Binder composition for electrode, method for producing same, and secondary battery

Abstract

The invention provides a method for producing a binder composition for an electrode, a binder composition for an electrode, and a secondary battery. A method for producing a binder composition for electrodes, which contains a fluorine-containing polymer, an electrode active material, a conductive material, and water and an organic solvent as a dispersion medium, the method comprising: adding and mixing the electrode active material and the conductive material to the dispersion medium three or more times; next, the fluorine-containing polymer is added and mixed. The binder composition for an electrode manufactured by the manufacturing method of the present invention has high dispersibility even if the particle size of the electrode active material is small, and does not deteriorate the performance of a battery using the binder composition for an electrode.

Description

Technical Field

[0001] The present invention relates to the field of batteries, and particularly to an adhesive composition for an electrode, a method for manufacturing the same, and a secondary battery including the adhesive composition for an electrode. Background Art

[0002] An adhesive composition for an electrode is prepared by dispersing a polymer as an adhesive, an electrode active material, and a conductive material in water. By applying the adhesive composition for an electrode to the surface of a current collector and evaporating the solvent, the battery active material is fixed on the electrode surface (for example, Patent Document 1). The dispersibility of the electrode active material and the conductive material affects battery performance. In particular, the smaller the particle size of the electrode active material, the more difficult it is to disperse in the adhesive composition.

[0003] Prior Art Documents

[0004] Patent Document 1: International Publication No. WO2011 / 055760A1 Summary of the Invention

[0005] An object of the present invention is to provide an adhesive composition for an electrode that has high dispersibility even when the particle size of the electrode active material is small and does not reduce the performance of a battery using the adhesive composition for an electrode, and a method for manufacturing the adhesive composition for an electrode.

[0006] Another object of the present invention is to provide a secondary battery including the above-described adhesive composition for an electrode.

[0007] To achieve the above object, the present inventors conducted intensive studies and found that even when the particle size of the electrode active material is small (for example, 3 μm or less), by adding the electrode active material and the conductive material to a dispersion medium in three or more portions and mixing them, and then adding a fluoropolymer and mixing, an adhesive composition for an electrode having high dispersibility and not reducing the performance of a battery using the adhesive composition for an electrode can be manufactured, thereby completing the present invention.

[0008] The present invention provides the following technical content.

[0009] [1] A method for manufacturing an adhesive composition for an electrode, which is a method for manufacturing an adhesive composition for an electrode including a fluoropolymer, an electrode active material, a conductive material, and water and an organic solvent as a dispersion medium, comprising:

[0010] adding the electrode active material and the conductive material to the dispersion medium in three or more portions and mixing them,

[0011] then, adding the fluoropolymer and mixing.

[0012] [2] The manufacturing method of the binder composition for electrodes as described in [1], wherein the electrode active material contains at least one selected from phosphate-based and manganate-based active materials.

[0013] [3] The manufacturing method of the binder composition for electrodes as described in [1], wherein the electrode active material has an olivine-type or spinel-type crystal structure.

[0014] [4] The manufacturing method of the binder composition for electrodes as described in [1], wherein the secondary particle size of the electrode active material is 3 μm or less.

[0015] [5] The manufacturing method of the binder composition for electrodes as described in [1], wherein the fluoropolymer has a unit composed of tetrafluoroethylene.

[0016] [6] The manufacturing method of the binder composition for electrodes as described in [1], wherein the fluoropolymer has a unit composed of tetrafluoroethylene and a unit composed of propylene.

[0017] [7] The manufacturing method of the binder composition for electrodes as described in [6], wherein the fluoropolymer further has a unit composed of vinylidene fluoride, and the proportion of the unit composed of vinylidene fluoride relative to all units in the fluoropolymer is less than 60 mol%.

[0018] [8] The manufacturing method of the binder composition for electrodes as described in [6], wherein the fluoropolymer does not have a unit composed of vinylidene fluoride.

[0019] [9] The manufacturing method of the binder composition for electrodes as described in [1], wherein the conductive material is at least one selected from carbon black, carbon fiber, carbon nanotube, conductive graphite, and graphene.

[0020]

[10] The manufacturing method of the binder composition for electrodes as described in [1], wherein the organic solvent is at least one selected from N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

[0021]

[11] The manufacturing method of the binder composition for electrodes as described in [1], wherein the content of the organic solvent in the dispersion medium is 1 to 10% by mass.

[0022]

[12] The manufacturing method of the binder composition for electrodes as described in [1], wherein

[0023] the solid content of the binder composition for electrodes is 40 to 50% by mass,

[0024] Based on 100 parts by mass of the solid components in the binder composition for electrodes, the total addition amount of the electrode active material is 90 to 98 parts by mass, the total addition amount of the conductive material is 1 to 5 parts by mass, and the addition amount of the fluoropolymer is 1 to 5 parts by mass.

[0025]

[13] A binder composition for electrodes, which contains a fluoropolymer, an electrode active material, a conductive material, water, and an organic solvent, wherein the initial Coulombic efficiency of a battery having an electrode made from the binder composition for electrodes is 95.8% or more.

[0026]

[14] A binder composition for electrodes, which contains a fluoropolymer, an electrode active material, a conductive material, and water and an organic solvent as a dispersion medium, and is obtained by a method for manufacturing a binder composition for electrodes including the following steps:

[0027] Adding the electrode active material and the conductive material to the dispersion medium in 3 or more portions and mixing them,

[0028] Then, adding the fluoropolymer and mixing them.

[0029]

[15] A secondary battery, which has an electrode obtained by using the binder composition for electrodes described in the above

[13] or

[14] .

[0030] According to the method for manufacturing a binder composition for electrodes of the present invention, even if the particle size of the electrode active material is small, a binder composition for electrodes with high dispersibility can be manufactured without reducing the performance of a battery using the binder composition for electrodes.

[0031] According to the present invention, a secondary battery having the above binder composition for electrodes can also be provided.

[0032] Other aspects, features, and advantages of the present invention will become apparent in the following detailed description. Detailed Description

[0033] The meanings of the following terms in this specification are as described below.

[0034] A "unit" in a polymer can be a group of atoms directly formed from a monomer through a polymerization reaction, or a group of atoms formed by treating a polymer obtained through a polymerization reaction with a specified method to transform a part of the structure. In addition, a unit based on monomer A is also denoted as monomer A unit.

