Polyamide polymers for binders, slurries containing the same, electrodes, separation membranes, and secondary batteries.

Abstract

This invention provides a binder that simultaneously ensures improved bonding strength and flexibility, offers excellent stability, and can improve the lifespan characteristics of lithium secondary batteries. [Solution] The present invention provides a polyamide polymer for binders containing an ether group, a linear or branched hydrocarbon group having 1 to 10 carbon atoms, or a first monomer unit containing a combination thereof, a slurry containing the same, an electrode, a separation membrane, a slurry composition for an insulating coating layer on a plain portion of a secondary battery, and a secondary battery.

Description

[Technical Field]

[0001] The present invention relates to a polyamide polymer for binders, a slurry containing the same, electrodes, a separation membrane, a slurry composition for an insulating coating layer on a plain portion of a secondary battery, and a secondary battery. [Background technology]

[0002] Lithium-ion batteries have a high energy density and are widely used in the electrical, electronics, communications, and computer industries. Following their use in small lithium-ion batteries for portable electronic devices, their applications are expanding to include high-capacity batteries for hybrid and electric vehicles.

[0003] In order to provide a lithium secondary battery with high energy density and excellent lifespan characteristics, it is preferable to increase the content of electrode active material and conductive material in the electrode and decrease the content of binder.

[0004] However, a decrease in binder content reduces the dispersibility, binding strength, and flexibility of the electrode active material layer. As a result, the electrode active material may detach from the current collector during charging and discharging, leading to a decrease in cycle characteristics.

[0005] Therefore, a binder is needed that can ensure the dispersibility of electrode active materials and / or conductive materials within the electrode, as well as the bonding strength and flexibility of the electrode plates, even with a small content.

[0006] For example, fluorine-based binders such as polyvinylidene fluoride (PVDF) that do not contain polar groups exhibit less swelling in organic electrolytes, making it easier to maintain the electrode structure during battery operation and improving the dispersibility of the active material.

[0007] However, PVDF suffers from insufficient dispersibility of conductive materials, poor bonding strength of electrode plates, and poor electrode plate flexibility. In particular, PVDF may experience stability problems due to the generation of HF gas when exposed to basic conditions for extended periods.

[0008] Furthermore, while non-fluorinated binders such as hydrogenated acrylonitrile-butadiene binders offer improved dispersibility of conductive materials and flexibility of electrode plates compared to fluorinated binders, their binding strength remains insufficient.

[0009] Therefore, there is a need for a binder that can overcome the limitations of such conventional technologies, simultaneously ensure improved bonding strength and flexibility, offer excellent stability, and improve the lifespan characteristics of lithium secondary batteries. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Republic of Korea Patent Publication No. 10-2016-0040125 [Overview of the project] [Problems that the invention aims to solve]

[0011] Therefore, the present invention aims to provide a polyamide polymer for electrode binders that can improve the electrochemical properties and cycle characteristics of secondary batteries by applying a polyamide polymer for binders containing an ether group, a linear or branched hydrocarbon group having 1 to 10 carbon atoms, or a combination thereof, to an existing polyamide polymer binder, thereby preventing electrode detachment caused by lithium ion movement with improved binding characteristics.

[0012] Furthermore, the aim is to provide a binder that improves the charge / discharge efficiency and lifespan of secondary batteries.

[0013] The present invention aims to provide a slurry composition that improves the properties of secondary batteries using the aforementioned polyamide polymer for electrode binders.

[0014] Together with this, the present invention aims to provide electrodes, separation membranes with excellent performance to which the slurry composition is applied, and low-cost and high-performance secondary batteries including the same.

[0015] However, the problems to be solved by the present application are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

Means for Solving the Problems

[0016] One aspect of the present application includes a first monomer unit containing an ether group, a linear or branched hydrocarbon group having 1 to 10 carbon atoms, or a combination thereof. A polyamide polymer is provided.

[0017] Another aspect of the present application includes the polyamide polymer. A binder is provided.

[0018] Still another aspect of the present application includes the binder and an electrode active material, and provides a slurry.

[0019] ​​​​​​​​​​​​​​​​​​​​​​​​​​ We provide rechargeable batteries. [Effects of the Invention]

[0023] The binder of the present invention exhibits excellent binding properties, which can improve the electrochemical properties of secondary batteries, and can improve the capacity retention rate of secondary batteries by activating lithium ion movement and improving resistance within the battery.

[0024] Furthermore, the binder of the present invention can improve the charge / discharge efficiency and lifespan of secondary batteries.

[0025] In addition, the improved binding strength of the electrode binder of the present invention makes it possible to reduce the amount of binder used while increasing the amount of active material and conductive material, thereby providing a lithium secondary battery with high energy density at a low cost. [Modes for carrying out the invention]

[0026] The operation and effects of the invention will be described in more detail below through specific embodiments of the invention. However, these embodiments are presented merely as examples of the invention and do not define the scope of the invention's rights.

[0027] Prior to this, terms and words used in this specification and in the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner consistent with the technical idea of ​​the present invention, in accordance with the principle that inventors may appropriately define the concepts of terms in order to best describe their invention.

[0028] Therefore, it should be understood that the configurations of the embodiments described herein represent only one of the most preferred embodiments of the present invention and do not represent the entire technical concept of the present invention, and that a variety of equivalents and modifications may exist that can substitute for them at the time of filing.

[0029] In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “includes,” “equip,” or “possess” are intended to specify the existence of implemented features, figures, stages, components, or combinations thereof, and should be understood not to preemptively exclude the possibility of the existence or addition of one or more other features, figures, stages, components, or combinations thereof.

[0030] In this specification, the terms "from" and "~" in "a to b" and "a~b" which indicate a numerical range are defined as ≥ a and ≤ b.

[0031] A polyamide polymer according to one aspect of the present application may contain a first monomer unit comprising an ether group, a linear or branched hydrocarbon group having 1 to 10 carbon atoms, or a combination thereof.

[0032] In one embodiment, the first monomer unit may include a structure represented by the following chemical formula 1, comprising two aromatic rings linked to each other by a linear or branched hydrocarbon having 1 to 10 carbon atoms. [ka] R1 and R2 are independently hydrogen; or linear or branched hydrocarbons having 1 to 4 carbon atoms; m is between 1 and 4.

[0033] For example, R1 and R2 may each independently be hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, sec-butyl, or a combination thereof.

[0034] In one embodiment, the first monomer unit may be formed by polymerizing the first monomer represented by the following chemical formula 2. [ka] In the aforementioned chemical formula 2, a+b+c is between 1 and 10. X1, X2, and X3 are each independently an oxygen atom; or a linear or branched hydrocarbon having 1 to 10 carbon atoms.

[0035] For example, X1, X2, and X3 may each independently be an ether group (-O-), a linear or branched hydrocarbon having 1 to 10 carbon atoms that links the two aromatic rings of chemical formula 1, or a combination thereof.

[0036] In one embodiment, the first monomer is 4,4'-Oxydianiline (ODA), 3,4'-Methylenedianiline (MDA), 1,3-Bis(3-aminophenoxy)benzene (APB), 1,4-Bis(4-aminophenoxy)benzene, 1,3-Bis(4-aminophenoxy)benzene, 1,3-Bis[2-(4-aminophenyl)-2-propyl]benzene (1,3-Bis [2-(4-aminophenyl)-2-propyl]benzene), 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, 4,4'-isopropylidenebis[(4-aminophenoxy)benzene], 4,4'-(1,4-phenylenediisopropylidene)bisaniline, or a combination thereof.

[0037] In one embodiment, the polyamide polymer may additionally include a second monomer unit comprising at least one aromatic ring.

[0038] The at least one aromatic ring can be used to form part of the backbone of the polyamide polymer. That is, the polyamide polymer may contain an aromatic ring in its backbone.

