Slurry, electrode manufacturing method and battery manufacturing method

Abstract

This slurry contains carbon black in a liquid medium, wherein: the average primary particle diameter of the carbon black is 17-30 nm; the crystallite size (Lc) of the carbon black is 15-26 Å; and, in the particle size distribution on a volume basis, as measured by laser diffraction / scattering, of the particle group generated by combining the secondary particles of the carbon black in the slurry and tertiary particles provided by aggregation of the secondary particles of the carbon black, D50 (µm) is 0.5-0.9 µm and the ratio (D50 / (D90-D10)) of D50 (µm) to the difference between D90 (µm) and D10 (µm) is 0.25-0.5.

Description

[Technical Field]

[0001] The present invention relates to a slurry, a method for producing an electrode, and a method for producing a battery. [Background technology]

[0002] In response to growing environmental and energy issues, there has been active development of technologies aimed at realizing a low-carbon society that reduces dependence on fossil fuels. Such technological development is wide-ranging, and includes the development of low-pollution vehicles such as hybrid electric vehicles and electric vehicles, natural energy generation and storage systems such as solar and wind power generation, and next-generation power transmission networks that supply electricity efficiently and reduce transmission losses.

[0003] Batteries are one of the key devices required for these technologies. These batteries are required to have high energy density to miniaturize the systems. They also need high discharge rate characteristics to enable stable power supply regardless of the ambient temperature. Furthermore, they also need good cycle characteristics to withstand long-term use. Therefore, conventional lead-acid batteries, nickel-cadmium batteries, and nickel-metal hydride batteries are rapidly being replaced by lithium-ion secondary batteries, which have higher energy density, discharge rate characteristics, and cycle characteristics.

[0004] Conventionally, the positive electrode of a lithium-ion secondary battery is manufactured by coating a current collector with a positive electrode paste containing a positive electrode active material, a conductive material, and a binding material (also called a binder). Lithium-containing composite oxides such as lithium cobalt oxide and lithium manganese oxide have been used as the positive electrode active material. Furthermore, because the positive electrode active material has poor conductivity, a conductive material such as carbon black has been added to the positive electrode paste to impart conductivity (e.g., Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-227481 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, there has been a demand for further improvements in the performance of batteries such as lithium ion secondary batteries.

[0007] The present invention aims to provide a slurry containing carbon black that is useful for forming an electrode and a battery that has excellent discharge rate characteristics, cycle characteristics, and peel strength between a composite layer and a current collector. The present invention also aims to provide a method for manufacturing an electrode and a battery using the slurry. [Means for solving the problem]

[0008] The present invention relates to, for example, the following: <1> ~ <4> Regarding. <1> A slurry containing carbon black in a liquid medium, The carbon black has an average primary particle size of 17 nm or more and 30 nm or less, The carbon black has a crystallite size (Lc) of 15 Å or more and 26 Å or less, In the volume-based particle size distribution of the particle group including the secondary particles of carbon black in the slurry and the tertiary particles formed by agglomeration of the secondary particles of carbon black measured by a laser diffraction / scattering method, D50 (μm) is 0.5 μm or more and 0.9 μm or less, and the ratio of D50 (μm) to the difference between D10 (μm) and D90 (μm) (D50 / (D90-D10)) is 0.25 or more and 0.5 or less. <2> <1> 10. A coating liquid for forming an electrode, which is a mixture of the slurry according to 8. above, a binder solution containing a binder in a liquid medium, and an active material. <3> A method for manufacturing an electrode including a current collector and a composite layer, comprising: <1> 1. The slurry according to claim 1, a binder solution containing a binder in a liquid medium, and an active material are mixed together, <2> a coating liquid preparation step for obtaining the electrode-forming coating liquid described in a coating step of coating the electrode-forming coating liquid onto a current collector; an electrode formation step of removing at least a portion of the liquid medium to form a composite layer on the current collector, and forming an electrode including the current collector and the composite layer. <4> <3> A battery manufacturing method comprising the electrode manufacturing method described above. In this specification, the tilde symbol "~" may be used to indicate a range of values ​​including the values ​​before and after it. Specifically, the expression "X to Y" (where X and Y are both numbers) indicates "greater than or equal to X and less than or equal to Y." [Effects of the Invention]

[0009] The present invention provides a slurry useful for forming an electrode and a battery, which contains carbon black and has excellent discharge rate characteristics and cycle characteristics and excellent peel strength between a composite layer and a current collector. The present invention also provides a method for manufacturing an electrode and a battery using the slurry. DETAILED DESCRIPTION OF THE INVENTION

[0010] Preferred embodiments of the present invention will be described in detail below.

[0011] <Slurry> The slurry of this embodiment contains carbon black in a liquid medium. In this embodiment, the average primary particle diameter of the carbon black is 17 nm or more and 30 nm or less, and the crystallite size (Lc) of the carbon black is 15 Å or more and 26 Å or less. In addition, in the volume-based particle size distribution of the slurry of this embodiment measured by a laser diffraction / scattering method, D50 (μm) is 0.5 μm or more and 0.9 μm or less, and the ratio of D50 (μm) to the difference between D10 (μm) and D90 (μm) (D50 / (D90-D10)) is 0.25 or more and 0.5 or less.

[0012] The slurry of this embodiment is useful for forming electrodes for batteries such as lithium ion secondary batteries, and by using an electrode formed using the slurry of this embodiment, it is possible to form a battery with excellent discharge rate characteristics and cycle characteristics. In addition, it is possible to provide an electrode and a battery with excellent peel strength between the composite layer and the current collector.

[0013] According to the findings of the present inventors, by finely dispersing carbon black having an average primary particle size and crystallite size within the above ranges in a liquid medium so that the D50 and the ratio (D50 / (D90-D10)) fall within the above ranges, the carbon black in the slurry will be in a dispersed state effective for forming an electrode, and a battery with excellent discharge rate characteristics will be realized.

[0014] More specifically, in electrode formation, the structure of carbon black is thought to affect conductivity, and as the structure develops, conductive paths can be efficiently formed within the electrode. On the other hand, carbon black with a small primary particle size develops into a complexly entangled structure, which increases the viscosity of the slurry and makes it difficult to uniformly disperse the carbon black in the liquid medium. The slurry of this embodiment maintains a structure that allows for the formation of efficient conductive paths within the electrode, while finely dispersing the carbon black in the liquid medium in a dispersed state that is effective for electrode formation. Therefore, the slurry of this embodiment is thought to realize a battery with excellent discharge rate characteristics.

[0015] <Carbon black> In this embodiment, the carbon black may be acetylene black, furnace black, channel black, or the like, and is preferably acetylene black from the viewpoint of excellent purity and ease of obtaining excellent battery characteristics.

[0016] The average primary particle size of the carbon black is 17 nm or more, and may be 18 nm or more or 19 nm or more. It is believed that a large average primary particle size of the carbon black reduces the interaction between the liquid medium and the conductive material and the interaction between the conductive materials, making it easier to mix uniformly with the active material and form a strong conductive path, thereby making it easier to obtain excellent battery characteristics.

[0017] The carbon black has an average primary particle size of 30 nm or less, and may have an average primary particle size of 29 nm or less, 27 nm or less, 25 nm or less, 23 nm or less, or 21 nm or less. It is believed that a small average primary particle size of the carbon black increases the number of electrical contacts with the active material and the conductive material, improving conductivity and making it easier to obtain excellent battery characteristics. That is, the average primary particle diameter of the carbon black may be, for example, 17 to 30 nm, 17 to 29 nm, 17 to 27 nm, 17 to 25 nm, 17 to 23 nm, 17 to 21 nm, 18 to 30 nm, 18 to 29 nm, 18 to 27 nm, 18 to 25 nm, 18 to 23 nm, 18 to 21 nm, 19 to 30 nm, 19 to 29 nm, 19 to 27 nm, 19 to 25 nm, 19 to 23 nm, or 19 to 21 nm.

[0018] The average primary particle diameter of carbon black refers to the average value of the circle-equivalent diameters measured based on images of carbon black observed with a transmission electron microscope (TEM). Specifically, ten images of carbon black are taken at 100,000 magnifications using a transmission electron microscope JEM-2000FX (manufactured by JEOL Ltd.), and the circle-equivalent diameters of 200 primary particles of carbon black randomly selected from the obtained images are measured by image analysis, and the arithmetic mean is calculated.

[0019] The crystallite size (Lc) of the carbon black is 15 Å or more, and may be 16 Å or more. It is believed that a large crystallite size (Lc) of carbon black allows π electrons to move more easily in the crystal layer, making it easier to form conductive paths that carry electrons flowing from the current collector to the active material, thereby making it easier to obtain excellent battery characteristics.

[0020] The crystallite size (Lc) of the carbon black is 26 Å or less, and may be 25 Å or less, 23 Å or less, 21 Å or less, 19 Å or less, or 17 Å or less. When the crystallite size (Lc) of the carbon black is small, the particle shape of the primary particles of the carbon black tends to be more rounded, which is thought to reduce inter-particle interactions, facilitate uniform mixing with the active material, and facilitate the formation of conductive paths, making it easier to obtain excellent battery characteristics. That is, the crystallite size (Lc) of the carbon black may be, for example, 15 to 26 Å, 15 to 25 Å, 15 to 23 Å, 15 to 21 Å, 15 to 19 Å, 15 to 17 Å, 16 to 26 Å, 16 to 25 Å, 16 to 23 Å, 16 to 21 Å, 16 to 19 Å, or 16 to 17 Å.

