Aluminum as promising electrode for Mg2(Si,Sn)-based thermoelectric devices

The solid solutions of magnesium silicide and magnesium stannide Mg2(Si,Sn) are high-performance thermoelectric (TE) materials with the advantage of being composed of light, cheap, and abundant elements. Therefore, they are especially attractive for the conversion of remnant heat into electricity in fields like the automotive sector or the aerospace industry. The optimization of Mg2(Si,Sn)-based thermoelectric generators requires establishing a suitable electrode to ensure unhindered conduction of the electrical current through the module. We have tested aluminum for such applications and developed a technological process for joining. The obtained functionalized TE legs showed electrical contact resistances below 10 μΩcm2 for both p- and n-type materials and the values are preserved or even lowered with annealing. The p-type material is found to be stable and in the n-type, there is no indication for a charge carrier compensation due to the electrode, as was previously reported e.g. for Cu and Ag. Comparison with other reported electrodes shows that aluminum is so far the most suitable electrode for an Mg2(Si,Sn)-based module.