High-Performance Battery Binder

Abstract

The present invention relates to fluorinated copolymers containing repeating units bearing silane groups and their use as binders for electrodes in Li-ion batteries.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to European Patent Application No. 22211974.5, filed December 7, 2022, the entire contents of which are incorporated herein by reference for all purposes.

[0002] The present invention relates to fluorinated copolymers containing repeating units bearing silane groups and their use as binders for electrodes in Li-ion batteries. [Background technology]

[0003] Fluoropolymers are known in the art to be suitable as binders for the manufacture of electrodes for use in electrochemical devices such as secondary batteries.

[0004] Polyvinylidene fluoride (PVDF) is particularly widely used for this purpose.

[0005] To improve the safety and performance of non-aqueous electrolyte secondary batteries, the binder must have high adhesiveness to the active material and current collector contained in the electrode mixture, but the adhesiveness of PVDF is not sufficient.

[0006] Various methods have been proposed to improve the adhesion of PVDF.

[0007] Vinylidene fluoride (VDF) copolymers containing repeat units derived from hydrophilic (meth)acrylic monomers (e.g., acrylic acid) are well known in the art to have excellent mechanical properties, be chemically inert, and have adequate adhesion to metals.

[0008] JP 2022-029314A discloses an electrode mixture for a positive electrode containing a high-nickel-based positive electrode active material, a vinylidene fluoride copolymer, and a silane coupling agent.

[0009] It is believed that there remains a challenge in the art of batteries, and in particular lithium batteries, to provide alternative electrode binders that are characterized by very good adhesion properties. Summary of the Invention

[0010] The object of the present invention is therefore a binder composition [binder (B)] for use in the preparation of an electrode for an electrochemical device, which comprises in the main chain: - Formula -SiY m wherein m is an integer from 1 to 3, and each occurrence of Y is C1 to C 10 Hydrolyzable groups, preferably C2 to C5 hydrolyzable groups) A repeating unit having at least one silane group [unit (CS)], - optionally repeat units derived from at least one fluorinated monomer [monomer (FM)] different from VDF, - optionally repeat units derived from at least one monomer (FPM) comprising at least one functional group [group (FX)] selected from the group consisting of hydroxyl groups, amines, carboxylic acid groups, thiol groups and anhydrides; The binder composition [binder (B)] is characterized by comprising at least one VDF-based polymer [polymer (F)] comprising:

[0011] In another aspect, the present invention provides an electrode-forming composition [composition (C1)] for use in fabricating an electrode for an electrochemical device, comprising: a) at least one electrode active material (AM); b) at least one binder (B) comprising at least one polymer (F) as defined above; c) at least one organic solvent (OS); The present invention provides an electrode-forming composition [composition (C1)] characterized by comprising:

[0012] In a further aspect, the present invention provides an electrode-forming composition [composition (C2)] for use in fabricating an electrode for an electrochemical device, comprising: a) at least one electrode active material (AM); b) at least one binder (B) comprising at least one polymer (F) as defined above; c) an electrolyte solution [solution (ES)] containing at least one metal salt [metal salt (S)] and a liquid medium [medium (L1)]; The present invention provides an electrode-forming composition [composition (C2)] characterized by comprising:

[0013] In another aspect, the present invention relates to the use of either the electrode-forming composition (C1) or the electrode-forming composition (C2) in a method for producing an electrode (E), said method comprising: (I) providing a metal substrate having at least one surface; (II) providing either the electrode-forming composition (C1) or the electrode-forming composition (C2) defined above; (III) applying either composition (C1) or composition (C2) provided in step (II) onto at least one surface of the metal substrate provided in step (I), thereby providing an assembly comprising a metal substrate coated on at least one surface with composition (C1) or composition (C2); (IV) drying the assembly provided in step (III); (V) Optionally, the dried assembly obtained in step (IV) is subjected to a compression step to obtain the electrode (E) of the invention. Provide for use, including

[0014] In a further aspect, the present invention relates to an electrochemical device, such as a secondary battery or a capacitor, comprising at least one electrode (E) as defined above. DETAILED DESCRIPTION OF THE INVENTION

[0015] The term "fluorinated monomer [monomer (FM)]" is intended herein to refer to an ethylenically unsaturated monomer, different from VDF, containing at least one fluorine atom.

[0016] The term "at least one fluorinated monomer" is understood to mean that the polymer (F) may contain, in addition to VDF, repeat units derived from one or more fluorinated monomers. In the remainder of the text, the expressions "fluorinated monomers" are understood for the purposes of the present invention both in the plural and in the singular, i.e. they are understood to mean both one or more fluorinated monomers as defined above.

[0017] Non-limiting examples of suitable monomers (FM) include, among others: C2-C8 perfluoroolefins, such as tetrafluoroethylene and hexafluoropropylene, - C2 to C8 hydrogen-containing fluoroolefins such as vinyl fluoride, 1,2-difluoroethylene and trifluoroethylene; - Formula CH2=CH-R f0 (In the formula, R f0 is a C1-C6 perfluoroalkyl) perfluoroalkylethylene, chloro- and / or bromo- and / or iodo-C2-C6 fluoroolefins, such as chlorotrifluoroethylene; - Formula CF2=CFOR f1 (In the formula, R f1 is C1-C6 fluoro- or perfluoroalkyl, for example CF3, C2F5, C3F7), (per)fluoroalkyl vinyl ethers, CF2=CFOX0(per)fluoro-oxyalkyl vinyl ether (wherein X0 is C1-C 12 Alkyl groups, C1-C 12 C1-C with one or more ether groups such as oxyalkyl groups or perfluoro-2-propoxy-propyl groups 12 (per)fluorooxyalkyl groups), - Formula CF2=CFOCF2ORf2 (In the formula, R f2 is a C1-C6 fluoro- or perfluoroalkyl group, for example a C1-C6 (per)fluorooxyalkyl group having one or more ether groups, such as CF3, C2F5, C3F7 or -C2F5-O-CF3, (per)fluoroalkyl vinyl ethers, Formula CF2 = CFOY0 (wherein Y0 is C1 to C 12 Alkyl group or (per)fluoroalkyl group, C1-C 12 C1-C having an oxyalkyl group or one or more ether groups 12 and Y0 contains a carboxylic or sulfonic acid group in the form of its acid, acid halide or salt), fluorodioxoles, preferably perfluorodioxoles Examples include:

[0018] Preferred monomers (FM) are selected from the group consisting of tetrafluoroethylene (TFE) and chlorotrifluoroethylene (CTFE).

