Positive electrode active material particles for lithium ion secondary batteries, positive electrode using the same, and lithium ion secondary battery

Positive electrode active material particles for lithium ion secondary batteries, the particles each comprising:

• a core particle;
• and a shell layer attached to the surface of the core particle,
• wherein the core particle comprises a first olivine-structured, lithium-containing phosphate compound including:
• at least one metal element selected from the group consisting of Fe and Mn;
• and Li,
• the shell layer comprises a second olivine-structured, lithium-containing phosphate compound including:
• at least one metal element selected from the group consisting of Fe and Mn;
• and Li, at least the core particle includes a phosphorous compound represented by the following formula (1):
• MemPnOp (I)
• where Me is at least one metal element selected from the group consisting of Fe and Mn, 0<m≦3, 0<n≦3, and 0≦p≦5,
• a content C1 of the phosphorous compound relative to the total moles of the first olivine-structured, lithium-containing phosphate compound and the phosphorous compound in the core particle, is 0.5 to 3 mol %, and
• in the case where the shell layer includes the phosphorous compound represented by the formula (1), a content C2 of the phosphorous compound relative to the total moles of the second olivine-structured, lithium-containing phosphate compound and the phosphorous compound in the shell layer, is smaller than the content C1.