Fast Charging Effects Research Articles

Effect of fast charging on degradation and safety characteristics of lithium-ion batteries with LiFePO4 cathodes

Fast charging compatibility is a desirable feature for batteries to shape a promising future in our rechargeable world. Enabling fast charging of advanced energy-dense Li-ion batteries for growing electric vehicle (EV) markets depends on the breakthrough of material chemistry and optimization of charging strategy. Lithium iron phosphate (LiFePO4, or LFP) is a pivotal cathode material in state-of-the-art EV batteries due to the merits of high thermal stability, long cycle lifetime, and high-temperature performance. However, degradation-safety interactions of LFP-based Li-ion batteries under fast charging conditions and low temperatures remain elusive. In this study, we cycle LFP cells under different fast charging strategies and thermal environments to understand their effects on degradation pathways, where the capacity, voltage, temperature, coulombic inefficiency, internal resistance, and impedance spectroscopy are evaluated. Half-cell studies are implemented to assess electrode-level capacity retentions. Post-mortem analyses are conducted to reveal physicochemical changes in electrodes. Accelerating rate calorimeter tests are carried out to measure evolutions of cell-level thermal instabilities after fast charging tests. This research article highlights the significant roles of graphite-centric lithium plating and LFP-centric transition metal dissolution in driving substantial electrochemical degradations, suggesting that a mild low temperature does not necessarily reduce the LFP cell lifetime.

Effect of fast charging on degradation and safety characteristics of lithium-ion batteries with LiNixCoyMnzAl1-x-y-zO2 cathodes

Fast charging compatibility is an important technical aspect required of advanced lithium-ion (Li-ion) batteries to lead the revolution and increase the adoption of electric vehicles. Although substantial material-level innovations have greatly promoted the widespread employment of fast charging rates for Li-ion batteries, the unfavorable rapid degradation and cell-level thermal instability are still bottlenecks for commercial success. In this study, fast-charging induced aging mechanisms and thermal safety characteristics of Li-ion batteries with quaternary energy-dense LiNixCoyMnzAl1-x-y-zO2 (NCMA) cathodes are comprehensively investigated. Promising fast-charge strategies under different thermal environments are applied to reveal their specific adverse side effects on electrochemical performances and cell lifetime. Post-mortem analysis is conducted to understand the distributions, microstructures, and chemical states of electrodepositions on cell components. Cell-level thermal safety evaluations are carried out based on accelerating rate calorimeter tests to determine evolutions of thermal safety hazards as a result of imposed fast charging conditions. This research highlights the significant role of lithium plating and aluminum dissolution in accelerating the thermo-electrochemical failure of the chosen NCMA-based Li-ion chemistry, providing new insights on degradation-safety interactions and effective mitigation strategies under fast charging conditions.

Effect of Fast Charging on Lithium-Ion Batteries: A Review

<div>In recent years we have seen a dramatic shift toward the use of lithium-ion batteries (LIB) in a variety of applications, including portable electronics, electric vehicles (EVs), and grid storage. Even though more and more car companies are making electric models, people still worry about how far the batteries will go and how long it will take to charge them. It is common knowledge that the high currents that are necessary to quicken the charging process also lower the energy efficiency of the battery and cause it to lose capacity and power more quickly. We need an understanding of atoms and systems to better comprehend fast charging (FC) and enhance its effectiveness. These difficulties are discussed in detail in this work, which examines the literature on physical phenomena limiting battery charging speeds as well as the degradation mechanisms that typically occur while charging at high currents. Special consideration is given to charging at low temperatures. The consequences for safety are investigated, including the possible impact that rapid charging could have on the characteristics of thermal runaway (TR). In conclusion, knowledge gaps are analyzed, and recommendations are made as regards the path that subsequent studies should take. Furthermore, there is a need to give more attention to creating dependable onboard methods for detecting lithium plating (LP) and mechanical damage. It has been observed that robust charge optimization processes based on models are required to ensure faster charging in any environment. Thermal management strategies to both cool batteries while these are being charged and heat them up when these are cold are important, and a lot of attention is paid to methods that can do both quickly and well.</div>

Battery lifetime of electric vehicles by novel rainflow-counting algorithm with temperature and C-rate dynamics: Effects of fast charging, user habits, vehicle-to-grid and climate zones

