Gradient-free thermo-electrochemical energy conversion based on ceramic intercalation materials

虽然技术设施、地热源和人类本身会永久地散发出相当大功率的热量，但这些热源的温度水平太低，无法利用普通技术直接将热量转换为电力进行经济回收。最近，电化学过程作为现有热电转换技术的可能替代方案引起了强烈的关注，因为它们具有更有效和更便宜的潜力。在所提出的项目的框架和非常有前途的初步测试的基础上，一种新的电化学电池概念的热电转换使用陶瓷插层化合物进行了研究。具有相似电极电势和尽可能高的相反反应熵的亚化学计量嵌入化合物（例如基于Li、Na、K）用作阳极和阴极材料。细胞温度的变化（无梯度！）根据阳极和阴极反应各自的熵感应电池电压。电池实际上是由温度变化充电的（类似于热电材料）。在放电（发电）期间，插层化合物的主体晶格分别被氧化和还原，伴随着碱金属离子的提取和插入，直到电池电压趋向于0 V。在极性反转并回到初始温度之后，电池可以再次放电并恢复初始状态。与现有的废热利用和能量收集技术相比，所描述的工作原理可能具有显著的益处。然而，鉴于其新奇以及缺乏基础研究和实验数据，目前无法证实这一说法。基于非常有希望的初步研究，申请人努力对使用典型陶瓷插层材料的热电化学热电转换有基本的理解。这包括关于工作原理的机理研究以及所用插层化合物的性质与所得热电化学电池之间的基本关系。最后，基于实验的见解，将开发一个模型，描述热-电化学的热电转换，这可能是前瞻性地用于识别合适的材料和设计性能。

Although technical facilities, geothermal sources and humans themselves permanently emit heat of considerable power, the temperature level of these heat sources is too low for economic recovery using common technologies for direct heat to electricity conversion. Recently, electrochemical processes attracted intense attention as a possible alternative to existing technologies for heat to electricity conversion, since they have the potential to be much more effective and less expensive. In the framework of the proposed project and based on very promising preliminary tests, a novel electrochemical cell-concept for heat to electricity conversion using ceramic intercalation compounds is investigated. Substoichiometric intercalation compounds (e.g. based on Li, Na, K) with similar electrode potentials and as high as possible opposite reaction entropy are used as the anode and cathode material. A change in the cells’ temperature (no gradient!) induces a cell voltage according to the respective entropies of the anode and cathode reaction. The cell is literally charged by the temperature change (analogously to a pyroelectric material). During discharging (power generation), the host lattices of the intercalation compounds are oxidized and reduced, respectively, accompanied with the extraction and insertion of the alkali metal ion, until the cell voltage tends towards 0 V. This process is completely reversible. After polarity reversal and return to the initial temperature, the cell can be discharged again and the initial state is restored. The described working principle might have significant benefits compared to existing technologies for waste heat utilization and energy harvesting. However, in light of its novelty and the absence of basic research and experimental data, this statement cannot be confirmed at the moment. Based on very promising preliminary investigations, the applicants strive for a fundamental understanding of the thermo-electrochemical heat to electricity conversion using typical ceramic intercalation materials. This includes mechanistic studies regarding the working principle as well as basic relationships between the properties of the intercalation compounds used and the resulting thermo-electrochemical cells. Finally, based on the experimental insights, a model will be developed describing the thermo-electrochemical heat to electricity conversion, which might be used prospectively for the identification of suitable material and design properties.