[0019] Term “Formula-SiY m The term "repeating unit having at least one silane group [unit (CS)]" as used herein refers to a repeating unit having the formula -SiY m wherein m is an integer from 1 to 3, and each occurrence of Y is selected from the group consisting of C1 to C6 10 The hydrolyzable group is preferably a C2 to C5 hydrolyzable group.

[0020] According to a first variant of the invention, the units (CS) are at least of the formula -SiY m where m and Y are as defined above. Preferably, the group Y is an alkoxy group, such as an ethoxy group or a methoxy group, or a C1-C hydroxyl group having at least one hydroxyl group. 10 It is an alkyl group.

[0021] According to a first variant of the invention, the polymer (F) is typically prepared by reacting VDF with at least one compound of formula -SiY according to procedures known in the literature. m wherein m and Y are as defined above), and optionally at least one monomer (FM) and optionally at least one monomer (FPM), can be obtained by polymerizing in suspension in an organic medium or in aqueous emulsion.

[0022] According to a second variant of the invention, the units (CS) are derived from the chemical modification of a repeating unit from at least one monomer (FPM) by reaction of at least one functional group [group (FX)] contained in the monomer (FPM) with a compound bearing at least a silane functional group [compound (M)].

[0023] According to this second variant of the invention, the polymer (F) is typically - (i) polymerizing VDF and, optionally, at least one monomer (FM) and at least one monomer (FPM) comprising at least one functional group (FX) to obtain a polymer (FH) carrying at least one functional group (FX), followed by (ii) substituted at least some of the groups (FX) of the polymer (FH) with at least one of the groups of formula -SiY m with a compound (M) having a silane functional group It can be obtained by a method comprising:

[0024] The monomer (FPM) comprises at least one functional group [group (FX)] selected from the group consisting of hydroxyl, amine, carboxyl, thiol and anhydride.

[0025] The monomers (FPM) may be chosen from (per)fluorinated and hydrogenated monomers comprising at least one functional group [group (FX)], with hydrogenated monomers being preferred.

[0026] Suitable hydrogenated monomers (FPM) are represented by formula (I): [ka] (In the formula, R1, R2 and R3 are equal to or different from each other and are independently selected from a hydrogen atom and a C1-C3 hydrocarbon group; and R X is a C1-C hydroxyl group, an amine, a carboxylic acid group, a thiol group, and an anhydride, containing at least one functional group [group (FX)] 20 hydrocarbon moiety) It is a monomer of

[0027] Rx may contain other functional groups different from the group (FX) and may contain heteroatoms.

[0028] The monomer (FPM) is in particular of formula (II): [ka] (wherein R1, R2 and R3 are as defined above, and R H is a hydrogen atom or at least one functional group [group (FX) selected from the group consisting of a hydroxyl group, an amine, a carboxyl group, a thiol group and an anhydride] H )] including C1 to C 20 hydrocarbon moiety) More preferably, the functional group (FX H ) is selected from the group consisting of a hydroxyl group and a carboxyl group.

[0029] Non-limiting examples of monomers (FPM) include, among others, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxyethylhexyl (meth)acrylate, acrylic acid (AA), and succinic acid 1-[2-(acryloyloxy)propyl] ester.

[0030] When the functional group (FX) in the monomer (FPM) is an amine, it may be suitably selected from primary and secondary amines, and said amines may be both aliphatic and aromatic amines.

[0031] The compound (M) having at least a silane functional group suitably has the formula (III): X 4-m SiY m (III) wherein m is an integer from 1 to 3, each occurrence of Y is a hydrolyzable group, and each occurrence of X is a hydrocarbon group, and at least one X contains at least one epoxy functional group. is a compound of

[0032] The units (CS) according to this second variant are derived from the chemical modification of a repeating unit derived from at least one monomer (FPM) by reaction with a compound having at least a compound (M), in which at least some of the groups (FX) of the repeating unit derived from the monomer (FPM) are reacted with at least some of the compound (M), thereby forming -SiY m A repeat unit is provided that includes at least one monomer having a pendant group.

[0033] The polymer (FH) typically has the formula (I): [ka] (In the formula, R1, R2 and R3 are equal to or different from each other and are independently selected from a hydrogen atom and a C1-C3 hydrocarbon group; and R X is a C1-C hydroxyl group, an amine, a carboxylic acid group, a thiol group, and an anhydride, containing at least one functional group [group (FX)] 20 hydrocarbon moiety) The polymer (FH) contains 0.01 mol % to 10.0 mol % of repeating units derived from at least one monomer [monomer (FPM)] of the above, and the molar percentage is relative to the total number of moles of repeating units in the polymer (FH).

[0034] Rx may contain other functional groups different from the group (FX) and may contain heteroatoms.

[0035] The determination of the average mole percentage of repeating monomer (FRM) units in the polymer (FH) can be carried out by any suitable method, in particular by acid-base titration (e.g., suitable for determining the carboxylic acid content), NMR (suitable for quantifying the monomers (FPM) containing aliphatic hydrogen atoms in the side chain), or weight balance based on all the supplied monomers (FPM) and unreacted residual monomers (FPM) during the preparation of the polymer (FH).

[0036] In a particularly preferred embodiment, the monomers (FPM) are randomly distributed in the polymer (FH), in which a proportion of at least 40% of the monomers (FPM) are randomly distributed in the polymer (FH).

[0037] The expression "randomly distributed in the polymer (FH)" is intended to represent the percentage ratio between the average number (%) of monomer (FPM) sequences contained between two repeat units derived from monomer (FM) and the average total number (%) of monomer (FPM) repeat units according to the following formula:

number

[0038] If each of the (FPM) repeat units is isolated, i.e., contained between two repeat units of VDF or monomer (FM), the average number of (FPM) sequences is equal to the average total number of (FPM) repeat units, and therefore the percentage of randomly distributed units (FPM) is 100%, which corresponds to a completely random distribution of the (FPM) repeat units.

