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.

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.

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.

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.

Provided is a vapor-based heat transfer apparatus (e.g. a vapor chamber or a heat pipe), comprising: a hollow structure having a hollow chamber enclosed inside a sealed envelope or container made of a thermally conductive material, a wick structure in contact with one or a plurality of walls of the hollow structure, and a working liquid within the hollow structure and in contact with the wick structure, wherein the wick structure comprises a graphene material and the hollow structure walls comprise an evaporator wall having a first surface plane and a condenser wall having a second surface plane, wherein multiple sheets of the graphene material in the wick structure are aligned to be substantially parallel to one another and perpendicular to at least one of the first surface plane and the second surface plane. Also provided is a process for producing this apparatus.

Provided is a vapor-based heat transfer apparatus (e.g. a vapor chamber or a heat pipe), comprising: a hollow structure having a hollow chamber enclosed inside a sealed envelope or container made of a thermally conductive material, a wick structure in contact with one or a plurality of walls of the hollow structure, and a working liquid within the hollow structure and in contact with the wick structure, wherein the wick structure comprises a graphene material and the hollow structure walls comprise an evaporator wall having a first surface plane and a condenser wall having a second surface plane, wherein multiple sheets of the graphene material in the wick structure are aligned to be substantially parallel to one another and perpendicular to at least one of the first surface plane and the second surface plane. Also provided is a process for producing this apparatus.

The present invention relates to a method for preparing graphene oxide by cutting an end face of a 3-dimensional carbon-based material by electrochemical oxidation and the graphene oxide prepared by the method. The method comprises connecting a piece of a 3-dimensional carbon-based material as an electrode and another piece of a 3-dimensional carbon-based material or inert material as another electrode to the two electrodes of a DC power supply. A working face of one piece of 3-dimensional carbon-based material contacts the surface of an electrolyte solution, and the two pieces are electrified for electrolysis, during which the working face is between -5 mm below and 5 mm above the surface of the electrolyte solution. The graphite lamella on the end face of one piece of the 3 dimensional carbon-based material used as an electrode is expansion-exfoliated and cut into graphene oxide by electrochemical oxidation, to obtain a graphene oxide-containing electrolyte solution.

The present invention relates to a method for preparing graphene oxide by cutting an end face of a 3-dimensional carbon-based material by electrochemical oxidation and the graphene oxide prepared by the method. The method comprises connecting a piece of a 3-dimensional carbon-based material as an electrode and another piece of a 3-dimensional carbon-based material or inert material as another electrode to the two electrodes of a DC power supply. A working face of one piece of 3-dimensional carbon-based material contacts the surface of an electrolyte solution, and the two pieces are electrified for electrolysis, during which the working face is between -5 mm below and 5 mm above the surface of the electrolyte solution. The graphite lamella on the end face of one piece of the 3 dimensional carbon-based material used as an electrode is expansion-exfoliated and cut into graphene oxide by electrochemical oxidation, to obtain a graphene oxide-containing electrolyte solution.

Provided are a method for producing a graphite oxide derivative capable of simply producing a high-quality graphite oxide derivative, and a high-quality graphite oxide derivative. The present invention relates to a method for producing a graphite oxide derivative, the method including the steps of oxidizing graphite; and preparing a graphite oxide derivative by reacting graphite oxide in a reaction liquid containing graphite oxide obtained in the oxidation step or graphite oxide in a graphite oxide-containing composition that is separated from the reaction liquid with a compound reactive with an oxygen-containing functional group of the graphite oxide, the method not including the step of purifying and drying the graphite oxide-containing reaction liquid between the oxidation step and the graphite oxide derivative preparation step.

Provided are a method for producing a graphite oxide derivative capable of simply producing a high-quality graphite oxide derivative, and a high-quality graphite oxide derivative. The present invention relates to a method for producing a graphite oxide derivative, the method including the steps of oxidizing graphite; and preparing a graphite oxide derivative by reacting graphite oxide in a reaction liquid containing graphite oxide obtained in the oxidation step or graphite oxide in a graphite oxide-containing composition that is separated from the reaction liquid with a compound reactive with an oxygen-containing functional group of the graphite oxide, the method not including the step of purifying and drying the graphite oxide-containing reaction liquid between the oxidation step and the graphite oxide derivative preparation step.