Capacity Degradation Research Articles

Behavior of circular ultra-high-strength concrete-filled steel tube columns subjected to combined high-axial and cyclic lateral loads

The present study examined the seismic performance of circular concrete-filled steel tube (CFST) columns infilled with ultra-high-strength concrete (UHSC >100 MPa) as well as the beneficial effect of embedded spiral confining (SC) reinforcement at high axial load ratios (0.53–0.70) in order to enhance the safety and structural integrity of high-rise buildings. Seven specimens, including four CFST columns and three SC-CFST columns, were investigated under combined high axial and quasi-static cyclic lateral loads. The test parameters included axial load ratio (0.53–0.70), concrete compressive strength (64–111 MPa), embedded spiral confining reinforcement (pitch of 30 mm and 60 mm), and concrete vibration state. The test results demonstrated that adding spiral reinforcement improved the deformation capacity of CFST columns, which was reduced by the increased concrete strength. By embedding spiral confining reinforcement (volumetric ratio 3.3 %), the SC-CFST columns attained a deformation capacity comparable to that of CFST columns with normal concrete (64 MPa) for an axial load ratio of 0.53. The higher axial load ratio and concrete strength of composite columns led to a significant P-Delta moment effect, resulting in a substantial drop in columns' lateral load capacity. Composite columns with UHSC showed a larger contribution from the column base rotation to the specimen's lateral deformation when compared to composite columns with normal-strength concrete because the rigidity offered by UHSC made the column more rigid and reduced its flexural deformation. The unvibrated core concrete of the CFST column did not influence the initial stiffness and energy dissipation capacity. However, during the later stages of loading, the damage in core concrete rapidly accumulated, resulting in instant degradation of the load capacity and stiffness, considerable axial shortening, and poor deformation capacity. The experimental investigation offered a reliable reference on the performance of CFST columns constructed under high-axial load ratios (0.53–0.7) using ultra-high-strength concrete (>100 MPa) and spiral confining reinforcement so as to promote their application in practical engineering.

Damage quantification based on drift ratios and axial capacity degradation for RC columns under low-velocity impact loads

Damage determination and quantification are critical issues in conducting damage assessment and performance-based design for RC columns under low-velocity impact loads. An impediment in these issues lies in defining reasonable damage criteria. To this end, a framework inspired by existing experimental results is proposed to quantify the damage of RC columns. The core concept of this framework is to establish the relationship between the engineering demand parameter (i.e., drift ratio) and the damage index based on residual axial capacity and to convert the damage index threshold to the drift ratio threshold using a reliability-based method. According to the proposed framework, damage criteria are developed for RC columns in two typical impact scenarios, including the mid-span and near-base impacts. During this process, linear relationships between the maximum drift and the residual one at the impact location are developed by statistically analyzing the existing experimental data (a total of 212 test samples). Based on experimentally validated numerical models, empirical formulas for estimating the residual axial capacity of RC columns are established. The maximum drift, the residual drift, and the axial capacity degradation are interrelated in the proposed damage criteria, overcoming the limitation that the current deformation-based damage criteria used for low-velocity impact loads lack physical significance.

Manganese octahedral point-constructed oxygen defects realize highly stable lithium-rich cathode materials

Lithium-rich layered oxides (LLOs) are highly favored by researchers for their high specific capacity and low cost. However, the severe voltage and capacity degradation of the material have become the biggest obstacle to commercial application. In this work, the construction of oxygen vacancies on the surface of Li-rich cathode and SiO44- gradient doping have been used in Li-rich materials to improve its performance. The presence of oxygen defects in MnO6 octahedra stabilizes its structure and enhances the electrochemical activity of TM ions. This also serves to reduce the energy level and intensity of the unhybridized O 2p orbitals, as well as decrease the release of lattice oxygen. The "localization effect" of SiO44− on TM ions also inhibits their irreversible migration. After modification, the electrochemical performance of the material has been significantly improved. The initial Coulombic efficiency increased to 89.46 % (82.68 % for LLO), while the specific capacity discharge at 5C reached 178.8 mAh g−1 (139.2 mAh g−1 for LLO). Additionally, the capacity rate after 500 cycles at 1C was 74.1 % (54.5 % for LLO). Therefore, this work provides valuable insights for designing oxygen-deficient lithium-rich cathode materials.

