Binder composition for secondary batteries

Abstract

This invention is measured according to the ISO 9277 method for 4m 2 / g or less, preferably 2m 2 The present invention relates to an electrode-forming composition comprising a tetrafluoroethylene (TFE)(co)polymer having a specific surface area of ​​less than or equal to / g, at least one electroactive substance, optionally at least one solid ion-conducting inorganic material, and optionally at least one processing aid; a separator-forming composition comprising the TFE(co)polymer, at least one solid ion-conducting inorganic material, and optionally at least one processing aid; a method for producing an electrode or separator using the composition; and an electrode or separator obtained by the method. The present invention also relates to a method for producing a gel polymer electrode; a gel polymer electrode obtained by the method; a secondary battery comprising an electrode, separator, or gel polymer electrode according to the present invention; and the use of the TFE(co)polymer in a binder composition for a secondary battery.

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims priority under European Patent Application No. 23155379.3, filed on 7 February 2023, and the entirety of this application is incorporated herein by reference for any purpose.

[0002] This invention is measured according to the ISO 9277 method for 4m 2 / g or less, preferably 2m 2 The present invention relates to an electrode-forming composition comprising a tetrafluoroethylene (TFE)(co)polymer having a specific surface area of ​​less than or equal to / g, at least one electroactive substance, optionally at least one solid ion-conducting inorganic material, and optionally at least one processing aid; a separator-forming composition comprising a TFE(co)polymer, at least one solid ion-conducting inorganic material, and optionally at least one processing aid; a method for producing an electrode or separator using the composition; and an electrode or separator obtained by the method. The present invention also relates to a method for producing a gel polymer electrode; a gel polymer electrode obtained by the method; a secondary battery comprising an electrode, separator, or gel polymer electrode according to the present invention; and the use of TFE(co)polymer in a binder composition for a secondary battery. [Background technology]

[0003] The polymerization of TFE proceeds via a free radical mechanism initiated by a catalyst or initiator depending on the reaction temperature, producing polytetrafluoroethylene (PTFE).

[0004] Dry processes for manufacturing electrodes have been developed to reduce the drying step, which is time-consuming and costly but essential in wet processes. Typically, such dry processes rely on the fibrillation properties of certain fluoropolymers, such as PTFE, which are particularly inert and stable in conventional electrolyte solvents for secondary batteries. Therefore, the stability of electrodes manufactured using PTFE can be higher than that of electrodes manufactured using other binders.

[0005] In this field, two different polymerization methods, namely suspension polymerization and emulsion polymerization, are well known for the production of two different types of PTFE.

[0006] Suspension polymerization is a method for producing granular polymers by polymerizing TFE in an aqueous solution while vigorously stirring without the use of surfactants. In contrast, emulsion polymerization produces PTFE in the form of a colloidal dispersion under high temperature and pressure using a sufficient amount of surfactant while gently stirring, and then coagulates this colloidal dispersion to produce PTFE fine powder that is distinct from the granular PTFE produced by suspension polymerization.

[0007] Due to its excellent fibrillation behavior and ease of fibrillation, emulsion-polymerized PTFE has traditionally been used in dry processes for electrode manufacturing. However, emulsion-polymerized PTFE has several drawbacks, including difficulty in handling, and requires low temperatures during storage and throughout transport to avoid premature fibrillation. Furthermore, the relatively large particle size of emulsion-polymerized PTFE negatively affects the uniformity of the resulting compound.

[0008] Furthermore, due to the presence of residual surfactants, their use should be avoided. In particular, the surfactants selected in the synthesis of fluoropolymers are generally fully fluorinated surfactants or partially fluorinated surfactants.

[0009] In this regard, methods for preparing fluoropolymers, particularly PTFE, in aqueous media using non-fluorinated hydrocarbon surfactants have been reported, for example, in International Publication No. 2022 / 072693 (Chemours FC, LLC) and International Publication No. 2021 / 070159 (Gujarat Fluorochemicals Limited). However, their performance is known to be inferior to that of emulsion-polymerized PTFE produced using fluorine-containing surfactants. In addition, the problem of residual hydrocarbon surfactants remains. Furthermore, as mentioned above, handling such fine powders requires special treatment, namely low-temperature control throughout storage and transportation.

[0010] For example, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) are two fluorine-containing surfactants that were widely used in the past. While such fluorine-containing surfactants are better at lowering the surface tension of water than equivalent hydrocarbon-based surfactants, they persist and accumulate in the environment for long periods, and are therefore detected in humans and wildlife.

[0011] Since 2009, PFOS and its derivatives have been included in the international Stockholm Convention for the elimination of their use. Subsequently, PFOS is restricted in Annex 1 of the EU's Persistent Organic Pollutants (POPs) Regulation. Furthermore, the Stockholm Convention mandates the global elimination of PFOA, its salts, and PFOA-related compounds. In Europe, PFOA has also been banned under the POPs Regulation since July 4, 2020. In addition, perfluorohexanesulfonic acid (PFHxS), its salts, and PFHxS-related compounds are being considered for inclusion in the Stockholm Convention.

[0012] In parallel, the manufacture and use of some PFAS are restricted under the Register, Evaluation, Authorization and Restriction of Chemicals, i.e., REACH.

[0013] On the other hand, suspension-polymerized PTFE has a relatively small particle size compared to emulsion-polymerized PTFE, and is easy to handle with no particular restrictions on storage and transportation. In particular, suspension polymerization can be carried out under conditions that are substantially free of fluorine-based or hydrocarbon-based surfactants.

[0014] The applicant has surprisingly found that TFE(co)polymers produced by suspension polymerization can be used as binders for secondary batteries because they can be at least partially fibrillated while retaining excellent performance. Therefore, electrodes and / or separators produced by using the TFE(co)polymer are substantially free of fluorine-containing surfactants. Even if fluorine-containing surfactants may be detected due to their ubiquitous presence in the environment, their detection can be controlled to very low levels relative to the total mass of the electrode or separator, for example, 100 parts per billion (ppb), preferably 20 ppb, and more preferably 2 ppb. [Overview of the project]

[0015] The first object of the present invention is 4m measured according to the ISO9277 method. 2 / g or less, preferably 2m 2 The electrode-forming composition comprises a binder composition containing a tetrafluoroethylene (TFE)(co)polymer having a specific surface area of ​​less than or equal to / g, at least one electroactive substance, optionally at least one solid ion-conducting inorganic material, and optionally at least one processing aid.

[0016] A second object of the present invention is a separator-forming composition comprising the binder composition according to the present invention, at least one solid ion-conducting inorganic material, and optionally at least one processing aid.

[0017] A third object of the present invention is a method for manufacturing an electrode or separator using the electrode-forming composition or separator-forming composition according to the present invention.

[0018] A fourth object of the present invention is an electrode or separator obtained by the method according to the present invention.

[0019] A fifth object of the present invention is a method for producing a gel polymer electrode using the binder composition according to the present invention.

[0020] A sixth object of the present invention is a gel polymer electrode obtained by the method according to the present invention.

[0021] A seventh object of the present invention is a secondary battery comprising an electrode, separator, or gel polymer electrode according to the present invention.

[0022] Another object of the present invention is 4m measured according to the ISO9277 method 2 / g or less, preferably 2m 2 This involves the use of TFE(co)polymers having a specific surface area of ​​less than / g in binder compositions for secondary batteries.

