Li-ion Battery System Research Articles

Simulation, Set-Up, and Thermal Characterization of a Water-Cooled Li-Ion Battery System

A constant and homogenous temperature control of Li-ion batteries is essential for a good performance, a safe operation, and a low aging rate. Especially when operating a battery with high loads in dense battery systems, a cooling system is required to keep the cell in a controlled temperature range. Therefore, an existing battery module is set up with a water-based liquid cooling system with aluminum cooling plates. A finite-element simulation is used to optimize the design and arrangement of the cooling plates regarding power consumption, cooling efficiency, and temperature homogeneity. The heat generation of an operating Li-ion battery is described by the lumped battery model, which is integrated into COMSOL Multiphysics. As the results show, a small set of non-destructively determined parameters of the lumped battery model is sufficient to estimate heat generation. The simulated temperature distribution within the battery pack confirmed adequate cooling and good temperature homogeneity as measured by an integrated temperature sensor array. Furthermore, the simulation reveals sufficient cooling of the batteries by using only one cooling plate per two pouch cells while continuously discharging at up to 3 C.

Method for analyzing in-situ volume change of large format lithium-ion hard case cells

To achieve high volumetric energy density in li-ion battery systems, it is relevant to predict the required space for reversible and irreversible volume change of the battery cells. In prismatic hard case cells, a locally inhomogeneous change in thickness occurs due to the rigid housing, which makes geometric analysis much more difficult. This publication highlights the challenges of analyzing prismatic hard case cells with existing test benches. In addition, an innovative test method is presented, in which the cells are both, compressed by air pressure and measured three-dimensionally. Influences such as gas inclusions between the electrode layers or plastic deformations of the housing can be reduced or even eliminated. This method enables a clear description of the local cell thickness at defined pressure, state of charge (SOC) and energy throughput (ETP). The resulting data can be used for a 3D simulation to estimate the required installation space within a battery system and the resulting force and pressure.

A single dual-mode gas sensor for early safety warning of Li-ion batteries: Micro-scale Li dendrite and electrolyte leakage

Li dendrites and electrolyte leakage are common causes of Li-ion battery failure. H2, generated by Li dendrites, and electrolyte vapors have been regarded as gas markers of the early safety warning of Li-ion batteries. SnO2-based gas sensors, widely used for a variety of applications, are promising for the early safety detection of Li-ion batteries, which are necessary and urgently required for the development of Li-ion battery systems. However, the traditional SnO2 sensor, with a single signal, cannot demonstrate intelligent multi-gas recognition. Here, a single dual-mode (direct and alternating current modes) SnO2 sensor demonstrates clear discrimination of electrolyte vapors and H2, released in different states of Li-ion batteries, together with principal component analysis (PCA) analysis. This work provides insight into the intelligent technology of single gas sensors.

Understanding How Organosilicon Additives Delay Electrolyte Decomposition on LiNi0.8Mn0.1Co0.1O2 (NMC 811) Cathodes Using in Situ Techniques

Cathode materials such as LiNi0.8Mn0.1Co0.1O2 (NMC811) are of great interest for Li-ion battery (LIB) systems. By increasing the Ni content, the price decreases since Co is an expensive transition metal. In addition, NMC811 offers higher capacity and operating at high voltages, compared to other cathode materials (i.e., LCO, LMO, etc.). However, this cathode material suffers degradation from different sources. One of the main detrimental processes is oxygen loss from the lattice, which can cause decomposition of electrolyte components such as cyclic carbonates and further generate undesirable gassing in LIB systems. Several different organosilicon (OS) compounds have been reported to decrease gassing during storage with NMC622/Gr multi-layer pouch cells. Besides reducing gassing, OS compounds have been reported to increase the thermal stability of PF6 - and reduce HF, which is detrimental for LIB systems. Currently, the exact mechanism for how OS additives alleviate these undesired electrolyte degradation reactions is not well known. In this study we performed a mechanistic investigation on the effects of OS3 (organosilicon additive) during Li the intercalation/deintercalation processes on NMC811. First, we explored how OS3 affects the electron transfer kinetics by performing variable scan rate cyclic voltammetry. Second, we studied the mass accumulated on NMC811 surfaces during the first cycle as a function of applied potential using in situ electrochemical quartz crystal microbalance (EQCM). Finally, we analyzed the chemical composition of the cathode surface layer and how it evolves as a function of potential using in situ attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) at stepwise points during the first cycle. Together, these techniques provide a comprehensive study of the reactions occurring at the NMC811 electrode surface during the first cycle, including lithium intercalation kinetics, mass deposition and dissolution, and the chemical composition of surface decomposition species as a function of potential, it was found that OS3 delays the onset of mass accumulation and therefore delays electrolyte degradation during the first cycle on NMC811 cathode materials as confirmed by the presence of new absorbance features on in situ ATR-FTIR. We successfully identified a potential mechanism of action of how organosilicon additives help to prevent the carbonate-based electrolyte to decompose on NMC811 surfaces. These studies further provide new insights into the mechanisms of performance enhancement observed with OS additives.

