Zn-Alloying Sites with Self-Adsorbed Molecular Crowding Layer as a Stable Interfacial Structure of Zn Electrodes

Rechargeable aqueous zinc (Zn) metal batteries (ZMBs) have gained tremendous attention because of their intrinsic safety and low cost. However, the lifespan of ZMBs is seriously limited by severe Zn dendritic growth in aqueous electrolytes. Despite the feasibility of Zn deposition regulation by introducing Zn-alloying sites at the Zn plating surface, the activity of the Zn-alloying sites can be seriously reduced by side reactions in the aqueous environment. Here, we propose a facile but efficacious strategy to reinforce the activity of the Zn-alloying sites by introducing a low quantity of polar organic additive in the electrolyte that can be self-adsorbed on the Zn-alloying sites to form a molecular crowding layer against the parasitic water reduction during Zn deposition. As a consequence, stable cycling of the Zn anode can be maintained at such a multifunctional interfacial structure, arising from the synergism between the seeded low-overpotential Zn deposition on the stabilized Zn-alloying sites and a Zn²⁺ redistributing feature of the self-adsorbed molecular crowding layer. The interfacial design principle here can be widely employed due to the great variety of Zn-alloy and polar organic materials and potentially be applied to improve the performance of other aqueous metal batteries.