Nonaqueous electrolyte secondary batteries

A nonaqueous electrolyte secondary battery comprising a positive electrode, a negative electrode and a nonaqueous electrolyte, wherein

• the positive electrode comprises a positive electrode active material that comprises:
• a secondary particle formed by aggregation of primary particles of a lithium transition metal oxide, and
• a secondary particle formed by aggregation of primary particles of a rare earth compound;
• on a surface of the secondary particle of the lithium transition metal oxide, the secondary particle of the rare earth compound is attached to a recess formed between adjacent primary particles of the lithium transition metal oxide in such a manner that the secondary particle of the rare earth compound is attached to each of the primary particles forming the recess;
• the lithium transition metal oxide includes magnesium dissolved therein;
• and
• the concentration of magnesium dissolved in a region that extends from the surface of the secondary particle of the lithium transition metal oxide to 20% of the particle size of the particle is higher than the concentration of magnesium dissolved in the particle except the region.