(Invited) Synchrotron X-Ray Nano-Tomography and Multimodal Studies of Li-Ion Batteries

As batteries revolutionize all technological areas – from miniaturized electronic devices to electric vehicles and to large-scale energy storage, understanding the complex morphological, chemical and structural evolution and their interplays has been at the forefront of the research. Synchrotron X-ray characterization techniques provide insights into the electrochemical reactions and multiscale, multiphysics environments to address the fundamental mechanisms in these systems. The presentation will highlight the application of synchrotron X-ray analysis in two Li-ion battery systems, including both aqueous and non-aqueous systems. X-ray nano-tomography via transmission X-ray microscopy and spectroscopic imaging, complemented by other diffraction, spectroscopy and microscopy techniques, will be discussed. We will present how synchrotron X-ray nano-tomography and quantitative 3D morphological analysis were instrumental in revealing the dimensionality effect of conductive carbon fillers in LiNi 1/3Mn1/3Co1/3O2 (NMC111) cathode [1]. Additionally, we will discuss how a multimodal characterization approach offered insights when probing kinetics of water-in-salt aqueous batteries with thick, porous LiV3O8-LiMn2O4 electrodes [2, 3]. Through the morphological and chemical analyses, the work aims to facilitate the design of future advanced energy storage materials, as well as provide a novel characterization framework for studying a wider range of electrochemical systems.

Observation and Mitigation of Beam Damage Effects on the in Situ Experiment of Li-Ion Battery Cathodes: A Transmission X-Ray Microscopy Study

Advanced characterizations play critical roles in understanding the fundamental properties of important materials. For accurate characterization, it is always necessary to address the possibility of probe-induced damage. A typical example is the successful application of cryo electron microscopy with low dose electron to characterize highly sensitive samples (ref1-3). Unfortunately, there have been very few studies on the effects of radiation damage on Li-ion battery systems caused by synchrotron x-ray beam. In this presentation, we provide direct evidence of synchrotron x-ray beam damage during in situ characterization of battery materials, observed by transmission x-ray microscopy (TXM). The unique capabilities of this technique in obtaining both morphological and chemical information enabled us to study the beam damage issue caused by x-ray. Li-rich Li1.2Ni0.13Mn0.54Co0.13O2 material was characterized in situ to study the redox reaction mechanism of this material. Beam damage in the form of bubble formation in the liquid electrolyte was observed when the material was irradiated with x-ray during 2D/3D XANES (x-ray absorption near edge structure) image collection at Ni K-edge. The bubble formation in liquid electrolyte is most likely due to the decomposition of the electrolyte triggered by x-ray irradiation. This suggests beam damage issue needs to be considered not only for TXM which is commonly used to study the depth-dependent redox reaction in individual particles, but also spectroscopic techniques that employ similar energy range. Such damage may be related to the huge x-ray flux used in the in situ experiment. When filters were used to reduce the flux, the bubble formation was significantly reduced. We further show the evolution of the Ni redox during the cycling with suppressed beam damage, which should be more faithfully reflecting the situation. Acknowledgement This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Vehicle Technology Office of the US Department of Energy (DOE) through the Advanced Battery Materials Research (BMR) Program, including Battery500 Consortium under contract no. DE-SC0012704. This research used beamline 18-ID of the National Synchrotron Light Source II, a US DOE Office of Science user facility operated for the DOE Office of Science by Brookhaven National Laboratory under contract no. DE-SC0012704. References J. Z. Chen et al., J. Struct. Biol., 161, 92–100 (2008).X. Wang, Y. Li, and Y. S. Meng, Joule, 2, 2225–2234 (2018).X. Wang et al., Nano Lett., 17, 7606–7612 (2017).

