Structural, thermal, and electrochemical studies of biodegradable gel polymer electrolyte for electric double layer capacitor

A quasi-solid-state supercapacitor is fabricated using a biodegradable gel polymer electrolyte (GPE), and graphene nano-platelets (GNPs) capacitive electrodes. The GPE film comprises biodegradable polymer cellulose acetate (CA), ionic liquid, 1-ethyl-3-methylimidazolium thiocyanate (EMImSCN) and dopant salt potassium thiocyanate (KSCN). The polymeric gel films are prepared using the standard “solution cast technique” and characterized by using X-ray diffraction (XRD), Differential scanning calorimetry (DSC), Thermogravemetric analysis (TGA), Impedance spectroscopy, and Linear sweep voltammetry techniques. The synthesized GPE exhibits maximum room temperature ionic conductivity ∼1.2 x 10 −3 S cm −1 and an electrochemical stability window of ∼2.4 V. The electrical double layer capacitor (EDLC) is configured by sandwiching the GPE film between two graphene nanoplatelets (GNPs) electrodes. The performance of the EDLC cell is evaluated in terms of specific capacitance, rate, and pulse power by using cyclic voltammetry, and electrochemical impedance measurement techniques.