Toray Industries, Inc.

Takashi Konishi

Eiichiro Tamaki

Manabu Kawasaki

Koki Miyazono

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

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Otsu, Japan

Takashi Konishi