Sustainable thermoelectric materials based on metallic alloys and intermetallic compounds

Abstract

This review provides an overview of recent advances in metallic and intermetallic alloys, which have emerged as promising alternatives to traditional semiconductor thermoelectrics for power generation and active solid-state cooling. Driven by the abundance, low toxicity, mechanical robustness, and manufacturability of these materials, we examine current trends in metallic (e.g., Cu–Ni, Ni–Fe, Ni–Au) and intermetallic (Heuslers, skutterudites, Zintl phases, silicon-rich silicides, clathrates, stannides, etc.) families to gain insight into the physical basis of their performance and to inform future developments. Unlike the traditional focus on high-zT semiconductors, we highlight the importance of high-power factor (PF = σ·S2) in these materials for achieving compelling device-level performance, particularly for Peltier cooling under realistic thermal-resistance constraints. We also discuss phonon-engineering strategies to reduce lattice thermal conductivity while preserving electrical transport. The review concludes by exploring opportunities in thin films and microfabrication to unlock nanostructured architectures, conformal modules, and material-efficient devices. While some of the systems discussed (e.g., Ni–Au or Hf-rich half-Heuslers) are not intrinsically sustainable in terms of elemental abundance or cost, they are included to illustrate key physical mechanisms that can be translated to more sustainable material platforms.