[0023] The inventors have surprisingly found that TFE(co)polymers produced by suspension polymerization can provide a particularly advantageous combination of properties, namely sufficient fibrillation properties to enable a dry manufacturing process for electrodes and / or separators for secondary batteries, without impairing battery performance and mechanical properties. In addition to this advantage, the fact that fluorine-containing surfactants are not required in the production of TFE(co)polymers adds value in addressing problems associated with fluorine-containing surfactants, namely persistence in ecosystems and bioaccumulation in humans and animals. [Modes for carrying out the invention]

[0024] Ratios, concentrations, amounts, and other numerical data may be presented herein in a range format. Such range formats are used merely for convenience and brevity and are to be construed flexibly as encompassing not only the numerical values explicitly recited as the upper and lower limits of the range but also all the individual numerical values or sub-ranges subsumed within that range as if each were explicitly recited. In the context of the present invention, the term "weight percent" (wt%) indicates the content of a particular component in a mixture, calculated as the ratio between the weight of the component and the total weight of the mixture.

[0025] It should be understood that both the foregoing summary and the following detailed description are exemplary and intended to provide further explanation of the invention as claimed. Accordingly, various changes and modifications described herein will be apparent to those skilled in the art. Additionally, descriptions of well-known functions and structures may be omitted for clarity and brevity.

[0026] The present invention provides an electrode-forming composition comprising a TFE (co)polymer having a specific surface area of 4 m 2 / g or less, preferably 2 m 2 / g or less, measured according to the ISO9277 method, at least one electroactive material, optionally at least one solid ion-conductive inorganic material, and optionally at least one processing aid.

[0027] In contrast, the specific surface area of an emulsion-polymerized TFE (co)polymer is usually 5 m 2 / g or more, preferably 6.5 m 2 / g or more, more preferably 8.0 m 2 / g or more, when measured according to the ISO9277 method.

[0028] In some embodiments, the TFE(co)polymer of the present invention is polymerized by a suspension polymerization process in an aqueous medium with vigorous stirring at a high pressure, for example, 0.3 to 2.8 MPa, and at a moderate temperature, for example, 40°C to 90°C. Inorganic radical initiators such as ammonium persulfate, potassium persulfate, and potassium permanganate can be used in the suspension polymerization process. Typically, the TFE(co)polymer extracted from the polymerization reactor is in the form of irregular filamentous particles, so post-processing steps such as dehydration, drying, and grinding can be performed to prepare a powdery fine-grained suspension TFE(co)polymer having a predetermined particle size, for example, 10 μm to 100 μm, typically 15 μm to 40 μm.

[0029] For the purposes of this invention, the term "secondary battery" is intended to mean a rechargeable battery.

[0030] In one embodiment, the TFE(co)polymer is a TFE homopolymer, a TFE copolymer, or a blend thereof.

[0031] In certain embodiments, the TFE copolymer is - C2-C8 perfluoroolefins other than TFE, such as hexafluoropropylene (HFP); - Hydrogen-containing C2-C8 fluoroolefins such as vinyl fluoride (VF), trifluoroethylene (TrFE), and hexafluoroisobutylene; - Formula CH2=CH-R f (In the formula, R f (Per)fluoroalkylethylenes are C1-C6 (per)fluoroalkyl groups; - Formula CF2=CFOR f (In the formula, R f (PAVE) is a (per)fluoroalkyl vinyl ether (C1-C6 (per)fluoroalkyl group); - Equation CF2 = CFOX (where X is C1~C containing at least one catenary oxygen atom) 12 (per)fluorooxyalkyl vinyl ether (which is a per)fluorooxyalkyl; - Formula: [ka] (In the formula, R is equal to or different from each other) f3 , R f4 , R f5 , and R f6 (These are independently selected from C1-C6 (per)fluoroalkyl groups, which optionally contain a fluorine atom and at least one oxygen atom.) (Per)fluorodioxole containing; - Formula CFX2=CX2OCF2OR” f (In the formula, R” f X2 is selected from linear or branched C1-C6 (per)fluoroalkyl groups, C5-C6 cyclic (per)fluoroalkyl groups, and linear or branched C2-C6 (per)fluorooxyalkyl groups containing 1-3 catenary oxygen atoms, where X2 is F or H; preferably R. f (MOVE) is a (per)fluoroalkoxy vinyl ether (MOVE) of -CF2CF3(MOVE1), -CF2CF2OCF3(MOVE2), or -CF3(MOVE3), where X2 is F; Includes additional repeating units derived from.

[0032] In a more specific embodiment, the TFE copolymer contains 5 mol% or less, preferably 1 mol% or less of the additional repeating units, relative to the total number of moles of repeating units of the TFE copolymer.

[0033] In another specific embodiment, the binder composition further comprises an additional polymer different from the TFE(co)polymer.

[0034] In a more specific embodiment, the additional polymer, distinct from the TFE(co)polymer, is nonionic conductive.

[0035] Non-limiting examples of additional polymers different from TFE(co)polymers include (alkyl)acrylate polymers, styrene(alkyl)acrylate copolymers, polyvinylpyrrolidone (PVP)(co)polymers, diene or olefin-based rubbers, such as isobutylene isoprene rubber (IIR, also known as butyl rubber), butadiene rubber (BR), isoprene rubber (IR), ethylene-propylene-diene monomer rubber (EPDM), styrene-butadiene rubber (SBR), styrene-ethylene-butylene-styrene copolymer (SEBS), nitrile butadiene rubber (NBR), hydrogenated NBR (hNBR), and These include (co)polymers based on modified polysaccharides such as ethylene-propylene rubber, for example, carboxymethylcellulose (CMC), polyamide (PA), polyaryletherketone (PAEK) (co)polymers, for example, polyetheretherketone (PEEK), polyamideimide (PAI), perfluoroalkoxyalkane (PFA), poly(acrylonitrile) (PAN), styrene-acrylonitrile rubber (SAN), and vinyl alcohol or vinyl acetate-containing (co)polymers, for example, polyvinyl alcohol (PVOH), polyvinyl acetate (PVA), and polybutyrate vinyl (PVB).

[0036] In another specific embodiment, the additional polymer, distinct from the TFE(co)polymer, is a vinylidene difluoride (VDF)-based(co)polymer.

[0037] In a preferred embodiment, the VDF-based (co)polymer contains at least 50 mol%, preferably at least 60 mol%, of VDF-derived repeating units relative to the total repeating units of the VDF-based (co)polymer.

[0038] In a more preferred embodiment, the VDF-based (co)polymer further comprises repeating units derived from at least one comonomer different from VDF.

[0039] In certain embodiments, repeating units derived from at least one comonomer different from VDF include: - Formula: [ka] (In the formula, each of R1, R2, and R3 is either equal to or different from each other, and independently is a hydrogen atom or a C1-C3 hydrocarbon group, R OH (This refers to a hydroxyl group, or a C1-C5 hydrocarbon moiety containing at least one hydroxyl group.) Hydrophilic (meth)acrylic copolymer; - C2-C8 perfluoroolefins such as tetrafluoroethylene (TFE) and hexafluoropropylene (HFP); - Chloro-, and / or bromo-, and / or iodo-C2~C6 fluoroolefins such as chlorotrifluoroethylene (CTFE); - Formula CF2=CFOR f (In the formula, R f (PAVE) is a (per)fluoroalkyl vinyl ether (C1-C6 (per)fluoroalkyl group); - Fluorinated olefin comonomers comprising at least one -SO2X functional group (where X is selected from X' and OM, X' is selected from the group consisting of F, Cl, Br, and I, and M is selected from the group consisting of H, alkali metals, and NH4); It is selected from the group consisting of the following.

[0040] Hydrophilic (meth)acrylic copolymers are preferably of the formula: [ka] (In the formula, R1, R2, R OH Each of them has the meaning defined above, and R3 is hydrogen; more preferably, each of R1, R2, and R3 is hydrogen, while R OH (This has the same meaning as detailed above.) Follow the rules.

