An investigation of spinel-related and orthorhombic LiMn0₂ cathodes for rechargeable lithium batteries

Cathode materials that have been synthesized by reduction of lithium-manganese-oxide and manganese-oxide precursors with hydrogen at 300 to 350°C and with carbon at 600°C have been evaluated in rechargeable lithium cells. The cathodes which initially have a composition close to LiMnO₂ contain structures related to the lithiated-spinel phase Li₂[Mn₂]0₄ and/or orthorhombic LiMnO₂. The orthorhombic LiMnO₂ component transforms gradually to a spinel structure on cycling. These cathodes are significantly more tolerant to repeated lithium insertion and extraction, when cycled over both the 4 and 3 V regions, than a standard Liₓ[Mn₂]0₄ spinel electrode (0 < x < 2)