Polymer Electrolytes for Al-Air Batteries: Current State and Future Perspectives

Aluminum-air (Al-air) batteries are promising electrochemical storage systems, because of their practicality, low flammability and no risk of explosion, eco-compatibility, and high energy density. However, Al-air batteries realized with liquid electrolytes may present safety concerns, because of leakage, and are unsuitable for miniaturized and portable electronic devices. The transition of the electrolytes for Al-air batteries from aqueous to solid form is an inevitable trend for safety, stability, and possible widespread use. Nevertheless, the manufacturing of new solid electrolytes for Al-air batteries is still a new and largely unexplored field. In fact, the most significant results appeared only in the last decade, with the development of new polymer electrolytes. In this Review, we summarize the most significant findings on polymer electrolytes used in Al-air batteries, particularly emphasizing the cell electrochemical performances and how these relate to the characteristics of the electrolyte.