A Device-to-Material Strategy Guiding the "Double-High" Thermoelectric Module

Thermoelectric devices having both high conversion efficiency and high power density ("double-high") are in high demand for power-generation applications. Conventional research approaches on thermoelectric devices primarily focus on the realization of high conversion efficiency, while the power density is often overlooked. We propose a device-to-material design strategy for "double-high" thermoelectric modules, which integrates multiple criteria including matching thermal conductivities in p- and n-type thermoelectric materials, optimizing topologic structures of modules, and minimizing interfacial resistance. According to the thermal-conductivity matching criterion, the n-type Zr0.5Hf0.5NiSn0.97Sb0.03 half-Heusler alloy, which possesses an excellent power factor but slightly lower zT, is adopted as the partner of the p-type Nb0.86Hf0.14FeSb alloy for realizing a double-high thermoelectric module. The newly developed 8-pair module achieves a maximum conversion efficiency of 10.5% and power density of 3.1 Wcm(-2) at a temperature difference of 680 K, simultaneously breaking both records in a single-stage module.