A novel configuration of electrical double layer capacitor with plastic crystal based gel polymer electrolyte and graphene nano-platelets as electrodes: A high rate performance

A new, symmetrical, high rate, solid-state EDLC (electrical double layer capacitor) has been fabricated employing a plastic crystal SN (succinonitrile) based GPE (gel polymer electrolyte) and GNPs (graphene nano-platelets) as electrodes. The free-standing GPE film containing poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) exhibits the excellent suitability as electrolyte in EDLC due to its high ionic conductivity (similar to 2 x 10(-3) S cm(-1) at 20 degrees C), thermal stability (from -30 to 80 degrees C), electrochemical stability window (similar to 3.5 V vs. Ag), and excellent mechanical properties. The high rate capability of the EDLC has been observed from the impedance analysis in terms of high knee frequency (similar to 58 Hz), low response time (similar to 791 ms) and high pulse power (similar to 16.4 kW kg(-1)). The cyclic voltammetric response indicates the capacitive performance up to a substantially high scan rate of 1000 mV s(-1), which further confirms the high rate performance of the EDLC. Though the specific energy of the solid-state EDLC is observed to be low (Emax similar to 8.2 Wh kg(-1)), its power density is substantially high (Pmax > 4 kW kg(-1)). After similar to 20% decrement in specific capacitance during the initial charge-discharge cycles, the EDLC offers almost stable performance up to similar to 3500 cycles. (C) 2014 Elsevier Ltd. All rights reserved.