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

TL;DR

This paper presents a high-performance solid-state electrochemical thermal switch using cerium oxide thin films, achieving an on/off thermal conductivity ratio of 5.8 with potential applications in thermal management devices.

Contribution

The study demonstrates a novel CeO2-based thermal switch with significantly improved on/off ratio and switching width compared to previous devices.

Findings

Achieved an on/off b5appa-ratio of 5.8.

Demonstrated 100-cycle durability with stable b5appa values.

Potential for use in thermal shutters and displays.

Abstract

Thermal switches, which electrically turn heat flow on and off, have attracted attention as thermal management devices. Electrochemical reduction/oxidation switches the thermal conductivity (\k{appa}\) of active metal oxide films. The performance of the previously proposed electrochemical thermal switches is low; on/off \k{appa}\-ratio is mostly less than 5 and \k{appa}\-switching width is less than 5 W/mK. We used CeO2 thin film as the active layer deposited on a solid electrolyte YSZ substrate. When the CeO2 thin film was reduced once (off-state) and then oxidized (on-state), \k{appa}\ was about 2.2 W/mK in the most reduced state, and \k{appa}\ increased with oxidation to 12.5 W/mK (on-state). This reduction (off-state)/oxidation (on-state) cycle was repeated 100 times and the average value of \k{appa}\ was 2.2 W/mK after reduction (off-state) and 12.5 W/mK after oxidation (on-state). The on/off \k{appa}\-ratio was 5.8 and \k{appa}\-switching width was 10.3 W/mK. The CeO2-based solid-state electrochemical thermal switches would be potential devices for thermal shutters and thermal displays.