Microstructure and electrochemical characterization of spherical-like orthorhombic LiMnO2 via co-precipitation

Spherical-like morphology orthorhombic LiMnO2 (So-LiMnO2) powders were prepared using spherical-like MnCO3 precursors, which were obtained by a carbonate co-precipitation method. The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) method. Non-spherical orthorhombic LiMnO2 (No-LiMnO2) powders were also studied and compared with the above-mentioned So-LiMnO2. The results show that the microstructure of o-LiMnO2 depends significantly on that of the precursors. The obtained So-LiMnO2 has a poor crystalline structure, more stacking faults and small crystallites that have morphology similar to that of powders consisting of larger particles. Benefiting from its unique microstructure, the So-LiMnO2 cathode exhibits a higher maximum capacity and better capacity retention compared to that of No-LiMnO2. The analyses performed with a transmission electron microscopy (TEM) and an energy dispersive spectroscopy (EDS), confirmed that So-LiMnO2 particle, formed by the agglomeration of primary particles, can reduce the erosion of positive material by electrolytes and the dissolution of manganese, which results in the enhanced electrochemical cycleability. (C) 2007 Elsevier B.V. All rights reserved.