Here we demonstrate low-cost polycrystalline antimonides for much more productive thermoelectric waste-heat recovery within 600 K than standard tellurides. This can be enabled by a structure of Ni/Fe/Mg3SbBi and Ni/Sb/CdSb contacts for both a avoidance of chemical diffusion plus a small interfacial resistivity, realizing a record and secure module efficiency https://hydrocarbon-heat-pumps89011.fireblogz.com/62528663/not-known-factual-statements-about-hydrocarbon-heat-pumps