Lithium secondary battery and method for manufacturing the same

Abstract

The present invention relates to a lithium secondary battery including a solid-liquid hybrid electrolyte membrane having a nonwoven fabric substrate layer and a porous structure layer, and a method for manufacturing the same. According to one embodiment of the present invention, it is possible to provide a lithium secondary battery including a solid-liquid hybrid electrolyte membrane having improved mechanical strength and ionic conductivity compared to conventional batteries, and a method for manufacturing the same.

Description

Technical Field

[0001] The present invention relates to a lithium secondary battery including a solid-liquid hybrid electrolyte membrane and a method for manufacturing the same. This application claims priority based on Korean Patent Application No. 10-2020-0019877 filed on February 18, 2020.

Background Art

[0002] As the use of vehicles, computers, and mobile terminals increases, the importance of lithium secondary batteries is increasing. In particular, the development of lithium secondary batteries that are lightweight and have a high energy density is required.

[0003] Such a lithium secondary battery is manufactured by injecting a liquid electrolyte after interposing a separator between a positive electrode and a negative electrode, or by interposing a solid electrolyte membrane between the positive electrode and the negative electrode.

[0004] However, in a lithium ion battery using a liquid electrolyte, since the negative electrode and the positive electrode are partitioned by a separator, if the separator is damaged due to deformation or an external impact, a short circuit may occur, leading to risks such as overheating or explosion.

[0005] On the other hand, a lithium secondary battery using a solid electrolyte has the advantages that the safety of the battery is increased, leakage of the electrolyte can be prevented, the reliability of the battery is improved, and it is easy to manufacture a thin battery. However, even when using a solid electrolyte, there is still a need to develop a solid electrolyte membrane having a high energy density and improved processability. In addition, in the case of a solid electrolyte, there is a problem that the performance deteriorates due to low ionic conductivity, and there remains a technical problem to be solved that the mechanical strength is not high.

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention is for solving the above-described technical problems, and aims to provide a lithium secondary battery including a solid-liquid hybrid electrolyte membrane in which the thickness is reduced compared to currently commercial solid electrolyte membranes, while ensuring ionic conductivity.

[0007] Also, it aims to provide a lithium secondary battery including a solid-liquid hybrid electrolyte membrane in which the mechanical strength is improved, despite being a thin film compared to currently commercial solid electrolyte membranes.

[0008] Also, it aims to provide a lithium secondary battery including a solid-liquid hybrid electrolyte membrane that can be formed into a thinner film compared to currently commercial solid electrolyte membranes, and in which the energy density per weight compared to the thickness is improved.

[0009] On the other hand, other objects and advantages of the present invention will be understood from the following description. Also, the objects and advantages of the present invention can be realized by the means, methods or combinations thereof shown in the claims.

Means for Solving the Problems

[0010] One aspect of the present invention provides a lithium secondary battery according to the following embodiments.

[0011] Specifically, a lithium secondary battery including a first electrode and a second electrode having opposite polarities to each other, and a solid-liquid hybrid electrolyte membrane interposed between the first electrode and the second electrode, wherein the solid-liquid hybrid electrolyte membrane includes a nonwoven fabric base layer, and a porous structure layer formed on at least one surface of the nonwoven fabric base layer, the nonwoven fabric base layer has a fine pore structure formed by a fine structure of polymer fibrils, and solid polymer particles are dispersed in the fine pore structure or the liquid electrolyte is impregnated therein. The porous structure layer is in a state where the solid polymer particles are filled and in contact with each other, and a pore structure is formed between the solid polymer particles. The liquid electrolyte surrounds the portions where the solid polymer particles are in surface contact with each other, or a part or the entire surface of the solid polymer particles. The content of the liquid electrolyte is 50 to 70% by weight based on 100% by weight of the total content of the solid polymer particles and the liquid electrolyte. The ionic conductivity of the solid-liquid hybrid electrolyte membrane is 1×10 -5 ~1×10 -1 S / cm, which is characterized by this.

[0012] At this time, the polymer fibrils have an average diameter of 0.005 μm to 5 μm, and the nonwoven fabric base layer has pores with a diameter of 0.05 μm to 30 μm and can have a porosity in the range of 50 to 80%.

[0013] At this time, the polymer fibrils can be one or a mixture of two or more selected from the group consisting of polyolefin, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyester, nylon, polyimide, polybenzoxazole, polytetrafluoroethylene, polyarylene ether sulfone, polyether ether ketone, and copolymers thereof.

[0014] The solid polymer particles can be an engineering plastic resin.

[0015] The solid polymer particles can include any one or two or more of polyphenylene oxide, polyether ether ketone, polyimide, polyamideimide, liquid crystal polymer, polyetherimide, polysulfone, polyarylate, polyethylene terephthalate, polybutylene terephthalate, polyoxymethylene, polycarbonate, polypropylene, polyethylene, and polymethyl methacrylate.

[0016] The thickness of the non-woven fabric base layer is 5 μm to 100 μm, and the thickness of the porous structure layer can be 5 μm to 500 μm.

[0017] The first electrode or the second electrode contains a solid electrolyte, and the thickness of the solid-phase - liquid-phase hybrid electrolyte membrane can be 10 to 50 μm.

[0018] The mechanical strength of the solid-phase - liquid-phase hybrid electrolyte membrane is 500 kgf / cm 2 ~5000 kgf / cm 2 and can be such.

[0019] The thickness of the solid-phase - liquid-phase hybrid electrolyte membrane can be 5 μm to 500 μm.

[0020] The lithium secondary battery can be a lithium-ion secondary battery or an all-solid-state battery.

[0021] The first electrode and the second electrode can each independently contain a solid electrolyte or not contain it.

[0022] The porous structure layer can be directly coated and formed on the first electrode or the second electrode independently.

[0023] Another aspect of the present invention provides a method for manufacturing a lithium secondary battery according to the following embodiments.

[0024] Specifically, A method for manufacturing a lithium secondary battery including a first electrode and a second electrode having opposite polarities to each other, and a solid-phase - liquid-phase hybrid electrolyte membrane interposed between the first electrode and the second electrode, (S1) preparing a dispersion liquid containing solid polymer particles and a liquid electrolyte; (S2) coating the dispersion liquid on the first electrode to form a porous structure layer; (S3) sequentially laminating and pressing a nonwoven fabric substrate and a second electrode having a polarity opposite to that of the first electrode on the porous structure layer to produce a solid-liquid hybrid electrolyte membrane including a nonwoven fabric substrate layer; The content of the liquid electrolyte is characterized in that it is 50% to 70% with respect to 100% by weight of the total content of the solid-liquid hybrid electrolyte membrane.

[0025] The first electrode may be a positive electrode and the second electrode may be a negative electrode, or the first electrode may be a negative electrode and the second electrode may be a positive electrode.

[0026] The nonwoven fabric substrate layer has a fine pore structure formed by the fine structure of polymer fibrils, and solid polymer particles are dispersed in the fine pore structure or the liquid electrolyte is impregnated therein. The porous structure layer is in a state where the solid polymer particles are filled and in contact with each other, and a pore structure is formed between the solid polymer particles. The liquid electrolyte may be at a portion where the solid polymer particles are in surface contact with each other or may surround the surface of the solid polymer particles.

