Highly Stable Quasi-Solid Thermocells for Continuous Power Generation Across a Broad Humidity Range.

Area of Science:

• Materials Science
• Energy Harvesting
• Electrochemistry

Background:

• Ionic hydrogel-based quasi-solid (IH-QS) thermocells offer potential for low-grade heat harvesting.
• However, their performance is limited by humidity-induced instability, causing dehydration or swelling.

Purpose of the Study:

• To develop humidity-stable IH-QS thermocells for reliable low-grade heat harvesting.
• To enhance the mechanical and thermoelectric performance of thermocells under varying humidity conditions.

Main Methods:

• Incorporation of amphiphilic networks and hygroscopic electrolytes into IH-QS thermocells.
• Utilizing hydrophilic SO3- groups and hydrophobic phenyl moieties for water retention and swelling suppression.
• Leveraging electrostatic and ion-π interactions to enhance thermopower.

Main Results:

• Achieved operational stability across a wide relative humidity (RH) range (30%-99%).
• Demonstrated high thermopower (e.g., 2.17 mV K⁻¹ at 30% RH) and normalized power density (e.g., 0.19 mW m⁻² K⁻² at 30% RH).
• Maintained significant performance at high humidity (1.63 mV K⁻¹ and 0.55 mW m⁻² K⁻² at 99% RH).

Conclusions:

• The developed IH-QS thermocells exhibit enhanced stability and performance under diverse humidity conditions.
• This advancement overcomes a critical limitation for the practical deployment of thermocell technology.
• The synergistic design offers a promising pathway for efficient low-grade heat energy harvesting.