Safety-enhanced battery modules with actively switchable cooling and anti-impact functions

In this paper, a magnetically controlled multifunctional smart material system based on magneto-sensitive shear thickening fluid (MSTF) is proposed for the safety-enhanced lithium-ion battery (LIB) modules. The rheological behavior of the MSTF can be intelligently manipulated by a magnetic field, allowing its function in the battery module to be actively and rapidly switched between cooling and impact resistance. To quantitatively assess the temperature control and impact resistance of the purposely prepared MSTF, comprehensive experiments are conducted to thoroughly analyze the thermal performance, mechanical response, and electrochemical performance of the battery module integrated with cooling and active impact protection. The results of the cooling test show that the water-based MSTF without a magnetic field has a flowability that gives it similar temperature control to that of a commonly used coolant (water). This suggests that the MSTF can be an effective cooling medium for rapid cooling of LIBs. The results of the impact test indicate that MSTF in a magnetic field can completely avoid battery deformation and significantly reduce the impact force applied to the LIB during impact, due to the fact that the magnetic field can quickly transform the MSTF into a solid-like state, which gives it a significant anti-impact effect. More importantly, the LIBs protected by the MSTF exhibit no rapid capacity degradation or abnormal temperature increase in the subsequent electrochemical cycling tests, while the unprotected or weakly protected LIBs compromise after the impact. With the MSTF, excellent cooling and anti-impact functions can be actively switched in one system, and this innovative integrated design is expected to drive significant advances in safety for battery modules.

Cracks in Polycrystalline Li(NiMnCo)O2 Particles Enable Rapid Discharging of Li-Ion Batteries

The degradation of capacity in Li-ion batteries during charging and discharging cycles has been a persistent challenge in advancing battery lifetime. Among the commonly accepted causes of capacity degradation is the formation of cracking along the grain boundaries of polycrystalline NMC particles. These cracks are known to occur from the anisotropic expansion and contraction of the crystal lattice induced by the (de)intercalation of lithium.To address this issue, single crystalline NMC particles were introduced, lacking grain boundaries and seemingly less prone to developing cracks. batteries utilizing single crystalline particles exhibited improved capacity retention. However, in terms of rapid charging and discharging, these single particle batteries experienced a sudden increase in overpotential compared to polycrystalline particle batteries. Yet, a clear explanation for this abrupt rise in overpotential during rapid charging and discharging in single crystalline particle batteries has remained elusive.In this study, we investigated the rate-capability of individual single and polycrystalline NMC particles using an innovative high-throughput single-particle electrochemistry platform. Based on our rate-capability findings, we argue that the cracks, previously identified as a factor contributing to capacity degradation, are actually a crucial element enabling rapid charging and discharging in polycrystalline particles.

A Thermal Tanks-in-Series Model for Simulating over-Discharge Cycling in Lithium-Ion Batteries

Energy storage will play a crucial role in the transition to clean and renewable sources of energy production to meet future consumption demands.1 Lithium-ion (Li-ion) batteries are widely adopted due to their high energy density, low self-discharge rate and fast charging capabilities for applications like electric vehicles and grid storage.2 Li-ion batteries for high voltage operations, where several cells are connected in series, can experience inadvertent over-discharge due to differences between cells3,4. These differences can arise due to many reasons including changes in internal resistance and deviation in electrochemical degradation that can cause divergence of cell open circuit potentials. Over-discharge is a condition when the manufacturer recommended lower voltage limit is crossed while discharging4, which results in various side effects such as electrolyte decomposition, capacity degradation, cathode morphology change and possible internal short circuit3,5. Increase in anode potential during over-discharge leads to copper dissolution from the anode current collector and subsequent plating within cell components. The Solid Electrolyte Interface (SEI) can decompose during excessive deintercalation and reform during charging, reducing the lithium inventory. Excessive heat generation during cycle life testing after occurrences of over-discharges has been found in some cases to lead to temperatures >150 °C6,7.Temperature plays a key role in the electrochemical performance of individual cells, affecting the diffusivities of ions, kinetics of reactions and rate of degradation of the battery. A physics-based modeling approach coupled with a thermal model can be employed to understand the effect of over-discharge on the electrochemical behavior of Li-ion batteries and provides insights into the interplay of various degradation mechanisms that cause capacity fade.The Thermal Tank-In-Series9,10(TTiS) model is a systematically volume-averaged form of the standard pseudo-2-dimensional (p2D)11 model with energy balance equations for the current collectors, cathode, separator and anode. This reduces the number of equations in the model and improves computational speed while maintaining accuracy, as it is sensitive to changes in the battery’s state of charge (SOC) and cell temperature, which helps predict the overpotential changes to the cell electrodes and thermodynamics.We use the TTiS model to identify the dominant fade mechanisms in 3 sets of experimental cycling and temperature data for the: i) normal operating window (2.5V – 4.2V), ii) 5 initial cycles of over-discharge (1.5V – 4.2V) followed by normal operation until 20% capacity fade and iii) 5 cycles of periodic over-discharge every 20 cycles, until 20% capacity fade. Analysis on the effect of C-rate, ambient temperature and voltage window of operation will facilitate understanding the temperature behavior and overpotentials in a cell sandwich. Key considerations required in extending a model to simulate over-discharge will also be examined. References S.P. S. Badwal, S. S. Giddey, C. Munnings, A. I. Bhatt, and A. F. Hollenkamp, Frontiers in Chemistry, 2, 28 (2014).G. Pistoia. Lithium-Ion Batteries: Advances and Applications. First ed. Elsevier, Amsterdam (2014).R. Guo, L. Lu., M. Ouyang, X. Feng. Sci Rep 6, 30248 (2016).G.Zhang, X. Wei, S. Chen, J. Zhu, G. Han, and H. Dai. J. Power Sources, 521, 230990. (2022).C. Fear, D. Juarez-Robles, J. A. Jeevarajan, and P. P. Mukherjee, J. Electrochem. Soc., 165, A1639–A1647 (2018).D. Juarez-Robles, Purdue Univ. Ph.D. Thesis (2019).H. Maleki and J. N. Howard, J. Power Sources, 160, 1395–1402 (2006).H. Liu, Z. Wei, W. He, and J. Zhao, Energy Convers. Manag., 150, 304–330 (2017).A. Subramaniam, S. Kolluri, S. Santhanagopalan, and V. R. Subramanian, J. Electrochem. Soc., 167, 113506 (2020).A. Subramaniam, S. Kolluri, C. D. Parke, M. Pathak, S. Santhanagopalan, and V. R. Subramanian, J. Electrochem. Soc., 167, 013534 (2020).M. Doyle, T. F. Fuller, and J. Newman, J. Electrochem. Soc., 140, 1526 (1993)

