0014] R1 is hydrogen, halogen, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C3 to C20 cycloalkenyl group, a substituted or unsubstituted C3 to C20 cycloalkynyl group, a substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C2 to C30 heterocyclic group.

[0015] Another embodiment provides a lithium secondary battery comprising: a positive electrode layer; a negative electrode layer; and an electrolyte layer disposed between the positive electrode layer and the negative electrode layer and including the polymer electrolyte described above.

[0016]

[0017] A lithium secondary battery including a polymer electrolyte according to one embodiment can exhibit excellent life characteristics.

[0018]

[0019] Figure 1 is a schematic diagram illustrating a lithium secondary battery according to an embodiment.

[0020] Figures 2 to 5 are cross-sectional views schematically showing a lithium secondary battery according to one embodiment.

[0021] Figures 6 and 7 are cross-sectional views schematically showing a lithium secondary battery according to one embodiment.

[0022] Figure 8 schematically illustrates the structure of a cross-linked polymer constituting a polymer electrolyte according to one embodiment.

[0023]

[0024] To fully understand the structure and effects of the present invention, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and subject to various modifications. However, the description of these embodiments is provided solely to ensure a complete disclosure of the present invention and to fully inform those skilled in the art of the invention of the scope of the invention.

[0025] In this specification, when a component is referred to as being on another component, it means that it can be formed directly on the other component, or a third component may be interposed between them. Furthermore, in the drawings, the thicknesses of the components are exaggerated for the sake of clarity. Parts designated by the same reference numerals throughout the specification represent the same components.

[0026] Unless otherwise specified herein, the singular may also include the plural. Furthermore, unless otherwise specified, "A or B" may mean "including A, including B, or including A and B." As used herein, "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components.

[0027] As used herein, “combination thereof” may mean mixtures, laminates, composites, copolymers, alloys, blends, and reaction products of the components.

[0028]

[0029] Figure 1 is a schematic conceptual diagram illustrating a lithium secondary battery according to an embodiment. Referring to Figure 1, the lithium secondary battery may include a positive electrode (10), a negative electrode (20), a separator (30), and an electrolyte (ELL).

[0030] The positive electrode (10) and the negative electrode (20) may be spaced apart from each other with a separator (30) therebetween. The separator (30) may be placed between the positive electrode (10) and the negative electrode (20). The positive electrode (10), the negative electrode (20), and the separator (30) may be in contact with the electrolyte (ELL). The positive electrode (10), the negative electrode (20), and the separator (30) may be impregnated in the electrolyte (ELL).

[0031] The electrolyte (ELL) may be a medium for transferring lithium ions between the positive electrode (10) and the negative electrode (20). Within the electrolyte (ELL), the lithium ions may pass through the separator (30) and move toward the positive electrode (10) or the negative electrode (20).

[0032]

[0033] Bipolar (10)

[0034] A positive electrode (10) for a lithium secondary battery may include a current collector (COL1) and a positive electrode active material layer (AML1) formed on the current collector (COL1). The positive electrode active material layer (AML1) includes a positive electrode active material and may further include a binder and / or a conductive material.

[0035] For example, the anode (10) may further include an additive that can act as a sacrificial anode.

[0036] The content of the positive electrode active material in the positive electrode active material layer (AML1) may be 90 wt% to 99.5 wt% with respect to 100 wt% of the positive electrode active material layer (AML1). The contents of the binder and the conductive material may each be 0.5 wt% to 5 wt% with respect to 100 wt% of the positive electrode active material layer (AML1).

[0037] The above binder serves to adhere the positive electrode active material particles well to each other and also to adhere the positive electrode active material well to the current collector (COL1). Representative examples of the binder include, but are not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylic resin, polyester resin, nylon, etc.

[0038] The conductive material is used to provide conductivity to the electrode, and any material that does not cause chemical changes and is electronically conductive can be used in the battery. Examples of the conductive material include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, and carbon nanotube; metal-based materials containing copper, nickel, aluminum, silver, etc. in the form of metal powder or metal fiber; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0039] Al can be used as the current collector (COL1), but is not limited thereto.

[0040]

[0041] positive electrode active material

[0042] As the cathode active material in the cathode active material layer (AML1), a compound capable of reversible intercalation and deintercalation of lithium (lithiated intercalation compound) can be used. Specifically, one or more of a composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof can be used.

[0043] The above composite oxide may be a lithium transition metal composite oxide, and specific examples thereof include lithium nickel-based oxide, lithium cobalt-based oxide, lithium manganese-based oxide, lithium iron phosphate-based compound, cobalt-free nickel-manganese-based oxide, or a combination thereof.

[0044] As an example, a compound represented by any one of the following chemical formulas may be used: Li a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni b Co c L 1 d G e O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); Li a NiG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-b G b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Lia Mn2G b O4(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-g G g PO4(0.90≤a≤1.8, 0≤g≤0.5); Li (3-f) Fe2(PO4)3(0≤f≤2); Li a FePO4(0.90≤a≤1.8).

[0045] In the above chemical formula, A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; L 1 is Mn, Al or a combination thereof.

[0046] For example, the cathode active material may be a high-nickel cathode active material in which the nickel content is 80 mol% or more, 85 mol% or more, 90 mol% or more, 91 mol% or more, or 94 mol% or more and 99 mol% or less, based on 100 mol% of metals excluding lithium in a lithium transition metal composite oxide. The high-nickel cathode active material can realize high capacity and thus can be applied to high-capacity, high-density lithium secondary batteries.

[0047]

[0048] Cathode (20)

[0049] A negative electrode (20) for a lithium secondary battery includes a current collector (COL2) and a negative electrode active material layer (AML2) positioned on the current collector (COL2). The negative electrode active material layer (AML2) includes a negative electrode active material and may further include a binder and / or a conductive material.

[0050] For example, the negative active material layer (AML2) may include 90 to 99 wt% of the negative active material, 0.5 to 5 wt% of the binder, and 0 to 5 wt% of the conductive material.

