Electrolyte Evolution for Flexible Energy Storage Systems: From Liquid to Solid, from Rigid to Soft, and from Organic to Aqueous

With the rapid development of modern electronic devices and the diversification of use scenarios, flexible energy storage systems (FESS) have gained widespread attention as an inseparable part of electronic devices. Electrolyte is considered as one of the most influential components of tremendous scientific and commercial interest in the performance of FESS. Electrolytes are undergoing tremendous structural variations from liquid to solid, rigid to flexible, and organic to aqueous to meet the evolving requirements for FESS. This review delineates the evolutionary trajectory of electrolyte development across three dimensions: transitioning from liquid to solid, from rigid to flexible, and from organic to aqueous formulations. Furthermore, it elucidates potential mechanisms influencing the electrochemical stability and interfacial properties of electrolytes, along with their impact on battery performance. Subsequently, various strategies are outlined to address these challenges and advance the development of FESS electrolytes. Lastly, the functionality and structural design, computation methods, compatibility (integration) of the FESS are evaluated, followed by a comprehensive summary and outlook. We believe this article will aid researchers in comprehending the underlying causes of these challenges and in designing cutting-edge flexible solid-state electrolytes for assembling FESS that exhibit compatibility and superior performance.