POSITIVE ELECTRODE ACTIVE MATERIAL, PREPARATION METHOD THEREOF, POSITIVE ELECTRODE PLATE, BATTERY, AND ELECTRIC DEVICE

A positive electrode active material, a preparation method thereof, a positive electrode plate, a battery, and an electric device are provided. The positive electrode active material includes a core and a coating layer. The core includes a sodium-ion transition metal oxide containing the iron element and/or nickel element. In the sodium-ion transition metal oxide, a molar amount of the iron element is denoted as b, a molar amount of the nickel is denoted as c, 0≤b≤0.4, and 0≤c≤0.4. The coating layer is disposed on at least a portion of a surface of the core, the coating layer contains an alkaline sodium compound, and based on a total mass of the positive electrode active material, a mass proportion of the alkaline sodium compound is w %, which satisfies: