H. Shigemura et al., Structure and electrochemical properties of LiFexMn2-xO4 (0 <= x <= 0.5) spinel as 5 V electrode material for lithium batteries, J ELCHEM SO, 148(7), 2001, pp. A730-A736
An electroactive spinel solid solution, LiFexMn2-xO4 (0 less than or equal
to x less than or equal to 0.5). was prepared and investigated. X-ray Rietv
eld refinements showed a small amount of transition metal ions in tetrahedr
al 8a sites in Fe-substituted samples. The Fe-57 Mossbauer spectrum of LiFe
0.5Mn1.5O4 at 300 K is composed of two doublets and attributed to trivalent
Fc. In the voltage range 3.0 and 5.3 V vs. Li/Li+. two reversible plateaus
appeared at 4.9 and 3.9 V during discharge. Combined data of X-ray diffrac
tion, Mn K-edge X-ray absorption near-edge structure (XANES), and Fe-57 Mos
sbauer spectroscopy obtained in situ during charge and discharge demonstrat
e that the plateau around 4 V on charging is associated with the oxidation
of Mn3+ to Mn4+ and the plateau around 5 V with the partial oxidation of Fe
3+ to Fe4+. (C) 2001 The Electrochemical Society.