[0039] The monomer unit comprising at least one aromatic ring must be able to polymerize with a diamine monomer to produce a polyamide polymer, and may contain substituents for this purpose.

[0040] In one embodiment, the polyamide polymer may additionally contain a third monomer unit containing a sulfone, a fourth monomer unit containing a carboxylic acid, or a combination thereof.

[0041] The third monomer unit containing the sulfone may also contain an aromatic ring. The sulfone, or the sulfone and aromatic ring of the third monomer unit containing the sulfone, can be used to form part of the main chain of the polyamide polymer. That is, the polyamide polymer may contain a sulfone, or a sulfone and an aromatic ring in its main chain.

[0042] The aforementioned third monomer unit containing sulfone can contribute to improving the binding properties of the polyamide polymer. Furthermore, it can significantly contribute to improving the performance of batteries.

[0043] In addition, the third monomer unit containing the sulfone can also contribute to improving the initial efficiency of the battery.

[0044] The fourth monomer unit containing the carboxylic acid may contain one or more carboxylic acids, and the carboxylic acid may be a substituent of an aromatic ring.

[0045] When used in an appropriate amount, the fourth monomer unit containing the carboxylic acid can improve the performance of the battery while improving the binding strength of the polyamide polymer.

[0046] In one embodiment, the polyamide polymer may be formed by polymerizing bis[4-(4-aminophenoxy)phenyl]sulfone (BAPS), 4,4'-oxydianiline (ODA), isophthaloyl chloride (IPC), and terephthaloyl chloride (TPC).

[0047] In one embodiment, the polyamide polymer may be formed by polymerizing bis[4-(4-aminophenoxy)phenyl]sulfone (BAPS), 3,4'-methylenedianilne (3,4'-MDA), isophthaloyl chloride (IPC), and terephthaloyl chloride (TPC).

[0048] In one embodiment, the polyamide polymer may be formed by polymerizing bis[4-(4-aminophenoxy)phenyl]sulfone (BAPS), 1,3-bis(3-aminophenoxy)benzene (APB), isophthaloyl chloride (IPC), and terephthaloyl chloride (TPC).

[0049] In one embodiment, the second monomer that polymerizes the second monomer unit containing at least one aromatic ring may be a terephthaloyl chloride monomer, an isophthaloyl chloride monomer, a phthalic acid monomer, an isophthalic acid monomer, a terephthalic acid monomer, or a combination thereof.

[0050] In one embodiment, the molar ratio of terephthaloyl chloride to isophthaloyl chloride (mol% of terephthaloyl chloride:mol% of isophthaloyl chloride) may be 100:0 to 0:100, based on a total content of 100 mol% of terephthaloyl chloride and isophthaloyl chloride used in the polymerization of the polyamide polymer.

[0051] For example, the molar ratio of terephthaloyl chloride to isophthaloyl chloride (moles of terephthaloyl chloride to isophthaloyl chloride) may be 90:10-10:90, 80:20-20:80, 75:25-25:75, 70:30-30:70, 50:50-90:10, 50:50-80:20, 50:50-70:30, 60:40-75:25, 60:40-70:30, or 70:30.

[0052] In other words, terephthaloyl chloride and isophthaloyl chloride can be used together for the polymerization of the polyamide polymer of this application.

[0053] In one embodiment, the third monomer unit formed by polymerization of the sulfone-containing third monomer unit is bis[4-(4-aminophenoxy)phenyl]sulfone, bis(4-aminophenyl)sulfone, bis(3-aminophenyl)sulfone, 3,3'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 1,3-bis(3-aminophenylsulfone)benzene 1,3-bis(3-aminophenyl)sulfone), 1,3-bis(4-aminophenylsulfone)benzene (1,3-bis(4-aminophenyl)sulfone), 1,4-bis(4-aminophenylsulfone)benzene (1,4-bis(4-aminophenyl)sulfone), bis[3-(3-aminophenoxy)phenylsulfone (bis[3-(3-aminophenoxy)phenyl]sulfone), bis[3-(4-aminophenoxy)phenylsulfone (bis[3-(4-aminophenoxy)phenyl]sulfone), bis[4-(3-aminophenoxy)phenylsulfone (bis[4-(3-aminophenoxy)phenyl]sulfone), or a combination thereof.

[0054] In particular, when bis[4-(4-aminophenoxy)phenyl]sulfone is used, the bonding properties of polyamide polymers can be greatly improved. Furthermore, it can greatly contribute to improving the characteristics of batteries using positive electrodes to which bis[4-(4-aminophenoxy)phenyl]sulfone is applied (for example, the initial efficiency characteristics of the battery).

[0055] In one embodiment, the fourth monomer unit that polymerizes to form the fourth monomer unit containing the carboxylic acid may be 5,5'-methylenebis(2-aminobenzoic acid) (MBAA), 3,5-diaminobenzoic acid (DABA), or a combination thereof.

[0056] The carboxylic acid 5,5'-methylenebis(2-aminobenzoic acid) or 3,5-diaminobenzoic acid can contribute to improving the binding strength with the aluminum current collector.

[0057] In one embodiment, the polyamide polymer may have a total content of 100 mol% of the third monomer units and the first monomer units, with a molar ratio of the third monomer units to the first monomer units (mol% of the third monomer units:mol% of the first monomer units) of 90:10 to 1:99.

[0058] In other words, the molar ratio (mol% of the third monomer:mol% of the first monomer) of the third monomer unit formed by polymerization and the first monomer unit formed by polymerization of the first monomer unit may be 90:10 to 1:99.

[0059] For example, the molar ratio of the third monomer to the first monomer (mol% of the third monomer:mol% of the first monomer) may be 90:10 to 5:95, 90:10 to 10:90, 80:20 to 1:99, 80:20 to 5:95, 80:20 to 10:90, 70:30 to 10:90, or 70:30 to 20:80.

[0060] If the content of the diamine monomer containing the ether group, the linear or branched hydrocarbon group having 1 to 10 carbon atoms, or a first monomer unit including a combination thereof exceeds the content specified in this application, the diamine monomer containing the ether group, the linear or branched hydrocarbon group having 1 to 10 carbon atoms, or a first monomer unit including a combination thereof has a lower molecular weight than the diamine monomer containing the sulfone, a decrease in binding strength due to the limit of molecular weight increase may occur, and the performance of the battery may deteriorate.

[0061] On the other hand, if the content of diamine monomers including the ether group, linear or branched hydrocarbon group having 1 to 10 carbon atoms, or a first monomer unit containing a combination thereof falls below the content specified in this application, a decrease in binding strength may occur, and the performance of the battery may deteriorate.

[0062] In one embodiment, the polyamide polymer may contain repeating monomer units represented by the following chemical formula 3. [ka] In the above chemical formula 3, Y1 comprises at least one aromatic ring substituted with a halogen element, hydrogen, a hydroxyl group, a carboxyl group, a linear or branched hydrocarbon group having 1 to 4 carbon atoms, or a combination thereof; Y2 comprises two aromatic rings linked together by -SO2-; an aromatic ring substituted with at least one carboxyl group; an oxygen atom; or two aromatic rings linked together by a linear or branched hydrocarbon group having 1 to 10 carbon atoms; or a combination thereof, wherein the two aromatic rings linked together by -SO2- may be substituted with a halogen element, hydrogen, a hydroxyl group, a carboxyl group, a linear or branched hydrocarbon group having 1 to 4 carbon atoms substituted or unsubstituted with a halogen element, or a combination thereof, and c+d=1, a polyamide polymer. (However, Y2 must always comprise an oxygen atom or two aromatic rings linked together by a linear or branched hydrocarbon group having 1 to 10 carbon atoms.) In the above chemical formula 3, c and d represent mole fractions.

[0063] The halogen element in the chemical formula 3 does not necessarily have to contain fluorine.

[0064] The monomer unit corresponding to Y1 in the aforementioned chemical formula 3 corresponds to a monomer unit containing at least one aromatic ring.

