Anodic-peak current density, alloying

Figure 5. 45 shows the two polarization curves predicted for the two alloys under aerated conditions. The solid curve is predicted for the alloy with the higher (H) anodic-peak current density, and the curve defined by the crosses is predicted for the alloy with the lower (L) anodic-... 

The low anodic polarization resistance of Mg and its alloys can be ascribed to the breakdown of the film. At potentials more negative than Ept, the surface is fully covered by a surface film according to the model, and thus the anodic polarization current density does not dramatically increase with increasing potential. The presence of surface film on the surface also accounts for the fact that no active dissolution peak appears on the anodic polarization curve. After the polarization potential becomes more positive than Ept and there are considerable film-free sites or areas, the Mg" " generation and the subsequent further anodic oxidation, disproportionation and hydration of Mg" become significant. Therefore, the anodic current density dramatically increases. 

Since lithium metal is molten at thermal battery discharge temperatures, it is retained on high surface area metals by immersion of the metal matrix in molten lithium to form anodes. Often this structure is contained within a metal cup to prevent leakage during cell operation. Another method is the fabrication of lithium alloy anodes, such as lithium—boron, lithium—aluminium and lithium—silicon, which are solid at battery discharge temperatures and thus offer the possibility of simpler construction. However, the lithium alloys are more difficult to fabricate than the metal matrix anodes and do not achieve this same peak current density. Most of the lithium anode batteries currently use the lithium chloride—potassium chloride electrolyte and an iron disulphide (FeS2) cathode. 

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