[0021] The crystallite size (Lc) of carbon black is measured in accordance with JIS R 7651. The crystallite size (Lc) of carbon black means the crystallite size in the c-axis direction of the carbon black crystal layer.

[0022] The BET specific surface area of ​​carbon black is, for example, 100 m 2 / g or more, and 2 / g or more, 140m 2 / g or more, or 160m 2 When the BET specific surface area of ​​carbon black is large, there are more electrical contacts with the active material and the conductive material, and the conductivity is improved, which tends to make it easier to obtain better battery characteristics.

[0023] The BET specific surface area of ​​carbon black is, for example, 500 m 2 / g or less, and 2 / g or less, 400m 2 / g or less, 350m 2 / g or less, or 300m 2When the BET specific surface area of ​​carbon black is small, the interaction between the liquid medium and the conductive material and the interaction between the conductive materials are small, which makes it easier to mix the carbon black uniformly with the active material and makes it easier to form a strong conductive path, which tends to make it easier to obtain better battery characteristics. That is, the BET specific surface area of ​​carbon black is, for example, 100 to 500 m 2 / g, 100-450m 2 / g, 100-400m 2 / g, 100-350m 2 / g, 100-300m 2 / g, 120-500m 2 / g, 120-450m 2 / g, 120-400m 2 / g, 120-350m 2 / g, 120-300m 2 / g, 140-500m 2 / g, 140-450m 2 / g, 140-400m 2 / g, 140-350m 2 / g, 140-300m 2 / g, 160-500m 2 / g, 160-450m 2 / g, 160-400m 2 / g, 160-350m 2 / g or 160-300m 2 / g.

[0024] The BET specific surface area of ​​carbon black can be measured by the static capacitance method in accordance with JIS Z8830 using nitrogen as the adsorbate.

[0025] When the peak area of ​​the peak at mass number m / z 57 detected by thermal desorption spectroscopy of carbon black is defined as S1, and the peak area of ​​the peak at mass number m / z 128 is defined as S2, the ratio of the peak area S2 to the peak area S1 (S2 / S1) is preferably 0.2 to 1.9. The ratio (S2 / S1) indicates the proportion of organic components adsorbed to the surface of the carbon black. When the ratio (S2 / S1) is 1.9 or less, the amount of organic components adsorbed to the surface of the carbon black is sufficiently reduced, significantly suppressing the decrease in conductivity caused by the organic components trapping π electrons. Furthermore, when the ratio (S2 / S1) is 0.2 or more, the organic components adsorbed to the surface of the carbon black act as a dispersant, improving dispersibility in a liquid medium and further reducing the slurry viscosity. The peak area S1 of the peak with mass number m / z 57 and the peak area S2 of the peak with mass number m / z 128 can be measured by evolved gas mass spectrometry (EGA-MS). For example, carbon black is placed in a gas chromatograph mass spectrometer equipped with a pyrolysis device, and after being held at 50°C for 5 minutes in an atmospheric pressure He flow, the temperature is increased to 800°C at 80°C / min, and mass analysis is performed on the components desorbed by the temperature increase, thereby measuring the peak area S1 of the peak with mass number m / z 57 and the peak area S2 of the peak with mass number m / z 128.

[0026] From the viewpoint of more excellent discharge rate characteristics, the ratio (S2 / S1) may be 1.5 or less, 1.0 or less, 0.8 or less, 0.6 or less, 0.5 or less, 0.4 or less, or 0.3 or less, or may be 0.25 or more, or 0.3 or more. That is, the ratio (S2 / S1) may be, for example, 0.2 to 1.9, 0.2 to 1.5, 0.2 to 1.0, 0.2 to 0.8, 0.2 to 0.6, 0.2 to 0.5, 0.2 to 0.4, 0.2 to 0.3, 0.25 to 1.9, 0.25 to 1.5, 0.25 to 1.0, 0.25 to 0.8, 0.25 to 0.6, 0.25 to 0.5, 0.25 to 0.4, 0.25 to 0.3, 0.3 to 1.9, 0.3 to 1.5, 0.3 to 1.0, 0.3 to 0.8, 0.3 to 0.6, 0.3 to 0.5, or 0.3 to 0.4.

[0027] From the viewpoint of excellent conductivity, the volume resistivity of carbon black may be 0.30 Ω·cm or less or 0.25 Ω·cm or less. The volume resistivity of carbon black is measured, for example, in a compressed state under a load of 7.5 MPa.

[0028] The ash content and moisture content of the carbon black are not particularly limited. The ash content of the carbon black may be, for example, 0.04% by mass or less, and the moisture content of the carbon black may be, for example, 0.10% by mass or less.

[0029] The method for producing carbon black is not particularly limited. For example, the carbon black may be produced by a production method including a synthesis step of treating a raw material gas containing hydrocarbons in a cylindrical cracking furnace to obtain carbon black, and a purification step of removing magnetic foreign matter from the carbon black obtained in the synthesis step using a magnet.

[0030] In the synthesis step, the raw material gas is treated in a cylindrical cracking furnace. The cylindrical cracking furnace may include, for example, a pyrolysis section for carrying out a pyrolysis reaction of hydrocarbons and an aging section for modifying the pyrolysis reaction product. The cylindrical cracking furnace may further include a supply port for supplying the raw material gas to the pyrolysis section and a recovery port for recovering the carbon black produced from the aging section.

[0031] In the thermal decomposition section, the supplied raw material gas preferably resides at a temperature of 1900°C or higher for 30 to 150 seconds. A raw material gas residence time of 30 seconds or longer ensures the completion of the thermal decomposition reaction and the development of a chain structure to form a carbon aerosol. Furthermore, a raw material gas residence time of 150 seconds or shorter suppresses the aggregation of the carbon aerosol, making it easier to remove magnetic impurities in the purification step and to obtain high-purity carbon black.

[0032] In the aging section, the pyrolysis reaction product supplied from the pyrolysis section preferably resides at a temperature of 1700°C or higher for 20 to 90 seconds. A residence time of the pyrolysis reaction product of 20 seconds or longer modifies the carbon aerosol and promotes the growth of aggregates, making it easier to obtain higher quality carbon black. Furthermore, a residence time of the pyrolysis reaction product of 90 seconds or less suppresses the agglomeration of the carbon aerosol, making it easier to remove magnetic impurities in the purification step and to obtain high-purity carbon black.

[0033] The residence times in the thermal decomposition section and the aging section can be adjusted appropriately by adjusting the linear velocity of the gas flowing through them. The residence time in the aging section is preferably shorter than the residence time in the thermal decomposition section. That is, the linear velocity of the gas in the aging section is preferably higher than the linear velocity of the gas in the thermal decomposition section.

[0034] In this embodiment, the source gas preferably contains acetylene as a carbon source. The content of the carbon source (e.g., acetylene) in the source gas is, for example, 10% by volume or more, preferably 20% by volume or more, more preferably 30% by volume or more, and may be 100% by volume. The content of each component in the source gas is expressed as a volume ratio based on the volume at 100°C and 1 atmosphere.

[0035] The feed gas may further contain hydrocarbons other than the carbon source (e.g., acetylene). Examples of other hydrocarbons include methane, ethane, propane, ethylene, propylene, butadiene, benzene, toluene, xylene, gasoline, kerosene, light oil, and heavy oil. The addition of these other hydrocarbons can change the reaction temperature and increase or decrease the specific surface area of ​​the carbon black. The other hydrocarbons are preferably selected from the group consisting of aromatic hydrocarbons such as benzene and toluene, and unsaturated hydrocarbons such as ethylene and propylene.

[0036] When the raw material gas contains acetylene and other hydrocarbons, the content of the other hydrocarbons is, for example, 0.1 to 99 parts by volume, preferably 0.2 to 50 parts by volume, and more preferably 0.3 to 30 parts by volume relative to 100 parts by volume of acetylene. That is, the content of the other hydrocarbons may be, for example, 0.1 to 99 parts by volume, 0.1 to 50 parts by volume, 0.1 to 30 parts by volume, 0.2 to 99 parts by volume, 0.2 to 50 parts by volume, 0.2 to 30 parts by volume, 0.3 to 99 parts by volume, 0.3 to 50 parts by volume, or 0.3 to 30 parts by volume relative to 100 parts by volume of acetylene.

[0037] The raw material gas may further contain water vapor, oxygen, hydrogen, carbon dioxide, etc. These gases are preferably high-purity gases with a purity of 99.9% by volume or higher. The use of such high-purity gases tends to facilitate the production of carbon black with a low content of magnetic impurities and a stable BET specific surface area and oil absorption.