[0027] The nonwoven fabric substrate layer may include one or a mixture of two or more selected from the group consisting of polyolefin, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyester, nylon, polyimide, polybenzoxazole, polytetrafluoroethylene, polyarylene ether sulfone, polyether ether ketone, and copolymers thereof.

[0028] The solid polymer particles may be an engineering plastic resin.

[0029] The liquid electrolyte is A + B - is a salt having a structure such as A + includes ions consisting of an alkali metal cation or a combination thereof, and B - is PF6 - BF4 - Cl - Br -, I - , ClO4 - , AsF6 - , CH3CO2 - , CF3SO3 - , N(CF3SO2)2 - , C(CF2SO2)3 - or a salt containing an ion composed of these combinations.

[0030] The lithium secondary battery can be a lithium-ion secondary battery or an all-solid-state battery.

[0031] The first electrode and the second electrode can each independently contain a solid electrolyte or not contain it.

Advantages of the Invention

[0032] According to one aspect of the present invention, a lithium secondary battery including a solid-phase - liquid-phase hybrid electrolyte membrane that can be deformed by using solid polymer particles instead of inorganic particles can be provided.

[0033] Also, by using a polymer in a compressible particle form, a lithium secondary battery including a solid-phase - liquid-phase hybrid electrolyte membrane with improved mechanical strength can be provided. Since no solid electrolyte is used, a solid-phase - liquid-phase hybrid electrolyte membrane that can be deformed by external pressure can be provided. Also, since the polymer particles are physically bonded to each other, it is advantageous for the formation of porosity and pore channels.

[0034] According to one aspect of the present invention, since no binder polymer is used, a solid-phase - liquid-phase hybrid electrolyte membrane with low resistance can be provided.

[0035] Also, by containing a certain amount of liquid electrolyte, the ionic conductivity is high, and by using a non-woven fabric substrate, the mechanical strength is high, and a lithium secondary battery including a solid-phase - liquid-phase hybrid electrolyte membrane in which the non-woven fabric substrate is impregnated with the liquid electrolyte and the ionic conductivity is improved can be provided.

[0036] The drawings attached to this specification illustrate desirable embodiments of the present invention and serve to further understand the technical idea of the present invention together with the content of the invention. Therefore, the present invention should not be construed as being limited only to the matters described in the drawings. On the other hand, the shape, size, scale, or ratio of elements in the drawings attached to this specification may be exaggerated for the purpose of emphasizing a clearer explanation.

Brief Description of the Drawings

[0037]

Figure 1

Figure 2

Figure 3a

Figure 3b

Figure 3c

Modes for Carrying Out the Invention

[0038] Hereinafter, embodiments of the present invention will be described in detail. Prior to this, the terms and words used in this specification and the claims should not be construed as being limited to their ordinary or dictionary meanings. The inventor himself / herself must interpret them in accordance with the meaning and concept corresponding to the technical idea of the present invention in accordance with the principle that the concept of the terms can be appropriately defined in order to explain the invention in the best way. Therefore, it must be understood that the configurations shown in the embodiments described in this specification are only the most desirable embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, there may be various equivalents and modifications that can replace them at the time of this application.

[0039] Throughout this specification, unless otherwise specified, when a part "includes" other components, it means that it may further include other components rather than excluding other components.

[0040] Also, throughout this specification, terms such as "about" and "substantially" are used to mean a value that is the same as or close to the recited value when manufacturing and material tolerances inherent in the recited meaning are presented, and are used to prevent unscrupulous infringers from improperly using the disclosed content where exact or absolute numerical values are recited to assist in the understanding of the present application.

[0041] Throughout this specification, the description "A and / or B" means "A, B, or all of these".

[0042] Specific terms in the detailed description are used for convenience and are not restrictive. The words "right", "left", "upper surface", and "lower surface" indicate directions in the drawings for reference. The words "inside" and "outside" indicate the directions towards and away from the geometric center of the specified device, system, and its components, respectively. The words "front", "rear", "above", "below", and their related words and phrases indicate positions and orientations in the drawings for reference and are not restrictive. Such terms include the above words, their derivatives, and words with similar meanings.

[0043] The present invention relates to a lithium secondary battery including a solid-phase - liquid-phase hybrid electrolyte membrane and a method for manufacturing the same.

[0044] Specifically, a lithium secondary battery according to an aspect of the present invention includes a first electrode and a second electrode having opposite polarities to each other, and a solid-phase - liquid-phase hybrid electrolyte membrane interposed between the first electrode and the second electrode, wherein the solid-phase - liquid-phase hybrid electrolyte membrane includes a non-woven fabric base layer and a porous structure layer, and contains a predetermined amount of liquid electrolyte.

[0045] At this time, the non-woven fabric base layer has a fine pore structure formed by the fine structure of polymer fibrils, and solid polymer particles are dispersed in the fine pore structure or the liquid electrolyte is impregnated therein. The porous structure layer is in a state where the solid polymer particles are filled and in contact with each other, and a pore structure is formed between the solid polymer particles. The liquid electrolyte is in contact with the part where the solid polymer particles are in surface contact, or surrounds a part or the entire surface of the solid polymer particles. The content of the liquid electrolyte is characterized in that it is 50% to 70% by weight based on 100% by weight of the total content of the solid polymer particles and the liquid electrolyte.

[0046] FIG. 1 is a diagram schematically showing the structure of a solid-liquid hybrid electrolyte membrane according to an embodiment of the present invention, FIG. 2 is a diagram schematically showing the structure of an all-solid-state battery including the solid-liquid hybrid electrolyte membrane according to an embodiment of the present invention, and FIGS. 3a to 3c are diagrams schematically showing a method for manufacturing a lithium secondary battery including the solid-liquid hybrid electrolyte membrane according to an embodiment of the present invention. Hereinafter, the present invention will be described in more detail with reference to the drawings.

[0047] Referring to FIG. 1, in one embodiment of the present invention, the solid-liquid hybrid electrolyte membrane 100 includes a non-woven fabric base layer 110 and a porous structure layer 120.

[0048] The non-woven fabric base layer 110 includes a non-woven fabric base material in which a fine pore structure is formed by the fine structure of polymer fibrils.

[0049] At this time, solid polymer particles are dispersed in the fine pore structure or the liquid electrolyte is impregnated therein. In other words, the polymer fibrils and the solid polymer particles are intertwined, and the surface of the polymer fibrils and / or the surface of the solid polymer particles is coated with the liquid electrolyte.

[0050] In the present invention, the "polymer fibril" means a structure formed by the chains of the polymer constituting the nonwoven fabric base material layer being stretched and oriented in the longitudinal direction during the manufacturing process of the nonwoven fabric, so that the bonding force between adjacent molecular chains is increased and they aggregate in the longitudinal direction.

[0051] The nonwoven fabric base material layer may be formed by laminating a plurality of polymer fibrils regularly or irregularly arranged with each other in layers.

