Tetrafluoroethylene polymer composition, binder for electrochemical device, electrode mixture, electrode, and secondary battery

Abstract

To provide a tetrafluoroethylene polymer composition for a binder for an electrochemical device that can suppress gas generation inside an electrochemical device cell and degradation of electrochemical device properties and also improve strength of a mixture sheet, as well as a binder for an electrochemical device, an electrode mixture, an electrode, and a secondary battery using the same.SOLUTION: A tetrafluoroethylene polymer composition used as a binder for an electrochemical device contains a tetrafluoroethylene polymer and a polymer compound with ionic groups and is substantially free of water.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a tetrafluoroethylene-based polymer composition, a binder for electrochemical devices, an electrode mixture, an electrode, and a secondary battery. [Background technology]

[0002] Secondary batteries such as lithium-ion secondary batteries are used in small, portable electric and electronic devices such as notebook computers, mobile phones, smartphones, tablet computers, and ultrabooks, due to their high voltage, high energy density, low self-discharge, low memory effect, and the ability to be made extremely lightweight, and are also being put into practical use as a wide range of power sources, including on-board power sources for driving automobiles and large stationary power sources. There is a demand for secondary batteries to have even higher energy density, and further improvements in their battery characteristics are required.

[0003] Patent Document 1 describes an energy storage device in which at least one of the cathode and the anode contains a polytetrafluoroethylene composite binder material.

[0004] Patent Documents 2 to 6 describe the use of polytetrafluoroethylene as a binder for batteries. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2017-517862 [Patent Document 2] International Publication No. 2021 / 181887 [Patent Document 3] International Publication No. 2021 / 181888 [Patent Document 4] International Publication No. 2021 / 192541 [Patent Document 5] International Publication No. 2022 / 138942 [Patent Document 6] International Publication No. 2022 / 138939 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present disclosure is to provide a tetrafluoroethylene polymer composition for a binder for an electrochemical device, which can suppress gas generation inside an electrochemical device cell and deterioration of the electrochemical device characteristics, and can also improve the strength of a composite sheet, as well as a binder for an electrochemical device, an electrode composite, an electrode, and a secondary battery each using the same. [Means for solving the problem]

[0007] The present disclosure (1) relates to a tetrafluoroethylene-based polymer composition used as a binder for electrochemical devices, the tetrafluoroethylene-based polymer composition comprising a tetrafluoroethylene-based polymer and a polymeric compound having an ionic group, and substantially free of moisture.

[0008] The present disclosure (2) is a tetrafluoroethylene polymer composition according to the present invention (1) which is substantially free of fluorine-containing compounds having a molecular weight of 1,000 or less.

[0009] The present disclosure (3) is the tetrafluoroethylene-based polymer composition according to the present invention (1) or (2), which is used as a binder for a solid secondary battery.

[0010] The present disclosure (4) is a binder for electrochemical devices consisting essentially of a tetrafluoroethylene-based polymer composition, the tetrafluoroethylene-based polymer composition containing a tetrafluoroethylene-based polymer and a polymeric compound having an ionic group, and containing substantially no moisture.

[0011] In the present disclosure (5), the ionic group is -SO3M a , -PO3M a and -COOM a(In the formula, M a is -H, metal atom, -NR 2 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 2 is H or an organic group.

[0012] In the present disclosure (6), the ionic group is -SO3M a and -COOM a (In the formula, M a is —H or an alkali metal atom.

[0013] The present disclosure (7) is the binder for electrochemical devices according to any one of the present inventions (4) to (6), wherein the content of the ionic group is 0.8 meq / g or more with respect to the polymer compound.

[0014] The present disclosure (8) is the binder for electrochemical devices according to any one of the present inventions (4) to (7), wherein the total amount of the tetrafluoroethylene-based polymer and the polymer compound is 99.95 mass% or more relative to the tetrafluoroethylene-based polymer composition.

[0015] The present disclosure (9) is the binder for electrochemical devices according to any one of the present inventions (4) to (8), wherein the content of the polymer compound is 0.08 mass % or more and 1.0 mass % or less with respect to the tetrafluoroethylene-based polymer.

[0016] The present disclosure (10) is the binder for electrochemical devices according to any one of the present inventions (4) to (9), wherein the rate of hydrogen atoms bonded to carbon atoms in the polymer compound substituted with fluorine atoms is 50% or more.

[0017] The present disclosure (11) is the binder for electrochemical devices according to any one of the present inventions (4) to (10), wherein the polymer compound has an ion exchange rate of 53 or less.

[0018] The present disclosure (12) relates to the binder for electrochemical devices according to any one of the present inventions (4) to (11), wherein the polymer compound is a water-soluble polymer compound.

[0019] The present disclosure (13) relates to the binder for electrochemical devices according to any one of the present inventions (4) to (12), wherein the polymer compound is at least one selected from the group consisting of a polymer (I) containing a polymerization unit (I) based on a monomer represented by the following general formula (I), and a compound (II) represented by the following general formula (II): General formula (I): CX 1 X 3 =CX 2 R(-CZ 1 Z 2 -A 0 ) m (I) (In the formula, X 1 and X 3 are each independently F, Cl, H or CF3; A 0 is an anionic group; X 2 is H, F, an alkyl group or a fluorine-containing alkyl group; R is a linking group; Z 1 and Z 2 are each independently H, F, an alkyl group or a fluorine-containing alkyl group; and m is an integer of 1 or more. General formula (II): T X -X A -R FA1 -R FA2 -X A -T X ' (II) (In the formula, R FA1 is -Rf 1 p -R F -O q - and R FA2 is -Rf2 p -R FX -O q - and R F is a divalent fluoropolyether group, R FX is a divalent fluoropolyether group containing an anionic group, Rf 1 and Rf 2 each independently represents a C which may be substituted by one or more fluorine atoms; 1-6 is an alkylene group, Each p is independently 0 or 1; Each q is independently 0 or 1; X A each independently represents a single bond or a divalent to decavalent group, T X and T X Each of the C1 to C6′ groups independently contains one or more of H, O, and Cl, and does not contain the anionic group. 24 (hydro)(fluoro)carbon group, and (ii) a C1-C aryl group containing at least one of the anionic groups. 24 (hydro)(fluoro)carbon groups.

[0020] The present disclosure (14) relates to the polymer compound, which is the polymer (I), and X 1 and X 3 are each independently F or H; A 0 -SO3M a Or -COOM a (In the formula, M a is -H or an alkali metal atom); X 2 is F; R is a fluorinated alkylene group having 1 to 4 carbon atoms and containing an ether bond; Z 1 and Z 2 are each independently F or CF3; and m is 1.

[0021] The present disclosure (15) is the binder for electrochemical devices according to any one of the present inventions (4) to (14), wherein the standard specific gravity of the tetrafluoroethylene polymer composition is 2.280 or less.

[0022] The present disclosure (16) is the binder for electrochemical devices according to any one of the present inventions (4) to (15), wherein the water content in the tetrafluoroethylene polymer composition is 0.050 mass % or less.

[0023] The present disclosure (17) is the binder for electrochemical devices according to any one of the present inventions (4) to (16), wherein the water content in the tetrafluoroethylene polymer composition is 0.010 mass % or less.

[0024] The present disclosure (18) is the binder for electrochemical devices according to any one of the present inventions (4) to (17), wherein the tetrafluoroethylene polymer composition has an extrusion pressure of 10 MPa or more at a reduction ratio of 100.

[0025] The present disclosure (19) is the binder for electrochemical devices according to any one of the present inventions (4) to (18), wherein the tetrafluoroethylene-based polymer composition is stretchable.

[0026] The present disclosure (20) is the binder for electrochemical devices according to any one of the present inventions (4) to (19), wherein the tetrafluoroethylene-based polymer is polytetrafluoroethylene.

[0027] The present disclosure (21) is the binder for electrochemical devices according to any one of the present inventions (4) to (20), wherein the tetrafluoroethylene-based polymer contains a tetrafluoroethylene unit and a modified monomer unit based on a modified monomer copolymerizable with tetrafluoroethylene.

[0028] The present disclosure (22) relates to the binder for electrochemical devices according to the present invention (21), wherein the modified monomer is at least one selected from the group consisting of perfluoro(methyl vinyl ether), hexafluoropropylene, vinylidene fluoride, and chlorotrifluoroethylene.

[0029] The present disclosure (23) is the binder for electrochemical devices according to any one of the present inventions (4) to (22), wherein the average primary particle size of the tetrafluoroethylene polymer composition is 100 to 350 nm.

[0030] The present disclosure (24) is the binder for electrochemical devices according to any one of the present inventions (4) to (23), wherein the tetrafluoroethylene polymer composition is substantially free of a fluorine-containing compound having a molecular weight of 1,000 or less.

[0031] The present disclosure (25) is the binder for electrochemical devices according to any one of the present inventions (4) to (24), wherein the tetrafluoroethylene polymer composition is substantially free of any of the fluorine-containing compounds represented by the following formulas: F(CF2)7COOM, F(CF2)5COOM, H(CF2)6COOM, H(CF2)7COOM, CF3O(CF2)3OCHFCF2COOM, C3F7OCF(CF3)CF2OCF(CF3)COOM, CF3CF2CF2OCF(CF3)COOM, CF3CF2OCF2CF2OCF2COOM, C2F5OCF(CF3)CF2OCF(CF3)COOM, CF3OCF(CF3)CF2OCF(CF3)COOM, CF2ClCF2CF2OCF(CF3)CF2OCF2COOM, CF2ClCF2CF2OCF2CF(CF3)OCF2COOM, CF2ClCF(CF3)OCF(CF3)CF2OCF2COOM, CF2ClCF(CF3)OCF2CF(CF3)OCF2COOM, and [ka] (In each formula, M is H, metal atom, NR 1 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. 1 is H or an organic group.

[0032] The present disclosure (26) is the binder for electrochemical devices according to the present invention (24) or (25), wherein the content of the fluorine-containing compound is less than 25 ppb by mass based on the tetrafluoroethylene-based polymer composition.

[0033] The present disclosure (27) is the binder for electrochemical devices according to any one of the present inventions (4) to (26), which is for use in secondary batteries.

[0034] The present disclosure (28) is a binder for electrochemical devices according to the present invention (27) for use in lithium ion secondary batteries.

[0035] The present disclosure (29) is a binder for electrochemical devices according to the present invention (27) or (28), which is for use in solid secondary batteries.

[0036] The present disclosure (30) is the binder for electrochemical devices according to any one of the present inventions (4) to (26) for use in capacitors.

[0037] The present disclosure (31) is an electrode mixture comprising the tetrafluoroethylene polymer composition according to any one of the present inventions (1) to (3), or the binder for electrochemical device according to any one of the present inventions (4) to (29), and an electrode active material.

[0038] The present disclosure (32) is an electrode comprising the tetrafluoroethylene polymer composition according to any one of the present inventions (1) to (3), or the binder for electrochemical device according to any one of the present inventions (4) to (29), an electrode active material, and a current collector.

[0039] The present disclosure (33) is a secondary battery comprising the electrode according to the present invention (32).

[0040] The present disclosure (34) is a mixture for an electrolyte layer comprising the tetrafluoroethylene-based polymer composition according to the present invention (3) or the binder for a solid secondary battery according to the present invention (29) and a solid electrolyte.

[0041] The present disclosure (35) relates to the mixture for an electrolyte layer according to the present invention (34), wherein the solid electrolyte is a sulfide-based solid electrolyte or an oxide-based solid electrolyte.

[0042] The present disclosure (36) is a solid secondary battery comprising the electrolyte layer mixture according to the present invention (34) or (35). Effect of the Invention

[0043] According to the present disclosure, it is possible to provide a tetrafluoroethylene-based polymer composition for a binder for an electrochemical device, which can suppress gas generation inside an electrochemical device cell and deterioration of the electrochemical device characteristics and can also improve the strength of a composite sheet, as well as a binder for an electrochemical device, an electrode composite, an electrode, and a secondary battery each using the same. [Brief description of the drawings]

[0044] [Figure 1] FIG. 2 is a schematic diagram of a cross section of a pressure cell used for measuring the ionic conductivity of a solid electrolyte mixture sheet in the examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] In the present disclosure, the term "organic group" refers to a group containing one or more carbon atoms or a group formed by removing one hydrogen atom from an organic compound. The organic group is preferably an alkyl group which may have one or more substituents.

[0046] The present disclosure will now be described in detail.

[0047] The present disclosure provides a tetrafluoroethylene (TFE)-based polymer composition used in a binder for an electrochemical device, the TFE-based polymer composition comprising a TFE-based polymer and a polymeric compound having an ionic group, and being substantially free of moisture.

[0048] Since the TFE-based polymer composition of the present disclosure has the above-mentioned configuration, it can improve the strength of the composite sheet. In addition, since it does not substantially contain moisture, when it is used as a binder for an electrochemical device, it can suppress gas generation inside an electrochemical device cell and deterioration of electrochemical device characteristics (for example, decrease in capacity during high-temperature storage). In addition, it is not necessary to use a large amount of a dispersion medium such as water or an organic solvent, and it is possible to select a wide range of electrode active materials and solid electrolytes to be combined, which is advantageous in terms of the production process. In addition, it is possible to reduce the process and cost due to the use of a dispersion medium. Furthermore, since the TFE-based polymer composition of the present disclosure has excellent binding strength with active materials and electrolytes, it is possible to reduce the amount used.

[0049] The TFE-based polymer composition of the present disclosure contains a polymer compound having an ionic group together with a TFE-based polymer. The presence of the ionic group can improve the binding strength. The TFE polymer is not included in the polymer compound.

[0050] The presence or absence of an ionic group is determined by the following method. The polymer compound is extracted with methanol, water is added to the resulting methanol extract, and the mixture is distilled under reduced pressure to obtain an aqueous solution. The presence or absence of ionic groups is determined based on the potential difference of the resulting aqueous solution.

[0051] The ionic group is preferably an anionic group, for example, a sulfate group, -COOM a (carboxylate group), phosphate group, -PO3M a (phosphonate group), -SO3M a (sulfonate group), -C(CF3)2OM a (In each formula, M a is -H, metal atom, -NR 2 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 2 is H or an organic group. Among them, -SO3M a , -PO3M a and -COOM a At least one selected from the group consisting of -SO3M a and -COOM a More preferably, at least one selected from the group consisting of -SO3M a and -COOM a (In the formula, M a is -H or an alkali metal atom.

[0052] The content of the ionic group is preferably 0.80 meq / g or more, more preferably 1.20 meq / g or more, even more preferably 1.75 meq / g or more, even more preferably 2.00 meq / g or more, and particularly preferably 2.50 meq / g or more, relative to the polymer compound. The content may also be 10.0 meq / g or less, 8.00 meq / g or less, or 5.00 meq / g or less. The content of the ionic group can be calculated from the composition of the polymer compound.

[0053] The polymer compound preferably contains fluorine atoms, and the ratio of hydrogen atoms bonded to carbon atoms in the polymer compound that are substituted with fluorine atoms is preferably 50% or more. The "ratio of hydrogen atoms bonded to carbon atoms that are substituted with fluorine atoms" is calculated as the ratio of the number of fluorine atoms to the total number of hydrogen atoms bonded to carbon atoms and halogen atoms (including fluorine atoms) bonded to carbon atoms. The ratio of hydrogen atoms bonded to carbon atoms in the polymer compound that are substituted with fluorine atoms is not particularly limited, but is more preferably 70% or more, even more preferably 80% or more, even more preferably 90% or more, particularly preferably 95% or more, and most preferably 100%.

[0054] The polymeric compound preferably has an ion exchange ratio (IXR) of 53 or less. The IXR is defined as the number of carbon atoms in the polymeric backbone relative to an ionic group. Precursor groups that become ionic upon hydrolysis (e.g., -SO2F) are not considered ionic groups for purposes of determining IXR. The IXR is preferably 0.5 or more, more preferably 1 or more, even more preferably 3 or more, even more preferably 4 or more, and particularly preferably 5 or more. The IXR is preferably 43 or less, more preferably 33 or less, and even more preferably 23 or less. In the polymeric compound, the ionic groups are typically distributed along the polymer backbone. The polymeric compound comprises, with recurring side chains attached to the polymer backbone, the side chains preferably carrying the ionic groups.

[0055] The polymer compound is preferably a water-soluble polymer compound. "Water-soluble" means the property of being easily dissolved or dispersed in an aqueous medium. For example, the particle size of a water-soluble polymer compound cannot be measured by dynamic light scattering (DLS), or the particle size is 5 nm or less. On the other hand, for example, the particle size of a water-insoluble polymer compound can be measured by dynamic light scattering (DLS) to be more than 5 nm.

[0056] Whether the above polymer compound is a water-soluble polymer compound can also be determined by the following method. Water is added to the methanol solution containing the polymer compound, and the mixture is distilled under reduced pressure at 40° C. to obtain an aqueous solution. Approximately 1 g of the resulting aqueous solution is dried in a vacuum dryer at 60°C for 60 minutes, the mass of the heating residue is measured, and the ratio of the mass of the heating residue to the mass of the aqueous solution is expressed as a percentage. If this value is 0.1% by mass or more, it is determined to be a water-soluble polymer.

[0057] The number average molecular weight of the polymer compound is 0.1×10 4 More than 0.15×10 is preferred. 4 More preferably, 0.2×10 4 More preferably, 0.3×10 4 More preferably, 0.5×10 4 More preferably, 1.0×10 4 More preferably, 2.0×10 4 More than 3.0×10 is particularly preferable. 4 More than 75.0×10 is the most preferable. 4 Less than 50.0×10 is preferable. 4 Less than 40.0×10 is more preferable. 4 More preferably, 30.0×10 4 The following is particularly preferred: 20.0×10 4 The following are particularly preferred:

[0058] The weight average molecular weight of the polymer compound is 0.1×10 4 More than 0.2×10 is preferred. 4 More preferably, 0.4×10 4 More preferably, 0.6×10 4 More preferably, 1.0×10 4 More preferably, 2.0×10 4 More than 5.0×10 is particularly preferable. 4 More than 150.0×10 is most preferable. 4 The following is preferable: 100.0×10 4 Less than or equal to 80.0×10 is more preferable.4 Less than 60.0×10 is more preferable. 4 The following is particularly preferred: 40.0×10 4 The following are particularly preferred:

[0059] The number average molecular weight and weight average molecular weight are values ​​calculated by gel permeation chromatography (GPC) using monodisperse polystyrene or monodisperse polyethylene oxide (PEO) and polyethylene glycol (PEG) as standards. When measurement by GPC is not possible, the number average molecular weight of the polymer compound can be determined from the correlation between the number average molecular weight calculated from the number of terminal groups obtained by NMR, FT-IR, etc. and the melt flow rate. The melt flow rate can be measured in accordance with JIS K 7210.

[0060] It is preferable that the above polymer compound is substantially free of fractions having a molecular weight of 1000 or less, more preferably substantially free of fractions having a molecular weight of less than 1500, even more preferably substantially free of fractions having a molecular weight of less than 2000, and particularly preferably substantially free of fractions having a molecular weight of less than 3000. "Substantially free of the fraction" means that the content of the fraction relative to the polymer compound is 3.0% by mass or less, preferably 1.0% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.1% by mass or less, relative to the polymer compound. The content of the above fractions can be measured by gel permeation chromatography (GPC) or liquid chromatography-mass spectrometry (LC-MS).

[0061] The polymer compound is preferably substantially free of fluorine-containing compounds having a molecular weight of not more than 1000. "Substantially free of fluorine-containing compounds" means that the amount of the fluorine-containing compounds is not more than 25 ppb by mass relative to the polymer compound. The amount of the fluorine-containing compound is more preferably less than 25 mass ppb, even more preferably 10 mass ppb or less, even more preferably less than 10 mass ppb, even more preferably 5 mass ppb or less, even more preferably 3 mass ppb or less, even more preferably 1 mass ppb or less, and particularly preferably less than 1 mass ppb. The lower limit is not particularly limited, and may be an amount below the detection limit. The above-mentioned fluorine-containing compound having a molecular weight of 1,000 or less and a method for quantifying it will be described later.

[0062] The polymer compound is preferably at least one selected from the group consisting of a polymer (I) containing a polymerization unit (I) based on a monomer represented by the following general formula (I) and a compound (II) represented by the following general formula (II), and is more preferably a polymer (I). General formula (I): CX 1 X 3 =CX 2 R(-CZ 1 Z 2 -A 0 ) m (I) (In the formula, X 1 and X 3 are each independently F, Cl, H or CF3; A 0 is an anionic group; X 2 is H, F, an alkyl group or a fluorine-containing alkyl group; R is a linking group; Z 1 and Z 2 are each independently H, F, an alkyl group or a fluorine-containing alkyl group; and m is an integer of 1 or more. General formula (II): T X -X A -R FA1 -R FA2 -X A -T X ' (II) (In the formula, R FA1 is -Rf 1 p -R F -Oq - and R FA2 is -Rf 2 p -R FX -O q - and R F is a divalent fluoropolyether group, R FX is a divalent fluoropolyether group containing an anionic group, Rf 1 and Rf 2 each independently represents a C which may be substituted by one or more fluorine atoms; 1-6 is an alkylene group, Each p is independently 0 or 1; Each q is independently 0 or 1; X A each independently represents a single bond or a divalent to decavalent group, T X and T X Each of the C1-C ' groups independently contains one or more of H, O, and Cl, and does not contain the above anionic group. 24 (hydro)(fluoro)carbon groups, and (ii) at least one C1-C group containing the anionic group. 24 (hydro)(fluoro)carbon groups.

[0063] The polymer (I) is a polymer containing a polymerization unit (I) based on the monomer (I). The monomer (I) is represented by the following general formula (I). CX 1 X 3 =CX 2 R(-CZ 1 Z 2 -A 0 ) m (I) (In the formula, X 1 and X 3 are each independently F, Cl, H, or CF; X 2 is H, F, an alkyl group or a fluorine-containing alkyl group; A 0is an anionic group; R is a linking group; Z 1 and Z 2 are each independently H, F, an alkyl group or a fluorine-containing alkyl group; and m is an integer of 1 or more. X 1 and X 3 is preferably F or H. 2 is preferably F, Cl, H or CF3, more preferably F. In addition, Z 1 and Z 2 As the substituent, F or CF3 is preferable.

[0064] In the present disclosure, anionic groups include functional groups that provide anionic groups such as sulfate groups, carboxylate groups, and the like, as well as acid groups such as -COOH, acid salt groups such as -COONH4, etc. Anionic groups include sulfate groups, carboxylate groups, phosphate groups, phosphonate groups, sulfonate groups, or -C(CF3)2OM groups. a (In the formula, M a is -H, metal atom, -NR 2 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 2 is H or an organic group. a Or -COOM a (In the formula, M a is the same as above), and -SO3M b Or -COOM b (In the formula, M b is more preferably --H or an alkali metal atom.

[0065] In the production method of the present disclosure, one or more types of monomers can be used as the monomer (I) represented by general formula (I).

[0066] R is a linking group. In the present disclosure, the "linking group" is a (m+1)-valent linking group, and when m is 1, it is a divalent linking group. The linking group may be a single bond, and preferably contains at least one carbon atom, and the number of carbon atoms may be 2 or more, 4 or more, 8 or more, 10 or more, or 20 or more. There is no upper limit, but it may be, for example, 100 or less, or 50 or less.

[0067] The linking group may be linear or branched, cyclic or acyclic in structure, saturated or unsaturated, substituted or unsubstituted, and may optionally contain one or more heteroatoms selected from the group consisting of sulfur, oxygen, and nitrogen, and may optionally contain one or more functional groups selected from the group consisting of esters, amides, sulfonamides, carbonyls, carbonates, urethanes, ureas, and carbamates. The linking group may not contain carbon atoms, but may be a catenary heteroatom such as oxygen, sulfur, or nitrogen.

[0068] m is an integer of 1 or more, preferably 1 or 2, and more preferably 1. When m is an integer of 2 or more, Z 1 , Z 2 and A 0 may be the same or different. Next, a preferred structure when m is 1 in general formula (I) will be described.

[0069] R is preferably, for example, a catenary heteroatom such as oxygen, sulfur, or nitrogen, or a divalent organic group.

[0070] When R is a divalent organic group, the hydrogen atom bonded to the carbon atom may be replaced with a halogen other than fluorine, such as chlorine, and may or may not contain a double bond. R may be either linear or branched, and may be either cyclic or acyclic. R may also contain a functional group (e.g., ester, ether, ketone (keto group), amine, halide, etc.).

[0071] R may also be a non-fluorinated divalent organic group, or a partially fluorinated or perfluorinated divalent organic group.

[0072] R may be, for example, a hydrocarbon group in which no fluorine atoms are bonded to the carbon atom, a hydrocarbon group in which some of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms, or a hydrocarbon group in which all of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms, and these may contain an oxygen atom, a double bond, or a functional group.

[0073] R is preferably a hydrocarbon group having 1 to 100 carbon atoms which may contain an ether bond or a keto group, and in the hydrocarbon group, some or all of the hydrogen atoms bonded to the carbon atoms may be substituted with fluorine. More preferably, R is a fluorinated alkylene group having 1 to 4 carbon atoms which may contain an ether bond, and even more preferably a fluorinated alkylene group having 1 to 4 carbon atoms which contains an ether bond.

[0074] R is preferably -(CH2) a -, -(CF2) a -, -O-(CF2) a -, -(CF2) a -O-(CF2) b -, -O(CF2) a -O-(CF2) b -, -(CF2) a -[O-(CF2) b ] c -, -O(CF2) a -[O-(CF2) b ] c -,-[(CF2) a -O] b -[(CF2) c -O] d -, -O[(CF2) a -O] b -[(CF2) c -O] d -, -O-[CF2CF(CF3)O] a -(CF2) b-, -[CF2CF(CF3)O] a -, -[CF(CF3)CF2O] a -, -(CF2) a -O-[CF(CF3)CF2O] a -, -(CF2) a -O-[CF(CF3)CF2O] a -(CF2) b -, -[CF2CF(CF3)] a -CO-(CF2) b - and at least one selected from combinations thereof. In the formula, a, b, c, and d are independently at least 1. a, b, c, and d may be independently 2 or more, 3 or more, 4 or more, 10 or more, or 20 or more. The upper limit of a, b, c, and d is, for example, 100.

[0075] R is represented by the general formula (r1): -CF2-O-(CX 6 2) e -{O-CF(CF3)} f -(O) g - (r1) (In the formula, X 6 are each independently H, F or CF3, e is an integer of 0 to 3, f is an integer of 0 to 3, and g is 0 or 1), and a divalent group represented by the general formula (r2): -CF2-O-(CX 7 2) e -(O) g - (r2) (In the formula, X 7 are each independently H, F or CF3, e is an integer of 0 to 3, and g is 0 or 1), and a divalent group represented by the following formula is more preferable.

