  In nanoparticulate phase-separating electrodes, phase separation inside the
particles can be hindered during their charge/discharge cycles even when a
thermodynamic driving force for phase separation exists. In such cases,
particles may (de)lithiate discretely in a process referred to as mosaic
instability. This instability could be the key to elucidating the complex
charge/discharge dynamics in nanoparticulate phase-separating electrodes. In
this paper, the dynamics of the mosaic instability is studied using Smoothed
Boundary Method simulations at the particle level, where the concentration and
electrostatic potential fields are spatially resolved around individual
particles. Two sets of configurations consisting of spherical particles with an
identical radius are employed to study the instability in detail. The effect of
an activity-dependent exchange current density on the mosaic instability, which
leads to asymmetric charge/discharge, is also studied. While we show that our
model reproduces the results of a porous-electrode model for the simple setup
studied here, it is a powerful framework with the capability to predict the
detailed dynamics in three-dimensional complex electrodes and provides further
insights into the complex dynamics that result from the coupling of
electrochemistry, thermodynamics, and transport kinetics.
