POSITIVE ELECTRODE ACTIVE MATERIALS FOR ALL-SOLID-STATE RECHARGEABLE BATTERIES, PREPARATION METHODS THEREOF, AND ALL-SOLID-STATE RECHARGEABLE BATTERIES

A positive electrode active material for an all-solid-state rechargeable battery, a method of preparing the positive electrode active material, and an all-solid-state rechargeable battery including the positive electrode active material are provided. The positive electrode active material includes secondary particles each including a lithium transition metal-based composite oxide and formed by agglomerating a plurality of primary particles, wherein at least a portion of the primary particles is arranged radially in the secondary particle, a first coating layer on the surface of the secondary particle and containing boron, and a second coating layer on the first coating layer and including ZrOand LiZrO.