Coupled effects of charge-discharge cycles and rates on the mechanical behavior of electrodes in lithium-ion batteries

摘要

Understanding the effects of charge rates and cycling time on the mechanical performance of electrodes is crucial for the battery suffered from mechanical abusive loadings. In this study, 18650 lithium-ion cells are cycled at high charging rates of 1, 2 and 3 C for 100 cycles. In addition, others are cycled at 2 C for various cycles (50, 100, 200, and 500). The tensile and compressive behaviors of anodes and cathodes in different states are investigated. Subsequently, the failure mechanisms of mechanical behavior are discussed based on the analysis of X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. Experiments indicate that the tensile properties of anodes after more cycles at higher charging rate become weak significantly, but the corresponding compressive properties tend to be improved in a small extent. Comparatively, a same trend is also represented in the cathodes but is not as significant as anodes. Distinct deformation mechanisms of cathode and anode coatings are found. The coatings with thicker lithium-ion depositions are liable to fall off from Cu foil while no interfacial slip occurs in the cathode. However, the porous depositions improve the compressive properties of electrodes after cycling procedure.