Minimizing Thermal Conductivity For Boosting Thermoelectric Properties Of Cu-Ni-Based Alloys Through All-Scale Hierarchical Architectures

Constantan (Cu-Ni alloy) is widely used in the field of thermocouples due to its excellent thermoelectric and mechanical properties. To broaden the application area, the intrinsically high thermal conductivity is intentionally suppressed with the aim to increase the thermoelectric figure-of-merit (ZT) and eventually the energy conversion efficiency. All-scale hierarchical architectures including the point defect, second phase, nanocomposite, and micropore are realized in Cu-Ni-based alloys, leading to the significant reduction in thermal conductivity from 18.14 to 3.23 W m(-1) K-1 at 773 K. Therefore, the thermoelectric properties have been improved with the ZT being up to 0.23 at 773 K. The present work demonstrates a promising and general strategy to enhance the thermoelectric performance of materials with ultrahigh electrical and thermal conductivity.