COF film solid electrolyte, manufacturing method thereof, and lithium secondary battery comprising same

Abstract

The present invention relates to: a solid electrolyte for a lithium secondary battery; and a lithium secondary battery comprising same, the solid electrolyte comprising a covalent organic framework (COF) film solid electrolyte represented by chemical formula 1, having unit structures linked by a beta ketoenamine functional group, and comprising a lithium sulfonate functional group.

Description

COF film solid electrolyte, method for producing the same, and lithium secondary battery comprising the same

[0001] Cross-citation with related application(s)

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0167277, filed November 27, 2023, and Korean Patent Application No. 10-2024-0149966, filed October 29, 2024, the entire contents of which are incorporated herein by reference.

[0003] The present invention relates to a COF film solid electrolyte, a method for producing the same, and a lithium secondary battery including the same.

[0004] Due to the rapid increase in fossil fuel use, the demand for alternative or clean energy is increasing, and as part of this, the field of most active research is the field of power generation and storage using electrochemistry.

[0005] A representative example of an electrochemical device that currently utilizes this electrochemical energy is the secondary battery, and its application area is gradually expanding.

[0006] Recently, with the increase in technological development and demand for portable devices such as portable computers, mobile phones, and cameras, the demand for secondary batteries as an energy source has been rapidly increasing. Among such secondary batteries, much research has been conducted on lithium secondary batteries that exhibit high charge / discharge characteristics and lifespan characteristics and are environmentally friendly, and they have been commercialized and widely used.

[0007] Typically, lithium secondary batteries are structured to have an electrode assembly comprising a positive electrode, a negative electrode, and a porous separator, each impregnated with a non-aqueous electrolyte. Furthermore, the positive electrode is typically manufactured by coating a positive electrode mixture containing a positive electrode active material onto aluminum foil, while the negative electrode is typically manufactured by coating a negative electrode mixture containing a negative electrode active material onto copper foil.

[0008] Typically, the positive electrode active material is a lithium transition metal oxide, and the negative electrode active material is a carbon-based material.

[0009] However, recently, lithium metal batteries that use lithium metal itself, which exhibits high energy density, as the negative electrode active material have been commercialized.

[0010] At this time, the lithium metal used as the negative electrode has a density (0.54 g / cm 3 ) and a very low standard reduction potential (-3.045 V SHE), making it the most sought-after material as an anode material for high-energy-density batteries. In addition, despite the problems arising from its very high chemical activity, the need for the development of high-energy-density secondary batteries continues to grow due to the continuous increase and rapid development of mobile communication and portable electronic devices, and thus the need for the use of lithium metal anodes continues to arise.

[0011] However, the liquid electrolyte used in lithium metal batteries using these lithium metal cathodes is problematic in terms of safety because it uses highly flammable and combustible organic solvents.

[0012] Therefore, research is being conducted on solid electrolytes with high safety, but solid electrolytes have limitations in that they have low ionic conductivity and have a rough surface that makes it difficult to make contact with the electrode.

[0013] Accordingly, there is an urgent need to develop technology for solid electrolytes for lithium secondary batteries that can improve both ionic conductivity and interfacial resistance, which are identified as problems with existing solid electrolytes.

[0014] Accordingly, the present invention relates to a COF film solid electrolyte having high ionic conductivity and single conductivity while reducing interfacial resistance with an electrode, a method for producing the same, and a lithium secondary battery including the same.

[0015] Accordingly, the present invention provides a COF (covalent organic framework) film solid electrolyte having a unit structure represented by the following chemical formula 1 and connected with a beta-ketoenamine functional group, and including a lithium sulfonate functional group.

[0016] [Chemical Formula 1]

[0017]

[0018] Here, the COF (covalent organic framework) film solid electrolyte may be a polymer of a lithium salt, a 3,3-disulfobenzidine monomer, and a 1,3,5-triformylphloroglucinol monomer.

[0019] The above COF film solid electrolyte may have uniform pores, each of which may have a pore diameter in the range of 1.5 nm to 2.5 nm, and the difference between each pore diameter is 0.1 μm or less. In addition, the interlayer spacing of the COF film solid electrolyte may be 0.3 nm to 0.4 nm.

[0020] The thickness of the above COF film solid electrolyte may be 1 to 60 μm.

[0021] The specific surface area of ​​the above COF film solid electrolyte is 250 m 2 / g to 300m 2 / g, and the surface roughness (Ra) of the COF film solid electrolyte may be 1 nm to 30 nm, and the interfacial resistance of the COF film solid electrolyte with the Li electrode may be 100Ω to 1000Ω.

[0022] The present invention also provides a method for manufacturing the COF film solid electrolyte,

[0023] A method for manufacturing a COF film solid electrolyte is provided, which synthesizes a COF film by reacting a lithium salt, an amine monomer, and an aldehyde monomer in a molar ratio of 3:2 in a DMSO (dimethyl sulfoxide) solvent.

[0024] Here, the amine monomer may be represented by the following chemical formula 2.

[0025] [Chemical Formula 2]

[0026]

[0027] Additionally, the aldehyde monomer may be represented by the following chemical formula 3.

[0028] [Chemical Formula 3]

[0029]

[0030] Specifically, the method for manufacturing the COF film solid electrolyte is as follows:

[0031] (a) Mixing the lithium salt and the amine monomer under a DMSO solvent, and mixing the aldehyde monomer under a DMSO solvent to prepare pre-solutions 1 and 2, respectively,

[0032] (b) Mix the above solvents 1 and 2 and polymerize them,

[0033] (c) crystallizing the polymerized solution,

[0034] (d) It may include a process of coating and drying the above crystallized solution in the form of a film.

[0035] The molar concentration of the amine monomer in the above pre-solution 1 may be 0.01 mmol / mL to 0.05 mmol / mL, and the molar concentration of the aldehyde monomer in the above pre-solution 2 may be 0.067 mmol / mL to 0.033 mmol / mL.

[0036] The above crystallization can be performed by leaving the above polymerized solution at 20 to 30 degrees Celsius for 20 to 30 hours.

[0037] The above drying can be performed at 50 to 80 degrees Celsius for 5 to 10 days.

[0038] Furthermore, the present invention provides a lithium secondary battery including the COF film solid electrolyte, comprising a positive electrode, a negative electrode, and a COF film solid electrolyte interposed between the positive electrode and the negative electrode.

