在固体电解质中直接计算离子运输的相间阶段
Siqi Shi1, Peng Lu, Zhongyi Liu
1School of Engineering, Brown University, Providence, Rhode Island 02912, USA.
Journal of the American Chemical Society
|August 23, 2012
概括
了解固体电解质相间膜 (SEI) 中的离子运输至关重要. 这项研究揭示了在SEI层内的晶体Li(2) CO(3) 中通过敲除机制进行Li(+) 运输.
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
- 计算化学计算化学
背景情况:
- 固体电解质间相 (SEI) 对于离子电池的性能和寿命至关重要.
- 通过SEI运输Li(+) 的精确机制仍然不太清楚.
- 典型的SEI薄膜包括多孔的有机外层和密集的无机内层.
研究的目的:
- 通过使用多尺度理论方法来阐明SEI膜内Li(+) 传输的机制.
- 为了研究Li(+) 在晶体Li(2) CO(3) 中的扩散,它是SEI内部层的主要组成部分.
- 在SEI层中开发Li(+) 运输属性的预测模型.
主要方法:
- 开发一个多尺度理论方法,结合第一原理计算和中尺度扩散方程.
- 使用密度函数理论 (DFT) 来确定Li(2) CO(3) 中的主导扩散载体和机制.
- 通过实验数据制定一个两层/两机制的扩散模型 (孔隙扩散和敲击扩散).
主要成果:
- 密度函数理论确定了过多的间歇性Li(+) 作为Li(2) CO(3) 中的主导扩散载体.
- 一个"敲开"的扩散机制,保持O-协调,被确定比直接跳跃更为普遍.
- 多尺度模型准确地预测了在SEI层中测量的同位素比率概况,而没有合适的参数.
结论:
- 这项研究阐明了在SEI层内的晶体Li(2) CO(3) 中Li(+) 运输的原子尺度机制.
- 一个新的多尺度模型成功地描述了跨不同SEI层和机制的Li(+) 运输.
- 该方法为预测SEI运输特性和了解电池衰老提供了一个框架.
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