From Electrode Materials to Dynamic Models of Li-Ion Cells
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Date
2013-05
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The Ohio State University
Abstract
Batteries play a fundamental role in electric vehicles, and help to reduce the environmental impact associated with fossil fuels. Li-ion battery is a promising candidate for vehicles due to its specific energy. This project is focused on experimental characterization and modeling of Li-ion batteries, and the objectives are to analyze battery aging at an electrode level and to better predict battery performance.The project consists of fabricating half cells of Lithium Iron Phosphate coin cells from unaged and batteries aged under different conditions, and measuring relevant parameters including capacity, state of charge, impedance, and open-circuit voltage. An equivalent circuit was developed from charging and discharging profile and impedance measurements with parameters calibrated to model the cell behavior. The governing equation of the non-linear system can be approximated by a Pade-function with second-order numerator and denominator. The disadvantage of Pade-function is that coefficients in the function do not have a physical meaning. The simple equivalent circuit and the linear Pade-function will allow fast calculations during design and prediction, and improve the efficiency of predictive maintenance.
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Li-Ion Battery Experimental Characterization and Modeling