[0039] Thus, as noted above, the greater the number of isolated (FPM) units relative to the total number of (FPM) units, the higher the percentage value of the portion of randomly distributed units (FPM) will be.

[0040] The polymer (FH) can be amorphous or semi-crystalline.

[0041] The term "amorphous" is intended herein to mean a polymer (FH) having a heat of fusion of less than 5 J / g, preferably less than 3 J / g, more preferably less than 2 J / g, measured according to ASTM D-3418-08.

[0042] The term "semi-crystalline" is intended herein to mean a polymer (FH) having a heat of fusion measured according to ASTM D3418-08 of between 10 and 90 J / g, preferably between 30 and 60 J / g, more preferably between 35 and 55 J / g.

[0043] The polymer (FH) is preferably semi-crystalline.

[0044] Preferably, the intrinsic viscosity of the polymer (FH), measured in dimethylformamide at 25° C., is comprised between 0.05 l / g and 0.80 l / g, more preferably between 0.10 l / g and 0.50 l / g, and even more preferably between 0.2 l / g and 0.4 l / g.

[0045] The polymer (FH) preferably comprises units derived from vinylidene fluoride (VDF) and from at least one monomer (FPM) as defined above, and optionally also comprises repeat units derived from at least one additional monomer (FM) different from VDF. The additional monomer (FM) in the polymer (FH) is preferably HFP.

[0046] The polymer (FH) is preferably (a) at least 60 mol %, preferably at least 75 mol %, more preferably at least 85 mol % vinylidene fluoride (VDF); (b) optionally, 0.1 mol % to 15 mol %, preferably 0.5 mol % to 10 mol %, more preferably 1 mol % to 5 mol % of at least one monomer (FM) selected from vinyl fluoride (VF1), chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), tetrafluoroethylene (TFE), trifluoroethylene (TrFE), and perfluoromethyl vinyl ether (PMVE); (c) 0.01 mol % to 10 mol %, preferably 0.05 mol % to 5 mol %, more preferably 0.1 mol % to 2 mol % of at least one monomer of formula (I) (FPM) as defined above; Includes.

[0047] The polymer (FH) is typically obtained by emulsion or suspension polymerization.

[0048] Step (ii) of reacting at least a portion of the polymer (FH) with a compound (M) having at least a silane functional group comprises: - providing a composition [composition (C)] containing a liquid medium [medium (L)] and at least one polymer (FH) as defined above, - contacting the composition (C) with at least the compound (M) defined above to obtain a mixture (Cm) comprising at least the polymer (F) and the medium (L); Includes.

[0049] For the purposes of the present invention, the term "liquid medium [medium (L)]" is intended herein to refer to a composition comprising one or more substances that are in the liquid state at 20°C at atmospheric pressure.

[0050] According to some embodiments of the present invention, the medium (L) is preferably selected from an organic carbonate, an ionic liquid (IL), a solvent (S) or a mixture thereof.

[0051] Within the present invention, solvent (S) is intended to denote a solvent suitable for dissolving the polymer (FH) defined above. For this purpose, the solvent (S) is typically selected from the group consisting of N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphamide, dioxane, tetrahydrofuran, tetramethylurea, triethyl phosphate, trimethyl phosphate, aliphatic ketones, cycloaliphatic ketones and cycloaliphatic esters. These solvents can be used alone or in a mixture of two or more species.

[0052] According to a first embodiment of the invention, said medium (L) comprises at least one organic carbonate as the only medium (L).

[0053] Non-limiting examples of suitable organic carbonates include, among others, ethylene carbonate, propylene carbonate, mixtures of ethylene carbonate and propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl-methyl carbonate, butylene carbonate, vinylene carbonate, fluoroethylene carbonate, fluoropropylene carbonate, and mixtures thereof.

[0054] According to a second embodiment of the invention, said medium (L) comprises at least one ionic liquid (IL) as the only medium (L).

[0055] The term "ionic liquid (IL)" is intended herein to denote compounds formed by the combination of positively charged cations and negatively charged anions that exist in the liquid state at temperatures below 100°C under atmospheric pressure.

[0056] Ionic liquids (ILs) are protic ionic liquids (ILs) p ), aprotic ionic liquids (IL a ) and mixtures thereof.

[0057] "Protic Ionic Liquids (ILs)p The term "cation" as used herein refers to a group in which the cation is one or more H + It is intended to denote ionic liquids that contain hydrogen ions.

[0058] One or more H + Non-limiting examples of cations containing hydrogen ions include imidazolium, pyridinium, pyrrolidinium, or piperidinium rings, among others, where the positively charged nitrogen atom is H + It is bonded to a hydrogen ion.

[0059] Aprotic ionic liquids (ILs) a )" is used herein to mean a group in which the cation is H + It is intended to denote ionic liquids that do not contain hydrogen ions.

[0060] Ionic liquids (ILs) are typically chosen from those comprising a sulfonium ion as cation or an imidazolium, pyridinium, pyrrolidium or piperidium ring, said ring optionally substituted at the nitrogen atom by one or more alkyl groups, in particular having 1 to 8 carbon atoms, and at the carbon atoms by one or more alkyl groups, in particular having 1 to 30 carbon atoms.

[0061] According to another embodiment of the invention, said medium (L) comprises a mixture of at least one organic carbonate as defined above and at least one ionic liquid (IL) as defined above.

[0062] According to a further embodiment of the invention, said medium (L) comprises a mixture of at least one organic solvent as defined above with at least one organic carbonate as defined above and / or at least one ionic liquid (IL) as defined above.

[0063] The medium (L) in the composition (C) may further comprise one or more additives.

[0064] When one or more additives are present in the liquid medium, non-limiting examples of suitable additives include, among others, those that are soluble in the liquid medium.

[0065] In step (ii), the composition (C) comprises at least one compound represented by formula (III): X 4-m SiY m (III) wherein m is an integer from 1 to 3, each occurrence of Y is a hydrolyzable group, and each occurrence of X is a hydrocarbon group, and at least one X contains at least one epoxy functional group. is contacted with compound (M).

