In a thin film Li-ion battery, the separator must be a thin and flexible solid. Typically today, this material is a polymer-based material. Since thin film batteries are made of all solid materials, allows one to use simpler separator materials in these systems such as Xerox paper rather than in liquid based Li-ion batteries.
(Royal Society of Chemistry) A review. Poly (vinylidene fluoride), PVDF, and its copolymers exhibit interesting properties for use as separator membranes in lithium-ion battery applications. This review presents the developments and summarizes the main characteristics of these materials for battery separator membranes.
The concept of thin-film lithium-ion batteries was increasingly motivated by manufacturing advantages presented by the polymer technology for their use as electrolytes. LiPON, lithium phosphorus oxynitride, is an amorphous glassy material used as an electrolyte material in thin film flexible batteries.
The separator is a crit. component of lithium-ion batteries since it provides a phys. barrier between the pos. and neg. electrodes in order to prevent elec. short circuits. The separator also serves as the electrolyte reservoir for the transport of ions during the charging and discharging cycles of a battery.
Thin separators with robust mechanical strength are undoubtedly prime choice to make lithium-based batteries more reliable and safer. Recently, great accomplishments have been achieved for advanced thin separators used in LIBs and a detailed discussion is following in this section. 5.1. Functionalized polyolefin separators
However, such thick separators come at the expense of less free space for accommodating active materials inside the battery, thus impeding further development of next-generation lithium-based batteries with high energy density.