[0076] Specific examples of suitable R include -CF2-O-, -CF2-O-CF2-, -CF2-O-CH2-, -CF2-O-CH2CF2-, -CF2-O-CF2CF2-, -CF2-O-CF2CH2-, -CF2-O-CF2CF2CH2-, -CF2-O-CF(CF3)-, -CF2-O-CF(CF3)CF2-, -CF2-O-CF(CF3)CF2-O-, -CF2-O-CF(CF3)CF2-O-CF2-, -CF2-O-CF(CF3)CH2-, and the like. Among these, R is preferably a perfluoroalkylene group which may contain an oxygen atom, specifically, -CF2-O-, -CF2-O-CF2-, -CF2-O-CF2CF2-, -CF2-O-CF(CF3)-, -CF2-O-CF(CF3)CF2-, or -CF2-O-CF(CF3)CF2-O-.

[0077] -R-CZ of general formula (I) 1 Z 2 - is represented by the general formula (s1): -CF2-O-(CX 6 2) e -{O-CF(CF3)} f -(O) g -CZ 1 Z 2 - (s1) (In the formula, X 6 are each independently H, F, or CF3, e is an integer of 0 to 3, f is an integer of 0 to 3, g is 0 or 1, and Z 1 and Z 2 are each independently H, F, an alkyl group or a fluorine-containing alkyl group), and in formula (s1), Z 1 and Z 2 More preferably, each is F or CF3, and even more preferably, one is F and the other is CF3.

[0078] In addition, in the general formula (I), -R-CZ 1 Z 2 - is represented by the general formula (s2): -CF2-O-(CX 7 2) e -(O) g -CZ1 Z 2 - (s2) (In the formula, X 7 are each independently H, F or CF3, e is an integer of 0 to 3, g is 0 or 1, and Z 1 and Z 2 are each independently H, F, an alkyl group or a fluorine-containing alkyl group), and in formula (s2), Z 1 and Z 2 More preferably, each is F or CF3, and even more preferably, one is F and the other is CF3.

[0079] -R-CZ of general formula (I) 1 Z 2 - as -CF2-O-CF2-, -CF2-O-CF(CF3)-, -CF2-OC(CF3)2-, -CF2-O-CF2-CF2-, -CF2-O-CF2-CF(CF3)-, -CF2-O-CF2-C(CF3)2-, -CF2-O-CF2CF2-CF2-, -CF2-O-CF2CF2- CF(CF3)-, -CF2-O-CF2CF2-C(CF3)2-, -CF2-O-CF(CF3)-CF2-, -CF2-O-CF(CF3)-CF(CF3)-, -CF2-O-CF(CF3)-C(CF3)2-, -CF2-O-CF(CF3)CF2-CF2-, -CF2-O-CF(CF3)CF 2-CF(CF3)-, -CF2-O-CF(CF3)CF2-C(CF3)2-, -CF2-O-CF(CF3)CF2-O-CF2-, -CF2-O-CF(CF3)CF2-O-CF(CF3)-, or -CF2-O-CF(CF3)CF2-OC(CF3)2- is preferred, and -CF2-O-CF( CF3)-, -CF2-O-CF2-CF(CF3)-, -CF2-O-CF2CF2-CF(CF3)-, -CF2-O-CF(CF3)-CF(CF3)-, -CF2-O-CF(CF3)CF2-CF(CF3)-, or -CF2-O-CF(CF3)CF2-O-CF(CF3)- is more preferable.

[0080] It is also preferred that the polymer (I) is highly fluorinated. For example, the polymer (I) may contain phosphate moieties (e.g., CH2OP(O)(OMa ) 2) and a sulfate group moiety (e.g., CH2OS(O)2OM a Anionic groups such as (A 0 ), it is preferred that 80% or more, 90% or more, 95% or more, or 100% of the C-H bonds in the polymer (I) are substituted with C-F bonds.

[0081] The monomer (I) and the polymer (I) each have an anionic group (A 0 ), it is also preferable that the compound has a C-F bond and has no C-H bond. That is, in the general formula (I), 1 , X 2 , and X 3 are all F, and R is preferably a perfluoroalkylene group having 1 or more carbon atoms, and the perfluoroalkylene group may be either linear or branched, may be either cyclic or noncyclic, and may contain at least one catenary heteroatom. The number of carbon atoms in the perfluoroalkylene group may be 2 to 20, or may be 4 to 18.

[0082] The monomer (I) and the polymer (I) may be partially fluorinated. That is, the monomer (I) and the polymer (I) may have an anionic group (A 0 ), it is also preferred that the alkyl group has at least one hydrogen atom bonded to a carbon atom and at least one fluorine atom bonded to a carbon atom.

[0083] Anionic group (A 0 ) is -SO3M a , -OSO3M a , -COOM a , -SO2NR'CH2COOM a , -CH2OP(O)(OM a )2, [-CH2O]2P(O)(OM a ), -CH2CH2OP(O)(OM a )2, [-CH2CH2O]2P(O)(OM a ), -CH2CH2OSO3M a , -P(O)(OM a )2, -SO2NR'CH2CH2OP(O)(OMa )2, [-SO2NR'CH2CH2O]2P(O)(OM a ), -CH2OSO3M a , -SO2NR'CH2CH2OSO3M a , or -C(CF3)2OM a Among them, -SO3M a , -OSO3M a , -COOM a , -P(O)(OM a )2 or C(CF3)2OM a is preferred, -COOM a , -SO3M a , -OSO3M a or C(CF3)2OM a is more preferred, -SO3M a , -COOM a or P(O)(OM a )2 is more preferred, and -SO3M a or COOM a is particularly preferred, and -COOM a is most preferred.

[0084] M a is H, metal atom, NR 2 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 2 is H or an organic group.

[0085] The metal atom includes alkali metals (Group 1), alkaline earth metals (Group 2), etc., and is preferably Na, K or Li.

[0086] M a is -H, a metal atom or NR 2 4 is preferred, and -H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or NR 2 4 is more preferred, -H, -Na, -K, -Li or NH4 is even more preferred, -H, -Na, -K or NH4 is even more preferred, -H, -Na or NH4 is especially preferred, and -H or NH4 is most preferred.

[0087] In the polymer (I), each polymer unit (I) may have a different anionic group or may have the same anionic group. The monomer represented by the general formula (I) is CF2=CF(OCF2CF2SO3M a ), CF2=CF(O(CF2)3SO3M a ), CF2=CF(O(CF2)4SO3M a ), CF2 = CF(OCF2CF(CF3)SO3M a ), CF2=CF(OCF2CF(CF3)OCF2CF2SO3M a ), CF2=CF(OCF2CF2COOM a ), CF2=CF(O(CF2)3COOM a ), CF2=CF(O(CF2)4COOM a ), CF2=CF(O(CF2)5COOM a ), CF2 = CF(OCF2CF(CF3)COOM a ), CF2=CF(OCF2CF(CF3)O(CF2) n COOM a ) (n is greater than 1).

[0088] The monomer (I) is preferably a monomer (1) represented by general formula (1). The polymer (I) is preferably a polymer (1) containing polymerization units (1) based on a monomer represented by general formula (1). CX2=CY(-CZ2-O-Rf-A) (1) (In the formula, X may be the same or different and is -H or F; Y is -H, -F, an alkyl group or a fluorine-containing alkyl group; Z may be the same or different and is -H, -F, an alkyl group or a fluoroalkyl group; Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and having an ether bond; A is -COOM a , -SO3M a , -OSO3M a or C(CF3)2OM a (M a is -H, metal atom, -NR 24. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 2 is H or an organic group. However, at least one of X, Y, and Z contains a fluorine atom.

[0089] In the production method of the present disclosure, the monomer (1) represented by general formula (1) may be copolymerized with other monomers. The polymer (1) may be a homopolymer of the monomer (1) represented by the general formula (1) or a copolymer with other monomers.

[0090] The above-mentioned fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond is an alkylene group that does not contain a structure in which an oxygen atom is at the terminal and contains an ether bond between carbon atoms.

[0091] In general formula (1), X is -H or F. Both X's may be -F, or at least one X may be -H. For example, one X may be -F and the other -H, or both X's may be -H.

[0092] In the general formula (1), Y is -H, -F, an alkyl group or a fluorine-containing alkyl group. The alkyl group is an alkyl group that does not contain a fluorine atom, and may have one or more carbon atoms. The alkyl group preferably has six or less carbon atoms, more preferably four or less, and even more preferably three or less. The fluorine-containing alkyl group is an alkyl group that contains at least one fluorine atom, and may have one or more carbon atoms. The fluorine-containing alkyl group preferably has six or less carbon atoms, more preferably four or less, and even more preferably three or less. The Y is preferably -H, -F or CF3, and more preferably -F.

[0093] In the general formula (1), Z is the same or different and is -H, -F, an alkyl group or a fluoroalkyl group. The alkyl group is an alkyl group that does not contain a fluorine atom, and may have one or more carbon atoms. The alkyl group preferably has six or less carbon atoms, more preferably four or less, and even more preferably three or less. The fluorine-containing alkyl group is an alkyl group that contains at least one fluorine atom, and may have one or more carbon atoms. The fluorine-containing alkyl group preferably has six or less carbon atoms, more preferably four or less, and even more preferably three or less. The Z is preferably -H, -F or CF3, and more preferably -F.

[0094] In the general formula (1), at least one of X, Y, and Z contains a fluorine atom. For example, X may be -H, and Y and Z may be -F.

[0095] In the general formula (1), the above Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond.

[0096] The number of carbon atoms in the fluorine-containing alkylene group is preferably 2 or more. The number of carbon atoms in the fluorine-containing alkylene group is preferably 30 or less, more preferably 20 or less, even more preferably 10 or less, particularly preferably 6 or less, and most preferably 3 or less. Examples of the fluorine-containing alkylene group include -CF2-, -CH2CF2-, -CF2CF2-, -CF2CH2-, -CF2CF2CF2-, -CF2CF2CH2-, -CF(CF3)-, -CF(CF3)CF2-, -CF(CF3)CH2-, and the like. The fluorine-containing alkylene group is preferably a perfluoroalkylene group.

[0097] The number of carbon atoms in the fluorine-containing alkylene group having an ether bond is preferably 3 or more. The number of carbon atoms in the fluorine-containing alkylene group having an ether bond is preferably 60 or less, more preferably 30 or less, even more preferably 12 or less, particularly preferably 9 or less, and most preferably 6 or less. The fluorine-containing alkylene group having an ether bond is, for example, a group represented by the general formula: [ka] (In the formula, Z 1 is F or CF3;Z 2 and Z 3 are H or F;Z respectively 4 is H, F, or CF3; p1+q1+r1 is an integer of 1 to 10; s1 is 0 or 1; and t1 is an integer of 0 to 5).

[0098] Specific examples of the fluorine-containing alkylene group having an ether bond include -CF2CF(CF3)OCF2CF2-, -CF(CF3)CF2-O-CF(CF3)-, -(CF(CF3)CF2-O) n -CF(CF3)- (wherein n is an integer of 1 to 10), -CF(CF3)CF2-O-CF(CF3)CH2-, -(CF(CF3)CF2-O) n Examples include -CF(CF3)CH2- (wherein n is an integer of 1 to 10), -CH2CF2CF2O-CH2CF2CH2-, -CF2CF2CF2O-CF2-, -CF2CF2CF2O-CF2CF2-, -CF2CF2CF2O-CF2CF2CF2-, -CF2CF2CF2O-CF2CF2CH2-, -CF2CF2O-CF2-, -CF2CF2O-CF2CH2-, etc. The fluorine-containing alkylene group having an ether bond is preferably a perfluoroalkylene group.

[0099] In the general formula (1), A is -COOM a , -SO3M a , -OSO3M a or C(CF3)2OM a (M a is H, metal atom, NR 2 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 2 is H or an organic group).

[0100] R 2 As the 1-10 is preferably an organic group represented by the formula: 1-4 More preferred is an organic group represented by the formula:1-4 More preferred are alkyl groups of the formula:

[0101] The metal atom includes alkali metals (Group 1), alkaline earth metals (Group 2), etc., and is preferably Na, K or Li.

[0102] M a is H, a metal atom or NR 2 4 is preferred, H, an alkali metal (group 1), an alkaline earth metal (group 2) or NR 2 4 is more preferred, H, Na, K, Li or NH4 is even more preferred, H, Na, K or NH4 is even more preferred, H, Na or NH4 is especially preferred, and H or NH4 is most preferred.

[0103] A is -COOM a or SO3M a is preferred, -COOM a is more preferred.

[0104] The monomer represented by the general formula (1) may, for example, be a monomer represented by the general formula (1a): CX2 = CFCF2-O-(CF(CF3)CF2O) n5 -CF(CF3)-A (1a) (wherein each X is the same and represents F or H, n5 represents 0 or an integer of 1 to 10, and A is as defined above) is exemplified.

[0105] In general formula (1a), n5 is preferably 0 or an integer from 1 to 5, more preferably 0, 1 or 2, and even more preferably 0 or 1, because particles having a small primary particle size can be obtained.

[0106] In the production method of the present disclosure, the monomer represented by general formula (1a) may be copolymerized with other monomers. The polymer (1) may be a homopolymer of the monomer represented by the general formula (1a) or a copolymer with other monomers.

[0107] The monomer (1) is preferably a monomer represented by the general formula (1A). The polymerized units (1) are preferably polymerized units (1A) based on a monomer represented by general formula (1A). CH2=CF(-CF2-O-Rf-A) (1A) (In the formula, Rf and A are the same as above.)

[0108] In the production method of the present disclosure, the monomer represented by general formula (1A) may be copolymerized with other monomers. The polymer (1) may be a homopolymer of the monomer represented by the general formula (1A) or a copolymer with other monomers.

[0109] Specific examples of the monomer represented by formula (1A) include those represented by the general formula: [ka] (In the formula, Z 1 is F or CF3;Z 2 and Z 3 are H or F;Z respectively 4 is H, F or CF3; p1+q1+r1 is an integer from 0 to 10; s1 is 0 or 1; t1 is an integer from 0 to 5, except that Z 3 and Z 4 are both H, then p1+q1+r1+s1 is not 0; A is as defined above). More specifically, [ka] etc. are preferred, among which [ka] It is preferable that:

[0110] The monomer represented by the general formula (1A) is, for example, a It is preferred that the formula is CH2=CFCF2OCF(CF3)COOM a , and CH2 = CFCF2OCF(CF3)CF2OCF(CF3)COOMa (In the formula, M a is as defined above.) is preferably at least one selected from the group consisting of CH2=CFCF2OCF(CF3)COOM a is more preferred.

[0111] The monomer (I) is also preferably a monomer (2) represented by the general formula (2). The polymer (I) is also preferably a polymer (2) containing polymerized units (2) based on a monomer represented by general formula (2). CX2=CY(-O-Rf-A) (2) (In the formula, X is the same or different and is -H or F; Y is -H, -F, an alkyl group or a fluorine-containing alkyl group; Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having an ether bond or a keto group having 2 to 100 carbon atoms; and A is the same as defined above.)

[0112] The monomer (I) is also preferably a monomer (3) represented by the general formula (3). The polymer (I) is also preferably a polymer (3) containing polymerization units (3) based on a monomer represented by general formula (3). CX2=CY(-Rf-A) (3) (In the formula, X is the same or different and is -H or F; Y is -H, -F, an alkyl group or a fluorine-containing alkyl group; Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having an ether bond having 2 to 100 carbon atoms; and A is the same as defined above.)

[0113] Next, examples of the monomer in the case where m is an integer of 2 or more in the general formula (I) include: [ka] etc.

[0114] The polymer (I) usually has a terminal group. The terminal group is a terminal group generated during polymerization, and representative terminal groups are independently selected from hydrogen, iodine, bromine, linear or branched alkyl groups, and linear or branched fluoroalkyl groups, and may optionally contain at least one catenary heteroatom. The alkyl group or fluoroalkyl group preferably has 1 to 20 carbon atoms. These terminal groups are generally generated from the initiator or chain transfer agent used in the formation of the polymer (I), or are generated during the chain transfer reaction.

[0115] In the polymer (I), the content of the polymerized units (I) is, in order of preference, 1.0 mol% or more, 3.0 mol% or more, 5.0 mol% or more, 10 mol% or more, 20 mol% or more, 30 mol% or more, 40 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, and 90 mol% or more relative to the total polymerized units. The content of the polymerized units (I) is particularly preferably substantially 100 mol%, and the polymer (I) is most preferably composed only of the polymerized units (I).

[0116] In the polymer (I), the content of the polymerization units based on other monomers copolymerizable with the monomer represented by the general formula (I) is, in order of preference, 99.0 mol% or less, 97.0 mol% or less, 95.0 mol% or less, 90 mol% or less, 80 mol% or less, 70 mol% or less, 60 mol% or less, 50 mol% or less, 40 mol% or less, 30 mol% or less, 20 mol% or less, and 10 mol% or less, based on the total polymerization units. It is particularly preferable that the content of the polymerization units based on other monomers copolymerizable with the monomer represented by the general formula (I) is substantially 0 mol%, and it is most preferable that the polymer (I) does not contain any polymerization units based on other monomers.

[0117] The number average molecular weight of the polymer (I) is 0.1×10 4 More than 0.2×10 is preferable. 4 More preferably, 0.3×10 4 More preferably, 0.4×10 4 More preferably, 0.5×10 4More preferably, 1.0×10 4 More than 3.0×10 is particularly preferable. 4 More particularly, 3.1×10 4 More than 75.0×10 is the most preferable. 4 Less than 50.0×10 is preferable. 4 Less than 40.0×10 is more preferable. 4 More preferably, 30.0×10 4 The following is particularly preferred: 20.0×10 4 The following is particularly preferred. The number average molecular weight and weight average molecular weight are values ​​calculated by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard. In addition, when measurement by GPC is not possible, the number average molecular weight of the polymer (I) can be determined from the correlation between the number average molecular weight calculated from the number of terminal groups obtained by NMR, FT-IR, etc. and the melt flow rate. The melt flow rate can be measured in accordance with JIS K 7210.

[0118] The lower limit of the weight average molecular weight of the polymer (I) is preferably 0.2×10 4 Above, 0.4×10 4 Above, 0.6×10 4 Above, 0.8 x 10 4 That's it, 1.0 x 10 4 That's it, 2.0 x 10 4 That's it, 5.0 x 10 4 That's it, 10.0 x 10 4 That's it, 15.0 x 10 4 That's it, 20.0 x 10 4 That's it, 25.0 x 10 4 The upper limit of the weight average molecular weight of the polymer (I) is, in order of preference, 150.0×10 4 Below, 100.0 x 10 4 Below, 60.0 x 10 4 Below, 50.0 x 10 4 Below, 40.0 x 10 4 The following is the result.

[0119] The polymer (I) preferably has an ion exchange ratio (IXR) of 53 or less, where IXR is defined as the number of carbon atoms in the polymer backbone relative to the ionic group. Precursor groups that become ionic upon hydrolysis (e.g., -SO2F) are not considered ionic groups for purposes of determining IXR.

[0120] IXR is preferably 0.5 or more, more preferably 1 or more, even more preferably 3 or more, even more preferably 4 or more, and particularly preferably 5 or more. IXR is more preferably 43 or less, even more preferably 33 or less, and particularly preferably 23 or less.

[0121] The ion exchange capacity of the polymer (I) is, in order of preference, 0.80 meq / g or more, 1.50 meq / g or more, 1.75 meq / g or more, 2.00 meq / g or more, 2.20 meq / g or more, more than 2.20 meq / g, 2.50 meq / g or more, 2.60 meq / g or more, 3.00 meq / g or more, and 3.50 meq / g or more. The ion exchange capacity is the content of ionic groups (anionic groups) in the polymer (I) and is calculated from the composition of the polymer (I).

[0122] In the polymer (I), the ionic (anionic) groups are typically distributed along the polymer backbone. The polymer (I) comprises a polymer backbone with recurring side chains attached to the backbone, which side chains preferably carry ionic groups.

[0123] The polymer (I) preferably comprises an ionic group having a pKa of less than 10, more preferably less than 7. The ionic group of the polymer (I) is preferably selected from the group consisting of sulfonate, carboxylate, phosphonate and phosphate.

[0124] The terms "sulfonate, carboxylate, phosphonate, and phosphate" are intended to refer to the respective salts or the respective acids capable of forming salts. When salts are used, preferably the salts are alkali metal or ammonium salts. A preferred ionic group is the sulfonate group.

[0125] The polymer (I) is preferably water-soluble. Water-soluble means the property of being easily dissolved or dispersed in an aqueous medium. The polymer (I) having water-solubility has a particle size that cannot be measured by dynamic light scattering (DLS), for example, or has a particle size of 5 nm or less.

[0126] The viscosity of an aqueous solution of polymer (I) is preferably 5.0 mPa.s or more, more preferably 8.0 mPa.s or more, even more preferably 10.0 mPa.s or more, particularly preferably 12.0 mPa.s or more, and most preferably 14.0 mPa.s or more, preferably 100.0 mPa.s or less, more preferably 50.0 mPa.s or less, even more preferably 25.0 mPa.s or less, and especially preferably 20.0 mPa.s or less.

[0127] The viscosity of the aqueous solution of polymer (I) can be determined by adjusting the content of polymer (I) in the aqueous solution to 33 mass % relative to the aqueous solution, and measuring the viscosity of the obtained aqueous solution at 20°C using a tuning fork vibro viscometer (model: SV-10) manufactured by A&D Corporation.

[0128] The critical micelle concentration (CMC) of the polymer (I) is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, and preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less.

[0129] The critical micelle concentration of the polymer (I) can be determined by measuring the surface tension. The surface tension can be measured, for example, by a surface tensiometer CBVP-A3 manufactured by Kyowa Interface Science Co., Ltd.

[0130] The acid value of the polymer (I) is preferably 60 or more, more preferably 90 or more, even more preferably 120 or more, particularly preferably 150 or more, and most preferably 180 or more. The upper limit is not particularly limited, but is preferably 300 or less.

[0131] The acid value of the polymer (I) is determined by the presence of an anionic group other than the acid functional group, such as -COOM. a , -SO3M a , -OSO3M a or C(CF3)2OM a (M a is a metal atom, NR 2 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 2 When the compound has an acid group (H or an organic group), these groups can be converted to acid-form groups and then measured by acid-base titration.

[0132] The polymer (I) is a polymer (11) of a monomer (11) represented by general formula (11), in which the content of polymerization units (11) based on the monomer (11) is 50 mol % or more based on all polymerization units constituting the polymer (11), and the weight average molecular weight (Mw) is 38.0×10 4 The above polymer (11) can also be used. General formula (11): CX2=CY-CF2-O-Rf-A (In the formula, X and Y are independently H, F, CH3 or CF3, and at least one of X and Y is F. Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. A is -COOM a , -SO3M a , -OSO3M a or C(CF3)2OM a (M a is H, metal atom, NR 2 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 2 is H or an organic group.

[0133] In the general formula (11), X and Y are independently H, F, CH3 or CF3, and at least one of X and Y is F. X is preferably H or F, and more preferably H. Y is preferably H or F, and more preferably F.

[0134] Rf and A in the general formula (11) are the same as Rf and A in the general formula (1) representing the monomer constituting the polymer (1).

[0135] The polymer (11) may be a homopolymer consisting of only polymerization units (11) based on the monomer (11), or may be a copolymer containing the polymerization units (11) and polymerization units based on other monomers copolymerizable with the monomer (11). The other monomers are as described above. The polymerization units (11) may be the same or different in each occurrence, and the polymer (11) may contain polymerization units (11) based on two or more different monomers represented by the general formula (11).

[0136] The content of the polymerized units (11) in the polymer (11) is, in order of preference, 50 mol % or more, 60 mol % or more, 70 mol % or more, 80 mol % or more, 90 mol % or more, and 99 mol % or more based on the total polymerized units constituting the polymer (11). It is particularly preferable that the content of the polymerized units (11) is substantially 100 mol %, and it is most preferable that the polymer (11) is composed only of the polymerized units (11).

[0137] In the polymer (11), the content of polymerization units based on other monomers copolymerizable with the monomer (11) is, in order of preference, 99.0 mol % or less, 97.0 mol % or less, 95.0 mol % or less, 90 mol % or less, 80 mol % or less, 70 mol % or less, 60 mol % or less, and 50 mol % or less, based on all polymerization units constituting the polymer (11). It is particularly preferable that the content of polymerization units based on other monomers copolymerizable with the monomer (11) is substantially 0 mol %, and it is most preferable that the polymer (11) does not contain polymerization units based on other monomers.

[0138] The lower limit of the weight average molecular weight of the polymer (11) is, in order of preference, 38.0×10 4 That's it, 40.0 x 10 4 The upper limit of the weight average molecular weight of the polymer (11) is, in order of preference, 150.0×10 4 Below, 100.0 x 10 4 Below, 60.0 x 10 4 It is.

[0139] The lower limit of the number average molecular weight of the polymer (11) is, in order of preference, 5.0×10 4 , 8.0×10 4 , 10.0×10 4 That's it, 12.0 x 10 4 The upper limit of the number average molecular weight of the polymer (11) is, in order of preference, 75.0×10 4 Below, 50.0 x 10 4 Below, 40.0 x 10 4 Below, 30.0 x 10 4 The following is the result.

[0140] The polymer (I) is a polymer (12) of a monomer (12) represented by general formula (12), in which the content of polymerization units (12) based on the monomer (12) is 50 mol % or more based on all polymerization units constituting the polymer (12), and the weight average molecular weight (Mw) is 1.4×10 4 The above polymer (12) can also be used. General formula (12): CX2=CX-O-Rf-A (In the formula, X is independently F or CF3, Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and having an ether bond or a keto group. A is -COOM a , -SO3M a , -OSO3M a or C(CF3)2OM a (M a is -H, metal atom, -NR 2 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 2is H or an organic group.

[0141] In the general formula (12), X is independently F or CF3. It is preferable that at least one X is F, and it is more preferable that all X are F.

[0142] Rf and A in the general formula (12) are the same as Rf and A in the general formula (2) representing the monomer constituting the polymer (2).

[0143] The polymer (12) may be a homopolymer consisting of only polymerized units (12) based on the monomer (12), or may be a copolymer containing polymerized units (12) and polymerized units based on other monomers copolymerizable with the monomer (12). The other monomers are as described above. The polymerized units (12) may be the same or different in each occurrence, and the polymer (12) may contain polymerized units (12) based on two or more different monomers represented by the general formula (12).

