Lithium ion conducting biopolymer membrane based on K-carrageenan with LiNO3

Abstract

Energy crisis and environmental pollution are the major problems faced by all the people at present time. It is time to switch over to biopolymer electrolyte-based batteries instead of synthetic due to its high cost and not being environmentally green. Biopolymer membranes have been prepared using 1 g K-carrageenan with different molar mass percentages of LiNO3 by solution casting technique using double-distilled water as a solvent. Prepared biopolymer electrolyte membranes are characterized by XRD, FTIR, DSC, and AC impedance techniques. XRD confirms the amorphous nature of the biopolymer membranes. FTIR reveals the complexation formed between 1 g K-carrageenan and LiNO3. It has been found from DSC analysis that glass transition temperature of the biopolymer membrane 1 g K-carrageenan with LiNO3 decreases due to the addition of salt compared to the pure biopolymer 1 g K-carrageenan. Biopolymer membrane 1 g K-carrageenan with 0.65 wt% of LiNO3 has got the highest ionic conductivity of 1.89 × 10−3 S cm−1. Transference number analysis has been done by Wagner’s polarization method and Bruce and Vincent method. Electrochemical stability has been studied by linear sweep voltammetry. The highest conducting biopolymer membrane (1 g K-carrageenan with 0.65 wt% of LiNO3) is electrochemically stable up to 3.2 V. Lithium ion conducting battery has been constructed using the highest conducting biopolymer membrane and its performance has been analyzed.