Recent progress in advanced flexible zinc ion battery design

Flexible zinc ion batteries are a promising energy supply for flexible and wearable electronic devices due to their high theoretical capacity, superior safety, low cost, and eco-friendliness. The rational design of highly efficient flexible zinc ion batteries with high electrochemical performance, long cycling life, and excellent mechanical deformability is still a formidable challenge, limiting their widespread application in flexible electronics. This paper summarizes the recent progress in designing and fabricating flexible zinc ion batteries from three aspects: device configurations, battery constituent components, and practical applications. First, we introduce the energy storage mechanism and summarize modification strategies of constituent components, including current collector, zinc anode, cathode, and solid/gel electrolyte, revealing their positive effects on the performance of flexible zinc ion batteries. Then, we elucidate advanced device configurations for flexible zinc ion batteries such as sandwich-type, planar, and fiber-type structures, followed by discussion on the specific properties of flexible zinc ion batteries that enhance their adaptability in practical applications, such as integration with electronics, self-healing ability, resistance to extreme conditions, and responsiveness to environments. The current challenges and outlooks are also presented.