[0052] Thus, in one embodiment of the present invention, the solid-liquid hybrid electrolyte membrane includes a nonwoven fabric base material layer, and by including solid polymer particles or a liquid electrolyte in the nonwoven fabric base material layer, the mechanical strength can be increased and the ionic conductivity can be improved.

[0053] At this time, the polymer fibril can be, but is not limited to, polyolefin, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyester, nylon, polyimide, polybenzoxazole, polytetrafluoroethylene, polyarylene ether sulfone, polyether ether ketone, copolymers thereof or mixtures thereof.

[0054] Among these, specific examples of polyolefin include polyethylene such as low-density polyethylene, high-density polyethylene, and linear low-density polyethylene produced by copolymerizing ethylene with one or more C3~C 12 alpha-olefins; and polypropylene such as isotactic polypropylene, atactic polypropylene, and syndiotactic polypropylene, but are not limited thereto. Polyolefin is a substance widely used in the manufacture of separator base materials for secondary batteries.

[0055] Since the solid polymer particles are dispersed in the pores formed by the polymer fibrils, the mechanical strength can be further enhanced compared to the case where only the conventional polymer fibrils themselves or the solid electrolyte exists. In addition, since the liquid electrolyte is impregnated in the fine pore structure formed by the fine structure of the polymer fibrils, adverse effects such as an increase in resistance can be minimized, and the ionic conductivity can be increased.

[0056] The polymer fibrils can have an average diameter of 0.005 μm to 5 μm. Within the above numerical range, the mechanical strength of the non-woven fabric base material layer does not decrease, and the porosity and thickness of the non-woven fabric base material layer can be easily adjusted.

[0057] The non-woven fabric base material produced by such polymer fibrils can have pores with an average diameter of 0.05 μm to 100 μm. If the non-woven fabric base material in the non-woven fabric base material layer satisfies the pore diameter within the above numerical range, the desired ionic conductivity and mechanical strength can be obtained even when the non-woven fabric base material is used for a solid-liquid hybrid electrolyte membrane.

[0058] Alternatively, the size of the pores in the fine pore structure within the non-woven fabric base material can be 0.2 times to 100 times, 0.5 times to 80 times, or 1 time to 50 times the average diameter (D 50 ) of the solid polymer particles in particle form. Within the above numerical range, the solid polymer particles are easily bound in the pores of the non-woven fabric, and the short-circuit occurrence rate after manufacturing the electrode assembly can be reduced.

[0059] In addition, the non-woven fabric base material can have a porosity in the range of 40% to 95%. The unit % of the porosity means vol% unless otherwise specified. If the non-woven fabric base material satisfies the porosity within the above numerical range, the desired ionic conductivity, mechanical strength, and morphological stability can be obtained even when the non-woven fabric base material is used for a solid-liquid hybrid electrolyte membrane.

[0060] The "pores" in the present invention have various forms of pore structures, and if even one of the average sizes of the pores measured using a porosimeter or observed on an FE-SEM (Field Emission Scanning Electron Microscope) satisfies the above-described conditions, it is included in the present invention.

[0061] In a specific embodiment of the present invention, the thickness of the non-woven fabric base layer can be 5 μm to 100 μm, 8 μm to 75 μm, or 10 μm to 50 μm. In one embodiment of the present invention, providing a non-woven fabric base layer with a thickness of 15 μm to 40 μm is advantageous in terms of ensuring strength and ion conductivity.

[0062] The porous structure layer 120 is filled with solid polymer particles 12 and is in a state where they are in contact with each other, and a pore structure is formed between the solid polymer particles.

[0063] At this time, the solid polymer particles can be filled and brought into contact with each other by an external pressure. For example, the external pressure can be uniaxial pressing, roll pressing, cold isostatic pressing (CIP), hot isostatic pressing (HIP), etc. However, it is not limited thereto, and physical or chemical methods capable of adhering the solid polymer particles can be used.

[0064] At this time, the solid polymer particles exceed the physical elastic region of the particles by the above-described external pressure, and the contact surface between the particles increases, the volume changes to form a new contact surface, or the adhesive force of the adhesion surface between the particles due to plastic deformation increases to form a predetermined structure. For example, the solid polymer particles can be pelletized.

[0065] The solid polymer particles are a polymer substance that is solid at normal temperature and has low solubility in the electrolyte. In the present invention, it is desirable that the solid polymer particles are surrounded by a liquid electrolyte and have low solubility in the liquid electrolyte. Further, it is desirable that the polymer has excellent chemical resistance.

[0066] Specifically, when the solid polymer particles are impregnated with a liquid electrolyte, for example, ethylene carbonate:ethyl methyl carbonate = 30:70 (volume %), they have a solubility of less than 30%. More specifically, they may have a solubility of less than 20%, less than 15% or less than 10%. Thereby, the solid polymer particles can exist in a solid state even when dispersed in a solvent.

[0067] Specifically, the solid polymer particles can be an engineering plastic resin.

[0068] At this time, the engineering plastic resin may contain any one or two or more of polyphenylene sulfide, polyether ether ketone, polyimide, polyamideimide, liquid crystal polymer, polyetherimide, polysulfone, polyarylate, polybutylene terephthalate, polyoxymethylene, polycarbonate, and polymethyl methacrylate. At this time, the engineering plastic resin may have a molecular weight of 100,000 Da to 10,000,000 Da.

[0069] Unlike general commercial inorganic particles, the solid polymer particles have compressibility. Thereby, a lithium secondary battery with an increased energy density per weight compared to the thickness can be provided. Further, by using solid polymer particles instead of conventional solid electrolytes, a deformable solid-liquid hybrid electrolyte membrane can be provided. Since such solid polymer particles have ductility, they can be physically or chemically connected by pressurization or heat. Thereby, the solid-liquid hybrid electrolyte membrane according to an embodiment of the present invention does not require a separate binder polymer. That is, the solid-liquid hybrid electrolyte membrane does not contain a binder polymer. Thereby, a solid-liquid hybrid electrolyte membrane with reduced resistance can be provided.

[0070] In a specific embodiment of the present invention, the average particle size of the solid polymer particles can be 100 nm to 10 μm, 200 nm to 5 μm, or 500 nm to 2 μm. By controlling the particle size within the above numerical range, pores of an appropriate size are formed and no short circuit occurs, and the liquid electrolyte can be sufficiently impregnated.

[0071] The present invention contains a predetermined amount of the liquid electrolyte 13, and lithium ions can be transmitted through this. That is, in one embodiment of the present invention, a lithium secondary battery including a solid-liquid hybrid electrolyte membrane with high ionic conductivity can be provided without using a solid electrolyte.

[0072] The liquid electrolyte is present at a portion where the solid polymer particles are in surface contact with each other, or surrounds the surface of the solid polymer particles. In other words, the liquid electrolyte can cover the surface of the solid polymer particles. The presence of such a liquid electrolyte can provide a solid-liquid hybrid electrolyte membrane with high ionic conductivity.

