The S3E methodology effectively eliminates the intrinsic non-stationarity of direct current measurements, as is discussed in detail in our previous work . Briefly, the S3E-CP method consists of applying a series of short galvanostatic pulses across a wide range of current densities, while cycling the cell back to the same initial condition between each pulse. To approximate steady-state conditions, the voltage versus capacity data for each current pulse is extrapolated to a capacity of zero, yielding a dataset of voltage versus current. The overpotential is calculated by a subtraction of the IR drop, and the BV kinetic parameters can be fitted from the overpotential versus current data. S3E-CP measurements provide only the apparent electrode-level kinetic response, and unlike EIS, cannot directly deconvolute the contributions of multiple resistive processes within the electrode. Specifically, when Rct ≈ Rp, a non-uniform current distribution can occur within the porous electrode at high current densities, which is generally expected to preclude accurate measurement of the BV kinetic parameters . Accurate S3E-CP measurements of α and I0 can be obtained in the limiting case of Rct ≫ Rp, where the current distribution is uniform at high current densities; this condition can often be achieved with thin electrodes. However, there is also a limiting case in which Rct ≪ Rp (i.e., Rct is immeasurably small and cannot be detected by EIS). In this case, the current distribution becomes semi-infinite at high current densities, resulting in a "double Tafel slope" behavior: this allows for an indirect measurement of the apparent α value of the AM .