Scaling and Commercializing Continuous Supercritical Hydrothermal Single Crystal Cathode Active Material Manufacturing

Current polycrystalline cathode active materials (CAMs) in the market face a significant challenge during charge-discharge cycles. The lithiation and de-lithiation processes induce volume changes within the CAMs, leading to strain along grain boundaries. This strain, arising from the expansion of crystals in different orientations, often results in material pulverization, creating void fractions. Such deterioration leads to increased impedance, capacity degradation, and shorter cycle life.Addressing these challenges, there is an emerging demand for single crystal (SC) CAMs, which promise enhanced performance by eliminating internal void fractions and grain boundaries. The continuous supercritical hydrothermal process, invented at Argonne National Laboratory, offers an innovative and cost-effective method to produce SC CAMs. This method effectively reduces energy consumption and production costs, while also lowering carbon emissions.In this presentation, we provide a comprehensive overview of the advancements in scaling up and commercializing continuous supercritical hydrothermal process for SC CAM manufacturing. Our focus is on the efforts undertaken by ACT-ion Battery Technologies, the industry commercialization partner, highlighting the significant strides made towards implementing this promising solution on a practical level.

Unravelling the Effect of Sodium Doping on Li2MnO3 nanostructured Cathode Materials

The quest to develop affordable, high-performance electrode materials for lithium-ion batteries in electric vehicles is driving scientific innovation forward. Li2MnO3, as a prospective high-capacity (459 mAh.g-1) cathode, suffers from capacity degradation and voltage decay during the cycling process. Nanostructuring and incorporating sodium ions into lithium sites can mitigate voltage decay by limiting transition metal migration, impeding oxygen loss, and improving lithium diffusion by lowering the activation energy of Li-rich layered host materials. Herein, sodium-incorporated nonospherical structures of the form Li2-xNaxMnO3 (0 ≤ x ≤ 2), generated through the amorphisation and recrystallisation (A+R) technique show remarkable structural stability and enhanced Li-ion mobility owing to the enlarged lithium lattice upon sodium entrance. Specifically, the Li1.95Na0.05NaO3 nanosphere, displays more stable Li+/Mn4+ layers which will greatly contribute to its capacity. The microstructures associated with this configuration show well-ordered layers with high lithium kinetics and lower activation energy compared to pristine Li2MnO3. Characterisation of the x-ray diffraction (XRD) patterns revealed peak broadening along with the shifting of peaks at 2Θ~38 to the right due to the enlarged lithium layers occupied by sodium ions to facilitate lithium diffusion. Moreover, the undesired phase transformation from layered to spinel was observed at a later stage of charge for the sodium-doped systems, suggesting that the presence of sodium stabilizes the structure and minimizes the migration of manganese into lithium layers. These findings may lead to solutions for problems such as structural instability, lattice oxygen loss, and capacity decay in layered lithium oxide materials.

