Nanocomposites based on polymers for thermoelectric applications

Thermoelectric systems are very effective in harvesting electricity from waste heat or heat sources with low temperature gradients relative to the environmental temperature. Low temperature gradients are inadequate for power generation using conventional systems but are often present in the environment (e.g., solar and geothermal energy) or generated from various power generating or consuming systems.

Consequently thermoelectric materials have attracted intense research effort toward improving thermoelectric efficiency. Despite significant efforts, there has been only marginal improvement in thermoelectric efficiency since the discovery of bismuth telluride alloys in 1960s. Typical thermoelectric semiconductor materials are expensive and relatively difficult to process, impeding their widespread use for energy conversion.

In this regard, polymer nanocomposites are very attractive as they are light and generally require relatively simple manufacturing processes compared to semiconductor based thermoelectrics. The poor thermal conductivity intrinsic to typical polymers appears ideal for thermoelectrics due to the definition of the thermoelectric figure of merit (ZT), which is a measure of thermoelectric energy conversion efficiency. Nevertheless, low electrical conductivity

has excluded polymers as feasible candidates in the past decades. With the addition of electrically conductive particles such as carbon nanotubes, the electrical conductivity of polymers can be brought into degenerate-semiconductor or metallic regimes. This conversion can be accomplished with a relatively low concentration of nanoparticles when a co-continuous percolated network is formed by them. Synthesizing composites is indeed considered as an effective strategy to achieve improved material performances by combining the

advantages of each component. Synergistic enhancement effects can be obtained by this way.

On this project we focus our work on the elaboration of composites materials based on conductor polymers or block copolymers which are able to disperse by tailored interactions the nanoparticules. Consequently thermoelectric nanocomposites are obtained and then studied as regard to the physical and thermal properties for optimization.

Subsidized projects ANR Nano-innov Thermo-innov

Contact point : Guillaume Fleury