Rechargeable Graphite Fluoride Electrodes Realized by Fluoride Anion Insertion and Deinsertion

This study found for the first time that F- anions can be electrochemically inserted or deinserted into or from carbon based materials, respectively, using a combination of graphite fluoride (GF) and a Li-based organic electrolyte with a suitably high potential (> 5.0 V vs Li+/Li). The GF materials used in this study produced amorphous carbon and LiF after the first discharge, with a discharge capacity of 600 mAh g(-1) that was almost in line with the theoretical value (about 630 mAh g(-1)). As determined by subsequent electrochemical measurements, a reversible charge or discharge capacity of -200 mAh g(-1) in addition to a Coulombic efficiency of -86% and a capacity retention of -85% after 30 cycles were observed within a potential range of 1.5-5.3 V. Various analyses clearly demonstrate that the electrochemical properties resulted from the reversible insertion and deinsertion of F- anions into and from amorphous carbon formed in the GF cathode, respectively, which was triggered by the formation of LiF, the source of the F- anions.