[0038] The content of the water vapor gas may be, for example, 0 to 80 parts by volume, preferably 0.1 to 70 parts by volume, more preferably 1 to 60 parts by volume, and even more preferably 3 to 55 parts by volume, relative to 100 parts by volume of the carbon source (e.g., acetylene) in the raw material gas. When the content of the water vapor gas is within the above range, the BET specific surface area of ​​the carbon black tends to be larger. That is, the content of the water vapor gas may be, for example, 0 to 80 parts by volume, 0 to 70 parts by volume, 0 to 60 parts by volume, 0 to 55 parts by volume, 0.1 to 80 parts by volume, 0.1 to 70 parts by volume, 0.1 to 60 parts by volume, 0.1 to 55 parts by volume, 1 to 80 parts by volume, 1 to 70 parts by volume, 1 to 60 parts by volume, 1 to 55 parts by volume, 3 to 80 parts by volume, 3 to 70 parts by volume, 3 to 60 parts by volume, or 3 to 55 parts by volume relative to 100 parts by volume of the carbon source (e.g., acetylene) in the raw material gas.

[0039] In the synthesis process, it is preferable to supply oxygen gas to the pyrolysis section together with the raw material gas, and it is more preferable to supply oxygen gas to the pyrolysis section by spraying it from around the supply port through which the raw material gas is supplied to the pyrolysis section.

[0040] The cylindrical cracking furnace preferably has an oxygen gas injection port near the raw material gas supply port, and more preferably has a plurality of injection ports provided at equal intervals so as to surround the supply port. The number of injection ports is preferably 3 or more, more preferably 3 to 8.

[0041] The cylindrical cracking furnace may also be equipped with a nozzle having a multi-tube structure (e.g., a double-tube structure, a triple-tube structure, etc.) having a raw material gas supply port and an injection port for injecting oxygen gas from the periphery thereof. In the case of a double-tube structure, for example, the raw material gas may be injected from a gap on the inner tube side, and the oxygen gas may be injected from a gap on the outer tube side. In the case of a triple-tube structure consisting of an inner tube, a middle tube, and an outer tube, for example, the oxygen gas may be injected from a gap formed by the outer wall of the middle tube and the inner wall of the outer tube, and the raw material gas may be injected from the remaining gap.

[0042] The amount of oxygen gas injected is not particularly limited as long as the production yield of carbon black is not taken into consideration. Carbon black can be produced even if more oxygen gas than necessary is injected. The amount of oxygen gas injected may be, for example, 0 to 300 parts by volume, 0 to 250 parts by volume, 0 to 220 parts by volume, or 0 to 200 parts by volume, per 100 parts by volume of the carbon source (e.g., acetylene) in the raw material gas, and is preferably 0.1 to 190 parts by volume, more preferably 0.5 to 180 parts by volume, and even more preferably 1 to 160 parts by volume. Increasing the amount of oxygen gas injected tends to increase the BET specific surface area of ​​the carbon black and the above ratio (S2 / S1), while decreasing the amount of oxygen gas injected tends to increase the average primary particle size of the carbon black. That is, the injection amount of oxygen gas is, for example, 0 to 300 parts by volume, 0 to 250 parts by volume, 0 to 220 parts by volume, 0 to 200 parts by volume, 0 to 190 parts by volume, 0 to 180 parts by volume, 0 to 160 parts by volume, 0.1 to 300 parts by volume, 0.1 to 250 parts by volume, 0.1 to 220 parts by volume, 0.1 to 200 parts by volume, 0.1 to 190 parts by volume, 0. It may be 1 to 180 parts by volume, 0.1 to 160 parts by volume, 0.5 to 300 parts by volume, 0.5 to 250 parts by volume, 0.5 to 220 parts by volume, 0.5 to 200 parts by volume, 0.5 to 190 parts by volume, 0.5 to 180 parts by volume, 0.5 to 160 parts by volume, 1 to 300 parts by volume, 1 to 250 parts by volume, 1 to 220 parts by volume, 1 to 200 parts by volume, 1 to 190 parts by volume, 1 to 180 parts by volume, or 1 to 160 parts by volume.

[0043] In the synthesis step, the average primary particle size, BET specific surface area, and crystallite size (Lc) of the resulting carbon black can be adjusted by, for example, adjusting the addition rate of hydrocarbons other than acetylene, the amount of oxygen gas to be injected, etc.

[0044] The purification step is a step of removing magnetic foreign matter from the carbon black obtained in the synthesis step using a magnet. The purification step may be, for example, a step of removing magnetic foreign matter from the carbon black obtained in the synthesis step by bringing the carbon black into contact with a magnet or placing it near a magnet (e.g., passing it near a magnet).

[0045] The maximum surface magnetic flux density of the magnet is not particularly limited, but may be, for example, 700 mT or more, preferably 1000 mT or more, and more preferably 1200 mT or more. This allows fine magnetic foreign matter adhering to the carbon black to be more strongly adsorbed, making it easier to obtain carbon black with a lower nickel content. The upper limit of the maximum surface magnetic flux density of the magnet is not particularly limited, and may be, for example, 1400 mT or less. That is, the maximum surface magnetic flux density of the magnet may be, for example, 700 to 1400 mT, 1000 to 1400 mT, or 1200 to 1400 mT.

[0046] The purification step may be a step of removing magnetic foreign matter from the carbon black so that the nickel content is 50 ppb or less (preferably 40 ppb or less, more preferably 30 ppb or less, and even more preferably 20 ppb or less). There is no particular lower limit for the nickel content, but the nickel content in the carbon black may be, for example, 1 ppb or more, and from the viewpoints of cost and productivity, it may be 10 ppb or more, or 15 ppb or more. That is, the nickel content in the carbon black may be, for example, 1 to 50 ppb, 1 to 40 ppb, 1 to 30 ppb, 1 to 20 ppb, 10 to 50 ppb, 10 to 40 ppb, 10 to 30 ppb, 10 to 20 ppb, 15 to 50 ppb, 15 to 40 ppb, 15 to 30 ppb, or 15 to 20 ppb.

[0047] <Liquid medium> The liquid medium is not particularly limited as long as it is a dispersion medium capable of finely dispersing carbon black. Examples of liquid media include water, N-methyl-2-pyrrolidone, cyclohexane, methyl ethyl ketone, and methyl isobutyl ketone. Among these, N-methyl-2-pyrrolidone is preferred from the viewpoint of easy dispersibility of carbon black. In this specification, N-methyl-2-pyrrolidone may be abbreviated as "NMP."

[0048] The carbon black content in the slurry of this embodiment may be, for example, 1% by mass or more, or may be 3% by mass or more, 5% by mass or more, or 10% by mass or more. A high carbon black content tends to make it easier to prepare an electrode-forming coating liquid with a high solids concentration. Furthermore, the carbon black content in the slurry of this embodiment may be, for example, 30% by mass or less, or may be 25% by mass or less, 20% by mass or less, or 15% by mass or less, based on the total amount of the slurry. A low carbon black content makes it easier to obtain an electrode-forming coating liquid with low viscosity, and makes it easier to obtain a uniform electrode when the electrode-forming coating liquid is applied. That is, the content of carbon black in the slurry of this embodiment may be, for example, 1 to 30 mass%, 1 to 25 mass%, 1 to 20 mass%, 1 to 15 mass%, 3 to 30 mass%, 3 to 25 mass%, 3 to 20 mass%, 3 to 15 mass%, 5 to 30 mass%, 5 to 25 mass%, 5 to 20 mass%, 5 to 15 mass%, 10 to 30 mass%, 10 to 25 mass%, 10 to 20 mass%, or 10 to 15 mass%.

[0049] <Dispersant> The slurry of this embodiment may further contain a dispersant, which may be any component that has the function of assisting the fine dispersion of carbon black in a liquid medium.

[0050] Examples of dispersants include polymeric dispersants and low molecular weight dispersants, and from the viewpoint of long-term dispersion stability of carbon black, polymeric dispersants are preferred.

[0051] The dispersant may be, for example, a dispersant selected from the group consisting of polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl butyral, carboxymethyl cellulose and its salts, polyvinyl acetal, polyvinyl acetate, polyvinylamine, and polyvinyl formal.

[0052] The content of the dispersant in the slurry of this embodiment may be, for example, 1 part by mass or more, or 3 parts by mass or more, 7 parts by mass or more, or 11 parts by mass or more, relative to 100 parts by mass of carbon black. A high content of dispersant tends to facilitate more uniform fine dispersion of the conductive material, making it easier to obtain better battery characteristics. Furthermore, the content of the dispersant in the slurry of this embodiment may be, for example, 50 parts by mass or less, or 30 parts by mass or less, 20 parts by mass or less, or 15 parts by mass or less, relative to 100 parts by mass of carbon black. A low content of dispersant tends to reduce the insulating components in the electrode-forming coating liquid, reducing the resistance of the electrode and making it easier to obtain better battery characteristics. That is, the content of the dispersant in the slurry of this embodiment may be, for example, 1 to 50 parts by mass, 1 to 30 parts by mass, 1 to 20 parts by mass, 1 to 15 parts by mass, 3 to 50 parts by mass, 3 to 30 parts by mass, 3 to 20 parts by mass, 3 to 15 parts by mass, 7 to 50 parts by mass, 7 to 30 parts by mass, 7 to 20 parts by mass, 7 to 15 parts by mass, 11 to 50 parts by mass, 11 to 30 parts by mass, 11 to 20 parts by mass, or 11 to 15 parts by mass relative to 100 parts by mass of carbon black.

