Fabrication and testing of ceramic thermoelectric multi-leg module for high-temperature energy conversion

This study investigates the fabrication and performance of ceramic-based thermoelectric modules for high-temperature energy conversion, based on Ca 2.93 Sr 0.07 Co 4 O 9 and Ca 0.91 Y 0.03 La 0.03 Yb 0.03 MnO 3 p- and n-type materials. The p-type materials were prepared through attrition milling and classical sintering, while ball milling and hot uniaxial pressing were used for the n-type legs. The power factor reached 0.62 mW/(K 2 m) for the p-type and 0.33 mW/(K 2 m) for the n-type materials at 800 °C, being comparable to some of the best-reported values in literature. The lower thermal conductivity of n-type material (1.24 W/K/m) compared to the p-type material (1.56 W/K/m) resulted in similar ZT values for n-type (0.29) and p-type (0.43). The thermal expansion behaviour of the materials was also evaluated, demonstrating good thermal compatibility between the p- and n-type legs. The module's performance was tested at hot-side temperatures up to 900 °C, yielding a power density of 34 W/m 2 . Moreover, the module demonstrated an energy conversion efficiency of 0.8% (actual) and 6% (theoretical), thereby underscoring the practical potential of these materials. Additionally, the module exhibited excellent long-term thermal stability, maintaining its performance after 2000 h of exposure at 900 °C and after undergoing 100 thermal cycles, demonstrating its suitability for high-temperature energy recovery applications. • Fabricated high-performance ceramic thermoelectric (TE) modules for high-temperature applications. • Achieved power factors of 0.62 mW/(K²m) (p-type) and 0.33 mW/(K²m) (n-type) at 800°C. • The n-type material's lower thermal conductivity (1.24 W/K/m) compared to the p-type one (1.56 W/K/m) resulted in nearly identical ZT values for the n-type (0.29) and p-type (0.43) materials. • Demonstrated excellent thermal expansion compatibility between TE legs for structural stability. • Energy conversion efficiency reached 0.8% (actual) and 6% (theoretical), comparable with commercial intermetallic modules at moderate temperatures (~550 °C), emphasizing the potential for practical applications. • Module showed long-term stability, retaining performance after 2000 hours at 900°C and 100 thermal cycles. • Results highlight the potential of oxide-based TE modules for efficient energy recovery in extreme environments.