In Situ Construction of Anode–Molecule Interface via Lone-Pair Electrons in Trace Organic Molecules Additives to Achieve Stable Zinc Metal Anodes

The practical application of aqueous zinc batteries (AZBs) is significantly limited by the poor reversibility of the zinc anodes, including rampant dendrite growth and severe interfacial side-reactions. Herein, trace hexamethylenetetramine (HMTA) additive with a lone-pair-electron containing heterocycle is introduced for Zn metal anode protection. Specifically, the trace added HMTA can change the solvated structure by strong interaction with zinc ions, and preferentially absorb on the anode surface to in situ establish an unique anode–molecule interface. Such an interface not only shows strong affinity to promote the dynamic transmission and deposition of Zn²⁺ ions but also displays a role in suppressing parasitic reactions. Consequently, a zinc anode in an electrolyte with trace HMTA achieves a high Coulombic efficiency of 99.75%, and delivers a remarkable lifespan over 4000 h at 5 mA cm⁻² and 1 mAh cm⁻² in a Zn//Zn symmetric cell. Even under a deep plating/stripping condition (5 mA cm⁻² and 5 mAh cm⁻²), it can still run almost for 600 h. Additionally, the Zn//V₂O₅ full cell with HMTA retains a high capacity retention of 61.7% after 4000 cycles at 5 A g⁻¹. Such an innovative strategy is expected to be of immediate benefit to design low-cost AZBs with ultra-long lifespan.