Adaptive Fast Charging Methodology For Commercial Li-Ion Batteries Based On The Internal Resistance Spectrum

Development of lithium-ion batteries (LIBs) with high energy density has brought a promising future for the next generation of electric vehicles (EV). In order to make EVs more competitive with combustion engine vehicles, development of an effective fast charging technique is inevitable. However, improper employment of fast charging can damage the battery and bring safety hazards. Herein, industry based along with our proposed internal resistance (IR) based fast charging techniques were performed on commercial Panasonic NCR 18650B cylindrical batteries. To further investigate the fast charging impact and electrode degradation mechanisms, electrochemical analysis and material characterization techniques including EIS (electrochemical impedance spectroscopy), GITT (galvanostatic intermittent titration technique), SEM (scanning electron microscopy), and XRD (X-ray diffraction) were implemented. Batteries that were cycled under industry based fast charging showed 78% increase in internal resistance after 120cycles along with rapid capacity fading. Mechanical distortion of the battery case occurred around the 60th cycle for industry based fast charging. In contrast, IR based fast charged batteries showed 29.4% increase in internal resistance over 120cycles. In addition, mechanical distortion was not observed and the relative capacity fading was on a moderate level. Furthermore, this work could pave the way for the optimization of fast charging techniques to secure the lifespan and safety of various types of lithium-ion batteries.