Preparation and electrochemical performance of spherical MnOx with high capacitance

A promising electrode material, MnO_x, was prepared by chemical precipitation method using MnSO₄?·?H₂O as manganese source and (NH₄)₂CO₃ as precipitant. The as-prepared manganese oxide was characterized by field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), and X-ray diffraction (XRD), respectively. The effects of reaction temperature and calcination temperature on the electrochemical properties of the electrode materials were investigated. The results show that MnO_x with a spherical morphology exhibits an excellent performance in the energy storage field. Under the optimal experimental conditions, the specific capacitance of pure MnO_x reaches up to 592 F g^?2 in the alkaline media when the current density is 5 mA cm^?2 over the potential window from ?0.3 to +0.4 V. The combination resistance and transfer resistance of MnO_x are 0.86 and 0.08 Ω, respectively. These findings make MnO_x a promising electrode material for electrochemical capacitors.