The field of solid state ionics is enjoying significant activity due to several major breakthroughs in the materials aspects of rechargeable batteries, supercapacitors, sensors, electrochromics, catalysis and ion exchange materials. Solid state chemistry and physics, materials science and electrochemistry are the main contributors to these efforts. Material designers, for example, have been able to synthesize materials with desired ionic/electronic properties, tailor surface areas and crystal structures, and design porosities through templating action. Atomic and molecular simulation of large systems are also becoming a reality. This fourth book in the series from MRS offers theoretical, experimental and applied perspectives on the realm of solid state ionics. Emphasis is on the new generation of rechargeable lithium batteries. Topics include: insertion compounds; sol-gel process; theory of ion conduction in solids; defect chemistry; solid electrolytes; polymer electrolytes and electrodes and ionic devices.