Biodegradable polymer membrane K.sup.+ ion conductor for electrochemical device application

Solid polymer electrolyte (SPE) can prevent electrolyte leakage in double layer electrochemical capacitors (EDLCs). However, the limited ionic conductivity of SPE limits its practical applicability. The fabrication of plasticized SPE with a suitable plasticizer is an effective approach to boost the conductivity of the prepared electrolyte based on eco-friendly polymers, resulting in a high-performance polymer-based EDLC. In this work, chitosan (CS)-polyvinyl alcohol (PVA) blended polymers along with the potassium iodide (KI) dopant salt were selected for the electrolyte preparation. Five samples with varying quantities of glycerol (Gly) plasticizer have been prepared, and the membranes have been evaluated using electrochemical impedance spectroscopy (EIS), which reveals the conductivity characteristics of the electrolyte. The improvement in dielectric properties upon increasing Gly content was explored using EIS data. Through the use of Fourier transform infrared (FTIR) technology, the nature of electrolyte composition and the interaction between various constituents of electrolytes were investigated. The role of plasticizer in improving the ionic conductivity is evident from enhancing both the diffusion coefficient (D) and carrier mobility ([micro]). The transference number measurement (TNM) and linear sweep voltammetry (LSV) techniques have shown that the highest conducting electrolytes are suitable both in terms of potential stability and ionic transference number for electrical double layer capacitor (EDLC) device application with recorded values of 0.9375 and 2.50 V, respectively. The cyclic voltammetry (CV) pattern of the constructed EDLC using the sample with 50 wt.% of Gly as an electrolyte has shown a leaf-like shape without redox reaction, revealing the capacitive nature of the EDLC. The recorded specific capacitance value of 45.91 F g.sup.-1 at 10 mV/s scan rate for the constructed EDLC highlights the success of the prepared polymer-based electrolyte as a mediator in electrochemical device applications.