Discussion on the influence of DES content in CA-based polymer electrolytes

Abstract

The degree of crystallinity in the matrix formed by cellulose acetate (CA) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) were reduced by embedding with deep eutectic solvent (DES) which is a type of ionic mixture synthesized from choline chloride and urea in a specific ratio. The fabrications of thin films were done by solution casting technique. The sample with composition of CA:LiTFSI:DES (28 wt%:12 wt%:60 wt%) appears as the highest conducting sample with the calculated value of 2.61 × 10−3 S cm−1 at ambient temperature. This high conducting sample possesses low relative viscosity so as to have high ion fluidity of 0.19. SEM micrographs were used to study the structural alternation that took place in the presence of DES at different ratio in the polymer electrolytes matrix. The dielectric loss tangent plot reveals the low relaxation time for high conducting sample which has immense movements of lithium conducting ion (Li+). The enhancement in the ionic conductivity of the DES plasticized samples with temperature obeys Arrhenius rule.