Parallel Adsorption of Parts-per-Million Level Additives for Highly Efficient Aqueous Zinc-Ion Battery
Unstable zinc interfaces arising from dendrite growth and parasitic reactions impede the practical deployment of rechargeable aqueous zinc-ion batteries. This study introduces 1-(2-pyridylazo)-2-naphthol (PAN) as a parts-per-million (ppm) level electrolyte additive to stabilize the Zn anode. Theoretical and experimental analyses reveal that PAN undergoes parallel adsorption on the Zn surface, establishing strong π-π interactions between adjacent molecules that efficiently repel water. The OH, pyridine N, and azo N groups in PAN chelate Zn2+, modulating Zn2+ diffusion and promoting uniform deposition while suppressing dendrite formation. A 10 ppm (0.04 mM) PAN addition extends the lifespan of a symmetrical cell to 1500 h at 2 mA cm−2 and 1 mAh cm−2. The Zn||Cu half-cell achieves a Coulombic efficiency of 99.91% over 3500 cycles at 5 mA cm−2 and 1 mAh cm−2. Full cells with NH4V4O10 and MnO2 cathodes exhibit enhanced cycling stability. Notably, a Zn||NH4V4O10 pouch cell retains 71.1% capacity after 250 cycles at 0.8 A g−1. This work demonstrates a viable strategy for selecting high-efficiency additives for aqueous metal-based batteries.