Multiphysics SimulatiOns of Lithiation-Induced Stress in Li1+xTi2O4 Electrode Particles

Cubic spinel Li1+xTi2O4 is a promising electrode material because it exhibits a high lithium diffusivity and undergoes minimal changes in lattice parameters during lithiation and delithiation, thereby ensuring favorable cyclability. The present work is a multiphysics and multiscale study of Li1+xTi2O4 that combines first-principles computations of thermodynamic and kinetic properties with continuum scale modeling of lithiationdelithiation kinetics. Density functional theory calculations and statistical mechanics methods are used to calculate lattice parameters, elastic coefficients, thermodynamic potentials, migration barriers, and Li diffusion coefficients. These computations were performed at a temperature of 800 K to magnify the kinetic effects. These quantities then inform a phase field framework to model the coupled chemo-mechanical evolution of electrode particles. Several case studies accounting for either homogeneous or heterogeneous nucleation are considered to explore the temporal evolution of maximum principal stress values, which serve to indicate stress localization and the potential for crack initiation, during lithiation and delithiation.