arXiv subjects

Mitsuki Yoshimura

Publications and source records attributed to Mitsuki Yoshimura.

2 recordsLinked to original sources

arXiv2024

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

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.

cond-mat.mtrl-sci↗

arXiv2024

Solid-State Electrochemical Thermal Transistors with Large Thermal Conductivity Switching Widths

Thermal transistors that switch the thermal conductivity (\k{appa}) of the active layers are attracting increasing attention as thermal management devices. For electrochemical thermal transistors, several transition metal oxides (TMOs) have been proposed as active layers. After electrochemical redox treatment, the crystal structure of the TMO is modulated, which results in the \k{appa} switching. However, the \k{appa} switching width is still small (< 4 W/mK). In this study, we demonstrate that LaNiOx-based solid-state electrochemical thermal transistors have a \k{appa} switching width of 4.3 W/mK. Fully oxidised LaNiO3 (on state) has a \k{appa} of 6.0 W/mK due to the large contribution of electron thermal conductivity (\k{appa}ele, 3.1 W/mK). In contrast, reduced LaNiO2.72 (off state) has a \k{appa} of 1.7 W/mK because the phonons are scattered by the oxygen vacancies. The LaNiOx-based electrochemical thermal transistor exhibits excellent cyclability of \k{appa} and the crystalline lattice of LaNiOx. This electrochemical thermal transistor may be a promising platform for next-generation devices such as thermal displays.

cond-mat.mtrl-sci↗