Synthesis of novel Mn3O4 microsphere and its distinctive capacitance change during electrochemical cycling

► Mn3O4 microsphere with diameter about 2 µm and smooth surface has been prepared. ► The morphology of Mn3O4 microsphere is mainly controlled by adding oleic acid. ► Mn3O4 microsphere can be electrochemically oxidized to layered birnessite MnO2.