[0041] Non-limiting examples of hydrophilic (meth)acrylic comonomers include, in particular, acrylic acid, methacrylic acid, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxyethylhexyl (meth)acrylate.

[0042] Hydrophilic (meth)acrylic comonomers are more preferably the following: - Formula: [ka] Hydroxyethyl acrylate (HEA), - Formula: [ka] Any of the following 2-hydroxypropyl acrylates (HPA), - Formula: [ka] Acrylic acid (AA), and - those mixtures It is selected from the group consisting of the following.

[0043] More preferably, the hydrophilic (meth)acrylic comonomer is AA and / or HEA, and most preferably AA.

[0044] A fluorinated olefin comonomer containing at least one -SO2X functional group is preferably, - Equation: CF2 = CF(CF2) p SO2X' (In the formula, p is an integer between 0 and 10, preferably between 1 and 6, more preferably p is equal to 2 or 3, and preferably X' = F) sulfonyl halide fluoroolefins; - Equation: CF2 = CF - O - (CF2) m SO2X' (In the formula, m is an integer between 1 and 10, preferably between 1 and 6, more preferably between 2 and 4, and even more preferably m is equal to 2, and preferably X' = F) sulfonyl halide fluorovinyl ethers; - Equation: CF2 = CF - (OCF2CF(R F1 )) w -O-CF2(CF(R F2 )) y SO2X' (In the formula, w is an integer between 0 and 2, and R F1 and R F2 C1-C are either equal to or different from each other and may be independently optionally substituted with F, Cl, or one or more ether oxygen atoms. 10 It is a fluoroalkyl group, where y is an integer from 0 to 6; preferably w is 1, R F1 is -CF3, y is 1, R F2 (where is F, and preferably X'=F) sulfonyl halide fluoroalkoxy vinyl ethers; - Formula CF2=CF-Ar-SO2X' or CF2=CF-O-Ar-SO2X' (In the formula, Ar is C5~C) 15 Sulfonyl halide aromatic fluoroolefins having an aromatic substituent or heteroaromatic substituent, preferably X'=F; It is selected from the group consisting of the following.

[0045] In a more preferred embodiment, the fluorinated olefin comonomer containing at least one SO2X functional group is selected from the group consisting of sulfonyl fluorides (i.e., X'=F). Most preferably, b) the fluorinated olefin monomer containing at least one -SO2X functional group is of the formula: CF2=CF-O-(CF2) m -SO2F (In the formula, m is an integer between 1 and 6, preferably between 2 and 4.) Selected from the group of sulfonyl fluorovinyl ethers.

[0046] In a more preferred embodiment, the fluorinated olefin comonomer containing at least one -SO2X functional group is perfluoro-5-sulfonylfluorido-3-oxa-1-pentene (CF2=CF-O-CF2CF2-SO2F).

[0047] In one embodiment, the TFE(co)polymer is characterized by its high molecular weight having a standard specific gravity of less than 2.200, preferably less than 2.190, and more preferably less than 2.180, as measured according to ASTM D792.

[0048] In the present invention, the term "electroactive material" is intended to mean a material that can incorporate or insert metal ions into its structure and substantially release them therefrom during the charging and discharging phases of a battery.

[0049] In one embodiment, the electroactive material is used for the positive electrode.

[0050] In another embodiment, the electroactive material is used for the negative electrode.

[0051] In certain embodiments, the metal ion is a lithium ion.

[0052] In the present invention, the solid ion-conducting inorganic material is not particularly limited as long as it can conduct metal ions within its structure.

[0053] In certain embodiments, the solid ion-conducting inorganic material is sulfide-based solid ion-conducting inorganic particles.

[0054] In the present invention, the term "sulfide-based solid ion-conducting inorganic particles" is not particularly limited as long as it is a solid electrolyte material containing sulfur atoms in its molecular structure or composition.

[0055] The sulfide-based solid ion-conducting inorganic particles preferably contain Li, S, and elements from groups 13 to 15 of the periodic table, such as P, Si, Sn, Ge, Al, As, Sb, or B, in order to increase lithium ion conductivity.

[0056] The sulfide-based solid ion-conducting inorganic particles according to the present invention are preferably selected from the group consisting of the following: - Li 10 SnP2S 12 Lithium tin sulfide ("LSPS") materials such as; - Formula (Li2S) x -(P2S5) y (In the equation, x+y=1 and 0≦x≦1), Li7P3S 11 Li7PS6, Li4P2S6, Li 9.6 P3S 12 and lithium phosphate sulfide ("LPS") materials such as glass, crystal or glass ceramics of Li3PS4; - Li2CuPS4, Li 1+2x Zn 1-x PS4 (in the formula, 0≦x≦1), Li 3.33 Mg 0.33 P2S6 and Li 4-3x Sc x Doped LPS such as P2S6 (where 0≦x≦1); - Formula Li x P y S z Lithium phosphorus sulfide oxygen ("LPSO") material of type O (wherein the formula is 0.33 ≤ x ≤ 0.67, 0.07 ≤ y ≤ 0.2, 0.4 ≤ z ≤ 0.55); - Li 10 SnP2S 12、 Li 10 GeP2S 12 Li 10 SiP2S 12 and lithium phosphide materials containing X such as Li2S-P2S5-SnS, where X is Si, Ge, Sn, As, or Al ("LXPS"); - Lithium phosphate oxygen ("LXPSO") containing X, where X is Si, Ge, Sn, As, or Al; - Li2SiS3, Li2S-P2S5-SiS2, Li2S-P2S5-SiS2-LiCl, Li2S-SiS2-P2S5, Li2S-SiS2-P2S5-LiI, Li2S-SiS2-LiI, Li2S-SiS2, Li 9.54 Si1.74 P 1.44 S 11.7 Cl 0.3 , and lithium silicon sulfide ("LSS") materials such as Li2S-SiS2-Al2S3; - Lithium boron sulfide materials such as Li3BS3 and Li2S-B2S3-LiI; - Li 0.8 Sn 0.8 S2, Li4SnS4, Li 3.833 Sn 0.833 As 0.166 Lithium tin sulfide materials and lithium arsenide materials such as S4, Li3AsS4-Li4SnS4, and Ge-substituted Li3AsS4; - Li4PS4Cl 、 Li7P2S8Cl and Li7P2S8I, etc., with the general formula Li a PS b X c Lithium phosphorus sulfide materials (wherein X represents at least one halogen element selected from the group consisting of Cl, Br and I or combinations thereof; a represents a number from 2.0 to 7.0, b represents a number from 3.5 to 6.0, and c represents a number from 0 to 3.0); and - A combination of those.

[0057] In a more preferred embodiment, the sulfide-based solid ion-conducting inorganic particles are those of the general formula Li a PS b X c The lithium phosphorus sulfide material is, more particularly, an argyrodite-type sulfide material of the formula Li6PS5X (wherein X is Cl, Br, or I).

[0058] In another preferred embodiment, the argyrodite-type sulfide material of formula Li6PS5Y is deficient in sulfur and / or lithium, for example, Li 0 ≤ x ≤ 0.5 6-x PS 5-x Cl 1+x or doped with heteroatoms.

[0059] Particularly preferred sulfide-based solid ion-conducting inorganic particles are lithium tin sulfide ("LSPS") materials (e.g., Li10 SnP2S 12 ) and an argyrodite-type sulfide material (e.g., Li6PS5Cl).

[0060] In another specific embodiment, the solid ion conductive inorganic material is an oxide-based solid ion conductive inorganic particle.

[0061] In the present invention, the term "oxide-based solid ion conductive inorganic particle" is not particularly limited as long as it is a solid electrolyte material containing oxygen atoms in its molecular structure or in the composition.

