JP6778385B2 - Conductive material for lithium ion secondary battery, composition for forming negative electrode of lithium ion secondary battery, composition for forming positive electrode of lithium ion secondary battery, negative electrode for lithium ion secondary battery, positive electrode for lithium ion secondary battery and lithium ion secondary Next battery - Google Patents

Description

The present invention relates to a conductive material for a lithium ion secondary battery, a composition for forming a negative electrode of a lithium ion secondary battery, a composition for forming a positive electrode of a lithium ion secondary battery, a negative electrode for a lithium ion secondary battery, a positive electrode for a lithium ion secondary battery, and the like. Regarding lithium ion secondary batteries.

Lithium-ion secondary batteries are lighter than other secondary batteries such as nickel-metal hydride batteries and lead-acid batteries, and have high input / output characteristics. Therefore, in recent years, high-load batteries used in electric vehicles, hybrid electric vehicles, etc. It is attracting attention as an output power supply.

The electrodes of the lithium ion secondary battery include a positive electrode in which a lithium compound containing Fe or Mn as a metal element as a constituent element is used as a positive electrode active material, and a negative electrode in which a carbon material capable of occluding and releasing lithium ions is used as a negative electrode active material. , Is used. In order to improve the conductivity of the positive electrode active material in the positive electrode or the charge / discharge characteristics in the negative electrode, a carbon material such as carbon black (for example, acetylene black) is added to the positive electrode material or the negative electrode material as a conductive auxiliary agent. Is known (see, for example, Patent Document 1).

On the other hand, if impurities (magnetic impurities such as Fe, Ni, and Cu) are present in the constituent materials of the battery, the impurities may be deposited on the negative electrode during charging and discharging. Impurities deposited on the negative electrode can cause a short circuit by breaking the separator and reaching the positive electrode. In addition, the lithium ion secondary battery may be used in a car or the like in summer. In this case, the operating temperature of the lithium ion secondary battery may be 40 ° C to 80 ° C. At this time, the metal in the Li-containing metal oxide constituting the positive electrode may elute from the positive electrode, and the characteristics of the battery may deteriorate.
Therefore, a scavenger or an adsorbent for impurities (hereinafter, simply referred to as an adsorbent) and a stabilization of the positive electrode have been studied (see, for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 2011-181229 Japanese Unexamined Patent Publication No. 2000-77103

As the demand for the characteristics of lithium-ion secondary batteries increases, the demand for both electrical characteristics and life characteristics of lithium-ion secondary batteries is increasing. Therefore, according to the present invention, a conductive material for a lithium ion secondary battery capable of imparting excellent electrical characteristics and life characteristics of a lithium ion secondary battery, and a negative electrode formation for a lithium ion secondary battery using the conductive material for the lithium ion secondary battery. It is an object of the present invention to provide a composition for forming a positive electrode of a lithium ion secondary battery, a negative electrode for a lithium ion secondary battery, a positive electrode for a lithium ion secondary battery, and a lithium ion secondary battery.

The present invention is as follows.
<1> Magnesium aluminum oxide and
The carbon arranged on the surface of the magnesium aluminum oxide and
A conductive material for a lithium ion secondary battery containing a magnesium-aluminum oxide composite having.

<2> The conductive material for a lithium ion secondary battery according to <1>, wherein the carbon content ratio in the magnesium-aluminum oxide composite is 0.1% by mass to 50% by mass.

<3> The conductive material for a lithium ion secondary battery according to <1> or <2>, wherein the R value obtained from the Raman spectrum analysis of the magnesium aluminum oxide composite is 0.1 to 5.0.

<4> The lithium ion secondary battery according to any one of <1> to <3>, wherein the magnesium aluminum oxide composite has a powder resistivity of 0.001 Ω · cm to 100 Ω · cm. Conductive material.

<5> For forming a negative electrode of a lithium ion secondary battery containing the conductive material for a lithium ion secondary battery according to any one of <1> to <4>, a negative electrode active material, and a binder. Composition.

<6> For forming a positive electrode of a lithium ion secondary battery containing the conductive material for a lithium ion secondary battery according to any one of <1> to <4>, a positive electrode active material, and a binder. Composition.

<7> With the current collector
A negative electrode layer provided on the current collector and containing the conductive material for a lithium ion secondary battery and the negative electrode active material according to any one of <1> to <4>.
Negative electrode for lithium ion secondary batteries.

<8> With the current collector
A positive electrode layer provided on the current collector and containing the conductive material for a lithium ion secondary battery and the positive electrode active material according to any one of <1> to <4>.
Positive electrode for lithium ion secondary battery.

<9> A lithium ion secondary battery including at least one of the negative electrode for a lithium ion secondary battery according to <7> and the positive electrode for a lithium ion secondary battery according to <8>.

According to the present invention, a conductive material for a lithium ion secondary battery which can impart excellent electrical characteristics and life characteristics of a lithium ion secondary battery, and a negative electrode of a lithium ion secondary battery using a conductive material for a lithium ion secondary battery. A composition for forming, a composition for forming a positive electrode of a lithium ion secondary battery, a negative electrode for a lithium ion secondary battery, a positive electrode for a lithium ion secondary battery, and a lithium ion secondary battery can be provided.

It is the schematic sectional drawing which shows an example of the structure of the magnesium aluminum oxide composite. It is the schematic sectional drawing which shows an example of the structure of the magnesium aluminum oxide composite. It is the schematic sectional drawing which shows an example of the structure of the magnesium aluminum oxide composite. It is the schematic sectional drawing which shows an example of the structure of the magnesium aluminum oxide composite. It is the schematic sectional drawing which shows an example of the structure of the magnesium aluminum oxide composite.

In the present specification, the term "process" is included in this term not only as an independent process but also as long as the intended purpose of the process is achieved even if it cannot be clearly distinguished from other processes. .. Further, the numerical range indicated by using "-" in the present specification indicates a range including the numerical values before and after "-" as the minimum value and the maximum value, respectively. Further, in the present specification, the amount of each component in the composition is the total amount of the plurality of substances present in the composition unless otherwise specified, when a plurality of substances corresponding to each component are present in the composition. means.

The conductive material for a lithium ion secondary battery of the present invention includes a magnesium aluminum oxide composite having a magnesium aluminum oxide and carbon arranged on the surface of the magnesium aluminum oxide. The conductive material for a lithium ion secondary battery of the present invention has the above configuration, so that the electrical characteristics and life characteristics of the lithium ion secondary battery can be improved.

