Abstract
The fabrication of tin (Sn)-based materials with exceptional electrochemical and mechanical properties requires a thorough understanding of the multiphase evolution that occurs during lithiation. However, predicting the microstructural changes during this process using analytical models is challenging due to the intricate interactions among electrode materials, cell operating parameters, complex geometries, and polycrystalline structures. To tackle this challenge, we propose the application of the phase-field method in a grand-potential formulation, that is combined with the smooth boundary method to apply constant-current (de-)lithiation boundary conditions. This approach effectively describes the migration of lithium and the multiphase transitions in polycrystalline electrodes with arbitrary geometries. To investigate nanoparticles with hundreds of grains in two/three dimensions efficiently, we have incorporated this model into the self-developed open-source phase-field solver package MInDes in a highly optimized manner. Further, comparing the output voltage of the simulated lithiation process of LixSn nanoparticles in three dimensions demonstrates an excellent correlation with experimental results. Based on this, we analyze the mechanical performance of polycrystalline nanoparticles with varying amounts of copper doping and evaluate the maximal von Mises stress during lithiation to predict the onset of crack formation.
Published Version
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