[0051] The above binder serves to adhere the negative electrode active material particles well to each other and also to adhere the negative electrode active material well to the current collector (COL2). The binder may be a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof.

[0052] Examples of the non-aqueous binder include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or combinations thereof.

[0053] The above-mentioned aqueous binder may be selected from styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluoroelastomer, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenol resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0054] When using an aqueous binder as the above-mentioned negative electrode binder, a cellulose-based compound capable of imparting viscosity may be further included. The cellulose-based compound may be a mixture of one or more of carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, or an alkali metal salt thereof. The alkali metal may be Na, K, or Li.

[0055] The above dry binder is a polymeric material capable of being fiberized, and may be, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or a combination thereof.

[0056] The conductive material is used to provide conductivity to the electrode, and any material that does not cause chemical changes and is electronically conductive can be used in the battery. Specific examples include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metal-based materials in the form of metal powder or metal fibers, including copper, nickel, aluminum, and silver; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0057] The current collector (COL2) may be selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, polymer substrate coated with a conductive metal, and combinations thereof.

[0058]

[0059] Negative active material

[0060] The negative active material in the negative active material layer (AML2) includes a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0061] The material capable of reversibly intercalating / deintercalating the lithium ions may include a carbon-based negative electrode active material, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as natural graphite or artificial graphite in an amorphous, plate-like, flake-like, spherical, or fibrous form, and examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, and the like.

[0062] As the above lithium metal alloy, an alloy of lithium and a metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn can be used.

[0063] As the material capable of doping and dedoping the lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material may be used. The Si-based negative electrode active material may be silicon, a silicon-carbon composite, SiOx (0 < x < 2), a Si-Q alloy (wherein Q is selected from alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements (excluding Si), Group 15 elements, Group 16 elements, transition metals, rare earth elements, and combinations thereof), or a combination thereof. The Sn-based negative electrode active material may be Sn, SnO2, a Sn-based alloy, or a combination thereof.

[0064] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one embodiment, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles. For example, the composite may include secondary particles (cores) in which silicon primary particles are assembled and an amorphous carbon coating layer (shell) positioned on the surface of the secondary particles. The amorphous carbon may also be positioned between the silicon primary particles, such that, for example, the silicon primary particles may be coated with amorphous carbon. The secondary particles may be dispersed and present in an amorphous carbon matrix.

[0065] The silicon-carbon composite may further comprise crystalline carbon. For example, the silicon-carbon composite may comprise a core comprising crystalline carbon and silicon particles and an amorphous carbon coating layer positioned on the surface of the core.

[0066] The above Si-based negative electrode active material or Sn-based negative electrode active material can be used in a mixture with a carbon-based negative electrode active material.

[0067]

[0068] Separator (30)

[0069] Depending on the type of lithium secondary battery, a separator (30) may be present between the positive electrode (10) and the negative electrode (20). As the separator (30), a multilayer film of two or more layers of polyethylene, polypropylene, polyvinylidene fluoride, or these may be used, and of course, a mixed multilayer film such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, or a polypropylene / polyethylene / polypropylene three-layer separator may be used.

[0070] The separator (30) may include a porous substrate and a coating layer including an organic material, an inorganic material, or a combination thereof located on one or both sides of the porous substrate.

[0071] The above porous substrate may be a polymer film formed of any one polymer selected from polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyacetal, polyamide, polyimide, polycarbonate, polyether ketone, polyarylether ketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenylene oxide, cyclic olefin copolymer, polyphenylene sulfide, polyethylene naphthalate, glass fiber, Teflon, and polytetrafluoroethylene, or a copolymer or mixture of two or more thereof.

[0072] The organic material may include a polyvinylidene fluoride polymer or a (meth)acrylic polymer.

[0073] The above inorganic materials are Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, It may include inorganic particles selected from, but not limited to, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof.

[0074] The organic and inorganic substances may be mixed and present in one coating layer, or a coating layer including an organic substance and a coating layer including an inorganic substance may be present in a laminated form.

[0075]

[0076] polymer electrolyte

[0077] A polymer electrolyte according to one embodiment may include a cross-linked polymer and an organic solvent. The polymer electrolyte may correspond to the electrolyte (ELL) described above with reference to FIG. 1.

[0078] cross-linked polymer

[0079] According to one embodiment, a polymer electrolyte may include a crosslinked polymer comprising repeating units (A) derived from a crosslinkable monomer containing an acrylate functional group. In this case, the crosslinked polymer may exhibit improved stability at room temperature and high temperatures. Accordingly, a lithium secondary battery according to one embodiment may exhibit improved capacity characteristics and capacity retention characteristics.

[0080] A crosslinking monomer containing an acrylate functional group may have improved high temperature stability by including two or more double bond functional groups. A crosslinking monomer containing an acrylate functional group may have two or more double bond functional groups, thereby reducing the content of unreacted monomer remaining after a crosslinking reaction during the manufacturing process of a crosslinked polymer. A crosslinking monomer containing an acrylate functional group may have two or more double bond functional groups, thereby preventing side reactions due to unreacted monomers. A lithium secondary battery containing a polymer electrolyte containing a crosslinking monomer containing an acrylate functional group may have improved high temperature capacity characteristics and high temperature life characteristics.

[0081] According to one embodiment, the crosslinking monomer including an acrylate functional group is selected from the group consisting of trimethylolpropane dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, tris(2-hydroxyethyl) isocyanurate triacrylate, ethoxylated glycerin triacrylate, glycerol propoxylate triacrylate, and ethoxylated dipentaerythritol hexaacrylate. hexaacrylate), or dipentaerythritol hexaacrylate, or a combination thereof.

[0082] According to one embodiment, a crosslinked polymer may include a repeating unit (B) derived from an ionic monomer containing an ionic functional group. In this case, the crosslinked polymer may have improved ionic conductivity due to the inclusion of the ionic monomer. Accordingly, a lithium secondary battery according to one embodiment may have improved capacity characteristics and capacity retention characteristics.

