Performance of 26650 Li-ion cells at elevated temperature under simulated PHEV drive cycles. (27th April 2017)

• Record Type: Journal Article
• Authors: Badami, P.; Opitz, A.; Shen, L.; Vaidya, R.; Mayyas, A.; Knoop, K.; Razdan, A.; Kannan, A.M.
• Is Part Of: International journal of hydrogen energy. Volume 42:Number 17(2017)
• Page Start: 12396
• Page End: 12404
• Publication Date: 2017-04-27
• Subjects: Plug-in electric vehicles -- Charge sustaining mode -- Charge depleting mode -- Capacity fading -- LiFePO4 cathodes; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2017.02.004
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: Cylindrical (type: 26650) Li-ion cells (LiFePO4 cathodes) currently used in the electric vehicles (EVs), plug-in hybrid electric vehicles etc. were subjected to simulated federal urban driving schedule at 25 and 50 °C for performance evaluation. Drive profiles (current versus time) for charge sustaining and charge depleting modes were derived from the federal urban driving schedule velocity profiles considering acceleration, regenerative braking, rolling resistance, drag force etc. for typical plug-in hybrid electric vehicles. In particular, the batteries were cycled extensively at 50 °C under charge sustaining as well as charge depleting modes to monitor capacity values, followed by analyzing the LiFePO4 cathode material by X-ray diffraction analysis. The capacity degradation was found to be very significant in both the modes with 13 and 19% under charge sustaining and charge depleting modes after 337 and 1007 cycles, respectively at elevated temperature. High frequency resistance values measured by electrochemical impedance spectroscopy were found to increase significantly under high temperature cycling, leading to power fading. As evident from Rietveld analysis, phase change in LiFePO4 is observed beyond 1000 cycles at elevated temperature under charge depleting mode, with the observation of FePO4 from the powder diffraction data of the cathodes from the cycled cells. In addition, there was also significant change in crystallite size of the cathode active materials after charge/discharge cycling under charge depleting mode. Highlights: Li-Ion batteries were subjected to PHEV Drive profiles under FUDS. Capacity degradation under charge sustaining and depleting modes was observed. Phase change was observed for cathode with cycling, based on Rietveld analysis.