The fabrication and properties of solid polymer electrolytes based on PEO/PVP blends

New solid polymer electrolytes were fabricated by the addition of lithium perchlorates in the blends of polyethylene oxide (PEO, MW = 5 × 106) and poly-4-vinylpyridine (PVP, MW = 1.6 × 106). Not only the coordinating bonding between ether units (–O–) of PEO and Li+ ions at about 1100 cm−1 but also the existence of pyridine salts at about 3500 cm−1 were definitely observed in the FT-IR spectra. The addition of PVP in the PEO matrix is to restrict mobility of ClO 4 - ions through the coupling of PVP and ClO 4 - ions. Therefore, the increase of PVP content is expected to decrease the self-discharge rate. In the case of PEO–PVP blends without LiClO4, the melting temperature Tm and the degree of crystallinity were decreased by the increase of PVP content. On the contrary, those of PEO–PVP blends with LiClO4 were increased with the increase of PVP content. The results can be explained lay ClO 4 - ions, which reduced the crystallinity of PEO by steric hindrance, segregated from the PEO by the coupling of PVP and ClO 4 - ions. The new solid polymer electrolytes based on PEO–PVP blends showed ionic conductivities of the order of 10−8 to 10−7 S/cm.