Enhanced Thermoelectric Performance of Yb-Single-Filled Skutterudite by Ultralow Thermal Conductivity
作者:Wenjie Li、Jue Wang、Yuantao Xie、Jennifer L. Gray、Jean J. Heremans、Han Byul Kang、Bed Poudel、Scott T. Huxtable、Shashank Priya
DOI:10.1021/acs.chemmater.8b03994
日期:2019.2.12
The filling fraction limitation (FFL) in n-type CoSb3 skutterudites is far below that of p-type (Fe,Co)Sb3-based skutterudites, and it is critical to increase FFL for accomplishing high thermoelectric figure of merit (ZTmax). Here, a series of YbxCo4–yFeySb12 alloys with x = 0.25–0.5 and y = 0.1–0.5 were synthesized, which demonstrate a clear increase of the FFL of Yb from ∼0.3 in CoSb3 to 0.5. Ultralow thermal conductivities of 2.0–2.5 W/m·K at 300 K and 1.75 W/m·K at ∼600 K have been achieved, which are the lowest values reported among skutterudite materials and comparable with p-type skutterudites. These ultralow thermal conductivities result from the combination of secondary phase scattering and phonon scattering from dynamic electron exchange between Fe2+ and Co3+. High ZTmax values of 1.28 at 740 K and 1.34 at 780 K are obtained, which are among the best values reported in the temperature range of 740–800 K. The temperature at which maximum ZTmax appears is shifted below 850 K. These results are highly exciting toward the development of multistage segmented and cascade thermoelectric power generators for in-air operations.
n 型 CoSb3 硅钙钛矿的填充分数限制(FFL)远低于 p 型(Fe,Co)Sb3 硅钙钛矿的填充分数限制,因此提高填充分数限制对于获得高热电性能(ZTmax)至关重要。本文合成了一系列 x = 0.25-0.5 和 y = 0.1-0.5 的 YbxCo4-yFeySb12 合金,结果表明 Yb 的 FFL 明显从 CoSb3 中的 0.3 增加到 0.5。在 300 K 和 ∼ 600 K 的超低热导率分别为 2.0-2.5 W/m-K 和 1.75 W/m-K,这是目前所报道的矽卡岩材料中的最低值,与 p 型矽卡岩相当。这些超低导热系数是由 Fe2+ 和 Co3+ 之间动态电子交换产生的次相散射和声子散射共同作用的结果。在 740 K 和 780 K 时分别获得了 1.28 和 1.34 的高 ZTmax 值,这是在 740-800 K 温度范围内报告的最佳值之一。