Multiscale architectures boosting thermoelectric performance of copper sulfide compound

Area of Science:

• Materials Science
• Nanotechnology
• Thermoelectrics

Background:

• Copper sulfide (Cu_2-S) is a promising medium-temperature thermoelectric material due to its high performance and earth abundance.
• Tuning electrical transport and phonon scattering in Cu_2-S is crucial for improving its thermoelectric properties, leveraging its unique liquid-like copper ion behavior.

Purpose of the Study:

• To fabricate multiscale architecture-engineered Cu_2-S.
• To investigate the impact of nanostructure and grain-boundary engineering on the thermoelectric properties of Cu_2-S.
• To achieve enhanced thermoelectric performance in copper sulfide materials.

Main Methods:

• Room-temperature wet chemical synthesis combined with mechanical mixing and spark plasma sintering.
• Fabrication of multiscale architecture-engineered Cu_2-S.
• Characterization of electrical conductivity, lattice thermal conductivity, and figure of merit (zT).

Main Results:

• Electrical conductivity was enhanced by four times at 800 K compared to conventional Cu_2-S, attributed to a potential energy filtering effect at new grain boundaries.
• Reduced lattice thermal conductivity of 0.2 W·m^-1·K^-1 was achieved due to increased phonon scattering from the multiscale architecture.
• A figure of merit (zT) of 1.0 was obtained at 800 K, a record value for chemically synthesized copper sulfide.

Conclusions:

• Multiscale architecture engineering and the introduction of nanostructures are effective strategies for enhancing the thermoelectric properties of copper sulfide.
• The formation of new interfaces plays a significant role in improving thermoelectric performance.
• This study demonstrates a viable pathway for developing high-performance thermoelectric materials based on earth-abundant elements.