It is generally believed that low-temperature Zn²⁺ plating/stripping efficiency is lower than at room temperature. However, theoretical and experimental results indicate that a reversal where low-temperature efficiency outperforms that at room temperature. Under the 3 mol·kg⁻¹ (3 m), Zn(ClO₄)₂ delivers 99.87% efficiency over 3800 cycles at −40 °C, far outperforming its room−temperature efficiency (94.92% over 110 cycles). Zn(BF₄)₂ achieves 99.76% over 3450 cycles at −40 °C versus 59.23% over 30 cycles at 25 °C. Above reversal phenomenon is closely related to anions (ClO₄^-, BF₄^-) with weak interactions toward H₂O and Zn²⁺, which minimize water aggregation around anions and reduce repulsion between inner−sphere Zn²⁺ and outer−sphere anions, promoting an anion−rich, water−poor outer solvation structure that disrupts the hydrogen−bond network and lowers the freezing point. Conversely, strong anion–water interaction (e.g., ZnCl₂) induces a water-rich structure with inferior low-temperature performance (−40 °C: 90.56% vs. 25 °C: 96.82%). To validate the above principle, Zn(CF₃SO₃)₂ and ZnSO₄ electrolytes were further employed for testing: the former forms anion−rich structure with superior low−temperature efficiency, while the latter forms water−rich structure with inferior efficiency. This work provides a general strategy for designing high−performance anti-freezing aqueous electrolytes.

LiNO₃ is known to significantly enhance the reversibility of lithium metal batteries; however, the modification of solvation structures in various solvents and its further impact on the interface have not been fully revealed. Herein, we systematically studied the evolution of solvation structures with increasing LiNO₃ concentration in both carbonate and ether electrolytes. The results from molecular dynamics simulations unveil that the Li⁺ solvation structure is less affected in carbonate electrolytes, while in ether electrolytes, there is a significant decrease of solvent molecules in Li⁺ coordination, and a larger average size of Li⁺ solvation structure emerges as LiNO₃ concentration increases. Notably, the formation of large ion aggregates with size of several nanometers (nano-clusters), is observed in ether-based electrolytes at conventional Li⁺ concentration (1 $\mathrm{M}$) with higher NO₃⁻ ratio, which is further proved by infrared spectroscopy and small-angle X-ray scattering experiments. The nano-clusters with abundant anions are endowed with a narrow energy gap of molecular orbitals, contributing to the formation of an inorganic rich electrode/electrolyte interphase that enhances the reversibility of lithium stripping/plating with Coulombic efficiency up to 99.71%. The discovery of nano-clusters elucidates the underlying mechanism linking ions/solvent aggregation states of electrolytes to interfacial stability in advanced battery systems.