Structure Optimization and Multi-frequency Phonon Scattering Boosting Thermoelectrics in Self-Doped CoSb₃-Based...

Area of Science:

• Materials Science
• Energy Conversion
• Solid State Physics

Background:

• Thermoelectric devices offer a promising route for waste heat recovery, crucial for energy sustainability.
• Cobalt antimonide (CoSb3)-based skutterudites exhibit excellent thermal stability, making them suitable for device integration.
• However, pristine CoSb3 materials suffer from high thermal conductivity and low Seebeck coefficients, limiting their thermoelectric performance.

Purpose of the Study:

• To enhance the thermoelectric properties of CoSb3-based materials.
• To simultaneously improve structural characteristics and phonon scattering.
• To optimize electrical and thermal transport for higher efficiency.

Main Methods:

• Synthesizing In-filled CoSb3 coordinated with excessive Sb.
• Investigating structural modifications and phonon interactions.
• Analyzing electrical properties (Seebeck coefficient, carrier concentration) and thermal conductivity.

Main Results:

• Achieved simultaneous structural improvement and enhanced phonon interaction in In-filled CoSb3.
• Excess Sb compensated Sb4 ring deficiency, improving the Seebeck coefficient and carrier concentration.
• Reduced lattice thermal conductivity through InSb nanoparticles, In/Sb-alloying, and In atom vibrations.
• Obtained a peak figure of merit (zTmax) of ~1.27 at 650 K and an average zTavg of ~0.9 from 300-750 K in In1.4Co4Sb12 + 8%Sb.

Conclusions:

• In-filling and excess Sb effectively optimize the thermoelectric performance of CoSb3-based materials.
• The synergistic effects enhance both electrical conductivity and reduce thermal conductivity.
• This study provides a valuable strategy for designing high-performance thermoelectric materials for waste heat recovery.