Hu Qiujun, Luo Ding, Guo Junbiao, Qiu Wenbin
College of Physics, Sichuan University, Chengdu 610065, China.
Faculty of Engineering, University of Nottingham, University Park, Nottingham 999020, U.K.
ACS Appl Mater Interfaces. 2023 Aug 16;15(32):38623-38632. doi: 10.1021/acsami.3c08116. Epub 2023 Aug 7.
Thermoelectric (TE) energy conversion technology provides a promising way to improve the efficiency of fossil energy by generating electricity from low-grade waste heat. With regard to these applications, thermoelectric generators (TEGs) should be designed from system integration perspectives to simultaneously improve heat transfer efficiency and system simplification as well as the robust mechanical properties. However, typical TEGs fabricated by conventional methods barely accomplish such requirements. Herein, high-quality TEGs were assembled by combining the well-flowable spherical bismuth telluride (BT) powdered precursors and selective laser melting (SLM) technology. By optimizing the electronic and phonon transport properties through defect engineering driven by 3D printing, a high figure of merit was accomplished for 1.27 (p-type) and 1.13 (n-type) in BT. This achievement is primarily attributed to the nonequilibrium solidification mechanism, which leads to the formation of multiscale defects during the 3D printing process. The introduction of these multiscale defects enables the effective scattering of wide frequency phonons, leading to a substantial reduction in lattice thermal conductivity. Meanwhile, robust mechanical properties were obtained in the printed p-type/n-type BT TE materials parallel to the building direction (BD) with a compressive strength reaching 257/250 MPa by employing the fine grain structure and the high density of nanotwins introduced during the SLM process. A well shape-controllable and high-performance TEG was designed using 3D-printed BT half-rings, and an output power of 134 mW was achieved at a temperature gradient of 38.9 °C. Our study opens a new route for the great potential of TE materials based on standard commercial SLM 3D printing technology for low-grade waste heat emitted from structures with heterogeneous shapes.
热电（TE）能量转换技术为通过从低品位废热发电来提高化石能源效率提供了一条很有前景的途径。对于这些应用，应从系统集成的角度设计热电发电机（TEG），以同时提高传热效率、简化系统以及增强机械性能。然而，通过传统方法制造的典型TEG几乎无法满足这些要求。在此，通过将流动性良好的球形碲化铋（BT）粉末前驱体与选择性激光熔化（SLM）技术相结合，组装出了高质量的TEG。通过由3D打印驱动的缺陷工程优化电子和声子传输特性，在BT中实现了1.27（p型）和1.13（n型）的高优值。这一成果主要归因于非平衡凝固机制，该机制在3D打印过程中导致形成多尺度缺陷。这些多尺度缺陷的引入使得宽频声子能够有效散射，从而大幅降低晶格热导率。同时，通过采用SLM过程中引入的细晶粒结构和高密度纳米孪晶，在与构建方向（BD）平行的印刷p型/n型BT TE材料中获得了稳健的机械性能，抗压强度达到257/250 MPa。使用3D打印的BT半环设计了一种形状可控且高性能的TEG，在38.9℃的温度梯度下实现了134 mW的输出功率。我们的研究为基于标准商业SLM 3D打印技术的TE材料在从具有异质形状的结构中排放的低品位废热方面的巨大潜力开辟了一条新途径。
