Electrochemical and Computational Insights into Lithium Nucleation on Single-Crystal Copper for Anode-Free Li-Metal Batteries

Anode-free lithium (Li) metal batteries promise high energy density due to the absence of graphite on the anode side, whereby Li is directly electroplated onto the current collector during charging. Copper (Cu) foil is commonly used as a current collector; however, dendritic growth, which can cause catastrophic failure, is often observed. Optimizing nucleation is one of the proposed strategies for obtaining smooth, dendrite-free Li deposits. This work investigates nucleation of Li onto a Cu(111) single crystal by electrochemical impedance spectroscopy (EIS) and density functional theory (DFT) calculations. EIS allows for the monitoring of kinetic deposition parameters (kapp(t,E)) as a function of potential and time, offering a more profound insight into early stage deposition mechanisms. It is shown that kapp(t,E) decreases with increasing deposition potential, while over the course of deposition a decrease can be observed during the initial stages of deposition. Furthermore, DFT calculations show a decreasing trend in adsorption strength with Li coverage, providing additional atomistic insights into the decreasing time-dependent behavior of the kinetic parameters.