A systematic overview of power electronics interfaced electrochemical impedance spectroscopy for energy storage systems

The Effect of Oxygen Vacancy Defects on the Structure and Electrochemical Behaviors of LiMn0.65Fe0.35PO4 Cathode

“…There is no doubt that the EIS curves of all samples are composed of a semicircle as well as an inclined straight line, with the region corresponding to the semicircle being the high and mediumfrequency region and the region corresponding to the straight line being the low-frequency region. 32,33 The intersection of the semicircle with the horizontal coordinate represents the ohmic resistance (R s ), which is mainly determined by the electrolyte and the inherent resistance of the shell used, as the four LiMn 0.65 Fe 0.35 PO 4 cells were prepared by the same method, so the ohmic resistance of the four cells is close to each other. The semicircle corresponds to the charge transfer impedance (R ct ), which is the impedance caused by the diffusion of Li + at the contact interface between the electrolyte and the LiMn 0.65 Fe 0.35 PO 4 material.…”

“…The sloping straight line represents the Warburg impedance (W1), whose magnitude is determined by the diffusion rate of Li + in the LiMn 0.65 Fe 0.35 PO 4 material.Using Z/view software to fit the EIS data, a plot of Z' vs ω −1/2 can be obtained as shown in Fig.6b, whose slope is the Warburg coefficient (σ), and the Li + diffusion coefficient (D Li ) can be calculated from the Eqs. 1 and 2 33.…”

“…Figure6ashows the EIS test profiles of the four LiMn 0.65 Fe 0.35PO 4 samples, and the inset shows the equivalent circuit used in fitting the EIS data. There is no doubt that the EIS curves of all samples are composed of a semicircle as well as an inclined straight line, with the region corresponding to the semicircle being the high and mediumfrequency region and the region corresponding to the straight line being the low-frequency region 32,33. The intersection of the semicircle with the horizontal coordinate represents the ohmic resistance (R s ), which is mainly determined by the electrolyte and the inherent resistance of the shell used, as the four LiMn 0.65 Fe 0.35 PO 4 cells were prepared by the same method, so the ohmic resistance of the four cells is close to each other.…”