Novel organic additives with high dipole moments: Improving the anode interface structure to enhance the performance of zinc ion aqueous batteries.

The reversibility and stability of aqueous zinc-ion batteries (AZIBs) are largely limited by free-water-induced side reactions (e.g., hydrogen evolution and zinc corrosion) and negative zinc dendrite growth. To address these issues, we introduced triethyl 2-phosphonopropionate (Tp), a novel high-dipole-moment electrolyte additive. Tp effectively replaces free water in the electrolyte through strong ion-dipole interactions, altering the solvation structure and suppressing hydrogen evolution and zinc corrosion at the zinc anode. Additionally, the high binding energy between Tp and zinc foil ensures that Tp adheres firmly to the zinc anode surface, while the hydrophobic alkyl chains repel free water, modifying the interfacial structure of the zinc anode, promoting reversible zinc deposition, and effectively suppressing zinc dendrite growth. With these excellent properties, the optimal concentration of Tp enables a cycle time of over 770 h for 1 mA cm and 1 mAh cm symmetric cells, which is 7.7 times longer than that of pure electrolyte. Furthermore, the cycle number of Zn//NaVO full cells increased from 600 to 4000 cycles compared to pure electrolyte, with capacity retention improved from 70 % to 92 %. These results highlight the significance of high-dipole moment electrolyte additives, provide new insights into electrolyte modification strategies, and are expected to accelerate the commercialization of AZIBs for practical applications.