Enhanced Thermoelectric Performance of PbBi ₂ Te ₄ through Solid-State Lithiation

PbBi 2 Te 4 is regarded as a promising thermoelectric material due to its complex ternary layered structure. However, its intrinsically high carrier concentration limits its thermoelectric performance. To address this issue, Ni and Se doping was initially employed to modulate the carrier concentration. Nonetheless, the modest enhancement achieved through doping alone suggests that this strategy is insufficient to substantially improve the thermoelectric properties of PbBi 2 Te 4 . Subsequently, solid-state lithiation was systematically investigated as an alternative approach. The incorporation of Li ions into the PbBi 2 Te 4 matrix effectively reduced the thermal conductivity, leading to a significant enhancement in thermoelectric performance. Specifically, after solid-state lithiation of the Ni- and Se-co-doped sample (PbNi 0.04 Bi 1.96 Te 3.6 Se 0.4 ), a maximum figure of merit (ZT) of 0.54 was achieved at 590 K, corresponding to a 68% improvement over the ZT max of pristine PbBi 2 Te 4 . Furthermore, an average ZT of 0.41 was obtained in the temperature range of 300–650 K, representing a 140% increase compared to that of the pristine sample over the same temperature range. These findings offer valuable insights for the further development of PbBi 2 Te 4 -based thermoelectric materials.