Semiconductor Energy Laboratory Co., Ltd.

Hiroatsu Todoriki

Yumiko Saito

Junpei Momo

Kuniharu Nomoto

Takahiro Kawakami

Mikio Yukawa

Rie Matsubara

Teppei Oguni

Shunpei Yamazaki

Takeshi Osada

Nobuhiro Inoue

Masaki Yamakaji

Rika Yatabe

Yasuhiko Takemura

Tatsuya Ikenuma

The formation method of graphene includes the steps of forming a layer including graphene oxide over a first conductive layer; and supplying a potential at which the reduction reaction of the graphene oxide occurs to the first conductive layer in an electrolyte where the first conductive layer as a working electrode and a second conductive layer with a as a counter electrode are immersed. A manufacturing method of a power storage device including at least a positive electrode, a negative electrode, an electrolyte, and a separator includes a step of forming graphene for an active material layer of one of or both the positive electrode and the negative electrode by the formation method.

Graphene and power storage device, and manufacturing method thereof

A power storage device with high output is provided, in which the specific surface area is increased while keeping the easy-to-handle particle size of its active material. The power storage device includes a positive electrode including a positive electrode current collector and a positive electrode active material layer, a negative electrode including a negative electrode current collector and a negative electrode active material layer, and an electrolyte. The negative electrode active material layer includes a negative electrode active material which is a particle in which a plurality of slices of graphite is overlapped with each other with a gap therebetween. It is preferable that the grain diameter of the particle be 1 μm to 50 μm. Further, it is preferable that the electrolyte be in contact with the gap between the slices of graphite.

Power storage device

A power storage device with high output is provided, in which the specific surface area is increased while keeping the easy-to-handle particle size of its active material. The power storage device includes a positive electrode including a positive electrode current collector and a positive electrode active material layer, a negative electrode including a negative electrode current collector and a negative electrode active material layer, and an electrolyte. The negative electrode active material layer includes a negative electrode active material which is a particle in which a plurality of slices of graphite is overlapped with each other with a gap therebetween. It is preferable that the grain diameter of the particle be 1 &#x3bc;m to 50 &#x3bc;m. Further, it is preferable that the electrolyte be in contact with the gap between the slices of graphite.

To increase the conductivity and electric capacity of an electrode which includes active material particles and the like and is used in a battery, a graphene net including 1 to 100 graphene sheets is used instead of a conventionally used conduction auxiliary agent and binder. The graphene net which has a two-dimensional expansion and a three-dimensional structure is more likely to touch active material particles or another conduction auxiliary agent, thereby increasing the conductivity and the bonding strength between active material particles. This graphene net is obtained by mixing graphene oxide and active material particles and then heating the mixture in a vacuum or a reducing atmosphere.

Method of manufacturing electrode

A power storage device a positive electrode including a positive electrode active material layer and a negative electrode including a negative electrode active material layer. The positive electrode active material layer includes a plurality of particles of x[LiMnO]-(1&#x2212;x)[LiCoMnNiO] (obtained by assigning 0.5 to x, for example) which is a positive electrode active material, and multilayer graphene with which the plurality of particles of the positive electrode active material are at least partly connected to each other. In the multilayer graphene, a plurality of graphenes are stacked in a layered manner. The graphene contains a six-membered ring composed of carbon atoms, a poly-membered ring which is a seven or more-membered ring composed of carbon atoms, and an oxygen atom bonded to one or more of the carbon atoms in the six-membered ring and the poly-membered ring, which is a seven or more-membered ring.

Highly-pure graphite oxide, graphene oxide, or graphene is mass-produced. Graphite is oxidized by an oxidizer, so that a graphite oxide solution is obtained, and electrodialysis is performed on the graphite oxide solution to remove aqueous ions, whereby the purity of graphite oxide is increased. Graphene oxide manufactured using the graphite oxide is mixed with powder, and the mixture is reduced, whereby graphene exhibiting conductive properties is yielded and the powder can be bonded. Such graphene can be used instead of a conduction auxiliary agent or a binder of a variety of batteries.

