Electrochemical studies of three types of CF x (F – fiber based, C – petroleum coke based, G – graphite based) have demonstrated different electrochemical performances in previous work, with fiber based CF x delivering superior performance over those based on petroleum coke and graphite. 13C and 19F MAS (magic angle spinning) NMR techniques are employed to identify the atomic/molecular structural factors that might account for differences in electrochemical performance among the different types of CF x . Small quantitative variations of covalent CF and LiF are noted as a function of discharge and sp3 bonded carbons are detected in discharged F type of CF x .