A Critical Review of Electrolytes for Sodium‐Zinc Hybrid Ion Batteries: From Liquid to Solid

Aqueous hybrid Na‐Zn ion batteries (ASZIBs) have recently emerged as promising candidates for large‐scale energy storage due to their high safety and low cost. The evolution of electrolytes from liquid to quasi‐solid‐state and ultimately to all‐solid‐state structures determines the practical application prospects of ASZIBs. Liquid electrolytes exhibit high ionic conductivity; however, they are limited by narrow electrochemical stability window (ESW) and dendrite formation. Quasi‐solid‐state electrolytes (QSEs) have become the mainstream solution by mitigating leakage risks; however, they face the critical bottleneck of “uncontrolled dual‐ion transport,” which is characterized by concentration polarization and kinetic mismatch between Na + and Zn 2+ . This review focuses on strategies based on “single‐ion conductor” and “ion‐selective channel” designs to achieve accurate ion control. In addition, challenges regarding interfacial contact and room‐temperature (RT) ionic conductivity in all‐solid‐state electrolytes (ASEs) are discussed, thus providing theoretical insights for the development of high‐performance ASZIBs.