Progress Status Of The Development Of High-Efficiency Segmented Thermoelectric Couples

摘要

Radioisotope Thermoelectric Generators (RTGs) have been successfully used to power spacecraft for deep space missions as well as for terrestrial applications where unattended operation in remote locations is required. They have consistently demonstrated their extraordinary reliability and longevity (more than 30 years of life). NASA's Radioisotope Power Systems Technology Advancement Program is pursuing the development of more efficient thermoelectric technologies that can increase performance by a factor of 2 to 4X over state-of-practice systems that are limited to device-level efficiencies of 7.5% or less, and system-level specific power of 2.8 to 5 W/kg. Over the last few years, under the Advanced Thermoelectric Couples (ATEC) task, several advanced high-temperature thermoelectric materials, including n-type La_(3-x)Te_4~(4.6), p-type Yb_(14)MnSb_(11)~3, and n- and p-type filled skutterudites (SKD), have been developed for integration into advanced power generation devices at the Jet Propulsion Laboratory (JPL). The stability of their thermoelectric properties has been demonstrated for over 18,000 hours up to 1323 K. Stable metallization and sublimation suppression barriers/coatings have been successfully developed. JPL is now focusing on developing segmented and skutterudite only couples based on these high-temperature materials to achieve high conversion efficiencies. Recent performance tests have demonstrated 11 to 15% conversion efficiencies with cold and hot-junction temperatures in the 423-473 K and 973-1273 K range, respectively.