[0144] The content of the polymerized units (12) in the polymer (12) is, in order of preference, 40 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, and 99 mol% or more based on the total polymerized units constituting the polymer (12). It is particularly preferable that the content of the polymerized units (12) is substantially 100 mol%, and it is most preferable that the polymer (12) is composed only of the polymerized units (12).

[0145] In the polymer (12), the content of polymerization units based on other monomers copolymerizable with the monomer (12) is, in order of preference, 50 mol % or less, 40 mol % or less, 30 mol % or less, 20 mol % or less, 10 mol % or less, and 1 mol % or less, based on all polymerization units constituting the polymer (12). It is particularly preferable that the content of polymerization units based on other monomers copolymerizable with the monomer (12) is substantially 0 mol %, and it is most preferable that the polymer (12) does not contain polymerization units based on other monomers.

[0146] The lower limit of the weight average molecular weight (Mw) of the polymer (12) is, in order of preference, 1.4×10 4 That's it, 1.7 x 10 4 That's it, 1.9 x 10 4 That's it, 2.1 x 10 4 That's it, 2.3 x 10 4 That's it, 2.7 x 10 4 That's it, 3.1 x 10 4 That's it, 3.5 x 10 4 That's it, 3.9 x 10 4 That's it, 4.3 x 10 4 That's it, 4.7 x 10 4 That's it, 5.1 x 10 4 The upper limit of the weight average molecular weight (Mw) of the polymer (12) is, in order of preference, 150.0×10 4 Below, 100.0 x 10 4 Below, 60.0 x 10 4 Below, 50.0 x 10 4 Below, 40.0 x 10 4 The following is the result.

[0147] The lower limit of the number average molecular weight (Mn) of the polymer (12) is, in order of preference, 0.7×10 4 Above, 0.9 x 10 4 That's it, 1.0 x 10 4 That's it, 1.2 x 10 4 That's it, 1.4 x 10 4 That's it, 1.6 x 10 4 That's it, 1.8 x 10 4 The upper limit of the number average molecular weight (Mn) of the polymer (12) is, in order of preference, 75.0×10 4 Below, 50.0 x 10 4 Below, 40.0 x 10 4 Below, 30.0 x 10 4 Below, 20.0 x 10 4 The following is the result.

[0148] The molecular weight distribution (Mw / Mn) of the polymer (12) is preferably 3.0 or less, more preferably 2.4 or less, even more preferably 2.2 or less, particularly preferably 2.0 or less, and most preferably 1.9 or less.

[0149] When the polymer (12) contains the polymerization units (12) and the polymerization units based on other monomers copolymerizable with the monomer (12), the content of the polymerization units (12) based on the monomer (12) is preferably 40 to 60 mol %, more preferably 45 to 55 mol %, based on all the polymerization units constituting the polymer (12), and the content of the polymerization units based on other monomers is preferably 60 to 40 mol %, more preferably 55 to 45 mol %, based on all the polymerization units constituting the polymer (12). Such a constitution is particularly suitable when the polymerization units based on other monomers copolymerizable with the monomer (12) are polymerization units (M) based on a monomer represented by the general formula CFR=CR2.

[0150] When the polymer (12) contains the polymerization unit (12) and the polymerization unit based on the other monomer copolymerizable with the monomer (12), the alternation ratio between the polymerization unit (12) and the polymerization unit based on the other monomer copolymerizable with the monomer (12) is preferably 40% or more, more preferably 50% or more, even more preferably 60% or more, still more preferably 70% or more, particularly preferably 80% or more, and most preferably 90% or more. The alternation ratio may be, for example, 40 to 99%. Such a constitution is particularly suitable when the polymerization unit based on the other monomer copolymerizable with the monomer (12) is a polymerization unit (M) based on a monomer represented by the general formula CFR=CR2.

[0151] The alternation ratio of the polymerized unit (12) and the polymerized unit based on another monomer copolymerizable with the monomer (12) in the polymer (12) is 19 It can be determined by F-NMR analysis.

[0152] The polymer (I) can be produced by a conventional method except for using the above-mentioned monomers.

[0153] As the polymer (I), a polymer (13) of a monomer (13) represented by general formula (13), in which the content of the polymerization units (13) based on the monomer (13) is 50 mass% or more based on the total polymerization units constituting the polymer (13), can also be used. The polymer (13) is a novel polymer. General formula (13): CX2=CX-O-Rf-SO3M a (In the formula, X is independently F or CF3, and Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and having an ether bond or a keto group. M a is -H, metal atom, -NR 2 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 2 is H or an organic group.

[0154] In the general formula (13), X is independently F or CF3. It is preferable that at least one X is F, and it is more preferable that all X are F.

[0155] Rf and M in general formula (13) a is the same as Rf and A in the general formula (2) representing the monomer constituting the polymer (2).

[0156] The polymer (13) may be a homopolymer consisting of only polymerized units (13) based on the monomer (13), or may be a copolymer containing polymerized units (13) and polymerized units based on other monomers copolymerizable with the monomer (13). The other monomers are as described above. The polymerized units (13) may be the same or different in each occurrence, and the polymer (13) may contain polymerized units (13) based on two or more different monomers represented by the general formula (13).

[0157] The content of the polymerization units (13) based on the monomer (13) in the polymer (13) is 50% by mass or more based on all the polymerization units constituting the polymer (13). The content of the polymerization units (13) in the polymer (13) is, in order of preference, 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, and 99% by mass or more based on all the polymerization units constituting the polymer (13). It is particularly preferable that the content of the polymerization units (13) is substantially 100% by mass, and it is most preferable that the polymer (13) is composed only of the polymerization units (13).

[0158] In the polymer (13), the content of polymerization units based on other monomers copolymerizable with the monomer (13) is, in order of preference, 50 mass% or less, 40 mass% or less, 30 mass% or less, 20 mass% or less, 10 mass% or less, and 1 mass% or less, based on all polymerization units constituting the polymer (13). It is particularly preferable that the content of polymerization units based on other monomers copolymerizable with the monomer (13) is substantially 0 mass%, and it is most preferable that the polymer (13) does not contain polymerization units based on other monomers.

[0159] The lower limit of the number average molecular weight of the polymer (13) is, in order of preference, 0.3×10 4 Above, 0.4×10 4 Above, 0.5 x 10 4 That's it, 0.7 x 10 4 Above, 0.8 x 10 4 That's it, 1.0 x 10 4 That's it, 1.2 x 10 4 That's it, 1.4 x 10 4 , 1.6×10 4 That's it, 1.8 x 10 4 That's it, 2.0 x 10 4 That's it, 3.0 x 10 4 The upper limit of the number average molecular weight of the polymer (13) is, in order of preference, 75.0×10 4 Below, 50.0 x 10 4 Below, 40.0 x 10 4 Below, 30.0 x 10 4 Below, 20.0 x 10 4 The following is the result.

[0160] The lower limit of the weight average molecular weight of the polymer (13) is, in order of preference, 0.4×10 4 Above, 0.5 x 10 4 Above, 0.6×10 4 Above, 0.8 x 10 4 That's it, 1.0 x 10 4 That's it, 1.2 x 10 4 That's it, 1.4 x 10 4 That's it, 1.7 x 10 4 That's it, 1.9 x 10 4 That's it, 2.1 x 10 4 That's it, 2.3 x 10 4 That's it, 2.7 x 10 4 That's it, 3.1 x 10 4 That's it, 3.5 x 10 4 That's it, 3.9 x 10 4 That's it, 4.3 x 10 4 That's it, 4.7 x 10 4 That's it, 5.1 x 10 4 That's it, 10.0 x 10 4 That's it, 15.0 x 10 4 That's it, 20.0 x 10 4 That's it, 25.0 x 10 4 The upper limit of the weight average molecular weight of the polymer (13) is, in order of preference, 150.0×10 4 Below, 100.0 x 10 4 Below, 60.0 x 10 4 Below, 50.0 x 10 4 Below, 40.0 x 10 4 The following is the result.

[0161] The molecular weight distribution (Mw / Mn) of the polymer (13) is preferably 3.0 or less, 2.4 or less, 2.2 or less, 2.0 or less, 1.9 or less, 1.7 or less, 1.5 or less, 1.4 or less, and 1.3 or less.

[0162] The content of dimers and trimers of the monomer (I) represented by the general formula (I) is preferably 1.0 mass% or less, more preferably 0.1 mass% or less, even more preferably 0.01 mass% or less, particularly preferably 0.001 mass% or less, and most preferably 0.0001 mass% or less, based on the polymer (I).

[0163] The dimers and trimers can be removed by ultrafiltration, microfiltration, dialysis membrane treatment, or the like.

[0164] The content of the polymer compound in the TFE-based polymer composition of the present disclosure is preferably 0.01 mass% or more, more preferably 0.05 mass% or more, even more preferably 0.08 mass% or more, and preferably 5.0 mass% or less, more preferably 3.0 mass% or less, even more preferably 2.0 mass% or less, and even more preferably 1.0 mass% or less, based on the TFE-based polymer.

[0165] The content of the above polymer compound in the TFE-based polymer composition can be determined by solid-state NMR measurement. Further, WO 2014 / 099453, WO 2010 / 075497, WO 2010 / 075496, WO 2011 / 008381, WO 2009 / 055521, WO 1987 / 007619, JP 61-293476 A, WO 2010 / 075494, WO 2010 / 075359, WO 2012 / 082454, WO 2006 / 119224, WO 2013 / 085864, Measurement methods for each polymer are described in JP2012 / 082707, JP2012 / 082703, JP2012 / 082451, JP2006 / 135825, JP2004 / 067588, JP2009 / 068528, JP2004-075978A, JP2001-226436A, JP1992 / 017635A, JP2014 / 069165A, JP11-181009A, etc. As a method for measuring the content of the above-mentioned polymer compound, the measurement methods for each polymer described therein can be used.

[0166] The TFE-based polymer in the TFE-based polymer composition of the present disclosure may be a homopolymer of tetrafluoroethylene (TFE), or may be a TFE copolymer containing polymerization units based on TFE (TFE units) and polymerization units based on a modified monomer (hereinafter also referred to as "modified monomer units"). The homopolymer of TFE refers to a polymer in which the content of polymerized units based on modified monomers copolymerizable with TFE is less than 0.0001% by mass of the total polymerized units. The TFE copolymer contains 10% by mass or less of modified monomer units. The TFE-based polymer may be polytetrafluoroethylene (PTFE). The PTFE may be a homopolymer of TFE or a modified PTFE. The modified PTFE contains 99.0% by mass or more of TFE units and 1.0% by mass or less of modified monomer units. The modified PTFE may be composed only of TFE units and modified monomer units. The TFE copolymer may be a modified PTFE. As the TFE-based polymer, the above TFE copolymer is preferred, and the above modified PTFE is more preferred, from the viewpoints of further suppressing gas generation and deterioration of electrochemical device properties and improving the binding force, strength and flexibility of the mixture sheet.

[0167] The TFE copolymer preferably has a modified monomer unit content of 0.0001 to 10% by mass relative to the total polymerized units, from the viewpoint of further suppressing gas generation and deterioration of electrochemical device properties, and improving extensibility, binding force, strength and flexibility of the mixture sheet. The lower limit of the modified monomer unit content is more preferably 0.001% by mass, even more preferably 0.005% by mass, even more preferably 0.010% by mass, and even more preferably 0.015% by mass. The upper limit of the content of the modified monomer unit is preferably 5.0% by mass, more preferably 3.0% by mass, even more preferably 1.0% by mass, even more preferably 0.90% by mass, even more preferably 0.80% by mass, even more preferably 0.50% by mass, even more preferably 0.40% by mass, even more preferably 0.30% by mass, even more preferably 0.20% by mass, even more preferably 0.15% by mass, even more preferably 0.10% by mass, even more preferably 0.08% by mass, particularly preferably 0.05% by mass, and most preferably 0.03% by mass. In this specification, the modified monomer unit means a portion of the molecular structure of a TFE polymer that is derived from a modified monomer.

[0168] The content of each of the above-mentioned polymer units can be calculated by appropriately combining NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer.

[0169] The above-mentioned modified monomer is not particularly limited as long as it can be copolymerized with TFE, and examples thereof include perfluoroolefins such as hexafluoropropylene [HFP], hydrogen-containing fluoroolefins such as trifluoroethylene and vinylidene fluoride [VDF], perhaloolefins such as chlorotrifluoroethylene [CTFE], perfluorovinyl ethers, perfluoroallyl ethers, (perfluoroalkyl)ethylenes, ethylenes, etc. The modified monomers used may be one type or multiple types.

[0170] The perfluorovinyl ether is not particularly limited, and examples thereof include perfluorovinyl ethers represented by the following general formula (A): CF2=CF-ORf (A) (wherein Rf represents a perfluoro organic group). In this specification, the "perfluoro organic group" refers to an organic group in which all hydrogen atoms bonded to carbon atoms are replaced with fluorine atoms. The perfluoro organic group may have an ether oxygen.

[0171] An example of the perfluorovinyl ether is perfluoro(alkyl vinyl ether) [PAVE], where Rf in the general formula (A) is a perfluoroalkyl group having 1 to 10 carbon atoms. The number of carbon atoms in the perfluoroalkyl group is preferably 1 to 5.

[0172] Examples of the perfluoroalkyl group in the PAVE include a perfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, and a perfluorohexyl group.

[0173] The perfluorovinyl ether further includes those in which Rf in the above general formula (A) is a perfluoro(alkoxyalkyl) group having 4 to 9 carbon atoms, and those in which Rf is the following formula:

[0174] [ka]

[0175] (wherein m represents 0 or an integer of 1 to 4), Rf is a group represented by the following formula:

[0176] [ka]

[0177] (wherein n represents an integer of 1 to 4).

[0178] The (perfluoroalkyl)ethylene [PFAE] is not particularly limited, and examples thereof include (perfluorobutyl)ethylene [PFBE] and (perfluorohexyl)ethylene.

[0179] The perfluoroallyl ether may, for example, be a compound represented by the general formula (B): CF2=CF-CF2-ORf 1 (B) (In the formula, Rf 1 represents a perfluoro organic group.

[0180] Above Rf 1 is preferably a perfluoroalkyl group having 1 to 10 carbon atoms or a perfluoroalkoxyalkyl group having 1 to 10 carbon atoms. The perfluoroallyl ether is preferably at least one selected from the group consisting of CF2=CF-CF2-O-CF3, CF2=CF-CF2-O-C2F5, CF2=CF-CF2-O-C3F7, and CF2=CF-CF2-O-C4F9, more preferably at least one selected from the group consisting of CF2=CF-CF2-O-C2F5, CF2=CF-CF2-O-C3F7, and CF2=CF-CF2-O-C4F9, and further preferably CF2=CF-CF2-O-CF2CF2CF3.

[0181] As the modified monomer, from the viewpoint of improving the extensibility, binding strength, and flexibility of the composite sheet, at least one selected from the group consisting of PAVE, HFP, VDF, and CTFE is preferable, at least one selected from the group consisting of perfluoro(methyl vinyl ether) [PMVE], HFP, VDF, and CTFE is more preferable, and at least one selected from the group consisting of PMVE and HFP is more preferable.

[0182] The TFE polymer may have a core-shell structure. Examples of the TFE polymer having a core-shell structure include TFE copolymers having a core of a high molecular weight TFE polymer and a shell of a lower molecular weight TFE polymer or TFE copolymer in the particles. Examples of modified PTFE include those having a core of a high molecular weight PTFE and a shell of a lower molecular weight PTFE or modified PTFE in the particles. Examples of such modified PTFE include PTFE described in JP-A-2005-527652.

[0183] The TFE-based polymer preferably has an endothermic peak temperature of 320° C. or higher, more preferably 325° C. or higher, even more preferably 330° C. or higher, even more preferably 335° C. or higher, even more preferably 340° C. or higher, even more preferably 342° C. or higher, and particularly preferably 344° C. or higher, in that an electrode mixture sheet having even greater strength can be formed. The endothermic peak temperature is also preferably 350° C. or lower. The endothermic peak temperature is the temperature corresponding to the minimum point in the heat of fusion curve obtained by performing differential scanning calorimetry (DSC) at a heating rate of 10°C / min on a fluororesin that has not been heated to a temperature of 300°C or higher. When there are two or more minimum points in one melting peak, each of them is regarded as the endothermic peak temperature.

[0184] The TFE-based polymer preferably has one or more endothermic peaks in the range of 333 to 347°C in a heat of fusion curve when the temperature is increased at a rate of 10°C / min using a differential scanning calorimeter [DSC], and has a heat of fusion of 62 mJ / mg or more at 290 to 350°C calculated from the heat of fusion curve.

[0185] The TFE-based polymer has a number average molecular weight (Mn) of 0.5×10 in order to form an electrode mixture sheet having superior strength. 6 It is preferable that the value is equal to or greater than 1.0×10 6 More preferably, it is 1.5×10 6More preferably, it is 2.0×10 or more. 6 More preferably, it is 3.0×10 or more. 6 It is particularly preferable that the number average molecular weight is 20.0×10 or more. 6 It is preferable that the value is less than 15.0×10 6 More preferably, it is 12.0×10 6 More preferably, it is 10.0×10 6 Even more preferably, it is 8.0×10 or less. 6 It is particularly preferred that: The number average molecular weight is a molecular weight calculated from the heat of crystallization estimated by measuring the temperature drop of a melted fluororesin using a differential scanning calorimeter (DSC) according to the method described in the following document. The measurement is carried out five times, and the average value of the three values ​​excluding the maximum and minimum values ​​is used. Literature: Suwa, T.; Takehisa, M.; Machi, S., J. Appl. Polym. Sci. vol. 17, pp. 3253 (1973).

[0186] The TFE-based polymer composition of the present disclosure is substantially free of moisture. This can further suppress gas generation and deterioration of electrochemical device properties, and can also improve the strength of the composite sheet. In addition, it is advantageous in terms of production process because it is possible to select a wide range of electrode active materials and solid electrolytes to be combined. "Substantially free of moisture" means that the moisture content of the TFE-based polymer composition is 0.050% by mass or less. The water content is preferably 0.040% by mass or less, more preferably 0.020% by mass or less, even more preferably 0.010% by mass or less, even more preferably 0.005% by mass or less, and particularly preferably 0.002% by mass or less. The water content is measured by the following method. The mass of the TFE-based polymer composition is measured before and after heating at 150° C. for 2 hours, and calculated according to the following formula. A sample is taken three times, and the calculation is performed for each, and the average value is calculated and used. Water content (mass%)=[(mass (g) of TFE-based polymer composition before heating)−(mass (g) of TFE-based polymer composition after heating)] / (mass (g) of TFE-based polymer composition before heating)×100

[0187] The TFE-based polymer composition of the present disclosure preferably does not substantially contain a fluorine-containing compound having a molecular weight of not more than 1000. This makes it possible to suppress gas generation inside an electrochemical device cell and deterioration of the electrochemical device characteristics (for example, a decrease in capacity during storage at high temperatures) when the composition is used as a binder for an electrochemical device. The term "substantially free of fluorine-containing compounds" means that the amount of the fluorine-containing compounds is 25 ppb by mass or less based on the TFE polymer composition. The amount of the fluorine-containing compound is preferably less than 25 mass ppb, more preferably less than 10 mass ppb, even more preferably less than 10 mass ppb, even more preferably less than 5 mass ppb, even more preferably less than 3 mass ppb, even more preferably less than 1 mass ppb, and particularly preferably less than 1 mass ppb. The lower limit is not particularly limited, and may be less than the lower limit of quantification.

[0188] The amount of the fluorine-containing compound having a molecular weight of 1,000 or less is measured by the following method. Weigh out 1 g of the sample, add 10 g (12.6 ml) of methanol, and perform ultrasonic treatment for 60 minutes to obtain an extract. The resulting extract is concentrated using nitrogen purging as appropriate, and the fluorine-containing compounds in the concentrated extract are measured by LC / MS / MS. Molecular weight information is extracted from the obtained LC / MS spectrum, and a match with the structural formula of the candidate fluorine-containing compound is confirmed. Prepare aqueous solutions with five or more levels of content of the standard substance, perform LC / MS analysis of the aqueous solutions with each content, plot the relationship between the content and the area for that content, and draw a calibration curve. Using the above calibration curve, the area of ​​the LC / MS chromatogram of the fluorine-containing compounds in the extract is converted to the content of the fluorine-containing compounds. The lower limit of quantification in this measurement method is 10 ppb by mass.

[0189] The amount of the fluorine-containing compound having a molecular weight of 1000 or less can also be measured by the following method. Weigh out 1 g of the sample, add 10 g (12.6 ml) of methanol, and perform ultrasonic treatment at 60°C for 2 hours. After standing at room temperature, remove the solids to obtain an extract. The resulting extract is appropriately concentrated with nitrogen purging, and the fluorine-containing compounds in the concentrated extract are measured by LC / MS / MS. Molecular weight information is extracted from the obtained LC / MS spectrum, and a match with the structural formula of the candidate fluorine-containing compound is confirmed. Five levels of methanol standard solutions of fluorine-containing compounds with known concentrations are prepared, and measurements are performed using a liquid chromatograph mass spectrometer. A calibration curve is created using a first-order approximation from the methanol standard solution concentration and the peak integral value in each concentration range. The content of the fluorine-containing compound in the extract is measured from the above calibration curve, and the content of the fluorine-containing compound in the sample is converted. The lower limit of quantification in this measurement method is 1 ppb by mass.

[0190] Examples of the fluorine-containing compound having a molecular weight of 1000 or less include a fluorine-containing compound having a hydrophilic group and a molecular weight of 1000 g / mol or less. The molecular weight of the fluorine-containing compound is preferably 800 or less, and more preferably 500 or less. Polymer particles obtained by polymerization in the presence of a fluorine-containing surfactant usually contain a fluorine-containing surfactant in addition to a TFE-based polymer. In this specification, the fluorine-containing surfactant is one that is used during polymerization. The above-mentioned fluorine-containing compound having a molecular weight of 1000 or less may be a compound that is not added during polymerization, for example, a compound that is generated as a by-product during polymerization. In addition, when the fluorine-containing compound having a molecular weight of 1000 or less contains an anionic moiety and a cationic moiety, it means a compound containing fluorine in which the molecular weight of the anionic moiety is 1000 or less. The fluorine-containing compound having a molecular weight of 1000 or less does not include TFE-based polymers.

[0191] The hydrophilic group may be, for example, -COOM, -SO2M, or -SO3M, where -COOM, -SO3M (in each formula, M is H, a metal atom, NR 1 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 1 is H or an organic group.

[0192] As the fluorine-containing surfactant, a surfactant containing fluorine (anionic fluorine-containing surfactant) whose anionic moiety has a molecular weight of 1000 or less can also be used. The "anionic moiety" refers to the part of the fluorine-containing surfactant excluding the cation. For example, F(CF2) n1 In the case of COOM, "F(CF2) n1 The "COO" part. The anionic fluorine-containing surfactant may be a surfactant represented by the following general formula (N 0 ): X n0 -Rf n0 -Y 0 (N 0 ) (In the formula, X n0 is H, Cl or F. n0 Y is a linear, branched or cyclic alkylene group having 3 to 20 carbon atoms, in which some or all of the H's are substituted with F, and the alkylene group may contain one or more ether bonds, and some of the H's may be substituted with Cl. 0 is an anionic group. Y 0 The anionic group may be -COOM, -SO2M, or -SO3M, and may be -COOM or -SO3M. M is H, a metal atom, or NR 1 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 1 is H or an organic group. The metal atom includes alkali metals (Group 1), alkaline earth metals (Group 2), etc., such as Na, K, or Li. R 1 As the 1-10 may be an organic group of H or C 1-4 may be an organic group of H or C 1-4 The alkyl group may be: M is H, a metal atom or NR 1 4, H, an alkali metal (group 1), an alkaline earth metal (group 2) or NR 1 4, which may be H, Na, K, Li or NH4. Above Rf n0 may be one in which 50% or more of H is substituted with fluorine.

[0193] The above fluorine-containing surfactant may be one type of fluorine-containing surfactant, or a mixture containing two or more types of fluorine-containing surfactants.

[0194] Examples of the fluorine-containing surfactant include compounds represented by the following formula: The fluorine-containing surfactant may be a mixture of these compounds. F(CF2)7COOM, F(CF2)5COOM, H(CF2)6COOM, H(CF2)7COOM, CF3O(CF2)3OCHFCF2COOM, C3F7OCF(CF3)CF2OCF(CF3)COOM, CF3CF2CF2OCF(CF3)COOM, CF3CF2OCF2CF2OCF2COOM, C2F5OCF(CF3)CF2OCF(CF3)COOM, CF3OCF(CF3)CF2OCF(CF3)COOM, CF2ClCF2CF2OCF(CF3)CF2OCF2COOM, CF2ClCF2CF2OCF2CF(CF3)OCF2COOM, CF2ClCF(CF3)OCF(CF3)CF2OCF2COOM, CF2ClCF(CF3)OCF2CF(CF3)OCF2COOM, and [ka] (In each formula, M is H, metal atom, NR 1 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. 1 is H or an organic group. The TFE-based polymer composition of the present disclosure is preferably substantially free of any of the fluorine-containing compounds represented by the above formulas.

[0195] In each of the above formulas, M is H, a metal atom, or NR 1 4, H, an alkali metal (group 1), an alkaline earth metal (group 2) or NR 1 4, which may be H, Na, K, Li or NH4. R 1 is H or C 1-10 may be an organic group of H or C 1-4 may be an organic group of H or C 1-4 The alkyl group may be:

[0196] When the TFE-based polymer composition of the present disclosure is substantially free of any of the fluorine-containing compounds represented by the above formulas, gas generation and deterioration of electrochemical device properties can be further suppressed, and the strength of the composite sheet can be further improved. "Substantially free of any of the fluorine-containing compounds represented by the above formulas" means that the amount of the fluorine-containing compounds is 25 ppb by mass or less relative to the TFE-based polymer composition. The amount of the fluorine-containing compound is preferably less than 25 mass ppb, more preferably less than 10 mass ppb, even more preferably less than 10 mass ppb, even more preferably less than 5 mass ppb, even more preferably less than 3 mass ppb, even more preferably less than 1 mass ppb, and particularly preferably less than 1 mass ppb. The lower limit is not particularly limited, and may be less than the lower limit of quantification.

