High Power Density Thermoelectric Generators with Skutterudites

Thermoelectric generators (TEGs) offer a versatile solution to convert low-grade heat into useful electrical power. While reducing the length of the active thermoelectric legs provides an efficient strategy to increase the maximum output power density pmax, both the high electrical contact resistances and thermomechanical stresses are two central issues that have so far prevented a strong reduction in the volume of thermoelectric materials integrated. Here, it is demonstrated that these barriers can be lifted by using a nonconventional architecture of the legs which involves inserting thick metallic layers. Using skutterudites as a proof-of-principle, several single-couple and multi-couple TEGs with skutterudite layers of only 1 mm are fabricated, yielding record pmax ranging from 3.4 up to 7.6 W cm−2 under temperature differences varying between 450 and 630 K. The highest pmax achieved corresponds to a 60-fold increase per unit volume of skutterudites compared to 1 cm long legs. This work establishes thick metallic layers as a robust strategy through which high power density TEGs may be developed.