The magnesium aluminum oxide contained in the conductive material for a lithium ion secondary battery is an oxide salt containing magnesium (Mg) and aluminum (Al). The oxide salt of Mg and Al has many OH groups, which have ion exchange ability. As a result, the magnesium-aluminum oxide has many metal ion adsorption sites per unit mass, and highly selectively adsorbs metal ions with a high specific surface area. The magnesium-aluminum oxide composite is particularly susceptible to adsorbing transition metal ions such as nickel ions, manganese ions, cobalt ions, copper ions and iron ions rather than alkali metal ions such as lithium ions and sodium ions. Tends to show properties.

The magnesium-aluminum oxide composite in the present invention has carbon arranged on the surface of such magnesium-aluminum oxide, and the carbon arranged on the surface provides conductivity. Further, since magnesium aluminum oxide is an inorganic oxide, it is excellent in thermal stability and stability in a solvent.
Therefore, the conductive material for a lithium ion secondary battery of the present invention improves both the electrical characteristics and the life characteristics of the lithium ion secondary battery by the ion exchange ability of the magnesium-aluminum oxide composite and the conductivity of carbon. ..

The metal ions unnecessary in the present invention refer to nickel ions, manganese ions, cobalt ions, copper ions, iron ions and the like. These unnecessary metal ions are derived from, for example, impurity ions present in the constituent materials of the lithium ion secondary battery or ions eluted from the positive electrode at a high temperature.

<Magnesium-aluminum oxide composite>
[Magnesium aluminum oxide]
The magnesium-aluminum oxide in the present invention is an oxide of magnesium and aluminum. By using an oxide of aluminum and silicon, the above-mentioned ion exchange ability can be exhibited. The magnesium-aluminum oxide in the present invention is not particularly limited as long as it is an oxide salt containing magnesium and aluminum, and may contain other metal elements. Examples of the magnesium aluminum oxide in the present invention include hydrotalcite.
The volume-based average particle size of the magnesium aluminum oxide is preferably 0.1 μm to 100 μm, preferably 0.5 μm to 50 μm, according to the final desired size of the magnesium aluminum oxide composite. Is more preferable, and 1 μm to 30 μm is even more preferable. The volume average particle size of the magnesium aluminum oxide is measured by using the laser diffraction method described later.

(Hydrotalcite)
The hydrotalcite of the present invention, having the composition a magnesium aluminum oxide has a crystalline structure of the layered, for _example, represented by _{Mg 6 Al 12 (CO 3)} (OH) 16 · 4H 2 O , etc. Things can be mentioned.

The hydrotalcite has a water content of preferably 10% by mass or less, and more preferably 5% by mass or less. When the water content is 10% by mass or less, it is possible to suppress the generation of gas that may be generated when electrolysis occurs, and it is possible to suppress the expansion of the battery. The water content can be measured by the Karl Fischer method. As a method for reducing the water content of mica to 10% by mass or less, a commonly used heating method can be used without particular limitation. Examples of the method for reducing the water content of mica to 10% by mass or less include a method of heat-treating under atmospheric pressure at 100 ° C. to 300 ° C. for about 6 hours to 24 hours.

The hydrotalcite in the present invention may be a synthetic one, or a commercially available product may be purchased and used. Examples of commercially available hydrotalcite products include the product name Kyoward 500 (Kyowa Chemical Industry Co., Ltd.).

[Carbon coating]
In the magnesium-aluminum oxide composite according to the present invention, carbon is arranged on the surface of the magnesium-aluminum oxide. The carbon to be arranged is arranged on at least a part or all of the surface of the magnesium aluminum oxide composite.

The carbon may be arranged on the surface of the magnesium aluminum oxide. 1 to 5 are schematic cross-sectional views showing an example of the configuration of the magnesium-aluminum oxide composite according to the present invention.
In FIG. 1, carbon 10 covers the entire surface of magnesium aluminum oxide 20. In FIG. 2, carbon 10 covers the entire surface of the magnesium aluminum oxide 20, but the thickness of carbon 10 varies. Further, in FIG. 3, carbon 10 is partially present on the surface of the magnesium aluminum oxide 20, and the surface of the magnesium aluminum oxide 20 has a portion not covered with the carbon 10. In FIG. 4, particles of carbon 10 having a particle size smaller than that of magnesium aluminum oxide 20 are present on the surface of magnesium aluminum oxide 20. FIG. 5 is a modification of FIG. 4, in which the particle shape of carbon 10 is scaly. In FIGS. 1 to 5, the shape of the magnesium aluminum oxide 20 is schematically represented by a spherical shape (circle as a cross-sectional shape), but the shape is spherical, block-shaped, scaly, or polygonal in cross-sectional shape. It may be any shape (shape with corners) and the like.
When the magnesium-aluminum oxide is composed of a plurality of tubular objects, it is only necessary that carbon is microscopically arranged on at least a part or all of the outer wall of the tubular object, and at least a part or all of the inner wall. Carbon may be arranged.
When fine magnesium-aluminum oxides are aggregated, bonded or aggregated to form particles, carbon may be arranged on at least a part or all of the particle surface, and the inside of the particles is aggregated, bonded or aggregated. If the particles have pores, carbon may be arranged in a part or all of the pores.

[Characteristics of magnesium-aluminum oxide composite]
The carbon content ratio in the magnesium-aluminum oxide composite is preferably 0.1% by mass to 50% by mass. When the carbon content is 0.1% by mass or more, the conductivity of the magnesium aluminum oxide composite tends to be further improved, and when it is 50% by mass or less, the metal ion adsorption capacity of the magnesium aluminum oxide composite is high. Tends to be more useful. The carbon content ratio in the magnesium-aluminum oxide composite is more preferably 0.5% by mass to 40% by mass, and further preferably 1% by mass to 30% by mass.
The carbon content in the magnesium-aluminum oxide composite is determined by using a differential thermal-thermogravimetric analyzer (TG-DTA) at a heating rate of 20 ° C / min and a mass reduction rate at 800 ° C for 20 minutes. Be measured.

