ICCM Conferences, The 13th International Conference on Computational Methods (ICCM2022)

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Stress evolution and failure models in elastic-plastic electrodes during electrochemical-mechanical coupling
Jici Wen

Last modified: 2022-06-23

Abstract


High charge capacity anode materials like Si and Sn have attracted great interests in recent years. However, huge volume expansion and contraction in anode materials during charging and discharging lead to high internal stresses and, thus, poor cycle life of high capacity anode batteries. In order to understand the electrochemical-mechanical processes of the electrode material during charging and discharging, stresses in thin film electrodes have be measured by monitoring the bending of the electrode-substrate bilayer and using the Stoney equation. However, the validity of the above equation is contingent when the electrode experiences huge volume changes, large plastic deformation and interfacial failure. Hence we developed a robust electrochemical-mechanical coupled numerical procedure and identify how the constitutive behavior of electrode materials and film-substrate interfacial properties affect the measured stress-capacity curves of electrodes, and hence establish the relationship of electrode material parameters with the characteristics of stress-capacity curves. Also we develop anisotropic expansion models for silicon nanotubes with different crystal structures. Our results show that the fracture ratios of silicon nanotubes are tightly related to maximum hoop stress concentration, which is caused by anisotropic expansion properties in different crystal structures.