[0062] In one embodiment, the oxide-based solid ion conductive inorganic particle is a garnet-type inorganic particle.

[0063] As used herein, the term "garnet" refers to the atomic structure of a crystalline or partially crystalline oxide ceramic solid.

[0064] In a specific embodiment, the garnet-type inorganic particle is M 1 a M 2 b M 3 c O d (where - M 1 is a first cationic element selected from the group consisting of H, Li, Na, Mg, Al, and Ga, preferably Li; - M 2 is a second cationic element selected from the group consisting of La, Ba, Sr, Ca, In, Mg, Y, Sc, Cr, Al, K, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; - M 3 is a third cationic element selected from the group consisting of Zr, Ta, Nb, Sb, Sn, Hf, Bi, W, Si, Se, Ga, and Ge; - a, b, c, and d are positive numbers including various combinations of integers and decimals) has the general formula of.

[0065] In a preferred embodiment, the garnet-type inorganic particles are Li x La y Zr z A w O 12 (wherein, - A represents one or more dopants selected from the group consisting of Al, Ga, Nb, Fe, Nd, Pt, Ta, W, Mo, Hf, Si, Ca, Sr, Ba, Ge, and mixtures thereof, preferably selected from the group consisting of Al, Ga, Nb, Fe, Nd, Pt, Ta, W, and mixtures thereof, more preferably selected from the group consisting of Al, Ga, W, and mixtures thereof, ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​ In another embodiment, oxide-based solid ion-conducting inorganic particles are phosphate-based inorganic particles such as lithium aluminum germanium phosphate (LAGP), lithium titanium phosphate (LTP), lithium aluminum titanium phosphate (LATP), lithium oxynitride phosphate (also known as LiPON), lithium nitride (Li3N), lithium halides, and lithium hydrate.

[0070] The electrodes of an electrochemical cell are called anodes or cathodes. The anode is defined as the electrode where electrons leave the cell and oxidation occurs, while the cathode is defined as the electrode where electrons enter the cell and reduction occurs. Each electrode can be either an anode or a cathode depending on the direction of the current flowing through the cell. A bipolar electrode is an electrode that functions as the anode of one cell and as the cathode of another cell. When the cell is charged, the anode is the positive electrode and the cathode is the negative electrode, while when the cell is discharged, the anode is the negative electrode and the cathode is the positive electrode.

[0071] In this invention, the term "positive electrode" is intended to mean, in particular, the electrode of an electrochemical cell in which reduction occurs during discharge, while the term "negative electrode" is intended to mean, in particular, the electrode of an electrochemical cell in which oxidation occurs during discharge.

[0072] In the present invention, the term "processing aid" is intended to refer to a substance that can be used in the manufacture of an electrode or separator to facilitate the formation of a mixture of components and / or the formation of a thin film of the electrode or separator, such as a non-aqueous solvent or a lubricant.

[0073] In the present invention, the processing aid may be further present in the electrode-forming composition.

[0074] The non-aqueous solvent is not particularly limited, as long as it is compatible with the electroactive substance and / or solid ion-conducting inorganic material of the resulting electrode-forming composition.

[0075] In one embodiment, the non-aqueous solvent is selected from the group consisting of nitrile-containing solvents, ethers, esters, thiols, thioethers, ketones, and tertiary amines.

[0076] In one preferred embodiment, the non-aqueous solvent is a nitrile-containing solvent having the general formula R-CN (wherein R represents an alkyl group). Non-limiting examples of nitrile-containing solvents include acetonitrile, butyronitrile, valeronitrile, isobutylnitrile, and the like.

[0077] In another preferred embodiment, the non-aqueous solvent is an ether having the general formula R1-O-R2 (wherein R1 and R2 independently represent alkyl groups). Ether-based solvents include cyclic ethers based on 3, 5, or 6-membered rings. Cyclic ethers can be substituted with alkyl groups, can be unsaturated, and can have additional functional elements such as nitrogen or oxygen atoms in the ring. Non-limiting examples of (cyclic) ether-based solvents include diethyl ether, 1,2-dimethoxy ether, cyclopentyl methyl ether, diethyl ether, dibutyl ether, 1,3-dioxolane, anisole, tetrahydrofuran, methyltetrahydrofuran, tetrahydropyran, and the like.

[0078] In another preferred embodiment, the non-aqueous solvent is an ester having the general formula R3-C(O)O-R4 (wherein R3 and R4 independently represent alkyl groups). Non-limiting examples of ester solvents include butyl butyrate, heptyl butyrate, isobutyl isobutyrate, and ethyl benzoate.

[0079] In another preferred embodiment, the non-aqueous solvent is a thiol having the general formula R5=SH or a thioether having the general formula R6-S-R7 (wherein R5, R6, and R7 are independently alkyl groups). Thioether solvents include cyclic thioethers based on 3, 5, or 6-membered rings. Cyclic thioethers can be substituted with alkyl groups, can be unsaturated, and can have additional functional elements such as nitrogen or oxygen atoms in the ring. Non-limiting examples of thiol solvents include ethanethiols, tert-dodecyl mercaptans, thiophenols, tert-butyl mercaptans, octanuthiols, dimethyl sulfide, ethyl methyl sulfide, methyl benzyl sulfide, etc.

[0080] In another preferred embodiment, the non-aqueous solvent is a ketone having the general formula R8R9C=O (wherein R8 and R9 independently represent alkyl groups). Non-limiting examples of ketone solvents include methyl ethyl ketone, methyl isobutyl ketone, di-isobutyl ketone, acetophenone, benzophenone, and preferably methyl isobutyl ketone.

[0081] In another preferred embodiment, the non-aqueous solvent is R 10 R 11 R 12 N (wherein, R 10 , R 11 and R 12 A tertiary amine has the general formula (where is independently an alkyl group). The N atom of a tertiary amine may be embedded in a 3, 5, or 6-membered ring. Non-limiting examples of tertiary amine solvents include triethylamine, dimethylbutylamine, tributylamine, cyclohexyldimethylamine, and N-ethylpiperidine.

[0082] In the present invention, R1 to R 12The alkyl groups are defined as linear alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl; cyclic alkyl groups (or "cycloalkyl," "alicyclic," or "carbocyclic" groups) such as cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl; branched alkyl groups such as isopropyl, tert-butyl, sec-butyl, and isobutyl; alkyl-substituted alkyl groups such as alkyl-substituted cycloalkyl groups; and "alkyl groups" containing saturated hydrocarbons having one or more carbon atoms, including cycloalkyl-substituted alkyl groups as defined above. Furthermore, alkyl groups may contain one or more functional groups such as unsaturated, ether, carbonyl, carboxyl, hydroxyl, thio, thiol, thiooxy, sulfo, nitrile, nitro, nitroso, azo, amide, imide, amino, imino, or halogen.

[0083] In preferred embodiments, the non-aqueous solvent includes nitrile-containing solvents such as acetonitrile; ethers such as tetrahydrofuran, 2-methyl-tetrahydrofuran, 2,5-dimethyl-tetrahydrofuran, 1,3-dioxolane, diethyl ether, and 1,2-dimethoxy ether; esters such as butyl butyrate; and ketones such as methyl isobutyl ketone.

[0084] In a more preferred embodiment, the non-aqueous solvent is an ester such as butyl butyrate.

[0085] In another, more preferred embodiment, the non-aqueous solvent is a ketone such as methyl isobutyl ketone.

[0086] Non-exclusive examples of lubricants include aliphatic hydrocarbons, particularly isoparaffinic hydrocarbon compounds and petroleum fractions, more specifically squalene. Preferred petroleum fractions include gasoline (C4-C4). 10 ), naphtha (C4~C 11 ), and petroleum / paraffin (C 10 ~C 16 ), as well as mixtures thereof.