[0066] The weight ratio of the amounts of compound (M) and polymer (FH) reacted in step (ii) is advantageously between 0.01 and 0.5, preferably between 0.050 and 0.25.

[0067] The polymer (FH) and the metal compound (M) are typically reacted at a temperature comprised between 20°C and 250°C.

[0068] A person skilled in the art will appropriately select the temperature depending on the boiling point of the medium (L) and the equipment and techniques used for the reaction in the process.

[0069] In step (ii), composition (C) advantageously further comprises at least one catalyst.

[0070] The catalyst for the grafting reaction between the polymer (FH) and the metal compound (M) is preferably selected from the group consisting of organoaluminum compounds such as aluminum trifluoromethanesulfonate.

[0071] Usually, the molar amount of compound (M) added in step (ii) corresponds at least to the molar amount of monomer (FPM) present in composition (C).

[0072] When the molar amount of compound (M) added in step (ii) is less than the molar amount of monomer (FPM) present in composition (C), polymer (F) comprises repeating units derived from monomer (FPM) having unreacted functional groups (FX) selected from the group consisting of hydroxyl groups, amines, carboxyl groups, thiol groups and anhydrides.

[0073] The weight ratio between the amounts of medium (L) and polymer (FH) in composition (C) is advantageously between 0.1 and 10, preferably between 1 and 4.

[0074] In step (ii) of the process of the present invention, the catalyst is typically added to composition (C) in an amount comprised between 0.1 mol % and 50 mol %, preferably between 0.3 mol % and 10 mol %, more preferably between 0.5 mol % and 5 mol %, based on the total molar amount of compound (M).

[0075] In step (ii), at least some of the groups (FX) of the monomers (FPM) of the polymer (FH) are reacted with at least some of the compounds (M), thereby forming -SiY m A composition is provided that includes at least one polymer (F) having pendant groups.

[0076] The polymer (F) for use in the binder (B) of the invention is preferably obtained according to the second variant defined above.

[0077] The process for preparing polymer (F) may be suitably carried out in a sealed apparatus such as a reactor or a semi-sealed apparatus such as a twin-screw kneader or an internal mixer, and the reaction in step (ii) is carried out at an elevated temperature in the range of 90 to 120°C.

[0078] The residence time in the equipment depends on the equipment used and the reactivity of the system. A person skilled in the art will select an appropriate time to complete the reaction.

[0079] The reaction time must be adjusted to suit the structure and rotation speed of the apparatus. The residence time in the semi-closed chamber is typically less than 10 minutes, preferably less than 5 minutes.

[0080] The process for preparing the polymer (F) is suitably carried out in a semi-closed apparatus when the medium (L) in the composition (C) is selected from organic carbonates, ionic liquids (IL).

[0081] If the process for preparing polymer (F) is carried out in a closed apparatus, polymer (F) can be isolated as a solid from composition (Cm) obtained after step (ii), which can then be optionally dried and recovered.

[0082] The polymer (F) obtained as defined above can be further ground and isolated as a powder.

[0083] If the process for preparing polymer (F) is carried out in a semi-closed apparatus, the resulting polymer (F) can be pelletized after recovery.

[0084] Either in a closed reactor or in a semi-closed apparatus, the polymer (F) obtained as defined above may then be washed with a polar solvent which may typically be chosen from ketones.

[0085] The polymer (F) can then be filtered, washed, and then dried, typically at a temperature of from 25°C to 100°C.

[0086] Drying can be carried out at atmospheric pressure or under vacuum, or alternatively, in a modified atmosphere, such as an inert gas, typically specifically devoid of moisture (water vapor content less than 0.001% v / v).

[0087] The resulting polymer (F) as defined above is substantially free of residual liquid medium (L).

[0088] Alternatively, the mixture (Cm) obtained at the end of step (ii) can be used for the preparation of an electrode without further washing and / or drying steps.

[0089] In another aspect, the present invention provides an electrode-forming composition [composition (C1)] for use in fabricating an electrode for an electrochemical device, comprising: a) at least one electrode active material (AM); b) at least one binder (B) comprising at least one polymer (F) as defined above; c) at least one organic solvent (OS); The present invention provides an electrode-forming composition [composition (C1)] characterized by comprising:

[0090] The organic solvent (OS) may preferably be a polar solvent, examples of which include N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphamide, dioxane, tetrahydrofuran, tetramethylurea, triethyl phosphate, and trimethyl phosphate. Since the vinylidene fluoride polymer used in the present invention has a degree of polymerization significantly higher than that of conventional polymers, it is more preferable to use a nitrogen-containing organic solvent with greater dissolving power, such as N-methyl-2-pyrrolidone, N,N-dimethylformamide, or N,N-dimethylacetamide, among the above organic solvents. These organic solvents may be used alone or in a mixture of two or more species.

[0091] In a preferred embodiment of the present invention, the electrode-forming composition (C1) is prepared by first dissolving the binder (B) in the solvent (OS) to prepare a binder solution (solution (BS)), and then adding the active material (AM).

[0092] To obtain the binder solution (BS) described above in detail, it is preferred to dissolve 0.1 to 10 parts by weight, particularly 1 to 5 parts by weight, of the copolymer (F) in 100 parts by weight of such an organic solvent (OS).

[0093] To prepare the binder solution (BS), the polymer (F) is preferably dissolved in the organic solvent (OS) at a temperature of 30 to 200°C, more preferably 40 to 60°C, and even more preferably 50 to 150°C.

[0094] For the purposes of the present invention, the term "electrode active material" is intended to mean a compound that is capable of incorporating or intercalating into its structure and subsequently releasing alkali or alkaline earth metal ions therefrom during the charging and discharging stages of an electrochemical cell. The electrode active material is preferably capable of incorporating or intercalating and releasing lithium or sodium ions.

[0095] The nature of the electrode active material in the electrode-forming composition (C1) varies depending on whether the composition is used to manufacture a negative electrode (anode) or a positive electrode (cathode).

[0096] Conventional active materials in the positive electrodes of sodium-ion batteries are generally selected from Na-based layered transition metal oxides, Prussian blue analogues, and polyanion-type materials.