[0039] Here, the positive electrode may specifically include lithium iron phosphate as a positive electrode active material, and the negative electrode may specifically include lithium metal as a negative electrode active material.

[0040] Here, the thickness of the COF film solid electrolyte may be 1 μm to 60 μm.

[0041] Additionally, the lithium secondary battery may further include a separator between the positive electrode and the negative electrode.

[0042] FIG. 1 is a schematic diagram showing a simulation structure of a COF film solid electrolyte according to one embodiment of the present invention.

[0043] FIG. 2 is a schematic diagram illustrating a method for manufacturing a COF film solid electrolyte according to one embodiment of the present invention.

[0044] Figure 3 is a graph showing the thickness increase according to the molar ratio of the amine monomer according to Experimental Example 1.

[0045] Figures 4 and 5 are cross-sectional views and plan views of a COF film solid electrolyte according to Experimental Example 1.

[0046] Figure 6 is an FT-IR spectrum of a COF film solid electrolyte according to Experimental Example 2.

[0047] Figure 7 is an XRD graph of a COF film solid electrolyte according to Experimental Example 2.

[0048] Figure 8 is a graph of nitrogen adsorption / desorption curves and pore distribution of a COF film solid electrolyte according to Experimental Example 3.

[0049] Figure 9 is a TEM photograph of a COF film solid electrolyte according to Experimental Example 3.

[0050] Figure 10 is a graph of the ionic conductivity and ionic conductivity of a solid electrolyte according to Experimental Example 4.

[0051] Figure 11 is a graph of the interfacial resistance of a solid electrolyte with an electrode according to Experimental Example 5.

[0052] Figure 12 is a graph evaluating the oxidation stability of a solid electrolyte according to Experimental Example 6.

[0053] Figures 13 and 14 are overvoltage evaluation graphs according to Experimental Example 7.

[0054] Figure 15 is a life evaluation graph according to Experimental Example 8.

[0055] Figure 16 is a graph showing the capacity change and efficiency according to the cycle at each current density depending on the thickness of the COF film solid electrolyte according to Experimental Example 9.

[0056] Figures 17 and 18 show the results of evaluating cycle characteristics according to Experimental Example 10.

[0057] Hereinafter, electrolytes for lithium metal batteries according to specific implementation examples of the invention will be described.

[0058] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0059] The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

[0060] In this specification, it should be understood that the terms “include,” “comprising,” or “having” are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0061] In this specification, “cross-section” means a plane cut perpendicular to the thickness direction, and “plane” means a plane viewed from the top of the widest surface of an object.

[0062]

[0063] According to one embodiment of the invention, a COF (covalent organic framework) film solid electrolyte is provided, which is represented by the following chemical formula 1, has a unit structure linked by a beta-ketoenamine functional group, and includes a lithium sulfonate functional group.

[0064] [Chemical Formula 1]

[0065]

[0066] The above COF (covalent organic framework) film solid electrolyte may be a polymer of a lithium salt, a 3,3-disulfobenzidine monomer, and a 1,3,5-triformylphloroglucinol monomer.

[0067] Here, the 3,3-disulfobenzidine monomer may be represented by the following chemical formula 2.

[0068] [Chemical Formula 2]

[0069]

[0070] The above 1, 3, 5-triformylphloroglucinol monomer may be represented by the following chemical formula 3.

[0071] [Chemical Formula 3]

[0072]

[0073] A solid electrolyte represented by the chemical formula 1 is manufactured by polymerizing the above monomers and lithium salt.

[0074] The simulation structure of such a COF film solid electrolyte is shown in Fig. 1 below.

[0075] Referring to FIG. 1, the COF film solid electrolyte may be one in which hexagonal pores are continuously formed in a plate shape by the polymerization.

[0076] Here, the pores may each have a pore diameter (R) within a range of 1.5 nm to 2.5 nm, specifically within a range of 1.8 nm to 2.3 nm, and more specifically within a range of 2.0 nm to 2.2 nm.

[0077] Additionally, the above pores may have uniform pores with a difference in each pore diameter of 0.1 nm or less.

[0078] Furthermore, the interlayer spacing of the COF film solid electrolyte may be 0.3 nm to 0.4 nm, specifically 0.3 nm to 0.35 nm, and more specifically 0.32 nm to 0.35 nm.

[0079] Moreover, the specific surface area of ​​the COF film solid electrolyte is 250 m 2 / g to 300m2 / g can be, and in detail 260m 2 / g to 290m 2 / g can be, more specifically, 270m 2 / g to 290m 2 / g may be.

[0080] Additionally, the surface roughness (Rz) of the COF film solid electrolyte may be 1 nm to 30 nm, and specifically 3 nm to 25 nm.

[0081] Here, the pore diameter and specific surface area can be confirmed by measuring the pore distribution using a nitrogen adsorption / desorption method.

[0082] Specifically, about 0.03 mg of the obtained COF film solid electrolyte sample is prepared and dried at 120 degrees Celsius for 12 hours to remove internal moisture, and then the specific surface area can be measured under the conditions of an absolute temperature of 77 K in a liquid nitrogen environment. In addition, the nitrogen adsorption / desorption curve obtained at this time can be used to obtain a pore distribution map through the Non Local Density Functional Theory (NLDFT) method, and the pore diameter can be determined through this pore distribution map.

[0083] Additionally, the interlayer spacing can be calculated by taking a TEM image of the COF film solid electrolyte.

[0084] Specifically, using TEM equipment with a voltage of 300 kV, an image can be obtained that can observe materials of 10 nm or less with a resolution of 200 k or more, and the spacing between lattices shown in the image can be directly measured, or the lattice spacing can be measured by converting the obtained TEM image into a Fast Fourier Transform (FFT) image.

[0085] Moreover, the surface roughness (Rz) can be measured using an optical measuring instrument (Agilent 5500 SPM from Agilent), and the surface of the sample is photographed in an enlarged manner, and then the difference in height between the highest peak and the lowest peak within the travel distance is calculated to calculate the surface roughness (Rz) of the electrode.

[0086] Meanwhile, from the numerical values ​​obtained above, it can be seen that the COF film solid electrolyte according to the present invention can have high crystallinity, high ionic conductivity due to ion channels with little curvature, and a smooth surface with very little surface roughness, so that not only can the contact with the electrode be increased to significantly reduce the interfacial resistance, but also oxidation stability can be improved.

[0087] The thickness of the above COF film solid electrolyte may be 1 µm to 60 µm, specifically 5 µm to 50 µm, and more specifically 15 µm to 40 µm.