[0053] <Particle size distribution of carbon black particles in slurry> The volume-based particle size distribution of the particle group, which is a combination of the secondary particles of carbon black and the tertiary particles formed by agglomeration of the secondary particles of carbon black in the slurry of this embodiment, is measured by a laser diffraction / scattering method, specifically under the following conditions. Measuring equipment: Laser diffraction / scattering particle size distribution measuring device (Microtrac Bell, model Microtrac MT3300EXII) Measurement conditions: Measurement range / 0.02 ~ 2000 μm, particle permeability / absorption, particle shape / non-spherical, solvent / NMP, circulation output / 5 Sample input amount: Add and adjust the amount of slurry so that the transmittance (TR) displayed when the sample is input is 0.85 to 0.9. The secondary particles of carbon black are particles generally called aggregates in the classification of carbon black structures, which are formed by chemically bonding primary particles of carbon black, and the tertiary particles of carbon black are particles generally called agglomerates.

[0054] In this specification, D10 means the particle size (10% diameter) (μm) at an integrated value of 10% in the particle size distribution, D50 means the particle size (50% diameter) (μm) at an integrated value of 50% in the particle size distribution, and D90 means the particle size (90% diameter) (μm) at an integrated value of 90% in the particle size distribution.

[0055] The D50 in the particle size distribution is 0.5 μm or more, or may be 0.6 μm or more, or 0.7 μm or more, and is 0.9 μm or less. That is, D50 in the particle size distribution may be, for example, 0.5 to 0.9 μm, 0.6 to 0.9 μm, or 0.7 to 0.9 μm.

[0056] The ratio of D50 to the difference between D10 and D90 in the particle size distribution (D50 / (D90-D10)) is 0.25 or more, and may be 0.26 or more, or 0.27 or more. The ratio of D50 to the difference between D10 and D90 in the particle size distribution (D50 / (D90-D10)) is 0.5 or less, and may be 0.48 or less, or 0.46 or less. That is, the ratio of D50 to the difference between D10 and D90 in the particle size distribution (D50 / (D90-D10)) may be, for example, 0.25 to 0.5, 0.25 to 0.48, 0.25 to 0.46, 0.26 to 0.5, 0.26 to 0.48, 0.26 to 0.46, 0.27 to 0.5, 0.27 to 0.48, or 0.27 to 0.46.

[0057] When the D50 and the ratio (D50 / (D90-D10)) in the slurry of this embodiment are within the above ranges, the carbon black can efficiently form a conductive path in the electrode, and the carbon black can be finely dispersed in a suitably dispersed state in the electrode-forming coating liquid described below.

[0058] In this embodiment, D50 and the ratio (D50 / (D90-D10)) can be adjusted by appropriately selecting the mixing method (for example, stirring means, stirring time, etc.) when forming the slurry.

[0059] <Other ingredients> The slurry of the present embodiment may further contain components other than the carbon black, dispersant, and liquid medium, such as carbon nanotubes, graphite, graphene, a binder, a dispersion stabilizer, and a defoaming agent.

[0060] The content of other components in the slurry of this embodiment may be, for example, 10% by mass or less, 5% by mass or less, 3% by mass or less, 1% by mass or less, 0.5% by mass or less, or 0.1% by mass or less, or may be 0% by mass.

[0061] <Slurry viscosity> The viscosity of the slurry of this embodiment at 25° C. and a shear rate of 10 (1 / sec) is preferably 100 to 1300 mPa·sec, for example, from the viewpoint of increasing the solids concentration of the electrode-forming coating liquid and facilitating the production of a uniform positive electrode.

[0062] <Method for producing slurry> The slurry of this embodiment can be produced by blending carbon black, a liquid medium, and, if necessary, a dispersant, and mixing / finely dispersing the carbon black in the liquid medium so that the secondary particles and tertiary particles exhibit the specified particle size distribution of the present invention.

[0063] The method of mixing / fine-dispersing is not particularly limited, and may be performed by a known method (for example, stirring and mixing using a bead mill, ball mill, sand mill, twin-screw kneader, planetary mixer, disperser mixer, etc.). These methods and devices may also be used in appropriate combination.

[0064] Various conditions in the mixing / fine-dispersing method may be appropriately adjusted so that D50 and the ratio (D50 / (D90-D10)) fall within the above-mentioned ranges. For example, by increasing the stirring time, D50 tends to decrease and the ratio (D50 / (D90-D10)) tends to increase. On the other hand, by decreasing the stirring time, D50 tends to increase and the ratio (D50 / (D90-D10)) tends to decrease.

[0065] <Electrode manufacturing method> The electrode manufacturing method of this embodiment includes a coating liquid preparation step of mixing a slurry, a binder solution containing a binder in a liquid medium, and an active material to obtain an electrode-forming coating liquid; a coating step of applying the electrode-forming coating liquid onto a current collector; and an electrode formation step of removing at least a portion of the liquid medium to form a composite layer on the current collector, thereby forming an electrode including the current collector and the composite layer.

[0066] <Binding solution> The binder solution is a solution containing a binder agent in a liquid medium.

[0067] The liquid medium in the binder solution may be the same as the liquid medium in the slurry. The liquid medium in the binder solution may be the same as or different from the liquid medium in the slurry, and is preferably the same as the liquid medium in the slurry.

[0068] Examples of the binder include polyvinylidene fluoride, polytetrafluoroethylene, styrene-butadiene copolymer, and (meth)acrylic acid ester copolymer. The polymer structure of the binder may be, for example, a random copolymer, an alternating copolymer, a graft copolymer, or a block copolymer. As the binder, polyvinylidene fluoride is preferred from the viewpoint of excellent voltage resistance.

[0069] The binder solution may further contain components other than the binder and the liquid medium, such as a conductive material, a thickener, and a surfactant.

[0070] The solid content concentration in the binder solution is not particularly limited and may be, for example, 1% by mass or more, 2% by mass or more, or 3% by mass or more. The solid content concentration in the binder solution may be, for example, 15% by mass or less, 13% by mass or less, or 10% by mass or less. That is, the solid content concentration in the binder solution may be, for example, 1 to 15 mass%, 1 to 13 mass%, 1 to 10 mass%, 2 to 15 mass%, 2 to 13 mass%, 2 to 10 mass%, 3 to 15 mass%, 3 to 13 mass%, or 3 to 10 mass%.

[0071] <Active material> The active material is not particularly limited, and for example, either a positive electrode active material or a negative electrode active material can be selected and used.

[0072] The type of the positive electrode active material is not particularly limited, and may be any material capable of reversibly absorbing and releasing cations. 4 The lithium-containing composite oxide containing manganese may have a resistivity of Ω·cm or more, or may be a lithium-containing polyanion compound. Examples of the lithium-containing composite oxide containing manganese include LiMnO2, LiMnO3, LiMn2O3, and Li 1+x Mn 2-x Lithium manganese oxide such as O4 (where x = 0 to 0.33); LiMn x Ni y Co z O2 (x+y+z=1, 0≦y<1, 0≦z<1, 0≦x<1), Li 1+x Mn 2-x-y M y O4 (where x = 0 to 0.33, y = 0 to 1.0, 2-xy>0), LiMn 2-x M x Examples of the lithium-containing polyanion compounds include polyanion compounds such as LiFePO4, LiMnPO4, and Li2MPO4F (where M is at least one metal selected from Co, Ni, Fe, Cr, and Zn). In each composition formula, M is at least one metal selected from the group consisting of Fe, Co, Ni, Al, Cu, Mg, Cr, Zn, and Ta.

[0073] The active material may be a negative electrode active material, such as a carbonaceous material including natural graphite, artificial graphite, graphite, activated carbon, coke, needle coke, fluid coke, mesophase microbeads, carbon fiber, and pyrolytic carbon.

[0074] <Coating liquid preparation process> The method for mixing the various components in the coating liquid preparation step is not particularly limited, and may be carried out by a known method (for example, stirring and mixing using a ball mill, sand mill, twin-screw kneader, planetary mixer, disper mixer, etc.).

[0075] The electrode-forming coating liquid contains the carbon black contained in the slurry, the binder contained in the binder solution, the active material, and the liquid medium contained independently in the slurry and the binder solution. The electrode-forming coating liquid may further contain a liquid medium (additional liquid medium) used in the coating liquid preparation step in addition to the liquid medium contained independently in the slurry and the binder solution. The electrode-forming coating liquid may further contain a dispersant.

[0076] The carbon black content in the electrode-forming coating liquid may be, for example, 0.01% by mass or more, 0.04% by mass or more, 0.07% by mass or more, or 0.1% by mass or more, based on the total amount of solids. The carbon black content in the electrode-forming coating liquid may be, for example, 8% by mass or less, 7% by mass or less, 6% by mass or less, or 5% by mass or less, based on the total amount of solids. That is, the content of carbon black in the electrode-forming coating liquid may be, for example, 0.01 to 8 mass%, 0.01 to 7 mass%, 0.01 to 6 mass%, 0.01 to 5 mass%, 0.04 to 8 mass%, 0.04 to 7 mass%, 0.04 to 6 mass%, 0.04 to 5 mass%, 0.07 to 8 mass%, 0.07 to 7 mass%, 0.07 to 6 mass%, 0.07 to 5 mass%, 0.1 to 8 mass%, 0.1 to 7 mass%, 0.1 to 6 mass%, or 0.1 to 5 mass%, based on the total amount of solids.

