Electrochemical energy storage (EES) is increasingly critical for development and applications of numerous technologies or new products, such as portable electronics, electric vehicles, and large-scale energy storage systems. The expanding market of EES requires products that are low cost, environmentally friendly, and with high energy density. Natural proteins are abundant bio-macromolecules and possess numerous useful functional groups through millions of years of evolution. By the rational control of the protein molecular architectures, we can effectively develop important component materials with functionalities for energy storage systems via appropriately utilizing the functional groups of proteins. Therefore, tremendous research efforts on application of natural proteins for enhancing the performance of EES have been reported. In this book, advanced strategies for adopting various natural proteins to development of the components of EES are comprehensively summarized, such as protein-derived active materials, separators, binders, electrolytes, and more. The advantages and challenges of the various strategies are discussed in detail. Finally, future perspectives of the protein-based strategies toward high-performance EES are proposed. "Despite fruitful research on natural protein-based materials for electrochemical energy systems, there is no book with systematic and profound discussion on the subject, until now. This volume is a valuable and timely addition to current catalogues in biomaterials, energy systems and sustainability, and it is expected to be a delightful and also though-provoking reading for students, educators and researchers from academia and industry." Bin Li Associate Professor, Wichita State University, USA "This is a timely publication to introduce the recent progress of protein applications in energy storage devices. Protein engineering has been used in the biomedical and tissue engineering fields but is still novel in energy storage applications. Such a summary of the global research on engineered proteins for energy storage benefits academia and industry alike and would help to propel further development of the field." Long Jiang Associate Professor, North Dakota State University, USA Dr Chenxu Wang is a Research Associate at the Batteries and Energy to Advance Commercialization and National Security (BEACONS) center in Dallas, Texas, USA. He earned his PhD from Washington State University in 2023 under the supervision of Dr Weihong Zhong. He has been engaged in battery research since 2016 and has approximately one year of industry experience in battery manufacturing. His research focuses on anodes, cathodes, separators, electrolytes, battery recycling, and automated synthesis and characterization. He serves as a Youth Editorial Board member for Exploration and a Guest Editor for Batteries. In 2023, he received the Outstanding Dissertation Award and the Outstanding Research Assistant Award at Washington State University. As the lead author, he has published 10 peer-reviewed journal articles and one book. Dr Wei-Hong Zhong is Professor at the School of Mechanical and Materials Engineering, Washington State University (WSU), USA, where she was previously Westinghouse Distinguished Professor (2012–2020). She is an elected Fellow of the American Association for the Advancement of Science (AAAS, 2016). She has won several awards, including the Academic Advisor Excellence Award (WSU, 2013), Outstanding Researcher Awards (WSU, 2011, 2013), and the Dow Chemical Composites Educator of the Year Award (Society of Plastic Engineering, 2011). She has published two books and over 300 peer-reviewed papers, with an H-index of 56.