A MOF@ZnIn ₂ S ₄ Composite Quasi‐Solid Electrolyte for Highly Reversible Zn‐Ion Batteries

Abstract Zn‐ion batteries hold significant promise for large‐scale energy storage systems owing to their intrinsic safety and cost‐effectiveness. However, their practical deployment is hindered by uncontrolled dendrite growth and sluggish electrode reaction kinetics at metallic Zn anodes. To overcome these limitations, a quasi‐solid electrolyte (M@Z) based on a MOF@ZnIn 2 S 4 composite is presented. This innovative electrolyte exhibits high room‐temperature conductivity (0.99 mS cm −1 ) and an improved Zn 2+ transference number (0.54). The microporous MOF component ensures uniform Zn deposition and effectively suppresses dendrite formation. Meanwhile, the ZnIn 2 S 4 nanosheets wrapped around the MOF particles promote the formation of a beneficial In/ZnS‐contained interphase on Zn anodes during cycling, which mitigates side reactions and accelerates anode reaction kinetics. By virtue of the above merits, Zn symmetric cells achieve stabilized Zn plating/stripping over 3130 h with low overpotential and tolerate a high critical current density of 10 mA cm −2 . Furthermore, vanadium‐based full cells assembled with the M@Z electrolyte deliver exceptional cycling stability, with almost no capacity decay after 1000 cycles at 1.0 A g −1 .