Electrochemical Characteristics of Composite Solid Polymer Electrolytes Containing 1-Dimensional Active Ceramic Filler for All-Solid-State Lithium-Ion Batteries

Recently, the battery market for electric vehicle (EV) and energy storage system (ESS) is expanding. In addition, attempts and studies to implement a high energy density by applying a lithium metal anode to a Li-ion battery (LIB) system are in progress. However, the conventional organic liquid electrolytes have safety problems, such as a short circuit due to lithium dendrite growth, and a risk of ignition and explosion due to electrolyte leakage. To address the issues, all-solid-state batteries (ASSBs) using stable solid electrolytes have attracted much attention as new-generation batteries. Among solid electrolytes, composite solid polymer electrolyte (CSPE) has excellent merits over existing liquid electrolytes such as no electrolyte leakage, non-flammability, and a wide electrochemical potential window. In addition, various types of inorganic fillers may be introduced to improve electrochemical properties of CSPEs. In this study, the CSPEs were fabricated by incorporating 1D or OD Li0.33La0.557Ti0.99Al0.01O3 (A-LLTO) perovskite solid electrolyte fillers in a PVDF-HFP polymer matrix and their electrochemical properties were investigated. The optimized 1D A-LLTO containing CSPE (1D A-LLTO CSPE) exhibited a high ionic conductivity of 0.21 mS cm-1, a good potential stability of up to 4.87 V for Li/Li+, and a lithium ion transport number of 0.499 at 50 °C. In addition, 1D A-LLTO CSPE showed better thermal stability and electrochemical properties compared with 0D A-LLTO CSPE. The 1D A-LLTO CSPE exhibited a reduced overpotential of about 45 mV for 1000 h in contact with lithium metal at 50 °C. Furthermore, the Li/1D A-LLTO CSPE/NCM622 full cell exhibited satisfactory rate capability, cycling stability with a discharge capacity of 159.95 mAh g-1 and a coulombic efficiency of 97.6% over 100 cycles at a rate of 0.2 C, and performed stable long-term cycling performance at the rate of 0.5 C over 400 cycles at 50 ℃. These results demonstrate that the 1D A-LLTO CSPE is expected to become one of the hopeful candidates for ASSBs.

Rethinking residential energy storage: GHG minimization potential of a Carbon Reinforced Concrete facade with function integrated supercapacitors

With the rise of sustainable energy generation, the need for integrated building energy storage solutions increases. Supercapacitors have not yet been considered a viable alternative to Li-ion batteries, often because of their space requirements. We present the function integration of supercapacitors into a facade, where space is abundant when using novel lightweight Carbon Reinforced Concrete (CRC) construction designs. We develop real prototypes. While materials and processes for the approach have been characterized for manufacturability in earlier studies, the resulting sustainability potential remains an open question. This study therefore assesses and supports the design process of that multifunctional facade with the help of Life Cycle Assessment (LCA). LCA results shall guide design choices on materials and constructional alternatives. We further elaborate on the potential of the multifunctional facade to compete with a Li-ion battery system as the current benchmark for residential energy storage. While the proposed design is still a prototype, the cradle-to-site LCA models a full-scale production to allow for that comparability. We calculate the greenhouse gas (GHG) minimization potential for the multifunctional facade with integrated supercapacitors. It is significantly lower by a factor of around 20 in comparison to Li-ion battery energy storage. We further use different functional units to interpret the LCA results, considering both the function of the facade and energy storage. Overall, results show that the choice of the functional unit affects the material and constructional recommendations.

How the Sodium Cations in Anode Affect the Performance of a Lithium-ion Battery

Large cations such as potassium ion (K+) and sodium ion (Na+) could be introduced into the lithium-ion (Li-ion) battery system during material synthesis or battery assembly. However, the effect of these cations on charge storage or electrochemical performance has not been fully understood. In this study, sodium ion was taken as an example and introduced into the lithium titanium oxide (LTO) anode through the carboxymethyl cellulose (CMC) binder. After the charge/discharge cycles, these ions doped into the LTO lattice and improved both the lithium-ion diffusivity and the electronic conductivity of the anode. The sodium ion’s high concentration (>12.9%), however, resulted in internal doping of Na+ into the LTO lattice, which retarded the transfer of lithium ions due to repulsion and physical blocking. The systematic study presented here shows that large cations with an appropriate concentration in the electrode would be beneficial to the electrochemical performance of the Li-ion battery.

