Radioisotope power systems (RPSs) including thermoelectric systems are proven technologies for long-term power generation in distant, dark, and/or dusty environments where solar power is not viable. Despite significant advancements in thermoelectric (TE) material technology, modern TE systems rely on legacy TE technologies due to shortcomings in systems-integration and reliability of improved TE materials. Crucial TE material development challenges stem from the interface joining TE materials and the metallic interconnect (IC) material near the heater unit hot-end, which must be manufacturable, robust, and stable after decades of operation. In this program, QuesTek Innovations will leverage its Integrated Computational Materials Engineering (ICME) expertise and Materials by Design® technology to rapidly design and prototype a TE-IC junction combining a novel IC alloy design and a mechanically robust, highly efficient p-type PbTe material with improved power generation efficiency near radioisotope heater unit hot-end temperatures. Phase I involves thermodynamic database development and utilization of CALPHAD (CALculation of Phase Diagrams) methods to computationally design a junction between the PbTe material and a QuesTek-designed Co-based IC material with minimal experimental validation. Design will focus on thermodynamic interface stability and well-matched coefficients of thermal expansion between TE/IC materials to minimize thermal stress during fabrication and long-term operation. The database framework will be extended in Phase II work to design a similarly compatible IC-TE material junction for an improved n-type PbTe material, leading to further improved RPS efficiency. The longevity of a full device incorporating QuesTek’s novel IC alloy and improved p- and n-type PbTe materials will be simulated using CALPHAD-based diffusion simulations to capture performance over multiple decades and experimentally verified through long-term device stability tests.

Improved RPS components for improved power generation on unmanned scientific missions Exploration of deeper, darker space at the edges of our solar system Exploration of planetary moons and planetary surfaces Better opportunity to consider unmanned remote space stations Better opportunity to consider unmanned remote planet mineral mining

Improved RPS components for improved power generation to support commercial space endeavors Power to support unmanned mining operations Power to support equipment in commercial space stations and planetary bases Improved thermoelectric materials for renewable terrestrial energy harvesting