[0097] In some embodiments, the active materials are Na-based layered transition metal oxides classified as O3-, P2-, and P3-type depending on the stacking order of the oxygen layers. P2-type structures generally correspond to the general formula NaxMO2, where M represents a transition metal ion such as Co, Mn, and x is 2 / 3.

[0098] In some embodiments, the active material is Na 0.81 Fe[Fe(CN)6] 0.79 , NaFe2(CN)6, Na1 .1.63 Fe 1.89 (CN)6, Na 1.72 MnFe(CN)6, Na 1.76 Ni 0.12 Mn 0.88 [Fe(CN)6] 0.98 , Na2Ni x Co 1-xFe(CN)6 (0≦x≦1, e.g., Na2CoFe(CN)6), x P[R(CN)6] 1-y . mHO, where A is an alkali metal ion, P is an N-coordinated transition metal ion, R is a C-coordinated transition metal ion, and y is an [R(CN)6] vacancy, with 0≦x≦2 and 0≦y<1.

[0099] In some other embodiments, the active material comprises a series of tetrahedral anionic units (XO4) n- and their derivatives (X m O 3m+1 ) n- having the general formula Na x M y (XO4) n (wherein X=S, P, Si, As, Mo, and W, and M is a transition metal). Among these, phosphates such as NaMPO4, NaFePO4, Na 0.7 FePO4 or NaMnPO4; general formula Na x Sodium superionic conductors with NASICON-type structure of M2(XO4)3 (where 1≦x≦4, M=V, Fe, Ni, Mn, Ti, Cr, Zr; X=P, S, Si, Se, Mo), such as single transition metal types such as Na3V2(PO4)3 (NVP), Na3Cr2(PO4)3, Na3Fe2(PO4)3; binary transition metal types such as Na2VTi(PO4)3, Na3FeV(PO4)3, Na4MnV(PO4)3, Na3MnZr(PO4)3, Na3MnTi(PO4)3, Na4Fe3(PO4)2(P2O7)(NFPP); pyrophosphates such as Na2FeP2O7, Na2MnP2O7, Na2CoP2O7, Na 4-x Fe 2+x / 2 (P2O7)2 (wherein 2 / 3≦x≦7 / 8), for example Na 3.12 Fe 2.44 (P2O7)2 or Na 3.32 Fe 2.34(P2O7)2, Na2(VO)P2O7, Na7V3(P2O7)4; fluorophosphates NaVPO4F, Na2CoPO4F, Na2FePO4F, Na2MnPO4F, Na3(VO 1-x PO4)2F 1+2x where 0≦x≦1, such as Na3(VOPO4)2F or Na3V2(PO4)2F3(NVPF); fluorosulfates, such as NaMSO4F (where M=Fe, Co, Ni); mixed phosphates / pyrophosphates of the general formula Na4M3(PO4)2(PO2O7) (where M represents a transition metal), such as Na4Mn3(PO4)2(PO2O7), Na4Co3(PO4)2(PO2O7), Na4Ni3(PO4)2(PO7), Na4Fe3(PO4)2(PO2O7)(NFPP), Na7V4(PO2O7)4(PO4); sulfates, such as Na2Fe2(SO4)3, Na 2+2x Fe 2-x (SO4)3, Na 2+2x Co 2-x (SO4)3, Na 2+2x Mn 2-x (SO4)3, where 0≦x≦1; silicates of the general formula Na2MSiO4, where M=Mn, Fe, Co, and Ni.

[0100] In some preferred embodiments, the active material is preferably NaVPOF, NaCoPOF, NaFePOF, NaMnPOF, Na(VO 1-x PO4)2F 1+2x where 0≦x≦1, for example a fluorophosphate selected from the list consisting of Na3(VOPO4)2F or Na3V2(PO4)2F3(NVPF).

[0101] Conventional active materials in the positive electrode of a lithium-ion battery may include a composite metal chalcogenide of the formula LiMQ2 (where M is at least one metal selected from transition metals such as Co, Ni, Fe, Mn, Cr, and V, and Q is a chalcogen such as O or S). Among these, it is preferable to use a lithium-based composite metal oxide of the formula LiMO2 (where M is the same as defined above). Preferred examples of these include LiCoO2, LiNiO2, LiNi x Co 1-x O2 (where 0 < x < 1) and spinel-structured LiMn2O4 can be mentioned.

[0102] As an alternative, when forming a positive electrode for a lithium-ion secondary battery, further, the electrode active material (AM) has the formula M1M2(JO4) f E 1-f (where M1 is lithium and can be partially substituted by another alkali metal corresponding to less than 20% of the M1 metal, M2 is a transition metal of +2 oxidation level selected from Fe, Mn, Ni, or a mixture thereof, and can be partially substituted by one or more additional metals of +1 to +5 oxidation levels corresponding to less than 35% of the M2 metal including 0, JO4 is any oxyanion, J is any of P, S, V, Si, Nb, Mo, or a combination thereof, E is a fluoride, hydroxide, or chloride anion, and f is usually the mole fraction of the JO4 oxyanion included in 0.75 to 1) and may include a lithiated or partially lithiated transition metal oxyanion-based electroactive material.

[0103] The M1M2(JO4) f E 1-f The electroactive material is preferably phosphate-based and may have a regular or modified olivine structure.

[0104] More preferably, the electrode active material (AM) when forming the positive electrode has the formula Li 3-x M’ y M’’ 2-y(JO4)3, where 0≦x≦3, 0≦y≦2, M′ and M″ are the same or different metals, at least one of which is a transition metal, JO4 is preferably PO4 which may be partially substituted with another oxyanion, and J is any of S, V, Si, Nb, Mo, or a combination thereof. Even more preferably, the electrode active material has the formula Li(Fe x Mn 1-x )PO4 (where 0≦x≦1, and x is preferably 1) (i.e., lithium iron phosphate of formula LiFePO4).

[0105] When forming a negative electrode for a lithium ion secondary battery, the electrode active material (AM) may preferably include one or more carbon-based materials and / or one or more silicon-based materials.

[0106] In some embodiments, the carbon-based material may be selected from graphite, such as natural or artificial graphite, graphene, or carbon black.

[0107] These materials may be used alone or as a mixture of two or more thereof.

[0108] The carbon-based material is preferably graphite.

