Lithium-air batteries: Challenges coexist with opportunities

Lithium-air batteries have caught worldwide attention due to their extremely high theoretical energy density and are regarded as powerful competitors to replace traditional lithium ion batteries. However, it is rather critical how to maximize the capacity while keeping good cycling stability, which has impeded practical applications of Li-air batteries for decades. Although admirable achievements have been made in recent years, there are still many unsolved issues for developing practical Li-air batteries. In this review, the challenges are pointed out and the recent progress in cathodes, anodes, and electrolytes is also summarized for Li-air batteries, as well as the relationship between each part for better electrochemical performances. Furthermore, some inspiring results on constructing advanced Li-air batteries are discussed particularly. Finally, opportunities and perspectives are also provided.