Breaking the Dependence on High Chloridion Concentration: A Four‐Electron Zn‐I 2 Batteries with Inorganic Colloid Electrolyte

ABSTRACT Four‐electron Zn‐I 2 batteries (4eZIBs) have attracted widespread attention owing to the high theoretical capacity (422 mA h g −1 ) and high safety, which is often dependent on the high‐concentration chloride‐containing electrolytes to motivate the sluggish I 0 →I + reaction kinetics. Besides, chloride corrosion of zinc metal anode, hydrolysis reaction of I + species, and high reactivity of free H 2 O molecules also significantly deteriorate the reversibility and cyclic stability of 4eZIBs. Herein, inorganic mineral colloid electrolyte is elaborately designed by homogeneously mixing attapulgite (AT) powder and seawater‐based ZnSO 4 solution (SW+ZSO+AT) to realize reversible 4eZIBs at a low chloride ion concentration condition (0.55 m ). Theoretical calculations manifest SW+ZSO+AT electrolyte contributes to the construction of a localized high‐concentration environment of Cl − ions and spatial confinement of H 2 O molecules. Experimental results suggest the optimized SW+ZSO+AT electrolyte delivers high ionic conductivity, low activation energy barrier, mild pH environment, and durable stability. The as‐assembled Zn||AC@I 2 batteries in the SW+ZSO+AT electrolyte achieved high‐rate capabilities of 343.6 mA h g −1 , 270.4 mA h g −1 , and 226.2 mA h g −1 at 0.5, 1, and 2 A g −1 , respectively. This study provides new insights to fabricate economical and practical electrolytes for 4eZIBs, and advances the design of mineral and seawater resources in reliable aqueous batteries.