Enhanced thermoelectric properties in Cu12Sb4S13 tetrahedrite by incorporation of carbon-based nanoparticles

The high thermal conductivity of bulk thermoelectric (TE) materials is the main reason limiting the application field of bulk TE devices. The tetrahedrite (Cu₁₂Sb₄S₁₃) is a kind of TE material with extremely low thermal conductivity. If the thermal conductivity can be further reduced, it is expected to expand the application field of bulk TE devices. Herein, some carbon-based nanoparticles (diamond, CNTs, B₄C, and SiC) of different grain size are embedded into the Cu_11.5Ni_0.5Sb₄S_12.7 (CNSS) matrix by mechanical alloying and spark plasma sintering to enhance the TE performance. It is discovered that the Seebeck coefficient of CNSS/carbon-based nanoparticles nanocomposites remarkably increased while the total thermal conductivity significantly decreased because of the nanopores and new heterogeneous interface of CNSS/carbon-based nanoparticles induced by nanoscale carbon-based particles enhancing carrier and phonon scattering. As a result, the total thermal conductivity of the nanocomposites decreases from 1.36 Wm^-1 K⁻¹ to 0.93 W m⁻¹ K⁻¹ at 723 K with 0.2 vol% of SiC nanoparticles, decreasing 32 %. The maximum ZT reaches 1.0 at 723 K for the nanocomposite with 0.20 vol% of SiC, increasing 43 %. These results verify that the introduction of carbon-based nanoparticles is a promising method to improve the application of Cu₁₂Sb₄S₁₃-based modules.