Advances in flexible lithium metal batteries

Flexible energy storage devices are becoming indispensable new elements of wearable electronics to improve our living qualities. As the main energy storage devices, lithium-ion batteries (LIBs) are gradually approaching their theoretical limit in terms of energy density. In recent years, lithium metal batteries (LMBs) with metallic Li as the anode are revived due to the extremely high energy density, and are considered to be one of the ideal alternatives for the next generation of flexible power supply. In this review, key technologies and scientific problems to be overcome for flexible LMBs are discussed. Then, the recent advances in flexible LMBs, including the design of flexible Li metal anodes, electrolytes, cathodes and interlayers, are summarized. In addition, we have summed up the research progress of flexible device configurations, and emphasized the importance of flexibility evaluation and functionality integration to ensure the wearing safety in complex environment. Finally, the challenges and future development of flexible LMBs are summarized and prospected.