Magnesium Aluminum oxide complex in a Raman spectrum obtained by laser Raman spectroscopy of the excitation wavelength 532 nm, the intensity of the peak appearing in the vicinity of 1360 cm ^-1 Id, the intensity of the peak appearing in the vicinity of 1580 cm ^-1 and Ig, its When the intensity ratio Id / Ig (D / G) of both peaks is taken as the R value, the R value is preferably 0.1 to 5.0, and more preferably 0.3 to 3.0. It is preferably 0.5 to 1.5, and more preferably 0.5 to 1.5. When the R value is 0.1 or more, the surface coating effect of amorphous carbon tends to be excellent, and when it is 5.0 or less, the surface coating carbon amount tends to be prevented from becoming excessive.

Here, the peak appearing in the vicinity of 1360 cm ^-1 is a peak usually identified to correspond to the amorphous structure of carbon, and means, for example, a peak observed in 1300 cm ^{-1 to} 1400 cm ^-1 . Further a peak appearing near 1580 cm ^-1, generally a peak identified as corresponding to the crystal structure of the carbon, for ^example, refers to peaks observed at 1530cm ^-1 ~1630cm -1.
The R value is analyzed by Raman spectrum using a Raman spectrum measuring device (for example, JASCO Corporation, NSR-1000 type, excitation wavelength 532 nm) with the entire measurement range (830 cm ^{-1 to} 1940 cm ^-1 ) as the baseline. Can be obtained from.

The powder resistance of the magnesium-aluminum oxide composite is preferably 0.001 Ω · cm to 100 Ω · cm, more preferably 0.001 Ω · cm to 50 Ω · cm, and 0.001 Ω · cm to 0.001 Ω · cm. It is more preferably 30 Ω · cm, and particularly preferably 0.001 Ω · cm to 10 Ω · cm. When the powder resistance of the magnesium-aluminum oxide composite is 0.001 Ω · cm or more, the metal ion adsorption capacity of the magnesium-aluminum oxide composite tends to be more maintained, and when it is 100 Ω · cm or less, the magnesium-aluminum oxide composite tends to be maintained. The body tends not to interfere with the battery characteristics of lithium-ion secondary batteries.
The powder resistivity is the value of the volume resistivity measured at a pressure of 3842 N / cm ² (382 Kgf / cm ² ) using a powder resistivity measurement system (for example, Mitsubishi Chemical Analytech Co., Ltd., Lorester GP). To do.

The volume average particle size of the magnesium-aluminum oxide composite is preferably 0.1 μm to 100 μm, more preferably 0.5 μm to 50 μm, and even more preferably 1 μm to 30 μm. When the volume average particle size of the magnesium-aluminum oxide composite is 0.1 μm or more, the handleability of the powder tends to be further improved, and when it is 100 μm or less, a coating film is used using a dispersion containing the magnesium-aluminum oxide composite. There is a tendency to obtain a more homogeneous film in the case of forming.

The volume average particle size of the magnesium-aluminum oxide composite is measured using a laser diffraction method. The laser diffraction method can be performed using a laser diffraction type particle size distribution measuring device (for example, Shimadzu Corporation, SALD3000J).
Specifically, the magnesium-aluminum oxide composite is dispersed in a dispersion medium such as water to prepare a dispersion. When a volume cumulative distribution curve is drawn from the small diameter side of this dispersion using a laser diffraction type particle size distribution measuring device, the particle diameter (D50) that is cumulative 50% is determined as the volume average particle diameter.
As for the "volume average particle diameter" in the present specification, the value measured according to the above method is used.

The magnesium aluminum oxide in the magnesium aluminum oxide composite is preferably at least one selected from the group consisting of mica, sepiolite, and talc from the viewpoint of metal ion adsorbing ability, metal ion selectivity, and electrical characteristics. ..

[Manufacturing method of magnesium aluminum oxide composite]
The method for producing a magnesium-aluminum oxide composite includes a step of obtaining a magnesium-aluminum oxide and a carbon-imparting step of imparting carbon to the surface of the obtained magnesium-aluminum oxide, and if necessary, includes other steps. ..

(Step to obtain magnesium aluminum oxide)
The step of obtaining the magnesium aluminum oxide may be a step including preparing the magnesium aluminum oxide as long as the magnesium aluminum oxide to be imparted carbon can be obtained, and the magnesium source and the aluminum source may be used. It may be a step including the production of magnesium aluminum oxide from. As for the method for producing magnesium aluminum oxide, the methods described above for various magnesium aluminum oxides can be applied. As a preparation of magnesium-aluminum oxide, it is possible to obtain a commercially available product or the like and use it as it is.

(Carbon addition process)
In the carbon addition step, carbon is added to the surface of the magnesium aluminum oxide. As a result, carbon is arranged on the surface of the magnesium aluminum oxide. The method for imparting carbon to the surface of the magnesium aluminum oxide is not particularly limited, and examples thereof include a wet mixing method, a dry mixing method, and a chemical vapor deposition method. Wet mixing method (“wet method”) because it is easy to make the thickness of carbon applied to the surface of magnesium aluminum oxide uniform, it is easy to control the reaction system, and it is possible to process under atmospheric pressure. There is) or a dry mixing method (sometimes referred to as "gas phase method") is preferred.

In the case of the wet mixing method, for example, magnesium aluminum oxide and a solution in which a carbon source is dissolved in a solvent are mixed, and the solution of the carbon source is adhered to the surface of the magnesium aluminum oxide, and if necessary, a solvent is used. Is then removed, and then heat treatment is performed in an inert atmosphere to carbonize the carbon source and impart carbon to the surface of the magnesium aluminum oxide. If the carbon source is insoluble in the solvent, a dispersion liquid in which the carbon source is dispersed in a dispersion medium can be used.
The content of the carbon source in the solution or dispersion of the carbon source is preferably 0.01% by mass to 30% by mass, and is 0.05% by mass to 20% by mass from the viewpoint of ease of dispersion. Is more preferable, and 0.1% by mass to 10% by mass is further preferable. The mixing ratio of magnesium aluminum oxide and carbon source (magnesium aluminum oxide: carbon source) shall be 100: 1 to 100: 500 in terms of mass ratio from the viewpoint of achieving both metal ion adsorption ability and conductivity. Is preferable, and 100: 5 to 100: 300 is more preferable.

