Immense efforts are being made to develop efficient energy-storage devices to cater to the constantly increasing energy demand due to population growth. Research is being carried out to explore the various aspects of batteries to increase their energy density, charge storage, and stability. This book discusses in detail the important components of battery development, such as electrodes, electrolytes, active materials, and battery construction. It starts with the advantages and limitations of the hallmark lithium-ion batteries, evolving to the introduction of other metal-based batteries such as zinc-, sodium-, metal–air-, and magnesium-based batteries. It specifically reviews lithium–sulfur batteries, which can produce high energy densities. It subsequently discusses the physics behind the transport dynamics of solid-state polymer electrolytes. It includes redox-active materials, mainly polymers and organic molecules, for further understanding and expanding the options of battery development. It finally analyzes the high dependence of the current technology of batteries on the combination of battery design aspects and renewable electricity sources, which has resulted in regenerative flow batteries. With chapters written by experts in the field, the book covers the recent advances that will be of interest to academics and researchers in the fields of energy storage, electrochemistry, materials development, and sustainable chemistry.