[0109] The silicon-based compound may be one or more selected from the group consisting of chlorosilanes, alkoxysilanes, aminosilanes, fluoroalkylsilanes, silicon, silicon chloride, silicon carbide, and silicon oxide.

[0110] More specifically, the silicon-based compound may be silicon oxide or silicon carbide.

[0111] When present in the electrode active material, the silicon-based compound is included in an amount ranging from 1 to 60% by weight, preferably from 5 to 30% by weight, based on the total weight of the electroactive compound.

[0112] One or more optional conductivity-imparting additives may be added to improve the conductivity of the resulting electrodes made from the compositions of the present invention. Conductive agents for batteries are known in the art.

[0113] Examples may include carbon-based materials such as carbon black, graphite fine powder, carbon nanotubes, graphene or fibers, or fine powders or fibers of metals such as nickel or aluminum. The optional conductive agent is preferably carbon black. Carbon black is available, for example, under the brand names Super P® or Ketjenblack®.

[0114] If present, the conductive agent is different from the carbon-based material described above.

[0115] The amount of the optional conductive agent is preferably 0 to 30 wt % of the total solids in the electrode-forming composition. In particular, for cathode-forming compositions, the optional conductive agent is typically 0 to 10 wt %, more preferably 0 to 5 wt %, of the total solids in the composition.

[0116] For anode-forming compositions that do not include a silicon-based electroactive compound, the optional conductive agent is typically 0 wt % to 5 wt %, more preferably 0 wt % to 2 wt %, of the total amount of solids in the composition, while for anode-forming compositions that include a silicon-based electroactive compound, it has been found beneficial to incorporate a larger amount of optional conductive agent, typically 0.5 to 30 wt % of the total amount of solids in the composition.

[0117] The electrode-forming composition (C1) can be obtained by adding and dispersing a powdered electrode material (an active material for a battery or an electric double layer capacitor) and, optionally, an additive, such as a conductivity-imparting additive and / or a viscosity modifier, into the binder solution (BS) defined above.

[0118] When the binder solution (BS) is prepared separately and then combined with the electrode active material, optional conductive material, and other additives to prepare composition (C1), an amount of organic solvent (OS) sufficient to form a stable suspension is used. The amount of solvent (OS) used can range from the minimum amount required to form a stable suspension to the amount required to achieve the desired total solids content in the electrode mixture after the electrode active material, optional conductive material, and other solid additives have been added.

[0119] The total solids content (TSC) of the composition (C1) of the present invention is typically comprised between 15 and 70% by weight, preferably between 40 and 60% by weight, relative to the total weight of the composition (C1). The total solids content of the composition (C1) is understood to be the sum of all its nonvolatile components, including in particular the polymer (F), the electrode active material and any solid nonvolatile additional additives.

[0120] In a further aspect, the present invention provides an electrode-forming composition [composition (C2)] for use in fabricating an electrode for an electrochemical device, comprising: a) at least one electrode active material (AM); b) at least one binder (B) comprising at least one polymer (F) as defined above; c) an electrolyte solution [solution (ES)] containing at least one metal salt [metal salt (S)] and a liquid medium [medium (L1)]; The present invention provides an electrode-forming composition [composition (C2)] characterized by comprising:

[0121] In composition (C2), the electrode active material (AM) and binder (B) are as defined above for composition (C1).

[0122] The term "medium (L1)" is intended here to mean any liquid that is electrochemically stable and capable of dissolving the electrolyte salt.

[0123] The medium (L1) is suitably selected from organic carbonates, ionic liquids (IL), sulfones or mixtures thereof, the organic carbonates and ionic liquids (IL) being as defined above.

[0124] Non-limiting examples of suitable sulfones include those of the formula: [ka] (Wherein R1 and R2 are independently free hydrogen, C1 to C 20 R1 and R2 together are either a C3 to C6 alkyl group or a straight chain C1 to C6 alkyl group. 20 Cycloalkyl group or C6-C 30 an aryl group) It is of the type.

[0125] More preferably, the sulfone is sulfolane (tetramethylene sulfone).

[0126] The metal salt (S) is typically (a)MeI, Me(PF6) 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)(RFSO2)] n (wherein RF is C2F5, C4F9 or CF3OCF2CF2), Me(AsF6) n , Me[C(CF3SO2)3] n , Me2S n wherein Me is a metal, preferably a transition metal, alkali metal or alkaline earth metal, more preferably Me is Li, Na, K, Mg, Al or Cs, even more preferably Me is Li, and n is the valence of the metal, typically n is 1 or 2; (b) (Wherein R'F represents F, CF3, CHF2, CH2F, C2HF4, C2H2F3, C2H3F2, C2F5, C3F7, C3H2F5, C3H4F3, C4F9, C4H2F7, C4H4F5, C5F 11 , C3F5OCF3, C2F4OCF3, C2H2F2OCF3 and CF2OCF3), and (c) a combination of them is selected from the group consisting of:

[0127] Said metal salt (S) is advantageously dissolved by said medium (L1).

[0128] In this regard, the concentration of said metal salt (S) in the medium (L1) is advantageously at least 0.01M, preferably at least 0.025M and more preferably at least 0.05M.

[0129] The concentration of metal salt (S) in medium (L1) is advantageously at most 5M, preferably at most 3M, more preferably at most 2M, even more preferably at most 1M.

[0130] In a preferred embodiment of the present invention, the electrode-forming composition (C1) and the composition (C2) contain at least one acid.

[0131] The acid is preferably an organic acid, more preferably selected from formic acid or citric acid.

[0132] Applicants have surprisingly found that when an amount of at least one organic acid salt is present in the electrode-forming composition of the present invention, the adhesion of the composition to a metal substrate is improved.

[0133] In another aspect, the present invention relates to the use of either the electrode-forming composition (C1) or the composition (C2) in a method for producing an electrode (E), said method comprising: (I) providing a metal substrate having at least one surface; (II) providing either the electrode-forming composition (C1) or the composition (C2) defined above; (III) applying either composition (C1) or composition (C2) provided in step (II) onto at least one surface of the metal substrate provided in step (I), thereby providing an assembly comprising a metal substrate coated on at least one surface with composition (C1) or composition (C2); (IV) drying the assembly provided in step (III); (V) Optionally, the dried assembly obtained in step (IV) is subjected to a compression step to obtain the electrode (E) of the invention. Regarding use, including

[0134] Drying step (IV) may also serve to remove any residual liquid medium (L) that may remain entrapped in the formed polymer (F), resulting in an electrode with even improved adhesion to the current collector.

