SOLID POLYMER ELECTROLYTES BASED ON NANOCOMPOSITES OF POLYETHYLENE OXIDE/SODIUM THIOCYANATE/MONTMORILLONITE

摘要

The rapid development of portable electronic devices and electric/hybrid vehicles has increased the demand for compact, lightweight, high capacity batteries. Considerable efforts have been devoted to the development of solid polymer electrolytes (SPE) with high ionic conductivity (～10~(-4) S/cm) and dimensional stability. Poly(ethylene oxide)/alkali metal salt-based solid electrolytes is the most interest ing base material because of its high chemical and thermal stability. PEO is a semicrystalline polymer, possessing both an amorphous and a crystalline phase at room temperature. It can also solvate a wide variety of salts, even at very high salt concentrations. The solvation of salts occurs through the associat ion of the metallic cations with the oxygen atoms in the backbone. The multi-phase nature of PEO is most often regarded as a major problem in real working systems, since the ionic conduction has been shown to take place mainly in the amorphous phase. Many investigations have been done to reduce the crystalline content, via various approaches such as using blends, copolymers, comb-branch polymers and cross-linked polymer networks. Our interest is to overcome these problems by the incorporation of mineral clay which is an inorganic filler with intercalation property. Intercalating polymer in layered clay host can produce huge interfacial area to sustain the mechanical property of polymer electrolyte system and imparts salt-solvating power to dissolve the lithium salts. In this work, we present polymer electrolyte nanocomposites consisting of (PEO)_8 NaSCN/MMT at various clay (Montmorillonite, MMT) content. Structures, interaction, thermal behavior and ionic conductivity of (PEO)_8 NaSCN/ MMT were studied to clarify the role of clay fillers on properties of these materials.