High-Pressure PEMWE Stack and System Characterization

As the urgency to decarbonize the industry and transport sector intensifies, renewable energy-based hydrogen production via advanced low temperature water electrolysis is attracting increased interest. Proton exchange membrane water electrolysers (PEMWE) offer several benefits over the more mature alkaline water electrolysis technology, including its load-following capability and the ability to operate at higher pressures. The latter is important because significant benefits can be harvested by adopting systems operating at pressure-levels compatible with the end use applications and thereby render the mechanical compressor redundant. At IFE we have developed a methodology which encompasses detailed energy- and techno-economic calculations of high-pressure systems, and a comparison between high-pressure electrolysis and state-of-the-art electrolysis at 30 bar in combination with a compressor has been carried out. Here, direct pressurization to 80 and 200 bar (relevant for, e.g., methanol and ammonia production) was found to be economically viable.To realize high-pressure H2 generation systems, many challenges related to system operability, efficiency and safety needs to be addressed. As part of the national infrastructure “The Norwegian Fuel Cell and Hydrogen Centre”, Institute for Energy Technology (IFE) has installed a flexible PEM water electrolyzer system platform for testing of small-scale prototype electrolyzers up to 33 kW and 200 bar differential pressure. The test rig is integrated with a sophisticated power conditioning system which consists of three custom-built DC/DC-converters (for PEMWE, PEMFC, and Li-ion battery systems), all coupled to the same DC-bus. This configuration makes it possible to test different hybrid electric topologies and to emulate different loads (e.g., grid load profiles, wind generation). This one-of-a-kind high-pressure PEMWE test facility at IFE is well suited to study performances of next-generation PEMWE stacks and systems, and to tailor and test control strategies that safeguards the system and maximizes efficiency and durabilityThe test rig has been commissioned with a prototype high-pressure stack with a production capacity of 2 Nm3/h (Nel Hydrogen), and the identified economically viable pressure range of 80-200 bar has been the main target for an experimental test campaign. The experimental results are presented from stack testing including polarization curves and EIS data as a function of temperature, pressure and current density. The results are discussed in relation to the techno-economic model, in order to identify pathways towards more efficient hydrogen production. Figure 1

Correlative Electrochemical-TEM Study: Probing the Pt Stability of Mesoporous N-Doped Carbon Supported Pt Nanoparticle ORR Electrocatalyst

