Synthesis and Surface Coating of LiMn₂O₄ Nanorods for the Cathode of the Lithium-Ion Battery.

Abstract

MnO₂ nanorods are prepared using a hydrothermal method, and used as precursors for the synthesis of LiMn₂O₄ nanorod-based active material for the cathode of lithium-ion batteries. The effects of additives, pressure, reactant concentration in the solution, and reaction time during the hydrothermal synthesis on the morphology of MnO₂ are examined. For the synthesis of the LiMn₂O₄ nanorods, two synthetic methods, hydrothermal processing of the MnO₂ precursor in a Li-containing solution, and the solid-state reaction of the precursor with LiOH·H₂O powder are tested. The morphological and electrochemical properties of the resulting materials are then analyzed. The rate and cycle performances of the LiMn₂O₄ nanorods are considerably improved by a composite coating of Li-ion-conductive Li₂O-2B₂O₃ and electrically conductive carbon. Because the conductive properties of these coating materials can be obtained with low crystallinity of them, superior coating performance is attainable with relatively low-temperature of after heating, which is advantageous in preserving the morphology of LiMn₂O₄ nanorods.