Abstract: A positive electrode active material, which has a high capacity and excellent charge and discharge cycle performance, for a lithium-ion secondary battery is provided. Alternatively, a positive electrode active material that inhibits a decrease in capacity in charge and discharge cycles when used in a lithium-ion secondary battery is provided. Alternatively, a high-capacity secondary battery is provided. Alternatively, a highly safe or reliable secondary battery is provided. The positive electrode active material contains a first substance including a first crack and a second substance positioned inside the first crack. The first substance contains one or more of cobalt, manganese, and nickel, lithium, oxygen, magnesium, and fluorine. The second substance contains phosphorus and oxygen.

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: Provided is a positive electrode active material that achieves improvement in load resistance such as rate performance and output resistance when used as a positive electrode active material in a lithium-ion secondary battery, achieves improvement in powder properties, has a short manufacturing cycle time, and is low in cost. The positive electrode active material is manufactured by a first step of forming a first mixture by separately pulverizing a compound containing one or more elements selected from magnesium, calcium, zirconium, lanthanum, and barium; a compound containing halogen and an alkali metal; and a fluoride containing one or more metals selected from nickel, aluminum, manganese, titanium, vanadium, iron, and chromium, and then mixing them with metal oxide powder; and a second step of performing heating at a temperature higher than or equal to 700° C. and lower than or equal to 950° C.

Abstract: An object is to provide a method for manufacturing a positive electrode active material that achieves high powder properties and high load resistance (e.g., rate performance and output resistance) when used in a lithium-ion secondary battery, within a short manufacturing cycle time and at low cost. To perform heat treatment at temperatures lower than the melting point of magnesium fluorine, lithium fluoride is mixed to melt magnesium fluorine and modify the surface of lithium cobalt oxide powder. By mixing lithium fluoride, magnesium fluorine can be melted at a temperature lower than its melting point, and a positive electrode active material is formed utilizing this eutectic phenomenon.

Abstract: A positive electrode active material, which has a high capacity and excellent charge and discharge cycle performance, for a lithium-ion secondary battery is provided. Alternatively, a positive electrode active material that inhibits a decrease in capacity in charge and discharge cycles when used in a lithium-ion secondary battery is provided. Alternatively, a high-capacity secondary battery is provided. Alternatively, a highly safe or reliable secondary battery is provided. The positive electrode active material contains a first substance including a first crack and a second substance positioned inside the first crack. The first substance contains one or more of cobalt, manganese, and nickel, lithium, oxygen, magnesium, and fluorine. The second substance contains phosphorus and oxygen.

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.