Numerical Simulation of Stress Evolution in Lithium Manganese Dioxide Particles due to Coupled Phase Transition and Intercalation

Abstract

Lithium manganese dioxide particles undergo a significant volume change after transition from the cubic to the tetragonal phase. The transition may cause severe damage in cathode materials and capacity fade. This paper proposes a volume expansion and diffusion model to evaluate stresses due to phase transition. A three-dimensional finite element approach is developed to account for coupled phase transition and intercalation effects, which is applicable to arbitrary particle geometries. The study shows that the stress levels are closely related to particle geometry, lithium diffusivity, and input current density. The stress due to phase transition is roughly an order of magnitude higher than that due to intercalation in the cubic phase. However, the interaction kinetics still plays an important role on the stress distribution because it affects the concentration profile and emergence of phase transition. Lower diffusivity and higher current density induce a larger gradient in the lithium concentration and lead to higher stress levels.