Operando investigations of the interfacial electrochemical kinetics of metallic lithium anodes via temperature-dependent electrochemical impedance spectroscopy

One of the major hurdles in the utilization of metallic lithium anodes is understanding the Li+transfer kinetics through the solid electrolyte interface (SEI) in addition to Li oxidation. Electrochemical impedance spectroscopy (EIS) combined with temperature variation provides deeper comprehension and reveals kinetic parameters of individual processes separately. In this study, we report temperature-dependent EIS analysis of metallic Li anodes to shed light on the kinetics of anodic/interfacial processes at different states of charge and wide temperature ranges (-25 to 75 °C), utilizing lithium thionyl chloride (Li/SOCl2) and lithium manganese dioxide (Li/MnO2) primary batteries as model systems. We found in both batteries that the impedance of the SEI processes is highly temperature-dependent with non-Arrhenius behavior at temperatures greater than 35 °C. Conversely, the kinetics of the anodic process showed small temperature dependence that is explained by the Arrhenius equation throughout the temperature range studied. The results provide a deeper understanding of the underlying processes separately in metallic Li anodes under operando and real-time conditions. © 2022 American Chemical Society. All rights reserved.