[0035] "The average particle diameter (D50) of the particles" is the volume-based cumulative 50% diameter of the particles obtained by the laser diffraction scattering method. That is, the particle size distribution of the particles is measured by the laser diffraction scattering method, and a cumulative curve is obtained with the total volume of the particles as 100%, and the particle diameter at the point where the cumulative volume reaches 50% on this cumulative curve.

[0036] In this specification, unless otherwise specified, the addition amount, content, concentration, and ratio involved in the specification refer to the addition amount, content, concentration, and ratio based on mass.

[0037] The binder composition for an electrode of the present invention (hereinafter, also referred to as "binder composition") contains a fluoropolymer, an electrode active material, a conductive material, and a dispersion medium. Among them, water and an organic solvent are used as the dispersion medium. The manufacturing method of the binder composition for an electrode of the present invention includes: adding the electrode active material and the conductive material to the dispersion medium in 3 or more times and mixing them, and then adding the fluoropolymer and mixing them. Hereinafter, the binder composition for an electrode of the present invention and its manufacturing method will be described in detail.

[0038] 〔Binder Composition〕

[0039] The binder composition of the present invention contains a fluoropolymer used as a binder. The above-mentioned fluoropolymer is a polymer having a unit composed of tetrafluoroethylene (TFE unit), and preferably a copolymer having a unit composed of tetrafluoroethylene and a unit composed of propylene (TFE unit / P unit).

[0040] The fluorine-containing copolymer of the present invention may further contain a unit composed of vinylidene fluoride (PVDF unit). In the case of containing a unit composed of vinylidene fluoride, the proportion of the unit composed of vinylidene fluoride relative to all the units in the fluoropolymer is less than 60 mol%.

[0041] The fluorine-containing copolymer of the present invention may also contain a fluorine-containing monomer other than vinylidene fluoride or a repeating unit based on a hydrocarbon monomer in a proportion of 10 mol% or less to the extent that the functions of the present invention are not impaired.

[0042] As the fluorine-containing monomer other than vinylidene fluoride, fluorine-containing olefins such as hexafluoropropylene, chlorotrifluoroethylene, (perfluorobutyl)ethylene, etc., and fluorine-containing vinyl ethers such as perfluoropropyl vinyl ether, perfluoromethyl vinyl ether, etc. can be used.

[0043] As the hydrocarbon monomer, α-olefins such as ethylene, 1-butene, etc., vinyl ethers such as ethyl vinyl ether, butyl vinyl ether, hydroxybutyl vinyl ether, etc., and vinyl esters such as vinyl acetate, vinyl benzoate, etc. can be exemplified.

[0044] When the fluorine-containing copolymer used in the present invention contains TFE units, P units, and PVDF units, the composition preferably has a ratio of TFE units / P units / PVDF units in the range of 30 to 85 / 15 to 70 / 0 to 50 (mol%), more preferably 30 to 70 / 20 to 60 / 0 to 40 (mol%).

[0045] The unit composed of vinylidene fluoride should be less, specifically, preferably 25 mol% or less, more preferably 10 mol% or less, further preferably 5 mol% or less, and particularly preferably 1 mol% or less. Most preferably, it does not have a unit composed of vinylidene fluoride.

[0046] When the fluorine-containing copolymer of the present invention does not have a unit composed of vinylidene fluoride, the ideal composition of the fluorine-containing copolymer preferably has a ratio of TFE units / P units of 80 / 20 to 30 / 70 (mol%), more preferably 70 / 30 to 40 / 60 (mol%), and most preferably 60 / 40 to 50 / 50 (mol%).

[0047] If within this composition ratio range, the swelling with respect to the solvent of the electrolyte at high temperature is small, and when integrating the current collector and the electrode, the adhesiveness of the adhesive composition to the current collector is good.

[0048] When using the above-mentioned fluorine-containing copolymer as an adhesive for the electrode, one kind of copolymer can be used, or two or more kinds of copolymers with different polymerization unit compositions can be combined and used. In addition, other high molecular compounds can be used in combination as needed.

[0049] The above-mentioned fluorine-containing copolymer can be manufactured by a known polymerization method, and preferably a radical copolymerization method. There is no particular limitation on the radical polymerization method, and various radical polymerization methods can be used, but preferably a method initiated by an organic or inorganic radical polymerization initiator, light, heat, ionizing radiation, etc. As the polymerization method, it can be manufactured by currently known polymerization methods such as bulk polymerization, suspension polymerization, emulsion polymerization, solution polymerization, etc., and emulsion polymerization is preferred.

[0050] In the adhesive composition of the present invention, by making the molecular weight of the fluorine-containing copolymer within the following range, the electrode active material with a small particle size can be uniformly dispersed in the adhesive composition, forming a highly stable dispersion system, and the following effects can be exerted: even at high temperature, the swelling of the electrode with respect to the electrolyte is small, and the mutual adhesiveness between the current collector of the electrode and the electrode active material is high, and the charge-discharge characteristics are excellent, etc.

[0051] That is, the weight-average molecular weight of the above-mentioned fluorine-containing copolymer is 10,000 to 300,000, preferably 20,000 to 250,000, more preferably 20,000 to 200,000, and particularly preferably 30,000 to 190,000. If the weight-average molecular weight is lower than the lower limit value, it is likely to swell in the electrolyte, and if the molecular weight exceeds the upper limit value, the adhesiveness decreases. The weight-average molecular weight can be adjusted by known methods, such as the addition of a chain transfer agent, control of the polymerization temperature, polymerization pressure, etc.

[0052] The binder composition of the present invention contains water and an organic solvent as a dispersion medium. As the organic solvent, a water-soluble organic solvent (hereinafter also referred to as "water-soluble organic solvent") soluble in water can be used, and at least one of N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide is preferably used, more preferably N-methyl-2-pyrrolidone or N-ethyl-2-pyrrolidone, and particularly preferably N-methyl-2-pyrrolidone.

[0053] As the dispersion medium, the content of the water-soluble organic solvent is preferably small. The content of the organic solvent in the dispersion medium is 1% to 10%, more preferably 2% to 8%, further preferably 2% to 6%, and particularly preferably 3% to 5%. By adding a small amount of the water-soluble organic solvent to water, it is considered to help the binder polymer such as the fluorine-containing polymer to stably disperse the electrode active material particles with a small particle size, obtain a binder composition with stable dispersion, and avoid the electrode sheet from cracking after drying due to uneven slurry dispersion of the binder composition. When the amount of the water-soluble organic solvent added to water exceeds 10%, the stability of the binder composition may be reduced, resulting in aggregation of the electrode active material, etc. during the preparation of the electrode sheet, and the adhesiveness is reduced.

