Abstract: A novel method for forming a positive electrode active material is provided. In the method for forming a positive electrode active material, a cobalt source and an additive element source are mixed to form an acidic solution; the acidic solution and an alkaline solution are made to react to form a cobalt compound; the cobalt compound and a lithium source are mixed to form a mixture; and the mixture is heated. The additive element source is a compound containing one or more selected from gallium, aluminum, boron, nickel, and indium.

Abstract: A positive electrode active material with high charge and discharge capacity is provided. A novel positive electrode active material is provided. The positive electrode active material is manufactured in such a manner that after a cobalt compound (also referred to as a precursor) containing nickel, cobalt, and manganese is obtained by a coprecipitation method, a mixture obtained by mixing a lithium compound and the cobalt compound is heated at a first temperature; after the mixture is ground or crushed, heating at a second temperature that is a temperature higher than the first temperature is further performed; and after an additive is mixed, third heat treatment is performed. The first temperature is higher than or equal to 400° C. and lower than or equal to 700° C. The second temperature is higher than 700° C. and lower than or equal to 1050° C.

Abstract: A novel method for forming a positive electrode active material is provided. The method for forming a positive electrode active material includes causing a reaction between a cobalt aqueous solution and an alkaline aqueous solution to form a cobalt compound; mixing the cobalt compound and a lithium compound and performing a first heat treatment to form a first composite oxide; mixing the first composite oxide and a compound containing a first additive element and performing a second heat treatment to form a second composite oxide; and mixing the second composite oxide and a compound containing a second additive element and performing a third heat treatment. The first heat treatment is performed at a temperature higher than or equal to 700° C. and lower than or equal to 1100° C. The second heat treatment is performed at a temperature higher than or equal to 700° C. and lower than or equal to 1000° C.

Abstract: A secondary battery and a positive electrode active material each having high energy density per weight and per volume are provided. The secondary battery includes a positive electrode, the positive electrode includes lithium cobalt oxide, and the lithium cobalt oxide has a projection containing at least one or two or more selected from Hf, V, Nb, Ce, and Sm. The projection may further contain Mg, F, Ni, or Al as an additive element. The secondary battery is manufactured through a step of forming a mixed solution by mixing the lithium cobalt oxide and a metal alkoxide containing one or two or more selected from Hf, V, Nb, Ce, and Sm. With such a positive electrode active material, a secondary battery with a high charge voltage can be provided.

Abstract: A positive electrode active material having a crystal structure that is unlikely to be broken by repeated charging and discharging is provided. A positive electrode active material with high charge and discharge capacity is provided. A projection is provided on the surface of the positive electrode active material. The projection preferably contains zirconium and yttrium and is a rectangular solid. The projection preferably has a crystal structure that is tetragonal, cubic, or a mixture of two phases, tetragonal and cubic. In the positive electrode active material, the transition metal is one or two or more selected from cobalt, nickel, and manganese, and the additive elements are at least two or more selected from magnesium, fluorine, aluminum, zirconium, and yttrium.

Abstract: A manufacturing method of a highly purified positive electrode active material is provided. Alternatively, a manufacturing method of a positive electrode active material whose crystal structure is not easily broken even when charging and discharging are repeated is provided. Provided is a manufacturing method of a positive electrode active material containing lithium and a transition metal. The manufacturing method includes a first step of forming a hydroxide containing the transition metal using a basic aqueous solution and an aqueous solution containing the transition metal, a second step of preparing a lithium compound, a third step of mixing the lithium compound and the hydroxide to form a mixture, and a fourth step of heating the mixture to form a composite oxide containing lithium and the transition metal. A material with a purity higher than or equal to 99.

