In developing electrochemical cells, one must keep in mind that the real goal is to package and control all the materials and components (cathode and anode active materials, electrolytes, separators, current collectors etc.) in a limited volume to enable maximum energy storage without creating any safety problems. In this manner, Li-Ion batteries (LIB) were first introduced to practical use in 1991. This book contains an in-depth review of electrode materials, electrolytes and additives for LIB, as well as indicators of the future directions for continued maturation of the LIB.