Ye Zhang is currently an associate professor at the College of Engineering and Applied Sciences at the Nanjing University. She received her Ph.D. degree in Macromolecular Chemistry and Physics from the Fudan University in 2018 and then joined the Harvard Medical School as a postdoctoral research fellow. Her research focuses on the development of soft electronics including batteries, sensors, and bioelectronic devices.Lie Wang is currently a postdoctoral scholar at the Nanjing University. He received his PhD in Macromolecular Chemistry and Physics from the Fudan University in 2020. His research focuses on the development of flexible energy and electronic devices and their wearable applications.Yang Zhao is currently an associate professor in Northwestern Polytechnical University. He received his PhD degree in Macromolecular Chemistry and Physics from Fudan University in 2020. His research interests are focused on the development of flexible and multifunctional energy storage devices with high safety.Huisheng Peng is currently a university professor at Fudan University. His interest focuses on polymer fiber electronics. He has published over 300 papers and four books. Professor Peng has also obtained 79 licensed patents with 36 royally transferred to the industry.

• 1 Introduction to flexible batteries 2 Flexible thin-film lithium-ion batteries 3 Fiber lithium-ion batteries 4 Flexible aqueous lithium-ion batteries 5 Flexible aqueous sodium-ion batteries 6 Flexible aqueous zinc-ion batteries 7 Flexible lithium-air batteries 8 Flexible aluminum-air batteries 9 Stretchable Batteries 10 Integration of flexible batteries 11 Summary and Outlook

Ye Zhang is currently an associate professor at the College of Engineering and Applied Sciences at the Nanjing University. She received her Ph.D. degree in Macromolecular Chemistry and Physics from the Fudan University in 2018 and then joined the Harvard Medical School as a postdoctoral research fellow. Her research focuses on the development of soft electronics including batteries, sensors, and bioelectronic devices.Lie Wang is currently a postdoctoral scholar at the Nanjing University. He received his PhD in Macromolecular Chemistry and Physics from the Fudan University in 2020. His research focuses on the development of flexible energy and electronic devices and their wearable applications.Yang Zhao is currently an associate professor in Northwestern Polytechnical University. He received his PhD degree in Macromolecular Chemistry and Physics from Fudan University in 2020. His research interests are focused on the development of flexible and multifunctional energy storage devices with high safety.Huisheng Peng is currently a university professor at Fudan University. His interest focuses on polymer fiber electronics. He has published over 300 papers and four books. Professor Peng has also obtained 79 licensed patents with 36 royally transferred to the industry.

• 1 Introduction to flexible batteries 2 Flexible thin-film lithium-ion batteries 3 Fiber lithium-ion batteries 4 Flexible aqueous lithium-ion batteries 5 Flexible aqueous sodium-ion batteries 6 Flexible aqueous zinc-ion batteries 7 Flexible lithium-air batteries 8 Flexible aluminum-air batteries 9 Stretchable Batteries 10 Integration of flexible batteries 11 Summary and Outlook

Ye Zhang is currently an associate professor at the College of Engineering and Applied Sciences at the Nanjing University. She received her Ph.D. degree in Macromolecular Chemistry and Physics from the Fudan University in 2018 and then joined the Harvard Medical School as a postdoctoral research fellow. Her research focuses on the development of soft electronics including batteries, sensors, and bioelectronic devices.Lie Wang is currently a postdoctoral scholar at the Nanjing University. He received his PhD in Macromolecular Chemistry and Physics from the Fudan University in 2020. His research focuses on the development of flexible energy and electronic devices and their wearable applications.Yang Zhao is currently an associate professor in Northwestern Polytechnical University. He received his PhD degree in Macromolecular Chemistry and Physics from Fudan University in 2020. His research interests are focused on the development of flexible and multifunctional energy storage devices with high safety.Huisheng Peng is currently a university professor at Fudan University. His interest focuses on polymer fiber electronics. He has published over 300 papers and four books. Professor Peng has also obtained 79 licensed patents with 36 royally transferred to the industry.

• 1 Introduction to flexible batteries 2 Flexible thin-film lithium-ion batteries 3 Fiber lithium-ion batteries 4 Flexible aqueous lithium-ion batteries 5 Flexible aqueous sodium-ion batteries 6 Flexible aqueous zinc-ion batteries 7 Flexible lithium-air batteries 8 Flexible aluminum-air batteries 9 Stretchable Batteries 10 Integration of flexible batteries 11 Summary and Outlook