  In this review, latest updates in the poly (ethylene oxide) based
electrolytes are summarized. The ultimate goal of researchers globally is
towards the development of free standing solid polymeric separator for energy
storage devices. This single free standing solid polymeric separator may
replace the liquid and separator (organic/Inorganic) used in existing
efficient/smart energy technology. As an example polyethylene oxide (PEO)
consist of an electron donor rich group which provides coordinating sites to
the cation for migration. Owing to this exclusive structure PEO exhibits some
remarkable properties such as; low glass transition temperature, excellent
flexibility and ability to make complexation with various metal salts which are
unattainable by another polymer host. Hence, the PEO is the most emerging
candidate that have been examined or is currently under audition for
application in energy storage devices. So, this review article first provides
the detailed study of the PEO properties, characteristic of constituents of the
polymer electrolyte and suitable approaches for the modification of polymer
electrolytes. Then, the synthesization and characterizations techniques are
outlined. The structures, characteristics, and performance during
charge-discharge of four types of electrolyte/separators which are Liquid,
Plasticized, and dispersed/intercalated electrolyte are highlighted. The
suitable ion transport mechanism proposed by researchers in the different
renowned group have been discussed for better understanding of the ion dynamics
in such systems.