[0065] For example, the monomer that polymerizes to form the monomer unit corresponding to Y1 in the chemical formula 3 may be terephthaloyl chloride monomer, isophthaloyl chloride monomer, phthalic acid monomer, isophthalic acid monomer, terephthalic acid monomer, or a combination thereof.

[0066] Furthermore, the monomer that forms the monomer unit corresponding to Y2 in the chemical formula 3 by polymerization may be a diamine monomer containing a sulfone and at least one aromatic ring, a diamine monomer containing a carboxylic acid, an oxygen atom, a linear or branched hydrocarbon having 1 to 10 carbon atoms, or a combination thereof, or a combination thereof.

[0067] For example, a diamine monomer containing a sulfone that polymerizes to form a monomer unit corresponding to Y2 in the above chemical formula 3, and at the same time containing at least one aromatic ring, is bis[4-(4-aminophenoxy)phenyl]sulfone, bis(4-aminophenyl)sulfone, bis(3-aminophenyl)sulfone, 3,3'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 1,3-bis(3-aminophenyl) It may also be 1,3-bis(3-aminophenyl)sulfone, 1,3-bis(4-aminophenylsulfone)benzene, 1,4-bis(4-aminophenylsulfone)benzene, bis[3-(3-aminophenoxy)phenyl]sulfone, bis[3-(3-aminophenoxy)phenyl]sulfone, bis[3-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, or a combination thereof.

[0068] Furthermore, the diamine monomer containing a carboxylic acid that forms a monomer unit corresponding to Y2 in the above chemical formula 3 by polymerization may be 5,5'-methylenebis(2-aminobenzoic acid) (MBAA), 3,5-diaminobenzoic acid (DABA), or a combination thereof.

[0069] Furthermore, for example, diamine monomers containing an oxygen atom, a linear or branched hydrocarbon having 1 to 10 carbon atoms, or a combination thereof, which polymerize to form a monomer unit corresponding to Y2 in the above chemical formula 3, include 4,4'-oxydianiline (ODA), 3,4'-methylenedianiline (MDA), 1,3-bis(3-aminophenoxy)benzene (APB), 1,4-bis(4-aminophenoxy)benzene (1,4-Bis(4-aminophenoxy)benzene), 1,3-bis(4-aminophenoxy)benzene (1,3-Bis(4-aminophenoxy)benzene), and 1,3-bis [2-(4-aminophenyl)-2-propyl]benzene (1,3-Bis[2-(4-aminophenyl)-2-propyl]benzene), 4,4'-Diaminodiphenylmethane, 4,4'-Diaminodiphenylethane, 4,4'-Isopropylidenebis[(4-aminophenoxy)benzene], 4,4'-(1,4-Phenylenediisopropylidene)bisaniline, or a combination thereof.

[0070] In one embodiment, the weight-average molecular weight of the polyamide polymer may be 50,000 or more and 1,000,000 or less.

[0071] Within the range of weight-average molecular weight of the polyamide polymer of this application, the higher the weight-average molecular weight, the higher the binding strength of the polyamide polymer may become.

[0072] If the weight-average molecular weight of the polyamide polymer is less than 50,000, the stability of the electrolyte of the electrode binder containing the polyamide polymer may decrease. Furthermore, the stability of the electrode slurry containing the binder containing the polyamide polymer may also decrease.

[0073] On the other hand, if the weight-average molecular weight of the polyamide polymer exceeds 1,000,000, the viscosity may become high during slurry production, making slurry coating difficult.

[0074] Binders according to other embodiments of the present application may include the polyamide polymer.

[0075] A slurry according to yet another aspect of the present application may include the binder and the electrode active material.

[0076] In one embodiment, the slurry may contain, as a solvent, organic solvents such as carboxymethylcellulose, NMP (N-methylpyrrolidone), DMF (dimethylformamide), acetone, dimethylacetamide, or water, and preferably, carboxymethylcellulose can be used. The slurry may also contain one or more solvents.

[0077] The carboxymethylcellulose may have 0.7 to 1.2 substituents on the hydroxy(-OH) group by the carboxymethyl group (-CH2CO2H), a molecular weight (Mn) of 500,000 to 900,000, and a pH of 6.5 to 8.0.

[0078] Furthermore, the slurry may contain an electrode active material in which carboxymethyl cellulose (CMC) and lithium ions can intercalate and deintercalate.

[0079] For example, the slurry may be a positive electrode slurry, a negative electrode slurry, or a combination thereof.

[0080] The electrode active material used in the present invention can be any electrode active material available in the relevant technical field.

[0081] In one embodiment, the electrode active material is a substance capable of undergoing an electrochemical reaction, and is used in the production of negative and positive electrode slurries. There are negative electrode active materials and positive electrode active materials according to the type of electrode.

[0082] The negative electrode active material may be selected from one or more of the group consisting of carbon and graphite materials capable of lithium ion intercalation and deintercalation, Si-based materials, metals and compounds alloyable with lithium, composites of metals and their compounds with carbon and graphite materials, lithium-containing nitrides, and the like.

[0083] Examples of carbon and graphite materials include natural graphite, artificial graphite, expanded graphite, carbon fiber, non-graphitizable carbon, carbon black, carbon nanotube, fullerene, activated carbon, hard carbon, and soft carbon. Examples of Si-based materials include Si, SiO x (0 < x < 2), Si-Y alloy (where Y is an alkali metal, alkaline earth metal, group 13 element, group 14 element, transition metal, rare earth element, or a combination thereof), Si-C composite, or Si-based compounds such as a combination thereof. Examples of metals and elements alloyable with lithium include Al, Si, Sn, Ag, Bi, Mg, Zn, In, Ge, Pb, Pd, Pt, Ti, and the like. The negative electrode slurry can contain the negative electrode active material in a content of 20 to 80 parts by weight based on 100 parts by weight of the negative electrode slurry.

[0084] Specific examples of the positive electrode active material include lithium metal; lithium cobalt-based oxides such as LiCoO2; Li 1+x Mn 2-xO4 (where x is from 0 to 0.33), lithium manganese oxides such as LiMnO3, LiMn2O3, LiMnO2; lithium copper oxides such as Li2CuO2; vanadium oxides such as LiV3O8, V2O5, Cu2V2O7; LiNi 1-x M x O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x = 0.01 to 0.3), lithium nickel oxides represented by; LiMn 2-x M x O2 (where M = Co, Ni, Fe, Cr, Zn or Ta, and x = 0.01 to 0.1) or lithium manganese composite oxides represented by Li2Mn3MO8 (where M = Fe, Co, Ni, Cu or Zn); Li(Ni a Co b Mn c )O2 (where 0 < a < 1, 0 < b < 1, 0 < c < 1, and a + b + c = 1), lithium-nickel-manganese-cobalt oxides; sulfur or disulfide compounds; phosphates such as LiFePO4, LiMnPO4, LiCoPO4, LiNiPO4; Fe2(MoO4)3, etc., but not limited to only these.

[0085] As the secondary battery binder, in addition to the binder containing the polyamide polymer containing the monomer unit containing the aromatic ring of the present application, poly(meth)acrylic acid, poly(meth)acrylamide, carboxymethyl cellulose, polyvinylidene fluoride, copolymer of polyhexafluoropropylene - polyvinylidene fluoride (P(VdF / HFP)), poly(vinyl acetate), polyvinyl alcohol, polyethylene oxide, polyvinyl pyrrolidone, alkylated polyethylene oxide, polyvinyl ether, poly(methyl methacrylate), poly(ethyl acrylate), polytetrafluoroethylene, polyvinyl chloride, polyacrylonitrile, polyvinyl pyridine, styrene - butadiene rubber, acrylonitrile - butadiene rubber, and any one of these copolymers, or two or more of them can be selected and used together.

