Decoupling Thermoelectric Performance and Stability in Liquid-Like Thermoelectric Materials

Area of Science:

• Materials Science
• Solid-State Physics
• Energy Conversion

Background:

• Liquid-like materials offer high thermoelectric figure of merit (zT), low cost, and environmental benefits.
• Practical application is hindered by poor service stability due to metal deposition issues under thermal and electrical stress.
• High efficiency (zT) and stability (critical voltage) are often inversely correlated in these materials.

Purpose of the Study:

• To decouple the correlation between thermoelectric efficiency and material stability in liquid-like materials.
• To enhance both zT and critical voltage simultaneously for practical thermoelectric applications.
• To demonstrate a strategy for improving the stability and performance of Cu2-xS based thermoelectrics.

Main Methods:

• Thermodynamic analysis to understand the correlation between zT and critical voltage.
• Doping immobile ions (Fe) into the liquid-like sublattice of Cu2-xS.
• Characterization of thermoelectric properties, including zT and critical voltage, at elevated temperatures (1000 K).

Main Results:

• Doping immobile Fe ions into Cu1.90S minimally impacted the critical voltage.
• Fe doping significantly boosted the zT to 1.5 at 1000 K by optimizing carrier concentration.
• The Fe-doped Cu2-xS compounds demonstrated potential for widespread civil applications.

Conclusions:

• Immobile ion doping is an effective strategy to decouple and improve both stability and efficiency in liquid-like thermoelectrics.
• Fe-doped Cu2-xS represents a promising material for stable, high-performance thermoelectric devices.
• This approach can be extended to other liquid-like thermoelectric materials, broadening their applicability.