Decoupling interfacial water activity and bulk ion transport via a cellulose–ionic liquid microenvironment for ultra-stable aqueous zinc batteries

Electrolyte strategies that suppress active water in aqueous zinc batteries often compromise ionic transport, creating a long-standing trade-off between interfacial stability and fast Zn 2+ kinetics. Here we show that dissolving cellulose in the ionic liquid creates a hydrogen-bond-regulated electrolyte microenvironment that breaks this trade-off. Rather than simply increasing hydrophobicity, the cellulose–ionic liquid microenvironment reorganizes hydrogen-bonded water and Zn 2+ solvation, thereby constraining active water while preserving ion-transport pathways. As a result, the ionic conductivity of the baseline Zn(OTF) 2 electrolyte increases from 7.2 to 13.7 mS cm –1 , whereas the ionic liquid alone lowers it to 3.1 mS cm –1 , revealing a cellulose-enabled reversal of the conventional transport penalty. This cooperative microenvironment couples bulk solvation/clustering regulation with the formation of a water-deficient, anion-enriched interphase on the Zn anode. These effects lower the apparent interfacial barrier, promote uniform Zn deposition, and induce an inorganic-rich hybrid interphase. Consequently, Zn symmetric cells operate for over 10,000 h, Zn//Cu cells deliver an average Coulombic efficiency of 99.7% over 2,500 cycles, and Zn//NaV 3 O 8 ·1.5H 2 O full cells retain 77.8% of their capacity after 100 cycles at an ultralow N/P ratio of 1.5. This work provides a design framework for decoupling active-water suppression from bulk ion transport toward practical aqueous Zn-metal batteries.