Unraveling Spatial Electrochemical Heterogeneity and Additive‐Mediated Regulation in Scale‐up Aqueous Zinc‐Ion Pouch‐Type Cells

Abstract

ABSTRACT Scaling aqueous zinc‐ion batteries (AZIBs) to pouch‐type configurations amplifies electric‐field and Zn 2+ flux heterogeneities, causing non‐uniform Zn deposition. Here, β‐cyclodextrin (β‐CD) and Tween 80 (Tw80) are systematically investigated to decouple bulk transport and interfacial kinetic regulation in scale‐up pouch‐type cells. β‐CD increases ionic conductivity (3.44 to 5.95 mS cm − 1 ) and the Zn 2+ transference number (0.16 to 0.47), promoting uniform bulk ion flux and extending symmetric pouch‐type cell lifespan beyond 1000 h at 1 mA cm − 2 . Conversely, Tw80 operates via interfacial adsorption to regulate local reaction kinetics, achieving stable cycling for >600 h. Spatially resolved analysis, operando Raman spectroscopy, and in situ thermal imaging reveal that β‐CD suppresses macroscopic heterogeneity across near‐tab, central, and edge regions by stabilizing bulk solvation, whereas Tw80 mitigates localized interfacial instability. In practical Zn||V 2 O 5 pouch‐type full cells, β‐CD delivers superior long‐term capacity retention, while Tw80 excels under high‐rate conditions. This work identifies spatial electrochemical heterogeneity as a primary scaling limit and offers general design principles connecting additive chemistry, transport kinetics, and format‐dependent deposition for practical AZIBs.