Mechanical-Electrochemical Modeling of Agglomerate Particles in Lithium-Ion Battery Electrodes
Mechanical-Electrochemical Modeling of Agglomerate Particles in Lithium-Ion Battery Electrodes
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DOI：
10.1149/2.1331614jes
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发表时间：
2016
影响因子：
3.9
通讯作者：
Bin Wu;W. Lu
中科院分区：
文献类型：
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作者：
Bin Wu;W. Lu
用于锂离子电池应用的许多电极材料由二次颗粒组成。这种活性物质颗粒不是固体颗粒，而是由许多细小的初级颗粒组成。本文提出了一个力学和电化学耦合的模型来预测具有团聚结构的二次粒子中的插层诱导应力。在这个模型中的电化学和运输过程占在二次和一次粒子水平。对于力学分析，二次粒子被视为一个连续体，通过锂浓度和弹性变形计算应力。利用这个模型，我们揭示了影响次级粒子应力的几个重要因素。我们的模拟表明，活性材料的开路电位对锂离子浓度的更强的依赖性降低了应力水平。次级粒子表面的过电位越大，应力就越大。较大的初级颗粒尺寸有助于减小次级颗粒中的应力，只要次级颗粒是包含许多初级颗粒的连续体。最后，多孔二次颗粒和相同尺寸的固体颗粒之间的比较表明，多孔二次颗粒中的应力水平小得多。
Many electrode materials for lithium-ion battery applications are composed of secondary particles. Such an active material particle is not a solid particle, but consists of many fine primary particles. This work presents a coupled mechanical and electrochemical model to predict the intercalation-induced stress in a secondary particle with an agglomerate structure. In this model the electrochemical and transport processes are accounted for at both the secondary and primary particle levels. For mechanical analysis the secondary particle is treated as a continuum with stress calculated through lithium concentration and elastic deformation. With this model we revealed several important factors that affect stresses in secondary particles. Our simulations show that a stronger dependence of the open circuit potential of the active material on lithium-ion concentration reduces the stress level. A larger magnitude of over-potential at the surface of a secondary particle causes larger stresses. A larger primary particle size helps to reduce the stresses in the secondary particle as long as the secondary particle is a continuum containing many primary particles. Finally, a comparison between a porous secondary particle and a solid particle of the same size shows that the stress level in a porous secondary particle is much smaller.