| A study of charge cycling at the lithium metal/Poly[bis(2,3-di-(2-methoxyethoxy)propoxy)phosphazene] (SPE)/Intercalation Cathode (IC) battery system is reported. Irreversible processes occurring at the IC have been characterized by using high-sensitivity dilatometry and Electrochemical Impedance Spectroscopy (EIS) as a function of cycle number. It was found that the cathode processing method plays an important role in the performance of such cathodes. The volume of the casted cathodes increased monotonically with the cycle number and reached a steady state. These cathodes see a sudden increase in impedance after a certain number of cycles. For the pressed cathodes, the impedance was found to remain relatively stable over the entire cycling time and their volume also remains stable. From the impedance data, it can be seen that the non-ohmic part of the measured Li/SPE/IC cell impedance is dominated by the SPE impedance, while the IC impedance determines the ohmic part of the total cell impedance. The composition of the IC was also studied and results show that, once above the critical concentration threshold, carbon black concentration has no notable effect on the cell performance., nor does the crystal structures of the cathode active material, MnO2 . The interface between SPE and IC was found to be stable over the entire cycling period. Three simple percolation models were developed to account for the IC impedance behavior. |