The adoption of electric vehicles is expected to soon widespread to cope with energy transition needs; however, concerns on battery lifetime arise, especially related to charging behaviors, vehicle usage habits, vehicle-to-grid and weather conditions. In fact, lifetime battery modeling is a challenging dynamic to characterize, as it involves complex chemical processes related to charging, discharging and temperature dynamics over long time spans that are often difficult to dominate, given the large uncertainties. Having a fatigue-like behavior, the battery aging has sometimes been modeled using rainflow-counting algorithms, yet traditional modeling is not holistic and approximations are used, especially when considering temperature or current dynamics. Based on experimental data, this paper aims at developing a holistic battery degradation model based on rainflow-counting algorithm to properly account for all major determinants of capacity loss, namely cycling usage, calendar lifetime, dynamic temperature and battery current. The approach is coupled with a physical-electro-thermal modeling of the vehicle system, developed in Modelica language, to accurately simulate the intertwined thermal and electrical behavior of the system subject to different usage charging behaviors, including slow and fast charging, as well as vehicle-to-grid application. The proposed case study shows the expected lifetime of electric vehicles to be comparable with of traditional cars (10–20y) and that the proposed temperature-dependent battery modeling enables reducing estimation errors up to 27%. A sensitivity on different climate zones has been considered and results suggest that cool climates can increase life expectancy by 30% with respect to hot climates in typical Italian contexts.

The effect of fast charging and equalization on the reliability and cycle life of the lead acid batteries

Three-wheeled e-rickshaws driven by lead-acid batteries are a common means of transport in Asian countries due to their low cost, and durability. Conventional charging is time-consuming and lacks proper controls for the termination of the charge. Though fast charging can significantly reduce the charging time to about one-third or less, it is prone to temperature rise, excessive gassing, and reduction in the useful life of the battery. A new fast-charging procedure along with periodic equalizing is proposed in this paper. A multistage constant current fast charger with depolarization pulse was used to charge a 48 V e-rickshaw battery pack in 3 h 37 min from 20 % to 80 % state of charge. The effect of the said fast charging procedure on the coulombic efficiency, end voltage pattern, capacity degradation, reliability, and useful life of the lead-acid batteries is investigated. Experimental results for 150 charging-discharging cycles show a temperature rise up to 5–6 °C, average coulombic efficiency of 93 %, and a maximum top-of-charge voltage of 2.6 Volts Per Cell (VPC). Attainment of such a low-temperature rise coupled with high coulombic efficiency during fast charge is the most competitive result reported for commercial batteries.A regression model and best-fit probability distribution (Weibull 3-parameter distribution) are used to estimate the degradation rate, and Cycle-To-Failure (CTF). The expected life of the batteries subjected to such a fast charging and equalizing charge is predicted to be 1296 cycles, which is about 2 times the current life of the battery. The proposed fast charger along with periodic equalizing is, therefore, a promising and sustainable option for charging lead-acid batteries.

Effects of Fast Charging at Low Temperature on a High Energy Li-Ion Battery

Understanding the impact of repeated fast charging of Li-ion batteries, in particular at low temperatures, is critical in view of the worldwide deployment of EV superchargers. In this study, the effects of fast charging using the conventional CCCV protocol on the performances of a high energy cell were investigated. The fast charging capability was confirmed to be negatively affected by low temperatures. The cell was capable of sustaining repeated fast charging at 23 °C without notable performance degradation, but quickly degraded when the charging temperature was decreased. Post-mortem analysis revealed several failure modes, including lithium plating, graphite exfoliation, jelly-roll deformation, active materials crumbling, aluminum corrosion and an abnormal SEI growth on the anode side. A loss of lithium inventory, mainly due to lithium plating and subsequent SEI growth was identified to be the major cause of performance degradation related to repeated fast charging at low temperatures. These results clearly put in evidence that repeated fast charging can cause significant degradations in Li-ion cells, with detrimental consequences in safety, performance and service life. Gaining insights into the failure modes related to repeated fast charging shall guide battery developers towards the optimization of Li-ion cells for EV application.

Effect of Fast-Charging on Ageing of Energy-Optimized Automotive LiNi1/3Mn1/3Co1/3O2/Graphite Prismatic Lithium-Ion Cells

It is desirable to be able to charge automotive batteries at a fast rate, especially for heavy duty commercial vehicles. In this study [1] the effect of fast charging (1C-4C) on ageing was studied on an energy-optimized 25 Ah prismatic NMC(III)/graphite lithium-ion cell cycled at 35°C and 20-80% SOC. Detailed post-mortemanalysis was carried out using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and electrochemical impedance spectroscopy (EIS). The results show that the effect of charging rate is more complex than earlier described. Even though ageing is more rapid at 3 and 4C charging, no clear trends in degradation with charging rate are observed. Instead, different mechanisms are dominating at the different charging rates. Accelerated lithium plating was observed after cycling at 3C-charging, while extensive gas evolution was the cause to the fast cell impedance rise and capacity fade of the cells cycled at 4C. Graphite exfoliation and accelerated lithium inventory loss point to the graphite electrode as the source of the gas evolution. SEM show cathode particle cracking independent of the charging rate used for the cycling. XPS and EIS generally indicate thicker surface film and larger impedance, respectively, towards the edge of the cells. The results implicate that the ageing rates are too high to be feasible for a battery electric inner-city bus using this type of cell being charged at 3C. However, even though ageing rates for 2C and below are acceptable, it is concluded too slow from the point of view of practical charging time. Fig. Capacity fade vs. number of equivalent full cycles (inset: capacity fade vs. cycling time). Fast-charging effects on ageing for energy-optimized automotive LiNi1/3Mn1/3Co1/3O2/ graphite prismatic lithium-ion cells. Abdilbari Shifa Mussa, Anti Liivat, Fernanda Marzano, Matilda Klett, Bertrand Philippe, Carl Tengstedt, Göran Lindbergh, Kristina Edström, Rakel Wreland Lindström, Pontus Svens, Journal of Power Sources 422, 2019, 175-184.

