Stabilization of Superionic Copper Selenide Based Thermoelectric Materials

Abstract

Thermoelectric (TE) technology enables the direct conversion between heat and electricity, thereby contributing to the alleviation of the prevailing energy crisis and the mitigation of environmental concerns. Bismuth telluride-based TE materials have been commercially utilized, while they are mainly applied to solid-state cooling rather than energy harvesting. Superionic conductors including copper chalcogenides and silver chalcogenides are rendered as promising TE candidates for power generation due to their superior thermoelectric figure of merit (ZT) at middle or high temperatures; the liquid-like behavior of ions aligns these systems with the concept of phonon-liquid electron-crystal (PLEC). Although the mobile ions are beneficial to enhancing the electrical transport and phonon scattering, their directional migration driven by an electric field or temperature gradient can result in the unintended deposition of metals, which can impair both the TE properties and the service stability of the materials. Therefore, it is imperative to identify stabilized liquid-like TE materials that can withstand current strike and high temperature.