[0054] The content of the binder contained in the binder composition of the present invention is 0.3% to 3%, preferably 0.5% to 2%, and further preferably 0.8% to 1.5%. In addition, the proportion of the fluorine-containing copolymer in the binder can be 60% to 100%, preferably 70% to 95%, more preferably 80% to 90%, and particularly preferably 80%.

[0055] In addition to containing the fluorine-containing copolymer as a binder component, the binder composition of the present invention may contain other binder components commonly used in the art, particularly binders suitable for aqueous systems, such as carboxymethyl cellulose (CMC), methyl cellulose, etc. Carboxymethyl cellulose has good wettability to particles such as electrode active materials and conductive fillers, but has weak suspension ability. By combining with the fluorine-containing copolymer, the dispersion and suspension ability of particles such as electrode active materials and conductive fillers can be further improved, which helps to obtain a binder composition with stable dispersion, and is therefore preferred.

[0056] In the case where the adhesive composition of the present invention contains a fluorine-containing copolymer and carboxymethyl cellulose, the content ratio of the fluorine-containing copolymer to carboxymethyl cellulose can be 50:50 to 99:1, preferably 60:40 to 98:2, more preferably 70:30 to 95:5, still more preferably 80:20 to 90:10, and particularly preferably 80:20.

[0057] The fluorine-containing copolymer used in the adhesive composition of the present invention is preferably emulsified or dispersed in an aqueous medium, and more preferably emulsified or dispersed in the form of particles. A latex state is particularly preferred.

[0058] When the above-mentioned fluorine-containing copolymer is emulsified or dispersed as particles, the average particle size of the fluorine-containing copolymer is preferably 10 to 500 nm, more preferably 20 to 200 nm, further preferably 30 to 150 nm, still further preferably 50 to 150 nm, and particularly preferably 50 to 100 nm. If the average particle size is less than the lower limit value, the entire surface of the electrode active material will be densely covered, so the internal resistance is likely to increase. In addition, if the average particle size is greater than the upper limit value, the adhesive force of the adhesive is likely to decrease. The average particle size of the fine particles of the fluorine-containing copolymer can be adjusted by known methods such as the type and amount of the emulsifier. In addition, the average particle size of the fine particles of the adhesive can be measured by the dynamic light scattering method using a laser zeta potential meter ELS-8000 manufactured by Otsuka Electronics Co., Ltd.

[0059] In the adhesive composition of the present invention, the solid content concentration when using a fluorine-containing copolymer in a latex state is 5% to 95%. More preferably 20% to 60%, and further preferably 30% to 40%. If the concentration is 5% or more, it is preferred because of the good effect as an adhesive. If it is 50% or less, it is preferred because of the good dispersibility.

[0060] The adhesive composition of the present invention can be used for both the positive electrode and the negative electrode according to the type of the contained electrode active material, but is particularly suitable for the positive electrode containing the positive electrode active material. The electrode active material in the present invention preferably contains at least one selected from phosphate-based and manganate-based active materials, and preferably at least one of lithium iron phosphate (LiFePO4, often referred to as LFP), lithium iron manganese phosphate, lithium manganese phosphate, lithium manganate (such as LiMnO2, LiMn2O4), and lithium nickel manganese oxide. In addition, the electrode active material in the present invention preferably has an olivine-type or spinel-type crystal structure. Specifically, it preferably has at least one of lithium iron phosphate and lithium manganese phosphate having an olivine-type crystal structure, and lithium manganate and lithium nickel manganese oxide having a spinel-type crystal structure.

[0061] In the binder composition of the present invention, the secondary particle size of the electrode active material is 3 μm or less. Here, the secondary particle size of the electrode active material refers to the average particle size (D50) of the particles. The above-mentioned secondary particle size is preferably 0.1 to 2.5 μm, more preferably 0.5 to 2 μm, and further preferably 1 to 2 μm. Research shows that in the case of using an electrode active material with a smaller secondary particle size, the polarization heat of the battery can be reduced, and the discharge capacity of the metal ion secondary battery can be significantly improved. The smaller the particle size of the electrode active material, the more likely the particles are to aggregate and the more difficult it is to disperse in the binder composition, ultimately affecting the battery performance. However, in the binder composition of the present invention, a specific dispersion system and dispersion method are used, and even when the particle size of the electrode active material is small, a binder composition with high dispersibility can be manufactured without reducing the performance of the battery using this electrode binder composition.

[0062] In the binder composition of the present invention, the content of the electrode active material is 30 to 60 parts by mass, preferably 40 to 50 parts by mass, and further preferably 40 to 45 parts by mass, based on 100 parts by mass of the binder composition.

[0063] The binder composition of the present invention contains a conductive material. By including a conductive material, the electrical contact between the electrode active materials can be improved, and the resistance within the active material layer can be reduced. As the conductive material, at least one selected from carbon black, carbon fiber, carbon nanotubes, conductive graphite, and graphene is preferred, and it is more preferred to use conductive carbon black and carbon nanotubes in combination. In the binder composition, the content of the conductive material is preferably 1 to 10 parts by mass, and more preferably 2 to 5 parts by mass, based on 100 parts by mass of the electrode active material. If the conductive material is contained in this range of content, the effect of reducing the resistance is large and good by adding a small amount of the conductive material.

[0064] In the binder composition of the present invention, surfactants, emulsifiers, dispersants, defoamers, thickeners, etc. commonly used in the art can also be added within the range that does not affect the effects of the present invention.

[0065] In some preferred embodiments of the adhesive composition according to the present invention, the solid content in the adhesive composition for electrodes is preferably 40 to 50%, more preferably 42 to 45%. Based on 100 parts by mass of the solid components in the adhesive composition for electrodes, the addition amount of the above electrode active material is 90 to 98 parts by mass, preferably 93 to 96 parts by mass, more preferably 95 to 96 parts by mass, the addition amount of the above conductive material is 1 to 5 parts by mass, preferably 1 to 4 parts by mass, more preferably 1 to 3 parts by mass, and the addition amount of the above fluoropolymer is 1 to 5 parts by mass, preferably 1 to 4 parts by mass, more preferably 1 to 3 parts by mass. When the adhesive composition contains a fluoropolymer and carboxymethyl cellulose as adhesives, the total addition amount of the fluoropolymer and carboxymethyl cellulose is 1 to 5 parts by mass, preferably 1 to 4 parts by mass, more preferably 1 to 3 parts by mass.

