Surface film covered

The surface films covering the active metals are formed by a gradually decreasing driving force. When the fresh, active metal is exposed either to reactive gases or to solution species, its reactivity is maximal, and, thus, reduction of atmospheric or solutions components takes place under highly nonselective conditions. Any bare metal surface is readily... 

Figure 4 A schematic description of the influence of water in solutions on the structure of surface films covering active metal electrodes.

CONSIDERATION IN SURFACE FILMS COVERING ACTIVE METAL ELECTRODES IN SOLUTIONS... 

In conclusion we emphasize that the final chemical composition of the surface films covering Li electrodes in solutions is the result of a delicate balance between several competing reduction processes of solvent, salt anion, and contaminants. In this section we emphasize the role of salt reduction processes. However, each solution has to be studied separately since the above balance is determined by factors such as salt concentration, the nature of the solvent, contamination level, etc., all of which differ from system to system. Table 4 presents element analysis by XPS of surface films formed on freshly prepared Li electrodes in several solutions. It demonstrates how the impact of salt reduction on the Li surface chemistry depends on the solution composition and the storage time. (The atomic percentage of fluorine on the surface is a good measure for the impact of the salt.)... 

In contrast to the case of lithium, where extensive efforts have been devoted to the study of interfacial phenomena, surface film composition, etc., very little is yet known about the composition and structure of the surface films covering magnesium electrodes in nonaqueous media. In addition, the mechanisms of Mg dissolution and plating in the Grignard solutions are unclear. 

Much information about lithium deposition/dissolution on inert electrodes has been obtained over the past twenty years. Thorough smdies of the chemical composition of surface films of lithium deposited on a nickel substrate in y-butyrolactone (y-BL) and tetrahydrofurane electrolytes, containing various salts, such as LiClO., LiAsF, LiBF and LiPF were carried out by Kanamura et al. With the use of XPS it was found, that the outer and inner layers of the surface film covering lithium in LiClO y-BL involve LiOH or possibly some LqCO,... 

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