Enhanced thermoelectric performance of Cu12Sb4S13−δ tetrahedrite via nickel doping

Cu 12 Sb 4 S 13 tetrahedrite has received great attention as an earth-abundant and environmental-friendly thermoelectric material. This work aims to uncover the thermoelectric performance-enhancing effect and the mechanism of nickel doping on tetrahedrite. A series of Cu 12− x Ni x Sb 4 S 13− δ ( x = 0.5, 0.7, 1.0, 1.5 and 2.0) compounds were synthesized by mechanical alloying combined with spark plasma sintering. It is found that the thermal conductivity sharply reduces with increasing Ni content over the entire temperature range, < 0.9 W m −1 K −1 , accompanied with an enhanced thermoelectric power factor. The model predicted that the reduced lattice thermal conductivity is attributed to mid-frequency phonon scattering, caused by precipitates and dislocations resulting from Ni doping. Consequently, a high ZT value up to 0.95 at 723 K was achieved for Cu 11 NiSb 4 S 13− δ , corresponding to a ∼46% increase over non-doped Cu 12 Sb 4 S 13− δ . Furthermore, the cyclic measurement showed that the Ni-doped tetrahedrites displayed high chemical stability.