  In this paper, a core-shell enhanced single particle model for iron-phosphate
battery cells is formulated, implemented, and verified. Starting from the
description of the positive and negative electrodes charge and mass transport
dynamics, the positive electrode intercalation and deintercalation phenomena
and associated phase transitions are described with the core-shell modeling
paradigm. Assuming two phases are formed in the positive electrode, one rich
and one poor in lithium, a core-shrinking problem is formulated and the phase
transition is modeled through a shell phase that covers the core one. A careful
discretization of the coupled partial differential equations is proposed and
used to convert the model into a system of ordinary differential equations. To
ensure robust and accurate numerical solutions of the governing equations, a
sensitivity analysis of numerical solutions is performed and the best setting,
in terms of solver tolerances, solid phase concentration discretization points,
and input current sampling time, is determined in a newly developed
probabilistic framework. Finally, unknown model parameters are identified at
different C-rate scenarios and the model is verified against experimental data.
