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 ClO4- ions through the coupling of PVP and ClO4- 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 ClO4- ions, which reduced the crystallinity of PEO by steric hindrance, segregated from the PEO by the coupling of PVP and ClO4- 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.