In recent years, hydrogen proton exchange membrane fuel cells have gained growing attention in the heavy duty vehicle (HDV) sector due to lower cost with increased driving range and lower refueling time compared to Li ion battery systems.[1] However, special requirements apply to HDV fuel cells such as long lifetime (25000 – 30000 h) at low Platinum loadings. Additionally, future Pt cathode loadings should be reduced from ≥ 0.4 mgPt/cm² (i.e. the current benchmark) to 0.25 mgPt/cm² by 2050, while a constant power density of 840 mW/cm² at 0.769 V should be achieved as defined by the US Department of Energy.[2]Despite Pt nanoparticles finely dispersed on carbon supports are considered the benchmark catalysts, the cathode is yet suffering from several degradation processes such as carbon corrosion, Pt nanoparticle detachment, agglomeration, dissolution and Pt redeposition, hindering the achievement of the aforementioned goals.[3, 4] Therefore, in-depth understanding of the electrocatalyst degradation mechanisms by which Pt losses its catalytic activity is required to develop optimized synthesis methods for stable materials. Recently, we developed novel mesoporous N-doped carbon (MPNC) supports with improved stability against carbon corrosion in comparison to a commercial reference carbon support.[5] Utilizing the advantage of such enhanced stability, we designed Pt/MPNC catalysts for oxygen reduction reaction (ORR) with an extended stability reaching over 10000 cycles in comparison to the commercial Pt/C catalyst, as revealed by the accelerated stress tests (AST) in acidic media and within the carbon corrosion potential range between 1 V and 1.5 V vs RHE.In the present study, we synthesized Pt/MPNC-T catalysts under different reduction temperatures to control the Pt nanoparticle size distribution. We then investigated the impact of the various sizes of the Pt nanoparticles on the stability of Pt/MPNC-T after AST cycles. Therefore, Rotating disc electrode measurements with an established Pt AST protocol using a square wave potential between 0.6 V and 0.95 V vs. RHE over 30000 cycles was applied.[1] The ORR activity, the electrochemical active surface area by HUPD and CO stripping experiments were measured at the beginning of the cycle life test, then after 10000 AST cycles and finally after 30000 AST cycles. The electrochemical measurements before and after AST of the Pt/MPNC-T catalysts were correlated with ex-situ TEM and aberration corrected (AC) STEM data. Experimentally, lower reduction temperature synthesis leads to broader Pt size distributions. Thereby, we noticed the presence of Pt nanoparticles with a diameter between 1 and 3 nm, and smaller Pt entities such as Pt atom clusters and single sites of Pt (i.e. Pt single atoms) at the beginning of cycling. By imaging the surface after 30000 AST cycles, the Pt nanoparticle size substantially increased and the amount of smaller Pt entities was drastically reduced. Such findings indicate that the major degradation process follows the Ostwald ripening mechanism.In conclusion such results reveal the importance of determining the structure-function correlations, which contributes to the general understanding of catalyst degradation processes and allows a knowledge-based optimization of these Pt/MPNC materials in future works.

A second nearest-neighbor modified embedded-atom method combined with a charge equilibration interatomic potential for the Li–Ni–O ternary system and Li diffusion in lithium-ion battery cathode structure

Ni is a key element, especially in layered cathodes, to achieve a large capacity and a reduced cost. To analyze and gain insight into such cathode materials, large-scale atomistic simulations such as molecular dynamics (MD) are a suitable method. In this paper, a Li–Ni–O interatomic potential has been developed on the basis of the second nearest-neighbor modified embedded-atom method (2NNMEAM) formalism combined with a charge equilibration (Qeq) concept. This potential reproduces fundamental properties (thermodynamic, structural, elastic) of lithium-nickel and nickel oxide binary systems as well as the lithium-nickel oxide ternary system in good agreement with experiments and first-principles calculations. Lithium diffusion properties such as the activation energy for lithium migration and diffusion coefficients in Li1-xNiO2 layered structures are also calculated by a MD simulation and found to show the same tendency as observed in experiments. The potential can be utilized for simulating various material phenomena in the Li-ion battery (LIB) system and can be easily extended to the mainly used Li-[Ni,Mn,Co]-O quinary system, in combination with already developed Li–Mn–O and Li–Co–O ternary potentials based on the same formalism.

Fast capacity estimation for lithium-ion battery based on online identification of low-frequency electrochemical impedance spectroscopy and Gaussian process regression

Accurate capacity estimation is critical to improving the safety and reliability of lithium-ion (Li-ion) battery systems. Traditional capacity estimation mainly extracts capacity-related features by passively collecting the battery voltage, current, and temperature signals, which requires high integrity and regularity of charging curves. In this paper, six health indicators (HIs) are extracted through the online identification of Low-frequency electrochemical impedance spectroscopy (LEIS) by step wave, combined with Gaussian process regression (GPR) to achieve a fast capacity estimation for Li-ion batteries. The step wave is injected into the battery system during the charging process through BMS and bi-directional converter cooperation. Compared with square and multi-sine waves, the stress and response of each frequency step wave are equivalent to that of the sine wave. Moreover, HIs are resolved from the actual Warburg impedance angle instead of the empirical angle π/4. Three novel HIs related to the Li-ion diffusion coefficient are proposed: Warburg factor Wd, pseudo-Li-ion diffusion state PLDS and residual signal of empirical mode decomposition PLDSr. The volume of GPR training data is only 34% of the whole frequency band EIS data. The results show that the identified LEIS achieves 0.96 goodness-of-fit (R2) at the minimum sampling frequency of 50 Hz, and the novel HIs significantly improve the state of health (SOH) estimation accuracy with R2 above 0.95, root mean squared error below 1%, and mean absolute percentage error of about 0.9%. This method is an effective way to the active SOH detection for Li-ion battery, which is vital for the online SOH evaluation and early safety warning.

