The batteries with air cathode have the highest energy density have among other battery types. The superiority of the
[Metal anode] / [electrolyte]/[oxygen (gas) cathode]
design is based on the fact that there is no need to store oxygen (the cathode active material) inside the cell because it can be delivered from the atmosphere.
Up to now, metal-oxygen batteries are aqueous systems par excellence; the most common system is Zn-air cell. The studies on this cell have revealed that the kinetics of the whole battery is controlled by the cathode reaction.
Nowadays, (Li, Si, Al, Mg)-air cell chemistries emerges; the advantage of these chemistries is a very high specific capacity of these metals, which is substantially higher than the specific capacity of zinc:
- 3842 mAh/g for Li,
- 3816 mAh/g for Si,
- 2965 mAh/g for Al,
- 2204 mAh/g for Mg,
- Only 815 mAh/g for Zn.
