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Second-life applications for lithium-ion batteries offer the industry opportunities to defer recycling costs, enhance economic value, and reduce environmental impacts. An accurate prognosis of the remaining useful life (RUL) is essential for ensuring effective second-life operation. Diagnosis is a necessary step for the establishment of a reliable prognosis, based on the aging modes involved in a cell. This paper introduces a method for characterizing specific aging phenomenon in Graphite/Lithium Iron Phosphate (G/LFP) cells. This method aims to identify aging related to the loss of active material at the negative electrode (LAMNE). The identification and tracking of the state of health (SoH) are based on Incremental Capacity Analysis (ICA) and Differential Voltage Analysis (DVA) peak-tracking techniques. The remaining capacity of the electrode is thus evaluated based on these diagnostic results, using a model derived from half-cell electrode characterization. The method is used on a G/LFP cell in the format 18650, with a nominal capacity of 1.1 Ah, aged from its pristine state to 40% of state of health. [ABSTRACT FROM AUTHOR]

Second-life applications for lithium-ion batteries offer industry opportunities to defer recycling costs, enhance economic value, and reduce environmental impacts. However, cells are affected by numerous aging phenomena which can lead to an acceleration in capacity loss. This paper uses postmortem techniques to compare aging phenomenon in 1.1 Ah 18650 graphite/LFP cells, examining the differences between a pristine cell and three cells aged to 40~30% of state of health (SoH). Macroscopic and microscopic techniques are used to identify aging phenomenon occurring in the cell on both positive and negative electrodes. Energy-dispersive X-ray spectroscopy (EDXS) and scanning electron microscopes (SEMs) with back-scattered electron (BSE) detector are used to analyze each electrode. These methods are used to analyze the morphology and the material on each electrode. The results show a stable positive LFP electrode whereas numerous deposits and cracking occurred on the negative electrode. A discussion of the appearance of those aging phenomenon is presented. Impacts for industrial cells in second-life applications are finally discussed. [ABSTRACT FROM AUTHOR]

The process of determination of batteries lifespan for a specific application generally contains some aging tests. Most of the time, these tests used simplified power or current profiles designed specially to be as representative as possible of the reality. The use of a real profile could improve the reliability of the approach but needs to know how to select the typical profile from an available database. This article shows the methodology used to analyze a database of 10 electric vehicles monitored during 2 years. Different mathematical methods (Pearson and Spearman coefficient of correlation, Shannon entropy, principal component analysis, K-means, …) were applied to sort the essential variables and classify the uses of the vehicle. Representative classes of uses were then gathered to constitute a profile used in aging tests. The aging results with this real-life type profile and with an adjusted WLTC (Worldwide Harmonized Light Vehicles Test Cycles) profile are presented and compared. The effectiveness of the use of the WLTC profile for aging tests in real life automotive application is shown. [ABSTRACT FROM AUTHOR]

In this paper, we present an innovative and precise way to calculate the available capacity in a battery. This quantity is essential to assess the ageing process during real use or ageing tests. Classical methods for measuring the available capacity in a battery are very dependent of impedance and relaxation state of the battery. Consequently, these methods are not suitable to quantify reversible and irreversible capacity losses occurring on batteries. We propose an indirect measure of available capacity that reduces the distortion caused by battery relaxation and impedance changes. This new method provides more accurate results allowing to distinguish reversible from irreversible part of capacity losses. The obtained results on calendar ageing tests are used in a second part to model both self-discharge and capacity fade in a global approach by using the generalized Eyring relationship. [ABSTRACT FROM PUBLISHER]

Despite their great improvements, reliability and availability of power electronic devices always remain a focus. In safety-critical equipment, where the occurrence of faults can generate catastrophic losses, health monitoring of most critical components is absolutely needed to avoid and prevent breakdowns. In this paper, a noninvasive health monitoring method is proposed. It is based on fuzzy logic and the neural network to estimate and predict the equivalent series resistance (ESR) and the capacitance (C) of capacitors and supercapacitors (SCs). This method, based on the neo-fuzzy neuron model, performs a real-time processing (time series prediction) of the measured device impedance and the degradation data provided by accelerated ageing tests. To prove the efficiency of the proposed method, two experiments are performed. The first one is dedicated to the estimation of the ESR and C for a set of 8 polymer film capacitors, while the second one is dedicated to the prediction of the ESR and C for a set of 18 SCs. The obtained results show that combining fuzzy logic and the neural network is an accurate approach for the health monitoring of capacitors and SCs. [ABSTRACT FROM PUBLISHER]

Energy storage elements such as supercapacitors are widely used in high-power applications. However, due to single cell voltage limitation, an energy storage system with a large number of supercapacitors is often employed. Energy management systems are associated to energy storage systems in order to assure user and equipment safety. Balancing circuits, which enable the equalization of the voltage of each element in series, are a part of the energy management system device. The work presented in this paper aims to enhance the lifetime of energy storage systems. It relies on better controlling balancing circuits on the terminals of the storage system elements. With the conventional function of balancing circuit, the energy storage system is limited by its weakest element that may fail prematurely. Thus, a new balancing approach is presented, discussed, and analyzed. It is based on the elements degradation level prediction. The model predictive control used with the new approach aims to equalize aging speed between elements of a module and ensures a maximum lifetime to the energy storage system. A comparison with the conventional control shows that adopting this new approach, with the same equipment, can enhance the storage system's lifetime by dozens percent. [ABSTRACT FROM AUTHOR]