[0083] An ionic monomer containing an ionic functional group has improved ionic conductivity, so that lithium ions can be uniformly deposited on an anode, which will be described later. An ionic monomer containing an ionic functional group can effectively prevent the formation of lithium dendrites. According to one embodiment, an ionic monomer can prevent a crosslinking reaction between ionic monomers by containing one double bond functional group. The ionic monomer containing one double bond functional group can be dispersed and arranged at the terminals of the main chain and side chains of a crosslinked polymer in the form of end-capping during a crosslinking reaction. The ionic monomer containing one double bond functional group can prevent charge unevenness due to aggregation of the ionic monomer. The repeating unit (B) derived from a uniformly matched ionic monomer uniformly improves the ionic conductivity of a polymer electrolyte, so that lithium ions can be uniformly deposited on an anode, which will be described later. A lithium secondary battery according to one embodiment can have improved capacity characteristics and life characteristics.

[0084] The ionic functional group may include a cationic functional group, an anionic functional group, or a combination thereof. For example, if the ionic monomer includes a cationic functional group, the ionic monomer may be a cationic monomer. For example, if the ionic monomer includes an anionic functional group, the ionic monomer may be an anionic monomer. For example, if the ionic monomer includes both a cationic functional group and an anionic functional group, the ionic monomer may be a zwitterionic monomer.

[0085] In one embodiment, the cationic functional group may include pyrrolidium, piperidinium, ammonium, imidazolium, phosphonium, or a combination thereof. For example, the cationic functional group may include pyrrolidium, piperidinium, ammonium, imidazolium, or a combination thereof.

[0086] In one embodiment, the anionic functional group may include trifluoromethanesulfonyl imide (TFSI), bis(fluorosulfonyl) imide (FSI), acetate, bromide (Br-), chloride (Cl-), iodide (I-), dicyanamide, hexafluorophosphate, tetrafluoroborate, hydrogen sulfate, or any combination thereof. For example, the anionic functional group may include trifluoromethanesulfonyl imide (TFSI), bis(fluorosulfonyl) imide (FSI), or any combination thereof.

[0087] According to one embodiment, the ionic monomer may include a cationic monomer or a zwitterionic monomer. For example, when the ionic monomer includes a cationic monomer, the cationic monomer may include a cationic functional group and a double bond functional group. For example, when the ionic monomer includes a zwitterionic monomer, the zwitterionic monomer may include an anionic functional group, a cationic functional group, and a double bond functional group.

[0088] In one embodiment, the ionic monomer may comprise a cationic monomer and an anion. In this case, the cationic monomer may comprise a cationic functional group and a double bond functional group. The anion may comprise the anionic functional group. For example, the anion may be the anionic functional group.

[0089] According to one embodiment, the ionic monomer may include a cationic monomer such as a pyrrolidium-allyl monomer, a pyrrolidium-acrylate monomer, an ammonium-aryl monomer, an ammonium-acrylate monomer, or any combination thereof. In this case, the ionic monomer may include an anion such as trifluoromethanesulfonylimide (TFSI), bis(fluorosulfonyl) imide (FSI), acetate, bromide (Br-), chloride (Cl-), iodide (I-), dicyanamide, hexafluorophosphate, tetrafluoroborate, hydrogen sulfate, or any combination thereof.

[0090] For example, a pyrrolidium-allyl monomer may contain allyl and pyrrolidium in one monomer. For example, a pyrrolidium-acrylate monomer may contain acrylate and pyrrolidium in one monomer. For example, an ammonium-allyl monomer may contain allyl and ammonium in one monomer. For example, an ammonium-acrylate monomer may contain acrylate and ammonium in one monomer.

[0091] According to one embodiment, the ionic monomer may include a cationic monomer such as 1-allyl-1-methylpyrrolidium, dimethyl[2-(methacryloyloxy)ethyl]propylaminium, or a combination thereof. For example, the cationic monomer may be dimethyl[2-(methacryloyloxy)ethyl]propylaminium. In this case, the ionic monomer may include an anion such as trifluoromethanesulfonyl imide (TFSI) or bis(fluorosulfonyl) imide (FSI).

[0092] According to one embodiment, the molar ratio of the repeating unit (A) derived from the crosslinkable monomer contained in the crosslinked polymer to the repeating unit (B) derived from the ionic monomer may be 5:5 to 9:1. For example, the molar ratio of the repeating unit (A) derived from the crosslinkable monomer contained in the crosslinked polymer to the repeating unit (B) derived from the ionic monomer may be 5:5 to 8:2, 5:5 to 7:3, or more than 5:5 and less than or equal to 7:3. For example, when the molar ratio of the repeating unit (A) derived from the crosslinkable monomer contained in the crosslinked polymer to the repeating unit (B) derived from the ionic monomer is satisfied, the molar number of the repeating unit (A) derived from the crosslinkable monomer may be greater than or equal to the molar number of the repeating unit (B) derived from the ionic monomer. For example, when the molar number of repeating units (A) derived from a crosslinkable monomer is greater than or equal to the molar number of repeating units (B) derived from an ionic monomer, the content of unreacted monomer is reduced, so that the polymer electrolyte including the crosslinked polymer can have improved high-temperature stability. According to one embodiment, the molar number of repeating units (A) derived from a crosslinkable monomer can be greater than the molar number of repeating units (B) derived from an ionic monomer.

[0093] Figure 8 schematically illustrates the structure of a cross-linked polymer constituting a polymer electrolyte according to one embodiment.

[0094] Referring to Fig. 8, the crosslinked polymer (1) may include a main chain (M) and a plurality of side chains (S) extending from the main chain (M). For example, the plurality of side chains (S) may include a side chain (S1) extending from the main chain (M) and a side chain (S2) extending from the side chain (S1) extending from the main chain (M).

[0095] Referring to Figure 8,

[0096] The main chain (M) and the plurality of side chains (S) may include a terminal portion (E) at which a crosslinking reaction or polymerization reaction is completed.

[0097] For example, at least one terminal portion (E) among the terminal portions (E) included in the main chain (S) and the plurality of side chains (M) may include a repeating unit (B) derived from an ionic monomer.

