Methods of 3D Printing Bi₂Te₃-Ink-Based Thermoelectric Modules

The development of additive manufacturing methods for producing sustainable energy sources can enable their more widespread use, especially in large-area or custom-form-factor applications. Bismuth telluride (BiTe)-based thermoelectric modules have attracted considerable interest as sustainable energy sources owing to their proficient ability to convert waste heat into electrical energy. However, traditional methods of manufacturing BiTe-based thermoelectric modules restrict their geometry to small, planar, and rigid devices. Recently, Kim, <i>et al.</i> [1] has established a method of 3D printing all-inorganic n- and p-type BiTe inks resulting in thermoelectric properties comparable to bulk. However, these inks require 450°C post-print annealing, where the films adhere to ceramic or metal substrates as they undergo significant shrinking, limiting compatible substrate materials to planar graphite surfaces. In this work, we explore methods of 3D syringe printing, sintering, and metallizing printed BiTe structures for producing, custom-form, large-area, and/or flexible thermoelectric modules. In the sintering of BiTe inks, it is found that spray-on graphite lubricant can be used to precoat ceramic or metal substrates, acting as a non-stick release layer for the ink as it anneals. Additionally, silicone, a printable material, is found to be compatible with BiTe during the annealing process, allowing for the making of additively manufactured silicone preforms which BiTe inks can be injected into before cofiring. Finally, it is found that aerosol jet printed and laser-sintered gold nanoparticle ink stably metallizes printed BiTe structures with low-contact resistance. Future work will focus on demonstrating large-area, gold-metallized thermoelectric modules produced from BiTe inks cofired in a silicone preform. Additionally, flexible thermoelectric modules will be explored using polydimethylsiloxane (PDMS) encasing of cofired BiTe-silicone preforms. Overall, this work establishes an expanded set of methods to 3D print, sinter, and metallize BiTe inks for producing custom-form, large-area, and/or flexible energy harvesting devices. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.<br/><br/>[1] Kim, Fredrick, et al. 3D Printing of Shape-Conformable Thermoelectric Materials using All-Inorganic Bi₂Te₃-Based Inks. Nature Energy 3, 301-309, 2018.