Fabrication of high-performance symmetrical supercapacitor using lithium iodide-based biopolymer electrolyte

Lithium iodide-incorporated solid polymer electrolyte has been developed by using the optimized blend of iota carrageenan and acacia gum with ethylene glycol as a plasticizer using the solution cast technique. Structural studies have been done by using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analysis. The thermal stability of the polymer blend electrolytes is analyzed by using differential scanning calorimetry (DSC). The conductivity of the blend electrolytes was measured by using an impedance analyzer. Among them, the one with 15 wt% LiI incorporated polymer electrolyte (referred to as IAI15) exhibits the higher conductivity as 1.21 × 10 −3 S cm −1 . It also has a low activation energy of 0.05 eV and a high ionic transport number of 0.999. The frequency dependence of the dielectric parameters and the dielectric loss tangent are used to confirm the non-Debye property of the prepared polymer electrolytes. Furthermore, the specific electrolyte (IAI15) is utilized in the fabrication of a symmetric capacitor. Remarkably, the cyclic voltammetry (CV) response shows no redox peaks across its entire potential range, indicating electric double-layer capacitor (EDLC) behavior. Through galvanostatic charge/discharge (GCD) studies on a prepared symmetrical capacitor, discharge time and specific capacitance ( C s ) values are determined as 30 s and 150 F/g, respectively.