Abstract: The positive electrode active material layer includes a plurality of particles of a positive electrode active material and a reaction mixture where reduced graphene oxide is bonded to a polymer having a functional group as a side chain. The reduced graphene oxide has a sheet-like shape and high conductivity and thus functions as a conductive additive by being in contact with the plurality of particles of the positive electrode active material. The reaction mixture serves as an excellent binder since the reduced graphene oxide is bonded to the polymer. Therefore, even a small amount of the reaction mixture where the reduced graphene oxide is covalently bonded to the polymer excellently serves as a conductive additive and a binder.

Abstract: A positive electrode for a nonaqueous secondary battery including an active material layer which has sufficient electron conductivity with a low ratio of a conductive additive is provided. A positive electrode for a nonaqueous secondary battery including an active material layer which is highly filled with an active material, id est, including the active material and a low ratio of a conductive additive. The active material layer includes a plurality of particles of an active material with a layered rock salt structure, graphene that is in surface contact with the plurality of particles of the active material, and a binder.

Abstract: A gel electrolyte and a separator are provided between the positive electrode current collector and the negative electrode current collector. The plurality of positive electrode current collectors and the plurality of negative electrode current collectors are stacked such that surfaces of negative electrodes with which active material layers are not coated or surfaces of positive electrodes with which active material layers are not coated are in contact with each other.

Abstract: A storage battery includes positive and negative electrodes and an electrolytic solution. The negative electrode includes a first element and carbon. The first element is any of silicon, tin, gallium, aluminum, germanium, lead, antimony, bismuth, silver, zinc, cadmium, and indium. The negative electrode includes an active material and a first layer in contact with a surface of the active material. The first layer has a thickness of 10 nm to 1000 nm inclusive. The electrolytic solution contains first and second cations. The first cation is one or more of a lithium ion, a sodium ion, a calcium ion, and a magnesium ion. The second cation is an imidazolium cation or a tertiary sulfonium cation.

Abstract: An aspect of the present invention is a nonaqueous electrolyte energy storage device including: a positive electrode including a positive active material layer of 5 mAh/cm2 or more in capacity density per unit area; a negative electrode including metallic lithium; and a nonaqueous electrolyte including an ionic liquid and a fluorinated ether.

Abstract: To provide a lithium-ion storage battery or electronic device that is flexible and highly safe. One embodiment of the present invention is a flexible storage battery including a positive electrode, a negative electrode, a separator between the positive electrode and the negative electrode, an exterior body that surrounds the positive electrode, the negative electrode, and the separator, and a wiring provided along the exterior body. At least part of the wiring is more easily breakable by deformation than the exterior body. The wiring is more vulnerable to deformation than the exterior body and thus damaged earlier than the exterior body. Damage to the wiring is detected and an alert is sent to a user; thus, the use of the storage battery can be stopped before the exterior body is damaged.

Abstract: A positive electrode for a nonaqueous secondary battery including an active material layer which has sufficient electron conductivity with a low ratio of a conductive additive is provided. A positive electrode for a nonaqueous secondary battery including an active material layer which is highly filled with an active material, id est, including the active material and a low ratio of a conductive additive. The active material layer includes a plurality of particles of an active material with a layered rock salt structure, graphene that is in surface contact with the plurality of particles of the active material, and a binder.

Abstract: An aspect of the present invention is a nonaqueous electrolyte energy storage device that includes a negative electrode including a lithium alloy and a nonaqueous electrolyte containing a fluorinated solvent, in which the lithium alloy contains silver, and the content of silver with respect to the total content of lithium and silver in the lithium alloy is 3% by mass or more and 20% by mass or less. Another aspect of the present invention is a nonaqueous electrolyte energy storage device that includes a negative electrode including a lithium alloy and a nonaqueous electrolyte including a lithium salt containing fluorine, in which the lithium alloy contains silver, and the content of silver with respect to the total content of lithium and silver in the lithium alloy is 3% by mass or more and 20% by mass or less.

Abstract: A positive electrode for a nonaqueous secondary battery including an active material layer which has sufficient electron conductivity with a low ratio of a conductive additive is provided. A positive electrode for a nonaqueous secondary battery including an active material layer which is highly filled with an active material, id est, including the active material and a low ratio of a conductive additive. The active material layer includes a plurality of particles of an active material with a layered rock salt structure, graphene that is in surface contact with the plurality of particles of the active material, and a binder.

Abstract: To provide a graphene compound having an insulating property and an affinity for lithium ions. To increase the molecular weight of a substituent included in a graphene compound. To provide a graphene compound including a chain group containing an ether bond or an ester bond. To provide a graphene compound including a substituent containing one or more branches. To provide a graphene compound including a substituent including at least one of an ester bond and an amide bond.

