Improvement of the conversion efficiency of Mg3Sb2 thermoelectric devices through optimizing the resistivity of the MgSbNi barrier layer

Mg3Sb2-based thermoelectric materials have been the focus of widespread investigations as promising candidates for the harvesting of waste heat. Interface stability and service performance are key points for the commercial applications of these materials. We utilized Mg4.3Sb3Ni as a barrier layer to improve the thermal stability of Mg3Sb2-based devices. However, its intrinsic high resistivity contributed negatively to the desired performance of the device. In this work, we investigated two other Mg-Sb-Ni ternary phases, MgSbNi and MgSbNi2, as new barrier layer materials to connect with Mg3.2Sb2Y0.05. The results show that the efficiency of the Mg1.2SbNi/Mg3.2Sb2Y0.05/Mg1.2SbNi joint is increased by 33% relative to the higher Mg-content barriers due to lower resistivity. The system exhibited good interfacial compatibility and showed little change with aging at 673 K for 20 days.