Nanostructured half-Heuslers for thermoelectric waste heat recovery

热电材料将废热转化为有用的电能。即使是效率低下的热电发电回收也会对英国和全球的能源消耗产生重大影响，因为超过一半的一次能源最终被浪费为热能。到目前为止，热电发电机（teg）仅限于小范围应用，例如为旅行者号太空探测器提供动力，在这些应用中，耐用、可靠和低维护的发电是必不可少的。然而，热电能源收集器的市场预计将在10年内接近10亿美元。* teg的潜在应用包括从汽车尾气中收集热量，生产用于偏远、离网地区的热电联产装置，以及替代可穿戴微电子设备的电池。一个主要的限制是开发廉价、高效、不依赖有毒或稀缺资源的teg。例如，目前用于汽车热回收的最有效的热电材料是一种有毒的铅和稀缺的碲的化合物。在这个项目中，我们的目标是开发一种可行的、无毒的碲化铅teg替代品，使用“Heusler合金”，它结合了丰富的元素，如钛、镍和锡。它们也满足大多数工业对热电发电的要求，具有良好的热稳定性和机械稳定性，机械强度和易于加工。然而，TEG的热导率也很关键，优化Heusler合金的热导率一直是个问题。我们的目标是利用我们在赫斯勒合金合成和纳米结构方面的最新进展，这是目前英国在这一快速发展领域的唯一努力。本提案的最终目的是开发新的方法来控制Heusler合金的导热性，以建立一个性能与现有碲化铅器件相当的TEG原型。我们的见解是，存在各种合金相和故意缺陷，可用于在纳米尺度上引入结构织构，从而降低导热性。令人兴奋的是，这些结构中有许多以前没有被研究过。一个关键的方面是纹理的大小和分布，它应该足够长，以避免降低材料的导电性，但要足够短，以阻止热量的流动。我们将通过对加工条件对HA纳米级结构的影响进行系统研究，来研究纹理化的最佳长度尺度。我们将使用世界领先的电子显微镜、中子散射设备和理论建模来探测新材料的原子尺度结构和动力学，以优化合成参数。然后，我们将利用这些技术诀窍与我们的工业合作伙伴欧洲热力学有限公司合作，建立原型TEG模块。该合作项目涉及三家学术机构、国家设施和一家英国小企业，具有巨大的影响潜力，有望为降低英国的碳足迹做出贡献。它还为知识转移到一个充满活力的新行业和高质量的培训提供了极好的机会。*刘志强，“热电能量收集技术与应用”，2014

Thermoelectric materials convert waste heat into useful electric power. Even inefficient thermoelectric power generation recovery can have a substantial impact on UK and global energy consumption because more than half of primary energy is ultimately wasted as heat. So far, thermoelectric generators (TEGs) have been restricted to niche applications, such as powering the Voyager space probes, where durable, reliable and low-maintenance power generation is essential. However, the market for thermoelectric energy harvesters is projected to approach $1bn within a decade.* Potential applications for TEGs include scavenging heat from car exhausts, producing combined heat and power units for use in remote, off-grid locations, and replacing batteries in wearable microelectronic devices. A major limitation has been to develop cheap, efficient TEGs that do not rely on toxic or scarce resources. For example, the most efficient thermoelectric material for automobile heat recovery is currently a compound of toxic lead and scarce tellurium. In this project, we aim to develop a viable, non-toxic alternative to lead telluride TEGs, using 'Heusler alloys', which combine abundant elements such as titanium, nickel and tin. They also meet the majority of industrial requirements for thermoelectric power generation, having good thermal and mechanical stability, mechanical strength and ease of processing. However, a TEG's thermal conductivity is also critical and optimising the thermal conductivity of Heusler alloys has been problematic. We aim to capitalise on our recent advances in Heusler alloy synthesis and nanostructuring, which currently represents the only UK efforts in this fast-growing field.The ultimate aim of this proposal is to develop new means of controlling the thermal conductivity of Heusler alloys in order to build a TEG prototype of comparable performance to existing lead telluride devices. Our insight is that there are a variety of alloy phases and intentional defects that can be used to introduce structural texture on the nanoscale, thereby reducing the thermal conductivity. What is exciting is that many of these structures have not previously been studied. A critical aspect is the size and distribution of the texturing, which should be long enough to avoid reducing the material's electrical conductivity but short enough to impede the flow of heat. We will investigate the optimum length-scales for texturing by performing a systematic study of the impact of processing conditions on the HA nanoscale structure. We will use world-leading electron microscopy, neutron scattering facilities and theoretical modelling to probe the atomic-scale structure and dynamics of the new materials in order to optimise the synthesis parameters. We will then use this technical know-how in collaboration with our industrial partner European Thermodynamics Ltd. to build prototype TEG modules. This collaborative project, involving three academic institutions, national facilities and a UK small business, has substantial potential for impact, with notable prospects for making a contribution to lowering the UK's carbon footprint. It also provides excellent opportunities for knowledge transfer to a vibrant new industry and for high-quality training.* H. Zervos, "Thermoelectric Energy Harvesting 2014-2024: Devices, Applications, Opportunities," 2014