Conversion efficiency of skutterudite-based thermoelectric modules

Abstract

Presently, the only commercially available power generating thermoelectric (TE) modules are based on bismuth telluride (Bi2Te3) alloys and are limited to a hot side temperature of 250 °C due to the melting point of the solder interconnects and/or generally poor power generation performance above this point. For the purposes of demonstrating a TE generator or TEG with higher temperature capability, we selected skutterudite based materials to carry forward with module fabrication because these materials have adequate TE performance and are mechanically robust. We have previously reported the electrical power output for a 32 couple skutterudite TE module, a module that is type identical to ones used in a high temperature capable TEG prototype. The purpose of this previous work was to establish the expected power output of the modules as a function of varying hot and cold side temperatures. Recent upgrades to the TE module measurement system built at the Fraunhofer Institute for Physical Measurement Techniques allow for the assessment of not only the power output, as previously described, but also the thermal to electrical energy conversion efficiency. Here we report the power output and conversion efficiency of a 32 couple, high temperature skutterudite module at varying applied loading pressures and with different interface materials between the module and the heat source and sink of the test system. We demonstrate a 7% conversion efficiency at the module level when a temperature difference of 460 °C is established. Extrapolated values indicate that 7.5% is achievable when proper thermal interfaces and loading pressures are used.

Half-Heusler Alloys for Efficient Thermoelectric Power Conversion

“…Cook et al reported 20% conversion efficiency for a 3-stage TEG that utilized HH alloys in the high temperature stage [5]. These reported TEG efficiencies are already higher than those of state-of-the-art TEGs [11][12][13][14]. The power density output of HH alloy based TEG was reported to exceed 3 W/cm 2 [3].…”

Research Update: Cu–S based synthetic minerals as efficient thermoelectric materials at medium temperatures

“…Therefore, other above-listed materials with less toxicity have recently been utilized for TE modules. [6][7][8] They are expected to be put into practical use in the near future if the cost performance is more improved.…”

High-performance n-type YbxCo4Sb12: from partially filled skutterudites towards composite thermoelectrics

“…3,4 Skutterudite antimonide is one of the most promising candidates for intermediate temperature TE power generation (500-900 K) owing to the availability of both high-performance n-and p-type compositions within this material class with excellent thermomechanical properties and relatively low-cost and abundant constituent elements (compared with the state-of-the-art Bi 2 Te 3 and PbTe). [4][5][6][7][8][9] Guest filling in the structural nanovoids to form the so-called filled skutterudites (i.e., R y (Co,Fe) 4 Sb 12 , where R represents the filler and y the filling fraction) is the best strategy for enhancing the TE figure of merit ZT as the fillers both act to control carrier concentration and significantly suppress the propagation of heat-carrying phonons. 6,7 Many elements can be partially filled in CoSb 3 , such as alkali, alkaline earth, rare earth, and group IIIA elements.…”