Development of Electrolytes towards Achieving Safe and High‐Performance Energy‐Storage Devices: A Review

Abstract Increasing interest in flexible/wearable electronics, clean energy, electrical vehicles, and so forth is calling for advanced energy‐storage devices, such as high‐performance lithium‐ion batteries (LIBs), which can not only store energy efficiently and safely, but also possess additional properties, such as good mechanical properties to bear deformations or even to be used as structural components. These expectations first indicate the directions, but also raise new challenges for the advancement of energy materials. As one of the critical components in LIBs, the electrolyte connecting the two electrodes is vital for achieving the desired performances in batteries. In this Review, the developments of various liquid electrolytes (organic, ionic liquid, and aqueous electrolytes), solid electrolytes (solid polymer and inorganic solid), as well as gel electrolytes is briefly summarized and discussed. For each type of electrolyte, the challenging issues and possible solutions are discussed. In particular, safety, ionic conductivity, and contact/interface issues are emphasized. Finally, from a composite point of view, strategies for the development of high‐performance electrolytes with all‐round properties are proposed.