[0087] In preferred embodiments, the lubricant is selected from the group consisting of isoparaffinic hydrocarbon compounds and petroleum fractions.

[0088] In certain embodiments, the lubricant is squalene.

[0089] In one embodiment, the amount of lubricant is 1.0 to 35.0 parts by weight (pbw), preferably 3.0 to 30.0 pbw, and more preferably 5.0 to 25.0 pbw, relative to the total weight of the electrode forming composition containing the binder composition of the present invention, at least one electroactive substance, at least one solid ionic conductive inorganic material, and at least one processing aid such as a lubricant.

[0090] One or more conductive agents may be added to the electrode-forming composition to improve the conductivity of the electrodes obtained by manufacturing according to the method of the present invention. Conductive agents for secondary batteries are known in the art. Non-limiting examples include carbonaceous materials, such as carbon black, graphite powder, carbon nanotubes (single-layer or multi-layer), vapor-grown carbon fibers (VGCF), graphene, or fibers, or fine powders or fibers of metals such as nickel or aluminum. An optional conductive agent is preferably carbon black. Carbon black is available, for example, under the brand names Super P® or Ketjenblack®.

[0091] The amount of optional conductive agent is preferably 0 to 20% by weight of the total solids in the electrode-forming composition. For example, in the case of a positive electrode-forming composition, the optional conductive agent is typically 0% to 10% by weight, more preferably 0% to 5% by weight, of the total solids in the composition. In a particular embodiment, the amount of conductive agent is 0.1% to 10% by weight, preferably 0.5% to 8% by weight, more preferably 1% to 5% by weight, of the total solids in the electrode-forming composition.

[0092] A second object of the present invention is a separator-forming composition comprising the binder composition according to the present invention, at least one solid ion-conducting inorganic material, and optionally at least one processing aid.

[0093] In the present invention, the term "separator" is intended to mean, as herein, a single-layer or multi-layer film that electrically and physically separates electrodes of opposite polarity within an electrochemical device and is permeable to ions flowing between them.

[0094] A third object of the present invention is a method for manufacturing an electrode or separator, - A step of fibrillating a TFE(co)polymer by processing the electrode-forming composition or separator-forming composition according to the present invention; - Next, a process of calendering or extruding the composition into a film; and - A step of optionally laminating the film onto a current collector or substrate to manufacture an electrode or separator; This method includes [something].

[0095] In one embodiment, the film is laminated directly onto the surface of the electrode to manufacture a separator.

[0096] In certain embodiments, an additional grinding step is performed before the calendering or extrusion step for forming the film.

[0097] Treatment with high shear forces induces at least partial fibrillation of the TFE(co)polymer, generating fibrils that ultimately form a matrix or lattice to support the resulting composition. The resulting aggregates or fabric may be calendered multiple times to produce a film of the desired thickness and density.

[0098] In certain embodiments, the TFE(co)polymer according to the present invention has two transition temperatures of approximately 19°C and approximately 30°C. Below approximately 19°C, the TFE(co)polymer particles slide easily against each other while maintaining their identity. However, above the transition temperature of approximately 19°C, the structure of the TFE(co)polymer particles becomes looser and more susceptible to mechanical shear. Therefore, shearing causes the crystalline structure of the TFE(co)polymer to unravel, forming a so-called fibrillation phenomenon, i.e., a three-dimensional (3D) structure consisting of nodes, fibrils connecting the nodes, and free space between the fibrils and nodes. Fibrillation occurs when particles rub against a surface, drawing fibrils from the surface of the TFE(co)polymer particles. At temperatures above 30°C, a more advanced fibrillation continues.

[0099] In a more specific embodiment, the fibrillation step of the TFE(co)polymer is carried out at a temperature ranging from 20°C to the melting temperature of the TFE(co)polymer.

[0100] In another, more specific embodiment, the fibrillation process includes two substeps: i) homogenizing the composition into a powder at a temperature of 19°C or lower, and ii) blending the powder into an aggregated powder or paste at a temperature of 30°C or higher.

[0101] In a preferred embodiment, i) the homogenization substep is carried out at a temperature of approximately 10°C to approximately 19°C.

[0102] In another preferred embodiment, ii) the blending substep is carried out at a temperature from about 20°C to the melting temperature of the TFE(co)polymer.

[0103] In a more preferred embodiment, the step of fibrillating the TFE(co)polymer is carried out at a temperature of 20°C to 320°C, preferably 30°C to 300°C, and more preferably 40°C to 250°C.

[0104] In the present invention, the apparatus that can be used for fibrillation is not particularly limited, as long as it can apply sufficient shear force and temperature. Non-limiting examples of such apparatus include high-shear mixers, such as kneaders, internal mixers, and high-shear impact mixers; grinding devices, such as ball mills or jet air mills; and extruders, such as twin-screw extruders, two-roll mills, or four-roll mills.

[0105] In another specific embodiment, the calendering or extrusion process is carried out at a temperature of 320°C or lower, preferably 300°C or lower, and more preferably 250°C or lower.

[0106] In another, more specific embodiment, the calendering or extrusion process is carried out at a temperature of 30°C to 150°C, preferably 35°C to 120°C, and more preferably 40°C to 100°C.

[0107] The calendering process can be appropriately carried out using a calender equipped with rolls having a slight speed difference to generate shear force in the calender gap. Such shear force can also be provided by passing the electrode-forming composition or separator-forming composition through an extruder.

[0108] The electrode-forming composition and the separator-forming composition can be subjected to multiple mechanical compressions, gradually reducing the gap and applying progressive shear force to the film. To produce a film of the desired thickness and density, the roll rotation speed and gap can be changed in each subsequent pass through the calender.

[0109] The mechanical compression process may be related to the thermal consolidation process. The combination of pressurization and heat treatment allows for thermal consolidation at lower temperatures than if it were performed alone.

[0110] In one embodiment, a film obtained from a calendering or extrusion process is laminated onto a current collector or substrate to manufacture an electrode or separator.

[0111] In the present invention, the type of "current collector" depends on whether the electrode provided by it is a positive or negative electrode. When the electrode of the present invention is a positive electrode, the current collector typically contains, and is preferably composed of, at least one metal selected from the group consisting of aluminum (Al), nickel (Ni), titanium (Ti), and their alloys, preferably Al. When the electrode of the present invention is a negative electrode, the current collector typically contains, and is preferably composed of, at least one metal selected from the group consisting of lithium (Li), sodium (Na), zinc (Zn), magnesium (Mg), copper (Cu), and their alloys, preferably Cu.

[0112] A fourth object of the present invention is an electrode or separator obtained by the method of the present invention, wherein the TFE(co)polymer has a 3D structure comprising nodes, fibrils connecting the nodes to each other, and free space between the fibrils and the nodes.

[0113] In one embodiment, the fluorine-containing surfactant is detected in an amount of 100 parts per billion (ppb) or less, preferably 20 ppb or less, and more preferably 2 ppb or less, relative to the total mass of the electrode or separator.

[0114] In another embodiment, the fluorine-containing surfactant is detected in an amount of 5 parts per million (ppm) or less, preferably 1 ppm or less, and more preferably 100 ppm or less, relative to the total mass of the binder composition containing the TFE(co)polymer.

[0115] In the present invention, the term "fluorine-containing surfactant" is intended to refer to surfactants containing fluorocarbon chains that are effective in reducing the surface tension of water, such as perfluorosulfonic acids like perfluorooctanesulfonic acid (PFOS), and perfluorocarboxylic acids like perfluorooctanoic acid (PFOA).

