Molecular Scalpel for Solvation Sheath Surgery: Trace Phosphocholine Chloride Sodium Mediates Dual-Interface Regulation Toward Ultra-Stable Aqueous Zinc-Ion Batteries

Abstract

Uncontrollable and harmful Zn-metal chemistry occurring at the electrode/electrolyte interface significantly impedes the widespread commercialization of aqueous zinc-ion batteries (AZIBs). Herein, a biocompatible phosphocholine chloride sodium salt (PCS) as a trace additive is introduced into the traditional ZnSO₄ aqueous electrolyte, effectively stabilizing the dual interfaces at both the anode and cathode sides. The hydrophobic choline moieties and the zincophilic phosphate groups within PCS spontaneously assemble a compact interfacial bilayer on the zinc anode surface, synergistically guiding the uniform deposition of Zn²⁺ and preventing water adsorption. The PCS can reorganize the Zn²⁺ solvation structure and capture free water through enhanced strong hydrogen bonds, thereby inhibiting interface corrosion and hydrogen evolution reaction. Furthermore, the adsorption of PCS on the cathode surface not only greatly maintains the integrity of the cathode structure but also enhances the long-cycle stability of the full cells. Consequently, the symmetric Zn//Zn cell achieves a remarkable cumulative capacity of 17.5 Ah cm⁻² with outstanding durability over 7002 h at 5 mA cm⁻². The Zn//Cu asymmetric cell maintains a 99.89% average coulombic efficiency upon 6576 cycles at 1 mA cm⁻², demonstrating high reversibility. Notably, the Zn//NaV₃O₈⋅1.5H₂O full cell demonstrates 83.56% capacity retention after 3000 cycles at 5 A g⁻¹. This work provides a regulation strategy for the bilateral interfaces to achieve highly stable AZIBs.