Lithium-sulfur (Li-S) batteries give us an alternative to the more prevalent lithium-ion (Li-ion) versions, and are known for their observed high energy densities. Systems using Li-S batteries are in early stages of development and commercialization however could potentially provide higher, safer levels of energy at significantly lower cost.In this book the history, scientific background, challenges and future perspectives of the lithium-sulfur system are presented by experts in the field. Focus is on past and recent advances of each cell compartment responsible for the performance of the Li-S battery, and includes analysis of characterization tools, new designs and computational modeling. As a comprehensive review of current state-of-play, it is ideal for undergraduates, graduate students, researchers, physicists, chemists and materials scientists interested in energy storage, material science and electrochemistry.