title: Rate dependence of cell-to-cell variations of lithium-ion cells.
abstract: Lithium-ion cells are commonly used in a multicell configuration in power devices and electric vehicles, making the cell-to-cell variation (CtCV) a key factor to consider in system design and management. Previous studies on CtCV have two major limitations: the number of cells is usually less than one hundred, and the cells are usually commercial cells already subjected to cell-screenings. In this article, we first make a statistical analysis on the CtCV of 5473 fresh cells from an automotive battery manufacturer before the cell-screening process. Secondly, 198 cells are randomly selected from these 5473 cells and the rate dependence of the CtCV is examined, focusing on the correlations of capacity versus weight and capacity versus resistance, corresponding to thermodynamic and kinetic factors, respectively. The rate dependence of these two correlations is explained from a phenomenological model. Finally, eight cells from the 198 cells are further characterized with electrochemical impedance spectroscopy method to elucidate the kinetic origins of the CtCV.
authors.affiliation: Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China.|Boston-Power Battery, Inc. Westborough, USA.
authors.forename: Fuqiang
authors.initials: F
authors.lastname: An
authors.affiliation: Boston-Power Battery, Inc. Westborough, USA.
authors.forename: Lufan
authors.initials: L
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Automotive Safety and Energy, Department of Automotive Engineering, Tsinghua University, Beijing 100084, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Automotive Safety and Energy, Department of Automotive Engineering, Tsinghua University, Beijing 100084, China.|Beijing Co-innovation Center for Electric Vehicles, Beijing Institute of Technology, Beijing 100081, China.
authors.forename: Jianbo
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Li