CPC H01M 4/466 (2013.01) [C01G 51/42 (2013.01); H01M 4/131 (2013.01); H01M 4/1391 (2013.01); H01M 4/366 (2013.01); H01M 4/525 (2013.01); H01M 4/62 (2013.01); H01M 4/625 (2013.01); H01M 10/0525 (2013.01); C01P 2002/00 (2013.01); C01P 2002/85 (2013.01); C01P 2004/04 (2013.01); C01P 2006/40 (2013.01); G01N 23/2273 (2013.01); H01M 2004/028 (2013.01)] | 5 Claims |
1. A lithium-ion secondary battery comprising:
a positive electrode comprising a positive electrode active material,
wherein the positive electrode active material comprises a first region, a second region, and a third region,
wherein the first region comprises a layered rock-salt crystal structure,
wherein the third region comprises a rock-salt crystal structure,
wherein the second region covers at least a part of the first region,
wherein the third region covers at least a part of the second region,
wherein at least the part of the second region covered by the third region comprises a layered rock-salt crystal structure,
wherein the first region comprises lithium cobaltate,
wherein the second region comprises aluminum and oxygen,
wherein the third region comprises magnesium and oxygen,
wherein a crystal orientation of the rock-salt crystal structure of the third region is substantially aligned with a crystal orientation of the layered rock-salt crystal structure of at least the part of the second region covered by the third region,
wherein the positive electrode active material includes a crystal defect in the positive electrode active material, the crystal defect being observable from a TEM image,
wherein the crystal defect includes magnesium, and
wherein a distribution of aluminum comprises a region existing deeper from a surface of the positive electrode active material than a distribution of magnesium, and
wherein the positive electrode active material is free of at least one of intentionally added nickel and manganese.
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