Without the relaxation step, dEOC/dtI, can be 1) obtained from existing OCP data of the electrode material or 2) approximated by the slope of iR-corrected pseudo-OCP. The iR-drop and pseudo-OCP, referring to the measured potential under low constant current, are readily available in the ICI analysis. From two neighboring current interruptions, the change in OCP can be approximated by the change in E(∆t=0), which is the potential right before the current pause subtracting the iR-drop, as shown in Equation 17. The validity of using ∆[E(∆t=0)]/∆tI as dEOC/dtI will be examined in Section 3.