Oxide cathodes oxygen loss from

Figure 4. Schematic illustration of corrosion induced paint adhesion loss. In the initial stage (A), iron is oxidized and oxygen reduced at a site of electrolyte penetration as corrosion proceeds (B and C), a rust deposit forms and the anodic and cathodic reaction sites become separated. Cathodically produced hydroxide progressively disrupts paint adhesion. Reproduced from Ref. 25, copyright 1980, American Chemical Society.

There are different kinds of DAFC operation conditions depending of the way the fuel and the oxidant (oxygen/air) are fed into the cell. In complete active fuel cells the liquid fuel (neat alcohol or aqueous solution) is pumped and gas is compressed, using auxiliary pumps and blowers, in order to improve mass transport and reduce concentration polarization losses in the system. On the other hand, in complete passive DAFC the alcohol reaches the anode catalyst layer by natural convection and the cathode breathes oxygen directly from the air. A number of intermediate options have been also studied and tested. 

Aluminum is produced according to the Hall-Heroult process [42-44]. At the cathode, AlxFy species are reduced and lead to liquid aluminum. As the electrolysis proceeds, the metal from the aluminum oxide precipitates at the bottom of the cell. At the anode, oxygen evolution takes place producing carbon dioxide/monoxide and hence resulting in current and performance losses [42-44]. 

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