In the case of the dry mixing method, for example, magnesium aluminum oxide and a carbon source are mixed with each other to form a mixture, and the carbon source is carbonized by heat treatment of this mixture in an inert atmosphere to oxidize magnesium aluminum. Carbon can be added to the surface of an object. When the magnesium aluminum oxide and the carbon source are mixed, a treatment for applying mechanical energy (for example, a mechanochemical treatment) may be performed.
The mixing ratio of magnesium aluminum oxide and carbon source (magnesium aluminum oxide: carbon source) when mixing magnesium aluminum oxide and carbon source between solids is from the viewpoint of both metal ion adsorption ability and conductivity. Therefore, the mass ratio is preferably 100: 1 to 100: 500, and more preferably 100: 5 to 100: 300.

When carbon is added to the surface of the magnesium aluminum oxide by the above method, the carbon source is not particularly limited, but may be a compound capable of leaving carbon by heat treatment, and specifically, a phenol resin. Polymer compounds such as styrene resin, polyvinyl alcohol, polyvinyl chloride, polyvinyl acetate, polyvinyl chloride; heat ethylene heavy end pitch, coal pitch, petroleum pitch, coal tar pitch, asphalt decomposition pitch, polyvinyl chloride (PVC), etc. Examples include PVC pitch produced by decomposition, pitch such as naphthalene pitch produced by polymerizing naphthalene and the like in the presence of a super strong acid; and polysaccharides such as starch and cellulose. These carbon sources may be used alone or in combination of two or more.

In the case of the chemical vapor deposition method, a known method can be applied. For example, carbon is imparted to the surface of the magnesium aluminum oxide by heat-treating the magnesium aluminum oxide in an atmosphere containing a gas in which the carbon source is vaporized. Can be done.

When carbon is added to the surface of a magnesium aluminum oxide by a chemical vapor deposition method, the carbon source is an aliphatic hydrocarbon, an aromatic hydrocarbon, an alicyclic hydrocarbon, or a derivative thereof, which is gaseous or easy. It is preferable to use a gaspizable compound. Specific examples thereof include hydrocarbons such as methane, ethane, propane, toluene, benzene, xylene, styrene, naphthalene and anthracene, and derivatives such as cresol. These carbon sources may be used alone or in combination of two or more.

The heat treatment temperature for carbonizing the carbon source is not particularly limited as long as the temperature at which the carbon source is carbonized, and is preferably 500 ° C. or higher, more preferably 600 ° C. or higher, and 700 ° C. or higher. It is more preferable to have. Further, from the viewpoint of low crystallinity of carbon, it is preferably 1300 ° C. or lower, more preferably 1200 ° C. or lower, and further preferably 1100 ° C. or lower.

The heat treatment time is appropriately selected depending on the type of carbon source used or the amount thereof applied, and is preferably 0.1 hour to 10 hours, more preferably 0.5 hour to 5 hours, for example.

The heat treatment is preferably carried out in an inert atmosphere such as nitrogen or argon. The heat treatment apparatus is not particularly limited as long as a reaction apparatus having a heating mechanism is used, and examples thereof include a heating apparatus capable of processing by a continuous method, a batch method, or the like. Specifically, a fluidized bed reactor, a rotary furnace, a vertical mobile bed reactor, a tunnel furnace, a batch furnace and the like can be appropriately selected according to the purpose.

Since individual particles of the heat-treated product obtained by the heat treatment may be agglomerated, it is preferable to perform a crushing treatment. Further, if it is necessary to adjust the average particle size to a desired value, further pulverization treatment may be performed.

Further, as another method of imparting carbon to the surface of the magnesium aluminum oxide, for example, as the carbon to be imparted to the surface of the magnesium aluminum oxide, amorphous carbon such as soft carbon and hard carbon, carbon such as graphite, etc. A method using a substance can be mentioned. According to this method, the magnesium aluminum oxide composite in which carbon 10 is present as particles on the surface of magnesium aluminum oxide 20 as shown in FIGS. 4 and 5 can also be produced. As a method using a carbonaceous substance, a wet mixing method or a dry mixing method can be applied.

When the wet mixing method is applied, particles of a carbonaceous substance and a dispersion medium are mixed to form a dispersion liquid, and this dispersion liquid and magnesium aluminum oxide are further mixed to obtain a surface of the magnesium aluminum oxide. It is produced by attaching a dispersion liquid, drying it, and then heat-treating it. When a binder is used, particles of a carbonaceous substance, an organic compound serving as a binder (a compound capable of leaving carbon by heat treatment) and a dispersion medium are mixed to form a mixture, and this mixture and magnesium aluminum are mixed. It is also possible to impart carbon to the surface of the magnesium aluminum oxide by adhering the mixture to the surface of the magnesium aluminum oxide by further mixing with the oxide, drying it, and then heat-treating it. The organic compound is not particularly limited as long as it is a compound capable of leaving carbon by heat treatment. Further, as the heat treatment conditions when the wet mixing method is applied, the heat treatment conditions for carbonizing the carbon source can be applied.

When applying the dry mixing method, particles of a carbonaceous substance and magnesium aluminum oxide are mixed with each other to form a mixture, and mechanical energy is added to the mixture as needed (for example, mechanochemical treatment). ) Is performed. Even when the dry mixing method is applied, it is preferable to perform heat treatment in order to generate silicon crystallites in the magnesium aluminum oxide. As the heat treatment conditions when the dry mixing method is applied, the heat treatment conditions for carbonizing the carbon source can be applied.

When the magnesium aluminum oxide is obtained by production, the method for producing the magnesium aluminum oxide composite is when a carbon source is supplied at any stage of the step of obtaining the magnesium aluminum oxide to obtain the magnesium aluminum oxide. It may be a production method for obtaining a magnesium-aluminum oxide composite by arranging carbon on the surface thereof. In this production method, a carbon source is supplied to the synthetic or desalted magnesium aluminum oxide dispersion, and the obtained magnesium aluminum oxide dispersion containing the carbon source is heat-treated to carbonize the carbon source. Can be offered to. By heat-treating the carbon source-containing dispersion, a magnesium-aluminum oxide composite having carbon on the surface can be obtained.

When the carbon source is supplied to the dispersion liquid of magnesium aluminum oxide, the content of the carbon source in the dispersion liquid is preferably 0.005% by mass to 5% by mass, preferably 0.01% by mass to 3% by mass. Is more preferable, and 0.05% by mass to 1.5% by mass is further preferable. When the content of the carbon source is 0.005% by mass or more, the conductivity of the magnesium aluminum oxide composite tends to be further improved, and when it is 5% by mass or less, the magnesium aluminum oxide composite tends to be further improved. There is a tendency to make better use of the metal ion adsorption capacity of.