Graphite oxide, graphene oxide or graphene, electric device using the same and method of manufacturing the same, and electrodialysis apparatus

To provide a positive electrode for a lithium-ion secondary battery, which is highly filled with a positive electrode active material and has a high-density positive electrode active material layer. To provide a lithium-ion secondary battery having high capacity and improved cycle characteristics with use of the positive electrode. After graphene oxide is dispersed in a dispersion medium, a positive electrode active material is added and mixed to form a mixture. A binder is added to the mixture and mixed to form a positive electrode paste. The positive electrode paste is applied to a positive electrode current collector and the dispersion medium contained in the positive electrode paste is evaporated, and then, the graphene oxide is reduced, so that a positive electrode active material layer containing graphene is formed over the positive electrode current collector.

Method for forming positive electrode for lithium-ion secondary battery

A power storage device with high output is provided, in which the specific surface area is increased while keeping the easy-to-handle particle size of its active material. The power storage device includes a positive electrode including a positive electrode current collector and a positive electrode active material layer, a negative electrode including a negative electrode current collector and a negative electrode active material layer, and an electrolyte. The negative electrode active material layer includes a negative electrode active material having a plurality of graphite particles. Each of the graphite particles consists of graphite layers that are overlapped with each other with a gap of 1 nm to 10 nm therebetween. It is preferable that the grain diameter of the particle be 1 &#x3bc;m to 50 &#x3bc;m. Further, the specific surface area of the particles is 20 m/g to 200 m/g.

A graphene oxide used as a raw material of a conductive additive for forming an active material layer with high electron conductivity with a small amount of a conductive additive is provided. A positive electrode for a nonaqueous secondary battery using the graphene oxide as a conductive additive is provided. The graphene oxide is used as a raw material of a conductive additive in a positive electrode for a nonaqueous secondary battery and, in the graphene oxide, the atomic ratio of oxygen to carbon is greater than or equal to 0.405.

Graphene oxide, positive electrode for nonaqueous secondary battery using graphene oxide, method of manufacturing positive electrode for nonaqueous secondary battery, nonaqueous secondary battery, and electronic device

A thin energy storage device having high capacity is obtained. An energy storage device having high output is obtained. A current collector and an active material layer are formed in the same manufacturing step. The number of manufacturing steps of an energy storage device is reduced. The manufacturing cost of an energy storage device is suppressed. One embodiment of the present invention relates to a method for manufacturing of an electric double layer capacitor, or a lithium ion capacitor, which includes porous metal electrodes formed by removing a metal from an alloy foil, and an electrolyte provided therebetween. A surface area per volume of the porous structure is greater than or equal to 100 m/cm.

Method for manufacturing a double layer capacitor and a lithium ion capacitor

An object is to recover metallic lithium from metallic lithium on which an unnecessary substance is formed without discarding the metallic lithium on which an unnecessary substance is formed. The present invention relates to a method for recovering metallic lithium in such a manner that metallic lithium on which a substance is formed is reacted with nitrogen to form lithium nitride; the lithium nitride is reacted with carbon dioxide to form lithium carbonate; the lithium carbonate is reacted with hydrochloric acid to form lithium chloride; the lithium chloride and potassium chloride are melted; and electrolysis is applied to the melted lithium chloride and potassium chloride.

Method for recovering metallic lithium

To provide a carbon-based negative electrode material which can be used with an electrolyte containing PC as a main ingredient, a carbon-based negative electrode material having a graphene layer structure is crystalline and has pores. That is, the crystal structure of the carbon-based negative electrode material is distorted more significantly than that of graphite. Accordingly, the carbon-based negative electrode material has a larger interlayer distance between graphenes than graphite. It has been shown that such a negative electrode material can be used for a secondary battery which contains an electrolyte containing PC as a main ingredient.

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Kanagawa, Japan

Hiroatsu Todoriki