[0086] The content of the binder in the slurry composition is preferably 0.3 wt% to 10 wt% on a solid content basis, and more preferably 0.7 wt% to 8 wt%. If the content is less than 0.3 wt%, it is difficult to expect sufficient binding force in the current collector and electrode composition, and if the content exceeds 10 wt%, the proportion of binder in the electrode slurry composition increases, which may reduce the battery capacity.

[0087] An electrode according to yet another aspect of the present application may include a current collector and an electrode active material layer comprising the binder of the present application, a plain insulating coating layer, or a combination thereof, formed on the current collector.

[0088] For example, the electrode may be a positive electrode, a negative electrode, or a combination thereof.

[0089] In one embodiment of the present invention, the current collector is the part where electron movement occurs in the electrochemical reaction of the active material, and depending on the type of electrode, there are negative electrode current collectors and positive electrode current collectors. The current collector can also have fine irregularities formed on its surface to strengthen the bonding force of the electrode active material, and can be used in a variety of forms such as films, sheets, foils, nets, porous materials, foams, and nonwoven fabrics.

[0090] The negative electrode current collector may generally be formed to a thickness of 5 μm to 30 μm. Such a negative electrode current collector is not particularly limited as long as it is conductive without inducing a chemical change in the battery, and for example, copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, or a combination thereof can be used.

[0091] The positive electrode current collector may generally be formed to a thickness of 3 μm to 500 μm. The positive electrode current collector is not particularly limited as long as it has high conductivity without inducing 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., and aluminum-cadmium alloy can be used.

[0092] The electrode can be manufactured by (a) manufacturing an electrode active material layer forming composition comprising an electrode active material and the binder of the present invention, and (b) applying the electrode active material layer forming composition onto a current collector and then drying it.

[0093] The electrode active material layer forming composition can be mixed using a conventional mixer, such as a high-speed shear mixer or homomixer, in a conventional manner.

[0094] Step (b) is a step of manufacturing an electrode for a lithium secondary battery by applying the electrode active material layer forming composition manufactured in step (a) onto a current collector and then drying it.

[0095] At this time, there are no limitations on the method of applying the slurry-like electrode active material layer forming composition. For example, it can be manufactured by methods such as doctor blade coating, dip coating, gravure coating, slit die coating, spin coating, comma coating, bar coating, reverse roll coating, screen coating, and cap coating.

[0096] After coating and drying, electrodes for secondary batteries (especially lithium secondary batteries) can be manufactured with an electrode active material layer formed at the end.

[0097] The current collector can be any material that is conductive and does not chemically react with the electrode forming slurry. Typical examples include aluminum foil and copper foil. A current collector with a thickness of 3 to 50 micrometers can be selected and used.

[0098] In this case, the electrode active material layer may additionally contain, in addition to the electrode active material, a dispersant, a conductive material, a filler, and other additives.

[0099] The electrode active material may be present in an amount of 90-99% by weight on a solid content basis. If the active material content is too low, the battery may not be able to achieve high capacity, and if the active material content is too high, the content of binders, conductive materials, etc. will be relatively low, which may reduce the adhesive strength and conductivity of the electrodes.

[0100] The conductive material is not particularly limited and can be appropriately selected depending on the type of battery and energy storage device. For example, in the case of lithium-ion secondary batteries, graphite, activated carbon, and other carbon materials can be used, while in the case of nickel-metal hydride secondary batteries, cobalt oxide can be used, and nickel powder, cobalt oxide, titanium oxide, and carbon can be used for the negative electrode.

[0101] Examples of the aforementioned carbon include acetylene black, furnace black, graphite, carbon fibers, fullerenes, and carbon nanotubes.

[0102] The amount of conductive material used is usually 1 to 20 parts by weight, preferably 2 to 10 parts by weight, based on 100 parts by weight of the electrode active material.

[0103] Reducing the content of conductive material and increasing the content of electrode active material improves the energy density of the secondary battery; therefore, it is important to achieve high efficiency even when using the same amount of conductive material.

[0104] The smaller and more uniformly dispersed the conductive material used in the slurry for secondary batteries, the higher the conductivity, reducing resistance within the battery, resulting in improved power output and extended battery life. Conversely, if the material is large and unevenly dispersed, even with the same amount used, the binding properties and conductivity will be lower, negatively impacting the battery's lifespan and power output. Furthermore, lower viscosity of the dispersion allows for a higher solid content in the slurry, thereby increasing the electrode production rate.

[0105] Separation membranes according to other embodiments of the present invention may include a porous substrate coated with a slurry composition containing the binder of the present invention.

[0106] The separation membrane must be an insulator to separate the negative and positive electrodes and provide a passage through which only lithium ions can move. To achieve this, it must have good wettability with respect to the electrolyte, and porous polymer films such as PE / PP or porous nonwoven fabrics can be used. To prevent short circuits in the battery, coated separation membranes with enhanced heat resistance and mechanical strength, such as ceramic coatings, can be used, and may be coated in a single or multilayer configuration.

[0107] The separation membrane may be made of a porous substrate, but any porous substrate commonly used in electrochemical elements can be used, for example, a polyolefin-based porous membrane or a nonwoven fabric can be used, but is not particularly limited thereto.

[0108] The separation membrane may be a porous substrate made of any one selected from the group consisting of polyethylene, polypropylene, polybutylene, polypentene, polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyethersulfone, polyphenylene oxide, polyphenylene sulfide, and polyethylene naphthalate, or a mixture of two or more of these.

[0109] The slurry composition may contain inorganic particles. The inorganic particles can be any insulating particles and are preferably high dielectric constant insulating particles.

[0110] Specific examples of the inorganic particles include Al2O3, AlOOH, SiO2, TiO2, ZrO2, ZnO, NiO, CaO, SnO2, Y2O3, MgO, BaTiO3, CaTiO3, SrTiO3, SiC, Li3PO4, Pb(Zr,Ti)O3(PZT), (Pb,La)(Zr,Ti)O3(PLZT), and mixtures thereof.

[0111] The inorganic particles have no particular size restrictions, but for example, their average particle size may be 0.01 μm to 30 μm, and more preferably 0.1 μm to 10 μm. If the average particle size of the inorganic particles is below the preferred range, the dispersibility will be low, and if it exceeds the preferred range, the thickness of the coating layer after coating will be thicker, which may reduce the mechanical properties.

[0112] Furthermore, the inorganic particles are not limited in shape and may be, for example, spherical, plate-shaped, elliptical, or irregular in shape.

[0113] The slurry composition can be coated onto at least one surface of a porous substrate film, or the slurry composition can be manufactured into a film and laminated onto the porous substrate film to produce a separation membrane.

[0114] On the other hand, the separation membrane can be used as a separation membrane for secondary batteries, and may be used, for example, as a separation membrane for lithium secondary batteries.

[0115] As an example of separation membrane production, the process may include: (a) dissolving or dispersing the binder in a solvent to produce a polymer solution; (b) adding and mixing inorganic particles to the polymer solution from step a); and (c) coating and drying one or more regions selected from the group consisting of the surface of a polyolefin-based separation membrane substrate and a portion of the pores in the substrate with the mixture from step b).

[0116] First, 1) the binder is manufactured and prepared in the form of a polymer solution by dissolving or dispersing it in a suitable solvent.

[0117] Preferably, the solvent has a similar solubility index to the copolymer used as a binder and a low boiling point. This is to facilitate uniform mixing and subsequent solvent removal. Non-limiting examples of usable solvents include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or mixtures thereof. More preferably, the solvent can be used in a water dispersion.

[0118] 2) Inorganic particles are added to and dispersed in the manufactured polymer solution to produce inorganic particles and a polymer mixture.

[0119] It is preferable to carry out a dispersion step of polymer solution and inorganic particles. In this case, a dispersion time of 1 to 50 hours may be appropriate. Conventional methods can be used as the dispersion method, and the ball mill method is particularly preferred.

