Stabilizing hydrogen bonds and engineering multi-component hetero-solvation architecture for dendrite-free zinc metal anodes

Aqueous zinc-ion batteries (AZIBs) are promising candidates for renewable grid energy storage, but their development is limited by non-uniform zinc deposition, hydrogen evolution reactions (HERs), and byproduct growth at the zinc anode interface. Herein, a dual-regulation strategy integrating bulk solvation reorganization with interfacial dynamic electrostatic shielding is developed by introducing a trace amount of 1-butyl-3-methylimidazolium iodide (BMIMI, BI) into a Zn(OTf) 2 aqueous electrolyte. Multi-dimensional microscopic spectra and quantitative molecular dynamics simulations confirm that the co-incorporation of BMIM + cations and I − anions establishes a diversified I − -H 2 O-OTf − hetero-primary solvation sheath, disrupting the chemical degradation pathways caused by free water aggregation. Due to its electrostatic adsorption energy advantage on multiple crystal planes, BMIM + preferentially occupies active sites to form a dynamic cation shielding field. This forces Zn 2+ to diffuse away smoothly from local tip protrusions and induces lateral planar epitaxial growth along the dense (002) preferred crystal plane. Consequently, the electrolyte shows stability within the fundamental potential window during cyclic voltammetry tests, and the interfacial desolvation energy barrier decreases from 51.29 to 23.28 kJ mol −1 . This affords the Zn//Cu battery a stable Coulombic efficiency of 99.74%, and the Zn//Zn symmetric battery achieves a lifespan exceeding 7500 h under variable loads and high areal capacities. In full-cell applications, the cell maintains a capacity retention of 84.07% after 5000 cycles at a high current density of 2 A g −1 . Combined with ex-situ distribution of relaxation times and dynamic impedance evolution, this strategy confirms the feasibility of the system for industrial-grade variable-load energy storage scenarios.