Co‐Regulation of Interface and Bulk for Enhanced Localized High‐Concentration Electrolytes in Stable and Practical Zinc Metal Batteries

Abstract

Abstract Rechargeable zinc metal batteries (RZMBs) are promising for energy storage due to their high capacity and cost‐effectiveness. However, their commercialization is hindered by challenges including dendrite growth, parasitic reactions, and cathode degradation, particularly under low current densities and negative/positive (N/P) capacity ratios. Localized high‐concentration electrolytes offer potential solutions, but their reliance on high salt concentrations to replicate solvation structures of high‐concentration electrolytes limits their practicality, due to diluent's inherent inertness that limits its role in interfacial chemistry. Here, we present a co‐regulation strategy that integrates bulk and interfacial properties to develop an interfacial‐enhanced localized high‐concentration electrolyte (ILHCE). By incorporating non‐coordinating 1,4‐dioxane diluent and 1‐ethyl‐3‐methylimidazolium (emim + ) cations into dilute aqueous electrolytes, dioxane molecules are pulled into electric double layer (EDL) through the interaction between emim + and dioxane, achieving a pronounced dilution effect from bulk electrolyte to the EDL. This generates an anion‐rich and water‐depleted EDL at both anode and cathode interfaces, enhancing Zn 2+ transport dynamics, ensuring cathode stability and deriving a robust anion‐derived solid‐electrolyte interphase. Full batteries using Mn 0.5 V 6 O 13 cathodes with a low N/P ratio of 1.77 demonstrate 80% capacity retention over 300 cycles at 0.2 A g −1 , highlighting ILHCE as a transformative electrolyte design toward real‐world applications.