P-type HIgh Manganese Silicides by design for high performance and sustainable thermoelectric materials – PHIMS

The traditional technologies of power generation, process industries (metallurgy, glass, chemicals) and transport are responsible of an enormous amount of waste heat dissipated into the environment (estimated at 520 Mtoe, Million Tons of Oil Equivalent, in Europe). Generating electricity from waste heat by means of “green” thermoelectric generators will reduce the global CO2 footprint of these activities. Nanostructured thermoelectric materials overcome the poor conversion efficiency of earlier bulk materials but the remaining hurdles to the uptake of a competitive industrial energy harvesting technology are the technology cost, the abundance and the toxicity of the constituting materials.

The PHIMS project aims the development of efficient thermoelectric nanomaterials (ZT=1.5), compatible with industrialization in large volume (low cost production processes, abundant materials) and the rules of Hygiene, Health and Environment (HSE). The innovative materials targeted will fill the gap for p-type high performance nanostructured materials to address high Carnot efficiency intermediate temperature range applications, from 500K to 800K. Achieving thermoelectrics with energy conversion figure of merit (ZT) of 1.5 leads to a conversion efficiency close to 20% in the targeted temperature range, competing with current renewable energy sources (solar, wind and geothermal). The availability of p-type materials responding to similar specifications than state-of-the-art n-type Mg2SiSn nanostructured alloys will bring the following competitive advantages : increase the technology performance for medium temperature range applications (matching of p and n type legs figure of merit), decrease the technology cost (substitution of available p-type SiGe alloys by low cost and abundant base elements) while requiring no increase of manufacturing complexity (Si based alloys). Such development of material performance (figure of merit ZT value) and material cost can lead to disruptive technologies and potentially impact commercialisation. The resulting heterogeneous thermoelectric generators manufactured inside PHIMS will be particularly adapted to the naval applications addressed by the PHIMS industrial manufacturer of thermoelectric generators: Hotblock OnBoard.

PHIMS will focus on p-type polycrystalline solid solutions of Cr-Mn-Si and Cr-Ge-Mn-Si families having as characteristics:
- a nanostructured architecture consisting of nano-precipitates dispersed into a solid-solution alloy, allowing the phonon scattering at interfaces responsible for lattice thermal conductivity reduction and therefore thermoelectric figure of merit (ZT) increase ;
- eco-friendly constituting elements, abundant and inexpensive (which will significantly reduce the material cost of the technology), but also non-toxic, (which will increase the acceptability of technology under HSE rules, as compared to state of the art materials).

The PHIMS consortium gathers the partners required to address the scientific and technological challenges that will pave the way to industrialization: two upstream partners (ICMCB, ICG), a technology integration center (CEA / Liten), a SME whose mission is to bring to the market thermoelectric enabled competitive energy recovery systems (Hotblock OnBoard).