[0073] The content of the liquid electrolyte is 50 wt% to 70 wt% based on 100 wt% of the total content of the solid polymer particles and the liquid electrolyte. Specifically, the content of the liquid electrolyte can be 50 wt% or more, 55 wt% or more, or 60 wt% or more based on the total content of the solid polymer particles and the liquid electrolyte, and can be 70 wt% or less, 68 wt% or less, or 65 wt% or less of the total content of the solid polymer particles and the liquid electrolyte. Since the content of the liquid electrolyte is high in this way, the ionic conductivity of the solid-liquid hybrid electrolyte membrane can be improved.

[0074] In one embodiment of the present invention, the solid-liquid hybrid electrolyte membrane has high ionic conductivity. This is because the liquid electrolyte is uniformly dispersed and present on the surface or the surface-contact part of the solid polymer particles. In one embodiment of the present invention, in order to uniformly impregnate the liquid electrolyte in this way, one or more appropriate methods can be selected from known coating methods such as dip coating, spray coating, doctor blade coating method, or drop coating, and it is not limited to a specific method.

[0075] In a specific embodiment of the present invention, the liquid electrolyte does not dissolve the solid polymer particles and has excellent chemical resistance and electrochemical resistance.

[0076] For example, the liquid electrolyte is a salt having a structure such as A + B - wherein A + is an ion composed of an alkali metal cation such as Li + , Na + , K + or a combination thereof, and B - is PF6 - , BF4 - , Cl - , Br - , I - , ClO4 - , AsF6 - , CH3CO2 - , CF3SO3 - , N(CF3SO2)2- , a salt containing an anion such as C(CF2SO2)3 or an ion composed of a combination of these, may be dissolved or dissociated in an organic solvent such as an ether-based, carbonate-based, or nitrile-based solvent, but is not limited thereto. - For example, the ether-based organic solvent may include dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether, ethyl propyl ether, 1,2-dimethoxyethane, or a mixture of two or more of these.

[0077]

[0078] For example, the carbonate-based organic solvent may include propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), or a mixture of two or more of these.

[0079] For example, the nitrile-based organic solvent may include acetonitrile, succinonitrile, or a mixture of two or more of these.

[0080] In addition, it may include an organic solvent composed of dimethyl sulfoxide, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), γ-butyrolactone, or a mixture thereof, but is not limited thereto.

[0081] In a specific embodiment of the present invention, the ionic conductivity of the solid-phase - liquid-phase hybrid electrolyte membrane is greater than that of the porous structure layer itself, and may be 1×10 -5 ~1×10 -1 S / cm, 1×10 -4 ~1×10 -2 S / cm, or 1×10 -4 ~5×10 -3 S / cm.

[0082] ​Thus, the solid-phase - liquid-phase hybrid electrolyte membrane according to an embodiment of the present invention may have a lower porosity than the porous structure layer but may have a higher ionic conductivity than the porous structure layer itself.

[0083] In a specific embodiment of the present invention, the porous structure layer may be directly formed independently on the first electrode or the second electrode.

[0084] At this time, the forming method is not limited and may be formed by a method commonly used in the art.

[0085] For example, it can be manufactured by applying a dispersion containing solid polymer particles and a liquid electrolyte on the first electrode or the second electrode.

[0086] In an embodiment of the present invention, the solid polymer particles are present in a form in which the liquid electrolyte surrounds the solid polymer particles, so that the ionic conductivity of the solid-phase - liquid-phase hybrid electrolyte membrane can be increased in the finally manufactured lithium secondary battery.

[0087] At this time, the dispersion is overcoated on the first electrode or the second electrode to form a porous structure layer, and then a nonwoven fabric substrate is interposed, so that a nonwoven fabric substrate layer impregnated with solid polymer particles and / or a liquid electrolyte can be formed between the polymer fibrils constituting the nonwoven fabric substrate.

[0088] In a specific embodiment of the present invention, the porosity and pore size of the porous structure layer itself and the electrolyte membrane can be adjusted by controlling the average particle size of the solid polymer particles used or the pressing conditions during manufacturing. For example, it can be adjusted by adjusting the roll gap of a roll press, controlling the manufacturing temperature, or controlling the content or particle size of the solid polymer particles.

[0089] In a specific embodiment of the present invention, the thickness of the porous structure layer can be 5 μm to 500 μm, 20 μm to 300 μm, or 30 μm to 100 μm. In one embodiment of the present invention, by using a porous structure layer of a thin film such as 10 μm to 50 μm, it is advantageous in terms of energy density when manufacturing a battery later.

[0090] In a specific embodiment of the present invention, the thickness of the solid-liquid hybrid electrolyte membrane can be 5 μm to 500 μm, 20 μm to 300 μm, or 30 μm to 100 μm. In one embodiment of the present invention, a thin film-like solid-liquid hybrid electrolyte membrane such as 10 μm to 50 μm can be provided, which is advantageous in terms of energy density when manufacturing a battery later.

[0091] In a specific embodiment of the present invention, the tensile strength of the solid-liquid hybrid membrane is 500 kgf / cm 2 ~5000 kgf / cm 2 、700 kgf / cm 2 ~3000 kgf / cm 2 or 1000 kgf / cm 2 ~ about 2000 kgf / cm 2 and can be.

[0092] In a specific embodiment of the present invention, the lithium secondary battery can be a lithium-ion battery or an all-solid-state battery.

[0093] Specifically, the first electrode and the second electrode can each independently contain or not contain a solid electrolyte.

[0094] At this time, the first electrode may be a positive electrode and the second electrode may be a negative electrode, or the first electrode may be a negative electrode and the second electrode may be a positive electrode.

[0095] In the present invention, the positive electrode and the negative electrode 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 contains a plurality of electrode active material particles and may optionally contain a solid electrolyte. Further, the electrode may further contain one or more of a conductive material and a binder resin as needed. Further, the electrode may further contain various additives for the purpose of complementing or improving the physicochemical properties of the electrode.

[0096] In the present invention, the negative electrode active material can be used without limitation as long as it is a material that can be used as the negative electrode active material of a lithium-ion secondary battery. For example, the negative electrode active material may be carbon such as graphitizable carbon or graphite-based carbon; Li x Fe2O3(0 ≦ x ≦ 1), Li x WO2(0 ≦ x ≦ 1), Sn x Me 1-x Me ’ y O z (Me: Mn, Fe, Pb, Ge; Me ’ : Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen; 0 < x ≦ 1; 1 ≦ y ≦ 3; 1 ≦ z ≦ 8) and other 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 the above can be used. In a specific embodiment, the negative electrode active material may contain a carbon-based material and / or Si.

[0097] 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 may be 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-xLithium manganese oxides such as O4 (where x is from 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, Cu2V2O7; chemical formula LiNi 1-x M x Ni-site type lithium nickel oxides represented by O2 (M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, x = 0.01 to 0.3); chemical formula LiMn 1-x M x Lithium manganese composite oxides represented by O2 (M = Co, Ni, Fe, Cr, Zn or Ta, x = 0.01 to 0.1) or Li2Mn3MO8 (M = Fe, Co, Ni, Cu or Zn); LiNi x Mn 2-x Spinel-structured lithium manganese composite oxides represented by O4; LiMn2O4 in which part of the Li in the chemical formula is substituted with alkaline earth metal ions; disulfide compounds; Fe2(MoO4)3, etc., but not limited thereto.

