Electrical and structural studies of a LiBOB-based gel polymer electrolyte

• Published in: Ionics 2017-10, Vol.23 (10), p.2669-2675
• Main Authors: Gunathilaka, A. M. I. E., Bandara, L. R. A. K., Arof, A. K., Careem, M. A., Seneviratne, V. A.
• Format: Article
• Language: English
• Subjects: Breathing; Chemistry; Chemistry and Materials Science; Condensed Matter Physics; Deformation; Electrical resistivity; Electrochemistry; Electrolytes; Energy Storage; Ethylene oxide; Fourier transforms; Infrared spectra; Ion currents; Lithium; Optical and Electronic Materials; Original Paper; Polymers; Propylene; Renewable and Green Energy; Stretching
• ISSN: 0947-7047; 1862-0760
• DOI: 10.1007/s11581-016-1834-7

A series of gel polymer electrolytes (GPEs) containing lithium bis(oxalato)borate (LiBOB), propylene carbonate (PC), and ethylene carbonate (EC) have been investigated. Poly(ethylene oxide) (PEO) was used as the polymer. First, a series of liquid electrolytes was prepared by varying the Li:O ratio and obtained the best composition giving the highest conductivity of 7.1 × 10 −3  S cm −1 at room temperature. Then, the PEO-based GPEs were prepared by adding different amounts of LiBOB and PEO into a mixture of equal weights of EC and PC (40 % of each from the total weight). The gel electrolyte comprises of 12.5 % of LiBOB, 7.5 % of PEO, 40 % of EC, and 40 % of PC gave the highest ionic conductivity of 5.8 × 10 −3  S cm −1 at room temperature. From the DC polarization measurements, ionic nature of the gel electrolyte was confirmed. Fourier transform infrared (FTIR) spectra of electrolytes showed the Li + ion coordination with EC and PC molecules. These interactions were exhibited in the peaks corresponding to ring breathing of EC at 893 cm −1 and ring bending of EC and symmetric ring deformation of PC at 712 and 716 cm −1 respectively. The presence of free Li + ions and ion aggregates is evident in the peaks due to the symmetric stretching of O–B–O at 985 cm −1 .