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Toward Optimal Performance and In‐Depth Understanding of Spinel Li4Ti5O12 Electrodes through Phase Field Modeling
Advanced Functional Materials ( IF 19.0 ) Pub Date : 2018-02-19 , DOI: 10.1002/adfm.201705992
Alexandros Vasileiadis 1 , Niek J. J. de Klerk 1 , Raymond B. Smith 2 , Swapna Ganapathy 1 , Peter Paul R. M. L. Harks 3 , Martin Z. Bazant 2, 4 , Marnix Wagemaker 1
Affiliation  

Computational modeling is vital for the fundamental understanding of processes in Li‐ion batteries. However, capturing nanoscopic to mesoscopic phase thermodynamics and kinetics in the solid electrode particles embedded in realistic electrode morphologies is challenging. In particular for electrode materials displaying a first order phase transition, such as LiFePO4, graphite, and spinel Li4Ti5O12, predicting the macroscopic electrochemical behavior requires an accurate physical model. Herein, a thermodynamic phase field model is presented for Li‐ion insertion in spinel Li4Ti5O12 which captures the performance limitations presented in literature as a function of all relevant electrode parameters. The phase stability in the model is based on ab initio density functional theory calculations and the Li‐ion diffusion parameters on nanoscopic nuclear magnetic resonance (NMR) measurements of Li‐ion mobility, resulting in a parameter free model. The direct comparison with prepared electrodes shows good agreement over three orders of magnitude in the discharge current. Overpotentials associated with the various charge transport processes, as well as the active particle fraction relevant for local hotspots in batteries, are analyzed. It is demonstrated which process limits the electrode performance under a variety of realistic conditions, providing comprehensive understanding of the nanoscopic to microscopic properties. These results provide concrete directions toward the design of optimally performing Li4Ti5O12 electrodes.

中文翻译:

通过相场建模实现尖晶石Li4Ti5O12电极的最佳性能和深度理解

计算模型对于基本了解锂离子电池过程至关重要。然而,捕获嵌入在现实电极形态中的固体电极颗粒中的纳米到介观相的热力学和动力学是具有挑战性的。特别是对于显示一阶相变的电极材料(例如LiFePO 4,石墨和尖晶石Li 4 Ti 5 O 12),预测宏观电化学行为需要准确的物理模型。在此,提出了一种用于在尖晶石Li 4 Ti 5 O 12中插入锂离子的热力学相场模型。它捕获了文献中作为所有相关电极参数函数的性能限制。该模型中的相稳定性基于从头算密度函数理论计算和锂离子迁移率的纳米核磁共振(NMR)测量结果中的锂离子扩散参数,从而形成了无参数模型。与准备好的电极的直接比较表明,在放电电流的三个数量级上都具有良好的一致性。分析了与各种电荷传输过程有关的超电势,以及与电池局部热点有关的活性粒子分数。它被证明限制了在各种实际条件下的电极性能的过程,从而提供了从纳米到微观特性的全面理解。4 Ti 5 O 12电极。
更新日期:2018-02-19
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