Accurate measurements of Rct require quantitatively accounting for the ohmic resistance of the cell, particularly the pore resistance (Rp) of the electrodes. Rp can be measured with PEIS of symmetric cells under blocking conditions, which use the same electrolyte as for intercalating conditions, but are assembled with pristine electrodes . This approach requires careful control of the electrode coating and cell building process to ensure that the coat weights of the electrodes are nearly identical (e.g., < 2% different) between separate cells. The solution resistance (Rs) for both cells is determined by a linear interpolation of the high-frequency (HF) intercept of the impedance spectra. The low-frequency (LF) intercept under blocking conditions is calculated by a linear extrapolation of LF impedance data to ZIm = 0 (Fig. ). The difference between the HF and LF intercepts is equal to one third of the pore resistance (Rp/3) . The total ohmic resistance (RΩ) under intercalating conditions is the sum of the solution resistance and pore resistance.