[0098] In the present invention, as the current collector, a current collector having electrical conductivity such as a metal plate, which is known in the field of secondary batteries, can be appropriately used according to the polarity of the electrode.

[0099] In the present invention, the conductive material is usually added in an amount of 1% to 30% by weight based on the total weight of the mixture containing the electrode active material. Such a conductive material is not particularly limited as long as it has conductivity without inducing a chemical change in the battery. For example, graphite such as natural graphite and artificial graphite; carbon blacks such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, nickel powder; conductive whiskers such as zinc oxide, potassium titanate; conductive metal oxides such as titanium oxide; and one or more mixtures selected from conductive materials such as polyphenylene derivatives.

[0100] In the present invention, the binder resin is not particularly limited as long as it is a component that assists in binding the active material, conductive material, etc., and binding to the current collector. For example, 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. may be mentioned. The binder resin can usually be contained in the range of 1 to 30% by weight, or 1 to 10% by weight based on 100% by weight of the electrode layer.

[0101] On the other hand, in the present invention, the electrode active material layer may contain one or more additives such as an oxidation stability additive, a reduction stability additive, a flame retardant, a heat stabilizer, an antifogging agent, etc., as necessary.

[0102] In the present invention, the solid electrolyte may further contain one or more of a polymer solid electrolyte, an oxide solid electrolyte, and a sulfide solid electrolyte.

[0103] In the present invention, the solid electrolyte may be different for the positive electrode and the negative electrode, or the same one may be used for two or more battery elements. For example, in the case of the positive electrode, a polymer electrolyte excellent in oxidation stability may be used as the solid electrolyte. Also, in the case of the negative electrode, it is desirable to use a polymer electrolyte excellent in reduction stability as the solid electrolyte. However, it is not limited to these. Since it mainly plays a role in transmitting lithium ions at the electrode, any material with high ionic conductivity, for example, 10 -7 S / m or more or 10 -5 S / m or more can be used, and it is not limited to a specific component.

[0104] In the present invention, each of the polymer electrolytes may independently be a solid polymer electrolyte formed by adding a polymer resin to a solvated lithium salt, or a polymer gel electrolyte obtained by incorporating an organic electrolyte solution containing an organic solvent and a lithium salt into a polymer resin.

[0105] Furthermore, the present invention provides a secondary battery having the structure described above. The present invention also provides a battery module including the secondary battery as a unit cell, a battery pack including the battery module, and a device including the battery pack as a power source. At this time, specific examples of the device include power tools driven by receiving power from an electric motor; electric vehicles including electric vehicles (EV), hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), etc.; electric two-wheel vehicles including electric bicycles (E-bike) and electric scooters (E-scooter); electric golf carts; power storage systems, etc., but are not limited thereto.

[0106] One aspect of the present invention provides a method for manufacturing a lithium secondary battery according to the following embodiments. Each step is schematically shown in FIGS. 3a to 3c.

[0107] First, (S1) a dispersion liquid containing a large number of solid polymer particles and a liquid electrolyte is prepared (S1). This step is shown in FIG. 3a. At this time, as the polymer particles, solid polymer particle powder may be used. Alternatively, a dispersion liquid in which a large number of polymer particles are dispersed in a liquid electrolyte may be used. At this time, the polymer particles are as described in the solid polymer particles described above. At this time, the solvent is one that can disperse the solid polymer particles without dissolving them. For example, it may be ethanol, methanol, or the like.

[0108] On the one hand, the content of the liquid electrolyte is 50% to 70% by weight based on 100% by weight of the total content of the solid polymer particles and the liquid electrolyte. Specifically, the content of the liquid electrolyte can be 50% by weight or more, 55% by weight or more, or 60% by weight or more based on the total content of the solid polymer particles and the liquid electrolyte, and can be 70% by weight or less, 68% by weight or less, or 65% by weight or less of the total content of the solid polymer particles and the liquid electrolyte. Since the content of the liquid electrolyte is high in this way, the ionic conductivity of the solid-liquid hybrid electrolyte membrane can be improved.

[0109] In a specific embodiment of the present invention, the dispersion liquid in the step (S1) may further contain a separate solvent for dispersion. Non-limiting examples of the solvent include acetone, tetrahydrofuran, methylene chloride, etc., but are not limited thereto.

[0110] Next, the dispersion liquid is applied onto the first electrode to form a porous structure layer (S2). At this time, the first electrode can be a positive electrode or a negative electrode, and the second electrode described later is an electrode having a polarity opposite to that of the first electrode, and can be a negative electrode or a positive electrode.

[0111] At this time, the application can use a normal method available in the industry. This step is shown in FIG. 3b. As shown in FIG. 3b, in order to uniformly apply the polymer particles onto the non-woven fabric substrate 11, after dispersing the polymer particles in the liquid electrolyte, a method of coating the dispersion liquid can be used. In this case, the solid polymer particles can form a porous structure layer through a pressurization step. At this time, the solid polymer particles are those that can be physically bonded by pressurization or heat and do not require a separate binder polymer.

[0112] Also, in the case of the present invention, when forming the porous structure layer, a separate drying step is not required.

[0113] In the case of the present invention, a high-content liquid electrolyte is used to increase the ionic conductivity of the solid-liquid hybrid membrane. In order to solve the mechanical strength, morphology maintenance of the structure, and process problems caused by using a high-content liquid electrolyte, in the case of the present invention, after applying the dispersion liquid onto the electrode, a nonwoven fabric substrate is immediately interposed. Thereby, it is possible to manufacture a solid-liquid hybrid membrane that has no leakage of the liquid electrolyte and at the same time solves the above-described problems. In other words, in the case of the present invention, since the liquid electrolyte must be maintained at a high content, instead of providing a separate drying step, a step of interposing a nonwoven fabric substrate is included.

[0114] Thereafter, a solid-liquid hybrid electrolyte membrane including a nonwoven fabric substrate layer is manufactured by sequentially laminating and pressing a nonwoven fabric substrate and a second electrode having a polarity opposite to that of the first electrode on the porous structure layer (S3).

[0115] Specifically, the step S3 is a step of pressing an electrode assembly in which a first electrode, a porous structure layer, a nonwoven fabric substrate, and a second electrode are sequentially laminated after laminating the nonwoven fabric substrate on the porous structure layer. Thereby, a nonwoven fabric substrate layer in which solid polymer particles are dispersed or the liquid electrolyte is impregnated in the fine pore structure of the nonwoven fabric substrate can be formed.

[0116] At this time, the pressing step may be a step of pressing once or several times at predetermined intervals in order to control the thickness and porosity of the porous substrate layer and / or the solid-liquid hybrid electrolyte membrane.

[0117] A lithium secondary battery including a solid-liquid hybrid electrolyte membrane including a porous structure layer and a nonwoven fabric substrate layer can be manufactured by the manufacturing method.

