Decoupling of the Impedance of Solid-Electrolyte Interface and Plated Lithium: Implications for Anode-Free Lithium Metal Battery Technology

The understanding of the impedance response during the cycling process of the “anode-free” lithium metal batteries is ambiguous in the literature. Herein, we report on a combined electrochemical quartz crystal microbalance and electrochemical impedance spectroscopy study to decouple the various contributions of the impedance response of an anode-free battery. This decoupling is achieved by a comparison of the evolution of electrochemical impedance spectroscopy spectra in two- and three-electrode cells during the Li plating–stripping processes. The observed high- and medium-frequency loops of the impedance spectra can be unambiguously assigned to the charge transfer in the solid-electrolyte interface and the plated lithium layers, respectively.