[0066] In some preferred embodiments, based on 100 parts by mass of the solid components in the adhesive composition for electrodes, the ratio of the contents of the electrode active material, the conductive material, and the adhesive is 95:2.5:2.5.

[0067] For the adhesive composition according to the present invention, even if the secondary particle size of the electrode active material particles is small, due to the use of a specific fluoropolymer and a dispersion medium, a stable dispersion system can be formed. The electrode sheet prepared using the adhesive composition of the present invention is not easily broken after drying, and the initial Coulombic efficiency of the battery using this electrode sheet is high (more than 95.8%), and it can be used to manufacture a battery with excellent electrical properties such as the capacity and cycle stability of the battery.

[0068] 〔Manufacturing method of the adhesive composition〕

[0069] The adhesive composition for electrodes of the present invention can be prepared by the manufacturing method of the adhesive composition for electrodes of the present invention.

[0070] The adhesive composition for electrodes of the present invention contains a fluoropolymer, an electrode active material, a conductive material, and water and an organic solvent as a dispersion medium. By adding the electrode active material and the conductive material to the dispersion medium in more than 3 times and mixing, and then adding the fluoropolymer and mixing, the adhesive composition of the present invention can be prepared. Among them, the preferred forms of the fluoropolymer, the electrode active material, the conductive material, and the dispersion medium are as described above.

[0071] In some preferred embodiments, the binder composition for the electrode comprises a fluoropolymer, carboxymethyl cellulose (CMC), an electrode active material, a conductive material, and water and N-methyl-2-pyrrolidone (NMP) as a dispersion medium. Its manufacturing method includes: mixing an aqueous CMC solution with water and NMP to prepare a dispersion, then adding the electrode active material and the conductive material more than 3 times to the above dispersion and mixing, and then adding the fluoropolymer and mixing.

[0072] The concentration of the above aqueous CMC solution is 1 to 10% by mass, preferably 2 to 5% by mass.

[0073] The mass ratio of the above water to NMP in the mixture is 90:10 to 98:2, preferably 92:8 to 96:4, more preferably 93:7 to 95:5, and particularly preferably 95:5.

[0074] When the electrode active material and the conductive material are added more than 3 times, it is preferred that the electrode active material and the conductive material are added in a certain ratio each time. For example, when the addition amount of the electrode active material is 90 to 98 parts by mass and the addition amount of the conductive material is 1 to 5 parts by mass relative to 100 parts by mass of the solid components in the binder composition for the electrode, the electrode active material and the conductive material are added in a ratio of 90 to 98:1 to 5.

[0075] After adding the electrode active material and the conductive material, it is preferred to use a stirrer to mix to obtain a dispersion. As the stirrer, there is no particular limitation, and conventional stirrers, mixers, homogenizers, etc. in the art can be used. From the perspective of being able to stir evenly and being able to defoam, it is preferred to use a planetary homogenizer.

[0076] In some preferred embodiments, the electrode active material and the conductive material are added 3 times. After the first addition, the solid component content in the dispersion reaches 20% by mass or more and less than 30% by mass, preferably 25% by mass. After the second addition, the solid component content in the dispersion reaches 30% by mass or more and less than 40% by mass, preferably 35% by mass. After the third addition, the solid component content in the dispersion reaches 40% by mass or more and less than 50% by mass, preferably 45% by mass.

[0077] In addition, when mixing the CMC aqueous solution with water and NMP, a stirrer can be used for stirring. To avoid foaming caused by intense stirring, stirring is carried out at a relatively low stirring rate. For example, the stirring rate is 800 to 1500 rpm, preferably 1200 rpm, and the stirring time is 20 to 50 minutes, preferably 30 minutes. When stirring is carried out after the first, second, and third additions above, a relatively high stirring rate can be used for stirring to shorten the stirring time to improve efficiency. For example, the stirring rate is 1800 to 2500 rpm, preferably 2000 to 2200 rpm, and the stirring time is 5 to 30 minutes, preferably 10 to 15 minutes.

[0078] The above describes the case where the electrode active material and the conductive material are added in 3 times. However, in order to obtain a more stable dispersion of the binder composition, they can also be added in 4 times, 5 times, 6 times, 8 times, or 10 times. On the other hand, from the perspective of improving the addition efficiency or simplifying the operation process, it is preferably controlled to be added less than 5 times. In the case of adding in 4 times or more, the solid content reached after the first addition is the same as the first addition in the case of adding in 3 times above, and the solid content reached after the last addition is the same as the third addition in the case of adding in 3 times above. In addition to this, the solid content reached during the intermediate addition can be appropriately adjusted and designed.

[0079] When adding the fluoropolymer, the total content of the added fluoropolymer and CMC is added in an amount of 2 to 5 parts by mass relative to 100 parts by mass of the solid content in the electrode binder composition, and preferably the mass ratio of the fluoropolymer to CMC is 80:20 to 90:10. After adding the fluoropolymer, a ball mill can be used for homogenizing mixing, and a planetary ball mill is preferably used. When using a planetary ball mill, the stirring rate is 300 to 800 rpm, preferably 400 to 500 rpm, and the stirring time is 15 to 60 seconds, preferably 20 to 30 seconds. By using a ball mill to stir at a low stirring rate, the materials can be fully homogenized and mixed to obtain a dispersion liquid with high dispersion stability and less foaming.

[0080] In some preferred embodiments, the binder composition for electrodes comprises a fluoropolymer, CMC, a positive electrode active material, a conductive material, water, and NMP. Among them, the contents of the fluoropolymer, CMC, the positive electrode active material, and the conductive material in the solid content of the binder composition are 2.0% by mass, 0.5% by mass, 95% by mass, and 2.5% by mass, respectively. Its manufacturing method includes: adding an aqueous CMC solution to a mixed solvent of water and NMP and stirring to obtain a dispersion, then adding the positive electrode active material and the conductive material for the first time in a mass ratio of 95:2.5 and stirring until the solid content in the dispersion reaches 25% by mass, then adding the positive electrode active material and the conductive material for the second time in a mass ratio of 95:2.5 and stirring until the solid content in the dispersion reaches 35% by mass, then adding the positive electrode active material and the conductive material for the third time in a mass ratio of 95:2.5 and stirring until the solid content in the dispersion reaches 45% by mass, and finally adding the latex of the fluoropolymer and homogenizing and mixing using a ball mill.

