POSITIVE ELECTRODE MATERIAL, BATTERY, AND METHOD FOR PREPARING POSITIVE ELECTRODE MATERIAL

The positive electrode active material of the present disclosure includes a complex oxide represented by a formula (1): LiNiMeO as a main component and contains water generated during heating at 300°C in Karl Fischer titration in an amount of 317.5 ppm by mass or less. Here, x satisfies 0.5 ≤ x ≤ 1, and Me is at least one element selected from the group consisting of Mn, Co, and Al.