Mössbauer studies of structural properties and electrochemical characteristics of LiFePO 4

Abstract

The valency state and local coordination of Fe ions of four industrial samples and a sample of cathodic materials for recharcheable lithium ion batteries obtained using an original technology of St. Petersburg State Technological Institute (Technological University) were studied using the Mössbauer effect on the 57Fe isotope. It was found that the main valency state for more than 90% of iron ions was Fe 2+. The values of isomer shift δ = 0.96-0.98 mm/s and quadrupole splitting σ = 2.88-2.93 mm/s for Fe 2+ ions coincide with the values for compounds with the structure of olivine LiFePO 4 and occupy positions in highly distorted FeO 6 octahedrons. Fe 3+ ions are in octahedral and/or tetrahedral local positions. © 2012 Pleiades Publishing, Ltd.