Uniform thin film based polymer separators for rechargeable Li-ion batteries

Abstract

Battery separator’s main function is to prevent physical contact of the electrodes while permitting ions to flow freely. They itself does not participate in any cell reactions, however, its properties significantly determine the performance and safety of the batteries. For high energy and power densities, the separator is required to be very thin and highly porous, while it adversely affects the safety and cycle life of the battery as a result of the reduced mechanical strength. The safety requirement is a top priority for rechargeable Li-ion batteries, especially these used in hybrid electric vehicles and power tools. Battery separators need to have excellent porosity, as well as low cost, lightness and durability.