Rechargeable zinc-air battery showslow cost, high safety and high theoretical power/energydensity, which is one of the most promising energy technologies for future energy storage and power battery. Nevertheless, the energy efficiency is greatly limited by the slow kinetics of oxygen reduction reaction/oxygen evolution reaction (ORR/OER) on the cathode. In this work, different morphological MnO2catalysts with high surface areas were synthesized by mild hydrothermalcalcined processes.Their morphology, crystal structure and specific surface areawere obtained and furtheranalyzed by SEM, XRD, nitrogen adsorption and desorptiontests. The results show that the MnO2 nanoparticles with 50 nm exhibits higher catalytic activitiesthanother morphological MnO2 catalysts. In addition, the MnO2 nanoparticleswith 50 nm shows higher power density (229 mW cm-2 ) and more stable charge-discharge performance with low voltage drop (0.82 V for 100 h) than that of noble metal catalyst (Pt/C+ RuO2). This work provides a new idea for the development and application of MnO2-based bifunctional catalysts

Keywords : Morphology engineering, MnO2, bifunctional catalyst, zinc-air battery.