Electrochemical deposition of very smooth lithium using nonaqueous electrolytes containing HF

X-ray photoelectron spectroscopy and scanning electron microscopy methods were used for analysis of the surface layers of lithium deposited at various current densities from propylene carbonate containing 1.0 mi dm(-3) LiClO4 and various amounts of HF, to investigate the effect of HF in electrolytes on the surface reaction of lithium during electrochemical deposition. Our analyses indicate that the surface state of lithium and the morphology of lithium deposits are influenced by both the concentration of HF and the electrodeposition current. The first parameter for the electrodeposition of lithium is related to the chemical reaction rate of the lithium surface with HF and second to the electrodeposition rate of lithium. These results suggest that surface modification is effective in suppressing lithium dendrite formation when the chemical reaction rate with HF is greater than the electrochemical deposition rate of lithium.