Combining an Electrothermal and Impedance Aging Model to Investigate Thermal Degradation Caused by Fast Charging

Abstract

Fast charging is an exciting topic in the field of electric and hybrid electric vehicles (EVs/HEVs). In order to achieve faster charging times, fast-charging applications involve high-current profiles which can lead to high cell temperature increase, and in some cases thermal runaways. There has been some research on the impact caused by fast-charging profiles. This research is mostly focused on the electrical, thermal and aging aspects of the cell individually, but these factors are never treated together. In this paper, the thermal progression of the lithium-ion battery under specific fast-charging profiles is investigated and modeled. The cell is a Lithium Nickel Manganese Cobalt Oxide/graphite-based cell (NMC) rated at 20 Ah, and thermal images during fast-charging have been taken at four degradation states: 100%, 90%, 85%, and 80% State-of-Health (SoH). A semi-empirical resistance aging model is developed using gathered data from extensive cycling and calendar aging tests, which is coupled to an electrothermal model. This novel combined model achieves good agreement with the measurements, with simulation results always within 2°C of the measured values. This study presents a modeling methodology that is usable to predict the potential temperature distribution for lithium-ion batteries (LiBs) during fast-charging profiles at different aging states, which would be of benefit for Battery Management Systems (BMS) in future thermal strategies.

A Comparison of Internal and External Preheat Methods for NMC Batteries

“…It is capable of estimating the heat transfers and the energy losses and it is coupled with a lifetime function to determine the total energy cost efficiency, due to cycle degradation that occurs during the preheat methods on the battery cell. Authors invite the reader to refer to previous articles [13,14] for more information about the model description and parameterization as well as the experimental protocols followed to characterize the battery cell. In particular, the hybrid pulse power characterization (HPPC) is performed to give information on the DC resistance of the battery cell and its power capabilities, the open circuit voltage test is performed to show the voltage of the battery at different SoC levels and the capacity test which is performed to give the discharge capacity of the battery cell at different current rates [15,16].…”

Hybrid Battery/Lithium-Ion Capacitor Energy Storage System for a Pure Electric Bus for an Urban Transportation Application

“…The lifetime model was developed using an empirical approach, as explained in [19]. The capacity degradation trend and internal resistance increase for both the calendaring and cycling aging phenomena were investigated fully and based on the curve fitting techniques.…”

Design and Experimental Verification of Voltage Measurement Circuits Based on Linear Optocouplers with Galvanic Isolation for Battery Management Systems

“…The thermal management as a BMS future is investigated from papers [7][8][9], with interesting simulation and experimental results, including a fast battery charge mode. The obtained results show that the suggested circuit for galvanic isolation does not affect the thermal measurement modules and their correct operation as they are separated from the voltage measurement circuits.…”