Orchestrating dual-interface stabilization via a threefold mechanistic synergy of aluminum dihydrogen phosphate for ultrastable aqueous zinc-ion batteries

Abstract

Aqueous zinc-ion batteries (AZIBs) are plagued by dendrite proliferation, parasitic hydrogen evolution, and cathode degradation, which stem intrinsically from high water activity and the inherent instabilities of the electrode interfaces. Herein, we demonstrate a trace aluminum dihydrogen phosphate (Al(H2PO4)3, ADP) additive to construct a robust “liquid-field-interface” triple-defense system, fundamentally reconfiguring the electrolyte chemistry through a cation-anion synergistic mechanism. In the bulk electrolyte, H2PO4- anions reconstruct the Zn2+ solvation sheath, suppressing free water activity and lowering the desolvation energy barrier. Across the electric field, Al3+ cations preferentially adsorb onto high-field protrusions to form a positive repulsive layer. This homogenizes the Zn2+ flux and compresses the electric double layer to boost charge transfer kinetics. At the dual interfaces, the additive simultaneously forms a water-blocking Zn3(PO4)2 SEI on the anode and mitigates Mn dissolution at the cathode. Enabled by this multi-level regulation, Zn||Zn symmetric cells exhibit an ultralong lifespan of 6000 h at 1 mA cm-2 (0.5 mAh cm-2), and Zn||MnO2 full cells demonstrate superior cycling stability with 94.1% capacity retention after 1000 cycles. This work establishes a scalable anion-cation synergistic paradigm that synergistically resolves interfacial instabilities, providing a versatile and robust solution for the practical realization of long-duration AZIBs.