[0088] Forming it with a thickness that is too thin without satisfying the above range is not only difficult in terms of process, but also cannot sufficiently function as a solid electrolyte when applied to a lithium secondary battery, and when interposed between the positive and negative electrodes in place of a separator, its strength is weak and a short circuit problem may occur, which is not desirable.

[0089] On the other hand, if it is too large, there is a problem that the crystallinity decreases due to the increase in thickness, which reduces the ionic conductivity and increases the surface roughness, thereby increasing the interfacial resistance with the electrode.

[0090] The COF film solid electrolyte as described above may have an interface resistance with the Li electrode of 100Ω to 1000Ω, specifically, 200Ω to 800Ω, and more specifically, 300Ω to 700Ω.

[0091] Beyond the above range, if the interfacial resistance is too high, there is a problem that the capacity rapidly decreases at high current density and the life characteristics and output characteristics deteriorate in a lithium secondary battery using lithium metal as an anode.

[0092] Meanwhile, according to another embodiment of the present invention, a method for manufacturing the COF film solid electrolyte is provided, and specifically, the method comprises synthesizing a COF film by reacting a lithium salt, an amine monomer, and an aldehyde monomer in a molar ratio of 3:2 in a DMSO solvent.

[0093] Here, the amine monomer may be a 3,3-disulfobenzidine monomer represented by the following chemical formula 2, and the aldehyde monomer may be a 1,3,5-triformylphloroglucinol monomer represented by the following chemical formula 3.

[0094] [Chemical Formula 2]

[0095]

[0096] [Chemical Formula 3]

[0097]

[0098] More specifically, FIG. 2 schematically illustrates a method for synthesizing such a COF film.

[0099] Referring to FIG. 2, the COF film solid electrolyte according to the present invention is

[0100] (a) Mixing the lithium salt and the amine monomer under a DMSO solvent, and mixing the aldehyde monomer under a DMSO solvent to prepare pre-solutions 1 and 2, respectively,

[0101] (b) Mix the above solvents 1 and 2 and polymerize them,

[0102] (c) crystallizing the polymerized solution,

[0103] (d) It can be manufactured by including a process of coating and drying the above crystallized solution in a film form.

[0104] By this manufacturing method, the amine monomer and lithium salt first react to form an amine monomer in the form of a lithium salt.

[0105] Thereafter, the amine group of the amine monomer and the aldehyde group of the aldehyde monomer react and polymerize to produce a COF film solid electrolyte having a specific organic skeletal structure.

[0106] Here, the amine monomer and lithium salt react at a molar ratio of 1:2, and therefore, the lithium salt, amine monomer, and aldehyde monomer can react at a molar ratio of 6:3:2.

[0107] Meanwhile, the inventors of the present application confirmed that the thickness and electrochemical performance of the COF film solid electrolyte manufactured in this manner vary depending on the molar concentration of the monomers, and accordingly, in order to manufacture the film with a thin thickness as described above and sufficiently improve the ion conductivity, specifically, the molar concentration of the amine monomer in the pre-solution 1 may be 0.01 mmol / mL to 0.10 mmol / mL, specifically, 0.01 mmol / mL to 0.01 mmol / mL. In addition, the molar concentration of the aldehyde monomer in the pre-solution 2 may be 0.0067 mmol / mL to 0.0667 mmol / mL, specifically, 0.0067 mmol / mL to 0.033 mmol / mL.

[0108] In addition, after polymerization of the amine monomer and the aldehyde monomer, a crystallization process is performed to ensure complete crystallization. The crystallization process can be performed by leaving the polymerized solution for a certain period of time, and specifically, the crystallization process can be performed by leaving the polymerized solution at 20 to 30 degrees Celsius for 20 to 30 hours, and more specifically, the crystallization process can be performed by leaving the solution at 24 to 26 degrees Celsius for 24 to 28 hours.

[0109] Additionally, the process of coating and drying the crystallized solution in the form of a film can be performed by coating the crystallized solution on a substrate and drying it.

[0110] Here, a glass substrate or the like can be used as the substrate, and at this time, the COF film solid electrolyte can be obtained by coating the glass substrate, drying it, and then removing the glass substrate. Alternatively, a positive electrode or negative electrode can be used as the substrate to subsequently include the COF film solid electrolyte in a lithium secondary battery.

[0111] The above coating can be determined by considering the thickness of the COF film to be obtained, and can be coated so as to obtain a COF film having a thickness of 1 μm to 60 μm as described above.

[0112] After coating on the above substrate in this way, a drying process is performed.

[0113] At this time, the drying may be performed at 50 to 80 degrees Celsius for 5 to 10 days, and more specifically, may be performed at 60 to 70 degrees Celsius for 6 to 8 days.

[0114] If the process is performed at a temperature that is too low outside the above range, sufficient drying may not occur or the drying period may be prolonged, resulting in a decrease in process efficiency. If the process is performed at a temperature that is too high, the structure of the polymer represented by the above chemical formula 1 forming the COF film may be affected, and the process may be dried unevenly, increasing the roughness of the film surface and increasing the interfacial resistance with the electrode, which is undesirable.

[0115] Similarly, performing the process for too short a time may not result in sufficient drying, and performing the process for too long may result in lower process efficiency, which is not desirable.

[0116] The COF film solid electrolyte according to the present invention manufactured in this manner can be interposed with a thin thickness to increase ionic conductivity while significantly reducing interfacial resistance with a Li electrode, so that a lithium secondary battery including the same can exhibit excellent electrochemical performance.

[0117] Therefore, according to another embodiment of the present invention, a lithium secondary battery including the COF film solid electrolyte is provided, the lithium secondary battery including a positive electrode, a negative electrode, and a COF film solid electrolyte interposed between the positive electrode and the negative electrode.

[0118] Specifically, the positive electrode may have a structure including a positive electrode current collector and a positive electrode active material layer formed on one or both sides of the positive electrode current collector.

[0119] Here, the positive electrode current collector may be any conductive material that does not induce chemical changes in the battery, and is not particularly limited. For example, the current collector may be made of stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, or the like.

[0120] The above-mentioned positive electrode current collector may have a thickness of 3 μm to 500 μm, and fine unevenness may be formed on the surface of the positive electrode current collector to increase adhesion to the positive electrode active material layer. For example, it may be used in various forms such as a film, sheet, foil, net, porous body, foam, or non-woven fabric.

