Abstract

Real-time estimation of internal battery states is critical for predicting and controlling the complex electrochemical, thermal and mechanical behavior of lithium-ion batteries. In this presentation, I will highlight key accomplishments in:

 Inner-cell temperature estimation and associated monitoring of cell aging using non-uniform forgetting factors to capture the long term resistance growth.

 Investigations for sensor placement in large prismatic cells and pack thermal monitoring.

 Optimal control for fast warm-up from sub-zero temperatures.

 Real-time power limit to improve safety from thermal runaways.

 State of Charge (SOC) estimation augmented by bulk stress measurements utilizing the observed cell signature during lithium intercalation and thermal expansion.

 Estimation of individual cell SOC under cluster voltage measurements

If time allows, I will also show snapshots from our neutron imaging for in situ measurement of the lithium concentration inside a commercial Lithium Iron Phosphate (LFP) pouch cell battery to define the validity limits of various model simplifications such as the electrode-averaged assumption in single-particle battery models.

Supported by ARPA -E, US Army, NSF , NIST, A123 , Amphenol, GE, Ford

Bio Sketch:

Anna G. Stefanopoulou is a Professor at the Mechanical Engineering Department and the

Director of the Automotive Research Center at the University of Michigan. She is an ASME and an IEEE Fellow, the Founding Chair of the ASME DSCD Energy Systems Technical Committee, a member of the SAE Dynamic System Modeling Standards Committee and a member of a U.S. National Research Council committee on Vehicle Fuel Economy Standards. She has co-authored a book on Control of Fuel Cell Power Systems, 10 US patents, 5 best paper awards and more than 200 publications on estimation and control of internal combustion engines and electrochemical processes such as fuel cells and batteries.

http://www-personal.umich.edu/~annastef/