<Other ingredients>
The conductive material for a lithium ion secondary battery of the present invention may contain any component in addition to the magnesium-aluminum oxide composite. The other components that can be contained in the conductive material for the lithium ion secondary battery are not particularly limited as long as they are components that can be generally contained in the conductive material for the lithium ion secondary battery. Examples of other components that can be contained in the conductive material for a lithium ion secondary battery include carbon black, graphite, acetylene black, an oxide exhibiting conductivity, a nitride exhibiting conductivity, and the like. The conductive material for a lithium ion secondary battery of the present invention preferably contains acetylene black from the viewpoint of ease of use when made into a slurry.

<Composition for forming negative electrode of lithium ion secondary battery>
The composition for forming a negative electrode of a lithium ion secondary battery of the present invention contains the above-mentioned conductive material for a lithium ion secondary battery, a negative electrode active material, and a binder. The composition for forming a negative electrode of a lithium ion secondary battery of the present invention may further contain a solvent, a thickener, a conductive auxiliary agent and the like.

The content of the magnesium-aluminum oxide composite in the composition for forming the negative electrode of the lithium ion secondary battery is not particularly limited, and for example, the composition for forming the negative electrode of the lithium ion secondary battery excluding the solvent used as needed. It can be 0.1% by mass to 30% by mass, preferably 0.3% by mass to 20% by mass, and more preferably 0.5% by mass to 10% by mass, based on the total amount of the above. preferable.

As the negative electrode active material, a normal material used for a negative electrode for a lithium ion secondary battery can be applied. Examples of the negative electrode active material include carbon materials capable of doping or intercalating lithium ions, metal compounds, metal oxides, metal sulfides, conductive polymer materials, etc., and natural graphite, artificial graphite, silicon, etc. Examples thereof include lithium titanate. As the negative electrode active material, these can be used alone or in combination of two or more.

The binder is not particularly limited, and for example, a styrene-butadiene copolymer; methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylonitrile, hydroxyethyl (meth) acrylate and the like. (Meta) acrylic copolymer obtained by copolymerizing the ethylenically unsaturated carboxylic acid ester of the above with an ethylenically unsaturated carboxylic acid such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid, and maleic acid; polyfluoride. Examples thereof include polymer compounds such as vinylidene, polyethylene oxide, polyepicchlorohydrin, polyphosphazene, polyacrylonitrile, polyimide and polyamideimide. In addition, "(meth) acrylate" means "acrylate" and the corresponding "methacrylate". The same applies to other similar expressions such as "(meth) acrylic copolymer".

The solvent is not particularly limited, and N-methylpyrrolidone, dimethylacetamide, dimethylformamide, γ-butyrolactone and the like can be used.

The thickener is not particularly limited, and carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, polyacrylic acid (salt), oxidized starch, phosphorylated starch, casein and the like can be used.

The conductive auxiliary agent is not particularly limited, and carbon black, acetylene black, an oxide exhibiting conductivity, a nitride exhibiting conductivity, and the like can be used. These conductive auxiliaries may be used alone or in combination of two or more.

<Composition for forming positive electrode of lithium ion secondary battery>
The composition for forming a positive electrode of a lithium ion secondary battery of the present invention contains the above-mentioned conductive material for a lithium ion secondary battery, a positive electrode active material, and a binder. The composition for forming a positive electrode of a lithium ion secondary battery of the present invention may further contain a solvent, a thickener, a conductive auxiliary agent and the like.

The content of the magnesium-aluminum oxide composite in the composition for forming the positive electrode of the lithium ion secondary battery is not particularly limited, and for example, the composition for forming the positive electrode of the lithium ion secondary battery excluding the solvent used as needed. It can be 0.1% by mass to 30% by mass, preferably 0.3% by mass to 20% by mass, and more preferably 0.5% by mass to 10% by mass, based on the total amount of the above. preferable.

As the positive electrode active material, a normal material used for a positive electrode for a lithium ion secondary battery can be applied. The positive electrode active material may be a compound capable of doping or intercalating lithium ions, for example, lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), lithium manganate (LiMnO ₂ ), and nickel manganese cobalt. Examples thereof include lithium oxide (Li (NiCoAl) O ₂ ).

Examples of the binder in the composition for forming a positive electrode of a lithium ion secondary battery include the binder described in the composition for forming a negative electrode of a lithium ion secondary battery. As the solvent, thickener and conductive auxiliary agent optionally contained in the composition for forming the positive electrode of the lithium ion secondary battery, those described in the composition for forming the negative electrode of the lithium ion secondary battery can be mentioned.

<Negative electrode for lithium ion secondary battery>
The negative electrode for a lithium ion secondary battery of the present invention (hereinafter, may be abbreviated as "negative electrode") is a current collector, and the above-mentioned conductive material for a lithium ion secondary battery and negative electrode activity provided on the current collector. It has a negative electrode layer containing a substance.
For example, for the negative electrode for a lithium ion secondary battery of the present invention, the above-mentioned composition for forming a negative electrode of a lithium ion secondary battery is prepared, and the composition for forming a negative electrode of a lithium ion secondary battery is applied to a current collector. It is obtained by removing the optionally contained solvent and performing pressure molding to form a negative electrode layer. Generally, the composition for forming a negative electrode of a lithium ion secondary battery is formed into a sheet shape, a pellet shape, or the like after kneading.
When the negative electrode for a lithium ion secondary battery of the present invention is manufactured using the composition for forming a negative electrode of a lithium ion secondary battery, the negative electrode layer contains a binder.

The material of the current collector is not particularly limited, and examples thereof include aluminum, copper, nickel, titanium, stainless steel, porous metal (foam metal), and carbon paper. The shape of the current collector is not particularly limited, and examples thereof include a foil shape, a perforated foil shape, and a mesh shape.

The method of applying the composition for forming the negative electrode of the lithium ion secondary battery to the current collector is not particularly limited, and for example, a metal mask printing method, an electrostatic coating method, a dip coating method, a spray coating method, a roll coating method, etc. The doctor blade method, the gravure coating method and the screen printing method can be mentioned. After the application, it is preferable to perform a pressurizing treatment with a flat plate press, a calender roll or the like, if necessary. Further, the composition for forming the negative electrode of the lithium ion secondary battery molded into a sheet shape, a pellet shape, or the like and the current collector are integrated by, for example, integration by a roll, integration by a press, or a combination thereof. It can be done by integration.

