Impedance investigation of the high temperature performance of the solid-electrolyte-interface of a wide temperature electrolyte.

The high temperature cycling performance of a wide temperature electrolyte and the solid electrolyte interphase (SEI) along the cycling were investigated using a three-electrode pouch cell. The electrolyte developed in our lab demonstrated outstanding low temperature performance. The electrolyte was found to have a good and stable cycling performance at a high temperature in comparison with a state-of-the-art baseline electrolyte. Electrochemical impedance spectroscopy (EIS) was conducted on the anode, the cathode and the full cell independently with a reference embedded pouch cell. The distribution of relaxation times (DRT) transformation was calculated from the EIS spectrum. An equivalent circuit model was used to fit the anode EIS data and the electrochemical process on the anode was revealed. We concluded that a denser SEI layer was built on the anode of the improved electrolyte.