In Situ Optical and Electrochemical Investigations of Lithium Depositions as a Function of Current Densities

Abstract

The electrodeposition behavior of lithium metal as a function of the current density at room temperature was investigated in a symmetrical face‑to‑face in‑situ optical cell. After a defined initial contact time between electrode and electrolyte, various current densities in the range of 0.05 mA cm−2 to 10 mA cm−2 were tested. Constant current phases, electrochemical impedance spectroscopy measurements and in situ images of the working electrode were recorded and results were compared. Two regimes of lithium deposition with different optical and electrochemical characteristics were identified as a function of current density. The first regime, at low current densities (0.05 mA cm−2–0.5 mA cm−2), showed none to tiny lithium depositions with sporadic large lithium structures at the higher end of this range. The second regime, at high current densities (2 mA cm−2–10 mA cm−2), showed many smaller, deposited lithium structures. The experimental results are discussed in the context of the formation and presence of metal-electrolyte interfaces presumably by chemical reactions between lithium and electrolyte , current density and their interactions with each other. The correlation of fundamental parameters of lithium metal deposition with current density must be taken into account for the development of lithium metal-based energy storage devices.