[0135] In a further object, the present invention relates to an electrode (E) obtainable by the method of the present invention.

[0136] In a further aspect, the present invention provides a method for producing an electrode for an electrochemical cell [electrode (E1)], comprising the steps of: A) providing a partially fluorinated fluoropolymer [polymer (F)] as defined above; - B) dry-mixing, without solvent, at least one electrode active material (AM), a polymer (F) as defined above and optionally at least one conductive agent to obtain a dry electrode-forming composition [composition (C3)]; - C) feeding the composition (C) obtained in step B) into a press to form a dry, self-supporting film; D) applying the dry film to a conductive substrate to form an electrode; The present invention provides a method comprising:

[0137] The applicant has surprisingly found that the electrodes (E) and (E1) of the present invention exhibit outstanding adhesion of the binder to the current collector.

[0138] Therefore, the electrode (E) and electrode (E1) of the present invention are particularly suitable for use in electrochemical devices, especially secondary batteries.

[0139] For the purposes of the present invention, the term "secondary battery" is intended to mean a rechargeable battery.

[0140] The secondary battery of the present invention is preferably an alkali metal secondary battery or an alkaline earth metal secondary battery.

[0141] The secondary battery of the present invention is more preferably a lithium ion secondary battery.

[0142] In yet another object, the present invention relates to an electrochemical device comprising at least one electrode (E) and electrode (E1) of the present invention.

[0143] Preferably, the electrochemical device according to the present invention is a secondary battery. - Positive and negative electrodes At least one of the positive electrode and the negative electrode is the electrode (E) and the electrode (E1) of the present invention.

[0144] In one preferred embodiment of the present invention, the electrochemical device comprises: - Positive and negative electrodes wherein the negative electrode is the electrode (E) and the electrode (E1) according to the present invention.

[0145] Electrochemical devices according to the present invention can be fabricated by standard methods known to those skilled in the art.

[0146] To the extent that the disclosure of any patents, patent applications, and publications incorporated herein by reference conflicts with the statements of this application to the extent that a term may be unclear, the statements of this application shall control.

[0147] The invention will now be described in more detail with reference to the following examples, the purpose of which is merely illustrative and not intended to limit the scope of the invention. [Example]

[0148] raw materials Polymer (F-H1): VDF-AA (0.9 mol%)-HFP (2.4 mol%) polymer with a viscosity of 0.30 l / g in DMF at 25°C.

[0149] Epoxysilane (EPP-1): [3-(2,3-epoxypropoxy)propyl]triethoxysilane.

[0150] Catalyst (ATS): Aluminum trifluoromethanesulfonate.

[0151] Medium (EL-1): ethylene carbonate (EC) / propylene carbonate (PC) (weight ratio 1 / 1).

[0152] Determination of the intrinsic viscosity of the polymer (F) The intrinsic viscosity (η) [dl / g] was calculated based on the fall time at 25°C of a solution obtained by dissolving the polymer (F) in N,N-dimethylformamide at a concentration of about 0.2 g / dl using an Ubbelhode viscometer, according to the following formula:

number

[0153] General procedure for preparing polymer (F) in a semi-closed apparatus: A 15 ml twin-screw extruder (DSM Xplore) (Miniextruder) was used. All tests were performed at 100 rpm. The residence time for all tests was 4 minutes.

[0154] Example 1 - Preparation of F-1 with F-H1 by processing in the melt The following ingredients: EL-1 (13.79 g), ATS (7.9 mg), EPP-1 (0.79 g), and polymer (F-H1) (3.94 g) were placed in a Miniextruder at 110 °C. The resulting product was pelletized in a VariCut pelletizer (Thermo Fisher Scientific).

[0155] Example 2 - Preparation of F-2 using F-H1 by processing in the melt The following ingredients: EL-1 (10.64 g), ATS (14.2 mg), EPP-1 (1.42 g), and polymer (F-H1) (7.09 g) were placed in a Miniextruder at 110 °C. The resulting product was pelletized in a VariCut pelletizer (Thermo Fisher Scientific).

[0156] Example 3 - Preparation of an electrode using NMC622 active material Positive electrodes having a final composition of 96.5 wt. % NMC622 (Umicore, d50: 11.6 μm), 1.5 wt. % of either polymer (F-H1), polymer (F-1), or polymer (F-2), and 2 wt. % of a conductive additive were fabricated as follows.

[0157] Example 3a) Reference composition containing polymer (F-H1) A dispersion was prepared by mixing 24.98 g of an 8 wt % solution of polymer (F-H1) in NMP, 128.5 g of NMC622, 2.7 g of SC-65, and 23.8 g of NMP in a centrifugal mixer for 10 minutes to obtain composition 3a).

[0158] Example 3b) Formulations containing polymer (F-1) A dispersion was prepared by mixing 9.51 g of polymer (F-1) (approximately 2 g of pure polymer) pre-dissolved in 39.3 g of NMP, 128.5 g of NMC622, and 2.7 g of SC-65 in a centrifugal mixer for 10 minutes to obtain composition 3b).

[0159] Example 3c) Formulation containing polymer (F-2) A dispersion was prepared by mixing 5.40 g of polymer (F-2) (approximately 2 g of pure polymer) pre-dissolved in 43.4 g of NMP, 128.5 g of NMC622, and 2.7 g of SC-65 in a centrifugal mixer for 10 minutes to obtain composition 3c).

[0160] For each composition 3a), 3b) or 3c), the final slurry was obtained by further stirring with a high speed disc impeller at 2000 rpm for 70 minutes.

[0161] The resulting composition was cast onto an aluminum foil having a thickness of 15.5 μm using a doctor blade, and the coated layer was dried in a vacuum oven at a temperature of 90° C. for about 50 minutes to obtain a cathode a), b), or c). The dried coating layer had a thickness of about 145 μm and a loading of 30 mg / cm. 2 (+ / -2). A small amount of residual EL-1 remained in the electrode b) obtained with composition 3b).

