Metal-ion capacitors based on monovalent and multivalent ions show great potential to replace existing battery materials in fields where both high energy and high power densities are simultaneously required. This book provides a comprehensive understanding of this cutting-edge energy storage technology, exploring the underlying principles, materials, and design considerations. The book offers practical guidance, including fabrication techniques, design strategies, and characterization methods, enabling readers to implement technological advancements effectively. It explores diverse applications of metal-ion capacitors across industries such as renewable energy, electric vehicles, and consumer electronics, fostering the development of more sustainable and efficient energy solutions. The book will empower researchers, engineers, and students alike with the expertise needed to develop and optimize metal-ion capacitor technology for various applications.• Provides a clear and accessible overview of the principles underlying metal-ion capacitors based on monovalent and multivalent ions, including their electrochemical mechanisms, materials synthesis, and device architectures• Offers practical guidance on the design, fabrication, and characterization of metal-ion capacitors in both half- and full-cell configurations• Explores the current state-of-the-art in metal-ion capacitor technology, highlighting key innovations, challenges, and opportunities for integration into various industries, such as renewable energy, transportation, and electronics