The present book entitled PVP based polymer electrolyte films for solid state battery applications deals with the investigations on structural, electrical, optical properties and electro chemical cell applications. During the last four decades, solid state ions has emerged as one of the major interdisciplinary fields of physics, chemistry, material science, engineering and technology. It deals with ionic solids, which exhibit high ionic conductivity is called super ionic conductors or fast ion conductors. These are also called as solid electrolytes, since they exhibit ionic conductivity comparable to that of liquid electrolytes. The study of these materials has attracted considerable attention in view of their potential application in various electro chemical devices such as solid state batteries, fuel cells, sensors, timers, capacitors, memory devices etc. Based on the micro structure and physical properties, the materials are classified as crystalline / poly crystalline, glasses / amorphous, composites and polymer electrolytes. Among these polymer electrolytes are the materials of current interest due to their relative advantages and special mechanical propertie