Basak Pratyay, Manorama Sunkara V, Singh Rajnish K, Parkash Om
Materials Science Group, Inorganic and Physical Chemistry Division, Indian Institute of Chemical Technology, Hyderabad 500 007, India.
J Phys Chem B. 2005 Jan 27;109(3):1174-82. doi: 10.1021/jp0460792.
This paper is a first comprehensive study on the correlated ion transport mechanisms contributing to the overall conductivity behavior in a new class of poly(ethylene oxide)-polyurethane/polyacrylonitrile (PEO-PU/PAN) semi-interpenetrating polymer networks (semi-IPNs)-salt complex polymer electrolytes. A simultaneous investigation of the electrical response on PEO-PU/PAN/LiClO(4) and PEO-PU/PAN/LiCF(3)SO(3) semi-IPNs with varying EO/Li mole ratios (100, 60, 30, 20, 15, 10) has been carried out by impedance spectroscopy. Analysis of the complex plane and spectroscopic plots indicated the presence of two microscopic phases corresponding to the PEO-PU and PAN domains, which leads to space charge polarization in these systems. A suitably modified approach based on the universal power law (UPL) considering the independent contribution from the individual microphases of semi-IPNs facilitates a complete interpretation of the spectroscopic profiles for the real component of conductivity (sigma'(omega)). The sigma'(omega) spectroscopic profiles were fitted with two power law equations, where the frequency region up to approximately 300 kHz is the conductivity profile associated with the PAN phase and beyond this is the superimposed contribution of the PEO-PU phase. Simulated fits using the UPL equation revealed two relaxation times (tau(PEO)(-)(PU), tau(PAN)) related to ionic hopping in the PEO-PU and PAN phases in addition to the conductivity relaxation time (tau(peak)) determined from the Debye peaks. The respective power law exponents (n(PEO)(-)(PU) approximately 0.5-0.8, n(PAN) approximately 1.0-1.6) indicate that though cationic hopping in the softer PEO-PU phase is favored, anionic hopping in the PAN phase contributes significantly to the charge transport processes in these semi-IPNs. Correlation of the experimental results with the simulated fits enable us to distinguish the effects of semi-IPN composition, temperature, morphology, ion-ion, and ion-polymer interactions, which influence the microscopic molecular events, involved in the charge transport in these complex semi-IPN polymer electrolytes.
本文首次对一类新型聚环氧乙烷-聚氨酯/聚丙烯腈（PEO-PU/PAN）半互穿聚合物网络（半互穿网络）-盐复合聚合物电解质中对整体导电行为有贡献的相关离子传输机制进行了全面研究。通过阻抗谱对不同EO/Li摩尔比（100、60、30、20、15、10）的PEO-PU/PAN/LiClO₄和PEO-PU/PAN/LiCF₃SO₃半互穿网络的电响应进行了同步研究。复平面图和光谱图分析表明存在对应于PEO-PU和PAN域的两个微观相，这导致了这些体系中的空间电荷极化。基于通用幂律（UPL）并考虑半互穿网络各个微相独立贡献的适当修正方法有助于完整解释电导率实部（σ'(ω)）的光谱轮廓。σ'(ω)光谱轮廓用两个幂律方程拟合，其中高达约300 kHz的频率区域是与PAN相相关的电导率轮廓，在此之上是PEO-PU相的叠加贡献。使用UPL方程的模拟拟合揭示了除了由德拜峰确定的电导率弛豫时间（τ(peak)）之外，还有与PEO-PU和PAN相中离子跳跃相关的两个弛豫时间（τ(PEO)(-)(PU)，τ(PAN)）。各自的幂律指数（n(PEO)(-)(PU)约为0.5 - 0.8，n(PAN)约为1.0 - 1.6）表明，尽管在较软的PEO-PU相中阳离子跳跃更有利，但PAN相中的阴离子跳跃对这些半互穿网络中的电荷传输过程有显著贡献。实验结果与模拟拟合的相关性使我们能够区分半互穿网络组成、温度、形态、离子-离子和离子-聚合物相互作用的影响，这些影响微观分子事件，参与了这些复杂的半互穿网络聚合物电解质中的电荷传输。
