Citation: Yatsyshyn, S.; Hotra, O.; Skoropad, P.; Bubela, T.; Mykyichuk, M.; Kochan, O.; Boyko, O. Investigating Thermoelectric Batteries Based on Nanostructured Materials. Energies 2023, 16, 3940. https://doi.org/10.3390/ en16093940 Academic Editor: Guiqiang Li Received: 8 April 2023 Revised: 1 May 2023 Accepted: 6 May 2023 Published: 7 May 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). energies Article Investigating Thermoelectric Batteries Based on Nanostructured Materials Svyatoslav Yatsyshyn 1 , Oleksandra Hotra 2, * , Pylyp Skoropad 1 , Tetiana Bubela 1 , Mykola Mykyichuk 1 , Orest Kochan 1 and Oksana Boyko 3 1 Department of Information-Measuring Technologies, Lviv Polytechnic National University, Stepana Bandery St, 12, 79013 Lviv, Ukraine 2 Department of Electronics and Information Technology, Lublin University of Technology, Nadbystrzycka 38D, 20-618 Lublin, Poland 3 Department of Medical Informatics, Danylo Halytsky Lviv National Medical University, Pekarska St, 69, 79000 Lviv, Ukraine * Correspondence: o.hotra@pollub.pl Abstract: This article discusses the characteristics of the design of thermoelectric generators (TEGs) for cold climates. Since the thermocouples of thermoelectric batteries are produced from different materials, their major properties are studied. Particular attention is given to nanostructured materials regarding the modern class of thermoelectric materials. Two-, three-, and four-component alloys (metallic glasses) of the Fe-Ni(Cu)-P-B system are chosen based on the experience of thermoelectric thermometry. The close chemical composition of two thermoelectrodes enables their compatibility in thermocouple production and satisfactory thermoelectric efficiency of batteries during long-term operation. The improvement of the thermoelectric battery characteristics related to a unit of mass is evaluated. The materials studied are distinguished by the absence of toxic components harmful to the environment at the manufacturing and operating stages. Keywords: thermoelectric generator; thermoelectric battery; thermocouple; nanostructured material; metallic glass 1. Introduction Thermoelectric generators seem to be effective as a part of waste heat recovery sys- tems [1]. In creating TEGs, there is a tendency to search for new constructive solutions based on the use of nontraditional materials. This is due to the presence of new oper- ational conditions and environments, and, mainly, the need to improve the operational performance of the designed thermoelectric converters [2]. The relevance of creating TEGs has become undeniable for the production of electricity in remote areas of the North [3], including for the cathodic protection of gas pipelines, their telemetry, etc. In areas without extensive electrical networks, the advantages of their use are indisputable. This requires working out the technological [4], scientific, and technical aspects, in particular the issues related to materials based on modern approaches to their design. A significant number of thermoelectric materials for different temperature ranges and regimes are known [5–7]. However, there are still ambiguities regarding both the selection of the materials themselves and the formation of methods, means, and methodologies for their optimisation, according to a spectrum of operational and other characteristics. For example, there are problems in the evaluation of thermoelectric efficiency (figure of merit ZT) for enhancing thermoelectric materials. It might be better to estimate the needed materials by other coefficients, for instance by their long-term stability [8]. Thus, it is important to choose the technologies (namely nanotechnologies) to improve the required characteristics [9]. Energies 2023, 16, 3940. https://doi.org/10.3390/en16093940 https://www.mdpi.com/journal/energies