Facile synthesis and electrochemical characterization of hierarchical α-MnO2 spheres

Hierarchical alpha-MnO2 spheres have been synthesized by a facile wet chemical method involving no templates. The products were characterized by XRD, SEM, EDX, and TEM. It was found that the products are composed of a large quantity of submicron-spheres with diameters of 300-500 nm and a few microspheres with diameters of several micrometers. The MnO2 submicron-spheres were constructed of many small nanorods with diameters of ca. 10 nm and lengths up to 50 nm. The influences of experimental parameters on the morphology and phase of the products were investigated. The possible formation mechanism for the hierarchical alpha-MnO2 spheres was discussed based on the experimental results. Electrochemical properties of the as-synthesized MnO2 spheres as cathode materials in Li-ion cells were also studied and compared. (c) 2007 Elsevier B. V. All rights reserved.