Lithium iron phosphate (ordered olivine-type structure) is emerging as the most promising material to replace lithiated transition metal oxide as cathode material for secondary lithium-ion batteries [1–4]. LiFePO
is inexpensive, non-toxic, environmentally benign, and has a theoretical specific capacity of 170 mA h
. Padhi et al. [5] showed that lithium can be extracted from LiFePO
and inserted into FePO4
along a flat potential at 3.5 V vs. Li. During the lithium