Energy systems are encountered in daily life, whether through smartphones, laptops or cordless tools. Cars using fossil fuels are being replaced with electric and battery powered drives, and storage solutions are being implemented to better integrate renewable energies into the grid. Energy Storage Systems introduces the different storage technologies available today. It begins with mechanical and electrical storage and describes in detail electrochemical storage technologies such as lead and lithium-ion batteries. However, this book aims to explain not only what storage technologies exist but also how these storage technologies are applied in storage systems. Therefore, this book provides a short introduction to requirements management and system engineering to explain how storage systems are designed. Furthermore, the book explains the most important power conversion techniques. The technologies presented are applied in many application examples throughout the book and range from solar power storage systems to battery supported mobile phone masts and commercial vehicles equipped with a hybrid drive system.