ABSTRACT
The presence of a residual fluoride in the GIC as confirmed by 19F and 13C NMR analysis [31] may induce an increased ionic character of the carbon layers, which bear a partial positive charge to balance the negative one of the interca lated anions (AsFg, PFg, . . .) . The electrode reaction may imply the formation of an intermediate complex involving the intercalated fluoride as follows:
+ (z — e)LiF + z«(solv)
Equation (11) describes the irreversible decomposition of the electrode as is the case in HT-CF. Note that the electrode capacity increases with the fluorine content in the CFx(AFy+1)e compounds to reach practical values as high at 667 mAh/g for iodine-based GICs [11]. The results obtained with semicovalent car bon fluorides are similar to those reported with HT-CF and C2F compounds: C2F yields higher discharge voltage and lower specific capacity compared to CF [17].