Fast-charging effects on ageing for energy-optimized automotive LiNi1/3Mn1/3Co1/3O2/graphite prismatic lithium-ion cells

The reactions in energy-optimized 25 Ah prismatic NMC/graphite lithium-ion cell, as a function of fast charging (1C4C), are more complex than earlier described. There are no clear charging rate dependent trends but rather different mechanisms dominating at the different charging rates. Ageing processes are faster at 3 and 4C charging. Cycling with 3C-charging results in accelerated lithium plating but the 4C-charging results in extensive gas evolution that contribute significantly to the large cell impedance rise. Graphite exfoliation and accelerated lithium inventory loss point to the graphite electrode as the source of the gas evolution. The results are based on careful post-mortem analyses of electrodes using: scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and electrochemical impedance spectroscopy (EIS). SEM results show particle cracking independent of the charging rate used for the cycling. XPS and EIS generally indicate thicker surface film and larger impedance, respectively, towards the edge of the jellyrolls. For the intended application of a battery electric inner-city bus using this type of cell, charging rates of 3C and above are not feasible, considering battery lifetime. However, charging rates of 2C and below are too slow from the point of view of practical charging time.

Effects of Fast Charging on Lithium-Ion Cells

As electrified vehicles become widely accepted, consumers expect the characteristics to be similar to those with a conventional, internal-combustion engine. Among these is the ability to ‘refuel’ quickly. For example, current lithium-ion battery technology takes an hour or more to recharge (refuel) whereas a conventional car can take 5 minutes or less. Some work has been does to understand the electrical effect fast charging lithium-ion cells has. However, no one understands what faster charging does to internal cell components. We cycled commercially-available 18650 cells at four different charge C-rates (0.7, 2, 4, 6) and two different charge-returned windows (40% and 100%); the discharge rate was C/3. The cells were opened and both electrodes as well as separator were analysed in an argon-environment glove box using a range of surface-sensitive, analytical techniques. The binder material at the negative electrode decomposed at higher C-rates causing delamination from the copper current collector. Surprisingly, cells cycled within a smaller charge-returned window completely delaminated irrespective of C-rate, suggesting there are at least two different mechanisms responsible for electrode delamination in the cells. Analysis of surface film chemistry and thickness showed a dependence on C-rate. Cells cycled at higher C-rates had a thicker surface film and a more complex chemistry. Gel permeation - liquid chromatography showed that the surface film of the cells was extremely complex, with a large range of molecular weights (MW). As the C-rate increased, the average MW of the oligomers from the surface film also increased. These findings indicate that an increased charging rate affects the negative electrodes surface film and its adhesion to the current collector. Although a smaller SoC window caused less resistance increase and capacity losses in 18650 cells it was detrimental to the lamination properties. This could have significant implications for unconstrained pouch cells.

Effects of fast charging on hybrid lead/acid battery temperature

The effects of very fast charging on two types of deep-cycling hybrid lead/acid batteries were determined using a MINITCHARGER TM to control the charging current. One of the hybrid batteries was flooded and contained Pb-4.7wt.%Sb positive grids, the other was a valve-regulated battery with Pb-1.5wt.%Sb-0.3wt.%Sn positive grids. Results are presented and discussed in relation to these battery types, but many of the conclusions are more generally applicable. It was found that both 5-min/50%-recharge and 15-min/80%-recharge rates could be achieved, in the case of the flooded battery, with a quite acceptable temperature increase. Following an 80% depth-of-discharge, the dominant source of heat was ohmic during the first 40% of the charge returned at very high rates. The temperatures were distributed non-uniformly within the battery. After this, non-ohmic polarization became progressively more important. For the hybrid recombination battery, the oxygen cycle is a substantial source of heat during the latter stages of the charge, particularly in comparison with previous non-antimonial batteries that have been investigated.