[0121] The above positive electrode active material layer includes a positive electrode active material and may include a conductive agent, a binder, and other additives as needed.

[0122] The above positive electrode active material is not limited to a compound capable of reversible intercalation and deintercalation of lithium, but specifically may be a lithium transition metal oxide or a lithium iron phosphate, and in addition, the above positive electrode active material may be a lithium transition metal oxide, such as a lithium-manganese oxide (e.g., LiMnO2, LiMn2O4, etc.), a lithium-cobalt oxide (e.g., LiCoO2, etc.), a lithium-nickel oxide (e.g., LiNiO2, etc.), a lithium-nickel-manganese oxide (e.g., Li 1+x’ Ni 1-Y Mn Y O2(where, -0.5≤x'≤0.5, 0 <Y<1), Li 1+x’’ Mn 2-Z Ni Z O4 (where -0.5≤x''≤0.5, 0<Z<2), etc.), lithium-nickel-cobalt oxides (e.g., Li 1+x’’’ Ni 1-Y1 Co Y1 O2(here, -0.5≤x'''≤0.5, 0 <Y1<1) 등), 리튬-망간-코발트계 산화물(예를 들면, Li 1+x’’’’ Co 1-Y2 Mn Y2 O2(here, -0.5≤x''''≤0.5, 0 <Y2<1), Li 1+x’’’’’ Mn 2-Z1 Co Z1 O4 (where -0.5≤x'''''≤0.5, 0<Z1<2), etc.), lithium-nickel-manganese-cobalt oxides (e.g., Li 1+a1 (Nip Co q Mn r )O2(where, -0.5≤a1≤0.5, 0<p<1, 0<q<1, 0<r<1, p+q+r=1) or Li 1+a2 (Ni p1 Co q1 Mn r1 )O4 (wherein, -0.5≤a2≤0.5, 0<p1<2, 0<q1<2, 0<r1<2, p1+q1+r1=2) etc.), or lithium-nickel-cobalt-transition metal (M) oxide (e.g., Li 1+a3 (Ni p2 Co q2 Mn r2 M s2 )O2 (wherein, M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg and Mo, and a3, p2, q2, r2 and s2 are atomic fractions of independent elements, respectively, -0.5≤a3≤0.5, 0<p2<1, 0<q2<1, 0<r2<1, 0<s2<1, p2+q2+r2+s2=1), etc.), lithium iron phosphate (e.g., Li 1+a4 Fe 1-p3 M p3 (PO 4-b4 )X b4 (Here, M is at least one selected from Al, Mg, and Ti, X is at least one selected from F, S, and N, -0.5≤a4≤0.5, 0≤p3≤0.5, 0≤b4≤0.1) and the like, and any one or two or more compounds thereof may be included, but most specifically, lithium iron phosphate may be included.

[0123] The above positive electrode active material may be included in an amount of 60 to 98 wt%, preferably 80 to 98 wt%, and more preferably 90 to 98 wt%, based on the total weight of the positive electrode active material layer.

[0124] The conductive agent is a component for further improving the conductivity of the positive electrode active material, and the conductive agent is not particularly limited as long as it has conductivity without causing a chemical change in the battery, and for example, carbon powder such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal black; graphite powder such as natural graphite, artificial graphite, or graphite with a highly developed crystal structure; conductive fibers such as carbon fibers or metal fibers; fluorinated carbon powder; conductive powder such as aluminum powder or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives, etc. can be used.

[0125] The above-mentioned conductive material may be included in an amount of 0.1 to 20 wt%, specifically 0.5 to 10 wt%, and more specifically 0.5 to 5 wt%, based on the total weight of the positive electrode active material layer.

[0126] The above binder is a component that assists in bonding between the conductive material, the positive electrode active material, and the positive electrode current collector. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polyethylene, polypropylene, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber, fluororubber, and various copolymers thereof.

[0127] Typically, the binder may be included in an amount of 0.5 to 20 wt%, specifically 0.5 to 10 wt%, and more specifically 0.5 to 5 wt%, based on the total weight of the positive electrode active material layer.

[0128] In addition, the above-mentioned other additives may further include, for example, fillers as components that suppress expansion. The fillers are not particularly limited as long as they can suppress expansion of the electrode without causing chemical changes in the battery, and examples thereof include olefin polymers such as polyethylene and polypropylene; fibrous materials such as glass fiber and carbon fiber; and the like.

[0129] The above negative electrode has a structure in which a negative electrode active material layer is formed on one or both sides of the negative electrode current collector, similar to the above positive electrode.

[0130] The above negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used.

[0131] The above-mentioned negative electrode collector may typically have a thickness of 3 μm to 500 μm, and like the positive electrode collector, it may be provided with fine irregularities on the surface of the negative electrode collector to enhance the bonding strength of the negative electrode active material. For example, it may be used in various forms such as a film, sheet, foil, net, porous body, foam, or non-woven fabric.

[0132] The above negative active material may include a conductive material, a binder, and other additives as described above together with the negative active material.

[0133] The above negative active material is at least one carbon-based material selected from the group consisting of graphite, amorphous hard carbon, low-crystalline soft carbon, carbon black, acetylene black, Ketjen black, super P, graphene, and fibrous carbon, Si-based material, Li x Fe2O3(0≤x≤1), Li x WO2(0≤x≤1), Sn xMe 1-x Me' y O z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, elements of group 1, 2, and 3 of the periodic table, halogens; 0 <x≤1; 1≤y≤3; 1≤z≤8) 등의 금속 복합 산화물; 리튬 금속; 리튬 합금; 규소계 합금; 주석계 합금; SiO, SiO2, SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, and Bi2O5등의 금속 산화물; 폴리아세틸렌 등의 도전성 고분자; Li-Co-Ni 계 재료; 티타늄 산화물; 리튬 티타늄 산화물 등을 더 포함할 수 있지만, 당업계에 알려진 것이라면 이들만으로 한정되는 것은 아니다.

[0134] The above negative electrode active material may be included in an amount of 60 to 98 wt%, preferably 80 to 98 wt%, and more preferably 90 to 98 wt%, based on the total weight of the negative electrode active material layer.

[0135] Specifically, the negative electrode may include lithium metal as an active material. More specifically, the negative electrode may be formed of a lithium metal layer, or may have a structure in which a lithium metal layer is formed on one or both sides of a separate negative electrode current collector.

