High-entropy electrolytes for low-temperature zinc-ion hybrid capacitors

To deal with the low-temperature problems faced by aqueous zinc-ion hybrid capacitors (ZIHCs), such as increased viscosity, decreased ionic conductivity, and icing, high-entropy electrolytes (HEEs) are proposed and successfully prepared. By maximizing configurational entropy, the optimized HEEs consisted of multiple solvents (≥5 solvents) exhibit freezing points below −60 °C, suppressed hydrogen evolution, and regulated Zn²⁺ solvation structures, endowing dendrite-free Zn deposition and stable Zn||Zn symmetric cell cycling of 1000 h. The ZIHC employing the optimum HEE maintains over 80 % capacitance after 5000 cycles at −20 °C, delivering an energy density of 26.45 Wh kg⁻¹ with a wide voltage window of 2.0 V. The entropy-driven strategy disrupts water-dominated H-bond networks, enhances interfacial wettability, and balances ionic conductivity across temperatures. This work demonstrates the potential of high-entropy engineering to design adaptive electrolytes for extreme-condition energy storage, providing a promising approach for next-generation Zn-based energy storage devices.