Segmented Thermoelectric Oxide-Based Module for High-Temperature Waste Heat Harvesting

We report a high-performance thermoelectric (TE) oxide-based module using the segmentation of half-Heusler Ti_0.3Zr_0.35Hf_0.35CoSb_0.8Sn_0.2 and misfit-layered cobaltite Ca₃Co₄O_9+δ as the p-leg and 2% Al-doped ZnO as the n-leg. The maximum output power of a 4-couple segmented module at ΔT=700 K attains a value of approximately 6.5 kWm^-2, which is three times higher than that of the best reported non-segmented oxide module. The TE properties of individual legs, as well as the interfacial contact resistances, were characterized as a function of temperature. Numerical modeling was used to predict the efficiency and to evaluate the influence of the electrical and thermal losses on the performance of TE modules. Initial long-term stability tests of the module at the hot and the cold side temperatures of 1073 K and 444 K, respectively, showed a promising result with 4% degradation for 48 h operating in air.