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Journal of the Electrochemical Society, Vol.159, No.6, A798-A808, 2012
A 3D Mesoscale Model of the Collector-Electrode Interface in Li-Ion Batteries
To gain insight into the collector-electrode interface in Li-ion batteries, a mesoscale model resolved at the particle scale in a representative volume element domain was developed. The underlying microstructure was first generated using a random packing and a dynamic collision algorithm. A finite element stress analysis was then used to calculate the deformations which are induced by Li-ion concentrations. The collector-electrode mechanical interaction was modeled using an adhesive contact law which was derived from the atomistic Lennard-Jones energy potential considering Van der Waals attractions. A finite element electrical analysis followed to calculate the collector contact resistance considering quantum tunneling currents. As a model application, we elaborated the role of the electrode microstructure by evaluating the damage and contact resistances for 8 various LiFePO4 based cathodes. We found that optimum interfaces would be achieved using a rough collector, low porosity, small particle sizes with disk like shapes and conductive additives in the interstitial sites. Pressure application was also beneficial. The developed model could be used either separately prior to commonly used porous electrode electrochemical models which require the collector-contact resistance as a parameter, or coupled in a 3D mesoscale electrochemical analysis so that a mechanical-electrochemical interaction would be considered. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.074206jes] All rights reserved.