Characterization of Electrolytic Manganese Oxide Coating on Pt for Lithium Battery Applications

A novel method of electrolytically coating α/γ-manganese oxide on Pt was investigated in aqueous solution. Through cathodic polarization tests, three major reactions were verified: ( i ) (∼0.5 to 0.07 V), (0.07 to −0.6 V), and (−0.6 to −2.5 V). The coated specimens obtained at the third stage were further annealed and characterized by thermogravimetric-differential thermal analysis (TG-DTA), X-ray diffraction (XRD), scanning electron microscopy, and cyclic voltammetry. XRD and TG-DTA diagrams indicated that the coating film was it condensed into MnO at 450°C, oxidized into at 600°C, and finally transformed into at 900°C. The coated specimen (0.2 μm) revealing crumpled, nanosized flakes was used as the cathode of a lithium battery. Its specific capacity increased from 182 mAh/g for the first cycle to 209 mAh/g for the 10th cycle between 4.0 and 2.0 V; the crystalline stability also increased. The mixed phases and the nanocrumpled structures of the coated film were considered as the main factors resulting in the improved capacity and stability during cyclic lithium insertion and extraction.