Outreach

Published a review on thermoelectric materials, from the very beginning and to the future!

A broad and comprehensive review on thermoelectric materials has been published in "Materials Science and Engineering: R: Reports", a monthly peer-reviewed scientific journal published by Elsevier established in 1993 with an impact factor of more than 25! The review, with 47 pages, includes the participation of Mariano Campoy-Quiles and Bernhard Dörling from the ICMAB-CSIC, and 12 more institutions around the world (Italy, USA, UK, Germany, Sweden and Spain).

icmab

29 January 2019

Figure: Evolution of zT (figure of merit to evaluate thermoelectric materials performance) for p-type (c) and n-type (d) chalcogenides, silicides, skutterudites, Zintls, clathrates, Heusler, oxides, organic and composites.Source: the article.

The review, entitled "Thermoelectrics: From history, a window to the future", reviews the broad field of thermoelectrics, from its very origins and to the future.

Progress in thermoelectrics and milestones that led to the current state-of-the-art are presented by adopting an historical footprint. The review begins with an historical excursus on the major steps in the history of thermoelectrics, from the very early discovery to present technology.

A panel on the theory of thermoelectric transport in the solid state reviews the transport theory in complex crystal structures and nanostructured materials.

Then, the most promising thermoelectric material classes are discussed one by one in dedicated sections and subsections, carefully highlighting the technological solutions on materials growth that have represented a turning point in the research on thermoelectrics.

Finally, perspectives and the future of the technology are discussed in the framework of sustainability and environmental compatibility.

What is thermoelectricity?

Thermoelectricity offers a sustainable path to recover and convert waste heat into readily available electric energy, and has been studied for more than two centuries.

Origins

From the controversy between Galvani and Volta on the Animal Electricity, dating back to the end of the XVIII century and anticipating Seebeck’s observations, the understanding of the physical mechanisms evolved along with the development of the technology.

In the XIX century Ørsted clarified some of the earliest observations of the thermoelectric phenomenon and proposed the first thermoelectric pile, while it was only after the studies on thermodynamics by Thomson, and Rayleigh’s suggestion to exploit the Seebeck effect for power generation, that a diverse set of thermoelectric generators was developed.

From such pioneering endeavors, technology evolved from massive, and sometimes unreliable, thermopiles to very reliable devices for sophisticated niche applications in the XX century, when Radioisotope Thermoelectric Generators for space missions and nuclear batteries for cardiac pacemakers were introduced.

Nanostructuration of the materials

While some of the materials adopted to realize the first thermoelectric generators are still investigated nowadays, novel concepts and improved understanding of materials growth, processing, and characterization developed during the last 30 years have provided new avenues for the enhancement of the thermoelectric conversion efficiency, for example through nanostructuration, and favored the development of new classes of thermoelectric materials.

Abundant, non-toxic materials and large scale applications

With increasing demand for sustainable energy conversion technologies, the latter aspect has become crucial for developing thermoelectrics based on abundant and non-toxic materials, which can be processed at economically viable scales, tailored for different ranges of temperature. This includes high temperature applications where a substantial amount of waste energy can be retrieved, as well as room temperature applications where small and local temperature differences offer the possibility of energy scavenging, as in micro harvesters meant for distributed electronics such as sensor networks.

While large scale applications have yet to make it to the market, the richness of available and emerging thermoelectric technologies presents a scenario where thermoelectrics is poised to contribute to a future of sustainable future energy harvesting and management.

Reference Article:

Thermoelectrics: From history, a window to the future
Davide Beretta, Neophytos Neophytou, James M.Hodges, Mercouri G. Kanatzidis, DarioNarducci, Marisol Martin-Gonzalez, Matt Beekman, Benjamin Balke, Giacomo Cerretti, Wolfgang Tremel, Alexandra Zevalkink, Anna I. Hofmann, Christian Müller, Bernhard Dörling, Mariano Campoy-Quiles, Mario Caironi.
Materials Science and Engineering: R: Reports. DOI:10.1016/j.mser.2018.09.001

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