[0120] While there are no major restrictions on the composition of the mixture consisting of inorganic particles and polymers, this allows for adjustment of the thickness, pore size, and porosity of the organic-inorganic composite porous separation membrane of the present invention that is ultimately produced.

[0121] In other words, the higher the ratio of inorganic particles (I) to polymers (P) (ratio = I / P), the higher the porosity of the separation membrane, which results in an increase in the thickness of the separation membrane for the same solid content (weight of inorganic particles + weight of polymers). Also, the possibility of pore formation between inorganic particles increases, and the pore size increases. At this time, the larger the size of the inorganic particles (particle size), the greater the interstitial distance between inorganic particles, and thus the larger the pore size.

[0122] 3) The separation membrane of the present invention can be obtained by coating a mixture of manufactured inorganic particles and polymers onto a prepared polyolefin-based separation membrane substrate and then drying it.

[0123] At this time, the method for coating the mixture of inorganic particles and polymers onto the polyolefin-based separation membrane substrate can be any conventional coating method known in the industry, such as dip coating, die coating, roll coating, comma coating, or a mixture thereof. Furthermore, when coating the mixture of inorganic particles and polymers onto the polyolefin-based separation membrane substrate, the coating can be applied to both sides of the separation membrane substrate, or selectively to only one side.

[0124] A slurry composition for an insulating coating layer on a plain portion of a secondary battery according to yet another aspect of the present application may contain the binder of the present application.

[0125] Furthermore, the slurry composition for the insulating coating layer of the plain portion of the secondary battery may additionally contain inorganic particles, which may be AlOOH, Al2O3, γ-AlOOH, Al(OH)3, SiO2, silicon carbide (SiC), boron nitride (BN), or a combination thereof.

[0126] The slurry composition for the insulating coating layer of the plain portion of the secondary battery may contain, based on 100% by weight of the total weight of the binder and the inorganic particles, 5% by weight or more and 30% by weight or less of the binder, and 70% by weight or more and 95% by weight or less of the inorganic particles.

[0127] On the other hand, the solid content of the slurry composition for the insulating coating layer of the plain portion of the secondary battery may be 10% by weight or more and 45% by weight or less.

[0128] For example, the slurry composition for the insulating coating layer of the plain portion of the secondary battery can be applied to an electrode current collector and dried to produce the insulating coating layer of the plain portion of the secondary battery electrode.

[0129] A secondary battery according to yet another aspect of the present invention may include the binder of the present invention.

[0130] For example, the secondary battery may include a positive electrode, a negative electrode, a separator membrane, or a combination thereof, all containing the binder of the present invention.

[0131] The secondary battery may include a positive electrode, a negative electrode, a separation membrane interposed between the positive electrode and the negative electrode, and an electrolyte.

[0132] The aforementioned secondary battery can be manufactured by conventional methods known in the industry. One example of such a method involves assembling the electrodes and a separator membrane, and then injecting an electrolyte into the assembly.

[0133] On the other hand, the electrolyte of the secondary battery is a non-aqueous electrolyte containing a lithium salt, and is composed of a lithium salt and a solvent. As the solvent, non-aqueous organic solvents, organic solid electrolytes, and inorganic solid electrolytes are used.

[0134] The lithium salts mentioned above are substances that dissolve easily in the non-aqueous electrolyte, such as LiCl, LiBr, LiI, LiClO4, LiBF4, and LiB 10 Cl 10 LiPF6, LiAsF6, LiSbF6, LiAlCl4, LiSCN, LiC4BO8, LiCF3CO2, LiCH3SO3, LiCF3SO3, LiN(SO2CF3)2, LiN(SO2F)2, LiN(SO2C2F5)2, LiC4F9SO3, LiC(CF3SO2)3, (CF3SO2)·2NLi, lithium chloroborane, lithium lower aliphatic carboxylate, lithium 4-phenylborate imide, etc. can be used.

[0135] Non-aqueous organic solvents that can be used include, for example, aprotic organic solvents such as N-methyl-2-pyrrolidone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, gamma-butyrolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydroxyfuran (franc), 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, 4-methyl-1,3-dioxene, diethyl ether, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, triester phosphate, trimethoxymethane, dioxolane derivatives, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ethers, methyl propionate, and ethyl propionate.

[0136] Examples of the organic solid electrolytes that can be used include polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphate ester polymers, polyagitation lysine, polyester sulfides, polyvinyl alcohol, polyvinylidene fluoride, and polymers containing secondary dissociation groups.

[0137] Examples of the inorganic solid electrolytes that can be used include lithium nitrides, halides, and sulfates such as Li3N, LiI, Li5NI2, Li3N-LiI-LiOH, LiSiO4, LiSiO4-LiI-LiOH, Li2SiS3, Li4SiO4, Li4SiO4-LiI-LiOH, and Li3PO4-Li2S-SiS2.

[0138] Furthermore, non-aqueous electrolytes may contain other additives for the purpose of improving charge / discharge characteristics, flame retardancy, and other properties. Examples of such additives include pyridine, triethyl phosphite, triethanolamine, cyclic ethers, ethylenediamine, n-glyme, hexaphosphate triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salts, pyrrole, 2-methoxyethanol, aluminum trichloride, fluoroethylene carbonate (FEC), propensultone (PRS), vinylene carbonate (VC), and the like.

[0139] The lithium secondary battery according to the present invention can undergo processes other than the common winding process, such as lamination stacking and folding of the separation membrane and electrodes. The battery case may be cylindrical, rectangular, pouch-type, or coin-type.

[0140] In one embodiment, the initial discharge capacity of the secondary battery (cell) containing the binder of the present invention may be 190 mAh / g or more. For example, it may be 193mAh / g or higher, 195mAh / g or higher, or 196mAh / g or higher.

[0141] At this time, the initial discharge capacity can be set by charging to 4.2V at a 0.1C rate in CC / CV mode, then discharging to 2.8V at a 0.1C rate, then charging to 4.2V at a 0.2C rate, then discharging to 2.8V at a 0.2C rate, and then charging to 4.2V at a 0.5C rate, then discharging to 2.8V at a 0.5C rate. The chamber temperature can be set to 25°C.

[0142] Of the initial formations mentioned above, the discharge capacity during discharge at a rate of 0.1C up to 2.8 can be measured as the initial discharge capacity.

[0143] In one embodiment, the initial efficiency of the secondary battery (cell) containing the binder of the present invention may be 85% or more. For example, it could be 86% or higher, 87% or higher, or 87.15% or higher.

[0144] At this time, the initial efficiency can be calculated using the following formula 1.

number

[0145] In one embodiment, the DC-IR resistance of the secondary battery (cell) containing the binder of the present invention may be 23.5 mΩ or less. For example, it may be 23.4 mΩ or less, 23.3 mΩ or less, 23.2 mΩ or less, 23.1 mΩ or less, 23 mΩ or less, 21 mΩ or less, or 19.4 mΩ or less.

[0146] In one embodiment, the cycle stability of a secondary battery (cell) containing the binder of the present invention, calculated by measuring the battery's capacity after 100 cycles compared to its initial capacity (capacity at the first cycle), may be 95% or more. For example, it could be 95.5% or higher, 96% or higher, or 96.3% or higher.

[0147] To measure the capacity retention rate, the device is charged to 4.2V at a 1C rate in CC / CV mode, then discharged to 2.8V at a 1C rate, and the chamber temperature can be set to 25°C.

[0148] The aforementioned "C" represents the cell discharge rate, which is the value obtained by dividing the total capacity of the cell by the total discharge time.

[0149] The battery can be charged and discharged under these set conditions to perform cycle analysis, and one cycle can consist of one charge and one discharge.

[0150] When 100 cycles are completed, the battery capacity retention rate can be calculated using the following formula 2.

number

[0151] The present application will be described in more detail below using examples, but the present application is not limited thereto.

