Entropy-Driven Polymer-like Aqueous Electrolytes with Ultra-Low Glass Transition Temperature for Aqueous Zinc-Ion Batteries at Low Temperatures

The development of aqueous batteries, such as zinc-ion batteries, is attracting ever-increasing attention, especially in the area of electrolyte engineering. However, conventional aqueous batteries usually suffer from slow kinetics and electrolyte crystallization at low temperatures. Herein, we, for the first time, propose a polymer-like aqueous electrolyte (PLE) with fast kinetics by modifying Marcus theory parameters (dielectric constant). The PLE benefits from the coordination of multiple low-polarity molecules with low dielectric constants around zinc, resulting in an ultra-low glass transition temperature (the liquid state at –110 °C) and fast low-temperature kinetics (an overpotential of less than 0.35 V at –60 °C and 0.5 mA cm–2). Meanwhile, high-entropy-engineered solvents reconstruct the solvation sheath in the electrolyte system, reduce the solvation recombination energy, and significantly promote the reversible cycle of the zinc anode (exceeding 8000 h at 0.1 mA cm–2). More practically, even at a low temperature of –40 °C, the polyaniline||Zn cell exhibits one of the best performances. This work provides a rational strategy for aqueous energy storage for the exploration of extraterrestrial survival at ultra-low temperatures.