Feldhoff Armin
Institute of Physical Chemistry and Electrochemistry, Leibniz University Hannover, Callinstraße 3A, D-30167 Hannover, Germany.
Entropy (Basel). 2020 Jul 22;22(8):803. doi: 10.3390/e22080803.
The basic principles of thermoelectrics rely on the coupling of entropy and electric charge. However, the long-standing dispute of energetics versus entropy has long paralysed the field. Herein, it is shown that treating entropy and electric charge in a symmetric manner enables a simple transport equation to be obtained and the power conversion and its efficiency to be deduced for a single thermoelectric material apart from a device. The material's performance in both generator mode (thermo-electric) and entropy pump mode (electro-thermal) are discussed on a single voltage-electrical current curve, which is presented in a generalized manner by relating it to the electrically open-circuit voltage and the electrically closed-circuited electrical current. The electrical and thermal power in entropy pump mode are related to the maximum electrical power in generator mode, which depends on the material's power factor. Particular working points on the material's voltage-electrical current curve are deduced, namely, the electrical open circuit, electrical short circuit, maximum electrical power, maximum power conversion efficiency, and entropy conductivity inversion. Optimizing a thermoelectric material for different working points is discussed with respect to its figure-of-merit z T and power factor. The importance of the results to state-of-the-art and emerging materials is emphasized.
热电子学的基本原理依赖于熵与电荷的耦合。然而，关于能量与熵的长期争论长期以来使该领域陷入停滞。在此表明，以对称方式处理熵和电荷能够得到一个简单的输运方程，并推导出单一热电材料（而非器件）的功率转换及其效率。在一条单一的电压 - 电流曲线上讨论了材料在发电机模式（热电）和熵泵模式（电热）下的性能，该曲线通过将其与电开路电压和电闭路电流相关联以广义方式呈现。熵泵模式下的电功率和热功率与发电机模式下的最大电功率相关，而最大电功率取决于材料的功率因数。推导了材料电压 - 电流曲线上的特定工作点，即电开路、电短路、最大电功率、最大功率转换效率和熵导率反转。针对不同的工作点优化热电材料时，讨论了其品质因数z T和功率因数。强调了这些结果对现有和新兴材料的重要性。