[0136] The negative electrode formed of the lithium metal layer may be formed of lithium metal itself without a separate negative electrode current collector. Accordingly, in this case, the lithium metal layer may have a sufficient thickness, for example, a thickness of 10 μm to 300 μm.

[0137] Alternatively, the lithium metal layer may be formed by physically bonding, rolling, or depositing lithium metal on the negative electrode current collector. The deposition method may use an electrical deposition method or a chemical vapor deposition method.

[0138] Here, the lithium metal layer can be formed to a total thickness of 10 to 300 μm so that it can sufficiently function as a negative electrode active material.

[0139] The lithium metal layer may include an alloy that partially contains, in addition to lithium (Li), one type of metal selected from the group consisting of nickel (Ni), tin (Sn), copper (Cu), and indium (In).

[0140] The thickness of the COF film solid electrolyte interposed between the positive electrode and the negative electrode may be 1 µm to 60 µm, specifically, 5 µm to 50 µm, and more specifically, 15 µm to 40 µm. The reason for this is as described above.

[0141] Such COF film solid electrolyte may be formed as a separate film and interposed separately between the anode and cathode, or may be interposed in the form of transferring the COF film solid electrolyte formed on a substrate onto the anode or cathode and laminating another electrode.

[0142] At this time, the COF film solid electrolyte can be mainly transferred to the anode.

[0143] Alternatively, the COF film solid electrolyte may be formed by directly coating and drying a solution for forming the COF film solid electrolyte using the positive or negative electrode as a substrate. In this case, it may also be formed primarily on the positive electrode.

[0144] Meanwhile, it is most preferable in terms of ionic conductivity or interface resistance that the COF film solid electrolyte performs both the role of an electrolyte and a separator and does not include a separate separator. However, as an example, the lithium secondary battery may further include a separator in addition to the COF film solid electrolyte between the positive electrode and the negative electrode.

[0145] The above separator can be used without any special restrictions as long as it is commonly used as a separator in a lithium secondary battery, and it is particularly preferable that it has low resistance to ion movement of the electrolyte and excellent electrolyte moisture retention capacity.

[0146] For example, as a separator, a porous polymer film including a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof can be used. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc., can also be used as a separator.

[0147] Alternatively, it may be a Safety Reinforced Separator (SRS) membrane in which a coating layer including a binder and inorganic particles is formed on one or both sides of a polymer substrate as described above.

[0148] The SRS separator is as described above. Specifically, the polyolefin substrate of the SRS separator is as described above, and the coating layer includes inorganic particles and a binder.

[0149] Here, the inorganic particles play a dual role: they form micropores by allowing the formation of empty spaces between the inorganic particles, and they also serve as a type of spacer that maintains their physical form. Furthermore, since the inorganic particles generally have a property of not changing their physical properties even at temperatures exceeding 200°C, the formed organic-inorganic mixed layer possesses excellent heat resistance.

[0150] The inorganic particles described above are not particularly limited as long as they are electrochemically stable. That is, the inorganic particles that can be used in the present invention are not particularly limited as long as they do not undergo oxidation and / or reduction reactions within the operating voltage range of the battery to which they are applied. In particular, when using inorganic particles with ion transfer capabilities, it is preferable to use particles with as high an ion conductivity as possible, as this can enhance performance by increasing the ionic conductivity within the electrochemical device. In addition, when the inorganic particles have a high density, it is difficult to disperse them during manufacturing, and there is also the problem of weight increase during the manufacturing of the secondary battery, so it is preferable to use particles with as low a density as possible. In addition, when using inorganic particles with a high dielectric constant, they can contribute to an increase in the dissociation of electrolyte salts, such as lithium salts, in the liquid electrolyte, thereby improving the ionic conductivity of the electrolyte. Finally, inorganic particles with thermal conductivity are even more preferable, as they have excellent heat absorption capabilities, which prevents heat from being concentrated locally, forming a heating point and leading to thermal runaway.

[0151] For the reasons mentioned above, the inorganic particles are preferably at least one selected from the group consisting of (a) high-dielectric constant inorganic particles having a dielectric constant of 1 or more, 5 or more, preferably 10 or more, (b) inorganic particles having piezoelectricity, (c) thermally conductive inorganic particles, and (d) inorganic particles having lithium ion transfer capability.

[0152] The above piezoelectric inorganic particles are non-conductive at normal pressure, but when a certain pressure is applied, they are materials that have the property of conducting electricity due to a change in their internal structure. In addition, when a certain pressure is applied and they are stretched or compressed, they generate electric charges, so that one side is charged positively and the other side is charged negatively, and they are materials that have the function of generating a potential difference between the two sides.

[0153] Examples of the above piezoelectric inorganic particles include BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT), PB(Mg3Nb 2 / 3 )O3-PbTiO3(PMN-PT) hafnia (H f O2) or mixtures thereof, but are not limited thereto.

[0154] The above inorganic particles having lithium ion transfer capability refer to inorganic particles that contain lithium elements but do not store lithium and have the function of transferring lithium ions. Since the inorganic particles having lithium ion transfer capability can transfer and move lithium ions due to a type of defect existing within the particle structure, they can prevent a decrease in lithium mobility and thus a decrease in battery capacity.

[0155] Examples of inorganic particles having the above lithium ion transfer capability include lithium phosphate (Li3PO4), lithium titanium phosphate (Li x Ti y (PO4)3, 0 <x<2, 0<y<3), 리튬알루미늄티타늄포스페이트(Li x Al y Ti z (PO4)3, 0 <x<2, 0<y<1, 0<z<3), 14Li2O-9Al2O3-38TiO2-39P2O5등과 같은 (LiAlTiP) x O y Series glass (0 <x<4, 0<y<13), 리튬란탄티타네이트(Li x La y TiO3, 0 <x<2, 0<y<3), Li 3.25 Ge 0.25 P 0.75 Lithium germanium thiophosphate (Li) such as S4 x Ge y P z S w, 0 <x<4, 0<y<1, 0<z<1, 0<w<5), Li3N 등과 같은 리튬나이트라이드(Li x N y , 0 <x<4, 0<y<2), Li3PO4-Li2S-SiS2등과 같은 SiS2계열 glass (Li x Si y S z , 0 <x<3, 0<y<2, 0<z<4), LiI-Li2S-P2S5등과 같은 P2S5계열 glass (Li x P y S z , 0 <x<3, 0<y<3, 0<z<7), 또는 이들의 혼합물 등이 있으나, 이에 한정되는 것은 아니다.