[0197] The TFE-based polymer compositions of the present disclosure have the following general formula: [C n-1 F 2n-1 COO - ]M + (In the formula, n is an integer of 9 to 14, preferably an integer of 9 to 12; M + represents a cation.) is also preferably substantially free of a fluorine-containing compound represented by the formula (I). This can further suppress gas generation and deterioration of electrochemical device properties, and can also further improve the strength of the composite sheet. The cation M in the above formula + The M in the above is the same as M described above. "Substantially free of the fluorine-containing compound represented by the above formula" means that the amount of the fluorine-containing compound is 25 ppb by mass or less based on the TFE-based polymer composition. The amount of the fluorine-containing compound is preferably less than 25 mass ppb, more preferably less than 10 mass ppb, even more preferably less than 10 mass ppb, even more preferably less than 5 mass ppb, even more preferably less than 3 mass ppb, even more preferably less than 1 mass ppb, and particularly preferably less than 1 mass ppb. The lower limit is not particularly limited, and may be less than the lower limit of quantification.

[0198] The TFE-based polymer composition of the present disclosure preferably consists essentially of the TFE-based polymer and the polymer compound. This allows the effects of the TFE-based polymer and the polymer compound to be significantly exhibited. "Substantially consists essentially of the TFE-based polymer and the polymer compound" means that the total amount of the TFE-based polymer and the polymer compound is 95.0% by mass or more relative to the TFE-based polymer composition. The total amount of the TFE polymer and the polymer compound is preferably 98.0 mass % or more, more preferably 99.0 mass % or more, even more preferably 99.5 mass % or more, particularly preferably 99.9 mass % or more, and most preferably 99.95 mass % or more, based on the TFE polymer composition.

[0199] The TFE-based polymer composition of the present disclosure preferably has non-melt secondary processability. The non-melt secondary processability means that the melt flow rate cannot be measured at a temperature higher than the melting point according to ASTM D-1238 and D-2116, in other words, that the composition does not flow easily even in the melting temperature range.

[0200] The TFE-based polymer composition of the present disclosure preferably has a standard specific gravity (SSG) of 2.280 or less, more preferably 2.250 or less, even more preferably 2.220 or less, even more preferably 2.200 or less, even more preferably 2.190 or less, especially preferably 2.180 or less, and particularly preferably 2.170 or less, in terms of being able to further suppress gas generation and deterioration of electrochemical device properties, and of improving extensibility, binding strength, and flexibility of a mixture sheet. The SSG is also preferably equal to or greater than 2.130. The SSG is measured by a water displacement method according to ASTM D 792 using a sample molded according to ASTM D 4895.

[0201] In terms of being able to further suppress gas generation and deterioration of electrochemical device properties, and of improving the binding force, strength and flexibility of a mixture sheet, the TFE-based polymer composition of the present disclosure has an extrusion pressure at a reduction ratio (RR) of 100 of preferably 10 MPa or more, more preferably 12 MPa or more, even more preferably 15 MPa or more, even more preferably 16 MPa or more, and particularly preferably 17 MPa or more. In terms of improving processability, the extrusion pressure in RR100 is preferably 50 MPa or less, more preferably 40 MPa or less, even more preferably 35 MPa or less, even more preferably 30 MPa or less, even more preferably 25 MPa or less, even more preferably 21 MPa or less, and particularly preferably 20 MPa or less.

[0202] The extrusion pressure in RR100 is determined by the following method in accordance with the method described in JP-A-2002-201217. 21.7 g of lubricant (trade name: Isopar H (registered trademark), manufactured by Exxon Corp.) is added to 100 g of the TFE-based polymer composition, and mixed in a glass bottle at room temperature for 3 minutes. The glass bottle is then left at room temperature (25°C) for at least 1 hour before extrusion to obtain a lubricated resin. The lubricated resin is paste-extruded at room temperature through an orifice (diameter 2.5 mm, land length 11 mm, introduction angle 30°) at a reduction ratio of 100:1 to obtain a uniform bead (extrusion molded body). The extrusion speed, i.e., the ram speed, is 20 inches / min (51 cm / min). The load when the extrusion load reaches equilibrium in the paste extrusion is measured, and the extrusion pressure is calculated by dividing the load by the cross-sectional area of ​​the cylinder used for the paste extrusion.

[0203] In terms of being able to further suppress gas generation and deterioration of electrochemical device properties, and of improving the binding force, strength and flexibility of the mixture sheet, the TFE-based polymer composition of the present disclosure has an extrusion pressure of preferably 18 MPa or more, more preferably 23 MPa or more, even more preferably 25 MPa or more, even more preferably 28 MPa or more, particularly preferably 30 MPa or more, and particularly preferably 32 MPa or more in RR300. The extrusion pressure in RR300 is preferably 45 MPa or less, and more preferably 40 MPa or less, in terms of improving processability.

[0204] The extrusion pressure in RR300 is measured by the following method. 50 g of TFE-based polymer powder and 10.25 g of hydrocarbon oil (trade name: Isopar G, Exxon) as an extrusion aid are mixed in a polyethylene container for 3 minutes. At room temperature (25°C), the above mixture is filled into the cylinder of an extruder, and a load of 0.47 MPa is applied to the piston inserted in the cylinder and held for 1 minute. The mixture is then extruded from the orifice at a ram speed of 18 mm / min. The ratio of the cross-sectional area of ​​the cylinder to the cross-sectional area of ​​the orifice (reduction ratio) is 300. In the latter half of the extrusion operation, the load (N) when the pressure reaches equilibrium is divided by the cross-sectional area of ​​the cylinder to determine the extrusion pressure (MPa).

[0205] The TFE-based polymer composition of the present disclosure is preferably stretchable, from the viewpoints of further suppressing gas generation and deterioration of electrochemical device properties, and improving the binding force, strength, and flexibility of the mixture sheet. Being stretchable means that a stretched body can be obtained in the following stretching test. The bead obtained by the paste extrusion at RR100 is heated at 230°C for 30 minutes to remove the lubricant from the bead. The bead is then cut to length, clamped at each end with a clamp distance of 1.5 inches (38 mm) apart, and heated to 300°C in an air circulating oven. The clamps are then separated at a desired speed (stretch rate) until a separation distance corresponding to the desired stretch (total stretch) is achieved, and a stretch test (stretch test) is performed. This stretch method essentially follows the method disclosed in U.S. Pat. No. 4,576,869, except for the extrusion speed (51 cm / min instead of 84 cm / min). "Stretch" is the increase in length due to stretching, usually expressed as a percentage of the original length. The stretch rate in the stretch method is 1000% / sec, and the total stretch is 2400%.

[0206] The TFE-based polymer composition of the present disclosure is preferably stretchable up to 24 times in terms of further suppressing gas generation and deterioration of electrochemical device properties, and further improving the binding force, strength and flexibility of the mixture sheet. Being stretchable 24 times means that the film does not break during stretching in the above stretching test.

[0207] In order to further improve the strength of the composite sheet, the TFE-based polymer composition of the present disclosure preferably has a breaking strength of 5 N or more, more preferably 10 N or more, and even more preferably 15 N or more. The upper limit of the breaking strength is not particularly limited, but may be, for example, 50 N or less. The breaking strength is a value determined by the following method. The stretched bead (produced by stretching the bead) obtained in the above-mentioned stretching test is clamped and fixed in a movable jaw having a gauge length of 5.0 cm, and a tensile test is performed at 25°C and a speed of 300 mm / min. The strength at the time of break is measured as the breaking strength.

[0208] The form of the TFE-based polymer composition of the present disclosure is not limited, but it is preferably a powder in that it can be mixed with an electrode active material and a solid electrolyte without using a large amount of a dispersion medium. The TFE polymer composition may be in a form other than a powder, for example, a dispersion.

[0209] The TFE polymer composition of the present disclosure preferably has an average primary particle diameter of 100 to 350 nm. When the average primary particle diameter is within the above range, the molecular weight of the TFE polymer is high, and the binding strength and flexibility of the mixture sheet are improved. The average primary particle diameter is more preferably 330 nm or less, even more preferably 320 nm or less, even more preferably 300 nm or less, even more preferably 280 nm or less, particularly preferably 250 nm or less, and more preferably 150 nm or more, even more preferably 170 nm or more, and even more preferably 200 nm or more. The average primary particle size is measured by the following method. The TFE-based aqueous dispersion is diluted with water until the solid content becomes 0.15% by mass, and the transmittance of the 550 nm projected light per unit length of the diluted latex obtained and the number-based length average particle diameter determined by measuring a specific direction using a transmission electron microscope photograph are measured to create a calibration curve. Using this calibration curve, the number-average particle diameter is determined from the measured transmittance of the 550 nm projected light for each sample, and is taken as the average primary particle diameter. The average primary particle size can also be measured by dynamic light scattering. In dynamic light scattering, a TFE-based polymer aqueous dispersion with a solid content of approximately 1.0% by mass is prepared, and measurements are taken at 25°C and 70 times cumulatively using an ELSZ-1000S (Otsuka Electronics Co., Ltd.). The refractive index of the solvent (water) is 1.3328, and the viscosity of the solvent (water) is 0.8878 mPa s.

[0210] The TFE-based polymer composition of the present disclosure may have an average secondary particle size of 350 μm or more, preferably 400 μm or more, more preferably 450 μm or more, even more preferably 500 μm or more, even more preferably 550 μm or more, and particularly preferably 600 μm or more, and is preferably 1000 μm or less, more preferably 900 μm or less, even more preferably 800 μm or less, and even more preferably 700 μm or less. The average secondary particle size is measured in accordance with JIS K 6891.

[0211] In terms of excellent handling, the TFE-based polymer composition of the present disclosure may have an average aspect ratio of 2.0 or less, preferably 1.8 or less, more preferably 1.7 or less, even more preferably 1.6 or less, even more preferably 1.5 or less, even more preferably 1.4 or less, especially preferably 1.3 or less, particularly preferably 1.2 or less, and most preferably 1.1 or less.The average aspect ratio may also be 1.0 or more. The above-mentioned average aspect ratio is determined by observing the TFE-based polymer composition or the TFE-based polymer aqueous dispersion diluted to a solid content of about 1 mass % with a scanning electron microscope (SEM), processing the images of 200 or more particles randomly sampled, and averaging the ratio of the major axis to the minor axis.

[0212] The TFE polymer composition of the present disclosure preferably contains fibrous particles having an aspect ratio of 1.5 or more in a proportion of 20 to 60% based on the total TFE polymer particles, in order to obtain a composite sheet having good moldability and high breaking strength. The ratio of the fibrous particles to the total particles can be calculated as follows. (1) The TFE-based polymer powder containing the fibrous particles is photographed with a scanning electron microscope (SEM). The photographing magnification can be, for example, 300 to 1000 times. (2) The captured image is imported into a computer, and all particles are separated into the above-mentioned fibrous particles and particles with an aspect ratio of less than 1.5 using image analysis software such as ImageJ. (3) The number of the fibrous particles is divided by the total number of particles, i.e., the sum of the number of the fibrous particles and the number of particles having an aspect ratio of less than 1.5, to calculate the ratio of the fibrous particles to the total number of particles. The fibrous particles having an aspect ratio of 1.5 or more are formed, for example, when the TFE-based polymer composition is mixed with an electrode active material or a solid electrolyte.

[0213] In terms of excellent handling properties, the TFE polymer composition of the present disclosure has an apparent density of preferably 0.40 g / ml or more, more preferably 0.43 g / ml or more, even more preferably 0.45 g / ml or more, even more preferably 0.48 g / ml or more, and particularly preferably 0.50 g / ml or more. The upper limit is not particularly limited, but may be 0.70 g / ml. The apparent density is measured in accordance with JIS K 6892.

[0214] The TFE-based polymer composition of the present disclosure can be suitably produced, for example, by a production method including a step (A) of polymerizing tetrafluoroethylene (TFE) in an aqueous medium in the presence of the polymer compound having an ionic group to obtain an aqueous dispersion containing the polymer compound, a TFE-based polymer, and an aqueous medium, a step (B) of coagulating the aqueous dispersion to obtain a wet powder, and a step (C) of drying the wet powder.

[0215] In the polymerization of step (A), the amount of the polymer compound added is preferably more than 0.02% by mass and not more than 10% by mass, more preferably 3% by mass, and even more preferably 1% by mass, relative to the aqueous medium. By setting the amount of the polymer compound added within the above range, the polymerization of the monomer in the aqueous medium can be smoothly carried out. The amount of the polymer compound added is the total amount of the polymer compound added in the polymerization.

[0216] In the polymerization, the polymer compound may be added all at once, or may be added continuously. The polymer compound may be added continuously, for example, not all at once, but over time, without interruption or in portions. In the polymerization, an aqueous solution containing the polymer compound and water may be prepared, and the aqueous solution may be added.

[0217] In the above polymerization, it is preferable to start adding the polymer compound before the solid content of the TFE polymer formed in the aqueous medium reaches 0.5% by mass, and to continue adding the polymer compound thereafter.The timing of starting the addition of the polymer compound is preferably before the solid content of the TFE polymer reaches 0.3% by mass, more preferably before it reaches 0.2% by mass, even more preferably before it reaches 0.1% by mass, and particularly preferably at the same time as the start of polymerization.The solid content is the content of the TFE polymer relative to the total of the aqueous medium and the TFE polymer.

[0218] In the above polymerization, if at least one of the above polymer compounds is used, it is possible to efficiently produce a TFE polymer. In addition, two or more of the compounds included in the above polymer compounds may be used simultaneously, and other surface active compounds other than the above polymer compounds may be used simultaneously as long as they are volatile or may remain in the molded product made of the TFE polymer.

[0219] In the above polymerization, a nucleating agent may be used. The amount of the nucleating agent added can be appropriately selected depending on the type of the nucleating agent. The amount of the nucleating agent added may be 5000 mass ppm or less, preferably 1000 mass ppm or less, more preferably 500 mass ppm or less, even more preferably 100 mass ppm or less, particularly preferably 50 mass ppm or less, and most preferably 10 mass ppm or less, based on the aqueous medium.

[0220] In the above polymerization, it is preferable to add a nucleating agent to the aqueous medium before the start of polymerization or before the solid content of the TFE-based polymer formed in the aqueous medium reaches 5.0 mass %. By adding the nucleating agent at the beginning of polymerization, an aqueous dispersion having a small average primary particle size and excellent stability can be obtained.

[0221] The amount of the nucleating agent added at the beginning of polymerization is preferably 5% by mass or less, more preferably 1.0% by mass or less, further preferably 0.5% by mass or less, and particularly preferably 0.1% by mass or less, based on the TFE-based polymer obtained. The lower limit of the amount of the nucleating agent added at the beginning of polymerization is not limited, but is, for example, 0.01 ppm by mass.

[0222] The use of a nucleating agent results in a TFE-based polymer having a smaller primary particle size compared to polymerization carried out in the absence of said nucleating agent.

[0223] Examples of the nucleating agent include dicarboxylic acids, perfluoropolyether (PFPE) acids or salts thereof, hydrocarbon-containing surfactants, etc. The nucleating agent preferably does not contain an aromatic ring and is preferably an aliphatic compound.

[0224] The nucleating agent is preferably added before or simultaneously with the addition of the polymerization initiator, but the particle size distribution can also be adjusted by adding it during the polymerization.

[0225] The amount of the dicarboxylic acid is preferably 1000 ppm by mass or less, more preferably 500 ppm by mass or less, and even more preferably 100 ppm by mass or less, relative to the aqueous medium.

[0226] The amount of the hydrocarbon-containing surfactant added is preferably 40 ppm by mass or less, more preferably 30 ppm by mass or less, and even more preferably 20 ppm by mass or less, based on the aqueous medium. It is presumed that the ppm amount of lipophilic nucleation sites present in the aqueous medium is less than the amount added. Therefore, the amount of the lipophilic nucleation sites is less than the above 40 ppm by mass, 30 ppm by mass, and 20 ppm by mass. Since the lipophilic nucleation sites are considered to exist as molecules, even a small amount of the hydrocarbon-containing surfactant can generate a large amount of lipophilic nucleation sites. Therefore, even if the hydrocarbon-containing surfactant is added to the aqueous medium at about 1 ppm by mass, a beneficial effect can be obtained. The preferred lower limit is 0.01 ppm by mass.

[0227] The hydrocarbon-containing surfactants include nonionic and cationic surfactants, including siloxane surfactants such as those disclosed in U.S. Pat. No. 7,897,682 (Brothers et al.) and U.S. Pat. No. 7,977,438 (Brothers et al.).

[0228] The hydrocarbon-containing surfactant is preferably a non-ionic surfactant (e.g., a non-ionic hydrocarbon surfactant). That is, the nucleating agent is preferably a non-ionic surfactant. The non-ionic surfactant preferably does not contain an aromatic moiety.

[0229] The nonionic surfactant may be any nonionic surfactant that may be contained in the composition to be concentrated.

[0230] In the above polymerization, a compound having a functional group capable of reacting by radical polymerization and a hydrophilic group may be used together with the polymer compound.

[0231] In the above polymerization, in addition to the above polymer compound and other compounds having surface activity that are used as desired, additives for stabilizing each compound can be used, such as a buffer, a pH adjuster, a stabilizing assistant, and a dispersion stabilizer.

[0232] As the stabilizing aid, paraffin wax, fluorine-based oil, fluorine-based solvent, silicone oil, etc. are preferable. The stabilizing aid may be used alone or in combination of two or more. As the stabilizing aid, paraffin wax is more preferable. The paraffin wax may be liquid, semi-solid, or solid at room temperature, but is preferably a saturated hydrocarbon having 12 or more carbon atoms. The melting point of the paraffin wax is usually preferably 40 to 65°C, more preferably 50 to 65°C.

[0233] The amount of the stabilizing aid used is preferably 0.1 to 12 mass %, more preferably 0.1 to 8 mass %, based on the mass of the aqueous medium used. It is desirable that the stabilizing aid is sufficiently hydrophobic and completely separated from the aqueous dispersion after polymerization so as not to become a contaminating component.

[0234] The polymerization is carried out by charging an aqueous medium, the polymer compound, monomers, and other additives as necessary into a polymerization reactor, stirring the contents of the reactor, and maintaining the reactor at a predetermined polymerization temperature, and then adding a predetermined amount of polymerization initiator to start the polymerization reaction. After the polymerization reaction starts, monomers, polymerization initiators, chain transfer agents, the polymer compound, and the like may be additionally added depending on the purpose. The polymer compound may be added after the polymerization reaction starts.

[0235] Usually, the polymerization temperature is 5 to 120° C., and the polymerization pressure is 0.05 to 10 MPaG. The polymerization temperature and polymerization pressure are appropriately determined depending on the type of monomer used, the molecular weight of the desired TFE-based polymer, and the reaction rate. The polymerization temperature may be varied during the polymerization, for example, to influence the molecular weight distribution, i.e., to obtain a broad molecular weight distribution or to obtain a bimodal or multimodal molecular weight distribution. The pH of the polymerization medium may be in the range of pH 2-11, preferably 3-10, most preferably 4-10.

[0236] The polymerization initiator is not particularly limited as long as it can generate radicals in the above polymerization temperature range, and known oil-soluble and / or water-soluble polymerization initiators can be used. Furthermore, it can also be combined with a reducing agent or the like to initiate polymerization as a redox. The concentration of the polymerization initiator is appropriately determined depending on the type of monomer, the molecular weight of the target TFE-based polymer, and the reaction rate.

[0237] As the polymerization initiator, an oil-soluble radical polymerization initiator or a water-soluble radical polymerization initiator can be used.

[0238] The water-soluble radical polymerization initiator may be a known water-soluble peroxide, and examples thereof include ammonium salts, potassium salts, and sodium salts of persulfuric acid, perboric acid, perchloric acid, perphosphoric acid, and percarbonic acid, organic peroxides such as disuccinic acid peroxide and diglutaric acid peroxide, t-butyl permaleate, t-butyl hydroperoxide, etc. A reducing agent such as sulfites may also be contained, and the amount used may be 0.1 to 20 times that of the peroxide.

[0239] For example, when polymerization is carried out at a low temperature of 30° C. or less, it is preferable to use a redox initiator that combines an oxidizing agent and a reducing agent as the polymerization initiator. Examples of the oxidizing agent include persulfates, organic peroxides, potassium permanganate, manganese triacetate, and cerium ammonium nitrate. Examples of the reducing agent include sulfites, bisulfites, bromates, diimines, and oxalic acid. Examples of the persulfates include ammonium persulfate and potassium persulfate. Examples of the sulfites include sodium sulfite and ammonium sulfite. In order to increase the decomposition rate of the initiator, it is also preferable to add a copper salt or an iron salt to the combination of the redox initiator. Examples of the copper salt include copper(II) sulfate, and examples of the iron salt include iron(II) sulfate.

[0240] Examples of the redox initiator include potassium permanganate / oxalic acid, ammonium persulfate / bisulfite / iron sulfate, manganese triacetate / oxalic acid, cerium ammonium nitrate / oxalic acid, bromate / bisulfite, and the like, with potassium permanganate / oxalic acid being preferred. When using a redox initiator, either an oxidizing agent or a reducing agent may be charged in advance into a polymerization tank, and then the other may be added continuously or intermittently to initiate polymerization. For example, when potassium permanganate / oxalic acid is used, it is preferred to charge oxalic acid into a polymerization tank and continuously add potassium permanganate thereto.

[0241] The amount of polymerization initiator to be added is not particularly limited, but may be added all at once, stepwise, or continuously in an amount (e.g., several ppm relative to water concentration) at least at which the polymerization rate does not drop significantly. The upper limit is a range in which the reaction temperature may be increased while removing heat from the equipment side by the polymerization reaction heat, and a more preferable upper limit is a range in which the polymerization reaction heat can be removed from the equipment side.

[0242] The aqueous medium is a reaction medium for polymerization, and refers to a liquid containing water. The aqueous medium is not particularly limited as long as it contains water, and may contain water and, for example, a fluorine-free organic solvent such as an alcohol, ether, or ketone, and / or a fluorine-containing organic solvent having a boiling point of 40° C. or less.

[0243] In the above polymerization, a known chain transfer agent, radical scavenger, or decomposer may be further added depending on the purpose to adjust the polymerization rate and molecular weight.

[0244] Examples of the chain transfer agent include esters such as dimethyl malonate, diethyl malonate, methyl acetate, ethyl acetate, butyl acetate, and dimethyl succinate, as well as isopentane, methane, ethane, propane, methanol, isopropanol, acetone, various mercaptans, various halogenated hydrocarbons such as carbon tetrachloride, cyclohexane, and the like.

[0245] Bromine compounds or iodine compounds may be used as chain transfer agents. Examples of polymerization methods using bromine compounds or iodine compounds include a method of polymerizing fluoromonomers in an aqueous medium in the presence of a bromine compound or iodine compound in a substantially oxygen-free state (iodine transfer polymerization method). Representative examples of bromine compounds or iodine compounds to be used include those represented by the general formula: R a I x Br y (In the formula, x and y are each an integer of 0 to 2, and 1≦x+y≦2 is satisfied; R a is a saturated or unsaturated fluorohydrocarbon group or chlorofluorohydrocarbon group having 1 to 16 carbon atoms, or a hydrocarbon group having 1 to 3 carbon atoms, which may contain an oxygen atom). By using a bromine compound or an iodine compound, iodine or bromine is introduced into the polymer and functions as a crosslinking point.

[0246] Examples of the bromine compound or iodine compound include 1,3-diiodoperfluoropropane, 2-iodoperfluoropropane, 1,3-diiodo-2-chloroperfluoropropane, 1,4-diiodoperfluorobutane, 1,5-diiodo-2,4-dichloroperfluoropentane, 1,6-diiodoperfluorohexane, 1,8-diiodoperfluorooctane, 1,12-diiodoperfluorododecane, 1,16-diiodoperfluorohexadecane, diiodomethane, 1,2-diiodoethane, 1,3-diiodo-n-propane, CF2Br2, BrCF2CF2Br, CF3CFBrCF2Br, CFClBr2, BrCF Examples of the iodoperfluoroalkyl group include 2CFClBr, CFBrClCFClBr, BrCF2CF2CF2Br, BrCF2CFBrOCF3, 1-bromo-2-iodoperfluoroethane, 1-bromo-3-iodoperfluoropropane, 1-bromo-4-iodoperfluorobutane, 2-bromo-3-iodoperfluorobutane, 3-bromo-4-iodoperfluorobutene-1, 2-bromo-4-iodoperfluorobutene-1, monoiodomonobromo-substituted benzene, diiodomonobromo-substituted benzene, and (2-iodoethyl) and (2-bromoethyl)-substituted benzene. These compounds may be used alone or in combination with each other.

[0247] Among these, it is preferable to use 1,4-diiodoperfluorobutane, 1,6-diiodoperfluorohexane, and 2-iodoperfluoropropane in terms of polymerization reactivity, crosslinking reactivity, availability, and the like.

[0248] The amount of the chain transfer agent used is usually 1 to 50,000 ppm by mass, and preferably 1 to 20,000 ppm by mass, based on the total amount of fluoromonomers supplied.

[0249] The chain transfer agent may be added to the reaction vessel all at once before the initiation of polymerization, may be added all at once after the initiation of polymerization, may be added in several divided portions during the polymerization, or may be added continuously during the polymerization.

[0250] As the polymerization initiator, persulfates (e.g., ammonium persulfate), disuccinic acid peroxide, diglutaric acid peroxide, and other organic peroxides can be used alone or in the form of a mixture thereof. They may also be used in combination with a reducing agent such as sodium sulfite to form a redox system. Furthermore, during polymerization, a radical scavenger such as hydroquinone or catechol, or a peroxide decomposer such as ammonium sulfite, can be added to adjust the radical concentration in the system.

[0251] In the above polymerization, a fluoropolymer may be obtained by polymerizing a fluoromonomer in an aqueous medium in the presence of the above polymer compound to produce an aqueous dispersion of fluoropolymer particles, and then seed-polymerizing the fluoromonomer to the fluoropolymer particles in the aqueous dispersion of fluoropolymer particles.

[0252] The above polymerization is preferably carried out by polymerizing a fluoromonomer in the substantial absence of a fluorine-containing surfactant (excluding compounds having a functional group and a hydrophilic group capable of reacting in radical polymerization). According to the above production method, a TFE-based polymer can be obtained even in the absence of a fluorine-containing surfactant.

[0253] In the present disclosure, "substantially in the absence of a fluorine-containing surfactant" means that the amount of the fluorine-containing surfactant relative to the aqueous medium is 10 ppm by mass or less. The amount of the fluorine-containing surfactant relative to the aqueous medium is preferably 1 ppm by mass or less, more preferably 100 ppb by mass or less, even more preferably 10 ppb by mass or less, even more preferably less than 10 ppb by mass, even more preferably 1 ppb by mass or less, and particularly preferably less than 1 ppb by mass.