[0098] According to one embodiment, one or more terminal portions (E) may include a repeating unit (B) derived from the ionic monomer. In this case, the ionic monomer may be uniformly distributed throughout the crosslinked polymer (1) rather than being aggregated. In this case, the ionic conductivity of the polymer electrolyte including the crosslinked polymer (1) may be uniformly improved. A lithium battery including the polymer electrolyte according to an embodiment may have improved lifespan characteristics and capacity characteristics.

[0099] organic solvent

[0100] According to one embodiment, the organic solvent serves as a medium through which ions involved in the electrochemical reaction of the battery can move.

[0101] An organic solvent according to one embodiment may include a compound represented by the following chemical formula 1.

[0102] [Chemical Formula 1]

[0103]

[0104] In the above chemical formula 1,

[0105] R1 may be hydrogen, halogen, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C3 to C20 cycloalkenyl group, a substituted or unsubstituted C3 to C20 cycloalkynyl group, a substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C2 to C30 heterocyclic group.

[0106] According to an embodiment, a polymer electrolyte can be injected in a liquid state into an electrochemical device or the like, and then, through in-situ thermal crosslinking, form an electrolyte in a gel or solid form after cell manufacturing. In one embodiment, the heat treatment can be performed at 60 to 80°C. The compound represented by the above chemical formula 1 decomposes within the above temperature range, thereby inducing the formation of a solid electrolyte interface (SEI) on the surface of the lithium metal, thereby improving the life characteristics of the lithium metal battery.

[0107] According to one embodiment, the compound represented by the above chemical formula 1 may include at least one of the compounds listed in Group 1 below.

[0108] [Group 1]

[0109]

[0110] According to one embodiment, the compound represented by the chemical formula 1 may be included in an amount of 0.1 to 30 wt% based on the total amount of the organic solvent. For example, the compound represented by the chemical formula 1 may be included in an amount of 1 to 30 wt% based on the total amount of the organic solvent, may be included in an amount of 5 to 30 wt% based on the total amount of the organic solvent, may be included in an amount of 1 to 25 wt% based on the total amount of the organic solvent, may be included in an amount of 1 to 20 wt% based on the total amount of the organic solvent, and may be included in an amount of 5 to 20 wt% based on the total amount of the organic solvent. When the compound represented by the chemical formula 1 satisfies the above range, the life characteristics of the lithium metal battery can be improved within a range in which the capacity characteristics are not deteriorated due to the formation of an excessive solid electrolyte interface (SEI).

[0111] The organic solvent according to one embodiment may further include a carbonate-based solvent, an ester-based solvent, an ether-based solvent, a ketone-based solvent, an alcohol-based solvent, an aprotic solvent, or a combination thereof.

[0112] The above carbonate solvent may include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methylethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), fluoroethylene carbonate (FEC), or a combination thereof.

[0113] The above ester solvent may include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, decanolide, valerolactone, mevalonolactone, caprolactone, or a combination thereof.

[0114] Examples of the ether solvents that can be used include dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane (DME), 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, and tetrahydrofuran. In addition, cyclohexanone and the like can be used as ketone solvents. Examples of alcohol solvents that can be used include ethyl alcohol and isopropyl alcohol, and examples of aprotic solvents include nitriles such as R-CN (where R is a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double bond, an aromatic ring, or an ether group); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane and 1,4-dioxolane; It may contain sulfolanes or combinations thereof.

[0115] The above organic solvents can be used alone or in combination of two or more.

[0116] When using the above carbonate solvent, a cyclic carbonate and a chain carbonate may be mixed and used, and the cyclic carbonate and the chain carbonate may be mixed in a mass ratio of 1:1 to 1:9. For example, the cyclic carbonate and the chain carbonate may be mixed in a mass ratio of 1:1 to 1:5, may be mixed in a mass ratio of 1:1 to 1:3, or may be mixed in a mass ratio of 1:1 to 1:2. An organic solvent according to one embodiment may include a cyclic carbonate solvent and a chain carbonate solvent, and the content of the cyclic carbonate solvent may be less than the content of the chain carbonate solvent.

[0117] An organic solvent according to one embodiment may be a mixture of a carbonate solvent and an ester solvent. The organic solvent according to one embodiment may include a carbonate solvent and an ester solvent, and the content of the carbonate solvent may be less than the content of the ester solvent.

[0118] An organic solvent according to one embodiment may be a mixture of two or more ether solvents. For example, an organic solvent according to one embodiment may include 1,2-dimethoxyethane (DME) and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), and the content of 1,2-dimethoxyethane (DME) may be less than the content of 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE).

[0119] For example, according to one embodiment, the organic solvent is 1,2-dimethoxyethane (DME) and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), which can be mixed in a mass ratio of 1:1 to 1:20, can be mixed in a mass ratio of 1:1 to 1:10, or can be mixed in a mass ratio of 1:5 to 1:10.

[0120] The polymer electrolyte according to one embodiment may further include a lithium salt.

[0121] According to one embodiment, the content of the lithium salt may be included in an amount of 20 to 100 wt% of the total amount of the polymer electrolyte.

[0122] According to one embodiment, the lithium salt is LiSCN, LiN(CN)2, Li(CF3SO2)3C, Li(FSO2)2N(LiFSI), LiC4F9SO3, LiN(SO2CF2CF3)2, LiPF3(C2F5)3, LiCl, LiF, LiBr, LiI, LiB(C2O4)2, LiPF6, LiPF5(CF3), LiPF5(C2F5), LiPF5(C3F7), LiPF4(CF3)2, LiPF4(CF3)(C2F5), LiPF3(CF3)3, LiPF3(CF2CF3)3, LiPF4(C2O4)2, LiBF4, LiBF3(C2F5), lithium bis(oxalato)borate (LiBOB), lithium oxalyldifluoroborate, LiODFB), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(trifluoro methanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO2F)2), LiN(SO2C2F5)2, LiCF3SO3, LiAsF6, LiSbF6, LiClO4, or a combination thereof.

[0123] The concentration of the lithium salt according to one embodiment may be 0.1 M to 2 M.

