Two rechargeable polymorphs of LiFeO2 have been synthesized at low temperatures of less than 250 °C via a novel H+/Li+ ionic-exchange reaction in an alcoholic solution using stoichiometric amounts of lithium alkoxide and iron oxyhydroxide as the starting materials. The reaction, which proceeded in a topotactic manner, resulted in new polymorphs in the LiFeO2 family with similar crystal structures to the parent materials. Two types of LiFeO2, the corrugated layer and goethite type, were rechargeable in lithium cells with a cycling capacity of 0.2-0.4 Li/LiFeO2 in the 1.5-4.5 V range, unlike the other six non-rechargeable polymorphs reported so far. A preliminary X-ray diffraction study on structural changes in the cathode during cycling showed a minimal lattice parameter change for corrugated layer LiFeO2 and a noticeable a-lattice shrinkage/expansion of about 1% for goethite-type LiFeO2.
All Science Journal Classification (ASJC) codes