POSITIVE ELECTRODE ACTIVE MATERIAL FOR ALL-SOLID-STATE LITHIUM-ION BATTERY, ELECTRODE, AND ALL-SOLID-STATE LITHIUM-ION BATTERY

The present invention provides a positive electrode active material for an all-solid-state lithium-ion battery, an electrode, and an all-solid-state lithium-ion battery capable of smoothly exchanging lithium ions with a solid electrolyte at a positive electrode and improving battery performance. A positive electrode active material for an all-solid-state lithium-ion battery formed of particles includes crystals of a lithium metal composite oxide, in which the lithium metal composite oxide has a layered structure and contains at least Li and a transition metal, and the particles have an average crush strength of more than 50 MPa and satisfy Expression (1). 1.0 μm≤ (1)