Use of Electrochemical Impedance Spectroscopy and In-situ XRD for Characterization of Cathodes for Li-Sulfur Batteries

Kurzfassung

Li-S batteries undergo significant structural and morphological changes during cycling. As a result, the specific capacity of the battery decreases considerably, especially in the first cycles. In order to optimize the performance of the cell, it is highly important to understand the degradation processes of sulfur cathode under operating conditions. In the present work, x-ray diffraction (XRD) and electrical impedance spectroscopy (EIS) were measured during cycling. The formation of crystalline products was monitored in-situ and semi-quantitatively determined by XRD- analysis. Impedance measurements were performed during the first cycle at a frequency range of 1 MHz to 60 mHz. Impedance spectra were investigated at several states of charge distinguishing the impedance contributions of the different physical/chemical phenomena occurring in the battery. Furthermore, the aging during cycling was studied until fifteen cycles. Our results provide new insights into the discharging and charging processes of Li-Sulfur batteries by means of EIS and XRD characterization.