Design of Cryogenic Electrolyte with Organic-Free Solvation Structure for Wide-Temperature Zinc Metal Batteries.

Abstract

Albeit the promising performance at ambient temperatures, the development of zinc metal batteries (ZMBs) is still haunted by the freezing-prone characteristic of aqueous electrolytes and the deteriorative interface reaction in extreme scenarios. Especially at low-temperature conditions, the abundant hydrogen bonds (H-bonds) between H2O molecules inevitably drive the aqueous solution transform into an orderly frozen state, resulting in sluggish reaction kinetics. Herein, a bio-inspired cryogenic electrolyte is proposed, and the strong interaction between proline additive and H2O solvent effectively disrupts the H-bond network, thereby depressing the freezing point while maintaining high ionic conductivity under extremely-low temperatures. Furthermore, the tailored weak and organic-free solvation structures facilitate rapid desolvation of Zn2+ ions, and the reduced H2O activity mitigates parasitic reactions on Zn anode surface, thus guaranteeing reversible zinc deposition and dendrite-free interface. Consequently, the anti-freezing electrolyte endows Zn||Zn cells with durable cyclic behavior over 2500 h. The PANI||Zn cell demonstrates excellent temperature adaptability from -30 to 60 °C, achieving a reversible capacity of 173.6 mAh g-1 at 60 °C and maintaining 93.6% capacity retention after 1300 cycles at -30 °C. This work reports a practical electrolyte design strategy for ZMBs in harsh environments, promoting the future application of low-temperature-resistant aqueous batteries.