Thermoelectric Modules Incorporating MgAgSb and Mg ₃ (Sb,Bi) ₂ Synthesized Using a Melting Method

Thermoelectric energy conversion has attracted notable attention as a promising technology for generating electricity from waste heat. At present, Bi ₂ Te ₃ system is the only material used in commercial thermoelectric modules. Despite extensive research into alternative materials, Bi ₂ Te ₃ has consistently demonstrated the best near room temperature thermoelectric performance for over 50 years. On the other hand, recent studies have identified MgAgSb and Mg ₃ (Sb,Bi) ₂ as high‐performance p‐type and n‐type thermoelectric materials, respectively. Furthermore, MgAgSb/Mg ₃ (Sb,Bi) ₂ modules have been reported to achieve high conversion efficiency. However, these compounds are typically synthesized by ball milling, a process unsuitable for large‐scale production. Suitable replacements for Bi ₂ Te ₃ modules must exhibit both high conversion efficiency and have simple synthesis procedures. To fulfill the requirements, a scalable synthesis method for MgAgSb based on melting and annealing is established, without grinding or hot pressing. MgAgSb/Mg ₃ (Sb,Bi) ₂ modules incorporating thus obtained MgAgSb elements generate electrical power comparable to conventional Bi ₂ Te ₃ modules when tested in a system with an air‐cooled heat exchanger, reflecting practical application conditions. These results suggest that MgAgSb/Mg ₃ (Sb,Bi) ₂ modules are promising alternatives to commercial Bi ₂ Te ₃ modules.