Polymer Electrolyte is an ion carrier that can be formed into large-area thin films, which lower internal cell resistance even for electrolytes with moderate conductivity. They function as an electron separator electrochemically compatible with highly reactive anodes and cathodes. It is a binder of cathode active material and also serves as a separator. This electrolyte is also used as model materials for the investigation of conduction paths in semi crystalline systems. Operation of the battery at higher temperatures also leads to an improved conductivity of the polymer electrolyte. They are also less reactive with respect to lithium, which is beneficial for the safety of the battery. The use of an electrolyte offers the possibility of fast production of the cells using web equipment and the fabrication of thin cells.