A Strategic Pathway from Cell to Pack-Level Battery Lifetime Model Development

The automotive energy storage market is currently dominated by the existing Li-ion technologies that are likely to continue in the future. Thus, the on-road electric (and hybrid) vehicles running on the Li-ion battery systems require critical diagnosis considering crucial battery aging. This work aims to provide a guideline for pack-level lifetime model development that could facilitate battery maintenance, ensuring a safe and reliable operational lifespan. The first of the twofold approach is a cell-level empirical lifetime model that is developed from a lab-level aging dataset of commercial LTO cells. The model is validated with an exhaustive sub-urban realistic driving cycle yielding a root-mean-square error of 0.45. The model is then extended to a 144S1P modular architecture for pack-level simulation. The second step provides the pack electro-thermal simulation results that are upscaled from a cell-level and validated 1D electrical model coupled with a 3D thermal model. The combined simulation framework is online applicable and considers the relevant aspects into account in predicting the battery system’s lifetime that results in over 350,000 km of suburban driving. This robust tool is a collaborative research outcome from two Horizon2020 EU projects—GHOST and Vision xEV, showcasing outstanding cell-level battery modeling accuracies.

Research Trend in Rock Salt Structured High Entropy Cathode

Development of lithium-ion rechargeable batteries with high energy storage capability are required in timely manner. Recently, it has been experimentally and computationally proven that oxides with the disordered rock salt structure can be charged and discharged in the Li-ion battery system. In particular, the high entropy disordered rock salt cathode has unique structure property, where both Li-ion and transition metal are randomly located on the cation sites. Such disordering in metal sites can migrate the Li-ion in a percolating way albeit with sluggish kinetics. Therefore, the high entropy disordered rock salt structure has attracted great attention due to its high energy density and stable structure. In this paper, we introduce a simple and effective strategy in the selection of transition metals for high entropy cathodes to achieve desired electrochemical properties.

A Review of Mechanical and Chemical Sensors for Automotive Li-Ion Battery Systems.

The electrification of passenger cars is one of the most effective approaches to reduce noxious emissions in urban areas and, if the electricity is produced using renewable sources, to mitigate the global warming. This profound change of paradigm in the transport sector requires the use of Li-ion battery packages as energy storage systems to substitute conventional fossil fuels. An automotive battery package is a complex system that has to respect several constraints: high energy and power densities, long calendar and cycle lives, electrical and thermal safety, crash-worthiness, and recyclability. To comply with all these requirements, battery systems integrate a battery management system (BMS) connected to an complex network of electric and thermal sensors. On the other hand, since Li-ion cells can suffer from degradation phenomena with consequent generation of gaseous emissions or determine dimensional changes of the cell packaging, chemical and mechanical sensors should be integrated in modern automotive battery packages to guarantee the safe operation of the system. Mechanical and chemical sensors for automotive batteries require further developments to reach the requested robustness and reliability; in this review, an overview of the current state of art on such sensors will be proposed.

An Overview of Cyber-Physical Security of Battery Management Systems and Adoption of Blockchain Technology

Lithium-ion (Li-ion) batteries are a key energy storage component in various electrical and electronic systems, such as mobile phones and electric vehicles. A properly designed battery management system (BMS) is crucial to guarantee the safety, reliability, and optimal performance of the battery, as well as to interconnect the battery systems with each other and external systems through communication channels. However, security threats of the Li-ion battery systems are often overlooked by BMS developers in the design phase. The cybersecurity of BMSs is an essential factor to consider as more battery systems require internet connectivity for functionality, such as intelligent monitoring, control, and maintenance. This article discusses the overall security vulnerabilities from potential cyber-attacks and defense strategies, as well as the adoption of current blockchain technology in BMSs, which will be used as a cybersecurity baseline reference to BMS developers. The implementation of blockchain technology is promising to protect BMSs from malicious cyber-physical attacks and ensure the secure utilization of battery systems for numerous applications in cyber-physical environments.

