Entropy engineering and interface optimization in materials for highly effective thermoelectric energy conversion

用于高效热电能量转换的材料熵工程和界面优化

• 批准号: 520487260
• 负责人: Dr. Johannes de Boor
• 金额: --
• 依托单位: Lehrstuhl Werkstoffe der Elektrotechnik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/520487260?language=en
• 关键词: Entropy; engineering; interface; optimization; materials

Generators from thermoelectric materials can convert waste heat into electricity and contribute to a sustainable energy supply by reducing the consumption of fossil fuels and the emission of CO2. However, the exploitation of thermoelectric generator technology remains limited due to moderate efficiency, unsolved challenges in material-specific joining technologies and concerns on sustainability because of the current involvement of toxic and rare elements. A concerted effort of leading laboratories from AGH-UST (Poland), UDE and DLR (Germany) will address these challenges, aiming at developing highly effective thermoelectric materials from the families of argyrodites and magnesium silicide-based solid solutions, qualifying them for the usage in inexpensive and eco-friendly energy converters. We propose the following strategies: 1. Exploitation of an Entropy Engineering (EE) approach to stabilize the favorable high-symmetry a-phase in argyrodites at lower temperatures, to allow for the synthesis of novel argyrodites with a favorable electronic band structure and to increase the dopant solubility for both argyrodites and magnesium silicide-based solid solutions. 2. Synthesis of multiphase samples with structuring at the nm-scale. Nanostructuring can be achieved by controlled unmixing making use of the miscibility gap (for magnesium silicide based solid solutions) or secondary phases (argyrodites) by adjustment of the configurational entropy. Enhancement of the thermoelectric properties of the materials can be expected due to a combination of increased phonon scattering and an energy filtering of detrimental charge carriers at formed internal interfaces. The effect of advanced strategies like multiple, composition-dependent doping in multiphase composites can be evaluated directly employing Kelvin Probe Force Microscopy for electrical and Scanning Thermal Microscopy for thermal characterization with a spatial resolution of several 10 nm, rarely applied to thermoelectric materials before. 3. These AFM-based scanning techniques will also be employed to determine electrical and thermal contact resistances of Mg2X and argyrodites joined to selected electrode materials as these electrodes are a prerequisite to operate the functional materials in a device. Making use of the superb spatial resolution we’ll trace the microscopic origin of the thermal along with the electrical resistances of external interfaces and identify experimental levers to reduce them. Local measurements, microstructural characterization and transport modelling will be used to understand the integral thermoelectric performance. Experimental efforts in material development will be supported by first-principle based electronic band structure calculations. Finally, a magnesium silicide/argyrodite pn-uni-couple prototype shall be fabricated so that the tremendous application potential of this promising material combination can be evaluated also from an assembly point of view.

热电材料发电机可以将废热转化为电力，并通过减少化石燃料的消耗和二氧化碳的排放来促进可持续能源供应。然而，热电发电机技术的开发仍然有限，原因是效率中等，材料特定连接技术的挑战尚未解决，以及由于目前涉及有毒和稀有元素而对可持续性的担忧。来自AGH-UST（波兰），UDE和DLR（德国）的领先实验室的共同努力将解决这些挑战，旨在开发来自Argyrodite和硅化镁基固溶体家族的高效热电材料，使其有资格用于廉价和环保的能源转换器。我们提出以下策略：1.利用熵工程（EE）方法在较低温度下稳定银矿中有利的高对称性α相，以允许合成具有有利电子能带结构的新型银矿，并增加银矿和硅化镁基固溶体的掺杂剂溶解度。2.纳米尺度结构化多相样品的合成。纳米结构化可以通过利用可混性间隙（对于基于硅化镁的固溶体）或通过调整构型熵的第二相（argyrodite）来控制解混来实现。由于声子散射增加和在形成的内部界面处有害电荷载流子的能量过滤的组合，可以预期材料的热电性质的增强。多相复合材料中的多种成分依赖性掺杂等先进策略的效果可以直接使用Kelvin探针力显微镜进行电学表征，使用扫描热显微镜进行热表征，空间分辨率为10 nm，以前很少应用于热电材料。3.这些基于AFM的扫描技术也将用于确定连接到所选电极材料的Mg 2X和argyrodite的接触电阻和接触热阻，因为这些电极是操作器件中的功能材料的先决条件。利用高超的空间分辨率，我们将跟踪热的微观起源沿着与外部接口的电阻，并确定实验杠杆，以减少他们。局部测量，微观结构表征和运输建模将用于了解整体热电性能。材料开发的实验工作将得到基于第一原理的电子能带结构计算的支持。最后，一个硅化镁/argyrodite pn单耦合原型应制造，使这种有前途的材料组合的巨大应用潜力，也可以从组装的角度进行评估。