[0124] According to one embodiment, two or more types of lithium salts may be mixed and used. When two types of lithium salts are mixed and used, the concentration of each lithium salt may be 0.1 M to 1 M.

[0125] When the polymer electrolyte contains a lithium salt, the polymer electrolyte may be a polymer solid electrolyte containing a lithium salt.

[0126] The polymer solid electrolyte may, for example, comprise a mixture of a lithium salt and the cross-linked polymer described above. The polymer solid electrolyte may, for example, be a polymer electrolyte that does not comprise a liquid electrolyte.

[0127] According to one embodiment, the polymer solid electrolyte may include a polymer in addition to the cross-linked polymer described above.For example, the polymers include polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyethylene oxide (PEO), poly(styrene-b-ethylene oxide) block copolymer (PS-PEO), poly(styrene-butadiene), poly(styrene-isoprene-styrene), poly(styrene-b-divinylbenzene) block copolymer, poly(styrene-ethylene oxide-styrene) block copolymer, polystyrene sulfonate (PSS), polyvinyl fluoride (PVF, PolyvinylFluoride), polymethyl methacrylate (PMMA, poly(methylmethacrylate), polyethylene glycol (PEG), polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), polyethylenedioxythiophene (PEDOT), polypyrrole (PPY), polyacrylonitrile (PAN), polyaniline, Polyacetylene, Nafion, Aquivion, Flemion, Gore, Aciplex, Morgane ADP, sulfonated poly(ether ether ketone) (SPEEK), sulfonated poly(arylene ether ketone ketone sulfone) (SPAEKKS), sulfonated poly(arylether ketone) (SPAEK), poly[bis(benzimidazobenzisoquinolinones)] (SPBIBI), poly(styrene sulfonate) (PSS), lithium 9,10-diphenylatlacene-2-sulfonate 9,10-diphenylanthracene-2-sulfonate, DPASLi+) or a combination thereof.

[0128] According to one embodiment, the polymer electrolyte may further comprise a liquid electrolyte. For example, the polymer electrolyte may be a gel polymer electrolyte comprising the cross-linked polymer described above and a liquid electrolyte. For example, the liquid electrolyte may be disposed within a cross-linked network formed by the cross-linked polymer.

[0129] According to one embodiment, the liquid electrolyte may include an organic solvent or an ionic liquid. For example, the liquid electrolyte may further include a lithium salt. For example, the liquid electrolyte may be an ionic liquid, an organic solvent, a mixture of a lithium salt and an organic solvent, a mixture of an ionic liquid and an organic solvent, or a mixture of a lithium salt, an ionic liquid, and an organic solvent. Since the organic solvent included in the liquid electrolyte has been described above, a detailed description thereof will be omitted below.

[0130] The above ionic liquid refers to a salt or a room-temperature molten salt that has a melting point below room temperature and is liquid at room temperature and is composed only of ions. The ionic liquid may be, for example, a) one or more cations selected from ammonium, pyrrolidinium, pyridinium, pyrimidinium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazinium, phosphonium, sulfonium, triazolium, and mixtures thereof, and b) BF4. - , PF6 - , AsF6 - , SbF6 - , AlCl4 - , HSO4 - , ClO4 - , CH3SO3 - , CF3CO2 - , Cl - , Br - , I - , BF4 - , SO4 - , CF3SO3 - , (FSO2)2N - , (C2F5SO2)2N -, (C2F5SO2)(CF3SO2)N - , and (CF3SO2)2N - It may include at least one selected from compounds containing at least one anion selected from among.

[0131] For example, the polymer solid electrolyte may be impregnated into an electrolyte solution within a lithium battery to form a gel polymer electrolyte. The gel polymer electrolyte may further include inorganic particles.

[0132] According to one embodiment, the polymer electrolyte may further include a solid electrolyte.

[0133] The solid electrolyte may include, for example, an oxide-based solid electrolyte, a sulfide-based solid electrolyte, or a combination thereof.

[0134] Solid electrolytes are, for example, oxide-based solid electrolytes. Oxide-based solid electrolytes are Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (0 <x<2, 0≤y<3), BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT)(O≤x<1, O≤y<1), PB(Mg3Nb 2 / 3 )O3-PbTiO3(PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, Li3PO4, Li x Ti y (PO4)3(0 <x<2, 0<y<3), Li x Al y Ti z (PO4)3(0 <x<2, 0<y<1, 0<z<3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si yP 3-y O 12 (0≤x≤1, 0≤y 1), Li x La y TiO3(0 <x<2, 0<y<3), Li2O, LiOH, Li2CO3, LiAlO2, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2, Li 3+x La3M2O 12 (M = Te, Nb, or Zr, x is an integer from 1 to 10) is one or more selected from. The solid electrolyte is manufactured by a sintering method, etc. For example, the oxide-based solid electrolyte is Li7La3Zr2O 12 (LLZO) and Li 3+x La3Zr 2-a M a O 12 A garnet-type solid electrolyte selected from (M doped LLZO, M=Ga, W, Nb, Ta, or Al, x is an integer from 1 to 10).

[0135] The solid electrolyte may include a sulfide-based solid electrolyte having excellent lithium ion conductivity characteristics. Examples of the sulfide-based solid electrolyte include Li2S-P2S5, Li2S-P2S5-LiX (X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z. m S n (m, n are positive numbers, capital letter “Z” represents Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, capital letter “M” is one of P, Si, Ge, B, Al, Ga In), Li 7-x PS 6-x Cl x (0≤x≤2), Li7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It may include at least one selected from (0≤x≤2).

[0136] Sulfide-based solid electrolytes include, for example, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It may be an argyrodite-type compound including at least one selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound including at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0137] Alternatively, the sulfide-based solid electrolyte is Li 7-a M a PS 6-c X cIt may be an argyrodite-type compound containing (0≤a≤2, (0≤c≤2)), where X may be F, Br, Cl, or a combination thereof. M is candium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), arsenic (As), antimony (Sb), bismuth (Bi), or a combination thereof. Can be.