[0081] According to the manufacturing method of the binder composition of the present invention, by adding the positive electrode active material particles and the conductive material particles that are prone to aggregation in proportion more than three times, the aggregation and precipitation between the particles can be effectively inhibited. Even if the particle size of the electrode active material is small, a binder composition for electrodes with high dispersibility can be manufactured without reducing the performance of the battery using the binder composition for electrodes.

[0082] 〔Secondary battery〕

[0083] A secondary battery generally includes a positive electrode, a negative electrode, a separator, and an electrolyte. In the secondary battery of the present invention, the electrode (hereinafter also referred to as the secondary battery electrode) prepared using the binder composition of the present invention can be used for either the positive electrode or the negative electrode, or for both. In a secondary battery used for either the positive electrode or the negative electrode, as the counter electrode, a lithium alloy such as lithium metal or a lithium aluminum alloy can be used.

[0084] The manufacturing method of the secondary battery electrode of the present invention is a method of coating the binder composition for electrodes of the present invention on a current collector and then removing the dispersion medium. In addition, after removing the dispersion medium, it is preferably pressure-formed into a desired thickness as needed.

[0085] The manufacturing method of the secondary battery electrode of the present invention can be applied to both the positive electrode and the negative electrode. When manufacturing the positive electrode, it is preferable to use the positive electrode active material as the battery active material, coat the binder composition of the present invention on the positive electrode current collector, and then remove the dispersion medium.

[0086] As a method for coating the binder composition of the present invention on a current collector, various coating methods can be cited. For example, a method of coating using a coating tool such as a doctor blade can be cited. There is no particular limitation on the coating temperature, but a temperature near room temperature is generally preferred.

[0087] Removal of the dispersion medium is generally preferably carried out by drying at room temperature or by heating. Drying can be carried out using various dryers, and for example, a heated vacuum dryer can be cited. There is no particular limitation on the drying temperature, but a temperature in the range of room temperature to 150 °C is generally preferred.

[0088] As an extrusion method, a die press or a roll press can be used. The thickness of the coated layer of the binder composition, in terms of the thickness after drying, or in the case of further extrusion, in terms of the thickness after extrusion, is preferably 0.5 to 2000 μm, more preferably 1 to 1000 μm, and particularly preferably 10 to 500 μm.

[0089] As the current collector of the present invention, any current collector made of a conductive material can be used without particular limitation. Generally, metal foils such as aluminum, nickel, stainless steel, and copper, metal meshes, metal porous bodies, etc. can be cited. Aluminum is preferably used as the positive electrode current collector, and copper is preferably used as the negative electrode current collector. The thickness of the current collector is preferably 1 to 100 μm. If it is less than 1 μm, the durability of the battery is insufficient and the reliability of the battery may be low. In addition, if it exceeds 100 μm, the mass of the battery increases.

[0090] The electrode for a secondary battery of the present invention can be used in a battery of any shape such as cylindrical, sheet-shaped, or square-shaped.

[0091] Moreover, a secondary battery in which the positive electrode and / or the negative electrode uses the electrode of the present invention and the positive electrode and the negative electrode are accommodated in a case together with a separator and an electrolyte has high reliability even at high temperatures.

[0092] As the separator, a microporous polymer membrane can be used, and as its material, polypropylene resin, polyethylene resin, polypropylene-polyethylene-polypropylene, etc. can be cited.

[0093] As the solvent of the electrolyte, aprotic organic solvents can be cited, such as isopropyl carbonate, ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, γ-butyrolactone, diethoxyethane, etc. In addition, as the electrolyte, lithium salts such as LiClO4, LiBF4, LiPF6, LiAsF5, CF3SO3Li, (CF3SO2)2NLi, etc. can be cited.

[0094] In some preferred embodiments, the adhesive composition of the present invention is used, and a positive electrode containing a positive electrode active material is manufactured according to the method for manufacturing an electrode for a secondary battery described above. A secondary battery is assembled through the following steps: (1) Place the obtained positive electrode sheet in the center of the positive electrode case, drop an electrolyte solution thereon, and completely wet the positive electrode sheet; (2) Place the separator flat on the positive electrode sheet, and then drop an electrolyte solution to completely wet the separator; (3) Place a lithium sheet as a counter electrode on the separator; (4) Place a gasket and a spring sheet on the lithium sheet in this order so that they are in the center position of the battery, and then fasten the negative electrode case; (5) Use a packaging machine to perform pressure packaging to obtain a button-type half cell.

[0095] Example

[0096] The constitution and advantages of the present invention will be further described below through examples. However, it should be understood that the following examples are only illustrative of the implementation of the present invention and are not intended to limit the protection scope of the present invention.

[0097] [Example 1]

[0098] Add 3.947 g of an aqueous solution of 2% by mass CMC (DAICEL CORPORATION, CMC2200) to a mixed solvent of 14.25 g of water and 0.75 g of NMP (water / NMP = 95 / 5), and mechanically stir at a rotation speed of 1200 revolutions per minute for 30 minutes to obtain a dispersion.

[0099] (First addition)

[0100] Add 6.048 g of LFP (BEIDA ADVANCED TECHNOLOGY INDUSTRIAL CO., LTD., P600A, D50 is 0.9 - 1.3 μm) as a positive electrode active material, 0.127 g of carbon black Super P (GUANGDONG ZHUGUANG NEW ENERGY TECHNOLOGY CO., LTD., MA-EN-CO-01) as a conductive material, and 0.032 g of vapor-grown carbon fiber VGCF (JIANGSU XIANFENG NANOMATERIALS TECHNOLOGY CO., LTD., XFM60) (LFP / Super P / VGCF = 95 / 2.0 / 0.5) to the obtained dispersion to make the solid content in the dispersion reach 25% by mass. After addition, use a planetary homogenizer (KURABO Mazerustar planetary stirring and defoaming machine) to homogenize at 2000 revolutions per minute for 10 minutes.

[0101] (Second addition)

[0102] Add 3.756 g of LFP, 0.079 g of Super P, and 0.02 g of VGCF (the mass ratio of LFP, Super P, and VGCF added is 95 / 2.0 / 0.5) to the obtained dispersion to make the solid content in the dispersion reach 35% by mass. After the addition, use a planetary homogenizer (KURABO Mazerustar planetary stirring and defoaming machine) to homogenize at 2000 revolutions per minute for 10 minutes.

[0103] (Third addition)

[0104] Add 5.196 g of LFP, 0.11 g of Super P, and 0.027 g of VGCF (the mass ratio of LFP, Super P, and VGCF added is 95 / 2.0 / 0.5) to the obtained dispersion to make the solid content in the dispersion reach 45% by mass. After the addition, use a planetary homogenizer (KURABO Mazerustar planetary stirring and defoaming machine) to homogenize at 2000 revolutions per minute for 10 minutes.

