STRUCTURE AND ELECTROCHEMISTRY OF POLYMER ELECTROLYTES
STRUCTURE AND ELECTROCHEMISTRY OF POLYMER ELECTROLYTES
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DOI：
10.1016/0013-4686(95)00144-4
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发表时间：
1995-10-01
影响因子：
6.6
通讯作者：
BRUCE, PG
中科院分区：
文献类型：
--
作者：
BRUCE, PG
重点介绍了聚合物电解质领域中两个重要但常被忽视的问题。第一个是关于结晶聚合物电解质的结构，从中可以学到很多关于一般聚合物电解质结构的原理。讨论了PEO（3）-LiCF_3SO_3、PEO（3）-NaClO_4、PEO（4）-KSCN、PEO（4）-NH_4SCN和PEO（4）-RbSCN的晶体结构。这些表明，与既定的观点，从Li+到Rb+的大小范围内的阳离子被容纳在PEO螺旋，虽然链构象的变化与阳离子的大小增加。阳离子周围的配位数从Li+的情况下的5增加到Rb+的情况下的7。在研究的所有实例中，阳离子周围的直接环境由两种阴离子组成，其余配体是来自PEO链的醚氧。每个离子仅与一个链相关联，因此不存在离子交联。这表明在聚合物电解质体系中链内而不是链间交联的重要性。看来，T-g可能会增加与盐含量，主要是由于链内，而不是链间交联。阳离子的位置内的PEO螺旋在这里报道的所有系统中可能有影响的离子传导机制。第二个被忽视的主题是聚合物电解质的界面电化学，特别是在金属电极上的固体聚合物中的氧化还原反应。我们已经表明，交流光谱和超微电极的组合提供了一个理想的工具，其中研究聚合物电解质中的界面反应。阻抗测量值已达到10（9）Ω。这表明二茂铁在铂电极上的电化学是复杂的，而Fe-3+/2+电对至少在低浓度下表现出简单的一步电极反应。讨论了在固体和液体醚溶剂中氧化还原反应的研究在理解电子转移这一重要课题中所起的关键作用。
Two essential but often neglected topics in the field of polymer electrolytes are highlighted. The first concerns the structure of crystalline polymer electrolytes, from which much may be learnt about the principles governing polymer electrolyte structure in general. The crystal structures of PEO(3)-LiCF3SO3, PEO(3)-NaClO4, PEO(4)-KSCN, PEO(4)-NH4SCN and PEO(4)-RbSCN are discussed. These reveal that, contrary to the established view, cations ranging in size from Li+ to Rb+ are accommodated within the PEO helix, although the chain conformation changes with increasing cation size. The coordination number around the cations increases from 5, in the case of Li+, to 7 in the case of Rb+. In all examples studied, the immediate environment around the cation is composed of two anions with the remaining ligands being ether oxygens From the PEO chain. Each ion is associated with only one chain and thus there is no ionic cross-linking. This suggests the importance of intrachain rather than interchain cross-linking in polymer electrolyte systems. It appears that T-g may increase with salt content due mainly to intrachain rather than interchain cross-links. The location of the cation within the PEO helix in all systems reported here may have implications for the mechanism of ionic conduction. The second much-neglected topic is the interfacial electrochemistry of polymer electrolytes, particularly redox reactions in solid polymers at metal electrodes. We have shown that the combination of ac spectroscopy and ultramicroelectrodes provides an ideal tool with which to study interfacial reactions in polymer electrolytes. Impedance measurements have been made up to 10(9) Omega. These reveal that the electrochemistry of ferrocene on platinum electrodes is complex, whereas the Fe-3+/2+ couple appears, at least at low concentrations, to exhibit a simple one-step electrode reaction. The crucial role that the study of redox reactions in solid and liquid ether solvents can play in understanding the important topic of electron transfer in general is discussed.