INVESTIGATION OF LITHIUM INTERCALATION IN NANOSTRUCTURED IRON AND MANGANESE OXIDES

摘要

Structural analyses of novel nanocrystalline cathode materials for rechargeable lithium batteries are presented here. A nanocrystalline iron oxide shows evidence of much larger single-phase intercalation capacity than the microcrystalline iron oxide, in the intial stages of discharge. Thereafter, two phase reaction occurs upon deeper discharge as observed via the presence of a single set of isosbestic points in XAS data. Also presented here is analysis of a nanocrystalline Li_2MnO_3-like compound, exhibiting surprising lithium intercalation behavior and capable of reversibly intercalating a very large amount of lithium ions. XAS and XRD investigations of this material highlights its similarity to the rock-salt monoclinic Li_2MnO_3. XAS data also shows evidence for occurrence of Faradaic reduction-oxidation processes in this material with excellent reversibility upon discharge-charge.