Front Matter
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Published:2022
Yueguang Deng, Jing Liu, "Front Matter", Liquid Metals for Advanced Energy Applications, Yueguang Deng, Jing Liu
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Liquid Metals for Advanced Energy Applications provides a systematic description and review of the basics and applications of low-melting-point liquid metal technology. It includes discussions of typical liquid metal materials and their energy-related technologies based on different mechanisms. The book draws directly on cutting-edge research from the authors' laboratory, where most of the progress in the use of low-melting-point liquid metals in advanced energy technologies has occurred.
This important book:
Provides solid foundational knowledge of basic concepts and applications of the latest liquid metals in the advanced energy field
Reviews low-melting-point liquid metals and their applications in the energy field
Includes meticulous coverage of typical liquid metal materials, including fluids, interface materials, phase change materials, and composites
Liquid Metals for Advanced Energy Applications is ideal for researchers and engineers in the advanced energy field, including general liquid metal science and technology. It is also suitable for university courses in the fields of energy and materials.
Preface
In the last two decades, tremendous efforts have been made to find and develop advanced energy materials to meet worldwide demands and achieve environmental targets. Among the various cutting edge materials, low-melting-point liquid metals have emerged as an important research topic and exhibited strong potential to contribute to the energy technologies. The advantages of liquid metals, such as low melting point, high thermal/electrical conductivity, large latent heat, non-flammability, non-toxicity, etc., render them extremely desirable in the energy field. Generally, the use of liquid metals can be classified into four broad categories, including applications in energy generation, energy transportation, energy storage, and energy utilization. For energy generation, liquid metal heat transfer technologies can be used to develop new solar thermal power generation systems and high-temperature waste heat recovery systems. Additionally, liquid metal thermoelectric generators can recover low-grade and low-temperature heat, whereas liquid metal magnetohydrodynamic (MHD) generators can produce electricity from ocean waves and human movements. During energy transportation, liquid metals can transfer an extremely high heat flux at high temperatures above 600 °C, with a convective heat transfer coefficient exceeding 10 000 W/(m2 K), which is difficult to manage via conventional fluids. Moreover, liquid metal electrical interface materials can significantly reduce power transmission loss. In terms of the energy storage, liquid metal phase-change materials are pure metal solid–liquid phase-change materials with high thermal conductivity and large latent heat. Therefore, they can transfer heat more efficiently and store more heat than paraffin for electronic cooling and solar energy storage. Moreover, liquid metal batteries are promising for large-scale energy storage and flexible electronic power supplies. Finally, for energy utilization, liquid metal technology enables various methods to reduce energy consumption. Liquid metal convection and thermal interface materials can effectively cool energy devices (e.g., LEDs and IGBTs) to improve efficiency and reduce power consumption. Moreover, liquid metal catalysts are promising energy-saving materials because they accelerate chemical reactions and optimize energy utilization processes. Therefore, low-melting-point liquid metals can contribute significantly to the entire energy chain.
The liquid metals presented in this book refer to low-melting-point alloys [primarily gallium (Ga)-based and bismuth (Bi)-based alloys], which own melting points below 200 °C and are nonflammable and nontoxic. Therefore, they differ from conventional heat transfer metals or alloys, such as mercury (Hg), lithium (Li), sodium–potassium (NaK), molten tin (Sn), and lead-bismuth (PbBi), which generally have high melting points above 200 °C (Sn) or display flammability (Li and NaK) and toxicity (Hg and PbBi). Although these conventional liquid metals have been used for nearly a century in nuclear reactors, it is only in the last two decades that a more concerted effort has been directed specifically toward using gallium- and bismuth-based liquid metals for more energy-related applications. In 2002, Liu (author of this book) et al. proposed, for the first time, the use of low-melting-point liquid metals as an ideal coolant for the thermal management of high power chips and performed a series of fundamental research to evaluate the heat transfer of liquid metals, including studies pertaining to liquid metal material synthesis, physical property measurement, material compatibility, convective capability, electromagnetic operation, and heat transfer enhancement, along with applications, including electronics cooling, waste heat recovery, and solar power generation. Subsequently, as the understanding of liquid metals deepened, more mechanisms related to energy were explored and application areas were expanded, such as liquid metal-based interface heat/electrical transport, phase-change heat storage, thermoelectric generation, MHD power generation, hydrogen generation, batteries, and catalysts. Particularly in the last decade, liquid metals have gradually attracted significant attention in international academia. The great efforts of worldwide scholars have further enriched the research findings of liquid metals and have contributed to the flourishing of this field.
Currently, low-melting-point liquid metals have exhibited unique values in the energy field in both academia and industry, and significant advances have been achieved. However, to the best of our knowledge, a systematic monograph to describe low-melting-point liquid metals and their applications in the energy field is not available hitherto. Therefore, in this book, we review liquid metal materials and introduce their energy-related technologies based on different mechanisms, including liquid metal convection for heat transfer and energy utilization, liquid metal interface materials for enhancing heat and electrical transport, liquid metal phase-change materials for thermal energy storage, liquid metal thermoelectric generators for thermal energy conversion, liquid metal MHD power generation for mechanical and thermal energy harvesting, liquid metal batteries, liquid metal catalysts, and liquid metal-mediated direct aluminum–water reactions for hydrogen energy. Both the fundamental mechanism and a broad variety of energy applications are elaborated. Moreover, the scientific and technical challenges are summarized, and the outlook for liquid metal technologies in the energy field is discussed. We hope this book can provide an important scientific reference for liquid metal materials and their application for advanced energy generation, transportation, storage, and utilization in the near future.
Over the past few years, a group of our colleagues, post-doctoral research fellows, graduate students, and collaborators have made important contributions to this area. Without their persistence, patience, and creativity, presenting this book with brand new fundamentals and technical categories would be impossible. At the end of finalizing this book, the authors would like to express their sincere appreciation to those people who have offered their professional contribution: Professor Zhongshan Deng, Professor Yixin Zhou, Professor Wei Rao, Professor Lei Sheng, Professor Qian Wang, Professor Lei Wang, Dr. Kunquan Ma, Dr. Yunxia Gao, Dr. Haiyan Li, Dr. Xiaohu Yang, Dr. Sen Chen, Dr. Fujun Liu, Dr. Dewei Jia, Dr. Shuting Liang, Dr. Hongzhang Wang, Dr. Shuo Xu, Dr. Jianbo Tang, Dr. Sicong Tan, Dr. Yang Yu, Dr. Jie Zhang, Mr. Haoshan Ge, Mr. Shengfu Mei, Mr. Xiangyang Xiao, Mr. Peipei Li, Mr. Kaiwang Xie, and Mr. Teng Li. We also wish to thank the AIP Publishing editors Claire Gordon, Dr. Benjamin Johnson, and Martine Felton for their invitation, encouragement, and valuable help in the initiation and completion of the tough task of preparing this book. Last but not least, the authors of this book would like to acknowledge the generous support from the Frontier Project of the Chinese Academy of Sciences, the Special Foundation of President of the Chinese Academy of Sciences, the NSFC Key Project, the Tsinghua University Initiative Scientific Research Program, and the Beijing Institute of Technology Research Fund Program for Young Scholars. Many thanks for their valuable support toward making this book a reality.
We humbly hope that this book will serve as a starting point for academics and industrial society to quickly grasp the basics of liquid metal materials and their applications in the energy field and thus better advance this area. Any critical comments and constructive suggestions from the readers for us to further enhance our book are highly welcome and will be incorporated in future possible updated versions.
Yueguang Deng and Jing Liu
Beijing, China
January 2022