POSITIVE ELECTRODE MATERIAL, ELECTROCHEMICAL DEVICE, AND ELECTRONIC DEVICE

A positive electrode material, including a lithium cobalt composite oxide, where the lithium cobalt composite oxide includes a matrix and a coating layer located on a surface of the matrix, the coating layer includes a first region and a second region, the first region has a Pmc crystal structure, the second region has an R-m crystal structure, and both the first region and the second region contain element Na. The positive electrode material of this application can reduce interface impedance during lithium-ion intercalation and deintercalation, improving high-temperature storage performance and cycling performance of the electrochemical device under high voltage.