On the basic electrochemical behavior of active metal and Li-C anodes. New insights

In this paper we review some new results related to three types of active electrodes: lithium, lithiated graphite and magnesium. We comment on surface studies of active electrodes by XPS and FTIR spectroscopy, and show that only the combination of these two methods may provide complementary specific information with which the reliable analysis of surface films on active electrodes can be completed. We demonstrate the effect of current density on the surface chemistry, morphology and performance of Li electrodes, e.g. only at high discharge currents are the pristine surface films on Li electrodes replaced by species originating from the reduction of solution compounds, this having a pronounced effect on Li surface morphology. We also provide evidence for LiH formation on Li in ethereal wet solutions. We describe the mechanism of deactivation of a Li-graphite electrode which occurs at potentials as high as 1V vs. Li/Li+. Finally, we describe some fundamental phenomena which relate to Mg electrodes. We review the results of EQCM measurements that show reversible Mg deposition at an efficiency close to 100% in ethereal solutions which occur in a surface film free condition, but involve reversible adsorption-desorption processes of solution species.