[0254] Examples of the fluorine-containing surfactant include those mentioned above as the fluorine-containing surfactant that is preferably not substantially contained in the TFE polymer composition of the present disclosure.

[0255] The polymerization produces an aqueous dispersion containing a TFE polymer, the polymer compound, and an aqueous medium. The content (solid content) of the TFE polymer in the aqueous dispersion is usually 10 to 50% by mass, more preferably 15% by mass or more, and preferably 40% by mass or less, and more preferably 35% by mass or less.

[0256] The above-mentioned polymer compound may further be added to the above-mentioned aqueous dispersion.

[0257] The coagulation in step (B) can be carried out by a known method. When coagulation is performed on the aqueous dispersion of the TFE-based polymer, the aqueous dispersion obtained by polymerization of the polymer latex or the like is usually diluted with water to a polymer concentration of 10 to 25% by mass (preferably a polymer concentration of 10 to 20% by mass), and in some cases, the pH is adjusted to neutral or alkaline, and then the mixture is stirred more vigorously than during the reaction in a vessel equipped with a stirrer. The coagulation may be performed while stirring while adding a water-soluble organic compound such as methanol or acetone, an inorganic salt such as potassium nitrate or ammonium carbonate, or an inorganic acid such as hydrochloric acid, sulfuric acid, or nitric acid as a coagulant. The coagulation may also be performed continuously using an in-line mixer or the like.

[0258] In step (C), the drying is usually carried out by using a means such as vacuum, high frequency, or hot air while keeping the wet powder in a state where it is not very fluidized, preferably in a state where it is left stationary. Friction between powders, especially at high temperatures, generally has an undesirable effect on fine powder-type TFE polymers. This is because particles made of this type of TFE polymer have the property of easily fibrillating even with a small shear force and losing the original stable particle structure. The drying temperature is preferably 300° C. or less, more preferably 250° C. or less, even more preferably 230° C. or less, even more preferably 210° C. or less, even more preferably 190° C. or less, and particularly preferably 170° C. or less, from the viewpoint of reducing the extrusion pressure. From the viewpoint of improving the breaking strength, the temperature is preferably 10° C. or more, more preferably 100° C. or more, even more preferably 150° C. or more, even more preferably 170° C. or more, even more preferably 190° C. or more, and particularly preferably 210° C. or more. In order to further increase the strength ratio, it is preferable to appropriately adjust the temperature within this temperature range.

[0259] In step (C), it is preferable to place the wet powder obtained in step (B) in a container having air permeability at the bottom and / or sides, and heat-treat for 2 hours or more at a temperature of 130 to 300° C. By carrying out heat-treating under such extremely limited conditions, the fluorine-containing compound having a molecular weight of 1000 or less can be efficiently removed together with water, and the contents of the fluorine-containing compound and water can be within the above-mentioned ranges.

[0260] The temperature of the heat treatment in step (C) is preferably 140°C or higher, more preferably 150°C or higher, even more preferably 160°C or higher, even more preferably 180°C or higher, even more preferably 200°C or higher, particularly preferably 220°C or higher, and is preferably 280°C or lower, more preferably 250°C or lower, in order to more efficiently remove moisture and fluorine-containing compounds.

[0261] The time for the heat treatment in step (C) is preferably 5 hours or more, more preferably 10 hours or more, and even more preferably 15 hours or more, in terms of more efficiently removing moisture and fluorine-containing compounds. The upper limit is not particularly limited, but is, for example, preferably 100 hours, more preferably 50 hours, and even more preferably 30 hours.

[0262] The wind speed in step (C) is preferably 0.01 m / s or more, more preferably 0.03 m / s or more, even more preferably 0.05 m / s or more, and even more preferably 0.1 m / s or more, from the viewpoint of more efficiently removing moisture and fluorine-containing compounds, and is preferably 50 m / s or less, more preferably 30 m / s or less, and even more preferably 10 m / s or less, from the viewpoint of suppressing scattering of powder.

[0263] The heat treatment in step (C) can be carried out using an electric furnace or a steam furnace. For example, it can be carried out using electric furnaces such as a parallel flow box type electric furnace, a ventilated box type electric furnace, a ventilated conveyor type electric furnace, a band electric furnace, a radiant conveyor type electric furnace, a fluidized bed electric furnace, a vacuum electric furnace, an agitation type electric furnace, an airflow type electric furnace, a hot air circulation type electric furnace, or a steam furnace corresponding to the above (a device in which the electric furnace in the device name of each electric furnace is replaced with a steam furnace). In terms of being able to remove moisture more efficiently, a parallel flow box type electric furnace, a ventilated box type electric furnace, a ventilated conveyor type electric furnace, a band electric furnace, a fluidized bed electric furnace, a hot air circulation type electric furnace, or a steam furnace corresponding to the above (a device in which the electric furnace in the device name of each electric furnace is replaced with a steam furnace) is preferred.

[0264] The heat treatment in step (C) is preferably carried out by placing the wet powder in a container whose bottom and / or sides are air permeable, in order to more efficiently remove moisture and fluorine-containing compounds. The container whose bottom and / or sides are air permeable may be any container that can withstand the heat treatment temperature, and is preferably made of a metal such as stainless steel. The container having breathable bottom and / or sides is preferably a tray (bat) having breathable bottom and / or sides, and more preferably a tray having a mesh bottom and / or sides (mesh tray). The mesh is preferably either a woven mesh or a punched metal. The mesh size is preferably 2000 μm or less (ASTM standard 10 mesh or more), more preferably 595 μm or less (30 mesh or more), even more preferably 297 μm or less (50 mesh or more), even more preferably 177 μm or less (80 mesh or more), particularly preferably 149 μm or less (100 mesh or more), and particularly preferably 74 μm or less (200 mesh or more). Also, 25 μm or more (500 mesh or less) is preferable. When the mesh is a woven net, the weaving method may be, for example, plain weave, twill weave, plain tatami weave, or twill tatami weave. When the mesh is a punched metal, the aperture ratio is preferably 10% or more, more preferably 20% or more, and even more preferably 30% or more, and is preferably 95% or less.

[0265] In the step (C), the amount of the moist powder is preferably 10 g / cm from the viewpoint of more efficiently removing moisture and fluorine-containing compounds. 2 It is preferable that the thickness is less than 8 g / cm 2 More preferably, it is 5 g / cm or less. 2 More preferably, it is 3 g / cm or less. 2 It is particularly preferable that the density is 0.01 g / cm or less. 2 It is preferable that the concentration is 0.05 g / cm or more. 2 More preferably, it is 0.1 g / cm or more. 2 More preferably, it is equal to or greater than this.

[0266] The moisture content of the moist powder to be heat-treated in step (C) is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, relative to the moist powder, in order to more efficiently remove moisture and fluorine-containing compounds, and is preferably 150% by mass or less, and more preferably 100% by mass or less.

[0267] The TFE-based polymer composition of the present disclosure is used in a binder for electrochemical devices. In the binder for electrochemical devices, the TFE-based polymer composition of the present disclosure may be used alone or may be used in combination with other materials (e.g., polymers other than TFE-based polymers), but it is preferable to use the TFE-based polymer composition of the present disclosure substantially alone, and more preferable to use it alone. Note that, "using the TFE-based polymer composition of the present disclosure substantially alone" means that the amount of the TFE-based polymer composition in the binder for electrochemical devices is used within the range described below. The TFE-based polymer composition of the present disclosure is preferably used in a binder for a battery. The TFE-based polymer composition of the present disclosure can improve the strength of a composite sheet while maintaining good ion conductivity, and is therefore preferably used as a binder for secondary batteries, particularly as a binder for lithium ion secondary batteries and binders for solid secondary batteries, and is also preferably used as a binder for capacitors.

[0268] The present disclosure also provides a binder for electrochemical devices consisting essentially of a TFE-based polymer composition, the TFE-based polymer composition containing a TFE-based polymer and a polymer compound having an ionic group, and substantially free of moisture. The binder of the present disclosure contains a specific TFE-based polymer composition, and therefore can improve the strength of the composite sheet. In addition, since it contains substantially no moisture, it can suppress gas generation inside the electrochemical device cell and deterioration of the electrochemical device characteristics (for example, decrease in capacity during high-temperature storage). In addition, it is not necessary to use a large amount of a dispersion medium such as water or an organic solvent, and it is possible to select a wide range of electrode active materials and solid electrolytes to be combined, which is advantageous in terms of the production process. In addition, it is possible to reduce the process and cost due to the use of a dispersion medium. Furthermore, since the binder of the present disclosure has excellent binding strength with active materials and electrolytes, it is possible to reduce the amount of use.

[0269] As the TFE-based polymer composition in the binder of the present disclosure, the same TFE-based polymer composition as described above in the present disclosure can be used, and the preferred embodiments are also the same.

[0270] The binder of the present disclosure is substantially composed of the TFE-based polymer composition. This allows the effect of the TFE-based polymer composition to be significantly exhibited. "Substantially composed of the TFE-based polymer composition" means that the content of the TFE-based polymer composition is 95.0% by mass or more relative to the binder. The content of the TFE polymer composition relative to the binder is preferably 98.0% by mass or more, more preferably 99.0% by mass or more, even more preferably 99.5% by mass or more, particularly preferably 99.9% by mass or more, and most preferably 99.95% by mass or more. It is also preferred that the binder of the present disclosure consists solely of the TFE-based polymer composition.

[0271] The binder of the present disclosure is preferably substantially free of organic solvent. This can reduce the steps and costs involved in using organic solvents. "Substantially free of organic solvent" means that the organic solvent content of the binder is 5% by mass or less. The organic solvent content is preferably 3% by mass or less, more preferably 1% by mass or less, even more preferably 0.1% by mass or less, even more preferably 0.01% by mass or less, and particularly preferably 0.001% by mass or less.

[0272] The binder of the present disclosure is preferably in the form of a powder.

[0273] The binders of the present disclosure are used in electrochemical devices such as batteries and capacitors. The battery may be a secondary battery such as a lithium ion battery. The capacitor is not particularly limited, but is preferably an electrochemical capacitor. Examples of the electrochemical capacitor include an electric double layer capacitor, a hybrid capacitor, and a redox capacitor. Examples of the hybrid capacitor include a sodium ion capacitor, a lithium ion capacitor, and a magnesium ion capacitor. Among these, an electric double layer capacitor is particularly preferred.

[0274] The binder of the present disclosure can be suitably used as a binder for batteries, and can be particularly suitably used as a binder for secondary batteries such as lithium ion batteries, etc. In addition, since the binder can improve the strength of a composite sheet while maintaining good ion conductivity, it is also suitable as a binder for solid secondary batteries. The binders of the present disclosure may be used to fabricate electrochemical device components, preferably battery components. The binder of the present disclosure can be particularly suitably used as a binder for electrodes. The binder of the present disclosure can also be suitably used as a binder in the solid electrolyte layer of a solid secondary battery.

[0275] The present disclosure also provides an electrode mixture comprising the above-mentioned TFE-based polymer composition of the present disclosure or the binder of the present disclosure and an electrode active material. By using the electrode mixture of the present disclosure, an electrode can be obtained that can suppress gas generation inside an electrochemical device cell and deterioration of electrochemical device characteristics (for example, a decrease in capacity during high-temperature storage). In addition, the strength of the mixture sheet can be improved. In addition, even if the amount of binder is small, the electrode active material can be held, so that more materials that improve electrochemical device characteristics, such as active materials and conductive assistants, can be added.

[0276] The electrode active material includes a positive electrode active material and a negative electrode active material.

[0277] The positive electrode active material is not particularly limited as long as it can electrochemically absorb and release alkali metal ions, but for example, a material containing an alkali metal and at least one transition metal is preferable. Specific examples include an alkali metal-containing transition metal complex oxide and an alkali metal-containing transition metal phosphate compound. Among them, the positive electrode active material is preferably an alkali metal-containing transition metal complex oxide that produces high voltage. Examples of the alkali metal ion include lithium ion, sodium ion, potassium ion, etc. In a preferred embodiment, the alkali metal ion may be a lithium ion. That is, in this embodiment, the alkali metal ion secondary battery is a lithium ion secondary battery.

[0278] Examples of the alkali metal-containing transition metal composite oxide include: Formula: M a Mn 2-b M 1 b O4 (Wherein, M is at least one metal selected from the group consisting of Li, Na, and K; 0.9≦a; 0≦b≦1.5; M 1 is at least one metal selected from the group consisting of Fe, Co, Ni, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si and Ge), Formula:MNi 1-c M 2 c O2 (Wherein, M is at least one metal selected from the group consisting of Li, Na, and K; 0≦c≦0.5; M 2 is at least one metal selected from the group consisting of Fe, Co, Mn, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si and Ge), or Formula:MCo 1-d M 3 d O2 (Wherein, M is at least one metal selected from the group consisting of Li, Na, and K; 0≦d≦0.5; M 3 at least one metal selected from the group consisting of Fe, Ni, Mn, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge) and alkali metal-cobalt composite oxides (lithium-cobalt composite oxides, etc.). In the above, M is preferably one metal selected from the group consisting of Li, Na and K, more preferably Li or Na, and even more preferably Li.

[0279] Among these, MCoO2, MMnO2, MNiO2, MMn2O4, and MNi are the most popular because they can provide high energy density and high output secondary batteries. 0.8 Co 0.15 Al 0.05 O2 or MNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 and the like are preferred, and a compound represented by the following general formula (3) is preferred. MNi h Co i Mn j M 5 k O2(3) (In the formula, M is at least one metal selected from the group consisting of Li, Na, and K, and M 5 represents at least one selected from the group consisting of Fe, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge, and (h+i+j+k)=1.0, 0≦h≦1.0, 0≦i≦1.0, 0≦j≦1.5, and 0≦k≦0.2.

[0280] The alkali metal-containing transition metal phosphate compound is, for example, a compound represented by the following general formula (4): M e M 4 f (PO4) g (4) (In the formula, M is at least one metal selected from the group consisting of Li, Na, and K, and M 4represents at least one selected from the group consisting of V, Ti, Cr, Mn, Fe, Co, Ni and Cu, and 0.5≦e≦3, 1≦f≦2, 1≦g≦3. In the above, M is preferably one metal selected from the group consisting of Li, Na and K, more preferably Li or Na, and even more preferably Li. That is, the alkali metal-containing transition metal phosphate compound is preferably a lithium-containing transition metal phosphate compound.

[0281] The transition metal of the lithium-containing transition metal phosphate compound is preferably V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc., and specific examples include iron phosphates such as LiFePO4, Li3Fe2(PO4)3, LiFeP2O7, cobalt phosphates such as LiCoPO4, and lithium transition metal phosphate compounds in which a part of the transition metal atoms that constitute the main part of these lithium transition metal phosphate compounds is replaced with other elements such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, Si, etc. The lithium-containing transition metal phosphate compound is preferably one having an olivine structure.

[0282] Other examples of the positive electrode active material include lithium-nickel-based composite oxides. The lithium-nickel-based composite oxides are represented by the following general formula (5): Li y Ni 1-x M x O2(5) (wherein x is 0.01≦x≦0.7, y is 0.9≦y≦2.0, and M is a metal atom (excluding Li and Ni)) is preferred.

[0283] Other positive electrode active materials include MFePO4 and MNi 0.8 Co 0.2 O2, M 1.2 Fe 0.4 Mn 0.4 O2, MNi 0.5 Mn 1.5 O2, MV3O6, M2MnO3, etc. In particular, M2MnO3, MNi 0.5 Mn1.5 Positive electrode active materials such as O2 are preferable in that their crystal structures do not collapse even when the secondary battery is operated at a voltage exceeding 4.4 V or at a voltage of 4.6 V or higher. Therefore, an electrochemical device such as a secondary battery using a positive electrode material containing the positive electrode active material exemplified above is preferable because the residual capacity hardly decreases even when stored at a high temperature, the resistance increase rate hardly changes, and the battery performance does not deteriorate even when operated at a high voltage.

[0284] As other positive electrode active materials, solid solution materials such as M2MnO3 and M 6 O2 (wherein M is at least one metal selected from the group consisting of Li, Na, and K, and M 6 is a transition metal such as Co, Ni, Mn, Fe, etc.) can also be mentioned.

[0285] Examples of the solid solution material include, for example, an alkali metal manganate represented by the general formula Mx[Mn (1-y) M 7 y O z . Here, M in the formula is at least one metal selected from the group consisting of Li, Na, and K, and M 7 consists of at least one metal element other than M and Mn, and includes, for example, one or more elements selected from the group consisting of Co, Ni, Fe, Ti, Mo, W, Cr, Zr, and Sn. Also, the values of x, y, and z in the formula are in the ranges of 1 < x < 2, 0 ≤ y < 1, and 1.5 < z < 3. Among them, a manganese-containing solid solution material in which LiNiO2 or LiCoO2 is solid-solved based on Li2MnO3 such as Li 1.2 Mn 0.5 Co 0.14 Ni 0.14 O2 is preferable in that it can provide an alkali metal ion secondary battery having a high energy density.

[0286] In addition, it is preferable to include lithium phosphate in the positive electrode active material, since the continuous charging characteristics are improved. Although there is no limitation on the use of lithium phosphate, it is preferable to use the positive electrode active material and lithium phosphate mixed together. The amount of lithium phosphate used is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more, with respect to the total of the positive electrode active material and lithium phosphate, and is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less.

[0287] In addition, a substance having a different composition may be attached to the surface of the positive electrode active material. Examples of the surface-attaching substance include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide, sulfates such as lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, and aluminum sulfate, carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate, and carbon.

[0288] These surface-attaching substances can be attached to the surface of the positive electrode active material by, for example, a method of dissolving or suspending in a solvent, impregnating and adding to the positive electrode active material, and drying, a method of dissolving or suspending a surface-attaching substance precursor in a solvent, impregnating and adding to the positive electrode active material, and then reacting by heating, etc., a method of adding to a positive electrode active material precursor and simultaneously baking, etc. When carbon is attached, a method of mechanically attaching carbonaceous material in the form of, for example, activated carbon, etc., afterwards can also be used.

[0289] The amount of the surface-attached substance is preferably 0.1 ppm or more, more preferably 1 ppm or more, and even more preferably 10 ppm or more, and preferably 20% or less, more preferably 10% or less, and even more preferably 5% or less, by mass relative to the positive electrode active material. The surface-attached substance can suppress the oxidation reaction of the electrolyte on the surface of the positive electrode active material and can improve the battery life, but if the amount of attachment is too small, the effect is not fully manifested, and if it is too large, the ingress and egress of lithium ions is inhibited, which may increase the resistance.

[0290] The shape of the particles of the positive electrode active material may be any of the conventional shapes such as block, polyhedron, sphere, oval sphere, plate, needle, column, etc. Primary particles may be aggregated to form secondary particles.

[0291] The tap density of the positive electrode active material is preferably 0.5 g / cm 3 More preferably, 0.8 g / cm 3 More preferably, 1.0 g / cm 3 That is all. If the tap density of the positive electrode active material is below the lower limit, the amount of dispersion medium required during the formation of the positive electrode active material layer increases, and the amount of conductive material and binder required also increases, restricting the filling rate of the positive electrode active material in the positive electrode active material layer and possibly restricting the battery capacity. By using a composite oxide powder with a high tap density, a high density positive electrode active material layer can be formed. Generally, the higher the tap density, the better, and there is no particular upper limit, but if it is too high, the diffusion of lithium ions in the positive electrode active material layer using the electrolyte as a medium becomes rate-limiting, and the load characteristics may be easily deteriorated, so that the upper limit is preferably 4.0 g / cm. 3 Less than or equal to 3.7 g / cm 3 More preferably, 3.5 g / cm 3 The following is the result. The above tap density is the powder packing density (tap density) g / cm when 5 to 10 g of the positive electrode active material powder is placed in a 10 ml glass measuring cylinder and tapped 200 times with a stroke of approximately 20 mm. 3 is required.

[0292] The median diameter d50 of the particles of the positive electrode active material (secondary particle diameter when primary particles are aggregated to form secondary particles) is preferably 0.3 μm or more, more preferably 0.5 μm or more, even more preferably 0.8 μm or more, and most preferably 1.0 μm or more, and is preferably 30 μm or less, more preferably 27 μm or less, even more preferably 25 μm or less, and most preferably 22 μm or less. If it is below the lower limit, a high tap density product may not be obtained, and if it exceeds the upper limit, it may take time for lithium to diffuse within the particles, resulting in problems such as a decrease in battery performance. Here, by mixing two or more of the above positive electrode active materials having different median diameters d50, the filling property during positive electrode production can be further improved.

[0293] The median diameter d50 is measured by a known laser diffraction / scattering type particle size distribution analyzer. When using HORIBA's LA-920 as the particle size distribution analyzer, a 0.1% by mass aqueous solution of sodium hexametaphosphate is used as the dispersion medium for the measurement, and the measurement is performed after ultrasonic dispersion for 5 minutes with a measurement refractive index set to 1.24.

[0294] In the case where the primary particles are aggregated to form secondary particles, the average primary particle diameter of the positive electrode active material is preferably 0.05 μm or more, more preferably 0.1 μm or more, and even more preferably 0.2 μm or more, and the upper limit is preferably 5 μm or less, more preferably 4 μm or less, even more preferably 3 μm or less, and most preferably 2 μm or less. If the upper limit is exceeded, it is difficult to form spherical secondary particles, which may adversely affect the powder packing property or greatly reduce the specific surface area, and therefore the battery performance such as output characteristics may be likely to decrease. On the other hand, if the lower limit is exceeded, problems such as poor reversibility of charge and discharge may occur due to underdeveloped crystals. The average primary particle diameter is measured by observation using a scanning electron microscope (SEM). Specifically, in a photograph at a magnification of 10,000 times, the longest intercept value of a horizontal line at the left and right boundaries of a primary particle is determined for any 50 primary particles, and the average value is calculated.

[0295] The BET specific surface area of ​​the positive electrode active material is preferably 0.1 m 2 / g or more, more preferably 0.2m 2 / g or more, more preferably 0.3m 2 / g or more, and the upper limit is preferably 50m 2 / g or less, more preferably 40m 2 / g or less, more preferably 30m 2 If the BET specific surface area is smaller than this range, the battery performance is likely to decrease, whereas if it is larger, it is difficult to increase the tap density, and problems may easily occur in the processability when forming the positive electrode active material layer. The BET specific surface area is defined as a value measured by a nitrogen adsorption BET one-point method using a gas flow method, using a surface area meter (e.g., a fully automatic surface area measuring device manufactured by Okura Riken Co., Ltd.) after pre-drying a sample at 150°C for 30 minutes under a nitrogen flow and then using a nitrogen / helium mixed gas accurately adjusted so that the relative pressure of nitrogen to atmospheric pressure is 0.3.

[0296] When the secondary battery of the present disclosure is used as a large-sized lithium-ion secondary battery for hybrid vehicles or distributed power sources, high output is required, so it is preferable that the particles of the positive electrode active material are mainly secondary particles. The particles of the positive electrode active material preferably have an average secondary particle diameter of 40 μm or less and contain 0.5 to 7.0 volume % of fine particles having an average primary particle diameter of 1 μm or less. By containing fine particles having an average primary particle diameter of 1 μm or less, the contact area with the electrolyte is increased, and the diffusion of lithium ions between the electrode mixture and the electrolyte can be made faster, resulting in improved output performance of the battery.

[0297] The manufacturing method of the positive electrode active material is a general method for manufacturing inorganic compounds.In particular, various methods can be considered for manufacturing spherical or elliptical active materials, such as dissolving or pulverizing and dispersing the raw material of transition metal in a solvent such as water, adjusting the pH while stirring to produce and recover a spherical precursor, drying this as necessary, adding a Li source such as LiOH, Li2CO3, LiNO3, and baking at high temperature to obtain an active material.

[0298] For the production of the positive electrode, the positive electrode active material may be used alone, or two or more of different compositions may be used in any combination or ratio. In this case, a preferred combination is LiCoO2 and LiNi 0.33 Co 0.33 Mn 0.33 Examples of such a combination include a combination with a ternary system such as O2, a combination of LiCoO2 and LiMn2O4 or a combination in which a portion of the Mn is replaced with another transition metal, or a combination of LiFePO4 and LiCoO2 or a combination in which a portion of the Co is replaced with another transition metal.

[0299] The content of the positive electrode active material is preferably 50 to 99.5% by mass of the positive electrode mixture, more preferably 80 to 99% by mass, in terms of high battery capacity. The content in the positive electrode active material layer is preferably 80% by mass or more, more preferably 82% by mass or more, and particularly preferably 84% by mass or more. The upper limit is preferably 99% by mass or less, more preferably 98% by mass or less. If the content of the positive electrode active material in the positive electrode active material layer is low, the electric capacity may be insufficient. Conversely, if the content is too high, the strength of the positive electrode may be insufficient.

[0300] The negative electrode active material is not particularly limited, and examples thereof include lithium metal, artificial graphite, graphite carbon fiber, resin-sintered carbon, pyrolytic vapor-grown carbon, coke, mesocarbon microbeads (MCMB), furfuryl alcohol resin-sintered carbon, polyacene, pitch-based carbon fiber, vapor-grown carbon fiber, natural graphite, and carbonaceous materials such as non-graphitizable carbon, silicon-containing compounds such as silicon and silicon alloys, Li4Ti5O 12Among them, those containing at least a carbonaceous material and silicon-containing compounds are particularly suitable.

[0301] The negative electrode active material used in the present disclosure preferably contains silicon as a constituent element. By using the negative electrode active material containing silicon as a constituent element, a high-capacity battery can be produced.

[0302] The silicon-containing material is preferably silicon particles, particles having a structure in which fine silicon particles are dispersed in a silicon-based compound, silicon oxide particles represented by the general formula SiOx (0.5≦x≦1.6), or a mixture thereof. By using these, a negative electrode mixture for a lithium ion secondary battery having a higher initial charge / discharge efficiency, a high capacity, and excellent cycle characteristics can be obtained.

[0303] Silicon oxide in the present disclosure is a general term for amorphous silicon oxide, and silicon oxide before disproportionation is represented by the general formula SiOx (0.5≦x≦1.6). x is preferably 0.8≦x<1.6, and more preferably 0.8≦x<1.3. This silicon oxide can be obtained, for example, by heating a mixture of silicon dioxide and metallic silicon to produce silicon monoxide gas, which is then cooled and precipitated.

