Using Acetone as a Monosolvent for Ultralow Temperature Supercapacitors at -70 °C

Area of Science:

• Materials Science
• Electrochemistry
• Chemical Engineering

Background:

• Commercial supercapacitors have a low operating temperature limit of -50°C, insufficient for extreme applications like polar resource exploitation (-60°C) and near-space exploration (-70°C).
• Existing cosolvent strategies improve operating temperature but suffer from low conductivity, high desolvation energy, and increased production costs.

Purpose of the Study:

• To develop a novel low-temperature electrolyte using acetone (ACT) as a monosolvent.
• To address the limitations of conventional supercapacitor electrolytes in extreme temperature conditions.

Main Methods:

• Investigated acetone's properties: medium dielectric coefficient (ε=20.9), low donor number (10.67), and ultralow melting point.
• Fabricated and tested supercapacitors utilizing ACT-based electrolytes.
• Evaluated electrochemical performance, including capacitance retention, cycling stability, power density, and energy density across a wide temperature range.

Main Results:

• ACT demonstrates strong ion-dissociation and weakened ion-solvent interactions, facilitating rapid ion transport and desolvation.
• Supercapacitors with ACT-based electrolytes achieved 86.5% capacitance retention from 20°C to -70°C.
• The devices exhibited high cycling stability (97.75% after 13,000 cycles) and excellent power/energy densities (3776 W kg⁻¹ @ 14.16 Wh kg⁻¹).

Conclusions:

• Acetone is a promising monosolvent for developing high-performance, low-temperature supercapacitor electrolytes.
• The ACT-based electrolyte offers a superior operating temperature range, enhanced stability, and cost-effectiveness.
• This advancement holds significant potential for energy storage in extreme environments due to low toxicity and production costs.