Detailed characterization of particle emissions from battery fires

Lithium-ion (Li-ion) batteries that are becoming ubiquitous in various applications may be susceptible to thermal runaway when subjected to certain abuse factors. Fire ensuing from such a thermal runaway event results in significant release of gaseous and particle emissions that pose a critical safety risk to human health. This program was focused on performing detailed characterization of particle emissions from Li-ion battery systems that experience thermal runaway. Four identical lithium iron phosphate (LFP) modules and one nickel manganese cobalt oxide (NMC) module were each subjected to thermal runaway. Two LFP modules and the NMC module were triggered into runaway via nail-penetration, while the remaining two LFP modules were triggered into runaway via over-charging. Particle emissions were characterized in terms of particulate matter mass (PM2.5), real-time total (solid + volatile) and solid PN/size (5.6–560 nm), real-time black carbon, organic/elemental carbon partitioning and volatile fraction of PM2.5. Gaseous emissions were measured using a real-time Fourier Transform Infrared spectrometer. Results suggest that battery fires can result in significant particle and gaseous emissions that may be a function of initiation mechanism, battery chemistry, and cell arrangement within a module among other variables. LFP modules subjected to nail penetration yielded relatively less emissions as propagation was not observed. Over-charging LFP modules resulted in significant emissions that showed a continuous increase till peak levels were reached followed by a gradual decrease. PM2.5 emissions ∼380 g/h and total PN emissions ∼1.5E + 17 particles/h (or 1.3E07 part./cm3) were observed. Nail-penetration of the NMC module resulted in several distinct peaks due to propagation of runaway from cell-to-cell. This module resulted in the highest emission rates of 551 g/h of PM2.5 and 2.1E + 17 particles/h (or 1.9E07 part./cm3) of total PN.Copyright © 2022 American Association for Aerosol Research

On-site solar powered refueling stations for green hydrogen production and distribution: performances and costs

Today, the hydrogen is considered an essential element in speeding up the energy transition and generate important environmental benefits. Not all hydrogen is the same, though. The “green hydrogen”, which is produced using renewable energy and electrolysis to split water, is really and completely sustainable for stationary and mobile applications. This paper is focused on the techno-economic analysis of an on-site hydrogen refueling station (HRS) in which the green hydrogen production is assured by a PV plant that supplies electricity to an alkaline electrolyzer. The hydrogen is stored in low pressure tanks (200 bar) and then is compressed at 900 bar for refueling FCHVs by using the innovative technology of the ionic compressor. From technical point of view, the components of the HRS have been sized for assuring a maximum capacity of 450 kg/day. In particular, the PV plant (installed in the south of Italy) has a size of 8MWp and supplies an alkaline electrolyzer of 2.1 MW. A Li-ion battery system (size 3.5 MWh) is used to store the electricity surplus and the grid-connection of the PV plant allows to export the electricity excess that cannot be stored in the battery system. The economic analysis has been performed by estimating the levelized cost of hydrogen (LCOH) that is an important economic indicator based on the evaluation of investment, operational & maintenance and replacement costs. Results highlighted that the proposed on-site configuration in which the green hydrogen production is assured, is characterized by a LCOH of 10.71 €/kg.

Adaptive Integral Correction-Based State of Charge Estimation Strategy for Lithium-Ion Cells

Lithium-ion (Li-ion) battery systems are critical elements of future energy systems and electric vehicles. Accurate prediction of the state of charge (SoC) is necessary for the safe and reliable functioning of Li-ion battery systems. Achieving a precise SOC estimate is challenging due to the nonlinear characteristics and variations of model parameters caused over the cell lifetime. This paper introduces an adaptive estimation strategy that can compensate for the effect of cell degradation for achieving high accuracy SoC estimation. The proposed method uses an integral correction-based SoC estimation loop utilizing a Li-ion cell model. The effect of model parameter variation is corrected by introducing two additional correction factors, the cell model resistance, and capacity correction factor. These correction factors are employed to update the Li-ion cell model, resulting in an adaptive integral correction-based SoC estimation technique that can compensate for the influence of cyclic degradation-induced parameter change. The proposed method is validated through extensive simulations in the Matlab-Simulink environment, and its output is compared to the existing unscented Kalman filter-based SoC estimation method. The proposed estimation strategy can adapt to the cell circumstances and correct for model uncertainties. The results indicate that the proposed adaptive SoC estimation strategy provides more precise and accurate SoC estimates for the entire lifespan of the Li-ion cell.