[0077] The content of the binder in the electrode-forming coating liquid may be, for example, 0.01% by mass or more, 0.02% by mass or more, 0.03% by mass or more, 0.04% by mass or more, or 0.05% by mass or more, based on the total amount of solids. The content of the binder in the electrode-forming coating liquid may be, for example, 10% by mass or less, 8% by mass or less, 6% by mass or less, or 4% by mass or less, based on the total amount of solids. That is, the content of the binder in the electrode-forming coating liquid may be, for example, 0.01 to 10 mass%, 0.01 to 8 mass%, 0.01 to 6 mass%, 0.01 to 4 mass%, 0.02 to 10 mass%, 0.02 to 8 mass%, 0.02 to 6 mass%, 0.02 to 4 mass%, 0.03 to 10 mass%, 0.03 to 8 mass%, 0.03 to 6 mass%, 0.03 to 4 mass%, 0.04 to 10 mass%, 0.04 to 8 mass%, 0.04 to 6 mass%, 0.04 to 4 mass%, 0.05 to 10 mass%, 0.05 to 8 mass%, 0.05 to 6 mass%, or 0.05 to 4 mass%, based on the total amount of solids.

[0078] The content of the active material in the electrode-forming coating liquid may be, for example, 70% by mass or more, 75% by mass or more, or 80% by mass or more, based on the total amount of solids. The content of the active material in the electrode-forming coating liquid may be, for example, 99% by mass or less, 98.9% by mass or less, or 98.8% by mass or less, based on the total amount of solids. That is, the content of the active material in the electrode-forming coating liquid may be, for example, 70 to 99 mass%, 70 to 98.9 mass%, 70 to 98.8 mass%, 75 to 99 mass%, 75 to 98.9 mass%, 75 to 98.8 mass%, 80 to 99 mass%, 80 to 98.9 mass%, or 80 to 98.8 mass%, based on the total amount of solids.

[0079] The content of the dispersant in the electrode-forming coating liquid may be, for example, 0.001% by mass or more, 0.004% by mass or more, 0.007% by mass or more, or 0.01% by mass or more, based on the total amount of solids. The content of the dispersant in the electrode-forming coating liquid may be, for example, 0.8% by mass or less, 0.7% by mass or less, 0.6% by mass or less, or 0.5% by mass or less, based on the total amount of solids. That is, the content of the dispersant in the electrode-forming coating liquid may be, for example, 0.001 to 0.8 mass%, 0.001 to 0.7 mass%, 0.001 to 0.6 mass%, 0.001 to 0.5 mass%, 0.004 to 0.8 mass%, 0.004 to 0.7 mass%, 0.004 to 0.6 mass%, 0.004 to 0.5 mass%, 0.007 to 0.8 mass%, 0.007 to 0.7 mass%, 0.007 to 0.6 mass%, 0.007 to 0.5 mass%, 0.01 to 0.8 mass%, 0.01 to 0.7 mass%, 0.01 to 0.6 mass%, or 0.01 to 0.5 mass%, based on the total amount of solids. The content of the dispersant in the electrode-forming coating liquid may be, for example, 1 part by mass or more, 3 parts by mass or more, 7 parts by mass or more, or 11 parts by mass or more, relative to 100 parts by mass of carbon black. The content of the dispersant in the electrode-forming coating liquid may be, for example, 50 parts by mass or less, 30 parts by mass or less, 20 parts by mass or less, or 15 parts by mass or less, relative to 100 parts by mass of carbon black. That is, the content of the dispersant in the electrode-forming coating liquid may be, for example, 1 to 50 parts by mass, 1 to 30 parts by mass, 1 to 20 parts by mass, 1 to 15 parts by mass, 3 to 50 parts by mass, 3 to 30 parts by mass, 3 to 20 parts by mass, 3 to 15 parts by mass, 7 to 50 parts by mass, 7 to 30 parts by mass, 7 to 20 parts by mass, 7 to 15 parts by mass, 11 to 50 parts by mass, 11 to 30 parts by mass, 11 to 20 parts by mass, or 11 to 15 parts by mass, relative to 100 parts by mass of carbon black.

[0080] The solids concentration of the electrode-forming coating liquid, i.e., the concentration of the carbon black and dispersant carried over from the slurry into the electrode-forming coating liquid, as well as the net binder and active material, may be, for example, 50% by mass or more, 55% by mass or more, 60% by mass or more, or 65% by mass or more. The solids concentration of the electrode-forming coating liquid may be, for example, 90% by mass or less, 85% by mass or less, 82% by mass or less, 77% by mass or less, 75% by mass or less, 73% by mass or less, or 70% by mass or less. That is, the solid content concentration of the coating liquid for forming an electrode is, for example, 50 to 90% by mass, 50 to 85% by mass, 50 to 82% by mass, 50 to 77% by mass, 50 to 75% by mass, or 50% by mass. ~73% by mass, 50-70% by mass, 55-90% by mass, 55-85% by mass, 55-82% by mass, 55-77% by mass, 55-75% by mass, 55-73% by mass, 5 5-70 mass%, 60-90 mass%, 60-85 mass%, 60-82 mass%, 60-77 mass%, 60-75 mass%, 60-73 mass%, 60-70 mass%, It may be 65-90% by mass, 65-85% by mass, 65-82% by mass, 65-77% by mass, 65-75% by mass, 65-73% by mass, or 65-70% by mass.

[0081] <Electrode formation process> In the electrode formation step, the electrode-forming coating liquid is applied onto a current collector to form a composite layer on the current collector. This results in an electrode including the current collector and the composite layer. The composite layer is a layer containing the solid components (carbon black, binder, and active material (and optionally a dispersant)) in the electrode-forming coating liquid, and may be a layer obtained by removing at least a portion of the liquid medium from the electrode-forming coating liquid.

[0082] The current collector is not particularly limited, and known current collectors can be used without any particular limitation. For example, metal foils (metals such as gold, silver, copper, platinum, aluminum, iron, nickel, chromium, manganese, lead, tungsten, and titanium, and alloys containing any one of these as the main component) are used as current collectors. Among these, it is preferable to use aluminum for the positive electrode and copper for the negative electrode. Current collectors are generally provided in the form of foils, but are not limited thereto, and perforated foil and mesh-shaped current collectors can also be used.

[0083] The method for applying the electrode-forming coating liquid onto the current collector is not particularly limited, and may be, for example, a die coating method, a dip coating method, a roll coating method, a doctor coating method, a knife coating method, a spray coating method, a gravure coating method, a screen printing method, or an electrostatic coating method.

[0084] The amount of the electrode-forming coating liquid to be applied is not particularly limited, and may be adjusted appropriately so that the thickness of the composite layer falls within a desired range.

[0085] The composite layer may be formed by removing at least a portion of the liquid medium from a coating film of the electrode-forming coating liquid formed on the current collector. The method for removing the liquid medium is not particularly limited, and examples thereof include methods for vaporizing and removing at least a portion of the liquid medium by heating and / or reducing pressure, such as leaving to dry, using a blower dryer, a hot air dryer, an infrared heater, and a far-infrared heater.

[0086] The electrode manufacturing method of the present embodiment may further include a pressurizing step of pressing the composite layer formed in the electrode formation step and the current collector in the stacking direction. The pressurizing step can bring the composite layer and the current collector into close contact with each other.

[0087] The pressing method in the pressing step is not particularly limited, and may be, for example, a roll press, a mold press, a calendar press, or the like.

[0088] The thickness of the composite layer in the electrode is not particularly limited and may be, for example, 50 μm or more, and from the viewpoint of increasing the capacity of the battery, it is preferably 55 μm or more, more preferably 60 μm or more, and may be 65 μm or more or 70 μm or more. Furthermore, the thickness of the composite layer in the electrode may be, for example, 150 μm or less, and from the viewpoint of further improving the discharge rate characteristics, it is preferably 140 μm or less, more preferably 130 μm or less, and may be 120 μm or less or 110 μm or less. That is, the thickness of the composite layer in the electrode may be, for example, 50 to 150 μm, 50 to 140 μm, 50 to 130 μm, 50 to 120 μm, 50 to 110 μm, 55 to 150 μm, 55 to 140 μm, 55 to 130 μm, 55 to 120 μm, 55 to 110 μm, 60 to 150 μm, 60 to 140 μm, 60 to 130 μm, 60 to 120 μm, 60 to 110 μm, 65 to 150 μm, 65 to 140 μm, 65 to 130 μm, 65 to 120 μm, 65 to 110 μm, 70 to 150 μm, 70 to 140 μm, 70 to 130 μm, 70 to 120 μm, or 70 to 110 μm.

[0089] The electrode manufactured by the manufacturing method of this embodiment can be suitably used as an electrode for a battery, particularly a secondary battery (lithium ion secondary battery).

[0090] The electrode of the present embodiment is an electrode including a composite layer containing carbon black, an active material, and a binder, and the composite layer may further contain a dispersant. The electrode of the present embodiment may be, for example, a positive electrode manufactured by the above-mentioned manufacturing method.

[0091] The battery (preferably a secondary battery, more preferably a lithium ion secondary battery) of this embodiment includes a positive electrode manufactured by the above-described manufacturing method. The configuration of the battery of this embodiment, other than the positive electrode, may be the same as that of a known battery.

