Time-Enhanced Performance of Oxide Thermoelectric Modules Based on a Hybrid p-n Junction

Nikola Kanas; Rasmus Bjørk; Kristin Høydalsvik Wells; Raphael Schuler; Mari-Ann Einarsrud; Nini Pryds; Kjell Wiik

doi:10.1021/acsomega.0c04134

Time-Enhanced Performance of Oxide Thermoelectric Modules Based on a Hybrid p-n Junction

ACS Omega. 2020 Dec 28;6(1):197-205. doi: 10.1021/acsomega.0c04134. eCollection 2021 Jan 12.

Authors

Nikola Kanas^{1

2}, Rasmus Bjørk², Kristin Høydalsvik Wells¹, Raphael Schuler³, Mari-Ann Einarsrud¹, Nini Pryds², Kjell Wiik¹

Affiliations

¹ Department of Materials Science and Engineering, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway.
² Department of Energy Conversion and Storage, Technical University of Denmark, 2800 Kongens Lyngby, Denmark.
³ Department of Chemistry, University of Oslo, FERMiO, 0349 Oslo, Norway.

Abstract

The present challenge with all-oxide thermoelectric modules is their poor durability at high temperatures caused by the instability of the metal-oxide interfaces at the hot side. This work explains a new module concept based on a hybrid p-n junction, fabricated in one step by spark plasma co-sintering of Ca₃Co_4-x O_9+δ (CCO, p-type) and CaMnO_3-δ/CaMn₂O₄ (CMO, n-type). Different module (unicouple) designs were studied to obtain a thorough understanding of the role of the in situ formed hybrid p-n junction of Ca₃CoMnO₆ (CCMO, p-type) and Co-oxide rich phases (p-type) at the p-n junction (>700 °C) in the module performance. A time-enhanced performance of the modules attributed to this p-n junction formation was observed due to the unique electrical properties of the hybrid p-n junction being sufficiently conductive at high temperatures (>700 °C) and nonconductive at moderate and low temperatures. The alteration of module design resulted in a variation of the power density from 12.4 (3.1) to 28.9 mW/cm² (7.2 mW) at ΔT ∼ 650 °C after 2 days of isothermal hold (900 °C hot side). This new concept provides a facile method for the fabrication of easily processable, cheap, and high-performance high-temperature modules.