Three-dimensional phase field based finite element study on Li intercalation-induced stress in polycrystalline LiCoO2

Abstract

In this study, the stress generation of LiCoO2 with realistic 3D microstructures has been studied systematically. Phase field method was employed to generate the 3D microstructures with different grain sizes. The effects of grain size, grain crystallographic orientation, and grain boundary diffusivity on chemical diffusion coefficient and stress generation were studied using finite element method. The calculated chemical diffusion coefficient is about in the range of 8.5×10 -10 cm 2 /s to 3.6×10 -9 cm 2 /s. Stresses increase with the increase of grain size, due to more accumulation of Li ion near the grain boundary regions in larger grain size systems, which causes a larger concentration gradient. Failure is more likely to occur in large grain systems. The chemical diffusion coefficients increase with increasing grain orientation angle irrespective of grain boundary diffusivity, due to alignment of global Li ion diffusion path with high grain orientations. Grain boundary diffusivity has opposite effect on the hydrostatic stress. As small grain boundary diffusivity, the stress increases with increasing grain orientation angle, due to

Three-Dimensional Finite Element Study on Li Diffusion Induced Stress in FIB-SEM Reconstructed LiCoO2 Half Cell

“…It is shown that the ideal solution thermodynamics assumption was applied in describing the transport of lithium ions and diffusion induced stress, and is widely used in battery modeling [12][13][14][21][22][23]. Hence, the transport of Lithium ions in active particles is described by the modified Fick's law [12,24], which includes the effect of stress on diffusion:…”

Three-dimensional finite element study on stress generation in synchrotron X-ray tomography reconstructed nickel-manganese-cobalt based half cell

“…One of the critical challenges of LIBs is to enhance the mechanical stability of electrode materials. Diffusion induced stresses [8,9] and phase transition [10,11] during the operations of LIBs can cause fracture and mechanical failure. Hence, it is important to understand the stress generation in battery materials.…”

“…Many studies have been done to study the stress generation to prevent the mechanical failures of LIBs [9,[12][13][14][15][16]. Zhang et al [14,15] studied the diffusion induced stresses in LiMn2O4 under galvanostatic and potentiodynamic conditions using ellipsoid shaped particle model.…”

“…To take into accounts for this phenomenon, different components of strain where the maximum von Mises stresses occur were calculated. The total strain consists of intercalation strain, phase transition strain and mechanical strain, as illustrated in equation (9). As shown in Fig.…”

Three-Dimensional Finite Element Study on Lithium Diffusion and Intercalation-Induced Stress in Polycrystalline LiCoO2 Using Anisotropic Material Properties

“…The model doesn't include the stress analysis caused by lithium intercalation. Our previous study [19] showed the effective Li diffusivity and stress generation are strongly affected by grain orientation, grain size and grain boundary diffusivity. In this study, the major contribution is to demonstrate the importance to include anisotropic property in the model.…”