Abstract High power factor and low thermal conductivity are imperative to maximize the energy conversion efficiency of thermoelectric materials. Constantan (Cu–Ni alloy), a widely-used material for thermocouples, has higher power factor (∼12000 μW m−1 K−2 at 950 K) [Mao et al. 2015] than the classic Bi2Te3-based thermoelectric materials (∼4500 μW m−1 K−2 at 300 K) [Poudel et al. 2008]. However, the high thermal conductivity restricts its thermoelectric performance. In this work, we demonstrate that, the thermal conductivity of Cu–Ni alloy can be effectively reduced from 48.1 to 9.6 W m−1 K−1 at 873 K by introducing carbon nanotubes (CNTs), and the thermoelectric performance is remarkably improved with the figure of merit (zT) being up to 0.41, an enhancement of about 141% over the pristine Cu–Ni alloy. Negative correlation between the total thermal conductivity of hybrid composite and the specific surface area of CNTs is further identified. The thermal conductivity suppression mechanism is ascribed to the introduction of both porous structures and carbon-nanotube-metal interfaces. Our studies provide a promising and general strategy to enhance the thermoelectric properties of materials with high thermal conductivity.

中文翻译：

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通过引入碳纳米管提高铜镍合金的热电性能

摘要 高功率因数和低热导率是热电材料能量转换效率最大化的必要条件。康铜（Cu-Ni 合金）是一种广泛用于热电偶的材料，具有更高的功率因数（~12000 μW m-1 K-2 at 950 K）[Mao et al. 2015] 比经典的基于 Bi2Te3 的热电材料（~4500 μW m-1 K-2 at 300 K）[Poudel et al. 2008]。然而，高热导率限制了其热电性能。在这项工作中，我们证明，通过引入碳纳米管 (CNT)，可以将 Cu-Ni 合金的热导率在 873 K 时有效地从 48.1 W m-1 K-1 降低到 9.6 W m-1 K-1，并且热电性能显着提高品质因数 (zT) 高达 0.41，比原始 Cu-Ni 合金提高了约 141%。进一步确定了混合复合材料的总热导率与 CNT 的比表面积之间的负相关性。导热抑制机制归因于多孔结构和碳纳米管金属界面的引入。我们的研究提供了一种有前景的通用策略来增强具有高导热性的材料的热电性能。