Impedance measurements of low temperature mesophase carbon fibers during lithium insertion/extraction

The cause of the improvement was examined mainly with impedance spectroscopy analysis (EIS). EIS spectra revealed that both the film resistance and the charge-transfer resistance were decreased remarkably by these surface modifications. Among the three modification procedures, MOT revealed the best improving effect. By comparing the EIS data with the results obtained from the double layer capacity measurement, we concluded that the major cause of the increase in the reaction rate is the activation of the reaction site.