The negative electrode layer formed on the current collector or the negative electrode layer integrated with the current collector is preferably heat-treated according to the binder used. For example, when a binder having polyacrylonitrile as a main skeleton is used, heat treatment is preferably performed at 100 ° C. to 180 ° C., and when a binder having polyimide or polyamideimide as a main skeleton is used, heat treatment is preferably performed at 150 ° C. to 180 ° C. It is preferable to heat-treat at 450 ° C. By this heat treatment, the solvent used as needed is removed and the strength is increased by curing the binder, and the adhesion between the negative electrode materials and the adhesion between the negative electrode material and the current collector tend to be improved. In addition, these heat treatments are preferably carried out in an inert atmosphere such as helium, argon or nitrogen or in a vacuum atmosphere in order to prevent oxidation of the current collector during the treatment.

Further, it is preferable that the negative electrode is pressed (pressurized) before the heat treatment. The electrode density can be adjusted by pressurizing. It The negative electrode for a lithium ion secondary battery of the present invention, it is preferable that the electrode density of ^{1.4g / cm 3 ~1.9g / cm 3} , a 1.5g / cm ³ ~1.85g / cm 3 it is more ^preferable, and further preferably from ^{1.6g / cm 3 ~1.8g / cm 3} . As for the electrode density, the higher the value, the more the volume capacity of the negative electrode tends to improve, and the adhesion between the negative electrode materials and the adhesion between the negative electrode material and the current collector tend to improve.

<Positive electrode for lithium ion secondary battery>
The positive electrode for a lithium ion secondary battery of the present invention (hereinafter, may be abbreviated as "positive electrode") is a current collector, and the above-mentioned conductive material for a lithium ion secondary battery and positive electrode activity provided on the current collector. It has a positive electrode layer containing a substance.
Examples of the current collector in the positive electrode for a lithium ion secondary battery include the current collector described in the negative electrode for a lithium ion secondary battery. The positive electrode for a lithium ion secondary battery is similarly obtained by replacing the composition for forming a negative electrode of a lithium ion secondary battery with the composition for forming a positive electrode of a lithium ion secondary battery in the above-mentioned method for producing a negative electrode for a lithium ion secondary battery. It can be manufactured by the method of.

<Lithium-ion secondary battery>
The lithium ion secondary battery of the present invention includes at least one of the above-mentioned negative electrode for a lithium ion secondary battery and the above-mentioned positive electrode for a lithium ion secondary battery. When a negative electrode other than the above-mentioned negative electrode for a lithium ion secondary battery is used, a normal negative electrode used for the lithium ion secondary battery can be applied. Further, when a positive electrode other than the above-mentioned positive electrode for a lithium ion secondary battery is used, a normal positive electrode used for the lithium ion secondary battery can be applied.
A lithium ion secondary battery can be formed by arranging the negative electrode and the positive electrode so as to face each other via a separator and injecting an electrolytic solution containing an electrolyte.

The electrolytic solution is not particularly limited, and known ones can be used. For example, a non-aqueous lithium ion secondary battery can be manufactured by using a solution in which an electrolyte is dissolved in an organic solvent as the electrolytic solution.

As the electrolyte, for _{example, LiPF 6, LiClO 4, LiBF} 4, LiClF 4, LiAsF 6, LiSbF 6, LiAlO 4, LiAlCl 4, LiN (CF 3 SO 2) 2, LiN (C 2 F 5 SO 2) 2 , LiC (CF ₃ SO ₂ ) ₃ , LiCl and LiI.

As the separator, various known separators can be used. Specific examples thereof include a paper separator, a polypropylene separator, a polyethylene separator, and a glass fiber separator.

As a method for manufacturing a lithium ion secondary battery, for example, first, two electrodes, a positive electrode and a negative electrode, are wound via a separator. The obtained spiral winding group is inserted into the battery can, and the tab terminal previously welded to the current collector of the negative electrode is welded to the bottom of the battery can. The electrolytic solution is injected into the obtained battery can, and the tab terminal previously welded to the positive electrode current collector is welded to the battery lid, and the lid is placed on the upper part of the battery can via an insulating gasket. Then, the battery is obtained by crimping and sealing the part where the lid and the battery can are in contact with each other.

The form of the lithium ion secondary battery of the present invention is not particularly limited, and examples thereof include lithium ion secondary batteries such as paper type batteries, button type batteries, coin type batteries, laminated batteries, cylindrical batteries, and square batteries. ..

Next, the present invention will be described with reference to Examples, but the scope of the present invention is not limited to these Examples.

[Example 1]
A hydrotalcite composite as a magnesium-aluminum oxide composite was prepared as follows.
As the hydrotalcite, a product name: Kyoward 500 (Kyowa Chemical Industry Co., Ltd.) was used. The various physical properties of this mica were as follows. The BET specific surface area and volume average particle size were measured under the following conditions.
BET specific surface area: 100 m ² / g
Volume average particle size: 3.0 μm

(BET specific surface area)
The BET specific surface area was measured based on the nitrogen adsorption capacity. A nitrogen adsorption measuring device (AUTOSORB-1, QUANTACHROME) was used as the evaluation device. When performing the measurement, after pretreatment of the sample described later, the evaluation temperature is set to 77K, and the evaluation pressure range is set to less than 1 in relative pressure (equilibrium pressure with respect to saturated vapor pressure).

As a pretreatment, degassing and heating were automatically controlled by a vacuum pump in the measurement cell in which 0.05 g of the sample was charged. The detailed conditions for this treatment were set to reduce the pressure to 10 Pa or less, heat at 110 ° C., hold for 3 hours or more, and then naturally cool to room temperature (25 ° C.) while maintaining the reduced pressure. Hereinafter, in the examples, the BET specific surface area was measured in the same manner.