[0105] (Add binder)

[0106] Finally, add 0.957 g of AFLAS150CS latex (AGC Inc., 150CS LATEX, TFE / P latex with a solid content of 33% by mass) as the binder, and use a ball mill (QM-3SP04 planetary ball mill) to ball mill at 500 revolutions per minute for 0.5 minutes to obtain a uniformly mixed binder composition A1 for the electrode.

[0107] The solid content of the binder composition A1 for the electrode is 44.7% by mass, and the content ratio of LFP, Super P, VGCF, AFLAS, and CMC in the solid components is 95:2.0:0.5:2.0:0.5.

[0108] [Comparative Example 1]

[0109] Add 3.947 g of a 2% by mass aqueous solution of CMC to a mixed solvent of 14.25 g of water and 0.75 g of NMP (water / NMP = 95 / 5), and mechanically stir at a rotation speed of 1200 revolutions per minute for 30 minutes to prepare a dispersion.

[0110] (First addition)

[0111] To the obtained dispersion, 6.048 g of LFP as the positive electrode active material, 0.127 g of Super P as the conductive material, and 0.032 g of VGCF (LFP / Super P / VGCF = 95 / 2.0 / 0.5) were added to make the solid content in the dispersion reach 25% by mass. After the addition, a planetary homogenizer (KURABO Mazerustar planetary stirring and defoaming machine) was used to homogenize at 2000 revolutions per minute for 10 minutes.

[0112] (Second addition)

[0113] To the obtained dispersion, 8.952 g of LFP, 0.189 g of Super P, and 0.047 g of VGCF (LFP / Super P / VGCF = 95 / 2.0 / 0.5) were added to make the solid content in the dispersion reach 45% by mass. After the addition, a planetary homogenizer (KURABO Mazerustar planetary stirring and defoaming machine) was used to homogenize at 2000 revolutions per minute for 10 minutes.

[0114] (Addition of binder)

[0115] Finally, 0.957 g of AFLAS150CS latex (solid content 33% by mass) was added, and after ball milling with a ball mill (QM-3SP04 planetary ball mill) at 500 revolutions per minute for 0.5 minutes, the binder composition B1 for the electrode was obtained. There were obvious undispersed solid particles in the binder composition B1 for the electrode, and the dispersion was uneven.

[0116] [Comparative Example 2]

[0117] 15 g of LFP, 0.316 g of Super P, and 0.079 g of VGCF were placed in a mortar and ground until there was no obvious granular feeling, and then dry mixed with a planetary homogenizer (KURABO Mazerustar planetary stirring and defoaming machine) at a rotational speed of 2000 revolutions per minute for 2 minutes.

[0118] 1.07 g of 2% CMC aqueous solution, 3.86 g of water, and 0.203 g of NMP were added. After the addition, the solid content reached 75% by mass, and a planetary homogenizer (KURABO Mazerustar planetary stirring and defoaming machine) was used to homogenize at a rotational speed of 2000 revolutions per minute for 10 minutes.

[0119] Then, 1.077 g of 2% CMC aqueous solution, 3.89 g of water, and 0.205 g of NMP were added. After the addition, the solid content reached 60% by mass, and a planetary homogenizer (KURABO Mazerustar planetary stirring and defoaming machine) was used to homogenize at a rotational speed of 2000 revolutions per minute for 10 minutes.

[0120] Next, 1.8 g of a 2% by mass aqueous CMC solution, 6.50 g of water, and 0.342 g of NMP were added. After the addition, the solid content reached 45% by mass. A planetary homogenizer (KURABO Mazerustar planetary stirring and defoaming machine) was used to homogenize at a speed of 2000 revolutions per minute for 10 minutes.

[0121] Finally, 0.957 g of AFLAS 150CS latex (solid content 33% by mass) was added, and after ball milling for 0.5 minutes at 500 revolutions per minute using a ball mill (QM-3SP04 planetary ball mill), the binder composition B2 for the electrode was obtained. There were obvious undispersed solid particles in the binder composition B2 for the electrode, and the dispersion was uneven.

[0122] [Comparative Example 3]

[0123] 3.947 g of a 2% by mass aqueous CMC solution was added to 15 g of water, and mechanically stirred at a speed of 1200 revolutions per minute for 30 minutes to prepare a dispersion.

[0124] (First addition)

[0125] To the obtained dispersion, 6.048 g of LFP as the positive electrode active material, 0.127 g of Super P as the conductive material, and 0.032 g of VGCF (LFP / Super P / VGCF = 95 / 2.0 / 0.5) were added to make the solid content in the dispersion reach 25% by mass. After the addition, a planetary homogenizer (KURABO Mazerustar planetary stirring and defoaming machine) was used to homogenize at 2000 revolutions per minute for 10 minutes.

[0126] (Second addition)

[0127] To the obtained dispersion, 3.756 g of LFP, 0.079 g of Super P, and 0.02 g of VGCF (the addition mass ratio of LFP to Super P and VGCF was 95 / 2.0 / 0.5) were added to make the solid content in the dispersion reach 35% by mass. After the addition, a planetary homogenizer (KURABO Mazerustar planetary stirring and defoaming machine) was used to homogenize at 2000 revolutions per minute for 10 minutes.

[0128] (Third addition)

[0129] Add 5.196 g of LFP, 0.11 g of Super P, and 0.027 g of VGCF (the mass ratio of LFP to Super P and VGCF is 95 / 2.0 / 0.5) to the obtained dispersion to make the solid content in the dispersion reach 45% by mass. After addition, use a planetary homogenizer (KURABO Mazerustar planetary stirring and defoaming machine) to homogenize at 2000 revolutions per minute for 10 minutes.

[0130] (Add binder)

[0131] Finally, add 0.957 g of AFLAS150CS latex (solid content 33% by mass), and use a ball mill (QM-3SP04 planetary ball mill) to ball mill at 500 revolutions per minute for 0.5 minutes to obtain a uniformly mixed binder composition B3 for the electrode.

[0132] [Comparative Example 4]

[0133] Put 15 g of LFP, 0.316 g of Super P, and 0.079 g of VGCF into a mortar and grind until there is no obvious particle feeling, then use a planetary homogenizer (KURABO Mazerustar planetary stirring and defoaming machine) to dry mix at a speed of 2000 revolutions per minute for 2 minutes.

