Study on improving comprehensive property of Te-based thermoelectric joint

Abstract

Elemental Te exhibits great future application for promising thermoelectric performance, the critical factor to extensively application is manufacturing thermoelectric joint with excellent comprehensive performance, where both material and interface optimization are necessary. The zT of Sb-doped Te was enhanced to 0.95 at 600 K for thermoelectric material Te0.985Sb0.015. Then, Ni was introduced into the interface of Te-based thermoelectric joint as a barrier layer to restrain the excessive reaction and diffusion of interface elements. The Te0.985Sb0.015/Ni/Al exhibited homogeneous interfacial microstructure and lower contact resistance< 10 μΩ cm2. After annealing at 600 K for several days, AlNi3 enriched at the Al/Ni interface and diffused to the Al matrix in the way of corroding grain boundary with the increase of holding time, which caused a huge damage to the joint structure. Whereas, when Al was replaced with Cu, the interface microstructure showed a better thermal stability at 600 K, which provides excellent interface quality and ensures stable property in service. After annealing at 600 K for 30 days, the contact resistance of Te0.985Sb0.015/Ni/Cu joint remained at 16.92 μΩ cm2 and the output power further proved the satisfactory stability of comprehensive property.