In this experiment, an aluminum-air battery was constructed, based on common household supplies.
1) (-) electrode (anode) material:
Thin aluminum foil was used as the anode material.
The thin interlayer between the electrodes is called a membrane. In this experiment, a piece of paper towel served as the membrane. The membrane separates the reducer (Al) from the oxidizer, but allows free passage for hydroxide (OH-) ions.
3) (+) electrode (cathode) material:
The cathode was made of porous graphite powder capable of absorbing molecules of oxygen, glued onto an iron wire sponge (commonly used for scrubbing kitchenware).
First, the components of the battery were assembled dry, followed by their immersion in electrolyte solution. A solution containing sodium hydroxide (NaOH) and sodium chloride (NaCl) was used as the electrolyte.
1) Anode reaction (on - electrode):
The oxidation of aluminum and binding with hydroxide ions (OH-):
Al(s) + 3OH-(aq) → Al(OH)3(s) + 3e-
2) Cathode reaction (on + electrode):
Reduction of molecular oxygen and water molecules bind to form OH--ions:
O2(g) + 2H2O(l) + 4e- → 4OH-(aq)
Total: 4Al(s) + 3O2(g) + 6H2O(l) → 4Al(OH)3(s)
The obtained voltage was about 2V.
Aluminum-air batteries have allegedly found military application as power sources for the electric motors of torpedoes.