Enhancement of the thermoelectric properties of (Ba0.15Pb0.15Ag0.1Na0.2Cu0.2Bi1.2)Sr2Co2Oy ceramics by high-entropy engineering

Bi 2 Sr 2 Co 2 O y has good thermoelectric performance, but it still has wide room for further improvement. In this study, the (Ba 0.15 Pb 0.15 Ag 0.1 Na 0.2 Cu 0.2 Bi 1.2 )Sr 2 Co 2 O y high-entropy sample was prepared by the Bi 2 Sr 2 Co 2 O y pristine sample and the multi-element doping in Bi cite. On the one hand, the carrier concentration and carrier mobility of the high-entropy sample increase, so its electrical transport performance is improved greatly. On the other hand, due to the high disorder introduced by the multi- element doping, the phonon scattering is enhanced, and the thermal conductivity of the high-entropy sample is suppressed significantly. Finally, at 923 K, the ZT value (the dimensionless thermoelectric figure of merit) of the high-entropy sample reaches 0.26, which is about 1.9 times higher than that of the pristine sample.