[0118] In a specific embodiment of the present invention, the first electrode may be a positive electrode and the second electrode may be a negative electrode, or the first electrode may be a negative electrode and the second electrode may be a positive electrode.

[0119] Further, the nonwoven fabric base material layer has a fine pore structure formed by the fine structure of polymer fibrils, and solid polymer particles are dispersed in the fine pore structure or the liquid electrolyte is impregnated therein.

[0120] In a specific embodiment of the present invention, the porous structure layer is in a state where the solid polymer particles are filled and in contact with each other, and a pore structure is formed between the solid polymer particles, and the liquid electrolyte is at a portion where the solid polymer particles are in surface contact with each other or surrounds the surface of the solid polymer particles.

[0121] At this time, the nonwoven fabric base material layer may include a nonwoven fabric base material containing one or more mixtures selected from the group consisting of polyolefin, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyester, nylon, polyimide, polybenzoxazole, polytetrafluoroethylene, polyarylene ether sulfone, polyether ether ketone, and copolymers thereof.

[0122] The solid polymer particles can be an engineering plastic resin. For details, reference can be made to the above description.

[0123] The liquid electrolyte is A + B - a salt having a structure such as, A + contains ions consisting of an alkali metal cation or a combination thereof, and B - is PF6 - BF4 - Cl - Br - I - ClO4 - AsF6 - CH3CO2 - CF3SO3 - N(CF3SO2)2 - C(CF2SO2)3 - or a salt containing ions consisting of a combination thereof, but is not limited thereto.

[0124] The first electrode and the second electrode may each independently contain or not contain a solid electrolyte.

[0125] The porous structure layer may be directly coated and formed on the first electrode or the second electrode independently.

[0126] As described above, in the method for manufacturing a lithium secondary battery according to an embodiment of the present invention, a dispersion is directly applied onto an electrode. The dispersion contains solid polymer particles and a liquid electrolyte, and among these, the content of the liquid electrolyte is the same as or more than the content of the solid polymer particles. Therefore, when manufacturing a separate free-standing separator using the dispersion, there is a risk that the contained liquid electrolyte may leak, and it is difficult to maintain mechanical strength due to the high content of the liquid electrolyte. Also, when directly coating on a nonwoven fabric substrate, since the pores of the nonwoven fabric substrate are large, there is a risk that the liquid electrolyte cannot be impregnated and disappears. On the other hand, according to an embodiment of the present invention, by directly applying the dispersion onto the electrode, sufficient ionic conductivity can be ensured, short circuit can be reduced, and mechanical strength can be increased.

[0127] Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples are for illustrative purposes only and the scope of the present invention is not limited thereto.

[0128] Example 1 To prepare a slurry for forming a positive electrode, NCM811 (LiNi 0.8 Co 0.1 Mn 0.1 O2) as a positive electrode active material, VGCF (vapor grown carbon fiber) as a conductive material, and a polymer-based solid electrolyte (PEO (polyethylene oxide) + LiTFSI (lithium bis(trifluoromethane)sulfonimide), [EO] / [Li +=18:1 (molar ratio)) was produced at a weight ratio of 80:3:17. This was applied to an aluminum current collector with a thickness of 20 μm using a doctor blade, and the resulting product was vacuum dried at 120 °C for 4 hours. Thereafter, the product of the vacuum drying was subjected to a rolling process using a roll press, and based on the area of the electrode, 3 mAh / cm 2 of the positive electrode slurry was loaded to obtain a positive electrode with a porosity of 22%.

[0129] On the other hand, as the solid polymer particles, powdered polyphenylene sulfide (average particle size: 10 μm) was dispersed in a liquid electrolyte (ethylene carbonate: ethyl methyl carbonate = 3:7 (volume %), LiPF6 1 M, vinylene carbonate 0.5 volume %, fluoroethylene carbonate 1 volume %) at a ratio of 50:50 (weight ratio) to produce a dispersion liquid.

[0130] 3 ml of the above dispersion liquid was applied onto the positive electrode using a doctor blade and pressurized to form a porous structure layer. The thickness of the porous structure layer was about 94 μm. A PET non-woven fabric substrate with a thickness of 40 μm (porosity 78%) was laminated on the porous structure layer and punched into a circle with a diameter of 1.4875 cm 2 Thereafter, lithium metal was used as the negative electrode and laminated so as to face the non-woven fabric substrate, and then lamination was performed by adjusting the roll press interval at room temperature to manufacture a all-solid-state battery including a porous structure layer and a non-woven fabric substrate layer.

[0131] The thickness of the solid-liquid hybrid electrolyte membrane including the non-woven fabric substrate layer was 58 μm.

[0132] Example 2 A all-solid-state battery was manufactured in the same manner as in Example 1, except that the ratio of the solid polymer particles to the liquid electrolyte was controlled to 30:70 (weight ratio), the thickness of the porous structure layer was controlled to 81 μm, and the thickness of the solid-liquid hybrid electrolyte membrane including the non-woven fabric substrate after lamination was 50 μm.

[0133] Example 3 The ratio of the solid polymer particles to the liquid electrolyte was controlled to 30:70 (weight ratio), the thickness of the porous structure layer was controlled to 77 μm, and an all-solid-state battery was manufactured in the same manner as in Example 1, except that the thickness after lamination of the solid-liquid hybrid electrolyte membrane including a nonwoven fabric substrate layer with a thickness of 20 μm (porosity: 58%) was 43 μm.

[0134] Example 4 To prepare the slurry for forming the negative electrode, artificial graphite as the negative electrode active material, VGCF as the conductive material, and a polymer solid electrolyte (PEO + LiTFSI, [EO] / [Li + =18:1 (molar ratio)) were produced at a weight ratio of 90:2:8. This was applied to a copper current collector with a thickness of 15 μm using a doctor blade, and the resulting product was vacuum dried at 100 °C for 6 hours. Then, the resulting product of the vacuum drying was rolled using a roll press to load a negative electrode slurry of 3.3 mAh / cm 2 and a positive electrode with a porosity of 25% was obtained.

[0135] On the other hand, powdery polyphenylene sulfide (average particle size: 10 μm) as the solid polymer particles was dispersed in a liquid electrolyte (ethylene carbonate: ethyl methyl carbonate = 3:7 (volume %), 1 M LiPF6, 0.5 volume % vinylene carbonate, 1 volume % fluoroethylene carbonate) at a ratio of 30:70 (weight ratio) to produce a dispersion.

[0136] 3 ml of the dispersion was applied onto the negative electrode using a doctor blade to produce a porous structure layer. At this time, the thickness of the produced porous structure layer was about 82 μm. A PET nonwoven fabric substrate with a thickness of 40 μm (porosity 78%) was laminated on the porous structure layer, and it was punched into a circle with a diameter of 1.4875 cm 2 . Then, after laminating with lithium metal as the counter electrode so as to face the nonwoven fabric substrate, the roll press gap was adjusted at room temperature to perform lamination to manufacture an all-solid-state battery including a porous structure layer and a nonwoven fabric substrate layer.

[0137] The thickness of the solid-liquid hybrid electrolyte membrane including the nonwoven fabric substrate was 52 μm.

