Viscoplastic response of electrode particles in Li-ion batteries driven by insertion of lithium

Constitutive equations are derived for the viscoplastic behavior of a host medium driven by diffusion of guest atoms. With reference to the trapping concept, two states of a guest atom are distinguished: mobile and immobilized (due to alloying with the host matrix). This allows propagation of a sharp interphase to be described between regions rich and poor in guest atoms. The model is applied to study the mechanical response of a spherical electrode particle in a Li-ion battery. Ability of the constitutive equations to capture basic phenomena observed in anode particles under lithiation is demonstrated by numerical simulation.