[0134] Add 1.07 g of 2% CMC aqueous solution and 4.063 g of water. After addition, the solid content reaches 75% by mass, and use a planetary homogenizer (KURABO Mazerustar planetary stirring and defoaming machine) to homogenize at a speed of 2000 revolutions per minute for 10 minutes.

[0135] Then add 1.077 g of 2% CMC aqueous solution and 4.095 g of water. After addition, the solid content reaches 60% by mass, and use a planetary homogenizer (KURABO Mazerustar planetary stirring and defoaming machine) to homogenize at a speed of 2000 revolutions per minute for 10 minutes.

[0136] Then add 1.8 g of 2% CMC aqueous solution and 6.842 g of water. After addition, it reaches a solid content of 45% by mass, and use a planetary homogenizer (KURABO Mazerustar planetary stirring and defoaming machine) to homogenize at a speed of 2000 revolutions per minute for 10 minutes.

[0137] Finally, add 0.957 g of AFLAS150CS latex (solid content 33% by mass), and use a ball mill (QM-3SP04 planetary ball mill) to ball mill at 500 revolutions per minute for 0.5 minutes to obtain a binder composition B4 for the electrode. There are obvious undispersed solid particles in this binder composition B4 for the electrode, and the dispersion is uneven.

[0138] [Comparative Example 5]

[0139] Put 15 g of LFP, 0.316 g of Super P, and 0.079 g of VGCF into a mortar and grind until there is no obvious granular feeling, then use a planetary homogenizer (KURABO Mazerustar planetary stirring degassing machine) to dry mix at a speed of 2000 revolutions per minute for 2 minutes.

[0140] Then add 6.8 g of an NMP solution of 2.7 mass% polyvinylidene fluoride (PVDF, HSV900 produced by Arkema) to make the solid content after addition reach 70 mass%, and use a planetary homogenizer (KURABO Mazerustar planetary stirring degassing machine) to homogenize at a speed of 2000 revolutions per minute for 10 minutes.

[0141] Then add 7.815 g of an NMP solution of 2.7 mass% polyvinylidene fluoride (PVDF, HSV900 produced by Arkema). After addition, the solid content reaches 52 mass%. Use a planetary homogenizer (KURABO Mazerustar planetary stirring degassing machine) to homogenize at a speed of 2000 revolutions per minute for 10 minutes to obtain a uniformly mixed binder composition B5 for the electrode.

[0142] The compositions and appearance evaluation results of the binder compositions for the electrodes in Example 1 and Comparative Examples 1 - 5 are summarized in Table 2.

[0143] [Table 2]

[0144]

[0145] <Manufacture of the positive electrode sheet>

[0146] The positive electrode binder compositions obtained in Example 1, Comparative Example 3, and Comparative Example 5 were uniformly dispersed, and were used to manufacture positive electrode sheets for further electrical property evaluation. The positive electrode binder compositions obtained in Comparative Examples 1 - 2 and 4 were not uniformly dispersed and were not further evaluated for electrical properties.

[0147] For the positive electrode binder composition A1 obtained in Example 1, use an automatic film coater (brand: BEVS; model: 1811) to uniformly coat it on an aluminum foil current collector with a thickness of 16 μm, with a coating thickness of 400 μm, and then place it in an 80 °C vacuum drying oven to dry for 8 hours to remove the solvent. After drying, roll it at room temperature under the condition that the coating layer becomes 71 μm to obtain an electrode sheet. Use a manual punching machine to cut the above electrode sheet to obtain a positive electrode sheet specimen with a diameter of 12 mm.

[0148] For the binder composition for the positive electrode obtained in Comparative Example 3, it was uniformly coated on an aluminum foil current collector with a thickness of 16 μm using an automatic film coater (brand: BEVS; model: 1811), with a coating thickness of 400 μm, and then placed in a vacuum drying oven at 80 °C for 8 hours to remove the solvent. After drying, obvious cracks occurred on the surface of the electrode sheet. From this, it can be known that the binder composition for the positive electrode prepared in Comparative Example 3 is not suitable for manufacturing the positive electrode, so it is not further evaluated.

[0149] For the binder composition B5 for the positive electrode obtained in Comparative Example 5, it was uniformly coated on an aluminum foil current collector with a thickness of 16 μm using an automatic film coater (brand: BEVS; model: 1811), with a coating thickness of 350 μm, and then placed in a vacuum drying oven at 80 °C for 8 hours to remove the solvent. After drying, it was calendered at room temperature using a roll press under the condition that the coating layer became 70 μm to obtain an electrode sheet. The above electrode sheet was cut using a manual punching machine to obtain a positive electrode sheet sample with a diameter of 12 mm.

[0150] <Button-type half-cell assembly>

[0151] The positive electrode sheet sample prepared as above was transferred to a glove box filled with argon and assembled into a 2032 button-type half-cell, where a pure lithium sheet was used as the counter electrode and a 2325 polypropylene-polyethylene-polypropylene (PP-PE-PP) membrane was used as the separator. The electrolyte used was a mixed solution of ethylene carbonate (EC) and diethyl carbonate (DEC) (volume ratio 1:1) containing 1 M lithium hexafluorophosphate (LiPF6), and 10% by volume of fluoroethylene carbonate (FEC) was added.

[0152] The specific assembly steps of the above button-type half-cell are as follows: (1) Place the positive electrode sheet in the center of the positive electrode case, and drop the electrolyte on it to completely wet the positive electrode sheet; (2) Place the separator flat on the positive electrode sheet, and then drop the electrolyte to completely wet the separator; (3) Place the lithium sheet as the counter electrode on the separator; (4) Place the gasket and spring piece on the lithium sheet in turn to make it in the center position of the battery, and then fasten the negative electrode case; (5) Use a packaging machine for pressure packaging to obtain a button-type half-cell.

[0153] <Electrochemical testing>

[0154] After the prepared 2032 button-type half-cell was left standing for 6 h, testing was started. The battery was subjected to a constant current charge-discharge cycle test using a Blue-Energy battery test system in the voltage range of 2.5 - 4.0 V.

[0155] <Peel strength testing>

[0156] The peel strength of the electrode sheet was tested according to GB / T 2792—1998, and the specific method is as follows:

[0157] 1. After rolling the electrode sheet, it was cut into long strips with a width of 19 mm.

[0158] 2. The side coated with the electrode adhesive composition was pasted on the single-sided adhesive tape, and a rolling wheel was used to roll back and forth 5 times to remove air bubbles.

[0159] 3. The side not coated with the electrode adhesive composition was bonded to the steel plate using double-sided adhesive tape.

