The simple preparation of birnessite-type manganese oxide with flower-like microsphere morphology and its remarkable capacity retention

Birnessite-type manganese oxide with flower-like microsphere morphology and large specific surface area has been prepared by hydrothermal treating a mixture solution of KMnO4 and (NH4)2SO4 at 90 °C for 24 h. The obtained material is characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and N2 adsorption–desorption. Results indicate that the birnessite-type manganese oxide shows novel flower-like microsphere morphology and a specific surface area of 280 m2 g−1, and the flower-like microsphere consists of the thin nano-platelets. Electrochemical characterization indicates that the prepared material exhibits an ideal capacitive behavior with a capacitance value of 278 F g−1 in 1 mol L−1 Na2SO4 aqueous solution at a scan rate of 5 mV s−1. Moreover, the prepared manganese oxide electrode shows excellent cycle stability, and the specific capacitance can maintain 98.6% of the initial one after 5000 cycles.