Compared to Li-ion batteries, supercapacitors (SCs) boast longer lifespan, higher power density, and wider operational temperature range. Nevertheless, SCs are expensive (almost 40 times more expensive per watthour than Li-ion batteries). SCs aging is critical. Two types of aging tests are usually performed. Floating aging tests apply constant constraints (voltage and temperature), and cycling aging tests apply multiple charges and discharges. We focus our study on floating aging [corresponding for instance to parking mode for electrical vehicles (95% of the time) or uninterruptible power supplies (UPSs) when they are not solicited (quite all the time)]. All results in the literature conclude that voltage level is an acceleration factor for SC aging. According to the literature, it would be interesting to totally discharge the SCs when they are not in active use (i.e., when the UPSs or vehicles are turned off) to improve their lifespan. Contrary to the literature forecasts (i.e., lower voltage increases lifespan of SC), the results obtained in this paper by alternating voltage resets (0 V, 60 °C) and floating aging (2.8 V, 60 °C) show that discharging even very few times the SCs shortens their lifespan drastically. Physical interpretations are presented to explain aging increase with voltage resets. [ABSTRACT FROM AUTHOR]

Lithium-ion (Li-ion) batteries widely used in electric vehicles (EVs) and hybrid EVs (HEVs) are insufficient for vehicle use after they have degraded to 70% to 80% of their original capacity. Battery lifespan is a large consideration when designing battery packs for EVs/HEVs. Aging mechanisms, such as metal dissolution, growth of the passivated surface film layer on the electrodes, and loss of both recyclable lithium ions, affect the longevity of the Li-ion battery at high-temperature operations. Even vehicle maneuvers at low temperatures (T < \mbox0\ ^\circ\mboxC) contribute to battery lifetime degradation, owing to the anode electrode vulnerability to other degradation mechanisms such as lithium plating. Nowadays, only a few battery thermal management schemes have properly considered low-temperature degradation. This is due to the lack of studies on aging of Li-ion batteries at subzero temperature. This paper investigates how load cycle and calendar life properties affect the lifetime and aging processes of Li-ion cells at low temperatures. Accelerated aging tests were used to determine the effect of the ambient temperature on the performance of three 100-Ah LiFeMnP04 Li-ion cells. Two of them were aged through a normalized driving cycle at two temperature tests ( -\mbox20\ ^\circ\mboxC and 25 °C). The calendar test was carried out on one single battery at –20 °C and mid-range of state of charge (50%). Their capacities were continuously measured every two or three days. An aging model is developed and added to a preliminary single-cell electrothermal model to establish, in future works, a thermal strategy capable of predicting how the cell ages. This aging model was then validated by comparing its predictions with the aging data obtained from a cycling test at 0 °C. [ABSTRACT FROM PUBLISHER]

Supercapacitors (SCs) impedance modeling represents one important key to get information for SCs health monitoring and simulation. As a matter of fact, SCs behavior is dependent on various parameters such as pore size distribution of electrodes, electrolyte state, temperature, aging, etc. We propose in this study to model SC taking into account physical considerations. Basing on the theory on homogenous structure impedance, we first define the single pore model using the uniform size of pores distribution. In the second step, we attempt to generalize this circuit model considering an electrode with different pores sizes or different penetrabilities of the pores. This model called multipore (MP) model (or multipenetrability model) has been developed by our laboratories. This model allows analyzing the behavior of SC by modeling each group of electrode pores as a branch of an electrical equivalent circuit. This paper is the first in the literature to give a simple and reproducible method for MP model parameters identification. The validity of the identification method will also be verified at different SC aging rates thanks to experimental aging tests. [ABSTRACT FROM AUTHOR]

This paper proposes an original model for supercapacitors that takes into account both calendar aging and cycling aging. A state variable is used to quantify the state of aging. This model is based on a series of recent experiments conducted in various research laboratories on the same technology (Maxwell Technology) and serves to represent the degradation of equivalent series resistance and capacitance. This model is particularly useful in an aging-aware life-cycle cost analysis. We show that an accurate aging model is critical to the design of an energy storage system that optimizes the economic life-cycle cost. Such an optimization is particularly applicable for smoothing in offshore systems such as direct wave energy converters, which require both cost reduction and high reliability. The influence of an aging model in the sizing process is investigated toward the end of this paper. [ABSTRACT FROM AUTHOR]

Due to its capacity to store or supply energy with high power, the supercapacitor is becoming an attractive component. Because of the electrostatic nature of energy storage, the endurance of this component toward repetitive charge and discharge cycles is relatively high. The goal of this paper is to demonstrate that cycling has an impact on the degradation of the supercapacitor and, as a result, on its lifetime. Based on accelerated cycling tests, some supercapacitors were studied using a dedicated test bench. Temperature, voltage, and current, which are the parameters that accelerate aging, are monitored. In fact, observations during the cycling tests show an important acceleration in the degradation compared with a similar static test having the same voltage and core temperature but without cycling. This paper proposes a method to quantify the acceleration of aging during a cycling phase. [ABSTRACT FROM PUBLISHER]

Like any electric energy storage system, supercapacitors have a limited lifetime. Indeed, they degrade with time because of parasitic reactions between electrodes and electrolyte. Porous electrodes are complex structures and pores have size dispersion because of manufacturing processes. This paper proposes to study the specific impact of supercapacitor floating ageing on different pore sizes using a multipore model. The multipore model is an equivalent electrical circuit model, capable of representing impedance behavior of supercapacitor in full range of its operating frequencies and classifying different sized pores by their impedance parameters. This paper first presents a link between pore sizes and impedance parameters of the modeling circuit. Then, floating ageing experiments are carried out using three samples from two different manufacturers. Multipore model impedance parameters evolution is monitored and discussed. Finally, a new representation of ageing processes is proposed by pore size and for different ageing phases. [ABSTRACT FROM AUTHOR]