Separator Materials Influence on Supercapacitors Performance in Viscous Electrolytes

Abstract

Influence of separator material on the high and low frequency series resistance, characteristic time constant, energy and power densities of the supercapacitors (SCs), based on two identical ideally polarizable microporous titanium carbide-derived carbon electrodes in different electrolytes: 1M (C2H5)3CH3NBF4 in acetonitrile (AN) solution, 1M (C2H5)3CH3NBF4 in dimethyl carbonate, ethylene carbonate and propylene carbonate (DMC:EC:PC) mixture, and 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid, has been tested by cyclic voltammetry, electrochemical impedance spectroscopy, and constant power discharge methods. Four different separator materials were studied, two commercial ones TF4425 and Celgard2400, and two self-made PVDF membranes with different morphologies. Influence of temperature on the SC characteristics has been performed at +24 and -30 °C with SCs completed with 1M (C2H5)3CH3NBF4 in AN and in DMC:EC:PC electrolytes. It was established that the separator material structure and chemical composition noticeably influences the high frequency series resistance, phase angle, characteristic time constant and power density values of SC.

Advances in materials and fabrication of separators in supercapacitors

“…The influence of the wettability of the separator and the material with which it is fabricated on the SC performance was highlighted by Liivand et al 192 SCs were fabricated using four different separators (two commercial ones made from cellulose and polypropylene (Celgard 2400) and two self-made separators fabricated by electrospinning PVDF with varying surface morphologies) in three different electrolytes. At low temperatures and high scan rates, a poorly wetted separator limited the capacitive behaviour.…”

Review—An Overview on Supercapacitors and Its Applications

“…Separators are also expected to keep adverse materials such as gases, air and humidity, away from the internal atmosphere of the device. 103,104 The separators commonly used are fiber glass textiles, natural collagen from egg shells, cellulose and polymers.…”

Synthesis of PVA/SiO2 Nanofibers by Electrospinning Method for Supercapacitor Separators

“…Supercapacitors, also known as double-layer electric capacitors and ultracapacitors, are energy storage devices with short charging and usage times and high electrical efficiency (up to 98%), high power density and excellent cycle capability (can be refilled to more than 106 times) [2]. The main components of supercapacitors are electrodes, separators, collector and electrolyte currents and supercapacitors can store energy in the form of electrostatic charge accumulation at the electrode/electrolyte interface.…”