Toray Industries, Inc.

Eiichiro Tamaki

Yasuo Kubota

Manabu Kawasaki

Peiyu Sun

Zhenqi Wu

Gangqiao Liu

Koki Miyazono

Gang Wu

Hiroaki Kawamura

Hanxiao Yang

Takashi Konishi

Yoshihide Hirai

Koichiro Manabe

Jian Wang

Tomoyuki Yuba

Zhijun Chen

Tetsuo Yamashita

Natsuko Chayama

Miyuki Tabayashi

Mayumi Hara

Yusuke Kawabata

Toshiyuki Nonaka

Hironobu Tsuji

Ning Du

Miyuki Matsushita

Yutaka Katayama

A graphene dispersion liquid containing graphene dispersed in a dispersion medium is described, in which, in the graphene contained in the dispersion liquid, a proportion of graphene with a size in the plane direction of 500 nm or more and 1 μm or less is 30% or more on an area basis, and a proportion of graphene with a size in the plane direction of 10 μm or more and 50 μm or less is 30% or more on an area basis. The graphene dispersion liquid is in a stable dispersion state and forms a strong conductive path.

Graphene dispersion liquid, method for producing same, and electrode for secondary battery

A secondary battery electrode is provided that may achieve a non-aqueous electrolyte secondary battery having a high energy output density with a small amount of a conductive aid. The secondary battery electrode has a mixture layer containing graphene and a secondary battery active substance. The secondary battery electrode has a mean aspect ratio of 2.0 or greater in an electric conductive material portion from a cross section of the secondary battery electrode, as specified by the method described below. The method for specifying the electric conductive material portion comprises: (1) acquiring, by scanning spreading resistance microscopy, a mapping image and a histogram of spreading resistance values for a mixture layer portion; and (2), defining R1 as the lowest resistance value in the histogram, accumulating sequentially from R1 the frequency, defining R2 as the spreading resistance value when the cumulative frequency has exceeded 3% relative to the cumulative frequency over the entire data, further defining R3 as a spreading resistance value of ten times R2, and, with R3 serving as the threshold value, binarizing the mapping image to define as the electric conductive material portion the portion having a resistance value of R3 or lower.

Secondary battery electrode

An object of the present invention is to improve the electron conductivity and ion conductivity of the surface of a positive electrode active material to provide a lithium ion battery having high capacity and high output. The present invention relates to a positive electrode for a lithium ion secondary battery, including a mixture layer containing a positive electrode active material for a lithium ion secondary battery and graphene, wherein the mixture layer has a percentage of abundance of silicon composing a siloxane bond in total elements of 0.4 atomic % or more as measured by X-ray photoelectron spectroscopy.

Positive electrode for lithium ion secondary battery, graphene/positive electrode active material composite particles, manufacturing methods for same, and positive electrode paste for lithium ion secondary battery

A graphene/organic solvent dispersion liquid is in a stably dispersed state and also unlikely to cause electrolysis of water. A graphene/organic solvent dispersion liquid is also provided including graphene dispersed in an organic solvent and having a value of (W2&#x2212;W1)/G in the range of 0.005 or more and 0.05 or less, wherein W1 and W2 are the water fractions measured at 130&#xb0; C. and 250&#xb0; C., respectively, by the Karl Fischer's method and G is the solid fraction of the graphene.

Graphene/organic solvent dispersion and method for producing same, and method for producing lithium-ion battery electrode

The purpose of the present invention is to provide a graphene dispersion which has high dispersibility and which is capable of exhibiting high electrical conductivity and ionic conductivity when used as a raw material for producing an electrode material. The present invention provides a graphene dispersion including a graphene, an amine compound having a molecular weight of 150 or less, and an organic solvent, wherein the mass ratio of an amine compound to the graphene is 0.005 or more and 0.30 or less.

Graphene dispersion, method for producing electrode paste, and method for producing electrode

The purpose of the present invention is to provide a graphene which has high dispersibility, high electrical conductivity and oxidation resistance namely a graphene which has high electrochemical stability. In order to achieve the above-described purpose, a surface-treated graphene according to the present invention is obtained by having a compound represented by general formula (1) or a neutralized salt thereof adhere to a graphene. In general formula (1), A represents a benzene-based aromatic group with a condensation number of 1-4, which has no phenolic hydroxy group; Rrepresents a direct bond, a divalent hydrocarbon group having 1-12 carbon atoms, or a divalent organic group having 1-12 carbon atoms, which has a structure selected from the group consisting of an ether bond, an ester bond, an alcohol structure and a carbonyl structure; each of Rand Rindependently represents a hydrogen atom, a hydrocarbon group having 1-12 carbon atoms, or an organic group having 1-12 carbon atoms, which has a structure selected from the group consisting of an ether bond, an ester bond, an alcohol structure and a carbonyl structure; and n represents an integer of 1-6. 

Surface-treated graphene, surface-treated graphene/organic solvent dispersion liquid, surface-treated graphene/electrode active material composite particles and electrode paste

A graphene material has a specific form that has a high dispersibility and can maintain a high electric conductivity and ion conductivity when used as material for electrode manufacturing. A graphene dispersion liquid is provided including graphene dispersed in an organic solvent and meeting both 0.5 &#x3bc;m&#x2264;S&#x2264;15 &#x3bc;m and 1.0&#x2264;D/S&#x2264;3.0 wherein D is the median diameter (&#x3bc;m) of the graphene measured by the laser diffraction/scattering type particle size distribution measurement method and S is the average size (&#x3bc;m) in the planar direction of the graphene calculated from the arithmetic mean of the longest diameter and shortest diameter of the graphene observed by a laser microscope.