[0162] Example 4: Adhesion The adhesive peel force between the aluminum foil and the electrode was measured as follows: To evaluate the adhesion of the above-defined dried coating layer to the aluminum foil, a 180° peel test was carried out according to the configuration described in standard ASTM D903 at a speed of 300 mm / min at 20° C. The adhesive force values ​​are shown in Table 1.

[0163] [Table 1]

[0164] These results demonstrate that the polymers of the present invention exhibit adequate adhesion to current collectors, comparable to or superior to that of polymer (F-H1) alone, and that adhesion to metals is further improved, especially when the liquid medium used in the preparation of the polymer is completely removed.

Claims

1. A binder composition [binder (B)] for use in the preparation of an electrode for an electrochemical device, comprising in the main chain: - formula - SiY ｍ wherein m is an integer from 1 to 3, and each occurrence of Y is C １ ~C １０ Hydrolyzable groups, preferably C ２ ~C ５ (It is a hydrolyzable group) A repeating unit having at least one silane group [unit (CS)], - optionally repeat units derived from at least one fluorinated monomer [monomer (FM)] different from VDF, - optionally repeat units derived from at least one monomer (FPM) comprising at least one functional group [group (FX)] selected from the group consisting of hydroxyl groups, amines, carboxylic acid groups, thiol groups and anhydrides; 1. A binder composition [binder (B)] characterized by comprising at least one VDF-based polymer [polymer (F)] comprising:

2. 2. The binder (B) according to claim 1, wherein the monomer (FM) is selected from the group consisting of tetrafluoroethylene (TFE) and chlorotrifluoroethylene (CTFE).

3. The units (CS) are at least of the formula -SiY ｍ wherein m is an integer from 1 to 3, and each occurrence of Y is C １ ~C １０ Hydrolyzable groups, preferably C ２ ~C ５ 3. The binder (B) according to claim 1 or 2, which is derived from at least one ethylenically unsaturated functional monomer having a silane functional group, the silane functional group being a hydrolyzable group.

4. The units (CS) are derived from chemical modification of the repeating units derived from at least one monomer (FPM) comprising at least one functional group [group (FX)] selected from the group consisting of hydroxyl groups, amines, carboxylic acid groups, thiol groups and anhydrides, wherein at least a portion of the groups (FX) of the repeating units derived from the monomer (FPM) are represented by formula (III): X ４－ｍ SiY ｍ (III) wherein m is an integer from 1 to 3, each occurrence of Y is a hydrolyzable group, and each occurrence of X is a hydrocarbon group, and at least one X contains at least one epoxy functional group. is reacted with at least a portion of the compound (M) of -SiY ｍ 3. The binder (B) according to claim 1 or 2, which provides repeating units comprising at least one monomer having a pendant group.

5. The monomer (FPM) has the formula (I): 【Chemistry 1】 (In the formula, R １ , R ２ and R ３ are equal to or different from each other, and are a hydrogen atom and C １ ~C ３ are independently selected from hydrocarbon groups, and R Ｘ is a C containing at least one functional group [group (FX)] selected from the group consisting of hydroxyl groups, amines, carboxylic acid groups, thiol groups and anhydrides; １ ~C ２０ hydrocarbon moiety) The binder (B) according to claim 4, which is a hydrogenated monomer (FPM) of the formula:

6. The hydrogenated monomer (FPM) has the formula (II): 【Chemistry 2】 (In the formula, R １ , R ２ and R ３ is as defined above, and RH is a hydrogen atom or at least one functional group selected from the group consisting of a hydroxyl group, an amine, a carboxyl group, a thiol group, and an anhydride [group (FX Ｈ ) )] １ ~C ２０ hydrocarbon moiety) The binder (B) according to claim 5, wherein the (meth)acrylic monomer is selected from the group consisting of:

7. The binder (B) according to any one of claims 4 to 6, wherein the monomer (FPM) is selected from the group consisting of hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxyethylhexyl (meth)acrylate, acrylic acid (AA), and succinic acid 1-[2-(acryloyloxy)propyl] ester.

8. A method for preparing the polymer (F) according to any one of claims 4 to 7, comprising the steps of: (i) polymerizing VDF and optionally at least one monomer (FM) and at least one monomer (FPM) comprising at least one functional group (FX) to obtain a polymer (F-H), followed by (ii) modifying at least some of the groups (FX) of the monomers (FPM) of the polymer (FH) with groups of formula (III): X ４－ｍ SiY ｍ (III) wherein m is an integer from 1 to 3, each occurrence of Y is a hydrolyzable group, and each occurrence of X is a hydrocarbon group, and at least one X contains at least one epoxy functional group. with a compound (M) of A method comprising:

9. Step (ii) is providing a composition [composition (C)] containing a liquid medium [medium (L)] and at least one polymer (F-H) as defined above, - contacting the composition (C) with at least a compound (M) to obtain a mixture (Cm); The method of claim 8, comprising:

10. 10. The method according to claim 8 or 9, wherein the medium (L) is selected from organic carbonates, ionic liquids (IL), solvents (S) or mixtures thereof.

11. An electrode-forming composition [composition (C1)] for use in producing an electrode for an electrochemical device, comprising: a) at least one electrode active material (AM); b) at least one binder (B) according to any one of claims 1 to 7; and c) at least one organic solvent (OS); An electrode-forming composition [composition (C1)] characterized by comprising:

12. Use of the electrode-forming composition (C1) according to claim 11 in a method for producing an electrode (E), said method comprising: (I) providing a metal substrate having at least one surface; (II) Providing the electrode-forming composition (C1) according to claim 12; (III) applying the composition (C1) provided in step (II) onto at least one surface of the metal substrate provided in step (I), thereby providing an assembly comprising a metal substrate coated with the composition (C1) on at least one surface; (IV) drying the assembly provided in step (III); (V) Optionally, the dried assembly obtained in step (IV) is subjected to a compression step to obtain the electrode (E) of the present invention. Including, use.

13. Electrochemical device, such as a secondary battery or a capacitor, comprising at least one electrode (E) obtainable by the method according to claim 12.

14. An electrochemical device comprising the polymer electrolyte membrane of claim 13.

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