Y. Eineli et D. Aurbach, THE CORRELATION BETWEEN THE CYCLING EFFICIENCY, SURFACE-CHEMISTRY ANDMORPHOLOGY OF LI ELECTRODES IN ELECTROLYTE-SOLUTIONS BASED ON METHYL FORMATE, Journal of power sources, 54(2), 1995, pp. 281-288
The correlation between Li-cycling efficiency, morphology and surface
chemistry in methyl formate (MF) solutions have been investigated. The
salt included LiAsF6, LiClO4, LiBF4, and their mixtures. Propylene et
hylene, dimethyl and diethyl carbonates, tetrahydrofuran and 1,3-dioxo
lane were used as co-solvents. The impact of CO2 as an additive was al
so explored. Ex situ surface sensitive Fourier-transform infrared spec
troscopy (FT-IR) and scanning electron microscopy were used in conjunc
tion with standard electrochemical techniques. Li-cycling efficiency w
as measured in half-cell testing of electrodes prepared by Li depositi
on on copper. The Li-cycling efficiency in all MF solutions is poor du
e to the instability of the surface films formed on Li in this highly
polar solvent. The use of CO2 enabled high Li-cycling efficiency to be
obtained due to an efficient passivation of Li2CO3 formed on Li when
CO2 was present. The performance of Li electrodes in these systems cou
ld be further optimized by the use of the appropriate co-solvents. The
factors which determine the anode utility in these systems are discus
sed.