Zuo Peng, Zhao Ya-Pu
State Key Laboratory of Nonlinear Mechanics (LNM), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China.
Phys Chem Chem Phys. 2015 Jan 7;17(1):287-97. doi: 10.1039/c4cp00563e.
Cracking and fracture of electrodes under diffusion during lithiation and delithiation is one of the main factors responsible for short life span of lithium based batteries employing high capacity electrodes. Coupling effects among lithium diffusion, stress evolution and crack propagation have a significant effect on dynamic processes of electrodes during cycling. In this paper, a phase field model coupling lithium diffusion and stress evolution with crack propagation is established. Then the model is applied to a silicon thin film electrode to explore the coupling effects on diffusion and crack propagation paths. During lithiation, simulation results show that lithium accumulates at crack tips and the lithium accumulation further reduces the local hydrostatic stress. Single and multiple crack geometries are considered to elucidate some of the crack patterns in thin film electrodes as a consequence of coupling effects and crack interactions.
在锂化和脱锂过程中，扩散作用下电极的开裂和断裂是导致采用高容量电极的锂基电池寿命较短的主要因素之一。锂扩散、应力演化和裂纹扩展之间的耦合效应，对电极在循环过程中的动态过程有显著影响。本文建立了一个将锂扩散、应力演化与裂纹扩展相耦合的相场模型。然后将该模型应用于硅薄膜电极，以探究其对扩散和裂纹扩展路径的耦合效应。锂化过程中，模拟结果表明锂在裂纹尖端聚集，而锂的聚集进一步降低了局部静水应力。考虑了单裂纹和多裂纹几何形状，以阐明耦合效应和裂纹相互作用导致的薄膜电极中的一些裂纹模式。