[0116] In certain embodiments, the fluorine-containing surfactant is perfluoroC3-C3. 10Alkanes, preferably perfluoroC4-C8 alkanes, and more preferably perfluoroC4-C6 alkanes.

[0117] In preferred embodiments, the electrode or separator obtained by the method of the present invention is substantially free of fluorine-containing surfactants.

[0118] The term "substantially fluorine-free," when combined with the amount of fluorine-containing surfactant, is intended to exclude the presence of any significant amount of fluorine-containing surfactant.

[0119] A fifth object of the present invention is, - A step of forming a paste by mixing an electrode-forming composition as defined in the present invention with at least one liquid electrolyte, optionally at least one metal salt, and optionally at least one conductive agent; - A process of processing the paste to fibrillate the TFE(co)polymer; - The process of extruding the paste into a film; - A process of obtaining a gel polymer electrode by calendering and / or laminating a film onto a current collector; This is a method for manufacturing gel polymer electrodes containing [a specific substance].

[0120] In one embodiment, the paste extrusion step is carried out at a temperature of less than 120°C, preferably less than 110°C, and more preferably less than 100°C.

[0121] For the purposes of this invention, the term "liquid electrolyte" is intended to mean a liquid medium containing one or more substances that are in a liquid state at atmospheric pressure and 20°C.

[0122] The selection of liquid electrolytes is not particularly limited, provided that they are suitable for solubilizing the metal salt to obtain the electrolyte.

[0123] In one embodiment, the liquid electrolyte comprises at least one organic carbonate.

[0124] In certain embodiments, the liquid electrolyte is an organic carbonate which may be partially or completely fluorinated. In the present invention, the organic carbonate may be cyclic or acyclic. Non-limiting examples of organic carbonates include, in particular, ethylene carbonate (1,3-dioxolan-2-one), propylene carbonate, 4-methylene-1,3-dioxolan-2-one, 4,5-dimethylene-1,3-dioxolan-2-one, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dipropyl carbonate, methyl propyl carbonate, methyl butyl carbonate, ethyl butyl carbonate, propyl butyl carbonate, and dibutyl Examples include carbonates, di-tert-butyl carbonate, butylene carbonate, mono- and difluorinated propylene carbonates, mono- and difluorinated butylene carbonates, 3,3,3-trifluoropropylene carbonate, fluorinated dimethyl carbonate, fluorinated diethyl carbonate, fluorinated ethyl methyl carbonate, fluorinated dipropyl carbonate, fluorinated dibutyl carbonate, fluorinated methyl propyl carbonate, and fluorinated ethyl propyl carbonate.

[0125] In another embodiment, the liquid electrolyte comprises at least one ionic liquid and optionally at least one organic carbonate.

[0126] For the purposes of this invention, the term "ionic liquid" is intended to mean a compound formed by a combination of positively charged cations and negatively charged anions in a liquid state at temperatures below 100°C under atmospheric pressure.

[0127] Ionic liquids are typically, - One or more C1-C 30 A positively charged cation selected from the group consisting of imidazolium, pyridinium, pyrrolidinium, and piperidinium ions that optionally contain an alkyl group, - A negatively charged anion selected from the group consisting of halides, perfluoroanions, and borates. Includes.

[0128] C1~C 30 Non-limiting examples of alkyl groups include, in particular, methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, pentyl, isopentyl, 2,2-dimethylpropyl, hexyl, 2,3-dimethyl-2-butyl, heptyl, 2,2-dimethyl-3-pentyl, 2-methyl-2-hexyl, octyl, 4-methyl-3-heptyl, nonyl, decyl, undecyl, and dodecyl groups.

[0129] The positively charged cations in the ionic liquid are preferably, - Formula: [ka] (In the formula, R is equal to or different from each other) 11 and R 22 R independently represents a C1-C8 alkyl group, which may be equal to or different from each other. 33 , R 44 , R 55 and R 66 These are independently hydrogen atoms or C1~C 30 Alkyl alkyl groups, preferably C1-C 18 (Alkyl alkyl group, more specifically, C1-C8 alkyl groups) The pyrrolidinium cation, and - Formula: [ka] (In the formula, R is equal to or different from each other) 11 and R 22 R independently represents a C1-C8 alkyl group, which may be equal to or different from each other. 33 , R 44 , R 55 , R 66 and R 77 These are independently hydrogen atoms or C1~C 30 Alkyl alkyl groups, preferably C1-C 18 (Alkyl alkyl group, more specifically, C1-C8 alkyl groups) The piperidinium cation, It is selected from the group consisting of the following.

[0130] The positively charged cations in the ionic liquid are more preferably, - Formula: [ka] The pyrrolidinium cation, and - Formula: [ka] The piperidinium cation, It is selected from the group consisting of the following.

[0131] The negatively charged anions in the ionic liquid are preferably, - Equation (SO2CF3)2N - bis(trifluoromethylsulfonyl)imide, - Formula PF6 - Hexafluorophosphate, - Model BF4 - Tetrafluoroborate, and -formula: [ka] Oxaloborat, It is selected from the group consisting of the following.

[0132] The ionic liquid is more preferably a pyrrolidinium cation as defined above and (SO2CF3)2N - PF6 - , and BF4 - It includes a perfluoroanion selected from the group consisting of the following.

[0133] Metal salts are typically, (a) MeI, Me(PF6) where Me is a metal, preferably a transition metal, alkali metal or alkaline earth metal, more preferably Me is Li, Na, K or Cs, even more preferably Me is Li, n is the valence of the metal, typically n is 1 or 2. n Me (BF4) n Me(ClO4) n Me (bis(oxalato)borate) n ("Me(BOB) n ”), MeCF3SO3, Me[N(CF3SO2)2] n , Me[N(C2F5SO2)2] n , Me[N(CF3SO2)(R F SO2)] n (In the formula, R F (These are C2F5, C4F9, or CF3OCF2CF2), Me(AsF6) n , Me[C(CF3SO2)3] n Me2S n ; (b) [ka] (In the formula, R' F These are F, CF3, CHF2, CH2F, C2HF4, C2H2F3, C2H3F2, C2F5, C3F7, C3H2F5, C3H4F3, C4F9, C4H2F7, C4H4F5, C5F 11 , selected from the group consisting of C3F5OCF3, C2F4OCF3, C2H2F2OCF3 and CF2OCF3); and (c) combinations of those It is selected from the group consisting of the following.

[0134] In a preferred embodiment, Me is Li.

[0135] Non-limiting examples of lithium salts according to the present invention include, in particular, lithium ion complexes, such as lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium hexafluoroantimonate (LiSbF6), lithium hexafluorotantalate (LiTaF6), lithium tetrachloroaluminate (LiAlCl4), lithium tetrafluoroborate (LiBF4), and lithium chloroborate (Li2B). 10 Cl 10 ), lithium fluoroborate (Li2B 10 F 10 ), Li2B 12 F x H 12-x (x=0~12), LiPF x (R F ) 6-x and LiBF y (R F ) 4-y (R F is perfluoro C1~C 20 (Representing an alkyl group or perfluoroaromatic group, where x=0~5 and y=0~3), lithium bis(oxalato)borate [LiB(C2O4)2], lithium bis(malonato)borate [LiB(O2CCH2CO2)2], lithium bis(difluoromalonato)borate [LiB(O2CCF2CO2)2], lithium difluorooxalatoborate, and lithium fluoromalonato(difluoro)borate, LiPF2 [O2C(CX2)] n CO2]2, LiPF4[O2C(CX2)] n CO2] (X is selected from the group consisting of H, F, Cl, C1-C4 alkyl groups and fluorinated alkyl groups, and n=0-4), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(fluorosulfonyl)imide Li(FSO2)2N(LiFSI), LiN(SO2C m F 2m+1 )(SO2C n F 2n+1 ) and LiC(SO2C k F 2k+1 )(SO2C m F 2m+1 )(SO2Cn F 2n+1 )(k=1~10, m=1~10, n=1~10), LiN(SO2C p F 2p SO2) and LiC (SO2C p F 2p SO2)(SO2C q F 2q+1 Examples include (where p=1 to 10 and q=1 to 10), or combinations thereof.

