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°.

Abstract: A stroke simulator is configured in such a manner that an elastic member disposed in a cylinder of the stroke simulator is restricted from being deformed in a radial direction of the cylinder.

Abstract: A power tool includes a spindle, a housing, a cover body configured to be removably mounted to the housing, a first engagement part provided on or in the cover body, and a second engagement part provided on or in the housing. The cover body includes an upper plate part and an outer peripheral part. The second engagement part is movable between an engagement position and a disengagement position. The first and second engagement parts are configured to restrict rotation of the cover body around the drive axis relative to the housing by engaging with each other. The first engagement part is (i) at a same location as or radially outward of the outer peripheral part of the cover body in a radial direction orthogonal to the drive axis, and (ii) between an upper end and a lower end of the cover body in the up-down direction.

Abstract: A power tool has a motor, an output shaft, a spindle, a gear, a gear housing and a bearing. The spindle is configured to be rotated around a drive axis crossing an extending direction of the output shaft. The gear is fitted on the spindle and configured to transmit rotation of the output shaft to the spindle. The gear housing houses the spindle, the gear and the bearing with the lower end part of the spindle protruded downward. The bearing is arranged on the radially outer side of the gear and configured to support the spindle so as to be rotatable around the drive axis.

Abstract: 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.

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: In manufacturing a storage battery electrode, a method for manufacturing a storage battery electrode with high capacity and stability is provided. As a method for preventing a mixture for forming an active material layer from becoming strongly basic, a first aqueous solution is formed by mixing an active material exhibiting basicity with an aqueous solution exhibiting acidity and including an oxidized derivative of a first conductive additive; a first mixture is formed by reducing the oxidized derivative of the first conductive additive by drying the first aqueous solution; a second mixture is formed by mixing a second conductive additive and a binder; a third mixture is formed by mixing the first mixture and the second mixture; and a current collector is coated with the third mixture. The strong basicity of the mixture for forming an active material layer is lowered; thus, the binder can be prevented from becoming gelled.

Abstract: Provided is a positive electrode active material which suppresses a reduction in capacity due to charge and discharge cycles when used in a lithium ion secondary battery. A covering layer is formed by segregation on a superficial portion of the positive electrode active material. The positive electrode active material includes a first region and a second region. The first region exists in an inner portion of the positive electrode active material. The second region exists in a superficial portion of the positive electrode active material and part of the inner portion thereof. The first region includes lithium, a transition metal, and oxygen. The second region includes magnesium, fluorine, and oxygen.

Abstract: To increase capacity per weight of a power storage device, a particle includes a first region, a second region in contact with at least part of a surface of the first region and located on the outside of the first region, and a third region in contact with at least part of a surface of the second region and located on the outside of the second region. The first and the second regions contain lithium and oxygen. At least one of the first region and the second region contains manganese. At least one of the first and the second regions contains an element M. The first region contains a first crystal having a layered rock-salt structure. The second region contains a second crystal having a layered rock-salt structure. An orientation of the first crystal is different from an orientation of the second crystal.

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.

Abstract: Provided is a positive electrode active material which suppresses a reduction in capacity due to charge and discharge cycles when used in a lithium ion secondary battery. A covering layer is formed by segregation on a superficial portion of the positive electrode active material. The positive electrode active material includes a first region and a second region. The first region exists in an inner portion of the positive electrode active material. The second region exists in a superficial portion of the positive electrode active material and part of the inner portion thereof. The first region includes lithium, a transition metal, and oxygen. The second region includes magnesium, fluorine, and oxygen.

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.

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: 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.

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: 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.

Abstract: Provided is a positive electrode active material which suppresses a reduction in capacity due to charge and discharge cycles when used in a lithium ion secondary battery. A covering layer is formed by segregation on a superficial portion of the positive electrode active material. The positive electrode active material includes a first region and a second region. The first region exists in an inner portion of the positive electrode active material. The second region exists in a superficial portion of the positive electrode active material and part of the inner portion thereof. The first region includes lithium, a transition metal, and oxygen. The second region includes magnesium, fluorine, and oxygen.

Abstract: A novel electrode is provided. A novel power storage device is provided. A conductor having a sheet-like shape is provided. The conductor has a thickness of greater than or equal to 800 nm and less than or equal to 20 ?m. The area of the conductor is greater than or equal to 25 mm2 and less than or equal to 10 m2. The conductor includes carbon and oxygen. The conductor includes carbon at a concentration of higher than 80 atomic % and oxygen at a concentration of higher than or equal to 2 atomic % and lower than or equal to 20 atomic %.

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.

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.