Sn Doped MnO2 Electrode Material for Supercapacitors

Tin doped MnO2 was synthesized by chemical co-precipitation method to be used as an electrode material for supercapacitors. The morphology and structure of the products were characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and X-ray diffraction (XRD) spectrometry. Results showed that the products were made up of 200-500 nm spherical particles formed with 10 nm (diameter) by 100 nm (length) nanorods. And the crystallographic structure of MnO2 was the poorly crystallized delta-type. Cyclic voltammetry (CV), electrochemical impedance spectrometry (EIS), and galvanostatic charge-discharge tests indicated that the ratio of tin in the products had great effect on the electrochemical capacity. A specific capacitance of 293 F.g(-1) was obtained when the molar ratio of Mn to So was 50:1, which was 64.6% higher than that of the undoped material. After 600 charge-discharge cycles, the specific capacitance stabilized at 275 F.g(-1), exhibiting favorable capacitance retention ability.