Molecular Regulation of Zn2+ Solvation Structure and Interphase Evolution by Glutaronitrile for Stable Aqueous Zinc Metal Batteries

Aqueous zinc metal batteries are promising for safe and cost-effective energy storage. However, their practical application is limited by the intrinsic instability of the Zn/electrolyte interface, including water-induced hydrogen evolution, Zn corrosion, and dendrite-prone Zn deposition. Herein, glutaronitrile (GLN) is introduced as a multifunctional dinitrile additive to stabilize Zn metal anodes through coupled regulation of solvation chemistry and interfacial evolution. The polar C≡N groups of GLN can coordinate with Zn2+, to replace part of the water molecules in the primary solvation shell, thereby suppressing the activity of coordinated water. Meanwhile, uncoordinated C≡N groups act as hydrogen-bond acceptors to reorganize the surrounding water network, further suppressing free-water participation in hydrogen evolution and corrosion. This dual regulation optimizes the Zn/electrolyte interfacial environment, improves electrolyte wettability on Zn, homogenizes Zn2+ flux, and promotes compact, dendrite-suppressed Zn deposition. Additionally, GLN promotes the formation of a chemically heterogeneous interfacial structure enriched with ZnF2 in the inner region, which further protects the Zn surface and stabilizes the Zn plating/stripping process. The optimized ZHG6 electrolyte enables Zn||Zn symmetric cells to cycle stably for over 900 h at 1 mA cm−2 and 1 mAh cm−2, while Zn||Cu cells maintain high Coulombic efficiency during long-term cycling. Furthermore, Zn||V6O13 full cells exhibit enhanced cycling stability and rate capability, achieving stable operation for 3200 cycles at 5 A g−1. As evidenced in this work, dinitrile-based molecular additives provide an effective and scalable strategy to fabricate durable aqueous zinc metal batteries.