Phase Diagram of Li[sub x](Mn[sub y]Fe[sub 1−y])PO[sub 4] (0≤x, y≤1)

The room temperature ( x , y ) two-dimensional phase diagram of the olivine-type solid-solution, orthorhombic, is determined. The x -dependent changes in the unit cell dimensions at various fixed Mn contents y are analyzed in detail. The manganese substitution for iron in the octahedral 4c sites induces 1, the two-phase redox region with a potential of 4.1 V vs. 2, a partial conversion of the form of the redox reaction (3.4 V vs. from two-phase to single-phase; and 3, phase instability at the composition region close to the point ( x , y ) = (0, 1) caused by the Jahn-Teller effect of The conversion, 2, is complete at around The phase instability, 3, makes the Mn-rich phase unsuitable for battery applications. The local lattice deformation around is severe enough to induce significant selective damping in the extended X-ray absorption fine structure for © 2001 The Electrochemical Society. All rights reserved.