Metal–Air Batteries: Will They Be the Future Electrochemical Energy Storage Device of Choice?

Metal-air batteries have much higher theoretical energy density than lithium-ion batteries, and are frequently advocated as the solution toward next-generation electrochemical energy storage for applications including electric vehicles or grid energy storage. Yet they have not fulfilled their full potentials as limited by challenges associated with the metal anode, air cathode and electrolyte. These challenges would have to be properly resolved before metal-air batteries can become a practical reality and be deployed on a large scale. Here we survey the current status and latest advances in metal-air battery research for both aqueous (e.g. Zn-air) and non-aqueous (e.g. Li-air) systems. The general technical issues confronting their developments are overviewed, and our perspective on possible solutions is offered.