Metal air batteries have been attracting many works in the
electrochemistry research and development communities for the
last 50 years. They have much higher specific energies than most
currently available primary and rechargeable batteries. Their
attractiveness lies in their source of oxidizing agent: for the
cathodic reaction the oxygen comes from outside environment,
mostly from air or O2, rather than from inside the battery. These
aspects lead to high densities of specific energy (Wh kg1), in
theory much higher than those of Li-ion batteries [1]. Many metals
can be used as negative electrode with energy densities that vary
with the metals nature due to the number of electrons exchanged,
the metal molecular weight and the electrode potential. The largest
theoretical energy densities (Table 1) would be obtained for
lithium-based batteries, silicon, aluminium, magnesium and would
be much higher than 1700 Wh kg1 [2]. However, these values are
based on the mass of metal alone. All metaleair cells gain mass (O2
or OH) as they discharge. Moreover, other parameters as the
weights of electrolyte and air electrode, as well as the potential
diminution due to parasitical reaction are not taking account. For
example, specific energies are estimated to 900 Wh kg1 for Lieair
battery [3] and 400 Wh kg1 for primary aluminium air battery [4]