[0152] Manufacturing Example 1. Production of binder polymers [Example 1] In a 500 ml four-necked flask under a nitrogen atmosphere, N-methyl-2-pyrrolidone (NMP), the monomers 4,4'-oxydianiline (ODA) and (bis[4-(4-aminophenoxy)phenyl]sulfone (BAPS), which form monomer units containing an ether group, and the monomer 5,5'-methylenebis(2-aminobenzoic acid) (MBAA), which contains a carboxylic acid, were added and stirred.

[0153] The amount of MBAA was fixed at 5 mol% based on 100 mol% of the total molars of the polyamide copolymer used as a binder, and the molar ratio of bis[4-(4-aminophenoxy)phenyl]sulfone to 4,4'-oxydianiline was 7:3.

[0154] Subsequently, after lowering the internal temperature of the reactor to below 5°C, isophthaloyl chloride (IPC), a monomer unit containing an aromatic ring, was added and the reaction was carried out.

[0155] To this, terephthaloyl chloride (TPC), a monomer that forms monomeric units containing aromatic rings, was added and the mixture was stirred for a sufficient amount of time.

[0156] The molar ratio of isophthaloyl chloride to terephthaloyl chloride was 3:7.

[0157] An olefin-based neutralizing agent was added to the solution after its viscosity had increased to a certain level, and the mixture was stirred to remove the HCl generated during the synthesis process.

[0158] Finally, a polyamide copolymer solution for the binder was prepared with a solid content concentration of 10% by weight.

[0159] [Example 2] A polyamide copolymer solution for the binder was prepared in the same manner as in Example 1, except that the molar ratio of bis[4-(4-aminophenoxy)phenyl]sulfone to 4,4'-oxydianiline was changed to 5:5.

[0160] [Example 3] A polyamide copolymer solution for the binder was prepared in the same manner as in Example 1, except that the molar ratio of bis[4-(4-aminophenoxy)phenyl]sulfone to 4,4'-oxydianiline was changed to 3:7.

[0161] [Example 4] A polyamide copolymer solution for the binder was prepared in the same manner as in Example 1, except that the molar ratio of bis[4-(4-aminophenoxy)phenyl]sulfone to 4,4'-oxydianiline was changed to 1:9.

[0162] [Example 5] In a 500 ml four-necked flask under a nitrogen atmosphere, N-methyl-2-pyrrolidone (NMP), the monomers 3,4'-methylenedianiline (3,4'-MDA) and (bis[4-(4-aminophenoxy)phenyl]sulfone (BAPS), which form monomer units containing an ether group, and the monomer 5,5'-methylenebis(2-aminobenzoic acid) (MBAA), which contains a carboxylic acid, were added and stirred.

[0163] The amount of MBAA was fixed at 5 mol% relative to 100 mol% of the total molars of the polyamide copolymer used as a binder, and the molar ratio of bis[4-(4-aminophenoxy)phenyl]sulfone to 3,4'-methylenedianiline was 7:3.

[0164] Subsequently, after lowering the internal temperature of the reactor to below 5°C, isophthaloyl chloride (IPC), a monomer unit containing an aromatic ring, was added and the reaction was carried out.

[0165] To this, terephthaloyl chloride (TPC), a monomer that forms monomeric units containing aromatic rings, was added and the mixture was stirred for a sufficient amount of time.

[0166] The molar ratio of isophthaloyl chloride to terephthaloyl chloride was 3:7.

[0167] An olefin-based neutralizing agent was added to the solution after its viscosity had increased to a certain level, and the mixture was stirred to remove the HCl generated during the synthesis process.

[0168] Finally, a polyamide copolymer solution for the binder was prepared with a solid content concentration of 10% by weight.

[0169] [Example 6] A polyamide copolymer solution for the binder was prepared in the same manner as in Example 5, except that the molar ratio of bis[4-(4-aminophenoxy)phenyl]sulfone to 3,4'-methylenedianiline was changed to 5:5.

[0170] [Example 7] A polyamide copolymer solution for the binder was prepared in the same manner as in Example 5, except that the molar ratio of bis[4-(4-aminophenoxy)phenyl]sulfone to 3,4'-methylenedianiline was changed to 3:7.

[0171] [Example 8] A polyamide copolymer solution for the binder was prepared in the same manner as in Example 5, except that the molar ratio of bis[4-(4-aminophenoxy)phenyl]sulfone to 3,4'-methylenedianiline was changed to 1:9.

[0172] [Example 9] N-methyl-2-pyrrolidone (NMP), the monomers 1,3-bis(3-aminophenoxy)benzene (APB) and (bis[4-(4-aminophenoxy)phenyl]sulfone (BAPS), which form monomer units containing an ether group, and the monomer 5,5'-methylenebis(2-aminobenzoic acid) (MBAA), which contains a carboxylic acid, were added to a 500 ml four-necked flask under a nitrogen atmosphere and stirred.

[0173] The amount of MBAA was fixed at 5 mol% based on 100 mol% of the total molars of the binder polyamide copolymer, and the molar ratio of bis[4-(4-aminophenoxy)phenyl]sulfone to 1,3-bis(3-aminophenoxy)benzene was 7:3.

[0174] Subsequently, after lowering the internal temperature of the reactor to below 5°C, isophthaloyl chloride (IPC), a monomer unit containing an aromatic ring, was added and the reaction was carried out.

[0175] To this, terephthaloyl chloride (TPC), a monomer that forms monomeric units containing aromatic rings, was added and the mixture was stirred for a sufficient amount of time.

[0176] The molar ratio of isophthaloyl chloride to terephthaloyl chloride was 3:7.

[0177] An olefin-based neutralizing agent was added to the solution after its viscosity had increased to a certain level, and the mixture was stirred to remove the HCl generated during the synthesis process.

[0178] Finally, a polyamide copolymer solution for the binder was prepared with a solid content concentration of 10% by weight.

[0179] [Example 10] A polyamide copolymer solution for the binder was prepared in the same manner as in Example 9, except that the molar ratio of bis[4-(4-aminophenoxy)phenyl]sulfone to 1,3-bis(3-aminophenoxy)benzene was changed to 5:5.

[0180] [Example 11] A polyamide copolymer solution for the binder was prepared in the same manner as in Example 9, except that the molar ratio of bis[4-(4-aminophenoxy)phenyl]sulfone to 1,3-bis(3-aminophenoxy)benzene was changed to 3:7.

[0181] [Example 12] A polyamide copolymer solution for the binder was prepared in the same manner as in Example 9, except that the molar ratio of bis[4-(4-aminophenoxy)phenyl]sulfone to 1,3-bis(3-aminophenoxy)benzene was changed to 2:8.

[0182] [Comparative Example 1] A polyamide copolymer solution for the binder was prepared in the same manner as in Example 1, except that 4,4'-oxydianiline was not added (the molar ratio of bis[4-(4-aminophenoxy)phenyl]sulfone to 4,4'-oxydianiline was 10:0).

[0183] The monomer compositions of Examples 1-12 and Comparative Example 1, along with the molar ratios of BAPS to ODA, BAPS to 3,4'-MDA, and BAPS to APB, are shown in Table 1 below.

[0184] [Table 1]

[0185] Manufacturing Example 2. Manufacturing of Cathode Slurry and Cathode A cathode active material slurry composition with a solid content of 65% by weight was prepared by mixing 97.5% by weight of NCM811 as the electrode active material, 1.5% by weight of the binder polymer from Examples 1-12 and Comparative Example 1, 1% by weight of the CNT dispersion, and the remainder of NMP.

[0186] Specifically, a cathode active material slurry composition with a solid content of 65% by weight was prepared by using NCM811 as the electrode active material (97.5% by weight), the binder polymers from Examples 1-12 and Comparative Example 1 (1.5% by weight), a CNT dispersion (1% by weight), and the remaining portion as NMP.

