A study incorporating nano-sized silica into PVC-blend-based polymer electrolytes for lithium batteries

Blends of poly(vinyl chloride)-poly(methyl methacrylate) (PVC/PMMA) and poly(vinyl chloride)-poly(ethylene oxide) (PVC/PEO) with lithium triflate (LiCF₃SO₃) as salt, ethylene carbonate (EC), and dibuthyl phthalate (DBP) as plasticizers and nano-sized silica (SiO₂) as filler, the first of its kind in such a study, were prepared using the solution-cast technique. This study affirmed that SiO₂ added PVC-PMMA and PVC-PEO-blend-based polymer electrolytes have the ability to retain their ionic conductivity and integrity even after 60 days of storage time at room temperature. The reduction of ionic conductivity values in PVC-PMMA-LiCF₃SO₃-DBP-EC:SiO₂-based and SiO₂-free membranes are 9 and 30%, respectively. When PVC-PEO-blend was used, the reduction of ionic conductivity values in PVC-PEO-LiCF₃SO₃-DBP-EC:SiO₂-based and SiO₂-free system was 16 and 40%, respectively, after 60 days of storage also at room temperature. The SiO₂-based complexes were also found to maintain their conductivity at higher temperatures of 60 °C and 90 °C with progressive storage times. This clearly shows that the SiO₂-induced stabilizing effect is maintained even at higher temperatures. Silica has brought the conductivity of polymer electrolytes into the useful realm for materials in lithium polymer battery applications.