Abstract: According to one embodiment of the present invention, a positive electrode active material with high charge and discharge capacity is provided. Alternatively, a positive electrode active material with high charge and discharge voltage is provided. Alternatively, a positive electrode active material with little deterioration is provided. To improve the reliability of the positive electrode active material, the surface of the positive electrode active material is prevented from reacting with an electrolyte solution and being reduced. The provision of a projection on part of the positive electrode active material surface decreases the reduction of the positive electrode active material surface from reacting with the electrolyte solution, thereby improving the cycle performance.

Abstract: A highly convenient electronic device used while being worn on a body is provided. The electronic device is an arm-worn electronic device including a display panel, a power storage device, a circuit, and a sealing structure. The display panel displays an image with power supplied from the power storage device. The circuit includes an antenna and charges the power storage device wirelessly. Inside the sealing structure, the display panel, the power storage device, and the circuit are provided. The sealing structure includes a portion that transmits visible light. The sealing structure can be worn on an arm or is connected to a structure body that can be worn on an arm.

Abstract: A novel method for manufacturing a positive electrode active material is provided. In the method, an acid solution is formed by mixing an aqueous solution containing nickel, cobalt, and manganese with an aqueous solution containing a first additive element; a composite hydroxide containing nickel, cobalt, manganese, and the first additive element is formed by a reaction between the acid solution and an alkaline solution; the composite hydroxide and a lithium source are mixed and heated (first heating) to form a composite oxide; and the composite oxide and a second additive element source are mixed and heated (second heating). The first additive element is at least one of gallium, boron, aluminum, indium, magnesium, and fluorine, and the second additive element is at least one of calcium, gallium, boron, aluminum, indium, magnesium, and fluorine.

Abstract: A highly convenient electronic device used while being worn on a body is provided. The electronic device is an arm-worn electronic device including a display panel, a power storage device, a circuit, and a sealing structure. The display panel displays an image with power supplied from the power storage device. The circuit includes an antenna and charges the power storage device wirelessly. Inside the sealing structure, the display panel, the power storage device, and the circuit are provided. The sealing structure includes a portion that transmits visible light. The sealing structure can be worn on an arm or is connected to a structure body that can be worn on an arm.

Abstract: To provide a positive electrode active material with high charge and discharge capacity, or a novel positive electrode active material. The positive electrode active material is formed in the following manner: a cobalt compound (also referred to as a precursor) containing nickel, cobalt, and manganese is obtained by a coprecipitation method; a mixture obtained by mixing a lithium compound, the cobalt compound, and an additive is heated at first heating temperature; and the heated mixture is ground or crushed and further heated at second heating temperature that is higher than the first heating temperature. The first heating temperature is higher than or equal to 400° C. and lower than or equal to 700° C. The second heating temperature is higher than 700° C. and lower than or equal to 1050° C.

Abstract: The present invention relates to a method for manufacturing a secondary battery and a secondary battery. A method for manufacturing a positive electrode active material with high charge and discharge capacity is provided. A method for manufacturing a positive electrode active material with high charging and discharging voltages is provided. A method for manufacturing a positive electrode active material with little deterioration is provided. The positive electrode active material is manufactured through a step of forming a composite oxide that contains lithium, nickel, manganese, cobalt, and oxygen; and a step of mixing the composite oxide and a calcium compound, and then heating the mixture at a temperature higher than or equal to 500° C. and lower than or equal to 1100° C. for 2 hours to 20 hours. By the heating, calcium is distributed at a preferred concentration in a surface portion of the positive electrode active material.

Abstract: To provide a light-emitting device capable of being used in a wide temperature range. To provide a light-emitting device capable of being used in a low-temperature environment and a high-temperature environment. The light-emitting device includes a light-emitting panel, a secondary battery, a circuit, and a sealing structure. The light-emitting panel includes a light-emitting element. The light-emitting element can emit light with power supplied from the secondary battery. The circuit includes an antenna and can charge the secondary battery wirelessly. The light-emitting panel, the secondary battery, and the circuit are provided in the sealing structure. The sealing structure includes a portion through which light emitted from the light-emitting element passes.