[0187] On the other hand, the positive electrode active material slurry composition may contain 96% to 98% by weight of the electrode active material, 1.5% to 2% by weight of the binder polymer, and 0.7% to 0.8% by weight of a CNT dispersion. Furthermore, the solid content of the positive electrode active material slurry composition may be 60% to 70% by weight.

[0188] The manufactured positive electrode slurry composition was coated onto a 20 μm thick aluminum (Al) foil, which is a positive electrode current collector, using an applicator. After drying in a circulating oven at 110°C for 1 hour, the dried positive electrode was rolled using a roll press to produce the positive electrode.

[0189] Manufacturing Example 3. Cell Manufacturing A non-aqueous electrolyte containing 1% by weight of 1M LiPF6 and FEC (Fluoro Ethylene Carbonate), 1% by weight of PS (Propylene Sulfite), and 1% by weight of LiPO2F2 was used as the electrolyte. A polyolefin separation membrane was interposed between the positive electrode and the negative electrode, using positive electrode plates made from the binder polymers of Examples 1 to 12 and Comparative Example 1, which were produced according to Production Example 2, and a 2032 coin cell type lithium secondary battery was manufactured without distinction of form.

[0190] Evaluation Example 1: Measurement of Bonding Force The positive electrode produced according to Production Example 2 was dried at 130°C for 1 hour, and then cut into pieces measuring 15 x 2.5 cm.

[0191] Subsequently, the coated side of the positive electrode was attached to an acrylic plate with double-sided tape, and then pressed 3-4 times with a pressure-applying rubber roller to produce a peel-off test sample.

[0192] The prepared samples were loaded onto a UTM capable of measuring adhesive strength, and a 2.5 cm 180° peel test was conducted. The load value (gf / 25 mm) was measured, and the bonding strength of the positive electrode was calculated.

[0193] The calculated bonding force of the positive electrode is shown in Table 2 below.

[0194] [Table 2]

[0195] As shown in Table 2 above, the binder polymers of Examples 1 to 12 exhibited a binding strength of 90.59 gf / 25 mm or higher.

[0196] It was confirmed that the binder polymers of Examples 1 to 12 exhibited significantly improved binding strength compared to the polyamide binder polymer of Comparative Example 1, which did not use ODA as a monomer.

[0197] On the other hand, it was confirmed that the binder polymers of Examples 1 to 4 showed improved cathode binding strength as the ODA content increased in the molar ratio of BAPS to ODA (mol% of BAPS:mol% of ODA).

[0198] Furthermore, it was confirmed that the binder polymers of Examples 5 to 8 showed improved cathode binding strength as the 3,4'-MDA content increased in the molar ratio of BAPS to 3,4'-MDA (mol% of BAPS:mol% of 3,4'-MDA).

[0199] In addition, it was confirmed that the binder polymers of Examples 9 to 12 showed improved cathode binding strength as the APB content increased in the molar ratio of BAPS to APB (mol% of BAPS:mol% of APB).

[0200] As a result, it was confirmed that the binder of this application, which contains a polyamide polymer in which the molar ratio of BAPS to ODA, the molar ratio of BAPS to 3,4'-MDA, and the molar ratio of BAPS to APB were appropriately adjusted, has excellent binding strength properties.

[0201] Evaluation Example 2: Measurement of Battery Performance Cells manufactured according to Manufacturing Example 3 using positive electrode plates with binder polymers from Examples 1-12 and Comparative Example 1 were charged to 4.2V at a rate of 0.1C in CC / CV mode, then discharged to 2.8V at a rate of 0.1C, then charged to 4.2V at a rate of 0.2C, then discharged to 2.8V at a rate of 0.2C, then charged to 4.2V at a rate of 0.5C, then discharged to 2.8V at a rate of 0.5C (initial formation). At this time, the chamber temperature was 25°C. The "C" above represents the cell discharge rate, which is the value obtained by dividing the total capacity of the cell by the total discharge time.

[0202] The initial discharge capacity and initial efficiency of cells manufactured according to Manufacturing Example 3 using positive electrode plates made with the binder polymers of Examples 1 to 12 and Comparative Example 1 are shown in Table 3 below.

[0203] During the initial formation, the discharge capacity during discharge at a rate of 0.1C up to 2.8V was measured as the initial discharge capacity, and the initial efficiency was calculated using the following formula 3.

number

[0204] [Table 3]

[0205] As shown in Table 3 above, the cells manufactured by Manufacturing Example 3 using the cathode plates made from the binder polymers of Examples 1 to 12 showed an initial discharge capacity of 196.01 mAh / g or higher and an initial efficiency of 87.15% or higher.

[0206] When comparing the cells produced by Manufacturing Example 3 using the positive electrode plates of the binder polymers from Examples 1 to 12 with the cells produced by Manufacturing Example 3 using the positive electrode plates of the polyamide binder polymer from Comparative Example 1, which does not use ODA as a monomer, it was confirmed that the initial discharge capacity and initial efficiency were all equivalent or improved.

[0207] Furthermore, when an electrode binder containing the polyamide polymer of the present application (Examples 1-12) is applied, the improved binding characteristics compared to when an electrode binder containing the polymer of Comparative Example 1 is applied prevent electrode detachment due to lithium ion movement, and it is presumed that this improves the electrochemical properties of the secondary battery.

[0208] Evaluation Example 3. Measurement of DC-IR Resistance Cells manufactured according to Manufacturing Example 3 using positive electrode plates containing the binder polymers of Examples 1-12 and Comparative Example 1 were charged to 4.2V at a 1C rate in CC / CV mode and then discharged to 2.8V at a 1C rate.

[0209] The DC-IR resistance value was measured when a battery that had been discharged reached a State of Charge (SoC) of 50%.

[0210] At this time, the chamber temperature was 25°C. The aforementioned "C" represents the cell discharge rate, which is the value obtained by dividing the total capacity of the cell by the total discharge time.

[0211] The measurement results of the DC-IR resistance values ​​of cells manufactured according to Manufacturing Example 3 using positive electrode plates made with the binder polymers of Examples 1 to 12 and Comparative Example 1 are shown in Table 4 below.

[0212] [Table 4]

[0213] As shown in Table 4 above, the DC-IR resistance of the cell manufactured by Manufacturing Example 3 using the positive electrode plate with the binder polymers of Examples 1 to 12 was 23.1 mΩ or less.

[0214] In particular, the DC-IR resistance of the cells manufactured according to Manufacturing Example 3 using the positive electrode plates made with the binder polymers of Examples 5 to 12 showed a resistance of 19.4 mΩ or less.

[0215] In other words, it was confirmed that the cells produced by Manufacturing Example 3 using the positive electrode plates of the binder polymers of Examples 5 to 12 had lower resistance values ​​compared to the cells produced by Manufacturing Example 3 using the positive electrode plates of the polyamide binder polymer of Comparative Example 1, which does not use ODA as a monomer.

[0216] Furthermore, it was confirmed that the cells produced by Manufacturing Example 3 using the positive electrode plates of the binder polymers of Examples 1 to 4 exhibited resistance values ​​equivalent to those of the cells produced by Manufacturing Example 3 using the positive electrode plates of the polyamide binder polymer of Comparative Example 1, which does not use ODA as a monomer.

[0217] Evaluation Example 4. Measurement of Battery Capacity Retention Rate The charge / discharge and chamber temperature conditions were set for analyzing the cycle stability of cells manufactured according to Manufacturing Example 3 using cathode plates made with binder polymers from Examples 1-12 and Comparative Example 1.

[0218] The battery was charged to 4.2V at a 1C rate in CC / CV mode, and then discharged to 2.8V at a 1C rate. At this time, the chamber temperature was 25°C. The "C" in the above definition represents the cell discharge rate, which is the value obtained by dividing the total capacity of the cell by the total discharge time.