[0304] Particles having a structure in which silicon particles are dispersed in a silicon-based compound can be obtained, for example, by a method of baking a mixture of silicon particles and a silicon-based compound, or by heat treating silicon oxide particles before disproportionation represented by the general formula SiOx in an inert non-oxidizing atmosphere such as argon at a temperature of 400°C or higher, preferably 800 to 1,100°C, to perform a disproportionation reaction. In particular, the material obtained by the latter method is preferable because the silicon microcrystals are uniformly dispersed. The size of the silicon nanoparticles can be made 1 to 100 nm by the above-mentioned disproportionation reaction. Note that the silicon oxide in the particles having a structure in which silicon nanoparticles are dispersed in silicon oxide is preferably silicon dioxide. Note that it is possible to confirm that silicon nanoparticles (crystals) are dispersed in amorphous silicon oxide by a transmission electron microscope.

[0305] The physical properties of the silicon-containing particles can be appropriately selected depending on the composite particles to be produced. For example, the average particle size is preferably 0.1 to 50 μm, and the lower limit is more preferably 0.2 μm or more, and even more preferably 0.5 μm or more. The upper limit is more preferably 30 μm or less, and even more preferably 20 μm or less. The average particle size is expressed as the weight average particle size measured by a particle size distribution measurement using a laser diffraction method.

[0306] BET specific surface area is 0.5 to 100 m 2 / g is preferable, and 1 to 20m 2 / g is more preferable. 2 / g or more, there is no risk of the adhesiveness decreasing when processed into an electrode, which may result in a decrease in battery characteristics. 2 / g or less, the proportion of silicon dioxide on the particle surface becomes large, and there is no risk of a decrease in battery capacity when used as a negative electrode material for a lithium ion secondary battery.

[0307] The silicon-containing particles are coated with carbon to impart electrical conductivity, which leads to improved battery characteristics. Methods for imparting electrical conductivity include mixing the silicon-containing particles with conductive particles such as graphite, coating the surfaces of the silicon-containing particles with a carbon coating, and combining both of these methods. The carbon coating method is preferred, and chemical vapor deposition (CVD) is more preferred.

[0308] In order to increase the capacity of the resulting electrode mixture, the content of the negative electrode active material is preferably 40% by mass or more, more preferably 50% by mass or more, and particularly preferably 60% by mass or more in the electrode mixture, and the upper limit is preferably 99% by mass or less, more preferably 98% by mass or less.

[0309] The electrode mixture of the present disclosure preferably further contains a conductive assistant. Any known conductive material can be used as the conductive assistant. Specific examples include metal materials such as copper and nickel, graphite such as natural graphite and artificial graphite, carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black, and carbon materials such as needle coke, carbon nanotubes, fullerene, and amorphous carbon such as VGCF. These may be used alone or in any combination and ratio of two or more.

[0310] The conductive assistant is used in an electrode mixture so that it is contained in an amount of usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 1% by mass or more, and usually 50% by mass or less, preferably 30% by mass or less, more preferably 15% by mass or less. If the content is lower than this range, the conductivity may be insufficient. Conversely, if the content is higher than this range, the battery capacity may decrease.

[0311] The electrode mixture of the present disclosure may further contain a thermoplastic resin. Examples of the thermoplastic resin include polyvinylidene fluoride, polypropylene, polyethylene, polystyrene, polyethylene terephthalate, polyethylene oxide, etc. One type may be used alone, or two or more types may be used in any combination and ratio.

[0312] The ratio of the thermoplastic resin to the electrode active material is usually 0.01% by mass or more, preferably 0.05% by mass or more, more preferably 0.10% by mass or more, and usually 3.0% by mass or less, preferably 2.5% by mass or less, more preferably 2.0% by mass or less. The addition of the thermoplastic resin can improve the mechanical strength of the electrode. If the ratio exceeds this range, the ratio of the electrode active material in the electrode mixture decreases, which may cause problems such as a decrease in the battery capacity or an increase in the resistance between the active materials.

[0313] In the electrode mixture of the present disclosure, the content of the binder may be 0.1% by mass or more, preferably 0.2% by mass or more, more preferably 0.5% by mass or more, and may be 50% by mass or less, preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 10% by mass or less, particularly preferably 5% by mass or less, and most preferably 3% by mass or less. If the proportion of the binder is too low, the electrode mixture active material cannot be sufficiently held, and the mechanical strength of the electrode mixture sheet may be insufficient, which may deteriorate the battery performance such as cycle characteristics. On the other hand, if the proportion is too high, it may lead to a decrease in battery capacity and conductivity. Since the binder of the present disclosure has excellent binding strength, even if the content is small, the electrode active material can be sufficiently held.

[0314] In the electrode mixture of the present disclosure, the binder component is preferably substantially composed of the TFE-based polymer composition, and more preferably is composed of the TFE-based polymer composition. The binder component is substantially composed of the TFE-based polymer composition, which means that the content of the TFE-based polymer composition in the binder component constituting the electrode mixture is 95.0% by mass or more relative to the binder component. The content of the TFE-based polymer composition is preferably 98.0% by mass or more relative to the binder component, more preferably 99.0% by mass or more, even more preferably 99.5% by mass or more, particularly preferably 99.9% by mass or more, and most preferably 99.95% by mass or more.

[0315] The electrode mixture of the present disclosure is preferably in the form of a sheet.

[0316] The electrode mixture of the present disclosure can be suitably used as an electrode mixture for a secondary battery. In particular, the electrode mixture of the present disclosure is suitable for a lithium ion secondary battery. When used in a secondary battery, the electrode mixture of the present disclosure is usually used in a sheet form.

[0317] The electrode mixture sheet has a thickness of preferably 300 μm or less, more preferably 250 μm or less, even more preferably 200 μm or less, even more preferably 180 μm or less, particularly preferably 150 μm or less, and preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more.

[0318] An example of a specific method for producing an electrode mixture sheet containing an electrode mixture is shown below. The electrode mixture sheet can be obtained by a production method including a step (1) of mixing a raw material composition containing an electrode active material, a binder, and, if necessary, a conductive assistant, a step (2) of forming the raw material composition obtained in the step (1) into a bulk form, and a step (3) of rolling the bulk raw material composition obtained in the step (2) into a sheet form.

[0319] At the stage where the raw material composition is mixed in the above step (1), the raw material composition is present in a state without a fixed shape, with the electrode active material, binder, etc. simply being mixed together. Specific mixing methods include mixing methods using a W-type mixer, V-type mixer, drum mixer, ribbon mixer, conical screw mixer, single-shaft kneader, twin-shaft kneader, mix muller, stirring mixer, planetary mixer, etc.

[0320] In the above step (1), the binder mixing condition is preferably 3000 rpm or less. It is preferably 10 rpm or more, more preferably 15 rpm or more, and even more preferably 20 rpm or more, and is preferably 2000 rpm or less, more preferably 1500 rpm or less, and even more preferably 1000 rpm or less. If it is below the above range, mixing takes a long time, which affects productivity. On the other hand, if it is above the above range, fibrillation may proceed excessively, resulting in an electrode mixture sheet with poor strength and flexibility.

[0321] In the above step (2), forming into a bulk shape refers to forming the raw material composition into a single mass. Specific methods for forming into a bulk shape include extrusion molding, press molding, and the like. In addition, the "bulk shape" does not specify a particular shape, and may be in the form of a single mass, and includes shapes such as rods, sheets, spheres, and cubes.

[0322] Specific examples of the rolling method in the above step (3) include rolling methods using a roll press, a plate press, a calendar roll machine, or the like.

[0323] It is also preferable to have a step (4) after step (3) in which a larger load is applied to the obtained rolled sheet to roll it into an even thinner sheet. It is also preferable to repeat step (4). In this way, the rolled sheet is not thinned all at once, but is rolled little by little in stages, thereby improving flexibility. The number of times of step (4) is preferably 2 to 10 times, and more preferably 3 to 9 times. Specific rolling methods include, for example, a method in which two or more rolls are rotated and the rolled sheet is passed between them to process it into a thinner sheet.

[0324] From the viewpoint of adjusting the fibril diameter, it is also preferable to have a step (5) after the step (3) or the step (4) of roughly crushing the rolled sheet, forming it into a bulk shape again, and rolling it into a sheet. It is also preferable to repeat the step (5). The number of times of the step (5) is preferably 1 to 12 times, more preferably 2 to 11 times.

[0325] In step (5), specific methods for roughly crushing the rolled sheet and forming it into a bulk shape include folding the sheet, forming it into a rod or thin sheet shape, chipping, etc. In this disclosure, "rough crushing" means changing the shape of the rolled sheet obtained in step (3) or step (4) into a different shape in order to roll it into a sheet shape in the next step, and also includes the case where the rolled sheet is simply folded.

[0326] In addition, step (4) may be performed after step (5), or may be performed repeatedly. In addition, uniaxial or biaxial stretching may be performed in steps (2), (3), (4), and (5). In addition, the fibril diameter can be adjusted by the degree of crushing in step (5).

[0327] In the above steps (3), (4) or (5), the rolling ratio is preferably 10% or more, more preferably 20% or more, and is preferably 80% or less, more preferably 65% ​​or less, and even more preferably 50% or less. If it is below the above range, the number of times of rolling increases, which takes time and affects productivity. If it is above the above range, fibrillation may proceed excessively, resulting in an electrode mixture sheet with poor strength and flexibility. The rolling ratio here refers to the reduction rate of the thickness of the sample after processing relative to the thickness before rolling. The sample before rolling may be a bulk-shaped raw material composition or a sheet-shaped raw material composition. The thickness of the sample refers to the thickness in the direction in which a load is applied during rolling.

[0328] The electrode mixture sheet is Step (a): mixing a powder component and a binder to form an electrode mixture; Step (b): Calendaring or extrusion molding the electrode mixture to produce a sheet; Including, The mixing in step (a) is (a1) homogenizing the powder components and the binder to form a powder; (a2) mixing the powdered raw material mixture obtained in step (a1) to prepare an electrode mixture; It can also be suitably produced by a production method comprising the steps of:

[0329] For example, PTFE has two transition temperatures at about 19°C and about 30°C. Below 19°C, PTFE can be easily mixed while still maintaining its shape. However, above 19°C, the structure of the PTFE particles becomes loose and more sensitive to mechanical shear. At temperatures above 30°C, a greater degree of fibrillation occurs.

[0330] For this reason, the homogenization in (a1) is preferably carried out at a temperature of 19°C or lower, preferably from 0°C to 19°C. That is, in such (a1), it is preferable to mix and homogenize while suppressing fibrillation. The subsequent mixing step (a2) is preferably carried out at a temperature of 30° C. or higher to promote fibrillation.

[0331] The above step (a2) is carried out at a temperature of preferably 30°C to 150°C, more preferably 35°C to 120°C, and even more preferably 40°C to 80°C. In one embodiment, the calendaring or extrusion of step (b) above is carried out at a temperature between 30°C and 150°C, preferably between 35°C and 120°C, more preferably between 40°C and 100°C.

[0332] The mixing in the above step (a) is preferably carried out while applying a shear force. Specific mixing methods include methods using a W-type mixer, V-type mixer, drum mixer, ribbon mixer, conical screw mixer, single-shaft kneader, twin-shaft kneader, Mix Muller, stirring mixer, planetary mixer, Henschel mixer, high-speed mixer, etc.

[0333] The mixing conditions may be appropriately set by the number of revolutions and the mixing time. For example, the number of revolutions is preferably 15,000 rpm or less. It is preferably 10 rpm or more, more preferably 50 rpm or more, and even more preferably 100 rpm or more, and is preferably 12,000 rpm or less, more preferably 10,000 rpm or less, and even more preferably 8,000 rpm or less. If it is below the above range, it will take a long time to mix, which will affect productivity. If it is above the above range, fibrillation will proceed excessively, and the electrode mixture sheet may have poor strength. The step (a1) is preferably carried out with a weaker shear force than the step (a2). Moreover, it is preferable that step (a1) is carried out for a shorter time than step (a2).

[0334] In the above step (a2), the raw material composition preferably does not contain a liquid solvent, but a small amount of a lubricant may be used. That is, a lubricant may be added to the powdered raw material mixture obtained in the above step (a1) to prepare a paste.

[0335] The lubricant is not particularly limited, and examples thereof include water, ether compounds, alcohols, ionic liquids, carbonates, aliphatic hydrocarbons (low polarity solvents such as heptane and xylene), isoparaffinic hydrocarbon compounds, and petroleum fractions (gasoline (C4-C10), naphtha (C4-C11), kerosene / paraffin (C10-C16), and mixtures thereof).

[0336] The lubricant preferably has a water content of 1000 ppm or less. A moisture content of 1000 ppm or less is preferable in terms of reducing deterioration of the electrochemical device, and the moisture content is more preferably 500 ppm or less.

[0337] When the above-mentioned lubricant is used, it is particularly preferable that the lubricant is a solvent having low polarity, such as butyl butyrate, or an ether compound.

[0338] When the above lubricant is used, the amount thereof may be 5.0 to 35.0 parts by weight, preferably 10.0 to 30.0 parts by weight, and more preferably 15.0 to 25.0 parts by weight, based on the total weight of the composition used in step (a1).

[0339] It is preferable that the raw material composition does not substantially contain a liquid medium. In the conventional electrode mixture forming method, a solvent in which a binder is dissolved is used to prepare a slurry in which powder, which is an electrode mixture component, is dispersed, and the electrode mixture sheet is prepared by applying and drying the slurry. In this case, a solvent that disperses or dissolves the binder is used. However, the solvent that can dissolve the binder resin that has been generally used in the past is limited to a specific solvent such as N-methylpyrrolidone. Since the solvent has high polarity and requires a drying process, the use of the solvent generates processes and costs. In addition, these react with electrolytes such as electrolytic solutions and solid electrolytes to deteriorate the electrolyte, so that the residual components during slurry preparation or after drying may cause a decrease in battery performance. In addition, the binder resin that dissolves in low polarity solvents such as heptane is very limited, and the flash point is low, making handling complicated.

[0340] By using a powder binder with low moisture content without using a solvent when forming the electrode mixture sheet, a battery with little electrolyte deterioration can be manufactured. Furthermore, in the above-mentioned manufacturing method, an electrode mixture sheet containing a binder having a fine fiber structure can be manufactured, and by not preparing a slurry, the burden of the manufacturing process can be reduced.

[0341] Step (b) is calendering or extrusion. Calendering and extrusion can be performed by a known method. By this, it is possible to form the electrode mixture sheet into a shape. The step (b) preferably includes the steps of (b1) forming the electrode mixture obtained in the step (a) into a bulk form, and (b2) calendaring or extrusion molding the bulk form of the electrode mixture.

[0342] Forming into a bulk form means forming the electrode mixture into a single mass. Specific methods for forming the material into a bulk form include extrusion molding, press molding, and the like. In addition, the term "bulk" does not specify a particular shape, and may refer to a state in which the material is in the form of a single mass, including rods, sheets, spheres, cubes, etc. The size of the mass is preferably such that the diameter or the smallest side of the cross section is 10,000 μm or more, more preferably 20,000 μm or more.

[0343] A specific example of the calendering or extrusion molding method in the above step (b2) is a method in which the electrode mixture is rolled using a roll press machine, a calender roll machine or the like.

[0344] The above step (b) is preferably carried out at 30 to 150° C. As described above, PTFE has a glass transition temperature around 30° C., and therefore is easily fibrillated at temperatures of 30° C. or higher. Therefore, the step (b) is preferably carried out at such a temperature.

[0345] And, calendaring or extrusion applies a shear force, which fibrillates the PTFE and forms it into a shape.

[0346] It is also preferable to have a step (c) after step (b) in which a larger load is applied to the obtained rolled sheet to roll it into a thinner sheet. It is also preferable to repeat step (c). In this way, the rolled sheet is not thinned all at once, but is rolled little by little in stages, thereby improving flexibility. The number of times of step (c) is preferably from 2 to 10, and more preferably from 3 to 9. A specific rolling method includes, for example, a method in which a rolled sheet is passed between two or more rotating rolls to process it into a thinner sheet.

[0347] From the viewpoint of adjusting the sheet strength, it is also preferable to have a step (d) after the step (b) or the step (c) of crushing the rolled sheet, forming it into a bulk shape again, and rolling it into a sheet shape. It is also preferable to repeat the step (d). The number of times of the step (d) is preferably 1 to 12 times, more preferably 2 to 11 times.

[0348] In step (d), specific methods for roughly crushing the rolled sheet and forming it into a bulk shape include folding the rolled sheet, forming it into a rod or thin sheet shape, chipping, etc. In this disclosure, "rough crushing" means changing the shape of the rolled sheet obtained in step (b) or (c) into another shape in order to roll it into a sheet shape in the next step, and also includes the case where the rolled sheet is simply folded.

[0349] Furthermore, step (c) may be carried out after step (d), or may be carried out repeatedly. Moreover, uniaxial or biaxial stretching may be carried out in steps (a), (b), (c) and (d). Furthermore, the sheet strength can also be adjusted by the degree of coarse crushing in step (d).

[0350] In the above steps (b), (c) or (d), the rolling ratio is preferably 10% or more, more preferably 20% or more, and is preferably 80% or less, more preferably 65% ​​or less, and even more preferably 50% or less. If the rolling ratio is below the above range, the number of rolling times increases and it takes time, which affects productivity. If the rolling ratio is above the above range, fibrillation may proceed excessively, resulting in an electrode mixture sheet with poor strength and flexibility. The rolling ratio here refers to the reduction rate of the thickness of the sample after rolling to the thickness before rolling. The sample before rolling may be a bulk raw material composition or a sheet-like raw material composition. The thickness of the sample refers to the thickness in the direction in which a load is applied during rolling. The above steps (c) and (d) are preferably carried out at 30° C. or higher, more preferably 60° C. or higher, and preferably at 150° C. or lower.

[0351] The electrode mixture sheet can be used as an electrode mixture sheet for a secondary battery. It can be used for either a negative electrode or a positive electrode. In particular, the electrode mixture sheet is suitable for a lithium ion secondary battery.

[0352] The present disclosure also provides an electrode comprising the above-mentioned TFE-based polymer composition of the present disclosure or the binder of the present disclosure, an electrode active material, and a current collector. The electrode of the present disclosure can suppress gas generation inside an electrochemical device cell and deterioration of electrochemical device characteristics (for example, decrease in capacity during high-temperature storage). It also has excellent strength.

[0353] The electrode of the present disclosure may include the above-mentioned electrode mixture of the present disclosure (preferably an electrode mixture sheet) and a current collector.

[0354] The electrodes of the present disclosure may be positive electrodes or negative electrodes.

[0355] The positive electrode is preferably composed of a current collector and an electrode mixture sheet containing the positive electrode active material. The material of the positive electrode current collector includes metals such as aluminum, titanium, tantalum, stainless steel, nickel, and the like, and metal materials such as alloys thereof; carbon materials such as carbon cloth and carbon paper. Among them, metal materials, particularly aluminum or its alloys, are preferred.

[0356] The shape of the current collector may be metal foil, metal cylinder, metal coil, metal plate, expanded metal, punched metal, foam metal, etc. in the case of metal materials, and carbon plate, carbon thin film, carbon cylinder, etc. in the case of carbon materials. Among these, metal foil is preferred. The metal foil may be appropriately formed into a mesh shape. The thickness of the metal foil is optional, but is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and usually 1 mm or less, preferably 100 μm or less, more preferably 50 μm or less. If the metal foil is thinner than this range, the strength required as a current collector may be insufficient. Conversely, if the metal foil is thicker than this range, the handling may be impaired.

[0357] In addition, it is also preferable that the surface of the current collector is coated with a conductive assistant from the viewpoint of reducing the electrical contact resistance between the current collector and the positive electrode active material layer. Examples of the conductive assistant include carbon and precious metals such as gold, platinum, and silver.

[0358] The positive electrode may be manufactured by a conventional method, for example, a method in which the above-mentioned electrode mixture sheet and a current collector are laminated with an adhesive therebetween, and then vacuum dried.

[0359] The density of the positive electrode mixture sheet is preferably 2.80 g / cm 3 More preferably, 3.00 g / cm 3 More preferably, 3.20 g / cm 3 or more, and preferably 3.80 g / cm 3 Less than or equal to 3.75 g / cm 3 More preferably, 3.70 g / cm 3 The range is as follows. If the range is exceeded, the permeability of the electrolyte to the vicinity of the current collector / active material interface will decrease, and the charge / discharge characteristics, especially at high current density, will decrease, and high output may not be obtained. If the range is exceeded, the conductivity between the active materials will decrease, and the battery resistance will increase, and high output may not be obtained.

[0360] The thickness of the positive electrode is not particularly limited, but from the viewpoint of high capacity and high output, the thickness of the mixture layer minus the thickness of the metal foil of the current collector is, as a lower limit, preferably 10 μm or more, more preferably 20 μm or more, and also preferably 500 μm or less, more preferably 450 μm or less, on one side of the current collector.

[0361] The negative electrode is preferably composed of a current collector and an electrode mixture sheet containing the negative electrode active material. The material of the current collector for the negative electrode includes metals such as copper, nickel, titanium, tantalum, and stainless steel, or metal materials such as alloys thereof; and carbon materials such as carbon cloth and carbon paper. Among them, metal materials, particularly copper, nickel, or alloys thereof, are preferred.

[0362] The shape of the current collector may be metal foil, metal cylinder, metal coil, metal plate, expanded metal, punched metal, foam metal, etc. in the case of metal materials, and carbon plate, carbon thin film, carbon cylinder, etc. in the case of carbon materials. Among these, metal foil is preferred. The metal foil may be appropriately formed into a mesh shape. The thickness of the metal foil is optional, but is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and usually 1 mm or less, preferably 100 μm or less, more preferably 50 μm or less. If the metal foil is thinner than this range, the strength required as a current collector may be insufficient. Conversely, if the metal foil is thicker than this range, the handling may be impaired.

[0363] The negative electrode may be produced by a conventional method, for example, a method in which the above-mentioned electrode mixture sheet and a current collector are laminated with an adhesive therebetween, and then vacuum dried.

[0364] The density of the negative electrode mixture is preferably 1.3 g / cm 3 More preferably, 1.4 g / cm 3 More preferably, 1.5 g / cm 3 More preferably, it is 2.0 g / cm 3 Less than or equal to 1.9 g / cm 3 More preferably, 1.8 g / cm 3 The range is as follows. If the range is exceeded, the permeability of the electrolyte to the vicinity of the current collector / active material interface will decrease, and the charge / discharge characteristics, especially at high current density, will decrease, and high output may not be obtained. If the range is exceeded, the conductivity between the active materials will decrease, and the battery resistance will increase, and high output may not be obtained.

[0365] The thickness of the negative electrode is not particularly limited, but from the viewpoint of high capacity and high output, the thickness of the mixture layer minus the thickness of the metal foil of the current collector is, as a lower limit, preferably 10 μm or more, more preferably 20 μm or more, and also preferably 500 μm or less, more preferably 450 μm or less on one side of the current collector.

[0366] The present disclosure also provides a secondary battery comprising the electrode of the present disclosure described above.

[0367] The secondary battery of the present disclosure may be a secondary battery using an electrolytic solution or may be a solid secondary battery. In this specification, the solid secondary battery may be a secondary battery containing a solid electrolyte, may be a semi-solid secondary battery containing a solid electrolyte and a liquid component as the electrolyte, or may be an all-solid secondary battery containing only a solid electrolyte as the electrolyte.

[0368] The secondary battery using the above-mentioned electrolyte may use electrolytes, separators, etc. that are used in known secondary batteries. These will be described in detail below.

[0369] The electrolyte is preferably a non-aqueous electrolyte, which may be prepared by dissolving a known electrolyte salt in a known organic solvent for dissolving electrolyte salts.

[0370] The organic solvent for dissolving the electrolyte salt is not particularly limited, and one or more of known hydrocarbon solvents such as propylene carbonate, ethylene carbonate, butylene carbonate, γ-butyrolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; and fluorine-based solvents such as fluoroethylene carbonate, fluoroethers, and fluorinated carbonates can be used.

[0371] Examples of the electrolyte salt include LiClO4, LiAsF6, LiBF4, LiPF6, LiN(SO2CF3)2, and LiN(SO2C2F5)2. From the viewpoint of good cycle characteristics, LiPF6, LiBF4, LiN(SO2CF3)2, LiN(SO2C2F5)2, or combinations thereof are particularly preferred.

[0372] The concentration of the electrolyte salt is preferably 0.8 mol / L or more, more preferably 1.0 mol / L or more. The upper limit depends on the organic solvent for dissolving the electrolyte salt, but is usually 1.5 mol / L.

[0373] The secondary battery using the above-mentioned electrolyte preferably further includes a separator. The material and shape of the separator are not particularly limited as long as they are stable to the electrolyte and have excellent liquid retention, and any known separator can be used. Among them, it is preferable to use a material formed of a material stable to the electrolyte, such as a resin, glass fiber, or inorganic material, and to use a porous sheet or nonwoven fabric having excellent liquid retention.

[0374] Examples of materials that can be used for the resin and glass fiber separator include polyolefins such as polyethylene and polypropylene, aromatic polyamides, polytetrafluoroethylene, polyethersulfone, and glass filters. These materials may be used alone or in any combination and ratio, such as polypropylene / polyethylene two-layer film and polypropylene / polyethylene / polypropylene three-layer film. Among these, the separator is preferably a porous sheet or nonwoven fabric made of polyolefins such as polyethylene and polypropylene, because of its excellent electrolyte permeability and shutdown effect.

[0375] The thickness of the separator is arbitrary, but is usually 1 μm or more, preferably 5 μm or more, more preferably 8 μm or more, and is usually 50 μm or less, preferably 40 μm or less, more preferably 30 μm or less. If the separator is thinner than the above range, the insulating properties and mechanical strength may be reduced. If the separator is thicker than the above range, not only may the battery performance such as rate characteristics be reduced, but also the energy density of the entire electrolyte battery may be reduced.

[0376] On the other hand, examples of inorganic materials that can be used include oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates such as barium sulfate and calcium sulfate, and these are in particulate or fibrous form.

[0377] As for the form, a thin film such as a nonwoven fabric, a woven fabric, or a microporous film is used. In the thin film form, a film with a pore size of 0.01 to 1 μm and a thickness of 5 to 50 μm is preferably used. In addition to the above independent thin film form, a separator can be used in which a composite porous layer containing the above inorganic particles is formed on the surface layer of a positive electrode and / or a negative electrode using a resin binder. For example, a porous layer can be formed on both sides of a positive electrode using alumina particles with a 90% particle size of less than 1 μm and a fluororesin as a binder.

[0378] The material of the exterior case is not particularly limited as long as it is a material stable against the electrolyte used. Specifically, metals such as nickel-plated steel plate, stainless steel, aluminum or aluminum alloy, magnesium alloy, or a laminate film of resin and aluminum foil (laminate film) are used. From the viewpoint of weight reduction, metals such as aluminum or aluminum alloy, and laminate film are preferably used.

