Self‐Stratifying Electrolyte Enables Triple‐Interface Regulation for Highly Reversible Zn Metal Batteries

Abstract

ABSTRACT Aqueous zinc metal batteries (AZMBs) are challenged by the incompatibility between cathode kinetic demands and Zn‐anode interfacial stability in homogeneous electrolytes. Biphasic electrolytes can spatially decouple the two electrode environments, yet the accompanying liquid/liquid interface often suffers from active‐water crossover and sluggish interfacial ion transport. Herein, a self‐stratifying electrolyte is developed to realize triple‐ interface regulation across the cathode/electrolyte, liquid/liquid, and Zn/electrolyte interfaces. In this design, dimethyl carbonate (DMC) serves as a salt‐solvating solvent to facilitate Zn 2+ transfer and regulate solvation evolution across the biphasic interface, whereas methyl (2,2,2‐trifluoroethyl) carbonate (FEMC) acts as a water‐excluding solvent to suppress active‐water crossover and stabilize Zn‐side interfacial chemistry. Together, they disrupt the hydrogen‐bond network of free water, induce a water‐shielding electrical double layer, and promote a robust organic–inorganic gradient interphase on the Zn anode. Consequently, highly reversible Zn plating/stripping and markedly improved full‐cell performance are achieved, including over 2500 h cycling in Zn||Zn cells and enhanced stability in Zn||PANI and Zn||MnO 2 full cells. This work establishes a triple‐interface regulation strategy for highly reversible AZMBs and provides a new design principle for advanced biphasic electrolytes.