Manganese spinel-type lithium transition metal oxide
Provided is a new 5 V class spinel exhibiting an operating potential of 4.5 V or more (5 V class), which can suppress the amount of gas generation during high temperature cycles. Suggested is a manganese spinel-type lithium transition metal oxide represented by formula: Li[Ni y Mn 2-(a+b)-y-z Li a Ti b M z ]O 4 (wherein 0≦z≦0.3, 0.3≦y<0.6, and M=at least one or more metal elements selected from the group consisting of Al, Mg, Fe and Co), in which in the above formula, the following relationships are satisfied: a>0, b>0, and 3≦b/a≦8.
1. A manganese spinel-type lithium transition metal oxide represented by formula: Li[Ni y Mn 2-(a+b)-y-z Li a Ti b M z ]O 4 , wherein 0≦z≦0.3, 0.3≦y<0.6, and M=at least one or more metal elements selected from the group consisting of Al, Mg, Fe and Co, having a crystal structure of space group Fd-3m, wherein in the above formula, the Ni y , Mn 2-(a+b)-y-z , Li a , Ti b and M z exist in 16d sites in the crystal structure of the space group Fd-3m, a molar ratio of Li (a) existing in the 16d sites is a>0, a molar ratio of Ti (b) existing in the 16d sites is b>0, a total molar ratio of Li, Ti, Ni, and M (a+b+y+z) existing in the 16d sites is 0.3<(a+b+y+z), and the molar ratio of Ti with respect to Li (b/a) existing in the 16d sites is 3≦b/a≦8, the manganese spinel-type lithium transition metal oxide exhibiting an operating potential of 4.5 V or more.
2. The manganese spinel-type lithium transition metal oxide according to claim 1 , wherein a lattice constant is 8.16 Å to 8.22 Å.
3. The manganese spinel-type lithium transition metal oxide according to claim 1 , wherein a specific surface area is 0.10 m 2 /g to 1.00 m 2 /g.
4. The manganese spinel-type lithium transition metal oxide according to claim 1 , wherein an oxygen occupancy rate that can be determined by a Rietveld analysis is 0.87 to 1.00.
5. A lithium secondary battery comprising the manganese spinel-type lithium transition metal oxide according to claim 1 as a positive electrode active material.
6. The manganese spinel-type lithium transition metal oxide according to claim 2 , wherein a specific surface area is 0.10 m 2 /g to 1.00 m 2 /g.
7. The manganese spinel-type lithium transition metal oxide according to claim 2 , wherein an oxygen occupancy rate that can be determined by a Rietveld analysis is 0.87 to 1.00.
8. The manganese spinel-type lithium transition metal oxide according to claim 3 , wherein an oxygen occupancy rate that can be determined by a Rietveld analysis is 0.87 to 1.00.
9. A lithium secondary battery comprising the manganese spinel-type lithium transition metal oxide according to claim 2 as a positive electrode active material.
10. A lithium secondary battery comprising the manganese spinel-type lithium transition metal oxide according to claim 3 as a positive electrode active material.
11. A lithium secondary battery comprising the manganese spinel-type lithium transition metal oxide according to claim 4 as a positive electrode active material.