[0092] The use of the battery in this embodiment is not particularly limited, and the battery can be used in a wide range of fields, for example, portable AV devices such as digital cameras, video cameras, portable audio players, and portable LCD televisions, portable information terminals such as notebook personal computers, smartphones, and mobile PCs, as well as portable game devices, power tools, electric bicycles, hybrid vehicles, electric vehicles, and power storage systems.

[0093] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. [Example]

[0094] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0095] Example 1 (Production of Carbon Black A) The raw material, acetylene, was injected at 12 Nm from a nozzle installed upstream of a carbon black reactor (furnace length 6 m, furnace diameter 0.65 m). 3 / h, toluene 32 kg / h, oxygen 20 Nm 3 / h to produce carbon black, which was then collected in a bag filter installed downstream of the reactor. The carbon black was then passed through a dry cyclone device and an iron-removing magnet before being collected in a tank. The acetylene, toluene, and oxygen were heated to 115°C before being supplied to the reactor, yielding carbon black A. The carbon black A thus obtained had an average primary particle size of 20 nm, a crystallite size (Lc) of 16 Å, and a BET specific surface area of ​​240 m. 2 / g.

[0096] Carbon black A was placed in an evolved gas mass spectrometer (GC / MS: Shimadzu QP-2010, pyrolyzer: Frontier Labs Py-2020iD) and held at 50°C for 5 minutes in an atmospheric pressure He flow, then heated to 800°C at 80°C / min. Mass analysis of the components desorbed by the temperature increase was performed under the following conditions, and the peak area S1 of the peak at mass number m / z 57 and the peak area S2 of the peak at mass number m / z 128 of the obtained carbon black A were measured. The ratio (S2 / S1) was calculated from the peak area S1 of the peak at mass number m / z 57 and the peak area S2 of the peak at mass number m / z 128 of the measured carbon black A, and was found to be 0.40. Column: Ultra ALLOY-D™ (2.5 m long, 0.15 mm I.D., 0.47 mm O.D.) manufactured by Frontier Labs Sample introduction temperature: 300℃ Column temperature: 300°C, maintained for 80 minutes Split ratio: 30:1 Column flow rate: 1.0 mL / min Ionization method: EI Measurement mass range: m / z = 10 to 200

[0097] (Slurry production) A carbon black-containing slurry was prepared by adding 1.4% by mass of polyvinyl alcohol (Poval B05, manufactured by Denka Co., Ltd., saponification degree: 87%) and 12.0% by mass of carbon black A as a dispersant to 86.6% by mass of NMP (liquid medium). The mixture was stirred at 70 rpm for 3 hours using a planetary mixer (Hibismix 3D-5, manufactured by Primix Corporation). The resulting slurry was dispersed for 54 minutes using a bead mill (Mugen Flow MGF2-ZA, manufactured by Ashizawa Finetech Co., Ltd.) equipped with zirconia beads (0.5 mm diameter) at a slurry flow rate of 1 kg / min and a mill peripheral speed of 8 m / s. After dispersion, the zirconia beads were removed by filtration to obtain the slurry of Example 1.

[0098] The volume-based particle size frequency distribution and cumulative distribution of the carbon black in the obtained slurry were measured using a laser diffraction / scattering particle size distribution analyzer (Microtrac MT3300EXII, manufactured by Microtrac Bell Corporation) according to the following method, and D10, D50, and D90 were calculated. Measurement conditions: Measurement range / 0.02 to 2000 μm, particle permeability / absorption, particle shape / non-spherical, solvent / NMP, circulation output / 5 Sample input amount: Slurry was added and adjusted to achieve the optimum concentration range displayed when the sample was input.

[0099] (Production of coating liquid for forming electrodes) The slurry obtained above, an NMP solution of polyvinylidene fluoride (binder), and a lithium nickel cobalt manganese composite oxide (LiNi 0.6 Mn 0.2 Co 0.2 Using O2 (positive electrode active material, manufactured by Beijing Dangsheng Co., Ltd., "ME6E") and NMP, the amount of NMP was adjusted so that the concentration of the solids, i.e., the carbon black and dispersant (1.0 part by mass) carried over from the slurry, plus the net binder (2.0 parts by mass) and positive electrode active material (97 parts by mass) (total 100 parts by mass), was 69% by mass of the entire electrode-forming coating liquid, thereby obtaining the electrode-forming coating liquid of Example 1.

[0100] (Cathode manufacturing) The obtained electrode-forming coating liquid was applied to a 15 μm-thick aluminum foil (manufactured by UACJ Corporation) using a Baker-type applicator, and dried at 105° C. for 1 hour to completely remove the NMP. Thereafter, the foil was pressed and cut to prepare a positive electrode.

[0101] (Manufacturing of negative electrodes) Pure water (Kanto Chemical Co., Ltd.) was used as the solvent, artificial graphite (Hitachi Chemical Co., Ltd., "MAG-D") was used as the negative electrode active material, styrene butadiene rubber (Zeon Corporation, "BM-400B", hereinafter referred to as SBR) was used as the binder, carboxymethyl cellulose (Daicel Corporation, "D2200", hereinafter referred to as CMC) was used as the dispersant, and carbon black (Denka Company, "Li-400") was used as the conductive material. Next, the CMC was weighed and mixed to a solid content of 1 mass %, carbon black was weighed and mixed to a solid content of 1 mass %, and artificial graphite was weighed and mixed to a solid content of 96 mass %, and pure water was added to this mixture. The mixture was mixed until homogeneous using a planetary centrifugal mixer (Thinky Corporation, Awatori Rentaro ARV-310) to obtain a mixture. Next, SBR was weighed out so that the solid content was 2% by mass, added to the resulting mixture, and mixed until uniform using a planetary mixer (Thinky Corporation, Awatori Rentaro ARV-310) to obtain a coating solution for forming a negative electrode. The coating solution for forming a negative electrode was then applied to a 10 μm-thick copper foil (UACJ Corporation) using an applicator to form a laminate, which was then placed in a dryer and pre-dried at 60 ° C for 1 hour. The laminate was then pressed using a roll press at a linear pressure of 50 kg / cm, and the overall thickness of the laminate was adjusted to 60 μm. The mixture was then vacuum dried at 120 ° C for 3 hours to completely remove residual moisture, obtaining a negative electrode comprising a current collector and a composite layer.

[0102] (battery manufacturing) The positive electrode, separator, and negative electrode were stacked and then packed with an aluminum laminate film and pre-sealed. Subsequently, an electrolyte was injected, and the battery was formatted and vacuum sealed to prepare a laminated secondary battery.

[0103] (Battery evaluation) The batteries in each of the examples and comparative examples demonstrating the effects of the present invention were evaluated using the same method as described in Example 1. With the exception of Table 4, it is appropriate to compare the results within the same table, where the same type of carbon black was used. [Discharge rate characteristics (rate capacity retention)] The fabricated batteries were charged at 25°C at a constant current and constant voltage of 4.3 V with a 0.2 C limit, and then discharged to 3.0 V at a constant current of 0.2 C. Next, they were again recovered charged at a constant current and constant voltage of 4.3 V with a 0.2 C limit, and then discharged to 3.0 V at a constant current of 0.2 C, and the discharge capacity was measured. Next, the recovery charge conditions were a constant current and constant voltage of 4.3 V with a 0.2 C limit, while the discharge current was gradually changed to 0.5 C, 1 C, 2 C, and 3 C. Recovery charge and discharge were repeated, and the discharge capacity for each discharge current was measured. The rate capacity retention ratio was calculated as the capacity retention ratio at 3 C discharge relative to 0.2 C discharge as an index of the battery's discharge rate characteristics.

[0104] [Cycle characteristics (cycle capacity retention rate)] The fabricated battery was charged at 25°C at a constant current and constant voltage of 4.3 V (1 C), and then discharged to 3.0 V at a constant current of 1 C. The above charge / discharge cycle was repeated 500 times, and the discharge capacity at each cycle was measured. As an index of the battery's cycle characteristics, the capacity retention rate after 500 cycles relative to the capacity retention rate after 1 cycle was calculated as the cycle capacity retention rate.

[0105] [Peel strength] The electrode-forming coating liquid was applied onto an aluminum foil (manufactured by UACJ Corporation) having a thickness of 15 μm using a Baker-type applicator, and dried at 105° C. for 1 hour to completely remove the NMP. The resulting positive electrode was then pressed and cut, and subjected to a 180°C peel test using a peel strength tester (Shimadzu Corporation, AGS-X). 2 , density 3.4mg / cm 3The peel strength between the aluminum foil and the electrode composite was measured under the conditions of a test piece width of 2 cm and a pulling speed of 50 mm / min. The average test force (N) for the stroke width of the peeled electrode plate in the range of 30 to 70 mm was calculated as the peel strength.

