AN INVESTIGATION OF SPINEL-RELATED AND ORTHORHOMBIC LIMNO2 CATHODES FOR RECHARGEABLE LITHIUM BATTERIES

Cathode materials that have been synthesized by reduction of lithium-m anganese-oxide and manganese-oxide precursors with hydrogen at 300 to 350-degrees-C, and with carbon at 600-degrees-C have been evaluated in rechargeable lithium cells. The cathodes which initially have a compo sition close to LiMnO2 contain structures related to the lithiated-spi nel phase Li2[Mn2]O4 and/or orthorhombic LiMnO2. The orthorhombic LiMn O2 component transforms gradually to a spinel structure on cycling. Th ese cathodes are significantly more tolerant to repeated lithium inser tion and extraction, when cycled over both the 4 and 3 V regions, than a standard Lix[Mn2]O4 spinel electrode (0 < x < 2).