Achieving dendrite-free zinc deposition by large-size anion-reinforced solvated structures for highly reversible zinc anode

Abstract

The electrochemical instability of zinc anode caused by surface side reactions and irregular zinc deposition severely hinders the practical application of aqueous zinc ion batteries (AZIBs). In this work, diethylenetriaminepentaacetic acid, pentasodium salt (DTPA) was used as a novel electrolyte additive to modulate the electrochemical stability of Zn anode. The DTPA anion can strongly coordinate with Zn²⁺, thus enabling the formation of a unique large-size anion-enhanced solvation structure of electrolyte. In this, not only the generation of by-products on Zn anode can be effectively inhibited, but more importantly, the deposition kinetics of Zn²⁺ can be well regulated to induce even and stable zinc deposition. In addition, DTPA is more prone to chemically adsorbed on the surface of Zn anode than H₂O, contributing to the resistance of electrochemical corrosion. Synergistically, the Zn anode demonstrates excellent cycling stability (3850 h at 1 mA cm⁻²_, 1 mAh cm⁻², and 500 h at 10 mA cm⁻²_, 10 mAh cm⁻²), enhanced coulombic efficiency (99.83% upon 3500 cycles at 5 mA cm⁻²_, 1 mAh cm⁻²), and high reversibility of 1050 h even at a stringent discharge depth of 80%. Particularly, the full cell assembled with NaV₃O₈·1·5H₂O (NaVO) cathode can also operate stably for 1800 cycles at 2 A g⁻¹ with a high capacity retain of 90.8%. This work may pave a new route to achieve high-performance AZIBs by regulating the deposition process of Zn²⁺ based on large-size anion-enhanced solvation structure of electrolyte.