Lithium storage using conversion reaction in maghemite and hematite

Abstract

We report here on the lithium storage performance of α - and γ -Fe2 O3, undergoing conversion reaction at C/10 and 2C. Both α - and γ -Fe2 O3 transform to nanostructured Fe/ Li2 O composite during the first discharge, while the first charge results in the formation of nanosized γ -Fe2 O3. Such a transition from α -Fe2 O3 to γ -Fe2 O3 is attributed to its thermodynamics at the nanosize. Better storage performance of γ -Fe2 O3 at 2C compared with α -Fe2 O3 is attributed to the formation of highly crystalline, nanosized γ -Fe2 O 3. Apart from the reported inherent electronic conductivity of α -Fe2 O3, the thermodynamics at the nanosize is also found to be one of the rate-limiting factors. © 2010 The Electrochemical Society.