Entropy-Driven Hydrated Eutectic Electrolytes with Diverse Solvation Configurations for All-Temperature Zn-ion Batteries.

ABSTRACT

Batteries always encounter uncontrollable failure or performance decay under extreme temperature environments, which is largely limited by the properties of electrolytes. Herein, an entropy-driven hydrated eutectic electrolyte (HEE) with diverse solvation configurations is proposed to expand the operating temperature range of Zn-ion batteries. The HEE possesses over 40 types of Zn2+ solvation structure with uniform distribution, contributing to its much higher solvation configurational entropy compared to the conventional aqueous counterpart (only 6 types). These effectively promote its anti-freezing ability under ultralow temperatures, with a high ionic conductivity of 0.42 mS cm-1 even at a low temperature of -40 °C. Moreover, the entropy-driven property can simultaneously enhance the thermal stability under a high temperature over +140 °C. Therefore, the HEE can enable full cells stably working over a wide temperature range of -40~+80 °C, performing over 1500 cycles with 100 % capacity retention at -40 °C and 1000 cycles with ~72 % capacity retention at +80 °C. This inspiring concept of entropy-driven electrolyte with quantized solvation configurational entropy value has charming potential for designing future special batteries with excellent adaptability towards extreme temperature environments.