High-pressure synthesis of phonon-glass electron-crystal featured thermoelectric LixCo4Sb12

Li-filled CoSb3, which is inaccessible under ambient pressure, was successfully synthesized with a high-pressure synthesis technique, demonstrating a fast and effective way to broaden elemental species that can be filled into voids of skutterudites. The optimized Li0.36Co4Sb12, with a greatly enhanced thermal power factor and much reduced thermal conductivity, has a ZT value of 1.3 at 700 K, the highest among all single elemental filled CoSb3 materials at this temperature. In addition, an instructive linear relationship between the Einstein temperatures of the distinct rattling fillers and their ionic radii is revealed, which as a reference can easily be applied to the multiple elemental filling strategy for selecting suitable filling elemental species to reduce the lattice thermal conductivity more effectively.