Positive electrode active material for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery
A positive electrode active material for a nonaqueous electrolyte secondary battery contains a lithium composite oxide particle as a main component, in which a ratio of Ni to a total number of moles of all metal elements other than Li is greater than 30 mol %. The lithium composite oxide particle includes a secondary particle being aggregation of primary particles having an average particle diameter of 1 μm or more, and a shell constituted around the secondary particle. A surface layer void is present between the secondary particle and the shell.
1. A positive electrode active material for a nonaqueous electrolyte secondary battery, comprising:
a lithium composite oxide particle as a main component, in which a ratio of Ni to a total number of moles of all metal elements other than Li is greater than 30 mol %,
wherein the lithium composite oxide particle includes a secondary particle being aggregation of primary particles having an average particle diameter of 1 μm or more and 15 μm or less, and a shell constituted around the secondary particle,
wherein the shell has a same composition as the secondary particle,
wherein a surface layer void is present between the secondary particle and the shell,
wherein the lithium composite oxide particle has voids constituted therein,
wherein the surface layer void is constituted within a range that extends from a surface of the lithium composite oxide particle by a length equal to 5% or less of a diameter of that particle, and
wherein the surface layer void constituted within a range that extends from a surface of the lithium composite oxide particle by a length equal to 5% or less of a diameter of that particle accounts for 10% or more of the voids.
2. The positive electrode active material according to claim 1 , wherein the lithium composite oxide particle has a volume-average particle diameter of 7 to 30 μm.
3. A nonaqueous electrolyte secondary battery comprising:
a positive electrode that includes the positive electrode active material;
a negative electrode; and
a nonaqueous electrolyte,
wherein the positive electrode active material for a nonaqueous electrolyte secondary battery includes
a lithium composite oxide particle as a main component, in which a ratio of Ni to a total number of moles of all metal elements other than Li is greater than 30 mol %,
wherein the lithium composite oxide particle includes a secondary particle being aggregation of primary particles having an average particle diameter of 1 μm or more and 15 μm or less, and a shell constituted around the secondary particle,
wherein the shell has a same composition as the secondary particle,
wherein a surface layer void is present between the secondary particle and the shell,
wherein the lithium composite oxide particle has voids constituted therein,
wherein the surface layer void is constituted within a range that extends from a surface of the lithium composite oxide particle by a length equal to 5% or less of a diameter of that particle, and
wherein the surface layer void constituted within a range that extends from a surface of the lithium composite oxide particle by a length equal to 5% or less of a diameter of that particle accounts for 10% or more of the voids.
4. The nonaqueous electrolyte secondary battery according to claim 3 , wherein the lithium composite oxide particle has a volume-average particle diameter of 7 to 30 μm.