[0156] Additionally, examples of inorganic particles having a dielectric constant of 1 or greater include, but are not limited to, SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiC, or mixtures thereof.

[0157] The above thermally conductive inorganic particles are materials having insulating properties by providing low thermal resistance but no electrical conductivity, and may be, for example, at least one selected from the group consisting of aluminum nitride (AlN), boron nitride (BN), alumina (Al2O3), silicon carbide (SiC), and beryllium oxide (BeO), but are not limited thereto.

[0158] When the aforementioned high-k inorganic particles, piezoelectric inorganic particles, thermally conductive inorganic particles, and inorganic particles having lithium ion transfer capability are mixed, their synergistic effect can be doubled.

[0159] The size of the above-mentioned inorganic particles is not limited, but it is preferably in the range of 0.001 to 10 ㎛ to ensure an appropriate porosity between the inorganic particles. If it is less than 0.001 ㎛, dispersibility is reduced, making it difficult to control physical properties. If it exceeds 10 ㎛, the thickness increases, resulting in a deterioration in mechanical properties. In addition, due to the excessively large pore size, the coating layer cannot sufficiently function, increasing the probability of an internal short circuit occurring during battery charging and discharging.

[0160] The content of the above-mentioned inorganic particles is not particularly limited, but is preferably in the range of 1 to 99 wt%, and particularly 10 to 95 wt%, per 100 wt% of the mixture of inorganic particles and binder. When it is less than 1 wt%, the content of the binder becomes too high, which may reduce the pore size and porosity due to a decrease in the empty space formed between the inorganic particles, thereby reducing the mobility of lithium ions. Conversely, when it exceeds 99 wt%, the content of the binder becomes too low, which may result in a decrease in the adhesive strength between the inorganic particles, thereby reducing the mechanical properties of the coating layer.

[0161] Meanwhile, the binder is not limited as long as it does not cause a side reaction with the electrolyte, but in particular, one having a glass transition temperature (Tg) as low as possible can be used, preferably in the range of -200 to 200°C. This is because the mechanical properties of the final insulating film can be improved.

[0162] In addition, the above-mentioned binder does not necessarily need to have ion conducting ability, but it is more preferable to use a polymer having ion conducting ability.

[0163] Therefore, it is preferable that the binder have a permittivity constant as high as possible, and since the degree of salt dissociation in the electrolyte actually depends on the permittivity constant of the electrolyte solvent, the higher the permittivity constant of the polymer, the better the degree of salt dissociation in the electrolyte. The permittivity constant of the polymer is preferably 1 or more, specifically, in the range of 1.0 to 100 (measurement frequency = 1 kHz), and is particularly preferably 10 or more.

[0164] In addition to the aforementioned functions, the binder may have the characteristic of being gelled when impregnated with a liquid electrolyte, thereby exhibiting a high degree of swelling. In fact, if the binder is a polymer having an excellent electrolyte impregnation rate, the electrolyte injected after battery assembly permeates the polymer, and the polymer retaining the absorbed electrolyte has electrolyte ion conductivity. Therefore, if possible, the solubility index should be set to be 15 to 45 MPa. 1 / 2 Polymers are preferred, with a viscosity of 15 to 25 MPa. 1 / 2 and 30 to 45 MPa 1 / 2 The range is more desirable. The solubility index is 15 MPa. 1 / 2 Less than and 45 MPa 1 / 2 If it exceeds , it becomes difficult to be impregnated (swelled) by a conventional battery liquid electrolyte.

[0165] Examples of such binders include polyvinylidene fluorideco-hexafluoropropylene, polyvinylidene fluoride-cotrichloroethylene, polymethylmethacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, polyimide, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, It may be at least one selected from the group consisting of cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, carboxyl methyl cellulose, and polyvinylalcohol.

[0166] The total thickness of the separator may be 5 micrometers to 20 micrometers, specifically 5 micrometers to 15 micrometers, and more specifically 6 micrometers to 13 micrometers. When the thickness of the separator satisfies the above range, the resistance value of the lithium secondary battery can be minimized while effectively preventing a short circuit between the positive and negative electrodes. As a result, the reduction in energy density of the lithium secondary battery can be prevented and the life characteristics can be improved.

[0167]

[0168] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0169]

[0170] Examples 1 to 3: Preparation of electrolyte

[0171] The compound represented by the above chemical formula 2 was dissolved in DMSO with LiOH at a molar ratio of 1:2. In addition, the compound represented by the above chemical formula 3 was also dissolved in DMSO. Thereafter, these were mixed so that the amine monomer and the aldehyde monomer had a molar ratio of 3:2, and the polymerization reaction was carried out at room temperature for 1 day.

[0172] In Example 1, the molar concentration of the amine monomer was 0.01 mmol / mL and the molar concentration of the aldehyde monomer was 0.0067 mmol / mL, in Example 2, the molar concentration of the aldehyde monomer was 0.03 mmol / mL and the molar concentration of the aldehyde monomer was 0.0200 mmol / mL, and in Example 3, the molar concentration of the aldehyde monomer was 0.05 mmol / mL and the molar concentration of the aldehyde monomer was 0.033 mmol / mL.

[0173] The material in which the polymerization reaction was completed was applied to a glass substrate and dried at 60 degrees Celsius for 7 days to manufacture a COF film solid electrolyte having the unit structure of the chemical formula 1.

[0174]

[0175] Comparative Example 1: Preparation of electrolyte

[0176] To prepare the COF material in powder form, an amine monomer and an aldehyde monomer were adjusted to a molar ratio of 3:2, added to an ampoule containing a 1.5 mL solution of 1,4-dioxane and mesitylene (1:1 by volume), reacted for 15 minutes, mixed, and then 0.3 mL of a 6 M acetic acid (aq) solution was added. Afterwards, the inside of the ampoule was vacuumed using the freeze-pump-thaw method, reacted at 120°C for 3 days, and then the remaining monomers were removed through a purification process to prepare the COF material in powder form.

[0177] The COF powder was manufactured into pellets by replacing protons with lithium ions through a 3M LiOAC(aq) solution, placing 20 mg of the COF powder with the replaced lithium ions into a pressure vessel with a diameter of 12 mm and applying 300 MPa.

[0178]

[0179] Experimental Example 1: Evaluation of COF film solid electrolyte thickness according to molar concentration

[0180] The thickness of the COF film solid electrolyte manufactured in Examples 1 to 3 was measured, and the results are shown in Figure 3 below.

