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

Metal–air batteries have a theoretical energy density that is much higher than that of lithium-ion batteries and are frequently advocated as a solution toward next-generation electrochemical energy storage for applications including electric vehicles or grid energy storage. However, they have not fulfilled their full potential because of challenges associated with the metal anode, air cathode, and electrolyte. These challenges will 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 nonaqueous (e.g., Li–air) systems. An overview of the general technical issues confronting their development is presented, and our perspective on possible solutions is offered.