[0136] In a preferred embodiment, the lithium salt is lithium bis(trifluoromethanesulfonyl)imide (LiN(CF3SO2)2)(LiTFSI).

[0137] In another preferred embodiment, the lithium salt is LiFSI.

[0138] In another preferred embodiment, the lithium salt is LiPF6.

[0139] A sixth object of the present invention is a gel polymer electrode obtained by the method according to the present invention.

[0140] In one embodiment, the fluorine-containing surfactant is detected in an amount of 100 ppb or less, preferably 20 ppb or less, and more preferably 2 ppb or less, relative to the total mass of the gel polymer electrode or gel polymer separator.

[0141] In another embodiment, the fluorine-containing surfactant is detected in an amount of 5 ppm or less, preferably 1 ppm or less, and more preferably 100 ppb or less, relative to the total mass of the binder composition.

[0142] In preferred embodiments, the gel polymer electrode obtained by the method of the present invention is substantially free of fluorine-containing surfactants.

[0143] A seventh object of the present invention is a secondary battery comprising an electrode and / or separator according to the present invention.

[0144] The present invention also relates to a secondary battery containing a gel polymer electrode according to the present invention.

[0145] Another object of the present invention is 4m measured according to the ISO9277 method 2 / g or less, preferably 2m 2 This involves the use of TFE(co)polymers having a specific surface area of ​​less than / g in binder compositions for secondary batteries.

[0146] If any disclosure of a patent, patent application, or publication incorporated herein by reference conflicts with the description of this application to such an extent that it obscures certain terms, the description herein shall prevail.

[0147] The present invention will be described in more detail below in relation to the following embodiments, but the purpose is merely illustrative and not intended to limit the scope of the invention. [Examples]

[0148] raw materials - Algoflon(registered trademark) F5:2.5m 2 Suspension-polymerized PTFE with a specific surface area of ​​ / g, commercially available from Solvay Specialty Polymers Italy. - Algoflon(registered trademark) DF120: 6.8m 2 Emulsified polymerized PTFE with a specific surface area of ​​ / g, commercially available from Solvay Specialty Polymers Italy. - LPSCl (Li6PS5Cl), crystalline sulfide-based solid ion-conducting inorganic particles, commercially available from NEI Corporation; - NMC622 (Cellcore (registered trademark) NMC KHX12): Cathode active material, commercially available from Umicore; - C-NERGY TM Super C65: Carbon black used as a conductive agent, commercially available from Imerys.

[0149] Fabrication of positive electrodes (E1 and CE1) The positive electrodes (E1 and CE1) were fabricated using a two-step process.

[0150] In the first step, NMC622 and C65 were mixed in a high-shear mixer at low speed for 30 seconds and then at medium speed for 3 minutes. Next, Algoflon® F5 or Algoflon® DF120 were added to the mixture, and the mixture was mixed in the same mixer at high speed for 2 minutes, followed by another 30 seconds at high speed. The mass ratio of the electrode-forming composition was 95:2:3 (NMC622:C65:Algoflon® F5 or Algoflon® DF120). In the final stage, the temperature inside the mixer rose from approximately 26°C to approximately 33°C.

[0151] The second step was a hot rolling process in a two-roll calender preheated to 120°C. The calender rolls were set to have a slight speed difference in a ratio of 1.2:1.0 to generate shear force within the calender gap. The main roll was driven at a rotational speed of 2 rpm, and the second roll was driven at a speed of 2.4 rpm. Next, the powder obtained in the first step was introduced into the narrowed calender gap to produce a slightly sticky film that adhered to the rolls. The film was then peeled off the rolls and subsequently passed through the calender five times. During this process, the gap was gradually narrowed from 2000 μm to 250 μm by applying a gradually increasing shear force to the film, avoiding an excessive increase in compressive force. In each step, the gap was approximately 75% of the previous step. After the calender gap reached approximately 250 μm, the film was folded into quarters, rotated 90°, and then re-inserted into the calender for processing following the same procedure. In this process, the gap was narrowed to 250 μm by starting at 1000 μm and passing the material through the gap approximately 6 to 7 times.

[0152] As a result, a self-supporting film with a thickness of approximately 250 μm was obtained. The thickness of the fabricated cathode was further reduced by using another calendering apparatus with two rolls that rotate at the same speed but with a gap between the rolls reduced to 50 μm. As a result, a cathode with a thickness of approximately 90 μm was obtained. This entire process was carried out without the use of solvents.

[0153] Subsequently, the positive electrode was simultaneously laminated onto a 20 μm thick Al sheet at a temperature of 180°C and a pressure of 25 bar.

[0154] Fabrication of a cathode using sulfide-based solid ion-conducting inorganic particles (E2) The cathode was prepared in the same manner as in E1, except that sulfide-based solid ion-conducting inorganic particles (LPSCl) were added after the mixture of NCM622 and C65. The resulting mixture was then mixed at a moderate speed for 3 minutes. Finally, Algoflon® F5 was added, and the mixture was blended at a low speed for 30 seconds, and then at a very high speed, i.e., a tip speed of 15 m / s, for 3 minutes.

[0155] The mass ratio in the electrode-forming composition was 75:20:2:3 (NMC622:LPSCl:C65:Algoflon(registered trademark)F5).

[0156] Finally, the cathode-forming composition prepared in the previous mixing step was calendered in a GK300L calender with a friction ratio of 1.5:1 while heating to 120°C. The powder was calendered with an initial gap of 70 μm and a power of approximately 300 N / mm, and this was repeated twice to produce a film. The film was then peeled from the roll to obtain a self-supporting film. This film can be used to produce a cathode by directly calendering it on a carbon-coated Al current collector.

[0157] Measurement of mechanical properties To demonstrate that the mechanical properties of a cathode fabricated using Algoflon® F5 (E1) are equivalent to those of a cathode fabricated using Algoflon® DF120 (CE1), the longitudinal (MD) tensile strength (TS) was measured according to the ASTM D88-00 method. The MD TS value for E1 was recorded as 0.87 MPa, and the MD TS value for CE1 was recorded as 0.79 MPa.

[0158] The MD TS value for E2 was also measured and recorded as 0.34 MPa.

[0159] The inventors have demonstrated that cathodes exhibiting equivalent mechanical properties can be fabricated by using either Algoflon® F5 or Algoflon® DF120. In particular, by using Algoflon® F5, a cathode electrode substantially free of fluorine-containing surfactants was obtained without impairing other properties. This was clearly demonstrated by the fact that the cathode was processed into a self-supporting film. Excellent mechanical properties were also observed in cathodes using sulfide-based solid ion-conducting inorganic particles (E2).

[0160] Fabrication of separators using sulfide-based solid ion-conducting inorganic particles (E3) A separator-forming composition consisting of LPSCl and Algoflon(registered trademark) F5 in a mass ratio of 97:3 (LPSCl:Algoflon(registered trademark) F5) was directly applied to the positive electrode surface with a thickness of approximately 84 μm to produce a film-type separator.