[0181] In addition, the cross-sectional view and plan view of the COF film solid electrolyte manufactured in Example 1 were photographed using SEM and are shown in FIGS. 4 and 5.

[0182] Referring to FIG. 3, it can be confirmed that as the molar concentration of the amine monomer increases, the thickness of the COF film solid electrolyte also becomes thicker, with Example 1 being about 20 ㎛, Example 2 being about 40 ㎛, and Example 3 being about 60 ㎛. Referring to FIGS. 4 and 5, it can be confirmed that when the molar concentration of the amine monomer is 0.01 mmol / mL, the thickness becomes 17.4 ㎛ and about 20 ㎛, and it can be confirmed that the surface is very even.

[0183]

[0184] Experimental Example 2: Evaluation of the Properties of COF Film Solid Electrolyte 1

[0185] The spectrum results through FT-IR evaluation of the COF film solid electrolyte manufactured in Example 1 are shown in Fig. 6 below, and the XRD pattern is shown in Fig. 7.

[0186] Specifically, FT-IR evaluation is performed by passing IR light in the range of 500 to 4000 cm-1 through the manufactured COF film solid electrolyte using a ZnS crystal in Attenuated Total Reflectance (ATR) mode at 25°C to collect spectral data, and XRD diffraction is performed by irradiating and detecting X-rays on the manufactured COF film solid electrolyte at 25°C.

[0187] Referring to FIGS. 6 and 7, it can be observed that the main functional groups (C=C, CN, O=S=O) exist in the synthesized COF film solid electrolyte through the FT-IR spectrum, and it can be seen from the XRD pattern that the COF film solid electrolyte has high crystallinity and matches well with the theoretically calculated value, and it can be confirmed that no monomers used in the synthesis remain.

[0188]

[0189] Experimental Example 3: Evaluation of the Properties of COF Film Solid Electrolyte 2

[0190] The nitrogen adsorption / desorption curve and pore distribution of the COF film solid electrolyte manufactured in Example 1 were measured, and the results are shown in Fig. 8 below. A surface TEM photograph was taken, and the results are shown in Fig. 9 below.

[0191] Specifically, about 0.03 mg of the above-manufactured COF film solid electrolyte sample was prepared and dried at 120°C for 12 hours to remove internal moisture, and then the specific surface area was measured under conditions of an absolute temperature of 77 K in a liquid nitrogen environment. In addition, using the nitrogen adsorption / desorption curve obtained at this time, a pore distribution was obtained through the Non Local Density Functional Theory (NLDFT) method, and the pore diameter was measured using this pore distribution.

[0192] In addition, using TEM equipment with a voltage of 300 kV, images were obtained that could observe materials smaller than 10 nm with a resolution of more than 200 k, and the spacing between lattices shown in the images was directly measured.

[0193] Referring to FIGS. 8 and 9, it can be confirmed that the COF film solid electrolyte manufactured according to the present invention has a uniform pore size of approximately 2.11 nm along with a high specific surface area, and a high-resolution TEM image shows that the interlayer spacing is 0.34 nm. From this, it can be confirmed that it has a structure similar to the theoretically calculated structure.

[0194]

[0195] Experimental Example 4: Evaluation of COF Solid Electrolyte Properties 3

[0196] A symmetrical cell was manufactured by combining the COF film solid electrolyte manufactured in Examples 1 to 3 and Comparative Example 1, Working electrode: Ti 25 ㎛, Counter electrode: Ti 25 ㎛, and the ion conductivity at 25°C was evaluated, and the results are shown in Figure 10 below.

[0197] The above ionic conductivity was measured using an impedance spectrometer by preparing a COF film solid electrolyte sample manufactured above. At this time, the temperature range was maintained at 60 degrees Celsius for more than 2 hours, and then maintained at 25 degrees Celsius for more than 1 hour, and then the measurement was performed by controlling the amplitude to 10 mV and the frequency to 1 MHz to 0.1 Hz to obtain a Nyquist plot, which is a polar coordinate diagram.

[0198] Referring to Figure 10, it can be confirmed that as the thickness of the COF film solid electrolyte decreases, the ionic conductivity increases.

[0199]

[0200] Experimental Example 5: Evaluation of COF Solid Electrolyte Properties 4

[0201] A symmetrical cell was manufactured by combining the solid electrolytes manufactured in Examples 1 to 3 and Comparative Example 1, working electrode: Li 150 μm, and counter electrode: Li 150 μm, and the interface resistance with the working electrode at 25 degrees Celsius was evaluated, and the results are shown in Figure 11 below.

[0202] The above interfacial resistance evaluation was performed using electrochemical impedance spectroscopy after storing for 2 hours at 60 degrees Celsius and then maintaining for more than 1 hour at 25 degrees Celsius, and then measuring the interfacial resistance using a Nyquist diagram at an amplitude of 10 mV and a frequency of 1 MHz to 0.1 Hz.

[0203] Referring to Figure 11, it can be confirmed that as the thickness of the COF film solid electrolyte becomes thinner, the interfacial resistance with the Li electrode decreases significantly, and when a pellet is used as the solid electrolyte, the interfacial resistance increases significantly.

[0204]

[0205] Experimental Example 6: Evaluation of COF Solid Electrolyte Properties 5

[0206] A symmetrical cell was manufactured by combining the solid electrolyte manufactured in Example 1, Working electrode: Ti 25 μm, Counter electrode: Li 150 μm, and oxidation stability at 25 degrees Celsius was evaluated, and the results are shown in Figure 12 below.

[0207] The above oxidation stability evaluation was performed by measuring the current while increasing the voltage at a rate of 0.1 mV / s from the open circuit potential to 5 V.

[0208] Referring to FIG. 12, it can be seen that the COF film solid electrolyte according to the present invention has stability up to 4.5 V.

[0209]

[0210] Experimental Example 7: Lithium Symmetric Cell Overvoltage Evaluation

[0211] A symmetrical cell was manufactured by combining the solid electrolytes manufactured in Example 1 and Comparative Example 1, working electrode: Li 150 μm, counter electrode: Li 150 μm, and current density: 0.01-0.3 mA / cm 2 , Capacity: 0.01-0.3 mAh / cm 2 An electrochemical reaction was performed, and the resulting overvoltage graphs are shown in Figures 13 and 14.