[0160] 4. One end of the electrode sheet and the tape were respectively fixed on the tensile testing machine through clamps, and the tape was peeled from the electrode sheet at a speed of 10 mm·min -1 at an angle of 180° using a universal tensile testing machine.

[0161] <Flexibility Test>

[0162] The flexibility of the electrode sheet was tested by winding the electrode sheet. Using steel cores with diameters of 5 mm, 2.5 mm, 1 mm, and 0.5 mm, the rolled electrode sheet was wound around the surface of the steel core, and the surface coating of the electrode sheet was observed for cracks or peeling. If there were no such phenomena, it was judged as passing the test and marked as "〇"; if there were such phenomena, it was judged as failing the test and marked as "×".

[0163] The relevant parameters of the electrode sheets prepared using the electrode adhesive compositions of Example 1 and Comparative Example 5, as well as the test results of electrical properties, peel strength, and flexibility, are shown in Table 3.

[0164] [Table 3]

[0165]

[0166] Compared with Comparative Examples 1 and 2, in Example 1, by adding the active material and the conductive agent in multiple times (three times or more) in the mixed liquid, the problem that the active material and the conductive agent with relatively small secondary particle sizes such as lithium iron phosphate are not easily dispersed in water was solved.

[0167] Compared with Comparative Example 3, in Example 1, a small amount of organic solvent with a boiling point higher than that of water was added to the aqueous slurry. When the electrode sheet was dried, water evaporated preferentially, and the organic solvent ensured the wettability of the interface at the interface between the current collector and the electrode slurry, and did not crack due to the too large surface tension difference between the aluminum current collector and the aqueous electrode slurry when the drying was completed.

[0168] Compared with Comparative Example 5, in Example 1, water was used to replace the flammable organic solvent during the preparation of the slurry, making the electrode manufacturing process more environmentally friendly.

[0169] As can be seen from the test results of Example 1 in Table 3, the electrode sheet prepared using the binder composition for electrodes of the present invention has a high peel strength after rolling, is not easily peeled off, and has excellent flexibility. Even when wound and bent, cracks or peeling do not occur on the coating surface. In addition, when the electrode sheet prepared using the binder composition for electrodes of the present invention is used in a secondary battery, the initial Coulombic efficiency is above 95.8%, and a battery with a higher initial Coulombic efficiency is obtained; and the initial capacity is 138.6 mAh / g, and the capacity after 100 cycles is 119.9 mAh / g, without degrading the performance of the battery.

[0170] In contrast, the binder composition for electrodes of Comparative Example 5 uses PVDF as the binder. As a result, the peel strength of the electrode sheet prepared using this binder composition for electrodes is significantly lower than that of Example 1 after rolling, and the initial Coulombic efficiency is 91.9%, which is lower than that of Example 1.

[0171] Industrial applicability

[0172] The manufacturing method of the binder composition for electrodes of the present invention can manufacture a binder composition for electrodes that has high dispersibility even when the particle size of the electrode active material is small and does not degrade the performance of the battery using the binder composition for electrodes, as well as a secondary battery using the above binder composition for electrodes.

[0173] Finally, it should be understood that the above descriptions of the embodiments and examples are illustrative in all aspects and do not constitute a limitation to the present invention. Those of ordinary skill in the art can make various improvements without creative labor within the scope of the spirit of the present invention. The scope of the present invention is represented by the claims, rather than by the above embodiments or examples. In addition, the scope of the present invention includes all changes within the meaning and scope equivalent to the claims.

Claims

1. A method for manufacturing an electrode binder composition, which is a method for manufacturing an electrode binder composition containing a fluoropolymer, an electrode active material, a conductive material, and water and an organic solvent as a dispersion medium, comprising: The electrode active material and the conductive material are added to the dispersion medium in more than 3 times and mixed. Next, the fluoropolymer is added and mixed.

2. The method for manufacturing an electrode binder composition according to claim 1, wherein, The electrode active material contains at least one selected from phosphate-based and manganate-based active materials.

3. The method for manufacturing an electrode binder composition according to claim 1, wherein, The electrode active material has an olivine-type or spinel-type crystal structure.

4. The method for manufacturing an electrode binder composition according to claim 1, wherein, The secondary particle size of the electrode active material is 3 μm or less.

5. The method for manufacturing an electrode binder composition according to claim 1, wherein, The fluoropolymer has a unit composed of tetrafluoroethylene.

6. The method for manufacturing an electrode binder composition according to claim 1, wherein, The fluoropolymer has a unit composed of tetrafluoroethylene and a unit composed of propylene.

7. The method for manufacturing an electrode binder composition according to claim 6, wherein, The fluoropolymer further has a unit composed of vinylidene fluoride. And the proportion of the unit composed of vinylidene fluoride relative to all the units in the fluoropolymer is less than 60 mol%.

8. The method for manufacturing an electrode binder composition according to claim 6, wherein, The fluoropolymer does not have a unit composed of vinylidene fluoride.

9. The method for manufacturing an electrode binder composition according to claim 1, wherein, The conductive material is at least one selected from carbon black, carbon fiber, carbon nanotube, conductive graphite, and graphene.

10. The method for manufacturing an electrode binder composition according to claim 1, wherein, The organic solvent is at least one selected from N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

11. The method for manufacturing an electrode binder composition according to claim 1, wherein, The content of the organic solvent in the dispersion medium is 1 to 10% by mass.

12. The method for manufacturing an electrode binder composition according to claim 1, wherein, The solid content of the electrode binder composition is 40 to 50% by mass. Relative to 100 parts by mass of the solid components in the electrode binder composition, the total addition amount of the electrode active material is 90 to 98 parts by mass, the total addition amount of the conductive material is 1 to 5 parts by mass, and the addition amount of the fluoropolymer is 1 to 5 parts by mass.

13. An electrode binder composition, which contains a fluoropolymer, an electrode active material, a conductive material, water and an organic solvent, wherein, The initial Coulombic efficiency of the battery having an electrode made of the electrode binder composition is 95.8% or more.

14. An electrode binder composition, which contains a fluoropolymer, an electrode active material, a conductive material, and water and an organic solvent as a dispersion medium, and is obtained by a method for manufacturing an electrode binder composition including the following steps: The electrode active material and the conductive material are added to the dispersion medium in more than 3 portions and mixed. Next, the fluorine-containing polymer is added and mixed.

15. A secondary battery including an electrode produced using the electrode binder composition according to claim 13 or 14.

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