Lithium-ion batteries: Evaluation study of different charging methodologies based on aging process q Mohamed Abdel Monem a,b,⇑ , Khiem Trad b , Noshin Omar a , Omar Hegazy a , Bart Mantels b , Grietus Mulder a,b , Peter Van den Bossche a , Joeri Van Mierlo a a Vrije Universiteit Brussel, Pleinlaan 2, Brussels 1050, Belgium b VITO, Unit of Energy Technology, Boeretang 200, Mol 2400, Belgium highlights  Different charging methodologies have been tested and analyzed.  Battery impedance representation using the Randle’s equivalent circuit.  Investigate the impact of the charging methodology on the battery’s lifetime.  An extended analysis to select the proper charging method that can be used to design an enhanced charging system. article info Article history: Received 20 March 2014 Received in revised form 15 February 2015 Accepted 18 February 2015 Available online xxxx Keywords: Lithium-ion batteries Negative pulse charging Capacity fade Parameter estimation Electrochemical impedance analysis abstract In this paper, high power 7 A h LiFePO 4 -based cells (LFP) have been used to investigate the impact of the charging methodology on the battery’s lifetime. Three charging techniques have been used: Constant Current (CC), Constant Current–Constant Voltage (CC–CV) and Constant Current–Constant Voltage with Negative Pulse (CC–CVNP). A comparative study between these techniques is presented in this research. For this purpose, a characterization of the batteries has been performed using capacity test and electro- chemical impedance spectroscopy (EIS). As expected the obtained results showed that the battery’s aging rate depends on the charging methodology. Indeed, it has been shown that a combination of low ampli- tude and fewest number of negative pulses has a positive effect on battery’s capacity fading. From the impedance measurements, the results have demonstrated that the CC–CVNP technique with low ampli- tude and fewest number of negative pulses is more effective than the other techniques in reducing the concentration polarization resistance and the diffusion time constant. This research has provided an extended analysis to select the proper charging methodology that can be used to design an enhanced charging system. Ó 2015 Elsevier Ltd. All rights reserved. 1. Introduction Recently, lithium-ion batteries have been widely used in many portable electronic devices and vehicular applications. The lithium iron phosphate battery (LiFePO 4 ), known as a LFP battery, is a lithi- um-ion battery which uses LiFePO 4 as a positive electrode material. The LiFePO 4 has interesting characteristics such as low cost, low toxicity, flat charge–discharge potential, good cycle life and high structural stability, which meets the requirements for lithium ion batteries [1–6]. In order to characterize the LFP battery, it is neces- sary to investigate the impact of charging methodologies on the battery lifetime, internal impedance as well as the charging time. Indeed, the charging methodology plays an important role in the performance of the battery and in its lifetime and reliability [7,8]. In order to know the influence of the charging methodologies on the LFP battery lifetime, different charging methodologies were studied in [7,9,10]. It is noticed that the constant current CC and the constant cur- rent–constant voltage CC–CV techniques are widely used in the lit- erature. Compared to the CC charging technique, the CC–CV charging technique allows an almost full battery capacity but it increases the charging time. Furthermore, different charging tech- niques have been studied to achieve high performance, short charg- ing time and high reliability, such as dynamic pulse charging http://dx.doi.org/10.1016/j.apenergy.2015.02.064 0306-2619/Ó 2015 Elsevier Ltd. All rights reserved. q This paper is included in the Special Issue of Energy Storage edited by Prof. Anthony Roskilly, Prof. Phil Taylor and Prof. Yan. ⇑ Corresponding author at: Vrije Universiteit Brussel, Pleinlaan 2, Brussels 1050, Belgium. E-mail address: mohamed.abdel.monem@vub.ac.be (M. Abdel Monem). Applied Energy xxx (2015) xxx–xxx Contents lists available at ScienceDirect Applied Energy journal homepage: www.elsevier.com/locate/apenergy Please cite this article in press as: Abdel Monem M et al. Lithium-ion batteries: Evaluation study of different charging methodologies based on aging pro- cess. Appl Energy (2015), http://dx.doi.org/10.1016/j.apenergy.2015.02.064