(Volume average particle size)
The volume average particle size was measured as follows.
The measurement sample (5 mg) was placed in a 0.01 mass% aqueous solution of a surfactant (Esomin T / 15, Lion Corporation) and dispersed with a vibration stirrer. The obtained dispersion was placed in a sample water tank of a laser diffraction type particle size distribution measuring device (SALD3000J, Shimadzu Corporation), circulated by a pump while applying ultrasonic waves, and measured by a laser diffraction type. The measurement conditions were as follows.
The volume cumulative 50% particle size (D50%) of the obtained particle size distribution was defined as the volume average particle size. Hereinafter, in the examples, the volume average particle diameter was measured in the same manner.
-Light source: Red semiconductor laser (690 nm)
・ Absorbance: 0.10 to 0.15
-Refractive index: 2.00-0.20i

Using the above hydrotalcite, a hydrotalcite complex was produced as follows.
Mica and polyvinyl alcohol powder (Wako Pure Chemical Industries, Ltd.) were mixed at a mass ratio of 100:70 and calcined at 850 ° C. for 1 hour under a nitrogen atmosphere. This was designated as a mica complex.
The carbon content of the obtained mica composite was measured using a differential thermal-thermogravimetric analyzer (TG-DTA) at a heating rate of 20 ° C./min and a mass reduction rate at 800 ° C. for 20 minutes. When measured, it was 10% by mass.
Moreover, when the R value of the obtained mica complex was measured under the following conditions, it was 1.0. When mapping was performed by Raman spectroscopy and the coating condition of the surface of the hydrotalcite composite was confirmed, there were very few parts not coated with carbon, and most of the entire surface was coated with carbon. The coating was confirmed.
The various physical properties of the obtained hydrotalcite complex were as follows.
BET specific surface area: 20m ² / g
Volume average particle size: 3.5 μm

(R value)
A Raman spectrum measuring device (NSR-1000 type, JASCO Corporation) was used to measure the R value, and the obtained spectrum was defined in the following range as a baseline. The measurement conditions were as follows.
-Laser wavelength: 532 nm
・ Irradiation intensity: 1.5mW (measured value with laser power monitor)
・ Irradiation time: 60 seconds ・ Irradiation area: 4 μm ²
-Measurement range: 830 cm ^{-1 to} 1940 cm ^-1
-Baseline: 1050 cm ^{-1 to} 1750 cm ^-1

The wave number of the obtained spectrum is determined from the difference between the wave number of each peak obtained by measuring the reference substance inden (Wako Pure Chemical, Wako First Class) under the same conditions as above and the wave number theoretical value of each peak of inden. It was corrected using the obtained calibration curve.
Among the profile obtained after the correction, 1360 cm ^-1 to the intensity of the peak appearing in the vicinity of Id, and Ig the intensity of a peak appearing near 1580 cm ^-1, at both peak intensity ratio Id / Ig of (D / G) It was calculated as the R value.

The mapping was performed under the same conditions using the same Raman spectrum measuring device as that used for the measurement of the R value. Hereinafter, in the examples, the R value was measured in the same manner.

[Evaluation]
The following evaluation was performed on the hydrotalcite complex prepared in Example 1. As a comparative control, hydrotalcite and acetylene black (HS-100, Electrochemical Industry Co., Ltd.) before carbon addition were used.

(1) Powder resistivity and conductivity The volume resistivity and conductivity are 3842 N / cm ² (3842 N / cm ² ) by weighing 3 g of each sample and using a powder resistivity measurement system (Lorester GP, Mitsubishi Chemical Analytech Co., Ltd.). The measurement was carried out under a pressure of 382 kgf / cm ² ).
The results of each are shown in Table 1.

(2) Metal (Mn) ion adsorption ability in electrolytic solution The hydrotalcite complex prepared in Example 1, the hydrotalcite complex before carbon addition, and acetylene black were prepared in the electrolytic solution as follows. The metal (Mn) ion adsorption ability of the above was evaluated.
An electrolytic solution containing 1 M of LiPF ₆ and ethylene carbonate (EC): dimethyl carbonate (DMC): diethyl carbonate (DEC) in a volume ratio of 1: 1: 1 was prepared, and Mn (BF ₄ ) ₂ was added thereto. It was dissolved to prepare a 500 ppm Mn solution. After adding 0.05 g of each sample to this Mn solution and stirring for 30 minutes, the sample was allowed to stand overnight at room temperature. Then, the supernatant was filtered using a 0.45 μm filter, and the amount of Mn ions adsorbed was measured using an ICP emission spectrometer (ICP-AES). The results are shown in Table 1.

As described above, the metal ion adsorption ability of the hydrotalcite complex produced in Example 1 was maintained in the same manner as that of the hydrotalcite before carbon addition. Further, it is clear from the result of Evaluation 1 for the hydrotalcite complex of Example 1 that the conductivity is imparted by carbon addition.
From these facts, it was found that the hydrotalcite composite can improve the electrical characteristics and the life characteristics of the lithium ion secondary battery by using it as a conductive material and by using it as a conductive material.

(3) Charge / discharge characteristics To 90 parts by mass of hydrotalcite complex or acetylene black, 10 parts by mass of polyvinylidene fluoride (PVDF) is added and N-methyl-2-pyrrolidone (NMP) is used. It was kneaded to obtain a slurry. The obtained slurry was applied onto a copper foil, dried at 105 ° C. for 30 minutes, and then pressed to obtain an electrode. A coin cell (half cell) was produced by using the obtained electrode as a negative electrode, facing a metallic lithium counter electrode with a 20 μm polypropylene separator, and injecting an electrolytic solution. As the electrolytic solution, a mixture of ethyl carbonate and methyl ethyl carbonate in a mixed solvent having a volume ratio of 3: 7 was used, in which LiPF ₆ was dissolved at a concentration of 1 mol / L and vinylene carbonate was dissolved at a concentration of 0.5% by mass.

Each cell was placed in a constant temperature bath at 25 ° C. and a charge / discharge test was performed. Charging was carried out by charging to 0.005 V with a current of 0.1 mA and then inserting Li into the working electrode with a voltage of 0.005 V until the current value became 0.01 mA. The discharge was carried out by discharging Li to the working electrode with a current of 0.1 mA up to a voltage value of 1.5 V. The discharge capacity was the result obtained from the first charge / discharge test. The results are shown in Table 2.

From this, it was found that the hydrotalcite complex showed an initial discharge capacity of 280 mAh / g, and had the same or higher performance as that of 205 mAh / g of acetylene black.

(5) Storage test (addition to negative electrode)
To 5 parts by mass of hydrotalcite talcite complex, 1 part by mass of acetylene black, 3 parts by mass of polyvinylidene fluoride (PVDF), and 91 parts by mass of graphite were added to N-methyl-2-pyrrolidone. Kneading was performed using (NMP) to obtain a slurry. The obtained slurry was applied onto a copper foil, dried at 105 ° C. for 30 minutes, and then pressed to obtain a negative electrode containing a hydrotalcite composite. Here, the negative electrode containing the hydrotalcite composite is referred to as negative electrode A.
For comparison, 1 part by mass of acetylene black, 3 parts by mass of polyvinylidene fluoride (PVDF), and 96 parts by mass of graphite were added and kneaded with N-methyl-2-pyrrolidone (NMP). A negative electrode was obtained by the same method using the obtained slurry. This negative electrode is referred to as a negative electrode X.