Abstract: To provide a manufacturing method of graphene oxide that allows mass production through a relatively simple process, at low costs, and with safety and efficiency. A hydrogen peroxide solution, sulfuric acid, and flake graphite are put in a reaction container, and the mixture is stirred to obtain expansion graphite. The synthesized expansion graphite is washed not with pure water but with a saturated aqueous solution of magnesium sulfate (MgSO4) or an organic solvent, whereby a large amount of sulfuric acid is contained between graphite layers. The expansion graphite is subjected to heat treatment or microwave irradiation to form expanded graphite, and a graphite layer is peeled by ultrasonic treatment and then oxidized to form a graphene compound.

Abstract: 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.

Abstract: A positive electrode for a secondary battery which enables both good battery characteristics and electrode strength at a predetermined level, a secondary battery, and a method for fabricating the positive electrode for a secondary battery are provided. The positive electrode for a secondary battery includes a current collector and an active material layer over the current collector. The active material layer includes an active material, graphene, and a binder. A carbon layer is on a surface of the active material. The proportion of the graphene in the active material layer is greater than or equal to 0.1 wt % and less than or equal to 1.0 wt %.

Abstract: A gel electrolyte and a separator are provided between the positive electrode current collector and the negative electrode current collector. The plurality of positive electrode current collectors and the plurality of negative electrode current collectors are stacked such that surfaces of negative electrodes with which active material layers are not coated or surfaces of positive electrodes with which active material layers are not coated are in contact with each other.

Abstract: A gel electrolyte and a separator are provided between the positive electrode current collector and the negative electrode current collector. The plurality of positive electrode current collectors and the plurality of negative electrode current collectors are stacked such that surfaces of negative electrodes with which active material layers are not coated or surfaces of positive electrodes with which active material layers are not coated are in contact with each other.

Abstract: A positive electrode for a secondary battery which enables both good battery characteristics and electrode strength at a predetermined level, a secondary battery, and a method for fabricating the positive electrode for a secondary battery are provided. The positive electrode for a secondary battery includes a current collector and an active material layer over the current collector. The active material layer includes an active material, graphene, and a binder. A carbon layer is on a surface of the active material. The proportion of the graphene in the active material layer is greater than or equal to 0.1 wt % and less than or equal to 1.0 wt %.

Abstract: To provide a lithium-ion storage battery or electronic device that is flexible and highly safe. One embodiment of the present invention is a flexible storage battery including a positive electrode, a negative electrode, a separator between the positive electrode and the negative electrode, an exterior body that surrounds the positive electrode, the negative electrode, and the separator, and a wiring provided along the exterior body. At least part of the wiring is more easily breakable by deformation than the exterior body. The wiring is more vulnerable to deformation than the exterior body and thus damaged earlier than the exterior body. Damage to the wiring is detected and an alert is sent to a user; thus, the use of the storage battery can be stopped before the exterior body is damaged.

Abstract: To provide a manufacturing method of graphene oxide that allows mass production through a relatively simple process, at low costs, and with safety and efficiency. A hydrogen peroxide solution, sulfuric acid, and flake graphite are put in a reaction container, and the mixture is stirred to obtain expansion graphite. The synthesized expansion graphite is washed not with pure water but with a saturated aqueous solution of magnesium sulfate (MgSO4) or an organic solvent, whereby a large amount of sulfuric acid is contained between graphite layers. The expansion graphite is subjected to heat treatment or microwave irradiation to form expanded graphite, and a graphite layer is peeled by ultrasonic treatment and then oxidized to form a graphene compound.

Abstract: The positive electrode active material layer includes a plurality of particles of a positive electrode active material and a reaction mixture where reduced graphene oxide is bonded to a polymer having a functional group as a side chain. The reduced graphene oxide has a sheet-like shape and high conductivity and thus functions as a conductive additive by being in contact with the plurality of particles of the positive electrode active material. The reaction mixture serves as an excellent binder since the reduced graphene oxide is bonded to the polymer. Therefore, even a small amount of the reaction mixture where the reduced graphene oxide is covalently bonded to the polymer excellently serves as a conductive additive and a binder.

Abstract: An object is to improve the characteristics of a power storage device such as a charging and discharging rate or a charge and discharge capacity. The grain size of particles of a positive electrode active material is nano-sized so that a surface area per unit mass of the active material is increased. Specifically, the grain size is set to greater than or equal to 10 nm and less than or equal to 100 nm, preferably greater than or equal to 20 nm and less than or equal to 60 nm. Alternatively, the surface area per unit mass is set to 10 m2/g or more, preferably 20 m2/g or more, further, the crystallinity of the active material is increased by setting an XRD half width to greater than or equal to 0.12° and less than 0.17°, preferably greater than or equal to 0.13° and less than 0.16°.