The P2-type Na_2/3Fe_1/2Mn_1/2O₂ materials were synthesized by an ultrasonic spray pyrolysis followed by solid-state sintering method. The structures, morphologies and electrochemical performances of Na_2/3Fe_1/2Mn_1/2O₂ materials were characterized thoroughly by means of X-ray diffractometer, scanning electron microscope and electrochemical charge/discharge instruments. Moreover, a thin layer of Al₂O₃, which was formed on the surface of Na_2/3Fe_1/2Mn_1/2O₂, can enhance the storage performance by preventing the formation of Na₂CO₃·H₂O, which is believed to enhance the electrochemical performances of Na_2/3Fe_1/2Mn_1/2O₂ materials. This facile surface modification method may pave a way to synthesize advanced cathode materials for sodium-ion batteries.