Recent advances in electrochemistry and materials science have opened the way to the evolution of entirely new types of energy storage systems: rechargeable lithium-ion batteries, electrochroms, hydrogen containers, etc., all of which have greatly improved electrical performance and other desirable characteristics. This book encompasses all the disciplines linked in the progress from fundamentals to applications, from description and modelling of different materials to technological use, from general diagnostics to methods related to technological control and operation of intercalation compounds. Designing devices with higher specific energy and power will require a more profound understanding of material properties and performance. This book covers the status of materials and advanced activities based on the development of new substances for energy storage.