About this Research Topic
Waste heat harvesting has become an increasingly important contributor to sustainable energy ecosystems. Thermoelectric (TE) materials are capable of harvesting waste heat and converting it into useful electrical power or regulating temperature upon exposure to low-power direct current. TE materials are already in use in several types of systems, including the thermal regulation of computer processors, portable coolers, and cooling night-vision devices. However, the limited performance of conventional materials has been the impeding factor in their widespread adoption. As such, further work is required to carry out fundamental science and technology research for environmentally friendly, low-cost, stable, and durable TE materials and devices based on theoretical analysis and experimental research.
In the last decade, nanotechnology has made an impact in the field of TEs. Several known TE materials have shown significantly improved conversion performance when made of nanosized building blocks, due to confinement and/or scattering-based effects. The “nano” approach offers the possibility of separately decoupling and engineering the power factor and thermal conductivity. One important aspect in bulk TEs is to maintain the nano-features intact within the material during subsequent processing steps by avoiding conventional processing routes, which make use of high temperature processes for prolonged periods. In doing this, there is also a strong drive to develop more environmentally friendly TE material compositions from abundant elements.
Beyond the gap with practical applications and the search for environmentally friendly approaches, other serious issues still exist in thermoelectrics research, such as the chemical constituents being scarce or toxic, diffusion of contacting materials into TEs which degrades performance, and degradation of material upon thermal cycling due to the formation of some volatile components. The processing of TE powders into compacts has not been studied in detail, where recent research has shown a significant impact of the resultant microstructure of the compacts on the transport properties. Furthermore, the synthesis of some promising TE compositions is very energy-intensive, and this needs to be tackled with the development of a new set of synthetic protocols.
Further research efforts should be devoted to studying the transport mechanism in inorganic and hybrid materials systems, by combining theoretical and experimental results, thus revealing the intrinsic relationship and effect on TE transport properties. Through optimizing the relevant parameters, it should be possible to realize the all-round design concept of TEs from materials to devices, and develop highly effective energy harvesting devices, paving the way for their practical applications.
This Research Topic will focus on the development of TE materials for durable TE energy harvesting devices for large-scale applications, primarily industrial environments and processes where high T heat is available; however, other low-cost hybrid and flexible TE materials and device technologies are also encouraged. Articles may be original research or reviews. Topics of interest may include, but are not limited, to:
• theoretical, computational, or experimental insights into TE transport
• the development of energy- and resource-effective synthetic methods for TE materials
• the development of high-performance TE materials based on inorganics
• the development of high-performance TE materials based on polymers and ionic liquids
• the development of high-performance TE materials based on inorganic-polymer hybrids/nanocomposites
• processing inorganic TE materials (size, morphology, sintering schemes, etc.)
• optimization (contacts, diffusion) and development of inorganic TE devices for medium and high-T ranges
• the development of high-performance TE modules based on geometrical and physical improvement on heat exchangers and materials
Keywords: Nanomaterials, thermoelectric, waste heat recovery, thermoelectric module, flexible and hybrid module technologies
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