[0138] The density of the argyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. Since the argyrodite-type solid electrolyte has a density of 1.5 g / cc or more, the internal resistance of the all-solid-state battery is reduced, and the defect of the solid electrolyte membrane being penetrated and short-circuited due to the formation of lithium dendrites can be prevented. The elastic modulus of the solid electrolyte may be, for example, 15 GPa to 35 GPa.

[0139]

[0140] lithium secondary battery

[0141] Lithium secondary batteries (LIBs) can be classified into cylindrical, prismatic, pouch-shaped, coin-shaped, etc., depending on their shape. FIGS. 2 to 5 are schematic diagrams illustrating lithium secondary batteries (LIBs) according to one embodiment, wherein FIG. 2 can be said to be a cylindrical battery, FIG. 3 a prismatic battery, and FIGS. 4 and 5 a pouch-shaped battery. Referring to FIGS. 2 to 4, the lithium secondary battery (LIB) may include an electrode assembly (40) having a separator (30) interposed between a positive electrode (10) and a negative electrode (20), and a case (50) in which the electrode assembly (40) is housed. The positive electrode (10), the negative electrode (20), and the separator (30) may be impregnated with an electrolyte. The electrolyte may include the polymer electrolyte described above. The lithium secondary battery (LIB) may include a sealing member (60) that seals the case (50), as shown in FIG. 2. In addition, in FIG. 3, the lithium secondary battery may include a positive lead tab (11), a positive terminal (12), a negative lead tab (21), and a negative terminal (22). As in FIGS. 4 and 5, the lithium secondary battery (LIB) may include electrode tabs (70), i.e., a positive tab (71) and a negative tab (72), which serve as electrical paths for inducing current formed in the electrode assembly (40) to the outside.

[0142] A lithium secondary battery according to one embodiment may be a lithium metal battery. A lithium metal battery according to one embodiment will be described in detail with reference to FIGS. 6 and 7.

[0143] For example, referring to FIG. 6, the lithium secondary battery may be a non-cathode lithium metal battery (FLMB). For example, referring to FIG. 7, the lithium secondary battery may be a lithium metal battery (LMB).

[0144] Referring to FIG. 6, a non-cathode lithium metal battery (FLMB) according to one embodiment may include a cathode layer (100), a cathode current collector (210) facing the cathode layer (100), and an electrolyte layer (300) disposed between the cathode layer (100) and the cathode current collector (210). The electrolyte layer (300) may include the polymer electrolyte described above. The cathode may include a cathode current collector (110) free of a cathode active material layer. The cathode layer (100) may include a cathode current collector (110) and a cathode active material layer (120) disposed on the cathode current collector (110).

[0145] Referring to FIG. 7, a lithium metal battery (LMB) according to one embodiment may further include a lithium metal layer (220) disposed between a negative electrode current collector (210) and an electrolyte layer (300). The lithium metal layer (220) may include lithium metal or a lithium alloy. For example, the lithium metal layer (220) may be dissociated into lithium ions and metal cations during a discharge process, so that the thickness of the lithium metal layer (220) may decrease. For example, the lithium metal layer (220) may be electrodeposited with lithium ions during a charge process, so that the thickness of the lithium metal layer (220) may increase.

[0146]

[0147] A lithium secondary battery according to one embodiment can be applied to automobiles, mobile phones, and / or various types of electrical devices, and the present invention is not limited thereto.

[0148] Hereinafter, examples and comparative examples according to one embodiment are described. However, the following examples are only examples, and the present invention is not limited to the following examples.

[0149]

[0150] Example 1

[0151] Manufacturing of polymer electrolytes

[0152] Trimethylolpropane trimethacrylate (TMPTMA) as a crosslinking monomer and dimethyl[2-(methacryloyloxy)ethyl] propylaminium-bis(fluorosulfonyl) imide as an ionic monomer were mixed with the liquid electrolyte. The liquid electrolyte was prepared by dissolving 0.6 M LiDFOB and 0.6 M LiBF4 in an organic solvent. The organic solvent was prepared by mixing FEC, DEC, and a compound represented by the following chemical formula 2. The mixing weight ratio of FEC, DEC, and the compound represented by the following chemical formula 2 in the organic solvent was 42:53:5.

[0153] [Chemical Formula 2]

[0154]

[0155] A polymer electrolyte composition was obtained by adding tert-butyl peroxypivalate as a thermal polymerization initiator to the above mixture. The content of the thermal polymerization initiator was mixed at 5 parts by weight based on 100 parts by weight of the total weight of the crosslinkable monomer.

[0156] Manufacturing of lithium secondary batteries

[0157] LiNi 0.6 Co 0.2 Al 0.2 O2, a conductive agent (Super-P; Timcal Ltd.), a binder (PVdF; Solvay), and N-methylpyrrolidone were mixed to obtain a cathode composition. LiNi in the cathode composition 0.6 Co 0.2 Al 0.2 The mixing weight ratio of O2, the conductive agent, and the polymer electrolyte was 95:3:2.

[0158] The above positive electrode composition was coated on top of aluminum foil (thickness: about 10 ㎛), dried at 50°C, and the dried resultant was dried in a vacuum at about 120°C to manufacture a positive electrode.

[0159] A separator (PE; 20 μm) was placed between the positive electrode obtained through the above process and a copper (Cu) current collector with a thickness of 10 μm, and an electrolyte was injected in a weight of 6 g / Ah relative to the positive electrode capacity, followed by sealing and heat curing at 70°C for 2 hours to manufacture a lithium metal battery (pouch cell).

[0160]

[0161] Example 2

[0162] A lithium metal battery was manufactured in the same manner as in Example 1, except that the mixing weight ratio of FEC, DEC, and the compound represented by the above chemical formula 2 in the organic solvent was 42:48:10.

[0163]

[0164] Example 3

[0165] A lithium metal battery was manufactured in the same manner as in Example 1, except that the mixing weight ratio of FEC, DEC, and the compound represented by the above chemical formula 2 in the organic solvent was 42:43:15.