[0379] In the case of an exterior case using metals, there are cases in which the metals are welded together by laser welding, resistance welding, or ultrasonic welding to form a sealed structure, or cases in which the metals are used via a resin gasket to form a crimped structure. In the case of an exterior case using the laminate film, there are cases in which the resin layers are heat-sealed together to form a sealed structure. In order to improve the sealing property, a resin different from the resin used in the laminate film may be interposed between the resin layers. In particular, when the resin layer is heat-sealed via a current collecting terminal to form a sealed structure, the joining between the metal and the resin is performed, so that a resin having a polar group or a modified resin into which a polar group has been introduced is preferably used as the interposed resin.

[0380] The shape of the secondary battery using the above-mentioned electrolyte solution is arbitrary, and examples of the shape include a cylindrical shape, a square shape, a laminated shape, a coin shape, a large shape, etc. The shapes and configurations of the positive electrode, the negative electrode, and the separator can be changed according to the shape of each battery.

[0381] The present disclosure also provides a mixture for an electrolyte layer, comprising the above-mentioned TFE-based polymer composition of the present disclosure or the binder of the present disclosure and a solid electrolyte. By using the mixture for an electrolyte layer of the present disclosure, a solid electrolyte with suppressed deterioration can be obtained. In addition, the strength of the mixture sheet can be improved. In addition, even if the amount of the binder is small, the solid electrolyte can be held, so that more solid electrolyte can be added.

[0382] The solid electrolyte may be a sulfide-based solid electrolyte or an oxide-based solid electrolyte. In particular, when a sulfide-based solid electrolyte is used, it has the advantage of being flexible.

[0383] The sulfide-based solid electrolyte is not particularly limited, and examples thereof include Li2S-P2S5, Li2S-P2S3, Li2S-P2S3-P2S5, Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, LiI-Li2S-SiS2-P2S5, Li2S-SiS2-Li4SiO4, Li2S-SiS2-Li3PO4, Li3PS4-Li4GeS4, Li 3.4 P 0.6 S 0.4 S4, Li 3.25 P 0.25 Ge 0.76 S4, Li 4-x Ge 1-x P x S4(X=0.6~0.8), Li 4+y Ge 1-y Ga y S4(y=0.2~0.3), LiPSCl, LiCl, Li 7-x-2y P.S. 6-x-y Cl x (0.8≦x≦1.7, 0 <y≦-0.25x+0.5)、Li 10 SnP2S 12 Any one selected from the above, or a mixture of two or more of them, can be used.

[0384] The sulfide-based solid electrolyte preferably contains lithium. The sulfide-based solid electrolyte containing lithium is used in a solid-state battery that uses lithium ions as a carrier, and is particularly preferred in terms of electrochemical devices having a high energy density.

[0385] The oxide-based solid electrolyte is preferably a compound that contains an oxygen atom (O), has the ionic conductivity of a metal belonging to Group 1 or 2 of the periodic table, and has electronic insulation properties.

[0386] Specific examples of compounds include Li xa La ya TiO3 [xa=0.3~0.7, ya=0.3~0.7] (LLT), Li xb La yb Zr zb M bb mb O nb (M bb is at least one of the elements Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, In, and Sn, where xb satisfies 5≦xb≦10, yb satisfies 1≦yb≦4, zb satisfies 1≦zb≦4, mb satisfies 0≦mb≦2, and nb satisfies 5≦nb≦20. ), Li xc B yc M cc zc O nc (M cc is at least one element selected from C, S, Al, Si, Ga, Ge, In, and Sn, where xc satisfies 0≦xc≦5, yc satisfies 0≦yc≦1, zc satisfies 0≦zc≦1, and nc satisfies 0≦nc≦6. ), Li xd (Al,Ga) yd (Ti,Ge) zd S ad P md O nd (where 1≦xd≦3, 0≦yd≦2, 0≦zd≦2, 0≦ad≦2, 1≦md≦7, 3≦nd≦15), Li (3-2xe) M ee xe D ee O(xe is a number between 0 and 0.1, and M eerepresents a divalent metal atom. ee represents a halogen atom or a combination of two or more halogen atoms. xf S yf O zf (1≦xf≦5, 0 <yf≦3、1≦zf≦10)、Li xg S yg O zg (1≦xg≦3, 0 <yg≦2、1≦zg≦10)、Li3BO3-Li2SO4、Li2O-B2O3-P2O5、Li2O-SiO2、Li6BaLa2Ta2O 12 , LiPO (4-3 / 2w) N w (w is w<1), Li with LISICON (Lithium super ionic conductor) type crystal structure 3.5 Zinc 0.25 GeO4, La with perovskite crystal structure 0.51 Li 0.34 TiO 2.94 , La 0.55 Li 0.35 TiO3, LiTi2P3O with NASICON (sodium super ionic conductor) type crystal structure 12 , Li 1+xh+yh (Al,Ga) xh (Ti,Ge) 2-xh S yh P 3-yh O 12 (where 0≦xh≦1, 0≦yh≦1), Li7La3Zr2O with a garnet-type crystal structure 12 (LLZ), etc. Ceramic materials in which elements have been substituted for LLZ are also known. For example, Li 6.24 La3Zr2Al 0.24 O 11.98 , Li 6.25 Al 0.25 La3Zr2O 12 and Li substituted with Ta 6.6 La3Zr 1.6 Ta 0.4 O 12 , Li substituted with Nb 6.75 La3Zr 1.75 Nb 0.25 O12 Other examples include LLZ-based ceramic materials in which at least one of Mg (magnesium) and A (A is at least one element selected from the group consisting of Ca (calcium), Sr (strontium), and Ba (barium)) is substituted for LLZ. Phosphorus compounds containing Li, P, and O are also desirable. For example, lithium phosphate (Li3PO4), LiPON, LiPOD, in which part of the oxygen in lithium phosphate is substituted with nitrogen, etc. 1 (D 1 is at least one selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Ag, Ta, W, Pt, Au, etc. In addition, LiA 1 ON(A 1 is at least one selected from Si, B, Ge, Al, C, Ga, etc. Specific examples include Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2 and Li2O-Al2O3-SiO2-P2O5-TiO2.

[0387] The oxide-based solid electrolyte preferably contains lithium. The oxide-based solid electrolyte containing lithium is used in a solid-state battery that uses lithium ions as a carrier, and is particularly preferred in terms of electrochemical devices having a high energy density.

[0388] The oxide-based solid electrolyte is preferably an oxide having a crystalline structure. Oxides having a crystalline structure are particularly preferred in terms of good Li-ion conductivity. Examples of oxides having a crystalline structure include perovskite-type (La 0.51 Li 0.34 TiO 2.94 etc.), NASICON type (Li 1.3 Al 0.3 Ti 1.7 (PO4)3), garnet type (Li7La3Zr2O 12 (LLZ), etc. Among these, the NASICON type is preferred.

[0389] The volume average particle diameter of the oxide-based solid electrolyte is not particularly limited, but is preferably 0.01 μm or more, and more preferably 0.03 μm or more. The upper limit is preferably 100 μm or less, and more preferably 50 μm or less. The average particle diameter of the oxide-based solid electrolyte particles is measured by the following procedure. The oxide-based solid electrolyte particles are diluted and adjusted to a 1 mass% dispersion in a 20 ml sample bottle using water (heptane in the case of a substance unstable in water). The diluted dispersion sample is irradiated with 1 kHz ultrasonic waves for 10 minutes and used for testing immediately thereafter. Using this dispersion sample, data is taken 50 times using a laser diffraction / scattering type particle size distribution measuring device LA-920 (manufactured by HORIBA) at a temperature of 25°C using a measurement quartz cell to obtain the volume average particle diameter. For other detailed conditions, etc., refer to the description of JISZ8828:2013 "Particle size analysis - dynamic light scattering method" as necessary. Five samples are prepared for each level and the average value is adopted.

[0390] The present disclosure also provides a solid-state secondary battery comprising the above-mentioned solid electrolyte. The solid-state secondary battery is preferably an all-solid-state secondary battery. The solid-state secondary battery is preferably a lithium-ion battery, and is also preferably a sulfide-based solid-state secondary battery. The solid secondary battery preferably includes a positive electrode, a negative electrode, and a solid electrolyte layer interposed between the positive electrode and the negative electrode.

[0391] The solid secondary battery may include a separator between the positive electrode and the negative electrode. Examples of the separator include porous membranes such as polyethylene and polypropylene, and nonwoven fabrics such as nonwoven fabrics made of resins such as polypropylene and nonwoven fabrics made of glass fibers.

[0392] The solid secondary battery may further include a battery case. The shape of the battery case is not particularly limited as long as it can accommodate the above-mentioned positive electrode, negative electrode, solid electrolyte layer, etc., but specific examples include a cylindrical type, a square type, a coin type, a laminate type, etc.

[0393] The solid secondary battery can be produced, for example, by stacking a positive electrode, a solid electrolyte layer sheet, and a negative electrode in this order and pressing them.

[0394] Although the embodiments have been described above, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the claims. EXAMPLES

[0395] The present disclosure will now be described in more detail with reference to examples, but the present disclosure is not limited to these examples.

[0396] Various physical properties were measured by the following methods.

[0397] <Oxygen concentration in reactor> The gas coming out of the exhaust gas line of the reactor under N2 flow was measured and analyzed using a low-concentration oxygen analyzer (product name "PS-820-L", manufactured by Iijima Electronics Co., Ltd.) to determine the oxygen concentration during the reaction.

[0398] <Polymer (polymer D, K, etc.) concentration> Approximately 1 g of the aqueous polymer solution was dried in a vacuum dryer at 60°C for 60 minutes, the mass of the heating residue was measured, and the ratio of the mass of the heating residue to the mass (1 g) of the aqueous polymer solution was expressed as a percentage.

[0399] <Method of measuring weight average molecular weight (Mw) and number average molecular weight (Mn) of polymer D> The Mw and Mn of polymer D were measured by gel permeation chromatography (GPC) using a GPC HLC-8020 manufactured by Tosoh Corporation and Shodex columns (one GPC KF-801, one GPC KF-802, and two GPC KF-806M connected in series) with tetrahydrofuran (THF) as a solvent at a flow rate of 1 ml / min, and the molecular weight was calculated using monodisperse polystyrene as a standard.

[0400] <Method of measuring weight average molecular weight (Mw), number average molecular weight (Mn) and content of fraction having molecular weight of 3000 or less of polymer L> The Mw and Mn of the polymer L were determined by gel permeation chromatography (GPC) using an Agilent Technologies 1260 Infinity II column (TSKgel G3000PW) and a Tosoh column (TSKgel G3000PW). XL and TSG gel GMPW XL A mixed solvent of Tris buffer and acetonitrile (Tris buffer:acetonitrile = 8:2 (v / v)) was run at a flow rate of 0.5 ml / min for measurement, and the molecular weight was calculated using monodisperse polyethylene oxide (PEO) and polyethylene glycol (PEG) as standards.

[0401] <Method for measuring the content of dimers and trimers of monomers (monomers D and K) in polymers (polymers D, K, etc.)> (1) Extraction from aqueous solution The solid content of the aqueous solution of the polymer was measured, and an amount of the aqueous solution equivalent to 0.2 g of the solid content of the polymer was weighed. Then, the aqueous solution was combined with the water contained in the aqueous solution, and water and methanol were added so that the volume ratio of water to methanol was 50 / 50 (volume %) to obtain a mixed solution containing the polymer, water, and methanol. Then, the obtained mixed solution was centrifuged at 4000 rpm for 1 hour to obtain a supernatant containing the polymer, and the obtained supernatant was filtered using an ultrafiltration disk (molecular weight cutoff 3000 Da) and collected as an extract. The extract was analyzed using a liquid chromatograph mass spectrometer (Waters, LC-MS ACQUITY UPLC / TQD) to obtain a chromatogram of the extract. The contents of dimer and trimer monomers contained in the extract were determined by converting the integral values ​​of the peaks derived from dimer and trimer monomers appearing in the chromatogram of the extract into the contents of dimer and trimer monomers using a calibration curve.

[0402] (2) Monomer calibration curve Five levels of methanol standard solutions of monomers with known contents ranging from 1 ng / mL to 100 ng / mL were prepared, and measurements were performed using a liquid chromatograph mass spectrometer (Waters, LC-MS ACQUITY UPLC / TQD). The relationship between the content of each monomer and the peak integral value for that content was plotted, and a calibration curve (first-order approximation) for each monomer was created. Next, the calibration curves (first-order approximation) for each monomer were used to create calibration curves for the dimer and trimer of each monomer.

[0403] Measurement equipment configuration and LC-MS measurement conditions [Table 1]

[0404] The limit of quantification for this measurement configuration is 1 ng / mL.

[0405] <DLS measurement of polymers (polymers D, K, etc.)> In the dynamic light scattering method, a polymer dispersion with a solid content adjusted to about 1.0% by mass was prepared and measured at 25°C with an ELSZ-1000S (Otsuka Electronics Co., Ltd.) for an accumulated measurement of 70 times. The refractive index of the solvent (water) was 1.3328, and the viscosity of the solvent (water) was 0.8878 mPa s.

[0406] <Polymer solids concentration> 1 g of the TFE-based polymer aqueous dispersion is dried in a blower dryer at 150° C. for 60 minutes, and the ratio of the mass of the heating residue to the mass (1 g) of the aqueous dispersion is expressed as a percentage.

[0407] <Average primary particle diameter> The average primary particle size was measured by dynamic light scattering. In the dynamic light scattering method, a TFE-based polymer aqueous dispersion with a solid content concentration adjusted to approximately 1.0 mass% was prepared, and measurements were taken at 25°C and 70 times cumulatively using an ELSZ-1000S (Otsuka Electronics Co., Ltd.). The refractive index of the solvent (water) was 1.3328, and the viscosity of the solvent (water) was 0.8878 mPa s.

[0408] <Moisture content> Measure the mass of about 20 g of the TFE-based polymer composition before and after heating at 150 °C for 2 hours, and calculate according to the following formula. Take the sample three times, calculate each time, then find the average, and adopt the average value. Moisture content (mass%) = [(mass of TFE-based polymer composition before heating (g)) - (mass of TFE-based polymer composition after heating (g))] / (mass of TFE-based polymer composition before heating (g)) × 100

[0409] <Standard specific gravity (SSG)> Using the sample molded in accordance with ASTM D4895 89, measure by the water displacement method in accordance with ASTM D 792.

[0410] <Content of modified monomer> The HFP content was determined by preparing a thin film disk by press molding the TFE-based polymer composition and multiplying the ratio of the absorbance at 982 cm -1 to the absorbance at 935 cm -1 in the infrared absorbance measured for the thin film disk by 0.3.

[0411] <Endothermic peak temperature> The endothermic peak temperature was measured using a DSC (differential scanning calorimeter) by accurately weighing about 10 mg of the powder of the TFE-based polymer without a heating history at a temperature of 300 °C or higher. The endothermic peak temperature was taken as the temperature corresponding to the minimum value in the melting heat curve obtained by raising the temperature under the condition of 10 °C / min.

[0412] <Content of polymer (polymer D, L) in the TFE-based polymer composition> The content of polymer D contained in the TFE-based polymer composition was determined from the spectrum obtained by solid 19 F-MAS NMR measurement.

[0413] <Extrusion pressure> The extrusion pressure was determined by the following method in accordance with the method described in JP-A-2002-201217. 21.7 g of lubricant (trade name: Isopar H (registered trademark), manufactured by Exxon Corp.) was added to 100 g of the TFE-based polymer composition, and mixed in a glass bottle at room temperature for 3 minutes. The glass bottle was then left at room temperature (25°C) for at least 1 hour before extrusion to obtain a lubricated resin. The lubricated resin was paste-extruded at room temperature through an orifice (diameter 2.5 mm, land length 11 mm, introduction angle 30°) at a reduction ratio of 100:1 to obtain a uniform bead (beading; extrusion molded body). The extrusion speed, i.e., the ram speed, was 20 inches / min (51 cm / min). The load when the extrusion load reached equilibrium in the paste extrusion was measured, and the extrusion pressure was calculated by dividing the load by the cross-sectional area of ​​the cylinder used for the paste extrusion.

[0414] <Stretching test> The stretching test was carried out in accordance with the method described in JP-A-2002-201217, as described below. The bead obtained by the above paste extrusion was heated at 230°C for 30 minutes to remove the lubricant from the bead. The bead (extrudate) was then cut to the appropriate length, clamped at each end with a clamp distance of 1.5 inches (38 mm) apart, and heated to 300°C in an air circulating oven. The clamps were then separated at a desired speed (stretch rate) until a separation distance corresponding to the desired stretch (total stretch) was achieved, and a stretch test (stretch test) was performed. The stretch method essentially followed the method disclosed in U.S. Pat. No. 4,576,869, except for the extrusion speed (51 cm / min instead of 84 cm / min). "Stretch" is the increase in length due to stretching, usually expressed as a percentage of the original length. In the stretch method, the stretch rate was 1000% / sec, and the total stretch was 2400%. A specimen that did not break during stretching in the above stretch test was considered to be stretchable.

[0415] <Fluorine-containing compound content> 1 g of each TFE-based polymer composition was weighed, 10 g (12.6 ml) of methanol was added, and ultrasonic treatment was performed for 60 minutes to obtain an extract. The obtained extract was measured by LC / MS / MS. The fluorine-containing compounds in the extract were measured using a liquid chromatograph mass spectrometer (Waters, LC-MS ACQUITY UPLC / TQD). The measurement equipment configuration and LC-MS measurement conditions are shown in Table 2. Using an aqueous solution of a fluorine-containing compound with a known concentration, aqueous solutions with five or more levels of content were prepared, and LC / MS analysis was performed on the aqueous solutions with each content. The relationship between the content and the area area relative to the content was plotted to draw a calibration curve. Using the above calibration curve, the area area of ​​the LC / MS chromatogram of the fluorine-containing compound in the extract was converted to the content of the fluorine-containing compound. The lower limit of quantification in this measurement method is 10 ppb by mass.

[0416] [Table 2]

[0417] Preparation Example 1 A reactor was charged with 220 g of monomer D represented by CH2=CF(CF2OCFCF3COOH) and 513 g of water, and further added with 0.5 mol % of ammonium persulfate (APS) based on monomer D. The mixture was heated and stirred at 60°C for 24 hours under a nitrogen atmosphere to obtain an aqueous solution of polymer D D-1 containing polymer D, which is a homopolymer of CH2=CF(CF2OCFCF3COOH). The resulting aqueous solution of polymer D D-1 was subjected to GPC analysis, and as a result, polymer D had Mw of 180,000, Mn of 86,000, and the content of dimers and trimers was 2.0% by mass relative to polymer D.

[0418] Water was added to the obtained polymer D aqueous solution D-1 to adjust the concentration of polymer D to 5.0% by mass, and then ultrafiltration was performed by contacting the solution with an ultrafiltration membrane (molecular weight cutoff 50,000 Da, made of polyethylene) at 30 ° C. and a water pressure of 0.1 MPa. Ultrafiltration was continued while appropriately injecting water until the filtrate was finally dissolved in an amount of water 7 times the amount of the aqueous solution, to obtain a polymer D aqueous solution D-2. As a result of GPC analysis of the obtained polymer D aqueous solution D-2, the polymer D had Mw 180,000, Mn 140,000, and the content of dimers and trimers was less than 1 ppm relative to the polymer D. The concentration of the obtained polymer D aqueous solution D-2 was 5.0% by mass. When the polymer D aqueous solution D-2 was analyzed by DLS, the particle size could not be measured. The content of ionic groups in the polymer D was 3.91 meq / g, the fluorine substitution rate was 80%, and the ion exchange rate was 4.

[0419] Manufacturing Example 1 In a 6L stainless steel reactor equipped with a stirrer, 3457g of deionized water, 180g of paraffin wax, 107.4g of polymer D aqueous solution D-2, 1.8g of 0.1% by mass Triton (registered trademark) X-100 (trade name, manufactured by Dow Chemical Company) aqueous solution, and 1.1g of 1.0% by mass isopropanol aqueous solution were placed. Ammonia water was added to adjust the pH to 9.1. The contents of the reactor were then heated to 70°C while being aspirated and purged with TFE at the same time to remove oxygen from the reactor, and the contents were stirred. 2.4g of HFP was added to the reactor, and TFE was added until the pressure reached 0.73MPaG. 17.9mg of ammonium persulfate (APS) initiator dissolved in 20g of deionized water was injected into the reactor, and the pressure of the reactor was set to 0.83MPaG. After the injection of the initiator, a decrease in pressure occurred and the initiation of polymerization was observed. TFE was added to the reactor to keep the pressure constant at 0.78 MPaG. When the amount of TFE consumed in the reaction reached about 180 g, the supply of TFE and stirring were stopped. The gas in the reactor was then slowly released until the pressure in the reactor reached 0.02 MPaG. TFE was then supplied until the pressure in the reactor reached 0.78 MPaG, and stirring was started again to continue the reaction. When the amount of TFE consumed in the reaction reached about 540 g, 14.3 mg of hydroquinone dissolved in 20 g of deionized water was injected into the reactor, and the reaction was continued. When the amount of TFE consumed in the reaction reached about 1200 g, the supply of TFE was stopped, stirring was stopped, and the reaction was terminated. The pressure in the reactor was then vented to normal pressure, and the contents were removed from the reactor and cooled. The supernatant paraffin wax was removed from the TFE-based polymer aqueous dispersion. The resulting TFE-based polymer aqueous dispersion had a solid concentration of 24.4% by mass and an average primary particle size of 261 nm.

[0420] Preparation example 1 The TFE-based polymer aqueous dispersion obtained in Production Example 1 was diluted with deionized water to a solid content of 13% by mass, and the mixture was stirred vigorously in a container equipped with a stirrer to solidify, and then filtered to obtain a wet powder. The water content of the wet powder was about 45% by mass. The obtained wet powder was placed on a stainless steel mesh tray (amount placed: 2.0 g / cm2 ) The mesh tray was heat-treated in a hot air circulating electric furnace at 210° C. After 18 hours, the mesh tray was taken out and cooled in air, and then a TFE-based polymer composition A was obtained. The obtained TFE-based polymer composition A had a water content of 0.002% by mass, a standard specific gravity of 2.176, an endothermic peak temperature of 342° C., an HFP content of 0.094% by mass, and a polymer D content of 0.46% by mass. The extrusion pressure was 24.4 MPa, and stretching was possible.

[0421] Example 2 A TFE-based polymer composition X was obtained in the same manner as in Preparation Example 1, except that the mesh tray was replaced with a flat tray (a tray with no air permeability at the bottom and sides) and the heat treatment time was changed to 5 hours. The water content of the resulting TFE polymer composition X was 0.072% by mass.

[0422] Preparation example 3 The TFE-based polymer aqueous dispersion obtained in Production Example 1 was diluted with deionized water to a solid content of 13% by mass, and the polymer D aqueous solution D-2 was added so that the polymer D was contained in an amount equivalent to 1.0% by mass relative to the TFE-based polymer solid content, and the mixture was stirred vigorously in a container equipped with a stirrer to solidify, and then filtered to separate the water. The moisture content of the wet powder was about 45% by mass. The obtained wet powder was placed on a stainless steel mesh tray (amount placed: 2.0 g / cm 2 ) The mesh tray was heat-treated in a hot air circulating electric furnace at 210° C. After 18 hours, the mesh tray was taken out and cooled in air, and then a TFE-based polymer composition B was obtained. The resulting TFE-based polymer composition B had a water content of 0.002% by mass and a polymer D content of 1.00% by mass.

[0423] Preparation Example 4 The TFE-based polymer aqueous dispersion obtained in Production Example 1 was diluted with deionized water to a solids concentration of 13% by mass, and the dilution was vigorously stirred in a vessel equipped with a stirrer to cause solidification, and then filtered to separate the water. The filtered polymer was washed with methanol in an amount equivalent to 4 times the amount of the TFE-based polymer solid content, and then washed with water to obtain a wet powder having a water content of about 45% by mass. The obtained wet powder was placed on a stainless steel mesh tray (amount placed: 2.0 g / cm 2 ) The mesh tray was heat-treated in a hot air circulating electric furnace at 210° C. After 18 hours, the mesh tray was taken out and cooled in air, and then a TFE-based polymer composition C was obtained. The resulting TFE-based polymer composition C had a water content of 0.002% by mass and a polymer D content of 0.10% by mass.

[0424] Preparation Example 2 170 g of sodium 1,1,2,2-tetrafluoro-2-((1,2,2-trifluorovinyl)oxy)ethane-1-sulfonate (monomer K), 340 g of water, and ammonium persulfate (APS) in an amount equivalent to 2.0 mol% relative to the amount of monomer K were added to a reactor, and the mixture was stirred at 40°C for 72 hours under N2 flow to obtain an aqueous solution of polymer K K-1 containing polymer K, which is a homopolymer of monomer K. The oxygen concentration in the reactor was in the range of 15 ppm by volume to 800 ppm by volume.

[0425] Water was added to the obtained polymer K aqueous solution K-1 to adjust the concentration of polymer K to 3.8% by mass, and then ultrafiltration was performed by contacting the solution with an ultrafiltration filter (molecular weight cutoff 6000 Da, made of polysulfone) at 25°C and a water pressure of 0.1 MPa. Ultrafiltration was continued while appropriately injecting water until the filtrate was finally dissolved in an amount of water 4 times the amount of the aqueous solution, to obtain an aqueous solution of polymer K K-2. The concentration of the obtained aqueous solution was 1.6% by mass.

[0426] 300 ml of Amberlite (IR120B(H)-HG) was measured into a container, washed with water until no color remained, then 500 ml of 1M-HCl was added and stirred at room temperature for 1 hour. Amberlite was packed into a column with a stopcock, and water was poured into the column until the acidity of the waste liquid became neutral. The obtained polymer K aqueous solution K-2 was poured into the column with a stopcock, and dripping was started. After dripping was completed, water was poured into the column until the dripping liquid became neutral, and polymer L aqueous solution L-1 containing polymer L of 1,1,2,2-tetrafluoro-2-((1,2,2-trifluorovinyl)oxy)ethane-1-sulfonic acid (monomer L) was obtained. The concentration of the obtained aqueous solution was 1.5% by mass.

[0427] The polymer L aqueous solution L-1 was analyzed. The weight average molecular weight (Mw) of the polymer L was 1.0×10 4 , number average molecular weight (Mn) is 0.8×10 4 It was.

