ICT2014 Abstracts

Commonly used thermoelectric generators (TEG) exhibit an in-plane configuration of alternating rigid ceramic modules, consisting of n-type and p-type thermoelectric materials. Therefore, the connection of heat exchange devices to the TEG is often complicated when designing a thermoelectric module. In our work, we describe a novel TEG with a high degree of design freedom. By using flexible ceramic polymer hybrid materials, the shape of the TEG is determined only by the processability of the polymer and thus the link to the complete thermoelectric system is enormously variable.

A novel tubular modular TEG was developed with the purpose to use low-cost, highly flexible and highly available thermoelectric oxides. Therefore, a large variety of metal oxides were investigated with the aim to combine good thermoelectric properties with the processability of polymer materials, whereupon ceramic powders were used as fillers in a polysiloxane matrix with different filling degrees. 

The reduction of electrical contact resistances between the ceramic particles in the polymer compound was found out to be the most important issue. Concerning the n-type conducting material for the TEG, mica platelets coated with Sb-doped SnO₂ and globular particles of SnO₂ were investigated. For the p-type semiconductor, the titanium suboxide Ti₂O₃ and Cu-Delafossites (CuFeO₂) were doped with different transition metals, to find the optimum between electrical conductivity and Seebeck coefficient.

By combining the above mentioned optimization methods with a thermal after treatment in defined gas atmospheres, both the thermoelectric properties and the processability of the investigated materials could be improved, so a tubular TEG prototype with circular thermoelectric modules could have been developed. Its power output is considered high enough for energy self-sustaining sensor applications at temperatures up to 500 °C.