[0166]

[0167] Example 4

[0168] An organic solvent was prepared by mixing FEC, DEC, and a compound represented by the following chemical formula 3, and a lithium metal battery was prepared in the same manner as in Example 1, except that the mixing weight ratio of FEC, DEC, and the compound represented by the following chemical formula 3 in the organic solvent was 42:53:5.

[0169] [Chemical Formula 3]

[0170]

[0171] Example 5

[0172] An organic solvent was prepared by mixing FEC, DEC, and the compound represented by the above chemical formula 3, and a lithium metal battery was prepared in the same manner as in Example 1, except that the mixing weight ratio of FEC, DEC, and the compound represented by the above chemical formula 3 in the organic solvent was 42:48:10.

[0173]

[0174] Example 6

[0175] An organic solvent was prepared by mixing FEC, DEC, and the compound represented by the above chemical formula 3, and a lithium metal battery was prepared in the same manner as in Example 1, except that the mixing weight ratio of FEC, DEC, and the compound represented by the above chemical formula 3 in the organic solvent was 42:43:15.

[0176]

[0177] Example 7

[0178] An organic solvent was prepared by mixing FEC, PP, and the compound represented by the above chemical formula 3, and a lithium metal battery was prepared in the same manner as in Example 1, except that the mixing weight ratio of FEC, PP, and the compound represented by the above chemical formula 3 in the organic solvent was 42:48:10.

[0179]

[0180] Example 8

[0181] The lithium salt was prepared by mixing 1.0 M LiFSI, the organic solvent was 1,2-dimethoxyethane (DME) and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) ether solvent, and the compound represented by the above chemical formula 2, and a lithium metal battery was prepared in the same manner as in Example 1, except that the lithium salt was LiFSI and the mixing weight ratio of DME, TTE, and the compound represented by the above chemical formula 2 in the organic solvent was 10:85.9:4.1.

[0182]

[0183] Example 9

[0184] The lithium salt was prepared by mixing 1.0 M LiFSI, the organic solvent was 1,2-dimethoxyethane (DME) and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) ether solvent, and the compound represented by the above chemical formula 3, and a lithium metal battery was prepared in the same manner as in Example 1, except that the lithium salt was LiFSI and the mixing weight ratio of DME, TTE, and the compound represented by the above chemical formula 3 in the organic solvent was 10:85.5:4.6.

[0185]

[0186] Comparative Example 1

[0187] An organic solvent was prepared by mixing FEC and DEC, and a lithium metal battery was prepared in the same manner as in Example 1, except that the mixing weight ratio of FEC and DEC in the organic solvent was 42:58.

[0188]

[0189] Comparative Example 2

[0190] An organic solvent was prepared by mixing FEC and PP, and a lithium metal battery was prepared in the same manner as in Example 1, except that the mixing weight ratio of FEC and PP in the organic solvent was 42:58.

[0191]

[0192] Comparative Example 3

[0193] A lithium metal battery was manufactured in the same manner as in Example 1, except that the lithium salt was LiFSI, the organic solvent was prepared by mixing 1,2-dimethoxyethane (DME) and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) ether solvents, and the mixing weight ratio of the organic solvents was 13.4:86.6.

[0194]

[0195] The composition of the polymer electrolyte manufactured according to the examples and comparative examples is shown in Table 1 below.

[0196] Polymer electrolyte FEC (wt%) DEC (wt%) Methyl Methanesulfonate (wt%) Example 1 42535 Example 2 424810 Example 3 424315 Polymer electrolyte FEC (wt%) DEC (wt%) Ethyl Methansulfonate (wt%) Example 4 42535 Example 5 424810 Example 6 424315 Polymer electrolyte FEC (wt%) Propyl Propionate (wt%) Ethyl Methansulfonate (wt%) Example 7 424810 Polymer electrolyte DME (wt%) TTE (wt%) Methyl Methanesulfonate (wt%) Example 8 1085.94.1 Polymer electrolyte DME (wt%) TTE (wt%) Ethyl Methanesulfonate (wt%) Example 91085.54.6 Polymer electrolyte FEC (wt%) DEC (wt%) Comparative example 14258 Polymer electrolyte FEC (wt%) Propyl Propionate (wt%) Comparative example 24258 Polymer electrolyte DME (wt%) TTE (wt%) Comparative example 313.486.6

[0197]

[0198] Evaluation example: Charge / discharge characteristics

[0199] Lithium metal batteries (pouch cells) manufactured according to Examples 1 to 9 and Comparative Examples 1 to 3 were charged at a constant current of 0.1 C at 45°C until the voltage reached 4.30 V (vs. Li), and then cut-off was achieved at a current of 0.05 C while maintaining 4.30 V in constant voltage mode. Subsequently, discharge was performed at a constant current of 0.1 C until the voltage reached 3.6 V (vs. Li) (formation stage, 1st cycle). This charge-discharge process was repeated twice more to complete the formation process.

[0200] The lithium battery that had gone through the above-described Mars step was charged at a constant current of 0.2 C until the voltage reached 4.3 V (vs. Li), and then cut-off was achieved at a current rate of 0.05 C while maintaining 4.3 V in constant voltage mode. After charging, constant current discharge was performed at 0.5 C until the cut-off voltage of 3.6 V was reached. The above-described charge and discharge process was repeated a total of 50 times.

[0201] In all of the above charge / discharge cycles, a pause of 10 minutes was allowed after each charge / discharge cycle. Here, the capacity retention rate at the 50th cycle is defined by Equation 1 below.

[0202] [Formula 1]

[0203] Capacity retention rate (%) = (50 th Discharge capacity in cycles / 1 st Discharge capacity in cycle) X 100(%)

[0204] The capacity retention rate and discharge capacity of the lithium metal batteries manufactured according to Examples 1 to 9 and Comparative Examples 1 to 3 are shown in Table 2 below.