[0161] The procedure was the same as in E2, except that the mixing was performed at ultra-high speed for 5 minutes instead of 3 minutes. The separator-forming composition was processed twice in a calender using the same protocol as in E2, except that the friction ratio was 2:1 instead of 1.5:1. Finally, the separator was simultaneously laminated onto the positive electrode (corresponding to E2 above, applied directly to the current collector) to form a layered structure, i.e., a structure containing the separator, positive electrode, and current collector in that order.

Claims

1. - A binder composition containing tetrafluoroethylene (TFE) (co)polymer, - At least one electroactive substance, - At least one solid ion-conducting inorganic material, optionally selected from, - At least one processing aid is optionally selected, An electrode-forming composition comprising, The TFE(co)polymer is measured according to ISO 9277 method, 4m ２ / g or less, preferably 2m ２ A composition having a specific surface area of ​​less than or equal to / g.

2. The composition according to claim 1, wherein the TFE(co)polymer is a TFE homopolymer, a TFE copolymer, or a blend thereof.

3. The composition according to claim 2, wherein the TFE copolymer contains additional repeating units derived from at least one comonomer different from TFE in an amount of 5 mol% or less, preferably 1 mol% or less, relative to the total number of moles of repeating units of the TFE copolymer.

4. The binder composition further comprises a vinylidene difluoride (VDF)-based (co)polymer, wherein the VDF-based (co)polymer comprises at least 50 mol%, preferably at least 60 mol%, of VDF-derived repeating units relative to the total repeating units of the VDF-based (co)polymer, and optionally at least one comonomer different from VDF, preferably of formula: 【Chemistry 1】 (In the formula, each of R1, R2, and R3 is either equal to or different from one another, and independently represents a hydrogen atom or C) １ ~C ３ It is a hydrocarbon group, R ＯＨ is a C containing a hydroxyl group, or at least one hydroxyl group. １ ~C ５ (It is a hydrocarbon part.) The composition according to any one of claims 1 to 3, comprising repeating units derived from a hydrophilic (meth)acrylic comonomer according to the formula.

5. The aforementioned solid ion-conducting inorganic material is - Li １０ SnP ２ S １２ such as lithium tin phosphorus sulfide ("LSPS") materials; - Equation (Li ２ S) ｘ - (P ２ S ５ ) ｙ (In the equation, x + y = 1 and 0 ≤ x ≤ 1), Li ７ P ３ S １１ Li ７ PS ６ Li ４ P ２ S ６ Li ９．６ P ３ S １２ and Li ３ PS ４ Lithium phosphate ("LPS") materials such as glass, crystalline, or glass-ceramic; - Li ２ CuPS ４ LiLi １＋２ｘ Zn １－ｘ PS ４ (in the formula, 0≦x≦1), Li ３．３３ Mg ０．３３ P ２ S ６ , and Li ４－３ｘ Sc ｘ P ２ S ６ Doped LPS (where 0 ≤ x ≤ 1 in the formula); - Lithium phosphorus sulfide oxygen ("LPSO") material of formula LixPySzO (wherein 0.33 ≤ x ≤ 0.67, 0.07 ≤ y ≤ 0.2, 0.4 ≤ z ≤ 0.55, 0 ≤ w ≤ 0.15); - Li １０ GeP ２ S １２ and Li １０ SiP ２ S １２ Lithium phosphide materials containing X such as Si, Ge, Sn, As, and Al ("LXPS"); - Lithium phosphate oxygen ("LXPSO") containing X, where X is Si, Ge, Sn, As, or Al; - Lithium silicon sulfide ("LSS") materials; - Li ３ BS ３ and Li ２ S-B ２ S ３ - Lithium boron sulfide materials such as LiI; - Li ０．８ Sn ０．８ S ２ Li ４ SnS ４ Li ３．８３３ Sn ０．８３３ As ０．１６６ S ４ Li ３ AsS ４ -Li ４ SnS ４ , Li substitution for Ge ３ AsS ４ Lithium tin sulfide materials and lithium arsenide materials, as well as - General formula Li ａ PS ｂ X ｃ A lithium phosphorus sulfide material of the formula Li (wherein X represents at least one halogen element selected from the group Cl, Br, and I, or a combination thereof; a represents a number from 2.0 to 7.0; b represents a number from 3.5 to 6.0; and c represents a number from 0 to 3.0), preferably of the formula Li ６ PS ５ Algyrodite-type sulfide materials of Y (wherein Y is Cl, Br, or I) (These compounds are, for example, LLi ６－ｘ PS ５－ｘ Cl １＋ｘ (For example, 0 ≤ x ≤ 0.5, there may be a deficiency of sulfur, lithium, or halogen, or the material may be doped with heteroatoms); The composition according to any one of claims 1 to 4, wherein the sulfide-based solid ion-conducting inorganic particles are selected from the group consisting of the following.

6. The composition according to any one of claims 1 to 5, wherein the processing aid is a non-aqueous solvent selected from the group consisting of nitrile-containing solvents, ethers, esters, thiols, thioethers, ketones, and tertiary amines, or a lubricant selected from the group consisting of isoparaffinic hydrocarbon compounds and petroleum fractions.

7. - A binder composition containing tetrafluoroethylene (TFE) (co)polymer, - At least one type of solid ion-conducting inorganic material, - At least one processing aid is optionally selected, A separator-forming composition comprising, The TFE(co)polymer is measured according to ISO 9277 method, 4m ２ / g or less, preferably 2m ２ A separator-forming composition having a specific surface area of ​​less than or equal to / g.

8. The composition according to claim 7, wherein the TFE copolymer contains additional repeating units derived from at least one comonomer different from TFE in an amount of 5 mol% or less, preferably 1 mol% or less, relative to the total number of moles of repeating units of the TFE copolymer.

9. A method for manufacturing an electrode or separator, - A step of fibrillating the TFE(co)polymer by processing the electrode-forming composition according to any one of claims 1 to 6 or the separator-forming composition according to claim 7 or 8; - Next, a step of calendering or extruding the composition into a film; and - A step of optionally laminating the film onto a current collector or substrate to manufacture an electrode or separator; A method that includes this.

10. An electrode or separator obtained by the method of claim 9, wherein the TFE(co)polymer has a three-dimensional (3D) structure comprising nodes, fibrils connecting the nodes to each other, and free space between the fibrils and the nodes.

11. The electrode or separator according to claim 10, wherein the fluorine-containing surfactant is detected in an amount of 100 parts per billion (ppb) or less, preferably 20 ppb or less, and more preferably 2 ppb or less, relative to the total mass of the electrode or separator.

12. A method for manufacturing a gel polymer electrode, - A step of mixing the binder composition according to any one of claims 1 to 4, at least one liquid electrolyte, optionally at least one metal salt, and optionally at least one conductive agent to form a paste; - A step of processing the paste to fibrillate the TFE(co)polymer; - The process of extruding the paste to form a film; - A step of obtaining a gel polymer electrode by calendering and / or laminating the film onto a current collector; A method that includes this.

13. A gel polymer electrode obtained by the method of claim 12, wherein the TFE(co)polymer has a three-dimensional (3D) structure comprising nodes, fibrils connecting the nodes to each other, and free space between the fibrils and the nodes.

14. The gel polymer electrode according to claim 13, wherein the fluorine-containing surfactant is detected in an amount of 100 parts per billion (ppb) or less, preferably 20 ppb or less, and more preferably 2 ppb or less, relative to the total mass of the gel polymer electrode.

15. A secondary battery comprising an electrode and / or separator according to claim 10 or 11, or a gel polymer electrode according to claim 13 or 14.

16. 4m measured according to ISO 9277 method ２ / g or less, preferably 2m ２ Use of tetrafluoroethylene (TFE)(co)polymer having a specific surface area of ​​less than / g in a binder composition for secondary batteries.

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