Mini review: Recent advances on flexible rechargeable Li-air batteries

With the increasing demand on wearable electronic devices, flexible metal-air batteries, including Zn-air, Li-air, Mg-air, and Al-air batteries, have received more and more attention in recent years. Among them, the Li-Air battery has become more promising as a result of its ultrahigh theoretical energy densities of about 3500 Wh kg^-1. Numerous efforts have been devoted to structure design and study on mechanisms for a flexible Li-air battery (FLAB); however, there still remain numerous problems that hinder its commercial application, including unstable electrode reactions, excessive cost, deficiency flexibility for particular use, etc. Herein, we present a brief introduction on the evaluation of FLAB and then introduce the structure design of different types of FLAB. Finally, we summarize the bottleneck problems of FLAB and outlook the prospect of the research and development of FLAB in the future.