Spatiotemporal synergy of a coordination decomposition bifunctional strategy for ultra-stable aqueous zinc anodes

Aqueous zinc-ion batteries (AZIBs) face a critical bottleneck originating from the intrinsic interplay between solvated water reactivity and uncontrolled interfacial nucleation, which collectively trigger hydrogen evolution and dendrite formation on the Zn anode. Herein, we propose a spatiotemporal decoupling approach. Two complementary agents, namely PEGDME and FEC, are co-introduced into a conventional ZnSO₄ electrolyte, achieving synergistic modulation across spatial and temporal scales. In the spatial dimension, the highly Lewis basic PEGDME selectively resides in the primary Zn²⁺ solvation sheath. Via multidentate Zn-O bonding, it expels active water species and thus markedly reduces the HER in the bulk electrolyte. Meanwhile, PEGDME assumes a flat lying orientation on the Zn(002) basal plane, accelerating lateral surface migration of Zn adatoms while inhibiting three dimensional dendritic nucleation. In the temporal domain, the electron withdrawing fluorine substituents confer FEC with a reduced LUMO level and attenuated Lewis basicity, which hinders its competition for the inner coordination sphere. Consequently, FEC preferentially adheres to surface irregularities such as step edges, and subsequently decomposes reductively to generate a ZnF₂ rich solid electrolyte interphase (SEI). This in situ formed SEI continuously deactivates parasitic sites, suppresses the HER, and directs homogeneous Zn plating. Through this functional decoupling where PEGDME governs solvation regulation and surface diffusion, while FEC is responsible for defect passivation and interface stabilization, the fundamental suppression of the HER and dendrite growth is achieved. Experimental results demonstrate that the Zn//Zn symmetric battery achieves stable cycling for over 1100 hours at 1 mA cm^-2 and 1 mA h cm^-2, while the Zn//Cu asymmetric battery delivers an average coulombic efficiency (CE) as high as 99.2% over 200 cycles. This work presents a novel paradigm for the synergistic design of solvation engineering and interface engineering, offering an effective pathway for constructing ultra-stable aqueous zinc anodes.