An electrochemical thermal transistor

TL;DR

This paper demonstrates a switchable thermal transistor using reversible electrochemical lithium intercalation in MoS2, enabling active heat flow regulation at the nanoscale with potential applications in thermal management and energy harvesting.

Contribution

It introduces a novel electrochemical thermal transistor based on lithium intercalation in MoS2, with detailed thermal and structural characterization and insights into the underlying phonon scattering mechanisms.

Findings

Achieved an order of magnitude thermal on/off ratio.

Mapped lithium ion distribution during operation.

Linked thermal conductance changes to phonon scattering mechanisms.

Abstract

The ability to actively regulate heat flow at the nanoscale could be a game changer for applications in thermal management and energy harvesting. Such a breakthrough could also enable the control of heat flow using thermal circuits, in a manner analogous to electronic circuits. Here we demonstrate switchable thermal transistors with an order of magnitude thermal on/off ratio, based on reversible electrochemical lithium intercalation in MoS2 thin films. We use spatially-resolved time-domain thermoreflectance to map the lithium ion distribution during device operation, and atomic force microscopy to show that the lithiated state correlates with increased thickness and surface roughness. First principles calculations reveal that the thermal conductance modulation is due to phonon scattering by lithium rattler modes, c-axis strain, and stacking disorder. This study lays the foundation for electrochemically-driven nanoscale thermal regulators, and establishes thermal metrology as a useful probe of spatio-temporal intercalant dynamics in nanomaterials.