Utilizing novel enhancement principles to develop high performance thermoelectrics

Abstract

Development of thermoelectric (TE) materials is important, for energy saving via waste heat power generation [1], and IoT power sources [2]. For high TE performance, tradeoffs must be overcome, between Seebeck coefficient S and electrical conductivity s, and between electrical and thermal conductivity k [3].

For the latter, in addition to nanostructurings, intrinsic low k mechanisms: Materials informatics approach [4], doping leading to lattice softening [5], heterogeneous bonding from mixed anions [6], etc. For the first tradeoff, magnetism can be utilized to enhance S via magnon drag in CuFeS2 [7] and metastable Fe2VAl-based thin films [8,9], paramagnon drag in CuGaTe2 [10], Bi2Te3 [11] etc., Spin fluctuation [12], Spin entropy [13].

Recently, striking Cu doping effect in Mg3Sb2 : interstitial Cu doping lowered the phonon group velocity, while doping into the grain boundaries led to very high mobilities similar to single crystals, while being low k polycrystalline. An initial realistic 8-pair module exhibited efficiency of 7.3%@320oC, while estimated material efficiency ~11%! [14]. Tuning toward RT yielded 8-pair module with efficiency of 2.8%@100oC and cooling of 56.5 K [15]. Recently, a single element device of doped Mg3Sb2 achieved efficiency ~12% [16].

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