超支化聚氨酯固体电解质导电性能的光谱学研究

SPECTROSCOPIC STUDIES ON CONDUCTIVITY OF HYPERBRANCHED POLYURETHANE ELECTROLYTES

用超支化聚氨酯 +线性聚氨酯作为基体 ,LiClO4作为离子源制得聚合物固体电解质 .用Raman光谱 ,FTIR光谱等光谱学方法研究了聚合物电解质中盐离子和聚合物基团之间的相互作用 .研究表明超支化聚氨酯对盐有较好的溶解作用 .

Polymer electrolytes were prepared with hyperbranched polyurethane and linear polyurethane as the host polymer and LiClO4 as the ion source. FTIR spectra was used to analyze the bonding degree of Li+ with carbonyl and ether groups. It was found that Li+ preferred bonding with the ether group, and bonded with the carbonyl group when the salt concentration reached a certain level. The bonding degree of Li+ with ether groups and the carbonyl groups both reached a saturated state at a salt, concentration of EO/Li+ = 4. Raman spectra was applied to analyze the aggregation degree of anions ClO4. The fraction of contact-ion pairs increased with increasing salt concentration. When the salt concentration increased to EO/Li+ = 4, the salt aggregates appeared, but the area fraction of aggregates was merely 1.2%. This indicated that the hyperbranched polyurethane could function as a 'solvent' for the lithium salt. Conductivity analysis indicated that the conductivity kept increasing with increasing concentration of HPU and the conductivity maximum of the present system appeared at a higher salt concentration (EO/Li+ = 4) which could be attributed to the high solvating capability of the hyperbranched polymer. The ionic conductivity of all samples was apparently enhanced with increasing temperature, and the Arrhenius phenomenological relationship could be used to describe the conductivity behavior.