A positive electrode material includes secondary particles formed from primary particles. The positive electrode material satisfies the following relational expression: 15%≤(Dv50a−Dv50b)/Dv50b≤80%, where Dv50a represents Dv50 directly measured by a laser particle size analyzer for the positive electrode material without ultrasonic treatment, Dv50b represents Dv50 measured by the laser particle size analyzer for the positive electrode material after ultrasonic treatment, and Dv50 represents a particle size of the positive electrode material at a cumulative volume of 50% in a volume-based particle size distribution as measured by starting from small particle sizes. The secondary particles of the positive electrode material that meets the foregoing condition can form soft agglomerates, so that the electrochemical device is of high cycle performance and high safety performance.