[0212] Referring to FIGS. 13 and 14, it was observed that when a thin COF film solid electrolyte was used, it exhibited a lower overvoltage than a thick COF pellet electrolyte, and it was confirmed that the contact at the interface between the Li electrode and the solid electrolyte was improved.

[0213]

[0214] Experimental Example 8: Evaluation of Lithium Symmetric Cell Lifetime Characteristics

[0215] The lithium symmetric cell used in the above experimental example 7 was combined in the same manner. The solid electrolyte used was the solid electrolyte of Example 1, Example 2, and Comparative Example 1, and the current density was 0.1 mA / cm. 2 , Capacity: 0.1 mAh / cm 2 The life characteristics were evaluated, and the evaluation results are shown in Fig. 15.

[0216] Referring to Figure 15, it can be confirmed that when the thin COF film solid electrolyte of Example 1 was used, the lithium symmetric cell life was significantly improved with a lower overvoltage compared to when the pellet solid electrolyte was used.

[0217]

[0218] Experimental Example 9: Lithium Full Cell Evaluation 1

[0219] A full cell was manufactured by combining the solid electrolyte manufactured in Examples 1 to 3, working electrode: LiFePO4, counter electrode: Li 40 μm, and after performing charge / discharge twice at 0.05 C, charge / discharge was performed according to current density, and the capacity was measured, and the results are shown in Figure 16 below.

[0220] Referring to Figure 16, it can be observed that the thinner the COF film solid electrolyte, the higher the capacity is even at a high current density.

[0221]

[0222] Experimental Example 10: Lithium Full Cell Evaluation 2

[0223] A full cell was manufactured by combining the solid electrolyte manufactured in Example 1, working electrode: LiFePO4, and counter electrode: Li 40 μm, and after performing charge / discharge twice at 0.05 C at 25 degrees Celsius, charge / discharge was performed at 0.2 C and 0.5 C, and the capacity change rate was measured, and the results are shown in Figures 17 and 18 below.

[0224] Referring to Figures 17 and 18, it can be confirmed that the life evaluation also shows improved high life performance of more than 200 cycles.

[0225] The COF film solid electrolyte according to the present invention has the effect of improving ion conductivity and significantly reducing interfacial resistance with a Li electrode by having a COF, i.e., a single ion-conducting organic skeleton structure, in which anions are fixed inside.

[0226] In addition, since it can be produced in the form of a thin film based on high processability and can be deposited on an electrode, contact with the electrode interface can be improved, and thus there is an effect of increasing the cell performance of a lithium secondary battery including the COF film solid.

Claims

1. A COF (covalent organic framework) film solid electrolyte having a unit structure represented by the following chemical formula 1 and linked by a beta-ketoenamine functional group, and including a lithium sulfonate functional group. [Chemical Formula 1] 2. In the first paragraph, the COF (covalent organic framework) film solid electrolyte is a COF film solid electrolyte which is a polymer of a lithium salt, a 3,3-disulfobenzidine monomer, and a 1,3,5-triformylphloroglucinol monomer:

3. In the first paragraph, the COF film solid electrolyte is a COF film solid electrolyte, each of which has a pore diameter in the range of 1.5 nm to 2.5 nm.

4. In the third paragraph, the COF film solid electrolyte is a COF film solid electrolyte having uniform pores in which each pore diameter has a difference of 0.1 nm or less.

5. A COF film solid electrolyte in the first paragraph, wherein the interlayer spacing of the COF film solid electrolyte is 0.3 nm to 0.4 nm.

6. In the first paragraph, the COF film solid electrolyte has a thickness of 1 to 60 μm.

7. In the first paragraph, the specific surface area of ​​the COF film solid electrolyte is 250 m 2 / g to 300m 2 / g COF film solid electrolyte.

8. In the first paragraph, the COF film solid electrolyte has a surface roughness (Rz) of 1 nm to 30 nm.

9. In the first paragraph, a COF film solid electrolyte having an interfacial resistance with the Li electrode of 100Ω to 1000Ω.

10. A method for manufacturing a COF film solid electrolyte according to Article 1, A method for manufacturing a COF film solid electrolyte, comprising reacting a lithium salt, an amine monomer, and an aldehyde monomer in a molar ratio of 3:2 in a DMSO (dimethyl sulfoxide) solvent to synthesize a COF film.

11. In the 10th paragraph, the amine group monomer is a COF film solid electrolyte manufacturing method represented by the following chemical formula 2: [Chemical formula 2] 12. In the 10th paragraph, the aldehyde monomer is a COF film solid electrolyte manufacturing method represented by the following chemical formula 3: [Chemical Formula 3] 13. In the 10th paragraph, the method for manufacturing the COF film solid electrolyte is as follows: (a) Mixing the lithium salt and the amine monomer under a DMSO solvent, and mixing the aldehyde monomer under a DMSO solvent to prepare pre-solutions 1 and 2, respectively. (b) Mix the above solvents 1 and 2 and polymerize them, (c) crystallizing the polymerized solution, (d) A method for manufacturing a COF film solid electrolyte, comprising a process of coating and drying the crystallized solution in a film form.

14. In paragraph 13, A method for manufacturing a COF film solid electrolyte, wherein the molar concentration of the amine monomer in the above-described pre-solution 1 is 0.01 mmol / mL to 0.05 mmol / mL, and the molar concentration of the aldehyde monomer in the above-described pre-solution 2 is 0.0067 mmol / mL to 0.033 mmol / mL.

15. In paragraph 13, A method for producing a COF film solid electrolyte, wherein the crystallization is performed by leaving the polymerized solution at 20 to 30 degrees Celsius for 20 to 30 hours.

16. In paragraph 13, A method for manufacturing a COF film solid electrolyte, wherein the above drying is performed at 50 to 80 degrees Celsius for 5 to 10 days.

17. A lithium secondary battery comprising a COF film solid electrolyte according to Article 1, A lithium secondary battery comprising a positive electrode, a negative electrode, and a COF film solid electrolyte interposed between the positive electrode and the negative electrode.

18. A lithium secondary battery in claim 17, wherein the positive electrode includes lithium iron phosphate as a positive electrode active material.

19. A lithium secondary battery in accordance with claim 17, wherein the negative electrode comprises lithium metal as a negative electrode active material.

20. A lithium secondary battery according to claim 17, wherein the thickness of the COF film solid electrolyte is 1 ㎛ to 60 ㎛.

21. In paragraph 17, The above lithium secondary battery further includes a separator between the positive electrode and the negative electrode.

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