Effect of NaClO4 Dopant on Chemical Bond and Electrochemical Characteristic of Benzoyl Kappa-Carrageenan Gel Biopolymer Electrolyte

Abstract

Gel biopolymer electrolytes based on benzoyl kappa-carrageenan (Bz-κcar) as polymer host and sodium perchlorate (NaClO₄) as dopants are successfully produced. The concentration of NaClO₄ is varied from 0.5 to 3.0 wt% to investigate its effects on the chemical bonds and electrochemical characteristic of electrolytes. Characterizations are performed by Fourier-transform infrared spectroscopy (FTIR) and electrochemical impedance analysis (EIS), linear sweep voltammetry, and transference number measurement. Significant changes in the FTIR spectra are detected, which indicate chemical interactions between Bz-ƙcar and NaClO₄. The ionic conductivity (σ) of the gel electrolytes increases with higher concentrations of NaClO₄, suggesting that NaClO₄ is an effective charge carrier in the system. The highest σ of the gel electrolyte attained at ambient temperature is 1.29 × 10⁻³ S cm⁻¹. The temperature dependence of conductivity is Arrhenian in the studied temperature range and achieves an elevated σ of 7.90 × 10⁻³ S cm⁻¹ at 373 K with small values in the activation energy (E_a) observed in all the prepared electrolytes. Electrochemical stability of 1.50 V achieves the highest conducting electrolyte by means of linear sweep voltammetry. Transference number measurement confirms that ions predominate the conduction of electrolyte with 0.85 ion transference number.