High-temperature and high-power-density nanostructured thermoelectric generator for automotive waste heat recovery

[Display omitted] •A thermoelectric generator (TEG) is fabricated using nanostructured half-Heusler materials.•The TE unicouple devices produce superior power density above 5W/cm2.•A TEG system with over 1kW power output is demonstrated by recovering automotive waste heat. Given increasing energy use as well as decreasing fossil fuel sources worldwide, it is no surprise that interest in promoting energy efficiency through waste heat recovery is also increasing. Thermoelectric generators (TEGs) are one of the most promising pathways for waste heat recovery. Despite recent thermoelectric efficiency improvement in nanostructured materials, a variety of challenges have nevertheless resulted in few demonstrations of these materials for large-scale waste heat recovery. Here we demonstrate a high-performance TEG by combining high-efficiency nanostructured bulk materials with a novel direct metal brazing process to increase the device operating temperature. A unicouple device generates a high power density of 5.26Wcm−2 with a 500°C temperature difference between hot and cold sides. A 1kW TEG system is experimentally demonstrated by recovering the exhaust waste heat from an automotive diesel engine. The TEG system operated with a 2.1% heat-to-electricity efficiency under the average temperature difference of 339°C between the TEG hot- and cold-side surfaces at a 550°C exhaust temperature. The high-performance TEG reported here open up opportunities to use TEGs for energy harvesting and power generation applications.