Antifreeze Protein Mimics Realizing Stable Low-Temperature-Resistant Aqueous Zn-Ion Batteries with High Water Content

Rechargeable aqueous metal batteries offer inherent safety and low cost due to the predominance of water in their aqueous electrolytes, yet their practical applications are severely limited by electrolyte freezing under subzero conditions. Drawing inspiration from the mechanism of antifreeze proteins (AFPs) that protect living organisms from freezing damage, we synthesize oxidized quasi-carbon nitride quantum dots (OQCNs) featuring a regularly in-plane structure commensurate with the prism face of hexagonal ice crystal. At an ultralow concentration, the as-synthetic OQCNs effectively mimic AFP functionalities by controlling ice crystal morphology, suppressing ice growth kinetics, and inhibiting ice recrystallization. This synergistic mechanism preserves continuous ion transport pathways while mitigating physical damage to battery components caused by ice crystal growth. Molecular dynamics simulations demonstrate that the Gibbs-Thomson effect underpins the suppression of ice growth, avoiding complete solidification of the electrolyte under subzero conditions. The OQCNs-modified electrolyte exhibits exceptional cryogenic performance at -30 °C, with Zn||Zn symmetric cell maintaining stable cycling of 1000 h and Zn||NH₄ ⁺-intercalated vanadium oxide (NVO) battery preserving 91.48% capacity retention through 5000 cycles (over 90 days). This work unveils a bioinspired paradigm that significantly enhances the performance of eco-friendly, high-moisture electrolytes, paving the way for robust, low-temperature-resistant zinc-ion batteries and related aqueous electrolyte-based technologies.