Abstract: With the advantages of material-saving shapable production and facile geometry design, shapable methods provide a broad prospect for the future thermoelectric material production. Herein, cold spraying followed by annealing (CSA) induces enriched defects in the bulk material, which can lead to excellent thermoelectric performance and hardness. Compared with the HP process, CSA contributes to more pores and intrinsic defects. The enriched intrinsic defects contribute to moderate electrical performance. Simultaneously, these defects strongly scatter phonons, leading to ultra-low total thermal conductivity values of ∼0.64 W m^-1 K^-1 for both p-type CSA Bi_0.5 Sb_1.5 Te₃ and n-type CSA Bi₂ Te_2.7 Se_0.3 bulks at room temperature. Correspondingly, CSA bulks possess excellent room-temperature zT of ∼1.1 (p-type Bi_0.5 Sb_1.5 Te₃) and ∼0.9 (n-type Bi₂ Te_2.7 Se_0.3), respectively, which are comparable to those prepared by HP and other shapable methods. Furthermore, a four-leg thermoelectric device is assembled based on as-prepared p-type CSA Bi_0.5 Sb_1.5 Te₃ and n-type CSA Bi₂ Te_2.7 Se_0.3 bulks, achieving a rational energy conversion efficiency of ∼4% under a small temperature difference of 100 K. This study demonstrates CSA method is promising for future shapable production of high-performance thermoelectric materials.

Key words: Cold spraying, Shapable method, Thermoelectric, Bi₂Te₃, Bulk