在固体聚合物电解质中,Mg2+,Na+和K+的转移数和离子协调强度
Rassmus Andersson1, Caroline Mönich2, Guiomar Hernández1
1Department of Chemistry, Ångström Laboratory, Uppsala University, Box 538, SE-751 21 Uppsala, Sweden.
概括
确定离子传输效率 (传输数) 对固体聚合物电解质至关重要. 这项研究引入了,和离子的新方法,揭示了它们的电荷传输机制.
科学领域:
- 固态电化学 固态电化学
- 材料科学是一种材料科学.
- 离子运输现象是一种离子运输现象.
背景情况:
- 转移数 (T+) 对固体聚合物电解质性能至关重要,量化离子传输效率.
- 现有的方法不足以理解"超出Li"系统中的离子运输,阻碍了进步.
- 聚合物电解质是下一代电池和电化学设备的关键.
研究的目的:
- 建立和验证一种新的方法,用于确定固体聚合物电解质中的单价和双价的转移数 (T+).
- 研究聚乙烯 (PCL) 中Na+,K+和Mg2+的离子运输机制,并与聚乙烯氧化物 (PEO) 进行比较.
- 阐明聚合物电解质中阴离子协调和转移数之间的关系.
主要方法:
- 电泳核磁共振 (eNMR) 与电化学阻抗光谱学 (EIS) 相结合.
- 将eNMR/EIS结合技术应用于PCL中Na+,K+和Mg2+的应用.
- 对聚乙烯氧化物 (PEO) 系统的现有数据进行比较分析.
主要成果:
- 在所有研究的阳离子中,观察到阳离子协调和低转移数 (T+) 之间存在强烈的相关性.
- 矛盾的是,PCL中的Mg2+与单价离子 (∼0.5) 相比,显示出高的T+ (0.86).
- 在PCL中的Mg2+表现出持续的集群,表现为单价[MgTFSI]+物种,T+为0.43,而实际的Mg2+T+为0.86.
结论:
- 在具有挑战性的多价值聚合物电解质系统中,eNMR/EIS方法为量化离子运输提供了强大的工具.
- 阴离子协调显著影响离子流动性,更强的协调导致更低的转移数.
- 在PCL中Mg2+的独特行为凸显了考虑离子聚合和有效电荷状态对于准确的运输分析的重要性.
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