Cold Spray Additive Manufacturing of Thermoelectric Generators*

Thermoelectric generators (TEGs) provide a pathway to recovering and converting thermal energy directly into electricity. Adoption of the technology has often been limited due to the difficulty of manufacturing TEGs that can be incorporated into industrial environments where waste heat is prevalent. To address this shortcoming an additive manufacturing technique has been developed for the fabrication of arbitrary shape Bi₂Te₃ based (and other semiconductors) thermoelectric generators, promising greater design flexibility to harvest low grade waste heat. We have demonstrated that cold-spraying of powdered material yields near-full density parts, without significant loss of thermoelectric properties in the operating window of ~100 C. A systematic study is presented of the structural characteristics for the deposited material, correlated with thermal and electrical transport measurements to allow further understanding of the thermoelectric efficiency in the cold-sprayed samples. In particular cold spraying allows deposition on curved geometries such as copper pipes, and produces thermoelectric materials with Seebeck coefficients comparable to the bulk starting material.