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

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Conventional battery electrolytes face performance degradation and failure in extreme temperature environments.
• The properties of electrolytes are a key limitation in extending battery operating temperature ranges.
• Zinc-ion batteries are promising for energy storage but are sensitive to temperature fluctuations.

Purpose of the Study:

• To propose a novel entropy-driven hydrated eutectic electrolyte (HEE) for zinc-ion batteries.
• To expand the operating temperature range of zinc-ion batteries through electrolyte engineering.
• To enhance both low-temperature anti-freezing ability and high-temperature thermal stability.

Main Methods:

• Development of a hydrated eutectic electrolyte (HEE) with diverse Zn2+ solvation configurations.
• Characterization of solvation configurational entropy and its impact on electrolyte properties.
• Testing of full cells using the HEE across a wide temperature range (-40°C to +80°C).

Main Results:

• The HEE exhibits over 40 types of Zn2+ solvation structures, significantly increasing configurational entropy compared to conventional electrolytes.
• High ionic conductivity (0.42 mS/cm) is maintained at -40°C, demonstrating excellent anti-freezing properties.
• The electrolyte shows enhanced thermal stability above +140°C and enables stable full-cell cycling over -40°C to +80°C.

Conclusions:

• The entropy-driven hydrated eutectic electrolyte effectively expands the operating temperature range of zinc-ion batteries.
• The HEE demonstrates remarkable cycling stability at both ultralow (-40°C, 1500 cycles, 100% retention) and elevated (+80°C, 1000 cycles, 72% retention) temperatures.
• This entropy-driven electrolyte design offers significant potential for developing batteries adapted to extreme temperature environments.