8 parts by mass of acetylene black, 6 parts by mass of polyvinylidene fluoride (PVDF) and 86 parts by mass of spinel manganese were added and kneaded with N-methyl-2-pyrrolidone (NMP) to obtain a slurry. .. The obtained slurry was applied onto an aluminum foil, dried at 105 ° C. for 30 minutes, and then pressed to obtain a positive electrode X.

The negative electrodes A and X and the positive electrode X were each vacuum dried at 130 ° C. for 6 hours, and then the negative electrode and the positive electrode were opposed to each other through a 20 μm polypropylene separator, and an electrolytic solution was injected to prepare a coin cell. As the electrolytic solution, a mixture of ethyl carbonate and methyl ethyl carbonate in a mixed solvent having a volume ratio of 3: 7 was used, in which LiPF ₆ was dissolved at a concentration of 1 mol / L and vinylene carbonate was dissolved at a concentration of 0.5% by mass. Here, the coin cells produced by using the negative electrodes A and X are referred to as cell A and cell X, respectively.

(Addition to positive electrode)
N-Methyl-2 by adding 5 parts by mass of acetylene black, 6 parts by mass of polyvinylidene fluoride (PVDF), and 86 parts by mass of spinel manganese to each of 3 parts by mass of the hydrotalcite complex. -Kneading with pyrrolidene (NMP) gave a slurry. The obtained slurry was applied onto an aluminum foil, dried at 105 ° C. for 30 minutes, and then pressed to obtain a positive electrode containing a hydrotalcite composite. Here, the positive electrode containing the hydrotalcite complex is referred to as positive electrode B.
As a comparison, the positive electrode X was used.
As the negative electrode, the negative electrode X was used.
The negative electrode X and the positive electrodes B and X were each vacuum dried at 130 ° C. for 6 hours, then opposed to each other through a 20 μm polypropylene separator, and an electrolytic solution was injected to prepare a coin cell. As the electrolytic solution, a mixture of ethyl carbonate and methyl ethyl carbonate in a mixed solvent having a volume ratio of 3: 7 was used, in which LiPF ₆ was dissolved at a concentration of 1 mol / L and vinylene carbonate was dissolved at a concentration of 0.5% by mass. Here, the coin cells produced by using the positive electrodes B and X are referred to as cell D and cell X, respectively.

(Preservation conditions)
After putting each cell in a constant temperature bath at 25 ° C, it is charged to 0.0046V by constant current constant voltage charging with a voltage of 4.2V and a current of 0.46mA, and then a current of 0.46mA. It was discharged until it became 2.7 V. Next, each cell was charged to 0.0046 V by constant current constant voltage charging having a voltage of 4.2 V and a current of 0.46 mA to obtain a charge capacity. Each cell after charging was placed in a constant temperature bath at 60 ° C. and allowed to stand for 7 days. Each cell after standing was discharged with a current of 0.46 mA until it became 2.7 V to obtain a discharge capacity.
(Initial discharge capacity after leaving for 7 days) / (Initial charge capacity before leaving for 7 days) was defined as the capacity retention rate. Table 3 shows the case where the hydrotalcite complex is added to the negative electrode, and Table 4 shows the case where the hydrotalcite complex is added to the positive electrode.

From this, the addition of hydrotalcite complex to the negative electrode or positive electrode of the lithium ion secondary battery was found to improve the capacity retention ratio compared with the case of no addition of this.

Therefore, the magnesium-aluminum oxide composite in the present invention exhibits both ion exchange ability and conductivity by carbon, and the magnesium-aluminum oxide composite in the present invention is used as an electrode (positive electrode / negative electrode) of a lithium ion secondary battery. ), It can be seen that the electrical characteristics and life characteristics of the lithium ion secondary battery can be improved. The present invention is for forming a negative electrode of a lithium ion secondary battery using a conductive material for a lithium ion secondary battery which can impart excellent electrical characteristics and life characteristics of a lithium ion secondary battery, and a conductive material for a lithium ion secondary battery. A composition, a composition for forming a positive electrode of a lithium ion secondary battery, a negative electrode for a lithium ion secondary battery, a positive electrode for a lithium ion secondary battery, and a lithium ion secondary battery can be provided.

10 carbon 20 magnesium aluminum oxide

Claims (9)

A conductive material for a lithium ion secondary battery containing a magnesium-aluminum oxide composite having a magnesium-aluminum oxide and carbon arranged on the surface of the magnesium-aluminum oxide. The conductive material for a lithium ion secondary battery according to claim 1, wherein the carbon content ratio in the magnesium aluminum oxide composite is 0.1% by mass to 50% by mass. The conductive material for a lithium ion secondary battery according to claim 1 or 2, wherein the R value obtained from the Raman spectrum analysis of the magnesium-alumina oxide composite is 0.1 to 5.0. The conductive material for a lithium ion secondary battery according to any one of claims 1 to 3, wherein the powder resistivity of the magnesium aluminum oxide composite is 0.001 Ω · cm to 100 Ω · cm. A composition for forming a negative electrode of a lithium ion secondary battery, which comprises the conductive material for a lithium ion secondary battery according to any one of claims 1 to 4, a negative electrode active material, and a binder. A composition for forming a positive electrode of a lithium ion secondary battery, which comprises the conductive material for a lithium ion secondary battery according to any one of claims 1 to 4, a positive electrode active material, and a binder. It has a current collector and a negative electrode layer provided on the current collector and containing the conductive material for a lithium ion secondary battery and the negative electrode active material according to any one of claims 1 to 4. Negative electrode for lithium-ion secondary batteries. It has a current collector and a positive electrode layer provided on the current collector and containing the conductive material for a lithium ion secondary battery and the positive electrode active material according to any one of claims 1 to 4. Positive electrode for lithium-ion secondary batteries. A lithium ion secondary battery comprising at least one of the negative electrode for a lithium ion secondary battery according to claim 7 and the positive electrode for a lithium ion secondary battery according to claim 8.