Co-Fired Multilayer Thermoelectric Generators Based on Textured Calcium Cobaltite

Thermoelectric generators are very attractive devices for waste heat energy harvesting as they transform a temperature difference into electrical power. However, commercially available generators show poor power density and limited operation temperatures. Research focuses on high-temperature materials and innovative generator designs. Finding the optimal design for a given material system is challenging. Here, a theoretical framework is provided that allows appropriate generator design selection based on the particular material properties. For high-temperature thermoelectric oxides, it can be clearly deduced that unileg multilayer generators have the highest potential for effective energy harvesting. Based on these considerations, prototype unileg multilayer generators from the currently best thermoelectric oxide Ca3Co4O9 are manufactured for the first time by industrially established ceramic multilayer technology. These generators exhibit a power density of 2.2 mW cm-2 at a temperature difference of 260 K, matching simulated values and confirming the suitability of the technology. Further design improvements increase the power density by a factor of 22 to facilitate practicable power output at temperature differences as low as 7 K. This work demonstrates that reasonable energy harvesting at elevated temperatures is possible with oxide materials and appropriate multilayer design. This work presents a theoretical framework and experimental proof to maximize the power density of thermoelectric generators for energy harvesting by purposeful design selection. Consequently, unileg multilayer generators are manufactured from the currently best thermoelectric oxide Ca3Co4O9 for the first time. Design improvements to increase power density by a factor of 22 are discussed, emphasizing the potential of multilayer technology for thermoelectric energy harvesting.image