[0205] Organic solvent 50 th Cycle capacity (mAh) 50 thCycle Capacity Retention Rate (%) Example 1 FEC+DEC+Methyl Methanesulfonate 15.983390.4 Example 2 FEC+DEC+Methyl Methanesulfonate 16.000891.2 Example 3 FEC+DEC+Methyl Methanesulfonate 16.243592.7 Example 4 FEC+DEC+Ethyl Methanesulfonate 15.744189.0 Example 5 FEC+DEC+Ethyl Methanesulfonate 15.801890.0 Example 6 FEC+DEC+Ethyl Methanesulfonate 16.056391.7 Example 7 FEC+Propyl propionate+Ethyl Methanesulfonate 15.796688.1 Example 8 DME + TTE + Methyl Methanesulfonate 15.355687.5 Example 9 DME + TTE + Ethyl Methanesulfonate 15.741689.9 Comparative Example 1 FEC + DEC 15.099287.0 Comparative Example 2 FEC + PP 15.101785.9 Comparative Example 3 DME + TTE 14.701184.7

[0206] Referring to Table 2, Examples 1 to 9 had superior capacity characteristics and capacity retention characteristics compared to Comparative Examples 1 to 3. Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the claims, the detailed description of the invention, and the attached drawings, and it is obvious that this also falls within the scope of the present invention.

Claims

1. A crosslinked polymer comprising a repeating unit (A) derived from a crosslinkable monomer containing an acrylate functional group; and A polymer electrolyte comprising an organic solvent containing a compound represented by the following chemical formula 1: [Chemical Formula 1] In the above chemical formula 1, R1 is hydrogen, halogen, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C3 to C20 cycloalkenyl group, a substituted or unsubstituted C3 to C20 cycloalkynyl group, a substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C2 to C30 heterocyclic group.

2. In paragraph 1, The compound represented by the above chemical formula 1 is a polymer electrolyte comprising at least one of the compounds listed in Group 1 below: [Group 1] 3. In paragraph 1, A polymer electrolyte, wherein the compound represented by the above chemical formula 1 is contained in an amount of 0.1 to 30 wt% of the total amount of the organic solvent.

4. In paragraph 1, The crosslinking monomer is selected from the group consisting of trimethylolpropane dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, tris(2-hydroxyethyl) isocyanurate triacrylate, ethoxylated glycerin triacrylate, glycerol propoxylate triacrylate, ethoxylated dipentaerythritol hexaacrylate, or A polymer electrolyte comprising dipentaerythritol hexaacrylate or a combination thereof.

5. In paragraph 1, The above crosslinked polymer further comprises a polymer electrolyte comprising a repeating unit (B) derived from an ionic monomer containing an ionic functional group.

6. In paragraph 5, The above cross-linked polymer comprises a main chain and a plurality of side chains extending from the main chain, A polymer electrolyte, wherein at least one of the terminal portions of the main chain and the plurality of side chains comprises a repeating unit (B) derived from the ionic monomer.

7. In paragraph 5, A polymer electrolyte wherein the ionic functional group comprises a cationic functional group, an anionic functional group, or a combination thereof.

8. In paragraph 7, A polymer electrolyte wherein the cationic functional group comprises pyrrolidium, piperidinium, ammonium, imidazolium, phosphonium or a combination thereof.

9. In paragraph 7, The above anionic functional groups include trifluoromethanesulfonyl imide (TFSI), bis(fluorosulfonyl) imide (FSI), acetate, and bromide (Br). - ), chloride (Cl - ), iodide (I - ), dicyanamide, hexafluorophosphate, tetrafluoroborate, hydrogen sulfate, or any combination thereof.

10. In paragraph 5, A polymer electrolyte in which the molar ratio of repeating units (A) derived from a crosslinkable monomer contained in the above crosslinked polymer to repeating units (B) derived from an ionic monomer is 5:5 to 9:

1.

11. In paragraph 1, A polymer electrolyte wherein the organic solvent comprises a carbonate solvent.

12. In paragraph 11, A polymer electrolyte, wherein the carbonate solvent comprises dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methylethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), fluoroethylene carbonate (FEC), or a combination thereof.

13. In paragraph 11, The above carbonate solvent is a polymer electrolyte including diethyl carbonate (DEC) and fluoroethylene carbonate (FEC).

14. In paragraph 1, A polymer electrolyte wherein the organic solvent comprises an ester solvent.

15. In paragraph 14, The polymer electrolyte comprises the ester solvent selected from the group consisting of methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, n-propyl propionate (PP), γ-butyrolactone, decanolide, valerolactone, mevalonolactone, caprolactone, or a combination thereof.

16. In paragraph 1, A polymer electrolyte wherein the organic solvent comprises an ether solvent.

17. In paragraph 1, The above polymer electrolyte further comprises a lithium salt; The above lithium salts are LiSCN, LiN(CN)2, Li(CF3SO2)3C, Li(FSO2)2N(LiFSI), LiC4F9SO3, LiN(SO2CF2CF3)2, LiPF3(C2F5)3, LiCl, LiF, LiBr, LiI, LiB(C2O4)2, LiPF6, LiPF5(CF3), LiPF5(C2F5), LiPF5(C3F7), LiPF4(CF3)2, LiPF4(CF3)(C2F5), LiPF3(CF3)3, LiPF3(CF2CF3)3, LiPF4(C2O4)2, LiBF4, LiBF3(C2F5), lithium bis(oxalato)borate (LiBOB), lithium oxalyldifluoroborate (LiODFB), lithium A polymer electrolyte comprising lithium difluoro(oxalato)borate (LiDFOB), lithium bis(trifluoro methanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO2F)2), LiN(SO2C2F5)2, LiCF3SO3, LiAsF6, LiSbF6, LiClO4, or a combination thereof.

18. Bipolar layer; cathode layer; and A lithium secondary battery comprising an electrolyte layer disposed between the positive electrode layer and the negative electrode layer and including the polymer electrolyte of claim 1.

19. In paragraph 18, The above cathode layer includes a cathode current collector, A lithium secondary battery in which the above negative electrode layer is free of a negative electrode active material layer.

20. In paragraph 19, A lithium secondary battery further comprising a lithium metal layer disposed between the negative electrode current collector and the electrolyte layer.

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