Effects of ionic liquids and silica nanoparticles on the ionic conductivities, mechanical properties, and rheological properties of sodium-containing solid polymer electrolytes

We fabricate sodium-containing solid polymer electrolytes (SPEs) using an environment-friendly process. We investigate the effects of ionic liquids (ILs) and silica nanoparticles (SiNPs) on the ionic conductivities and mechanical properties of SPEs, and the rheological properties of the suspensions used to make SPEs. ILs are found to act as plasticizers and charge carriers. ILs increase ionic conductivity, but to the detriment of mechanical properties. Ionic conductivity exhibits two maximum peaks at fixed IL concentration with increasing SiNP concentrations. However, unlike ILs, SiNPs have no significant effect on ionic conductivity. The suspensions used to make SPEs exhibit two different non-Newtonian behaviors, shear thinning and yield stress behavior, which depended on IL and SiNP concentrations. It is due to different SiNP dispersities in these suspensions. Furthermore, non-Newtonian behavior is found to be related to processability.