Graphene dispersion, process for producing same, process for producing particles of graphene/active material composite, and process for producing electrode paste

A graphene material in a specific form is provided that has a high dispersibility and can maintain a high electric conductivity and ion conductivity when used as material for electrode manufacturing. A graphene dispersion liquid is provided including graphene dispersed in a solvent having a N-methyl pyrolidone content of 50 mass % or more and, when diluted with N-methylpyrolidone to a graphene weight fraction of 0.000013, giving a diluted solution having a weight-based absorptivity coefficient, which is calculated by Equation (1) given below, of 25,000 cm&#x2212;1 or more and 200,000 cm&#x2212;1 or less at a wavelength of 270 nm:weight-based absorptivity coefficient (cm)=absorbance/{0.000013&#xd7;cell's optical path length (cm)}.&#x2003;&#x2003;(1)

Provided are a laminate that has high smoothness, planar homogeneity, and substrate adhesion and undergoes little change in physical properties even if degradation of surface quality due to physical contact in use has occurred, and a method for producing the homogeneous laminate in a convenient manner in a small number of steps. A laminate includes a substrate made of a polymer material and a partially oxidized thin layer graphite piece layer including partially oxidized thin layer graphite pieces and having an average thickness to of 3.0 nm to 10,000 nm, the layer being formed on the substrate and bonded to the substrate via a chemical bond.

Layered product and process for producing same

A method is provided for producing polyanionic positive electrode active material composite particles, which comprises: a step 1 wherein precursor composite granulated bodies, each of which contains a polyanionic positive electrode active material precursor particle in graphite oxide, are formed by mixing a polyanionic positive electrode active material precursor and graphite oxide; and a step 2 wherein the precursor composite granulated bodies obtained in step 1 are heated at 500&#xb0; C. or higher in an inert atmosphere or in a reducing atmosphere. The maximum intensity of the X-ray diffraction peak based on the positive electrode active material is less than 50% of the maximum intensity of the X-ray diffraction peak based on the materials other than the positive electrode active material. The maximum intensity of the X-ray diffraction peak based on the positive electrode active material is 50% or more of the maximum intensity of the X-ray diffraction peak based on the materials other than the positive electrode active material.

Method for producing polyanionic positive electrode active material composite particles, and polyanionic positive electrode active material precursor-graphite oxide composite granulated bodies

A conventional positive electrode material for lithium ion batteries that is made of positive electrode active material/graphene composite particles has low graphene material ion conductivity and is incapable of providing favorable battery performance. In the present invention, positive electrode active material/graphene composite particles are conferred with high electron conductivity and ion conductivity by formation of an appropriately functionalized graphene/positive electrode active material composite, and are capable of yielding a high-capacity/high-output lithium ion secondary battery when used as a positive electrode active material for a lithium ion battery.

Positive electrode active material/graphene composite particles, positive electrode material for lithium ion cell, and method for manufacturing positive electrode active material/graphene composite particles

In order to prepare a highly conductive and highly dispersible graphene powder and to obtain an electrode for a lithium ion battery with excellent performance utilizing the highly conductive and highly dispersible graphene, a graphene powder and a preparation method thereof is provided. The graphene powder comprises a compound having a catechol group adsorbing on the surface of graphene in a weight ratio of 5-50% relative to the grapheme and the element ratio of oxygen to carbon in the graphene powder measured by X-ray photoelectron spectroscopy is 0.06 or more and 0.20 or less. The method for producing a graphene powder comprise the step of reducing a graphite oxide with a reducing agent having no catechol group in the presence of a compound having a catechol group.

Graphene powder, method for producing graphene powder and electrode for lithium ion battery containing graphene powder

The present invention relates to preparation of a highly dispersible graphene powder. Further, the present invention includes providing an electrode for a lithium ion battery having good output characteristics and cycle characteristics by utilizing a highly dispersible graphene powder. The present invention also includes providing a graphene powder having a specific surface area of 80 m/g or more to 250 m/g or less as measured by BET measurement, and an oxygen-to-carbon element ratio of 0.09 or more to 0.30 or less as measured by X-ray photoelectron spectroscopy.

Graphene powder, electrode paste for lithium ion battery and electrode for lithium ion battery

Provided is a graphene composite primarily used as a conductive additive for forming an electrode for lithium ion batteries, which has performance equal to or higher than conventional dispersants and is deceased in cost by using an inexpensive and easily available dispersant. The graphene composite includes a graphene powder and a compound having a structure of pyrazolone.

Graphene composite, method for producing graphene composite and electrode for lithium ion battery containing graphene composite

The present invention makes a lithium ion secondary cell exhibit high capacity when lithium manganese phosphate is used as the active material of the lithium ion secondary cell. The present invention is directed to lithium manganese phosphate nanoparticles having a ratio I/Iof the peak intensity at 20&#xb0; to the peak intensity at 29&#xb0; obtained by X-ray diffraction of greater than or equal to 0.88 and less than or equal to 1.05, and a crystallite size determined by X-ray diffraction of greater than or equal to 10 nm and less than or equal to 50 nm.

Lithium manganese phosphate nanoparticles and method for manufacturing same, carbon-coated lithium manganese phosphate nanoparticles, carbon-coated lithium manganese phosphate nanoparticle granulated body, and lithium ion cell

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Otsu, Japan

Eiichiro Tamaki