[0219] The battery was charged and discharged under these set conditions to conduct a cycle analysis. Each cycle consisted of one charge and one discharge, and a total of 100 cycles were performed. After 100 cycles were completed, the battery capacity was measured compared to the initial capacity (capacity at the first cycle) to confirm how well the battery capacity was maintained as the cycles progressed.

[0220] The measurement results of the capacity retention rate of cells manufactured by Manufacturing Example 3 using cathode plates containing the binder polymers of Examples 1 to 12 and Comparative Example 1 are shown in Table 5 below.

[0221] The battery capacity retention rate after 100 cycles was calculated using the following formula 4.

number

[0222] [Table 5]

[0223] As shown in Table 5 above, the cells manufactured by Manufacturing Example 3 using the cathode plates containing the binder polymers of Examples 1 to 12 showed a capacity retention rate of 96.33% or higher.

[0224] It was confirmed that the cells produced by Production Example 3 using the cathode plates of the binder polymers of Examples 1 to 12 exhibited a capacity retention rate equivalent to or better than that of the cells produced by Production Example 3 using the cathode plates of the polyamide binder polymer of Comparative Example 1, which does not use ODA as a monomer.

[0225] The measurement results for battery capacity retention show a similar trend to those for DC-IR resistance, suggesting that the reduction in DC-IR resistance has a positive effect on battery capacity retention.

[0226] As a result, it was confirmed that the binder of the present invention, which contains a polyamide polymer in which the molar ratio of BAPS to ODA, the molar ratio of BAPS to 3,4'-MDA, and the molar ratio of BAPS to APB are appropriately adjusted, has an excellent effect of improving resistance within the battery and improving the battery's capacity retention rate.

[0227] Furthermore, we were able to confirm that the characteristics of the secondary battery are improved when the binder containing the polyamide polymer of this application is applied.

[0228] The scope of the present invention is defined by the claims set forth below rather than by the detailed description above, and all modifications or altered forms derived from the meaning and scope of the claims and the concept of equivalents thereof should be interpreted as being included within the scope of the present invention.

Claims

1. A first monomer unit comprising an ether group, a linear or branched hydrocarbon group having 1 to 10 carbon atoms, or a combination thereof, Polyamide polymer.

2. The first monomer unit includes a structure represented by the following chemical formula 1, which comprises two aromatic rings linked to each other by linear or branched hydrocarbons having 1 to 10 carbon atoms. The polyamide polymer according to claim 1. 【Chemistry 1】 R 1 and R 2 Each is independently hydrogen; or a linear or branched hydrocarbon having 1 to 4 carbon atoms; m is between 1 and 4.

3. The first monomer unit is formed by polymerization of the first monomer represented by the following chemical formula 2. The polyamide polymer according to claim 1. 【Chemistry 2】 In the aforementioned chemical formula 2, a + b + c is between 1 and 10, X 1 , X 2 , and X 3 Each of these is independently an oxygen atom; or a linear or branched hydrocarbon having 1 to 10 carbon atoms.

4. The first monomer is 4,4'-oxydianiline (ODA), 3,4'-methylenedianiline (MDA), 1,3-bis(3-aminophenoxy)benzene (APB), 1,4-bis(4-aminophenoxy)benzene (APB), 1,3-bis(4-aminophenoxy)benzene (APB), 1,3-bis(4-aminophenoxy)benzene (APB), 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene (1,3-Bis[2- (4-aminophenyl)-2-propyl]benzene), 4,4'-diaminodiphenylmethane (4,4'-Diaminodiphenylmethane), 4,4'-diaminodiphenylethane (4,4'-Diaminodiphenylethane), 4,4'-isopropylidenebis[(4-aminophenoxy)benzene] (4,4'-Isopropylidenebis[(4-aminophenyl)benzene]), 4,4'-(1,4-phenylenediisopropylidene)bisaniline (4,4'-(1,4-phenylenediisopropylidene)bisaniline), or combinations thereof. The polyamide polymer according to claim 3.

5. It further comprises a second monomer unit containing at least one aromatic ring, The polyamide polymer according to claim 1.

6. A third monomer unit containing a sulfone, a fourth monomer unit containing a carboxylic acid, or a combination thereof, is additionally included. The polyamide polymer according to claim 1.

7. The second monomer unit formed by polymerization is a terephthaloyl chloride monomer, an isophthaloyl chloride monomer, a phthalic acid monomer, an isophthalic acid monomer, a terephthalic acid monomer, or a combination thereof. The polyamide polymer according to claim 5.

8. The third monomer formed by polymerization of the third monomer unit is bis[4-(4-aminophenoxy)phenylsulfone (bis[4-(4-aminophenoxy)phenyl]sulfone)), bis(4-aminophenyl)sulfone (bis(4-aminophenyl)sulfone), bis(3-aminophenyl)sulfone (bis(3-aminophenyl)sulf 1,3-(3-aminophenylsulfone), 3,3'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 1,3-bis(3-aminophenylsulfone)benzene (1,3-bis (3-aminophenyl)sulfone), 1,3-bis(4-aminophenylsulfone)benzene (1,3-bis(4-aminophenyl)sulfone), 1,4-bis(4-aminophenylsulfone)benzene (1,4-bis(4-aminophenyl)sulfone), bis[3-(3-aminophenoxy)phenylsulfone (bis[3-(3- (aminophenoxy)phenyl sulfone)), bis[3-(4-aminophenoxy)phenyl sulfone (bis[3-(4-aminophenoxy)phenyl sulfone)), bis[4-(3-aminophenoxy)phenyl sulfone (bis[4-(3-aminophenoxy)phenyl sulfone)), or a combination thereof, The polyamide polymer according to claim 6.

9. The fourth monomer unit formed by polymerization is 5,5'-methylenebis(2-aminobenzoic acid, MBAA), 3,5-diaminobenzoic acid (DABA), or a combination thereof. The polyamide polymer according to claim 6.

10. Based on a total content of 100 mol% of the third monomer unit and the first monomer unit, the molar ratio of the third monomer unit to the first monomer unit (mol% of the third monomer unit: mol% of the first monomer unit) is 90:10 to 1:

99. The polyamide polymer according to claim 6.

11. The aforementioned polyamide polymer contains repeating monomer units represented by the following chemical formula 3, 【Transformation 3】 In the aforementioned chemical formula 3, Y 1 It comprises a halogen element, hydrogen, a hydroxyl group, a carboxyl group, a linear or branched hydrocarbon group having 1 to 4 carbon atoms, or a combination thereof, and includes at least one aromatic ring. Y 2 Ha-SO 2 Two aromatic rings linked to each other by -; An aromatic ring substituted with at least one carboxyl group; Two aromatic rings linked to each other by an oxygen atom or a linear or branched hydrocarbon having 1 to 10 carbon atoms; or a combination thereof, The foregoing -SO 2 Two aromatic rings linked to each other by - may be substituted with a halogen element, hydrogen, a hydroxyl group, a carboxyl group, a linear or branched hydrocarbon group having 1 to 4 carbon atoms in which the halogen element is substituted or unsubstituted, or a combination thereof, or c + d = 1. The polyamide polymer according to claim 1. (However, the above Y 2 It must contain two aromatic rings linked to each other by an oxygen atom or a linear or branched hydrocarbon having 1 to 10 carbon atoms.

12. A polyamide polymer comprising the polyamide polymer according to any one of claims 1 to 11, binder.

13. The binder according to claim 12, Electrode active material and, slurry.

14. Current collector and, The electrode active material layer, plain portion insulating coating layer, or a combination thereof, formed on the current collector, includes the binder described in claim 12, electrode.

15. A porous substrate coated with a slurry composition containing the binder described in claim 12, Separation membrane.

16. A binder including the one described in claim 12, Slurry composition for insulating coating layer of plain portion of secondary battery.

17. A binder including the one described in claim 12, Secondary battery.

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