V) plots provides qualitative evidence of non-linearity, while differences in current between the anodic and cathodic direction indicate asymmetry . From LASV measurements of LCO symmetric cells, the kinetics appear to be highly non-linear, but almost perfectly symmetric (Fig. ). This non-linearity is also visible in the voltage versus time data from LA-GEIS measurements (Fig. ). A decrease in resistance with increasing excitation amplitude is viewed as a telltale sign of non-linear behavior during EIS measurements . Indeed, the decrease in interfacial impedance with increasing excitation amplitude for LA-GEIS measurements is clear evidence of non-linear kinetics (Fig. ). In the literature, it has sometimes been stated that the EIS data are "corrupted" by this non-linearity, rendering the data invalid for methods of data analysis which assume linearity, such as equivalent circuit analysis . On the contrary, this decrease in interfacial resistance is not an artifact or distortion of the impedance data; it is literally the physical manifestation of the non-linear current versus overpotential relationship. In fact, this decrease in interfacial resistance with increasing current is exactly the non-linearity which must be experimentally measured to fit the electrochemical data to the BV equation.