Lithium insertion in lithium iron molybdate

We report here, for the first time, facile and reversible insertion/extraction of lithium in LiFe(MoO4)(2). A biphasic reaction is observed in the compositional range 0<0.9 in Li1+xFe(MoO4)(2) with a remarkably flat plateau at an average voltage of 2.68 V due to the redox couple Fe3+/Fe2+. An irreversible structural change was associated with lithium insertion. The plateau behavior is reversible with negligible hysteresis (Delta dQ/dV = 0.05 V) and 100% Faradaic efficiency. A reversible capacity of 63 mAh/g is obtained in the voltage window 3.0-2.5 V. When reduction of Mo6+ is also accessed by cycling in the voltage window 3.0-1.0 V. a reversible capacity of similar to 180 mAh/g was obtained at the end of 20 cycles at C/5 rate. (C) 2012 Elsevier B.V. All rights reserved.