AC-Impedance Investigations of Li-Ion Batteries with Wide Temperature Performance

Abstract

Solid electrolyte interphase (SEI) of lithium-ion batteries in three electrode pouch cells was studied by using electrochemical impedance spectroscopy (EIS). Two kinds of electrolytes were used for the comparison purpose. Electrochemical impedance of individual electrodes and the full cell was measured in various state of aging, charge and temperature conditions. The equivalent circuit was identified through distribution of relaxation times (DRT), and then used to fit the impedance data. The results show that majority of the full cell impedance at -20℃ arises from anode SEI.