快离子在和离子电池的框架能源材料中的表面式扩散
Jingxi Zhang1, Yanhao Dong1, Chang-An Wang1
1State Key Lab of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, 100084, Beijing, China.
Angewandte Chemie (International ed. in English)
|June 4, 2024
概括
电池中的高离子导电性源于一种独特的类似表面的离子扩散机制,而不是传统的晶格扩散. 优化通道大小可以增强这种表面扩散,从而提高电池性能.
科学领域:
- 材料科学 材料科学 材料科学
- 电化学 电化学 电化学
- 固态化学 固态化学
背景情况:
- 电化学设备的性能受到电解质和电极中的离子导电能力的限制.
- 像普鲁士蓝色类似物 (用于离子) 和氧化物 (用于离子) 这样的高速电极表现出无法解释的高离子运输.
- 传统的固态扩散理论无法解释这些材料中观察到的低激活能量和异常的预暴露因子.
研究的目的:
- 阐明特定电极材料中异常高的固态 (Na+) 和 (Li+) 离子运输背后的基本机制.
- 挑战传统的格子扩散模型,并提出一种替代的扩散途径.
- 确定影响离子传输的因素,并为设计高性能电池材料提供见解.
主要方法:
- 密度功能理论 (DFT) 的计算被用来研究离子扩散机制.
- 模拟分析了离子迁移路径,激活能量和前指数因子.
- 进行了格子扩散和拟议的类似表面的扩散机制之间的比较.
- 研究了离子大小,通道尺寸,缺陷和水晶水的影响.
主要成果:
- 一种新型的表面式扩散机制,与传统的格子扩散不同,被确定为高离子导电性的起源.
- 在表面式扩散中,离子沿着具有低协调数和迁移障碍的通道壁迁移.
- 从格子扩散到表面扩散的过渡是由离子和扩散通道之间的尺寸匹配决定的.
- 优化通道大小可以最大限度地降低迁移能量障碍,类似于分子中的气体扩散.
结论:
- 像普鲁士蓝色类似物和氧化物等材料的优越速率性能归因于这种类似表面的扩散机制.
- 了解和控制这种机制,包括缺陷和水晶等因素,对于开发先进的和离子电池至关重要.
- 这些发现为固态离子传输提供了新的视角,并为未来的材料设计提供了指导方针.
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