Thermoelectric Cu-doped (Bi,Sb)2Te3: Performance enhancement and stability against high electric current pulse

P-type Bi2-xSbxTe3 is one of the most mature and widely used thermoelectric (TE) materials. Enhancing its performance is important and has generated significant research attention, with studies ranging from chemical doping to various fabrication processes. In this work, we applied a method combining mechanical alloying and spark plasma sintering to synthesize Cu-doped Bi0.3Sb1.7Te3. By adjusting the doping amount of Cu, the electrical conductivity and power factor were improved with a reduced lattice thermal conductivity, leading to a high dimensionless figure of merit (ZT) up to 1.32 at 400 K. This high performance could be maintained even after the sintered sample was subjected to a 100 A electric current pulse (ECP) at 523 K for 30 min, despite some slight changes in the electrical transport properties. Interestingly, it was found that the ECP treatment induced grain refinement and nanoscale inhomogeneity that reduced the lattice thermal conductivity, which canceled the negative effect on the ZT that had been caused by the slight decline in power factor. This work validated the effectiveness of Cu-doping for Bi2-xSbxTe3, and it also demonstrated a facile method for the stability study of thermoelectric materials.