The electrochemical coupling of a reactive anode to an air electrode provides a battery with an inexhaustible cathode and, potentially, very high specific energy and energy density. The most important advantage of a metal/air battery is that its active cathode, oxygen, is not carried inside of the battery. Instead, oxygen is extracted from the surrounding ambient environment when it is used. This unique property of metal/air batteries results in a huge advantage in their specific energy (Wh/kg) that is critical for applications that are very sensitive to weight.
Weight of reliable batteries remains an important consideration in the design of aircraft batteries, both in military and civil aviation. Lithium air batteries hold much promise for use in aircraft because of the intrinsic characteristics of air cathode batteries. Since the Li-air battery has the largest specific energy, it is ideally suited for aviation applications.