[0138] Example 5 A lithium-ion battery was manufactured in the following manner.

[0139] First, NCM811 (LiNi 0.8 Co 0.1 Mn 0.1 O2), VGCF as a conductive material, and polyvinylidene fluoride (PVDF) were prepared at a weight ratio of 95:3:2. This was applied to an aluminum current collector with a thickness of 20 μm using a doctor blade, and the resulting product was vacuum dried at 120 °C for 4 hours. Then, the product of the vacuum drying was rolled using a roll press to load a positive electrode slurry of 3 mAh / cm 2 to obtain a positive electrode with a porosity of 22%.

[0140] Next, powdery polyphenylene sulfide (average particle size: 10 μm) as solid polymer particles was dispersed in a liquid electrolyte (ethylene carbonate: ethyl methyl carbonate = 3:7 (volume %), LiPF6 1 M, vinylene carbonate 0.5 volume %, fluoroethylene carbonate 1 volume %) at a weight ratio of 30:70 to produce a dispersion.

[0141] 3 ml of the dispersion was applied onto the positive electrode using a doctor blade to form a porous structure layer. The thickness of the porous structure layer was about 94 μm. A PET nonwoven fabric substrate with a thickness of 40 μm (porosity 78%) was laminated on the porous structure layer and punched into a circle with a diameter of 1.4875 cm 2 . Then, lithium metal was laminated as the negative electrode so as to face the nonwoven fabric substrate, and lamination was performed by adjusting the roll press interval at room temperature to manufacture a lithium-ion battery including a porous structure layer and a nonwoven fabric substrate layer.

[0142] The thickness of the solid-phase - liquid-phase hybrid electrolyte membrane including the nonwoven fabric substrate layer was 58 μm.

[0143] Comparative Example 1 Prior to the manufacture of the all-solid-state battery, a solid-liquid hybrid electrolyte membrane was manufactured by the following method. However, since the strength of the manufactured solid-liquid electrolyte membrane was not sufficient, it was difficult to form a structure as a membrane and it could not be removed from the release film.

[0144] Powdery polyphenylene sulfide (average particle size: 10 μm) as solid polymer particles was dispersed in a liquid electrolyte (ethylene carbonate: ethyl methyl carbonate = 3:7 (volume %), LiPF6 1 M, vinylene carbonate 0.5 volume %, fluoroethylene carbonate 1 volume %) at a weight ratio of 30:70 to produce a dispersion.

[0145] 3 ml of the above dispersion was applied onto a release film using a doctor blade to fabricate a solid-liquid hybrid electrolyte membrane, rather than on an electrode. However, since the strength of the solid-liquid electrolyte membrane manufactured after coating was not sufficient, it was difficult to form a structure as a membrane and it could not be removed from the release film.

[0146] Comparative Example 2 Prior to the manufacture of the all-solid-state battery, a solid-liquid hybrid electrolyte membrane was manufactured by the following method. However, since the pores of the nonwoven fabric substrate were large, the solid polymer particles passed through the pores in the nonwoven fabric substrate and were transferred onto the other surface of the nonwoven fabric substrate or the surface became rough, making it difficult to fabricate the electrolyte membrane.

[0147] In the case of Comparative Example 2, a solid-liquid hybrid electrolyte membrane was manufactured in the same manner as in Example 2, except that the porous structure layer was directly applied onto the nonwoven fabric instead of on the electrode.

[0148] Specifically, 3 ml of the manufactured dispersion was applied onto a PET nonwoven fabric substrate with a thickness of 40 μm (porosity 78%) using a doctor blade.

[0149] In the case of Comparative Example 2, since the pores of the nonwoven fabric substrate were large, the solid polymer particles passed through the pores in the nonwoven fabric substrate and were transferred onto the other surface of the nonwoven fabric substrate or the surface became rough, making it difficult to fabricate the electrolyte membrane.

[0150] Comparative Example 3 A all-solid-state battery was manufactured in the same manner as in Example 2, except that a nonwoven fabric substrate was not used.

[0151] Specifically, 3 ml of the produced dispersion was applied onto the positive electrode using a doctor blade. At this time, the thickness of the produced porous structure layer was about 74 μm. Thereafter, after interposing the porous structure layer between the positive electrode and the lithium metal negative electrode, lamination was performed by adjusting the roll press interval at room temperature to manufacture an all-solid-state battery. The thickness of the interposed porous structure layer was 42 μm.

[0152] Comparative Example 4 A all-solid-state battery was manufactured in the same manner as in Example 2, except that a polyolefin-based separation membrane (thickness: 9 μm, porosity: 43%, pore size: 200 nm) was used instead of the nonwoven fabric substrate when manufacturing the solid-phase liquid-phase hybrid electrolyte membrane.

[0153]

Table 1

[0154] As shown in Table 1, when a dispersion containing solid polymer particles that are easily deformable is used and interposed between the positive electrode and the negative electrode together with a nonwoven fabric substrate, sufficient strength as a separation membrane can be ensured, the occurrence of micro-shorts can be reduced, and ion conductivity can be ensured.

[0155] On the other hand, in the case of Comparative Example 1 in which a nonwoven fabric substrate is not included and a solid-phase liquid-phase hybrid membrane is manufactured alone, it is difficult to manufacture a solid-phase liquid-phase hybrid membrane, and in the case of Comparative Example 3 in which a porous structure layer is directly formed on the electrode without including a nonwoven fabric substrate layer, it is difficult to fabricate a battery due to the occurrence of micro-shorts.

[0156] When directly coating the dispersion liquid on the nonwoven fabric substrate as in Comparative Example 2, since the pores of the nonwoven fabric substrate are large, the solid polymer particles or the liquid electrolyte pass through the pores in the nonwoven fabric substrate and are transferred onto the other surface of the nonwoven fabric substrate or the surface becomes rough, making it difficult to fabricate the electrolyte membrane.

[0157] Also, when applying a general polyolefin-based separation membrane instead of the nonwoven fabric substrate as in Comparative Example 4, since the porosity of the polyolefin-based separation membrane is small or the pores are small, a structure different from the structure formed between the solid polymer particles and the nonwoven fabric substrate is formed, resulting in a performance degradation due to the small pores.