[0428] The content of dimers and trimers of monomer L in the aqueous solution of polymer L-1 was 0.1% by mass or less relative to polymer L. The content of fractions having a molecular weight of 3000 or less in the aqueous solution of polymer L-1 was 0.5% or less. When the aqueous solution of polymer L-1 was subjected to DLS analysis, the particle size could not be measured. The content of ionic groups in polymer L was 3.60 meq / g, the fluorine substitution rate was 100%, and the ion exchange rate was 4.

[0429] Manufacturing Example 2 In a 6L SUS reactor equipped with a stirrer, 3087g of deionized water, 104g of paraffin wax, 477g of polymer L aqueous solution L-1, and 3.58g of 0.1% by mass aqueous isopropanol solution were placed. Ammonia water was then added to adjust the pH to 9.0, and the reactor contents were heated to 70°C while being aspirated and simultaneously purged with TFE to remove oxygen from the reactor, and the contents were stirred. After adding 5.8g of HFP to the reactor, TFE was added until the pressure reached 0.73MPaG. 17.9mg of ammonium persulfate (APS) initiator dissolved in 20g of deionized water was injected into the reactor, and the reactor pressure was set to 0.83MPaG. After the injection of the initiator, a pressure drop occurred and the start of polymerization was observed. TFE was added to the reactor to keep the pressure constant at 0.78MPaG. When the amount of TFE consumed in the reaction reached about 180g, the supply of TFE and stirring were stopped.

[0430] The gas in the reactor was then slowly released until the reactor pressure reached 0.02 MPaG. TFE was then fed until the reactor pressure reached 0.78 MPaG, and stirring was started again to continue the reaction. When the amount of TFE consumed in the reaction reached about 540 g, 14.3 mg of hydroquinone dissolved in 20 g of deionized water was injected into the reactor, and the reaction was continued. When the amount of TFE consumed in the reaction reached about 1250 g, the feeding of TFE was stopped, stirring was stopped, and the reaction was terminated. The reactor was then vented until the pressure in the reactor reached normal pressure, and the contents were removed from the reactor and cooled. The supernatant paraffin wax was removed from the TFE-based polymer aqueous dispersion.

[0431] The solid content of the resulting TFE-based polymer aqueous dispersion was 25.5% by mass, and the average primary particle size was 182 nm.

[0432] Preparation example 5 The TFE-based polymer aqueous dispersion obtained in Production Example 2 was diluted with deionized water to a solid content of 13% by mass, and the mixture was vigorously stirred in a container equipped with a stirrer to solidify, and then filtered to obtain a wet powder. The water content of the wet powder was about 45% by mass. The obtained wet powder was placed on a stainless steel mesh tray (amount placed: 2.0 g / cm 2 ) The mesh tray was heat-treated in a hot air circulating electric furnace at 240° C. After 18 hours, the mesh tray was taken out and cooled in air, and then a TFE-based polymer composition D was obtained. The resulting TFE-based polymer composition D had a water content of 0.002% by mass, a standard specific gravity of 2.165, an endothermic peak temperature of 344° C., an HFP content of 0.294% by mass, and a polymer L content of 0.58% by mass. The extrusion pressure was 17.9 MPa, and stretching was possible.

[0433] The fluorine-containing compound represented by the following formula was not detected from the TFE polymer compositions obtained in Preparation Examples 1 to 5. That is, the concentration was less than 10 ppb by mass. F(CF2)7COOH, F(CF2)5COOH, H(CF2)6COOH, H(CF2)7COOH, CF3O(CF2)3OCHFCF2COOH, C3F7OCF(CF3)CF2OCF(CF3)COOH, CF3CF2CF2OCF(CF3)COOH, CF3CF2OCF2CF2OCF2COOH, C2F5OCF(CF3)CF2OCF(CF3)COOH, CF3OCF(CF3)CF2OCF(CF3)COOH, CF2ClCF2CF2OCF(CF3)CF2OCF2COOH, CF2ClCF2CF2OCF2CF(CF3)OCF2COOH, CF2ClCF(CF3)OCF(CF3)CF2OCF2COOH, CF2ClCF(CF3)OCF2CF(CF3)OCF2COOH, and [ka] (In the formula, M is H.)

[0434] Using each of the TFE-based polymer compositions obtained above, a positive electrode mixture sheet, an electrode, and a lithium ion secondary battery were produced by the following method, and evaluated.

[0435] Evaluation of electrolyte-containing batteries The mixture sheets of Examples 1 to 4 and Comparative Example 1 were prepared, and the mixture sheets and batteries were evaluated according to the following procedures. <Preparation of positive electrode mixture sheet> The active material and conductive additive were weighed, and the materials were put into a V-type mixer and mixed at 37 rpm for 10 minutes to obtain a mixture of the active material and conductive additive. Then, the weighed binder (TFE-based polymer composition) was put into the mixture and cooled sufficiently in a thermostatic chamber at 5°C. The mixture of the active material, conductive additive, and binder was put into a Henschel mixer and homogenized by processing at 1000 rpm for 3 minutes. Thereafter, the mixture was sufficiently heated in a thermostatic bath at 50° C., and then treated in a Henschel mixer at 1500 rpm for 10 minutes to promote fibrillation, thereby obtaining an electrode mixture. The electrode mixture was placed between parallel metal rolls (temperature: 80°C, rotation speed: 1 m / min) and rolled to obtain an electrode mixture sheet. The rolled sheet obtained was again folded in half to be roughly crushed, and the electrode mixture was placed between metal rolls (temperature: 80°C, rotation speed: 1 m / min) and rolled to obtain a stronger electrode mixture sheet. Thereafter, the electrode mixture sheet was placed in a roll press machine and the gap was adjusted to a final thickness of 90 μm. Table 3 shows the material types and compositions.

[0436] [Table 3] SuperP Li: Carbon black manufactured by Imerys

[0437] <Measurement of the strength of the positive electrode mixture sheet> The positive electrode mixture sheet was cut out to prepare a rectangular test piece with a width of 4 mm. A tensile tester (AGS-100NX manufactured by Shimadzu Corporation) was used to measure at a speed of 100 mm / min. The chuck distance was 30 mm. Displacement was applied until breakage, and the maximum stress of the measured results was taken as the strength of each sample. Comparative Example 1 was set at 100 for comparison. Samples with high tensile strength and good electrode strength were ranked from A to E. A: 230 or more B:180~229 C:120~179 D:105~119 E: Less than 105 The results are shown in Table 4.

[0438] <Flexibility evaluation of positive electrode mixture sheet (bending test)> The prepared positive electrode mixture sheet was cut into a width of 4 cm and a length of 10 cm to prepare test pieces. Next, these test pieces were wrapped around a Φ10 mm round bar, and the test pieces were visually inspected to confirm the presence or absence of damage such as scratches or cracks. If no damage was observed, a test was performed using a thinner Φ5 mm round bar to confirm damage. Again, if no damage was observed, a test was performed using a thinner Φ2 mm round bar to confirm damage. The results were classified into A to D. A: No damage with Φ2mm rod B: Φ2mm rod damaged C: Φ5mm rod damaged D: Φ10mm rod damaged The results are shown in Table 4.

[0439] <Preparation of positive electrode> The above positive electrode mixture sheet was adhered to 20 μm aluminum foil as follows. The adhesive used was a slurry of polyvinylidene fluoride (PVDF) dissolved in N-methylpyrrolidone (NMP) and carbon black dispersed in a ratio of 80:20. The adhesive was applied to aluminum foil and dried on a hot plate at 120°C for 15 minutes to form a current collector with an adhesive layer. Thereafter, the positive electrode mixture sheet was placed on a collector with an adhesive layer, and the positive electrode mixture sheet and the collector were bonded together using a roll press machine heated to 100°C. The sheet was then cut to the desired size and tabbed to form a positive electrode.

[0440] <Preparation of negative electrode> 98 parts by mass of carbonaceous material (graphite) was mixed with 1 part by mass of aqueous dispersion of sodium carboxymethylcellulose (concentration of sodium carboxymethylcellulose: 1% by mass) and 1 part by mass of aqueous dispersion of styrene-butadiene rubber (concentration of styrene-butadiene rubber: 50% by mass) as a thickener and binder, and the mixture was mixed with a disperser to form a slurry. The obtained slurry was applied to a copper foil having a thickness of 10 μm, dried, and rolled with a press machine, cut to the desired size, and tabbed to form a negative electrode.

[0441] <Preparation of electrolyte> As an organic solvent, a mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) (EC:EMC=30:70 (volume ratio)) was weighed into a sample bottle, and fluoroethylene carbonate (FEC) and vinylene carbonate (VC) were dissolved in the sample bottle at 1 mass% each to prepare a mixed solution. A nonaqueous electrolyte was obtained by mixing LiPF6 salt into the mixed solution at 23°C so that the concentration in the electrolyte was 1.1 mol / L.

[0442] <Preparation of aluminum laminated cell> The positive electrode was placed opposite to the negative electrode via a 20 μm-thick microporous polyethylene film (separator), and the nonaqueous electrolyte obtained above was poured into the positive electrode. After the nonaqueous electrolyte had sufficiently permeated the separator and the like, the positive electrode was sealed, precharged, and aged to prepare a lithium ion secondary battery.

[0443] <Evaluation of storage characteristics (remaining capacity rate, amount of gas generated)> The lithium ion secondary battery produced above was charged at 25°C with a constant current and constant voltage (hereinafter referred to as CC / CV charging) to 4.3 V at a current equivalent to 0.33 C (0.1 C cut), and then discharged to 3 V at a constant current of 0.33 C. This was counted as one cycle, and the initial discharge capacity was calculated from the discharge capacity at the third cycle. The battery after the evaluation of the initial discharge capacity was again CC / CV charged (0.1C cut) at 25°C to 4.3V, and the volume of the battery was determined by Archimedes' method. After the volume of the battery was determined, it was stored at high temperature at 60°C for 30 days. After the high temperature storage, the battery was sufficiently cooled and then the volume of the battery was determined at 25°C, and the amount of gas generated was calculated from the difference in the volume of the battery before and after the storage test. The amount of gas generated in Comparative Example 1 was set to 100 for comparison. After determining the amount of gas generated, the battery was discharged at 0.33 C to 3 V at 25° C., and the remaining capacity was determined. The ratio of the remaining capacity after high-temperature storage to the initial discharge capacity was calculated and this was taken as the remaining capacity rate (%). (Residual capacity) / (Initial discharge capacity)×100=Remaining capacity rate (%) The results are shown in Table 4.

[0444] [Table 4]

[0445] Evaluation of electrode mixture sheets for solid-state batteries The mixture sheets of Examples 5 to 11 and Comparative Examples 2 to 5 were produced and evaluated according to the following procedures. <Preparation of positive electrode mixture sheet> The active material and conductive assistant were weighed, and the materials were put into a V-type mixer and mixed at 37 rpm for 10 minutes to obtain a mixture of the active material and conductive assistant. Then, weighed binder (TFE-based polymer composition) and solid electrolyte were put into the mixture, and it was cooled sufficiently in a thermostatic bath at 5°C. The mixture of the active material, conductive assistant, binder, and solid electrolyte was put into a Henschel mixer, and the mixture was homogenized by processing at 300 rpm for 2 minutes. Thereafter, the mixture was sufficiently heated in a thermostatic bath at 40° C., and then treated in a Henschel mixer at 1000 rpm for 3 minutes to promote fibrillation, thereby obtaining an electrode mixture. The electrode mixture was placed between parallel metal rolls (temperature: 80°C, rotation speed: 1 m / min) and rolled to obtain an electrode mixture sheet. The rolled sheet obtained was again folded in half to be roughly crushed, and the electrode mixture was placed between metal rolls (temperature: 80°C, rotation speed: 1 m / min) and rolled to obtain a stronger electrode mixture sheet. Thereafter, the electrode mixture sheet was placed in a roll press machine and the gap was adjusted to a final thickness of 150 μm. Table 5 shows the material types and compositions.

[0446] [Table 5] denka Li-400: Carbon black manufactured by Denka

[0447] <Measurement of the strength of the positive electrode mixture sheet> The positive electrode mixture sheet was cut out to prepare a strip-shaped test piece with a width of 4 mm. A tensile tester (AGS-100NX manufactured by Shimadzu Corporation) was used to measure at 100 mm / min. The chuck distance was 30 mm. Displacement was applied until breakage, and the maximum stress of the measurement result was taken as the strength of each sample. Comparative Example 2 was set to 100 and compared with Examples 5 to 8, Comparative Example 3 was set to 100 and compared with Example 9, Comparative Example 4 was set to 100 and compared with Example 10, and Comparative Example 5 was set to 100 and compared with Example 11. The samples were ranked from A to E in order of high tensile strength and good electrode strength. A: 230 or more B:180~229 C:120~179 D:105~119 E: Less than 105 The results are shown in Table 6.

[0448] <Flexibility evaluation of positive electrode mixture sheet (bending test)> The prepared electrode mixture sheet was cut into a width of 4 cm and a length of 10 cm to prepare test pieces. Next, these test pieces were wrapped around a Φ10 mm round bar, and the test pieces were visually inspected to confirm the presence or absence of damage such as scratches or cracks. If no damage was observed, a test was performed using a thinner Φ5 mm round bar to confirm damage. Again, if no damage was observed, a test was performed using a thinner Φ2 mm round bar to confirm damage. The results were classified into A to D. A: No damage with Φ2mm rod B: Φ2mm rod damaged C: Φ5mm rod damaged D: Φ10mm rod damaged The results are shown in Table 6.

[0449] [Table 6]

[0450] Solid electrolyte mixture sheet evaluation The mixture sheets of Examples 12 to 18 and Comparative Examples 6 to 9 were produced and evaluated according to the following procedures. <Preparation of solid electrolyte mixture sheet> The weighed binder (TFE-based polymer composition) was sufficiently cooled in a thermostatic bath at 5° C., and then charged into a Henschel mixer and pulverized at 300 rpm for 2 minutes. The crushed binder and solid electrolyte were each weighed and thoroughly cooled in a thermostatic bath at 5° C. The mixture was then placed in a Henschel mixer and homogenized by processing at 300 rpm for 1 minute. Thereafter, the mixture was sufficiently heated in a thermostatic bath at 40° C., and then treated in a Henschel mixer at 1000 rpm for 1 minute to promote fibrillation, thereby obtaining an electrolyte mixture. The electrode mixture was placed between parallel metal rolls (temperature: 80°C, rotation speed: 1 m / min) and rolled to obtain an electrolyte mixture sheet. The rolled sheet obtained was again folded in half to be crushed roughly, and the electrolyte mixture was placed between metal rolls (temperature: 80°C, rotation speed: 1 m / min) and rolled to obtain a stronger electrolyte mixture sheet. Thereafter, the electrolyte mixture sheet was placed in a roll press machine and the gap was adjusted so that the final thickness of the electrolyte mixture sheet was 120 μm. Table 7 shows the material types and compositions.

[0451] [Table 7]

[0452] <Strength measurement of solid electrolyte mixture sheet> The solid electrolyte mixture sheet was cut out to prepare a rectangular test piece with a width of 4 mm. A tensile tester (AGS-100NX manufactured by Shimadzu Corporation) was used to measure at a speed of 100 mm / min. The chuck distance was 30 mm. Displacement was applied until breakage, and the maximum stress of the measurement result was taken as the strength of each sample. Comparative Example 6 was set to 100 and compared with Examples 12 to 15, Comparative Example 7 was set to 100 and compared with Example 16, Comparative Example 8 was set to 100 and compared with Example 17, and Comparative Example 9 was set to 100 and compared with Example 18. The samples were ranked from A to E in order of high tensile strength and good electrode strength. A: 230 or more B:180~229 C:120~179 D:105~119 E: Less than 105 The results are shown in Table 8.

[0453] <Flexibility evaluation of solid electrolyte mixture sheet (bending test)> The prepared solid electrolyte mixture sheet was cut into a width of 4 cm and a length of 10 cm to prepare test pieces. Next, these test pieces were wrapped around a Φ10 mm round bar, and the test pieces were visually inspected to confirm the presence or absence of damage such as scratches or cracks. If no damage was observed, a test was performed using a thinner Φ5 mm round bar to confirm damage. Again, if no damage was observed, a test was performed using a thinner Φ2 mm round bar to confirm damage. The results were classified into A to D. A: No damage with Φ2mm rod B: Φ2mm rod damaged C: Φ5mm rod damaged D: Φ10mm rod damaged The results are shown in Table 8.

[0454] <Ionic conductivity of solid electrolyte mixture sheet> The solid electrolyte mixture sheet was cut to an appropriate size and gold was vapor-deposited on both sides. The solid electrolyte mixture sheet was then punched out into a Φ10mm circle using a punch, which was then placed in a pressure cell, the cell's screws were tightened to 8N, and electrodes were attached from the top and bottom of the cell. A schematic diagram of the cross section of the pressure cell used is shown in Figure 1. This sample was measured using an impedance device manufactured by Toyo Corporation at 25°C, AC amplitude modulation of 10 mV, and a frequency of 5 x 10 6 The ionic conductivity was measured at ~0.1 Hz. The results are shown in Table 8.

[0455] [Table 8] [Explanation of symbols]

[0456] 1: Screw 2: Nut 3: Insulation sheet 4: Solid electrolyte mixture sheet 5: Gold vapor deposition 6:Top electrode 7: Lower electrode

Claims

1. A tetrafluoroethylene-based polymer composition used as a binder for electrochemical devices, comprising a tetrafluoroethylene-based polymer and a polymeric compound having an ionic group, the tetrafluoroethylene-based polymer composition having a water content of 0.040 mass% or less based on the tetrafluoroethylene-based polymer composition, and being substantially free of organic solvents.

2. A tetrafluoroethylene-based polymer composition used as a binder for electrochemical devices, comprising a tetrafluoroethylene-based polymer and a polymer compound having an ionic group, the content of the polymer compound being 0.01% by mass or more and 5.0% by mass or less relative to the tetrafluoroethylene-based polymer, and the water content being 0.040% by mass or less relative to the tetrafluoroethylene-based polymer composition.

3. 3. The tetrafluoroethylene polymer composition according to claim 1, which is substantially free of fluorine-containing compounds having a molecular weight of 1,000 or less.

4. The tetrafluoroethylene-based polymer composition according to claim 1 or 2, which is used as a binder for a solid secondary battery.

5. A binder for electrochemical devices consisting essentially of a tetrafluoroethylene-based polymer composition, wherein the tetrafluoroethylene-based polymer composition contains a tetrafluoroethylene-based polymer and a polymer compound having an ionic group, the binder having a water content of 0.040 mass% or less relative to the tetrafluoroethylene-based polymer composition, and the binder for electrochemical devices is substantially free of organic solvents.

6. A binder for electrochemical devices consisting essentially of a tetrafluoroethylene-based polymer composition, wherein the tetrafluoroethylene-based polymer composition contains a tetrafluoroethylene-based polymer and a polymer compound having an ionic group, the content of the polymer compound being 0.01% by mass or more and 5.0% by mass or less relative to the tetrafluoroethylene-based polymer, and the water content being 0.040% by mass or less relative to the tetrafluoroethylene-based polymer composition.

7. The ionic group is —SO ３ M ａ , -PO ３ M ａ and -COOM ａ (In the formula, M ａ represents —H, a metal atom, —NR ２ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ２ 7. The binder for electrochemical devices according to claim 5, wherein the binder is at least one selected from the group consisting of:

8. The ionic group is —SO ３ M ａ and -COOM ａ (In the formula, M ａ is —H or an alkali metal atom.

9. 7. The binder for electrochemical devices according to claim 5, wherein the content of the ionic group is 0.8 meq / g or more with respect to the polymer compound.

10. 7. The binder for electrochemical devices according to claim 5, wherein the total amount of the tetrafluoroethylene-based polymer and the polymer compound is 99.95 mass % or more based on the tetrafluoroethylene-based polymer composition.

11. 7. The binder for electrochemical devices according to claim 5, wherein the content of the polymer compound is 0.08% by mass or more and 1.0% by mass or less with respect to the tetrafluoroethylene-based polymer.

12. 7. The binder for electrochemical devices according to claim 5, wherein the proportion of hydrogen atoms bonded to carbon atoms in the polymer compound that have been substituted with fluorine atoms is 50% or more.

13. 7. The binder for electrochemical devices according to claim 5, wherein the polymer compound has an ion exchange rate of 53 or less.

14. 7. The binder for electrochemical devices according to claim 5, wherein the polymer compound is a water-soluble polymer compound.

15. 7. The binder for electrochemical devices according to claim 5, wherein the polymer compound is at least one selected from the group consisting of a polymer (I) containing polymerization units (I) based on a monomer represented by the following general formula (I), and a compound (II) represented by the following general formula (II): General formula (I): CX １ X ３ =CX ２ R(-CZ １ Z ２ -A ０ ) ｍ (I) (In the formula, X １ and X ３ are each independently F, Cl, H or CF ３ and A ０ is an anionic group; X ２ is H, F, an alkyl group or a fluorine-containing alkyl group; R is a linking group; Z １ and Z ２ are each independently H, F, an alkyl group or a fluorine-containing alkyl group; and m is an integer of 1 or more. General formula (II): () Ｘ ︹ Ａ  ＦＡ１  ＦＡ２ ︹ Ａ ) Ｘ ' (=) (In the formula, R ＦＡ１ is -Rf １ ｐ -R Ｆ -O ｑ - and R ＦＡ２ is -Rf ２ ｐ -R ＦＸ -O ｑ - and R Ｆ is a divalent fluoropolyether group, R ＦＸ is a divalent fluoropolyether group containing an anionic group, Rf １ and Rf ２ each independently represents a C optionally substituted by one or more fluorine atoms; １－６ is an alkylene group, Each p is independently 0 or 1; Each q is independently 0 or 1; X Ａ are each independently a single bond or a divalent to decavalent group, T Ｘ and T Ｘ (i) each independently contains one or more of H, O, and Cl, and does not contain the anionic group; １ ~C ２４ (hydro)(fluoro)carbon groups, and (ii) C containing at least one of said anionic groups. １ ~C ２４ (hydro)(fluoro)carbon groups.)

16. The polymer compound is the polymer (I), and X in the general formula (I) １ and X ３ are each independently F or H; A ０ is -SO ３ M ａ or -COOM ａ (In the formula, M ａ is —H or an alkali metal atom); X ２ is F; R is a fluorinated alkylene group having 1 to 4 carbon atoms and containing an ether bond; Z １ and Z ２ are each independently F or CF ３ 16. The binder for electrochemical devices according to claim 15, wherein m is 1.

17. 7. The binder for electrochemical devices according to claim 5, wherein the standard specific gravity of the tetrafluoroethylene polymer composition is 2.280 or less.

18. 7. The binder for electrochemical devices according to claim 5, wherein the water content of the tetrafluoroethylene-based polymer composition is 0.010% by mass or less.

19. 7. The binder for electrochemical devices according to claim 5, wherein the tetrafluoroethylene polymer composition has an extrusion pressure of 10 MPa or more at a reduction ratio of 100.

20. 7. The binder for electrochemical devices according to claim 5, wherein the tetrafluoroethylene-based polymer composition is stretchable.

21. 7. The binder for electrochemical devices according to claim 5, wherein the tetrafluoroethylene-based polymer is polytetrafluoroethylene.

22. 7. The binder for electrochemical devices according to claim 5, wherein the tetrafluoroethylene-based polymer contains a tetrafluoroethylene unit and a modified monomer unit based on a modified monomer copolymerizable with tetrafluoroethylene.

23. 23. The binder for electrochemical devices according to claim 22, wherein the modified monomer is at least one selected from the group consisting of perfluoro(methyl vinyl ether), hexafluoropropylene, vinylidene fluoride, and chlorotrifluoroethylene.

24. 7. The binder for electrochemical devices according to claim 5, wherein the average primary particle size of the tetrafluoroethylene polymer composition is 100 to 350 nm.

25. 7. The binder for electrochemical devices according to claim 5, wherein the tetrafluoroethylene polymer composition is substantially free of fluorine-containing compounds having a molecular weight of 1,000 or less.

26. 7. The binder for electrochemical devices according to claim 5, wherein the tetrafluoroethylene-based polymer composition is substantially free of any of the fluorine-containing compounds represented by the following formulae: F(CF ２ ) ７ COOM、 F(CF ２ ) ５ COOM、 H(CF ２ ) ６ COOM、 H(CF ２ ) ７ COOM、 CF ３ O(CF ２ ) ３ OCHFCF ２ AOM、 C ３ F ７ OCF(CF ３ )CF ２ OCF(CF ３ )COOM、 CF ３ CF ２ CF ２ OCF(CF ３ )COOM、 CF ３ CF ２ OCF ２ CF ２ OCF ２ COOM、 C ２ F ５ OCF(CF ３ )CF ２ OCF(CF ３ )COOM、 CF ３ OCF(CF ３ )CF ２ OCF(CF ３ )COOM、 CF ２ ClCF ２ CF ２ OCF(CF ３ )CF ２ OCF ２ COOM、 CF ２ ClCF ２ CF ２ OCF ２ CF(CF ３ )OCF ２ COOM、 CF ２ ClCF(CF ３ )OCF(CF ３ )CF ２ OCF ２ COOM、 CF ２ ClCF(CF ３ )OCF ２ CF(CF ３ )OCF ２ COOM, and, 【Chemical 1】 (In each formula, M is H, metal atom, NR １ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium. １ is H or an organic group.

27. 26. The binder for electrochemical devices according to claim 25, wherein the content of the fluorine-containing compound is less than 25 ppb by mass with respect to the tetrafluoroethylene-based polymer composition.

28. 7. The binder for electrochemical devices according to claim 5, which is for use in a secondary battery.

29. The binder for electrochemical devices according to claim 28, which is for use in lithium ion secondary batteries.

30. The binder for electrochemical devices according to claim 28, which is for use in solid secondary batteries.

31. 7. The binder for electrochemical devices according to claim 5, which is for use in capacitors.

32. 7. An electrode mixture comprising the tetrafluoroethylene-based polymer composition according to claim 1 or 2, the binder for electrochemical devices according to claim 5 or 6, and an electrode active material.

33. 7. An electrode comprising the tetrafluoroethylene-based polymer composition according to claim 1 or 2, or the binder for electrochemical devices according to claim 5 or 6, an electrode active material, and a current collector.

34. A secondary battery comprising the electrode according to claim 33.

35. A mixture for an electrolyte layer, comprising the binder for a solid secondary battery according to claim 30 and a solid electrolyte.

36. 36. The mixture for an electrolyte layer according to claim 35, wherein the solid electrolyte is a sulfide-based solid electrolyte or an oxide-based solid electrolyte.

37. A solid secondary battery comprising the mixture for an electrolyte layer according to claim 35.

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