[0106] <Example 2> (Slurry production) A carbon black-containing slurry was prepared by adding 1.4% by mass of polyvinyl alcohol (Poval B05, manufactured by Denka Co., Ltd., saponification degree: 87%) as a dispersant and 12.0% by mass of carbon black A to 86.6% by mass of NMP and stirring at 70 rpm for 3 hours using a planetary mixer (Hibismix 3D-5, manufactured by Primix Corporation). The resulting slurry was dispersed for 60 minutes using a bead mill (Mugen Flow MGF2-ZA, manufactured by Ashizawa Finetech Co., Ltd.) equipped with zirconia beads (diameter 0.5 mm) at a slurry flow rate of 1 kg / min and a mill peripheral speed of 8 m / s. After dispersion, the zirconia beads were removed by filtration to obtain the slurry of Example 2. Using this slurry, an electrode-forming coating liquid, a positive electrode, a negative electrode, and a battery were produced in the same manner as in Example 1, and each evaluation was carried out.

[0107] Example 3 (Slurry production) A carbon black-containing slurry was prepared by adding 1.4% by mass of polyvinyl alcohol (Poval B05, manufactured by Denka Co., Ltd., saponification degree: 87%) as a dispersant and 12.0% by mass of carbon black A to 86.6% by mass of NMP and stirring at 70 rpm for 3 hours using a planetary mixer (Hibismix 3D-5, manufactured by Primix Corporation). The resulting slurry was dispersed for 45 minutes using a bead mill (Mugen Flow MGF2-ZA, manufactured by Ashizawa Finetech Co., Ltd.) equipped with zirconia beads (0.5 mm diameter) at a slurry flow rate of 1 kg / min and a mill peripheral speed of 8 m / s. After dispersion, the zirconia beads were removed by filtration to produce the slurry of Example 3. Using this slurry, an electrode-forming coating liquid, a positive electrode, a negative electrode, and a battery were produced in the same manner as in Example 1, and each evaluation was carried out.

[0108] <Comparative Example 1> (Slurry production) A carbon black-containing slurry was prepared by adding 1.4% by mass of polyvinyl alcohol (Poval B05, manufactured by Denka Co., Ltd., saponification degree: 87%) as a dispersant and 12.0% by mass of carbon black A to 86.6% by mass of NMP and stirring at 70 rpm for 3 hours using a planetary mixer (Hibismix 3D-5, manufactured by Primix Corporation). The resulting slurry was dispersed for 18 minutes using a bead mill (Mugen Flow MGF2-ZA, manufactured by Ashizawa Finetech Co., Ltd.) equipped with zirconia beads (0.5 mm diameter) at a slurry flow rate of 1 kg / min and a mill peripheral speed of 8 m / s. After dispersion, the zirconia beads were removed by filtration to produce the slurry of Comparative Example 1. Using this slurry, an electrode-forming coating liquid, a positive electrode, a negative electrode, and a battery were produced in the same manner as in Example 1, and each evaluation was carried out.

[0109] <Comparative Example 2> (Slurry production) A carbon black-containing slurry was prepared by adding 1.4% by mass of polyvinyl alcohol (Poval B05, manufactured by Denka Co., Ltd., saponification degree: 87%) as a dispersant and 12.0% by mass of carbon black A to 86.6% by mass of NMP and stirring at 70 rpm for 3 hours using a planetary mixer (Hibismix 3D-5, manufactured by Primix Corporation). The resulting slurry was dispersed for 198 minutes using a bead mill (Mugen Flow MGF2-ZA, manufactured by Ashizawa Finetech Co., Ltd.) equipped with zirconia beads (diameter 0.5 mm) at a slurry flow rate of 1 kg / min and a mill peripheral speed of 8 m / s. After dispersion, the zirconia beads were removed by filtration to prepare the slurry of Comparative Example 2. Using this slurry, an electrode-forming coating liquid, a positive electrode, a negative electrode, and a battery were produced in the same manner as in Example 1, and each evaluation was carried out.

[0110] The evaluation results of Examples 1 to 3 and Comparative Examples 1 and 2 are shown in Table 1. In the table, CB represents carbon black, and CBA represents carbon black A. The same applies to the following tables.

[0111] [Table 1]

[0112] Example 4 (Production of coating liquid for forming electrodes) The slurry of Example 3, an NMP solution of polyvinylidene fluoride (binder), and a lithium nickel cobalt manganese composite oxide LiNi 0.6 Mn 0.2 Co 0.2 O2 (positive electrode active material, manufactured by Beijing Dangsheng Co., Ltd., "ME6E") and NMP were mixed to a solids concentration of 69.5 mass% with 1.0 mass part of carbon black, 1.3 mass parts of binder, and 97.7 mass parts of positive electrode active material, to obtain an electrode-forming coating liquid. Using the obtained electrode-forming coating liquid, a positive electrode, a negative electrode and a battery were produced in the same manner as in Example 1, and each evaluation was carried out.

[0113] <Example 5> (Production of coating liquid for forming electrodes) The slurry of Example 3, an NMP solution of polyvinylidene fluoride (binder), and a lithium nickel cobalt manganese composite oxide LiNi 0.6 Mn 0.2 Co 0.2 O2 (positive electrode active material, manufactured by Beijing Dangsheng Co., Ltd., "ME6E") and NMP were mixed to obtain a coating liquid for forming an electrode, with 1.0 part by mass of carbon black, 2.5 parts by mass of binder, and 96.5 parts by mass of positive electrode active material, for a solids concentration of 64.5% by mass. Using the obtained electrode-forming coating liquid, a positive electrode, a negative electrode and a battery were produced in the same manner as in Example 1, and each evaluation was carried out.

[0114] <Comparative Example 3> (Production of coating liquid for forming electrodes) The slurry of Comparative Example 1, an NMP solution of polyvinylidene fluoride (binder), and a lithium nickel cobalt manganese composite oxide LiNi 0.6 Mn 0.2 Co 0.2 O2 (positive electrode active material, manufactured by Beijing Dangsheng Co., Ltd., "ME6E") and NMP were mixed to a solids concentration of 69.5 mass% with 1.0 mass part of carbon black, 1.3 mass parts of binder, and 97.7 mass parts of positive electrode active material, to obtain an electrode-forming coating liquid. Using the obtained electrode-forming coating liquid, a positive electrode, a negative electrode and a battery were produced in the same manner as in Example 1, and each evaluation was carried out.

[0115] <Comparative Example 4> (Production of coating liquid for forming electrodes) The slurry of Comparative Example 1, an NMP solution of polyvinylidene fluoride (binder), and a lithium nickel cobalt manganese composite oxide LiNi 0.6 Mn 0.2 Co 0.2 O2 (positive electrode active material, manufactured by Beijing Dangsheng Co., Ltd., "ME6E") and NMP were mixed to obtain a coating liquid for forming an electrode, with 1.0 part by mass of carbon black, 2.5 parts by mass of binder, and 96.5 parts by mass of positive electrode active material, for a solids concentration of 64.5% by mass. Using the obtained electrode-forming coating liquid, a positive electrode, a negative electrode and a battery were produced in the same manner as in Example 1, and each evaluation was carried out.

[0116] Table 2 shows the evaluation results of Examples 4 to 5 and Comparative Examples 3 to 4.

[0117] [Table 2]

[0118] Example 6 (Slurry production) The mixture was 85.6% by mass of NMP, and 0.9% by mass of polyvinyl alcohol (Poval DR-1137 manufactured by Denka Co., Ltd., saponification degree: 87%) and carbon black (Li-435 manufactured by Denka Co., Ltd., average primary particle diameter: 26 nm, crystallite size (Lc): 25 Å, BET specific surface area: 133 m) were added as dispersants.2 A carbon black-containing slurry was prepared by adding 13.5% by mass of ... Using this slurry, an electrode-forming coating liquid, a positive electrode, a negative electrode, and a battery were produced in the same manner as in Example 1, and each evaluation was carried out.

[0119] Example 7 (Slurry production) A carbon black-containing slurry was prepared by adding 0.9% by mass of polyvinyl alcohol (Poval DR-1137, manufactured by Denka Co., Ltd., saponification degree: 87%) as a dispersant and 13.5% by mass of carbon black (Li-435, manufactured by Denka Co., Ltd.) to 85.6% by mass of NMP and stirring at 70 rpm for 3 hours using a planetary mixer (Hibismix 3D-5, manufactured by Primix Corporation). The resulting slurry was dispersed for 50 minutes using a bead mill (Mugen Flow MGF2-ZA, manufactured by Ashizawa Finetech Co., Ltd.) equipped with zirconia beads (0.5 mm diameter) at a slurry flow rate of 1 kg / min and a mill peripheral speed of 8 m / s. After dispersion, the zirconia beads were removed by filtration to produce the slurry of Example 7. Using this slurry, an electrode-forming coating liquid, a positive electrode, a negative electrode, and a battery were produced in the same manner as in Example 1, and each evaluation was carried out.

[0120] Example 8 (Slurry production) A carbon black-containing slurry was prepared by adding 0.9% by mass of polyvinyl alcohol (Poval DR-1137, manufactured by Denka Co., Ltd., saponification degree: 87%) as a dispersant and 13.5% by mass of carbon black (Li-435, manufactured by Denka Co., Ltd.) to 85.6% by mass of NMP and stirring at 70 rpm for 3 hours using a planetary mixer (Hibismix 3D-5, manufactured by Primix Corporation). The resulting slurry was dispersed for 36 minutes using a bead mill (Mugen Flow MGF2-ZA, manufactured by Ashizawa Finetech Co., Ltd.) equipped with zirconia beads (0.5 mm diameter) at a slurry flow rate of 1 kg / min and a mill peripheral speed of 8 m / s. After dispersion, the zirconia beads were removed by filtration to produce the slurry of Example 8. Using this slurry, an electrode-forming coating liquid, a positive electrode, a negative electrode, and a battery were produced in the same manner as in Example 1, and each evaluation was carried out.

