Development and manufacture of air cathodes and aluminum-based anode alloys and electrodes
The efficiency of operation of air-aluminum fuel cells is defined by the activity of air cathode and aluminum-based anode.
Air cathode is a complex porous hydrophilic-hydrophobic system which provides for the stability of the three-phase interface and for the delivery of oxygen to this interface and for the removal of resultant products. The cathode consists of two layers, namely, active and gas-diffusion ones.
The active layer, in which the three-phase interface is established and the reaction of reduction of air oxygen occurs, consists of activated carbon, acetylene black, and fluoroplastic. Activated carbon serves the function of catalyst. Acetylene black is added as electrically conducting addition. Fluoroplastic serves the function of water repellent.
The gas-diffusion layer provides for the delivery of air oxygen to the three-phase interface of the active layer and prevents the electrode from soaking.
The electrode activity is defined both by the materials employed and by the methods of their manufacture. Methods of manufacturing two-layer cathodes have been developed at INEP, and their small-scale production has been launched for use in AA ECG under development. Investigations of cathodes are under way, which are associated with the transition to new types of activated carbon, acetylene black, and fluoroplastic. Permanent control is exercised over the employed raw materials and intermediate products.
The anode is an alloy of highly pure aluminum and microadditives. Various metals are employed as microalloying additives. They must, on the one hand, activate the process of anode dissolution and, on the other hand, inhibit corrosion. Most extensively employed are metals such as bismuth, gallium, indium, magnesium, tin, lead, and zinc. The alloy efficiency is defined both by the nature of additive and by the ratio of various microadditives and the uniformity of their distribution.
Therefore, the investigations are directed towards studying the impact made by various alloying additives, by their ratio in the alloy, and by the uniformity of their distribution on the electrochemical and corrosion activity. Methods are under development for producing such alloys, for their rolling, and for manufacturing anodes for use in AA ECG.
