Remarkably high thermoelectric performance of Cu2−xLixSe bulks with nanopores

Abstract

Cu₂Se is a p-type semiconducting compound that possesses excellent thermoelectric properties which exhibit great potential for practical applications. In recent years, there have been many ways to improve thermoelectric properties. Reducing the thermal conductivity is a very effective way to obtain high performance thermoelectric materials. In this study, a series of Cu_2−xLi_xSe (x = 0, 0.01, 0.02 and 0.03) polycrystalline bulk samples were successfully prepared by hot-pressing the nanopowders made by hydrothermal synthesis to investigate the doping effects of Li on the phase structure, microstructure and thermoelectric properties of Cu₂Se. Compared with the Li-free Cu₂Se, the introduction of Li element increases the Seebeck coefficient. Importantly, both nanopores and Li substitution were observed which can reduce κ_Lvia increased scattering phonons. At 973 K, the Cu_1.98Li_0.02Se sample presented an excellent ZT of 2.14.