Abstract: To provide a display device that is suitable for increasing in size. To provide a display device in which display unevenness is suppressed. To provide a display device that can display an image along a curved surface. The display device includes two display panels, two plates, two stages, two driver circuits, two adjusting units, and a frame. Each display panel includes a display portion, an operating circuit portion, a terminal, an external electrode, a transparent portion, and a first portion and has flexibility. Each transparent portion includes a region transmitting visible light. The display panels are fixed so that transparent portions and parts of the display portions extend beyond the plates. The display portion of one of the two display panels overlaps with the transparent portion of the other display panel.

Abstract: A highly convenient electronic device used while being worn on a body is provided. The electronic device is an arm-worn electronic device including a display panel, a power storage device, a circuit, and a sealing structure. The display panel displays an image with power supplied from the power storage device. The circuit includes an antenna and charges the power storage device wirelessly. Inside the sealing structure, the display panel, the power storage device, and the circuit are provided. The sealing structure includes a portion that transmits visible light. The sealing structure can be worn on an arm or is connected to a structure body that can be worn on an arm.

Abstract: A highly convenient electronic device used while being worn on a body is provided. The electronic device is an arm-worn electronic device including a display panel, a power storage device, a circuit, and a sealing structure. The display panel displays an image with power supplied from the power storage device. The circuit includes an antenna and charges the power storage device wirelessly. Inside the sealing structure, the display panel, the power storage device, and the circuit are provided. The sealing structure includes a portion that transmits visible light. The sealing structure can be worn on an arm or is connected to a structure body that can be worn on an arm.

Abstract: A charging control device using machine learning is provided. A high-security charging control device is provided. A charging control system with little deterioration is provided. A storage battery having excellent characteristics is provided. An approximate charging end time is calculated. A result obtained when it is different from the estimated charging end time is fed back and learned, and accordingly the charging end can be precisely estimated after the next time. That is, the portable information terminal makes a charging plan with the use of artificial intelligence and the secondary battery is charged based on information about the charging plan. The charging plan is made to reduce the retention time of the full charging (SOC 100%) and charging is executed. Charging history information is stored in the portable information terminal and made use of to make the next charging plan.

Abstract: An imaging system using ultraviolet light or a manufacturing apparatus including the imaging system is provided. An imaging system includes an imaging element and a light source, which operates the imaging element with light that is emitted from the light source and reflected or transmitted by an object. A pixel included in the imaging element includes a photoelectric conversion element and a charge holding part. The light source has a function of emitting ultraviolet light to an object. The photoelectric conversion element is irradiated with the ultraviolet light reflected or transmitted by the object. The photoelectric conversion element has a function of changing the potential of the charge holding part when irradiated with the ultraviolet light and retaining the potential when not irradiated with the ultraviolet light.

Abstract: To provide a display device that is suitable for increasing in size. To provide a display device in which display unevenness is suppressed. To provide a display device that can display an image along a curved surface. The display device includes two display panels, two plates, two stages, two driver circuits, two adjusting units, and a frame. Each display panel includes a display portion, an operating circuit portion, a terminal, an external electrode, a transparent portion, and a first portion and has flexibility. Each transparent portion includes a region transmitting visible light. The display panels are fixed so that transparent portions and parts of the display portions extend beyond the plates. The display portion of one of the two display panels overlaps with the transparent portion of the other display panel.

Abstract: To provide a display device that is suitable for increasing in size. To provide a display device in which display unevenness is suppressed. To provide a display device that can display an image along a curved surface. The display device includes two display panels, two plates, two stages, two driver circuits, two adjusting units, and a frame. Each display panel includes a display portion, an operating circuit portion, a terminal, an external electrode, a transparent portion, and a first portion and has flexibility. Each transparent portion includes a region transmitting visible light. The display panels are fixed so that transparent portions and parts of the display portions extend beyond the plates. The display portion of one of the two display panels overlaps with the transparent portion of the other display panel.