Lithium manganese composite oxide, secondary battery, and electrical device
The volume density or weight density of lithium ions that can be received and released in and from a positive electrode active material is increased to achieve high capacity and high energy density of a secondary battery. In a lithium manganese composite oxide, each particle includes a first region including a crystal with a layered rock-salt crystal structure and a second region including a crystal with a spinel crystal structure. The second region is in contact with the outside of the first region. The lithium manganese composite oxide has high structural stability and high capacity.
1. A lithium manganese composite oxide comprising:
a particle comprising a first region including a crystal with a layered rock-salt structure and a second region including a crystal with a spinel structure,
wherein the second region is in contact with the first region,
wherein the second region covers 10% or more of an entire outside surface of the first region,
wherein the layered rock-salt structure is represented by Li r Mn s-t M t O 3 ,
wherein 1.4≦r≦2, 0.7≦s<1.5, 0≦t<1.5, and s≧t are satisfied, and
wherein an element M is silicon, phosphorus, or a metal element other than lithium and manganese.
2. A lithium manganese composite oxide comprising:
a crystal region with a spinel structure on at least part of a surface of a particle including a crystal region with a layered rock-salt structure,
wherein the crystal region with the spinel structure covers 10% or more of an entire surface of the particle,
wherein the layered rock-salt structure is represented by Li r Mn s-t M t O 3 ,
wherein 1.4≦r≦2, 0.7≦s<1.5, 0≦t<1.5, and s≧t are satisfied, and
wherein an element M is silicon, phosphorus, or a metal element other than lithium and manganese.
3. A lithium manganese composite oxide comprising:
a particle comprising a first region including a crystal with a layered rock-salt structure and a second region essentially consisting of a crystal with a spinel structure,
wherein the particle has the second region on at least part of a surface thereof,
wherein the second region includes a layered region,
wherein the layered rock-salt structure is represented by Li r Mn s-t M t O 3 ,
wherein 1.4≦r≦2, 0.7≦s<1.5, 0≦t<1.5, and s≧t are satisfied, and
wherein an element M is silicon, phosphorus, or a metal element other than lithium and manganese.
4. The lithium manganese composite oxide according to claim 1 , wherein the second region covers 30% or more of the entire outside surface of the first region.
5. A lithium-ion secondary battery comprising the lithium manganese composite oxide according to claim 1 as a positive electrode active material.
6. An electrical device comprising the lithium-ion secondary battery according to claim 5 .
7. The lithium manganese composite oxide according to claim 2 , wherein the crystal with the spinel structure covers 30% or more of the entire surface of the particle.
8. A lithium-ion secondary battery comprising the lithium manganese composite oxide according to claim 2 as a positive electrode active material.
9. An electrical device comprising the lithium-ion secondary battery according to claim 8 .
10. The lithium manganese composite oxide according to claim 3 , wherein the second region covers 30% or more of an entire outside surface of the first region.
11. A lithium-ion secondary battery comprising the lithium manganese composite oxide according to claim 3 as a positive electrode active material.
12. An electrical device comprising the lithium-ion secondary battery according to claim 11 .
13. A lithium manganese composite oxide comprising:
a particle comprising a first region including a crystal with a layered rock-salt structure and a second region including a crystal with a spinel structure,
wherein 10% or more of an entire outer surface of the particle is formed with a layered region having the spinel structure,
wherein the layered rock-salt structure is represented by Li r Mn s-t M t O 3 ,
wherein 1.4≦r≦2, 0.7≦s<1.5, 0≦t<1.5, and s≧t are satisfied, and
wherein an element M is silicon, phosphorus, or a metal element other than lithium and manganese.
14. A lithium-ion secondary battery comprising the lithium manganese composite oxide according to claim 13 as a positive electrode active material.
15. An electrical device comprising the lithium-ion secondary battery according to claim 14 .
16. The lithium manganese composite oxide according to claim 13 , wherein a thickness of the layered region is greater than or equal to 1 nm.
17. The lithium manganese composite oxide according to claim 3 , wherein a thickness of the layered region is greater than or equal to 1 nm.