11. Characteristics of Separator Materials for Supercapacitors

Separator in a supercapacitor is used as a sandwich between two electrodes. The essential functions of separator materials remain the prevention of the device from short circuit, storage of electrolyte into its pores, and passage of ions during charging and discharging processes. Material selection for the separator also plays an important role in deciding the final performance of the supercapacitor devices. Ionic conductivity of the separator affects the power and energy density. For safety purpose, thermal stability of the separator is very important. For the flexible electronic devices, bendable separators of high mechanical strength are needed. Separator should have optimum porosity and high electrolyte uptake such that it can provide adequate electrolyte ions to the electrode. The example of the most commonly used separator is polyolefin materials. This chapter deals with the importance of the separator materials, the governing equations, and essential parameters.