High-performance solid-state electrochemical thermal switches with earth-abundant cerium oxide

Area of Science:

• Materials Science
• Solid-State Chemistry
• Nanotechnology

Background:

• Electrochemical switches modulate heat flow by altering thermal conductivity (κ) of active metal oxide films.
• Previous devices exhibited limited performance with low on/off κ-ratios (<5) and narrow switching widths (<5 W/m·K).

Purpose of the Study:

• To develop high-performance solid-state electrochemical thermal switches.
• To investigate the use of cerium dioxide (CeO2) thin films for improved thermal switching capabilities.

Main Methods:

• Fabrication of a CeO2 thin film on a YSZ solid electrolyte substrate.
• Electrochemical cycling (reduction and oxidation) to modulate the thermal conductivity of the CeO2 film.
• Measurement of thermal conductivity in both reduced (off-state) and oxidized (on-state) conditions.

Main Results:

• Achieved a thermal conductivity of ~2.2 W/m·K in the reduced (off-state) and 12.5 W/m·K in the oxidized (on-state) CeO2 film.
• Demonstrated a stable on/off κ-ratio of 5.8 and a switching width of 10.3 W/m·K over 100 cycles.
• The CeO2-based switch shows enhanced performance compared to previous electrochemical thermal switches.

Conclusions:

• CeO2-based solid-state electrochemical thermal switches offer superior performance for thermal management.
• These devices show potential for applications in thermal shutters and thermal displays.
• The electrochemical switching mechanism provides a viable route for tunable thermal conductivity materials.