A High-Capacity Cathode for Lithium Batteries Consisting of Porous Microspheres of Highly Amorphized Iron Fluoride Densified from Its Open Parent Phase

An FeF3 cathode with very high reversible capacity, exceeding 200 mAh g-1, is achieved by amorphizing of FeF3. The amorphization is achieved by densifying the open structure phase along with the removal of channel H2O at 0 degrees C in BmimBF4. This process is accompanied by a voltage increase of 200 mV. The generation of a hierarchical electron/ion wiring network, enabled by the interaction of ionic liquid with carbon nanotube and FeF3 surfaces, significantly improves the reversibility.