A Multi-Scale Electrochemical and Thermal Model of a LiFePO4 Battery

Modeling and simulation of lithium batteries is becoming of in-creasing importance both for improving the fundamental under-standing of electrochemical processes and for developing battery management systems for practical applications. We present a 1D+1D+1D multi-scale electrochemical and thermal model of a lithium-ion battery with lithium iron phosphate (LiFePO4, LFP) positive electrode material. The model uses a hierarchical repre-sentation of spatial scales: On the nanoscopic level, diffusive transport takes place in the active material particles. On the micro-scopic level, multi-component mass and charge transport as well as heat production is described in a single repeat unit (anode, separa-tor, cathode, current collectors). On the macroscopic scale, the model describes heat transport in the radial direction of a cylindri-cal cell. Molar enthalpies and entropies are incorporated as func-tion of state of charge (SOC) for reliable simulation of heat pro-duction. The model is validated using experimentally-determined discharge curves over a wide range of discharge currents.