Solvent-free protic liquid enabling batteries operation at an ultra-wide temperature range

Area of Science:

• Materials Science
• Electrochemistry
• Chemical Engineering

Background:

• Commercial batteries rely on liquid electrolytes, which present limitations such as narrow electrochemical windows, flammability, and restricted operating temperatures.
• These inherent drawbacks hinder battery performance and safety, particularly in demanding applications.

Purpose of the Study:

• To develop a novel solvent-free protic liquid electrolyte using polyphosphoric acid.
• To address the limitations of conventional liquid electrolytes and enhance battery safety and performance across a wide temperature range.

Main Methods:

• Investigated polyphosphoric acid as a solvent-free electrolyte.
• Evaluated its electrochemical stability window, nonflammability, and working temperature range.
• Tested a MoO3/LiVPO4F rocking-chair battery utilizing the novel electrolyte from 0°C to 250°C.

Main Results:

• Polyphosphoric acid demonstrated nonflammability, a wide electrochemical stability window (>2.5 V), low volatility, and an extensive working temperature range (>400°C).
• The MoO3/LiVPO4F battery operated effectively between 0°C and 250°C, achieving a high power density of 4975 W kg⁻¹ at 100°C.

Conclusions:

• Solvent-free polyphosphoric acid offers superior performance and safety compared to traditional electrolytes.
• This research presents a viable pathway for designing stable, safe, wide-temperature electrolytes for batteries operating under extreme conditions.