Abstract:
A positive electrode active material which can improve cycle characteristics of a secondary battery is provided. Two kinds of regions are provided in a superficial portion of a positive electrode active material such as lithium cobaltate which has a layered rock-salt crystal structure. The inner region is a non-stoichiometric compound containing a transition metal such as titanium, and the outer region is a compound of representative elements such as magnesium oxide. The two kinds of regions each have a rock-salt crystal structure. The inner layered rock-salt crystal structure and the two kinds of regions in the superficial portion are topotaxy; thus, a change of the crystal structure of the positive electrode active material generated by charging and discharging can be effectively suppressed. In addition, since the outer coating layer in contact with an electrolyte solution is the compound of representative elements which is chemically stable, the secondary battery having excellent cycle characteristics can be obtained.
Abstract:
A positive electrode active material which can improve cycle characteristics of a secondary battery is provided. Two kinds of regions are provided in a superficial portion of a positive electrode active material such as lithium cobaltate which has a layered rock-salt crystal structure. The inner region is a non-stoichiometric compound containing a transition metal such as titanium, and the outer region is a compound of representative elements such as magnesium oxide. The two kinds of regions each have a rock-salt crystal structure. The inner layered rock-salt crystal structure and the two kinds of regions in the superficial portion are topotaxy; thus, a change of the crystal structure of the positive electrode active material generated by charging and discharging can be effectively suppressed. In addition, since the outer coating layer in contact with an electrolyte solution is the compound of representative elements which is chemically stable, the secondary battery having excellent cycle characteristics can be obtained.
Abstract:
To provide a positive electrode active material with which the cycle performance of a secondary battery can be improved and a manufacturing method thereof. When a secondary battery is fabricated using, for a positive electrode, a positive electrode active material obtained by depositing a solid electrolyte on a lithium compound with the use of a graphene compound by spray-drying treatment and volatilizing carbon from the graphene compound by heat treatment, the decomposition of an electrolyte solution in contact with the positive electrode active material can be inhibited, contributing to improvement in the cycle performance of the secondary battery.
Abstract:
A light-emitting device having a curved light-emitting surface is provided. Further, a highly-reliable light-emitting device is provided. A substrate with plasticity is used. A light-emitting element is formed over the substrate in a flat state. The substrate provided with the light-emitting element is curved and put on a surface of a support having a curved surface. Then, a protective layer for protecting the light-emitting element is formed in the same state. Thus, a light-emitting device having a curved light-emitting surface, such as a lighting device or a display device can be manufactured.
Abstract:
Provided is a positive electrode active material for a lithium ion secondary battery having favorable cycle characteristics and high capacity. A covering layer containing aluminum and a covering layer containing magnesium are provided on a superficial portion of the positive electrode active material. The covering layer containing magnesium exists in a region closer to a particle surface than the covering layer containing aluminum is. The covering layer containing aluminum can be formed by a sol-gel method using an aluminum alkoxide. The covering layer containing magnesium can be formed as follows: magnesium and fluorine are mixed as a starting material and then subjected to heating after the sol-gel step, so that magnesium is segregated.
Abstract:
To increase the volume density or weight density of lithium ions that can be received and released in and from a positive electrode active material to achieve high capacity and high energy density of a secondary battery. A lithium manganese composite oxide represented by LixMnyMzOw that includes a region belonging to a space group C2/c and is covered with a carbon-containing layer is used as the positive electrode active material. The element M is an element other than lithium and manganese. The lithium manganese composite oxide has high structural stability and high capacity.
Abstract:
A novel element, a novel formation method of a film, or a novel formation method of an element is provided. Alternatively, a film including graphene is formed at low cost and high yield. A formation method of a film including graphene includes a first step of forming a film including graphene oxide that includes a first region and a second region by application of a dispersion liquid in which graphene oxide is dispersed over a substrate and removal of dispersion medium from the applied dispersion liquid, a second step of forming a film including graphene by light irradiation to the first region to reduce the first region, and a third step of removing the second region by washing.
Abstract:
To provide a method of manufacturing a lithium-ion secondary battery having stable charge characteristics and lifetime characteristics. A positive electrode is subjected to an electrochemical reaction in a large amount of electrolytic solution in advance before a secondary battery is completed. In this manner, the positive electrode can have stability. The use of the positive electrode enables manufacture of a highly reliable secondary battery. Similarly, a negative electrode is subjected to an electrochemical reaction in a large amount of electrolytic solution in advance. The use of the negative electrode enables manufacture of a highly reliable secondary battery.
Abstract:
A fabricating method and a fabricating apparatus for a lithium-ion secondary battery having stable charge characteristics and lifetime characteristics are provided. A positive electrode is subjected to an electrochemical reaction in a large amount of electrolyte solution in advance before a secondary battery is completed. In this manner, the positive electrode can have stability. In a manner similar to that of the positive electrode, a negative electrode is also subjected to the electrochemical reaction in a large amount of the electrolyte solution in advance, whereby a high reliable secondary battery can be manufactured.
Abstract:
One embodiment of the present invention is to provide a high-capacity lithium ion secondary battery and a production method thereof. To perform surface modification, a spherical resin is subjected to first heat treatment at a temperature higher than or equal to 500° C. in an inert atmosphere. By the heating, the contraction of a particle, the void formation due to a gas release from an inside of the particle, the crack on a particle surface, and the like are caused so as to form a support for sulfur that is to be mixed later. Obtained spherical particles and sulfur powder are mixed and then stored in a container. The mixture in the container is subjected to second heat treatment at a temperature higher than or equal to 120° C. without being exposed to outside air.