Explanation of Reference Numerals

[0158] 100: Solid-Liquid Hybrid Electrolyte Membrane 110: Nonwoven Fabric Substrate Layer 120: Porous Structure Layer 11: Polymer Fibril 12: Solid Polymer Particles 13: Liquid Electrolyte 200: All-Solid-State Battery 210: Positive Electrode 220: Negative Electrode 230: Solid-Liquid Hybrid Electrolyte Membrane 231: Nonwoven Fabric Substrate Layer 232: Porous Structure Layer 21: Polymer Fibril 22: Solid Polymer Particles 23: Liquid Electrolyte

Claims

1. A lithium secondary battery including a first electrode and a second electrode having opposite polarities to each other, and a solid-liquid hybrid electrolyte membrane interposed between the first electrode and the second electrode, wherein the solid-liquid hybrid electrolyte membrane includes a nonwoven base material layer and a porous structure layer formed on at least one surface of the nonwoven base material layer. The nonwoven base material layer has a fine pore structure formed by the fine structure of polymer fibrils, and solid polymer particles are dispersed in the fine pore structure or the fine pore structure is impregnated with a liquid electrolyte, the solid-liquid hybrid electrolyte membrane does not contain a binder polymer, the porous structure layer is in a state where the solid polymer particles are filled and in contact with each other, and a pore structure is formed between the solid polymer particles. The liquid electrolyte surrounds the portion where the solid polymer particles are in surface contact with each other, or a part or the entire surface of the solid polymer particles, the content of the liquid electrolyte is 50 to 70% by weight based on 100% by weight of the total content of the solid polymer particles and the liquid electrolyte, The ionic conductivity of the solid-liquid hybrid electrolyte membrane is 1×10 －５ to 1×10 －１ S / cm, and the solid polymer particles include any one or two or more of polyphenylene oxide, polyether ether ketone, polyimide, polyamideimide, liquid crystal polymer, polyetherimide, polysulfone, polyarylate, polyethylene terephthalate, polybutylene terephthalate, polyoxymethylene, and polycarbonate, a lithium secondary battery, wherein the thickness of the porous structure layer is 30 μm to 100 μm.

2. the polymer fibrils have an average diameter of 0.005 μm to 5 μm, the nonwoven base material layer has pores with a diameter of 0.05 μm to 30 μm and a porosity in the range of 50 to 80%. The lithium secondary battery according to claim 1.

3. the polymer fibrils are one kind or a mixture of two or more kinds selected from the group consisting of polyolefin, polyethylene terephthalate, polyethylene naphthalate, polyester, nylon, polyimide, polybenzoxazole, polytetrafluoroethylene, polyarylene ether sulfone, polyether ether ketone, and copolymers thereof. The lithium secondary battery according to claim 1 or 2.

4. the solid polymer particles are engineering plastic resins. The lithium secondary battery according to any one of claims 1 to 3.

5. The thickness of the non-woven fabric base material layer is 5 μm to 100 μm, The thickness of the porous structure layer is 30 μm to 100 μm. The lithium secondary battery according to any one of claims 1 to 4.

6. The first electrode or the second electrode contains a solid electrolyte, The thickness of the solid-liquid hybrid electrolyte membrane is 43 μm to 50 μm. The lithium secondary battery according to any one of claims 1 to 5.

7. The thickness of the solid-liquid hybrid electrolyte membrane is 43 μm to 100 μm. The lithium secondary battery according to any one of claims 1 to 4.

8. The lithium secondary battery is a lithium-ion secondary battery or an all-solid-state battery. The lithium secondary battery according to any one of claims 1 to 7.

9. The first electrode and the second electrode each independently contain a solid electrolyte or do not contain it. The lithium secondary battery according to any one of claims 1 to 8.

10. The porous structure layer is directly coated and formed on the first electrode or the second electrode independently. The lithium secondary battery according to any one of claims 1 to 9.

11. A method for manufacturing a lithium secondary battery including a first electrode and a second electrode having opposite polarities to each other, and a solid-liquid hybrid electrolyte membrane interposed between the first electrode and the second electrode, (S1) preparing a dispersion containing solid polymer particles and a liquid electrolyte; (S2) coating the dispersion on the first electrode to form a porous structure layer; (S3) sequentially laminating and pressing a non-woven fabric base material and a second electrode having a polarity opposite to that of the first electrode on the porous structure layer to manufacture a solid-liquid hybrid electrolyte membrane including a non-woven fabric base material layer. The content of the liquid electrolyte is 50% to 70% based on 100% by weight of the total content of the solid-liquid hybrid electrolyte membrane. A method for manufacturing a lithium secondary battery.

12. The first electrode is a positive electrode and the second electrode is a negative electrode, or The first electrode is a negative electrode and the second electrode is a positive electrode. The method for manufacturing a lithium secondary battery according to claim 11.

13. The non-woven fabric base material layer has a fine pore structure formed by the fine structure of polymer fibrils, and solid polymer particles are dispersed in the fine pore structure or the liquid electrolyte is impregnated therein. The porous structure layer is in a state where the solid polymer particles are filled and in contact with each other, a pore structure is formed between the solid polymer particles, and the liquid electrolyte is at a portion where the solid polymer particles are in surface contact with each other or surrounds the surface of the solid polymer particles. The method for manufacturing a lithium secondary battery according to claim 11 or 12.

14. The nonwoven fabric base material layer contains one or a mixture of two or more selected from the group consisting of polyolefin, polyethylene terephthalate, polyethylene naphthalate, polyester, nylon, polyimide, polybenzoxazole, polytetrafluoroethylene, polyarylene ether sulfone, polyether ether ketone, and copolymers thereof. The method for manufacturing a lithium secondary battery according to any one of claims 11 to 13.

15. The solid polymer particles are engineering plastic resins. The method for manufacturing a lithium secondary battery according to any one of claims 11 to 14.

16. The liquid electrolyte is a salt having a structure such as A ＋ B － wherein A ＋ contains ions composed of alkali metal cations or combinations thereof, and B － is PF ６ － , BF ４ － , Cl － , Br － , I － , ClO ４ － , AsF ６ － , CH ３ CO ２ － , CF ３ SO ３ － , N(CF ３ SO ２ ) ２ － , C(CF ２ SO ２ ) ３ － The method for manufacturing a lithium secondary battery according to any one of claims 11 to 15, which is a salt containing ions composed of or combinations thereof.

17. The lithium secondary battery is a lithium ion secondary battery or an all-solid-state battery. The method for manufacturing a lithium secondary battery according to any one of claims 11 to 16.

18. The first electrode and the second electrode each independently contain or do not contain a solid electrolyte. The method for manufacturing a lithium secondary battery according to any one of claims 11 to 17.

19. A lithium secondary battery including a first electrode and a second electrode having opposite polarities to each other, and a solid-phase - liquid-phase hybrid electrolyte membrane interposed between the first electrode and the second electrode, wherein the solid-phase - liquid-phase hybrid electrolyte membrane includes a nonwoven fabric base material layer and a porous structure layer formed on at least one surface of the nonwoven fabric base material layer. The nonwoven fabric base material layer has a fine pore structure formed by a fine structure of polymer fibrils, and solid polymer particles are dispersed in the fine pore structure or the fine pore structure is impregnated with a liquid electrolyte. The solid-phase - liquid-phase hybrid electrolyte membrane does not contain a binder polymer. The porous structure layer is in a state where the solid polymer particles are filled and in contact with each other, a pore structure is formed between the solid polymer particles, and the liquid electrolyte is at a portion where the solid polymer particles are in surface contact with each other, or surrounds a part or the entire surface of the solid polymer particles. The content of the liquid electrolyte is 50 to 70% by weight based on 100% by weight of the total content of the solid polymer particles and the liquid electrolyte, The ionic conductivity of the solid-liquid hybrid electrolyte membrane is 1×10 －５ to 1×10 －１ S / cm, and A lithium secondary battery in which the solid polymer particles are made of polyphenylene sulfide.

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