The effect of desiccants on the cycling efficiency of the lithium electrode in propylene carbonate-based electrolytes

Cycling efficiencies of the Li electrode ,in propylene carbonate (PC) 1 M in either LiClO₄ or LiAsF₆ were assessed as a function of electrolyte purification procedure. The use of neutral alumina and galvanostatic pre-electrolysis resulted in the highest efficiency values to date. While cyclic voltammograms at Pt or vitreous C were insensitive to electrolyte impurities, voltammograms on Ni about the Li potential were very informative. Thus, the repeated deposition and subsequent removal of thin (2 mC/cm²) Li plates revealed enhanced nucleation but diminished rate of growth of the nuclei as cycling progresses. A model of Li encapsulation is proposed to account for the eventual failure of the Li electrode.