[0121] <Comparative Example 5> (Slurry production) A carbon black-containing slurry was prepared by adding 0.9% by mass of polyvinyl alcohol (Poval DR-1137, manufactured by Denka Co., Ltd., saponification degree: 87%) as a dispersant and 13.5% by mass of carbon black (Li-435, manufactured by Denka Co., Ltd.) to 85.6% by mass of NMP and stirring at 70 rpm for 3 hours using a planetary mixer (Hibismix 3D-5, manufactured by Primix Corporation). The resulting slurry was dispersed for 8 minutes using a bead mill (Mugen Flow MGF2-ZA, manufactured by Ashizawa Finetech Co., Ltd.) equipped with zirconia beads (0.5 mm diameter) at a slurry flow rate of 1 kg / min and a mill peripheral speed of 8 m / s. After dispersion, the zirconia beads were removed by filtration to produce the slurry of Comparative Example 5. Using this slurry, an electrode-forming coating liquid, a positive electrode, a negative electrode, and a battery were produced in the same manner as in Example 1, and each evaluation was carried out.

[0122] <Comparative Example 6> (Slurry production) A carbon black-containing slurry was prepared by adding 0.9% by mass of polyvinyl alcohol (Poval DR-1137, manufactured by Denka Co., Ltd., saponification degree: 87%) as a dispersant and 13.5% by mass of carbon black (Li-435, manufactured by Denka Co., Ltd.) to 85.6% by mass of NMP and stirring at 70 rpm for 3 hours using a planetary mixer (Hibismix 3D-5, manufactured by Primix Corporation). The resulting slurry was dispersed for 154 minutes using a bead mill (Mugen Flow MGF2-ZA, manufactured by Ashizawa Finetech Co., Ltd.) equipped with zirconia beads (0.5 mm diameter) at a slurry flow rate of 1 kg / min and a mill peripheral speed of 8 m / s. After dispersion, the zirconia beads were removed by filtration to produce the slurry of Comparative Example 6. Using this slurry, an electrode-forming coating liquid, a positive electrode, a negative electrode, and a battery were produced in the same manner as in Example 1, and each evaluation was carried out.

[0123] Table 3 shows the evaluation results of Examples 6 to 8 and Comparative Examples 5 and 6.

[0124] [Table 3]

[0125] <Comparative Example 7> (Slurry production) The mixture was 89.7% by mass of NMP, 1.3% by mass of polyvinyl alcohol (Poval DR-1137 manufactured by Denka Co., Ltd., saponification degree: 87%) as a dispersant, and 1.3% by mass of carbon black (BLACK PEARLS 1000 manufactured by Cabot Corporation, average primary particle diameter: 16 nm, crystallite size (Lc): 14 Å, BET specific surface area: 343 m 2A carbon black-containing slurry was prepared by adding 9.0% by mass of 100% ammonium hydroxide (S2 / S1) (ratio (S2 / S1): 3.42) to the mixture and stirring at 70 rpm for 3 hours using a planetary mixer (Hibismix 3D-5, manufactured by Primix Corporation). The resulting slurry was dispersed for 45 minutes using a bead mill (Mugen Flow MGF2-ZA, manufactured by Ashizawa Finetech Co., Ltd.) equipped with zirconia beads (0.5 mm diameter) at a slurry flow rate of 1 kg / min and a mill peripheral speed of 8 m / s. After dispersion, the zirconia beads were removed by filtration to produce the slurry of Comparative Example 7. Using this slurry, an electrode-forming coating liquid, a positive electrode, a negative electrode, and a battery were produced in the same manner as in Example 1, and each evaluation was carried out.

[0126] <Comparative Example 8> (Slurry production) The mixture was 87.6% by mass of NMP, and 1.7% by mass of polyvinyl alcohol (Poval DR-1137 manufactured by Denka Co., Ltd., saponification degree: 87%) and carbon black (ECP manufactured by Lion Corporation, average primary particle diameter: 40 nm, crystallite size (Lc): 16 Å, BET specific surface area: 820 m) were added as dispersants. 2 A carbon black-containing slurry was prepared by adding 10.7% by mass of 10.7% S2 / S1 (S2 / S1 ratio: 2.06) to the mixture and stirring at 70 rpm for 3 hours using a planetary mixer (Hibismix 3D-5, manufactured by Primix Corporation). The resulting slurry was dispersed for 55 minutes using a bead mill (Mugen Flow MGF2-ZA, manufactured by Ashizawa Finetech Co., Ltd.) equipped with zirconia beads (0.5 mm diameter) at a slurry flow rate of 1 kg / min and a mill peripheral speed of 8 m / s. After dispersion, the zirconia beads were removed by filtration to produce the slurry of Comparative Example 8. Using this slurry, an electrode-forming coating liquid, a positive electrode, a negative electrode, and a battery were produced in the same manner as in Example 1, and each evaluation was carried out.

[0127] <Comparative Example 9> (Slurry production) The mixture was 80.7% by mass of NMP, 1.3% by mass of polyvinyl alcohol (Poval DR-1137 manufactured by Denka Co., Ltd., saponification degree: 87%) as a dispersant, and carbon black (SuperPLi manufactured by Imerys Graphite & Carbon Co., Ltd., average primary particle diameter: 36 nm, crystallite size (Lc): 20 Å, BET specific surface area: 62 m 2 A carbon black-containing slurry was prepared by adding 18.0% by mass of 18.0% S2 / g (S2 / S1 ratio: 1.12) and stirring at 70 rpm for 3 hours using a planetary mixer (Hibismix 3D-5, manufactured by Primix Corporation). The resulting slurry was dispersed for 20 minutes using a bead mill (Mugen Flow MGF2-ZA, manufactured by Ashizawa Finetech Co., Ltd.) equipped with zirconia beads (0.5 mm diameter) at a slurry flow rate of 1 kg / min and a mill peripheral speed of 8 m / s. After dispersion, the zirconia beads were removed by filtration to produce the slurry of Comparative Example 9. Using this slurry, an electrode-forming coating liquid, a positive electrode, a negative electrode, and a battery were produced in the same manner as in Example 1, and each evaluation was carried out.

[0128] <Comparative Example 10> (Slurry production) The mixture was 83.5% by mass of NMP, and 1.5% by mass of polyvinyl alcohol (Poval DR-1137 manufactured by Denka Co., Ltd., saponification degree: 87%) and carbon black (YS manufactured by Orion Co., Ltd., average primary particle diameter: 26 nm, crystallite size (Lc): 27 Å, BET specific surface area: 120 m) were added as dispersants. 2 A carbon black-containing slurry was prepared by adding 15.0% by mass of 15.0% S2 / g (S2 / S1 ratio: 0.92) and stirring at 70 rpm for 3 hours using a planetary mixer (Hibismix 3D-5, manufactured by Primix Corporation). The resulting slurry was dispersed for 35 minutes using a bead mill (Mugen Flow MGF2-ZA, manufactured by Ashizawa Finetech Co., Ltd.) equipped with zirconia beads (0.5 mm diameter) at a slurry flow rate of 1 kg / min and a mill peripheral speed of 8 m / s. After dispersion, the zirconia beads were removed by filtration to produce the slurry of Comparative Example 10. Using this slurry, an electrode-forming coating liquid, a positive electrode, a negative electrode, and a battery were produced in the same manner as in Example 1, and each evaluation was carried out.

[0129] Table 4 shows the evaluation results of Comparative Examples 7 to 10.

[0130] [Table 4]

Claims

1. A slurry containing carbon black in a liquid medium, the average primary particle diameter of the carbon black is 17 nm or more and 25 nm or less; The crystallite size (Lc) of the carbon black is 15 Å or more and 23 Å or less, The carbon black has a BET specific surface area of ​​140 m 2 / g or more; In the volume-based particle size distribution of a particle group including secondary particles of carbon black and tertiary particles formed by agglomeration of the secondary particles of carbon black in the slurry, as measured by a laser diffraction / scattering method, D50 (μm) is 0.5 μm or more and 0.9 μm or less, and the ratio of D50 (μm) to the difference between D10 (μm) and D90 (μm) (D50 / (D90-D10)) is 0.25 or more and 0.5 or less.

2. A coating liquid for forming an electrode, which is a mixture of the slurry according to claim 1, a binder solution containing a binder in a liquid medium, and an active material.

3. A method for manufacturing an electrode including a current collector and a composite layer, comprising: a coating liquid preparation step of mixing the slurry according to claim 1, a binder solution containing a binder in a liquid medium, and an active material to obtain the electrode-forming coating liquid according to claim 2; a coating step of coating the electrode-forming coating liquid onto a current collector; an electrode formation step of removing at least a portion of the liquid medium to form a composite layer on the current collector, and forming an electrode including the current collector and the composite layer.

4. A method for manufacturing a battery, comprising the method for manufacturing an electrode according to claim 3 .

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