Achieving stable Zn metal anode through novel interface design with multifunctional electrolyte additive

Rechargeable aqueous Zn batteries (RAZBs) are promising for energy storage systems as they are intrinsically safe, cost-effective and environmentally friendly. However, undesired dendrites and corrosion side reactions worsen at cycling, which limit the reversibility and scalable application of RAZBs. This issue arises from the undesired side reactions from corrosion of Zn in regular aqueous electrolytes, which lead to formation of side products, nonuniform Zn nucleation, finally dendrite formation. Here, we report nitrilotriacetic acid (NTA) as a highly efficient functional additive that can preferentially adsorbs on Zn surface, avoiding the direct contact between Zn and water molecules and significantly alleviating corrosion. This clean, protected Zn surface can thus promote uniform Zn plating/stripping. Furthermore, the adsorbed NTA molecules can attract water molecules to facilitate the desolvation of Zn2+ and promote Zn2+ fast transport, as verified both experimentally and computationally. Notably, we found that only a trace amount of NTA (0.15 wt%) is sufficient to form a stable electrode/electrolyte interface, reducing the corrosion rate from 3.63 mA cm−2 to merely 0.22 mA cm−2. This stable interface enabled highly reversible Zn stripping/plating at 5 mA cm−2 and 0.5 mAh cm−2 in symmetric cells, lasting about 2100 h. An outstanding average Coulombic efficiency of 99.40 % in 800 cycles was also achieved. This study provides new insights into realizing highly reversible Zn anodes for RAZBs via the addition of highly efficient, multifunctional electrolyte additive, whose design principle may be generalized to many rechargeable battery systems.