Anisotropic Mechanical Deformation of Lithium-Ion Electrode Networks Using Reconstructed Microstructures

Lithium-ion batteries are attractive for consumer electronics because of their high energy density, low self-discharge rates, and no memory effect.  However, like all rechargeable batteries, lithium-ion batteries suffer from capacity fade.  Understanding the mechanisms that lead to capacity fade in lithium-ion batteries is crucial for the advancement of lithium-ion battery technologies and the electronics relying on them for operation.  We hypothesize that one of the mechanisms leading to capacity fade arises due to mechanical stresses and changes to the connectivity of the electron transport network, which results from lithium intercalation reactions as batteries are cycled through charges and discharges.  Based on our hypothesis, we analyze these changes to the network structure by performing three-dimensional simulations of the particles at the mesoscale using reconstructed microstructures from SEM/EDS images of actual electrode particles.   We model the anisotropic swelling using coupled multi-physics simulations with a finite element code that encompasses mechanical, electrochemical, species transport, and thermal effects.  By incorporating all the aforementioned effects into our model, we hope to provide insight on how degradation of lithium-ion batteries evolves as a result of changes in the electron transport network arising from swelling, deformation, and stress generation driven by lithium intercalation.