INVESTIGATION OF LITHIUM INTERCALATION IN NANOSTRUCTUREDIRON AND MANGANESE OXIDES

摘要

Structural analyses of novel nanocrystalline cathode materials forrechargeable lithium batteries are presented here. A nanocrystalline ironoxide shows evidence of much larger single-phase intercalation capacitythan the microcrystalline iron oxide, in the intial stages of discharge.Thereafter, two phase reaction occurs upon deeper discharge as observedvia the presence of a single set of isosbestic points in XAS data. Alsopresented here is analysis of a nanocrystalline Li_2Mn0_3-like compound,exhibiting surprising lithium intercalation behavior and capable ofreversibly intercalating a very large amount of lithium ions. XAS andXRD investigations of this material highlights its similarity to the rock-salt monoclinic Li_2Mn0_3. XAS data also shows evidence for occurrenceof Faradaic reduction-oxidation processes in this material with excellentreversibility upon discharge-charge.