Generation of Realistic Particle Structures and Simulations of Internal Stress: A Numerical/AFM Study of LiMn2O4 Particles

Abstract

In this paper, the real geometries of cathode particles are reconstructed using atomic force microscopy (AFM). Finite element analysis of intercalation-induced stress is applied to the reconstructed realistic geometries of single and aggregated particles. The reconstructed particle geometry shows rugged surfaces at the boundary for Li-ion flux, which cause larger surface areas than smooth particles. The finite element model of a LiMn 2 O 4 system is simulated under galvanostatic and potentiodynamic control. To investigate the realistic level of boundary flux at particle scale, macroscale simulation results are also applied to intercalationinduced stress analysis of real cathode particles. The numerical results of intercalation-induced stress show that the von Mises stress is concentrated at sharply dented boundaries due to curvature effects when Li ions intercalate or deintercalate and is an order-of-magnitude higher in realistic particle geometries than the stress in ideal smooth particles. It has also been shown that the stress under potentiodynamic control is higher than the stress under galvanostatic control because the high Li-ion flux at two plateaus in the open-circuit potential of a LiMn 2 O 4 system results from linear voltage sweep. We also present results showing that some mesh architectures are preferred for handling these potentially singular regions.

Design of Complexly Graded Structures inside Three-Dimensional Surface Models by Assigning Volumetric Structures

“…(a) Visualization of the surface representation of a sphere by means of triangles in the STL format [31]. (b) The same sphere in the AMF or OBJ format that allow assigning descriptive metadata to individual triangles, shown here as red color scheme in the upper part of the sphere.…”

Phase Field Modeling of Coupled Phase Separation and Diffusion-Induced Stress in Lithium Iron Phosphate Particles Reconstructed From Synchrotron Nano X-ray Tomography

“…There were some attempts to simulate the stress generation of realistic microstructures in LIBs. Zhang et al [31] studied the diffusion induced stresses of realistic geometry of LiMn2O4 particles reconstructed by atomic force microscopy. Wu et al [32] 4 investigated the mechanical behavior of LiMn2O4 cathode reconstructed by 2D SEM images under discharge conditions.…”

Insights Into Lithium-Ion Battery Degradation and Safety Mechanisms From Mesoscale Simulations Using Experimentally Reconstructed Mesostructures

“…At this scale, the complexshaped active material particles are bound together by the polymeric conductive binder into a bicontinuous (particle/binder and void/electrolyte phases) percolated network [7][8][9][10]. Intercalation of lithium into the particles results in swelling (volume change) of the particles [11,12], generating significant mechanical stress, potentially rearranging or damaging the network, and affecting the electrochemical performance [5,[13][14][15][16][17]. However, the scientific community generally has a lack of understanding of exactly what happens at the mesoscale.…”