A review of the Al-gas batteries and perspectives for a “Real” Al-air battery

Aluminum-gas battery is a special kind of fuel cell that converts chemical energy directly into electrical energy, possessing the advantages of high specific energy density, higher safety, and low cost. Different types of Al-gas batteries are classified by cathode active gases, such as Al–O2, Al–N2, and Al–CO2 batteries, reducing a single gas respectively. Up to date Al-gas batteries using multi-component as cathode active gases are rarely reported, even the intensively researched Al-air batteries actually only reduce O2 from the air. Coincidentally, N2 and CO2 are also the main components in the air, it is an attractive work to discuss and research several gases together as cathode active gas. This review tries to illustrate the electrode structure, catalytic principle, and electrolyte composition of different types of Al-gas batteries, explore the differences and connections between different active gases on diffusion, reduction, and transition, prospecting to construct a real aluminum-air battery in the future.