| abstract |
Provided are positive electrode active material particles with low degradation. An electrical storage device with less deterioration is provided. An electrical storage device with high safety is provided. Has a first grain, a second grain, and a grain boundary positioned between the first grain and the second grain, the first grain and the second grain having lithium, a transition metal, and oxygen, and the grain boundary being magnesium, oxygen And the ratio of the atomic concentration of magnesium at the grain boundary to the atomic concentration of the transition metal in the first grain and the second grain is positive electrode active material particles having a region of 0.010 or more and 0.50 or less. |