A Model for Predicting Capacity Fade due to SEI Formation in a Commercial Graphite/LiFePO4 Cell

An aging model for a negative graphite electrode in a lithium-ion battery, for moderate currents up to 1C, is derived and fitted to capacity fade experimental data. The predictive capabilities of the model, using only four fitted parameters, are demonstrated at both 25 degrees C and 45 degrees C. The model is based on a linear combination of two current contributions: one stemming from parts of the graphite particles covered by an intact microporous solid-electrolyte-interface (SEI) layer, and one contribution from parts of the particles were the SEI layer has cracked due to graphite expansion. Mixed kinetic and transport control is used to describe the electrode kinetics. (C) The Author(s) 2015. Published by ECS. All rights reserved.