| 摘要 |
[Problem] To provide a transition metal oxide containing solid-solution lithium capable of realizing high initial discharge capacity, high capacity retention rate, and a still higher average voltage. [Solution] The transition metal oxide containing solid-solution lithium: is represented by a compositional formula Li1.5[NiaCobMnc[Li]d]O3 (in the formula, Li, Ni, Co, Mn, and O represent lithium, nickel, cobalt, manganese, and oxygen, respectively; a, b, c, and d satisfy the relationships: 0.1 ≦̸ d < 0.4, a + b + c + d = 1.5, 1.1 < a + b + c ≦̸ 1.4, -2/3d + 0.4 < a < -2.5d + 1.15); has a layered structure portion and a portion which changes to a spinel structure due to a charge or a charge/discharge being performed in a prescribed potential range; and satisfies the relationship 4/3d + 1 / 15 ≦̸ k' ≦̸ 1 when 0.1 ≦̸ d ≦̸ 0.25, and the relationship 0.4 ≦̸ k' ≦̸ 1.0 when 0.25 < d < 0.4, where k' is an average value of k (calculated as an average value upon charging/discharging up to each of maximum voltages 4.5V, 4.6V, 4.7V, and 4.8V (relative to lithium metal) in the order stated), and k is the spinel structure change ratio of the transition metal oxide containing solid-solution lithium relative to the spinel structure change ratio when the layered structure of Li2MnO3 in the transition metal oxide containing solid-solution lithium completely changes to the spinel structure LiMn2O4 in the process. |
