Lithium-ion conducting seaweed and gum-based biopolymer electrolyte for supercapacitor applications

Abstract

Lithium-ion conducting solid polymer electrolytes are prepared by incorporating lithium triflate (LiCF₃SO₃) salt into a plasticized blend of Iota-carrageenan and acacia gum, using the solution casting method. The structural and molecular complexations of the resulting electrolytes are analyzed through X-ray diffraction and Fourier-transform infrared analysis. AC impedance analysis spectra demonstrate that the addition of 33 wt.% of LiCF₃SO₃ salt into the polymer electrolyte blend (IATF50) results in higher ionic conductivity of 3.18 × 10⁻³ S/cm, and a minimum activation energy of 0.03 eV. The highly conductive electrolyte follows the overlapping-large polaron tunnelling (OLPT) paradigm. The dielectric and modulus spectra further confirm the non-Debye nature of the electrolyte. From the transference number measurement, it is confirmed that the conductivity is mostly due to Li ions and the IATF50 sample is chosen to fabricate a symmetrical supercapacitor. Galvanostatic charge/discharge studies show the discharge characteristics with a duration of 30 s and a specific capacitance (C_s) value of 100 F/g.