| 摘要 |
Provided is cathode active material powder or a cathode that is capable of improving the cycle characteristics of nonaqueous electrolyte rechargeable batteries at high voltage and exhibiting excellent capacity retention. The cathode active material powder has a composition of formula (I) : Li x_w Na w Co 1- yM y O 2+z ‰¤ ‰¤ x ‰¤ 1.100, 0 < y ‰¤ 0.050, -0.1 ‰¤ z ‰¤ 0.1, 0 ‰¤ w ‰¤ 0.020; M: rare earth elements, Ti, Zr, Mo, Mn, Ni, Cu, Al, Ga, etc.), and a core-shell structure composed of a lithium-containing composite oxide region as a core and a Li-ion-conductive oxide region as a shell, wherein the core contains Li, Co, and oxygen, and has the Co concentration of not higher than 90 % as calculated by formula (II): ((Co concentration on shell external surface) / (Co concentration at shell boundary of core/shell structure)) × 100, and wherein the shell is an amorphous layer containing La, Ti, Co, and oxygen, covering the core at least partly. |
