Ionic liquid dispersed Li+ ion oxide glasses and glass-ceramics: Assessment of electrical transport and thermal stability

• Ionic liquid dispersion effect in Li+ ion oxide glasses is studied.
• Ionic liquid addition enhances the conductivity by 2–4 orders of magnitude.
• Ionic liquid-glass composites are predominately ionic in nature.
• A possible qualitative model for electrical transport is suggested.

Effect of ionic liquid (BMIM BF4) dispersion on Li+ ion oxide glass and glass-ceramics has been investigated. Addition of ionic liquid in a very small amount (0.5–5 wt.%) enhances the ionic conductivity significantly. For a typical glass composition 60Li2SO4-40(0.5Li2O–0.5P2O5), with grain size of ~ 50 nm, dispersion of ~ 5 wt.% ionic liquid leads to a conductivity rise of ~ 2–4 orders of magnitude. Structure of ionic liquid dispersed glass and glass-ceramic composites has been investigated by X-ray diffraction and FE-SEM, and thermal properties by DSC. It has been revealed by a galvanic cell method, impedance spectroscopy and dc polarization technique that these composites are essentially ionic in nature. Based on these investigations, a model for electrical transport has been proposed according to which Li+ ions are the majority charge carriers in these composites. The model suggests that ionic liquid acts like a filler between the glass/glass-ceramic grains and Li+ ions mainly migrate through these channels. These composites appear promising for Li+ ion battery applications.