Investigation of a Li-O2 cell featuring a binder-free cathode via impedance spectroscopy and equivalent circuit model analysis

Many studies of the discharge performance of traditional lithium oxygen (Li-O2) cells with binder also include electrochemical impedance spectroscopy (EIS) data and equivalent circuit models (ECM) to provide additional insight on the electrochemical kinetics driving cell operation. However, no EIS and ECM data have been reported for binder-free Li-O2 cells. In this work, EIS and ECM data are analyzed and first reported for a binder-free Li-O2 cell. The EIS results are consistent with the overall discharge capacity results for a cell that is experiencing increased polarization due to cycling, and the fitted equivalent circuit accurately models the same behavior. Surface morphology is also presented for the cell and exhibits product formation on the cathode that is consistent with increased polarization.