Tailoring tetrahedral and pair-correlation entropies of glass-forming liquids for energy storage applications at ultralow temperatures

Aqueous solution experiences either crystallization or vitrification as being cooled, yet the mechanism of this bifurcation is confused. Since the glass-transition temperature Tg is much lower than the melting temperature, we herein propose an entropy-driven glass-forming liquid (EDGFL) as an attractive concept to develop anti-freezing electrolytes. The Tg is delicately modulated via regulating local structural orders to avoid the energy-driven ice crystallization and enter an entropy-driven glass transition, which can be theoretically explained by the competitive effect between tetrahedral entropy of water and pair correlation entropy related to ions. The constructive EDGFL with a low Tg of −128 °C and a high boiling point of +145 °C enables stable energy storage over an ultra-wide temperature range of −95~+120 °C, realizes superior AC linear filtering function at −95 °C, and helps improve the performance of aqueous Zn-ion batteries at ultralow temperatures. This special electrolyte will provide both theoretical and practical directions for developing anti-freezing energy storage systems adapting to frigid environment. Aqueous solutions that can enter glassy state have excellent anti-freezing property. Here the authors propose a glass-forming liquid by tailoring tetrahedral and pair-correlation entropies to achieve ultralow temperature energy applications.