The Behavior of Lithium Electrodes in Mixtures of Alkyl Carbonates and Ethers

Cycling efficiency of lithium electrodes in a variety of organic solvent mixtures was measured and correlated with the surface chemistry of lithium in the solutions. The electrolyte systems included LiClO₄ and LiAsF₆ solutions in mixtures of propylene carbonate, ethylene carbonate, tetrahydrofuran (THF), 2-methyl-THF, and dimethoxyethane. Ex situ Fourier transform infrared spectroscopy, scanning electron microscopy, and x-ray microanalysis have been used in order to characterize the surface of the lithium electrodes in the various systems. The influence of active additives (e.g., water, oxygen) was also investigated. It was found that the Li cycling efficiency in all the systems studied depends primarily on a delicate balance of several interacting surface film-forming processes.