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.

Deposition/dissolution-type cathodes can enable aqueous batteries to achieve high volumetric energy density, making them promising for large-scale energy storage systems (ESSs). However, developing low-cost materials with high deposition/dissolution efficiency remains challenging. Iron (Fe), the fourth most abundant element in the Earth’s crust, offers a cost-effective solution. Designing a battery system based on deposition/dissolution-type Fe cathode could significantly reduce EES costs. Inspired by this, a battery system with 1 M ZnSO₄ + 1 M FeSO₄ + 0.01 M H₂SO₄ (ZFH) electrolyte, graphite felt (GF) collector, and zinc anode is designed. As a result, the constructed half-cell exhibits a high cathode deposition/dissolution efficiency of about 100% and a flat discharge platform of 0.34 V vs. Ag/AgCl. Coupled with the zinc (Zn) anode, the Zn//GF full-cell stable cycling for over 2300 times with nearly 100% efficiency in the ZFH electrolyte. The discharging voltage reaches approximately 1.0 V at 5 mA·cm⁻². The electrochemical quartz crystal microbalance (EQCM) measurement combined with other technologies reveals the transformation mechanism between the Fe²⁺ and FeOOH·0.5H₂O on the GF cathode during electrochemical cycling. This strategy further reduces cost by adopting cheap elements, giving new insights into the cost-effective large-scale electrochemical energy storage systems.

The unstable zinc (Zn)/electrolyte interfaces formed by undesired dendrites and parasitic side reactions greatly hinder the development of aqueous zinc ion batteries. Herein, the hydroxy-rich sorbitol was used as an additive to reshape the solvation structure and modulate the interface chemistry. The strong interactions among sorbitol and both water molecules and Zn electrode can reduce the free water activity, optimize the solvation shell of water and Zn²⁺ ions, and regulate the formation of local water (H₂O)-poor environment on the surface of Zn electrode, which effectively inhibit the decomposition of water molecules, and thus, achieve the thermodynamically stable and highly reversible Zn electrochemistry. As a result, the assembled Zn/Zn symmetric cells with the sorbitol additive realized an excellent cycling life of 2000 h at 1 mA·cm^–2 and 1 mAh·cm^–2, and over 250 h at 5 mA·cm^–2 and 5 mAh·cm^–2. Moreover, the Zn/Cu asymmetric cells with the sorbitol additive achieved a high Coulombic efficiency of 99.6%, obtaining a better performance than that with a pure 2 mol·L^–1 ZnSO₄ electrolyte. And the constructed Zn/poly1, 5-naphthalenediamine (PNDA) batteries could be stably discharged for 2300 cycles at 1 A·g^–1 with an excellent capacity retention rate. This result indicates that the addition of 1 mol·L^–1 non-toxic sorbitol into a conventional ZnSO₄ electrolyte can successfully protect the Zn anode interface by improving the electrochemical properties of Zn reversible deposition/decomposition, which greatly promotes its cycle performance, providing a new approach in future development of high performance aqueous Zn ion batteries.