Boosting polysulfides conversion kinetics through heterostructure optimization and electrons redistribution for robust lithium-sulfur batteries

Lithium-sulfur batteries (LSBs) are gaining significant attention as a promising candidate to satisfy the demand for high energy density. However, their application is still hindered by the notorious shuttle effect of intermediate polysulfides and the sluggish redox kinetics. Herein, we provide an electrocatalyst composed of two-dimensional (2D) bimetallic sulfides with layered cross-linking structure evenly distributed on 2D MXene nanosheets substrates (Bi2S3/MoS2@MX). Composition optimization and rational structural design effectively mitigate the self-stacking defect and expand the exposure of active sites. The electrons redistribution at heterogeneous interfaces generates a built-in electric field, thereby promoting electron transfer efficiency. Experiments and theoretical calculations results confirmed that the synergistic effect of heterostructures can effectively strengthen the adsorption and conversion of polysulfides, thereby significantly mitigating the shuttle effect. The utilization of sulfur is improved, and the corrosion degree of lithium metal anode is reduced. Consequently, the LSBs assembled with Bi2S3/MoS2@MX modified separator manifest an impressive initial specific capacity of 1306 mAh g−1 at 0.2C. Remarkably, the battery exhibits good long-term cycling stability with only 0.069 % capacity degradation per cycle at 2C after 500 cycles. This work demonstrates that synergistic cooperation of diverse catalytic materials represents an effective strategy for enhancing the potential for industrial application of LSBs.

(Invited) Revolving the Mechanical Stress in Batteries by Using Microcantilever

Although the generation of mechanical stress in the anode material is suggested as a possible reason for electrode degradation and fading of storage capacity in batteries, only limited knowledge of the electrode stress and its evolution is available at present. Here, we show real-time monitoring of the interfacial stress of a few-layer MoS2 system under the sodiation/desodiation process using microcantilever electrodes. During the first sodiation with a voltage plateau of 1.0 to 0.85 V, the MoS2 exhibits a compressive stress (2.1 Nm−1), which is substantially smaller than that measured (9.8 Nm−1) during subsequent plateaus at 0.85 to 0.4 V due to the differential volume expansion of the MoS2 film. The conversion reaction to Mo below 0.1 V generates an anomalous compressive stress of 43 Nm−1 with detrimental effects. These results also suggest the existence of a separate discharge stage between 0.6 and 0.1 V, where the generated stress is only approximately one-third of that observed below 0.1 V. This approach can be adapted to help resolve the localized stress in a wide range of electrode materials, to gain additional insights into mechanical effects of charge storage, and for long-lifetime battery design.

Characterization of Degradation Mechanisms of Alternative Electrolytes Solutions in Fast Charging Li-Ion Batteries

While the idea that fast charging batteries could be utilized in electric vehicles is enticing, current fast charging batteries face significant challenges that must be mitigated before this application is realized. Fast charging batteries currently suffer from capacity loss and degradation over time which not only affects battery life but poses a safety hazard. The current electrolyte, 1.2 M LiPF6 in 3:7 wt.% EC/EMC (Gen2), contains the salt LiPF6 that when exposed to moisture can form dangerous hydrofluoric acid and contains a carbonate-based solvent that when exposed to oxygen can ignite. In addition, batteries experience degradation over many cycles of fast charging which results in capacity fade and poor battery performance. However, previous studies have shown the potential for other electrolyte systems to mitigate these problems, specifically by using highly concentrated electrolytes1. These studies claim that using these electrolytes results in the formation of a solid electrolyte interphase (SEI) that passivates Li ions better than the Gen2 electrolyte. The SEI is a layer that forms on the anode within the battery and serves as a protective layer that allows for Li intercalation into graphite and can therefore protect against degradation. By using different electrolytes, a different SEI is formed, and different degradation mechanisms are observed. In this way, the SEI can be tuned to improve Li passivation and ionic conductivity by changing the electrolyte’s composition and concentration2. This research focuses on such alternative electrolyte systems and aims to characterize the different degradation mechanisms corresponding to each electrolyte. Favorable performance has been observed using 1.2 M LiFSI in 3:7 wt.% EC/EMC as an electrolyte. We are studying LiFSI in acetonitrile (AN) at higher concentrations than traditional Gen2 to quantify the SEI. We expect AN to form an anion derived SEI, a composition of which results in improved passivation of Li ions1. In this study, we characterize degradation of alternative electrolyte systems through x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). Through these methods we can observe and quantify both crystalline, amorphous degradation products due to loss of Li inventory and loss of active material. XPS allows quantification of compositional changes in the SEI layer at the surface of the electrode. The SEM provides qualitative information on degradation such as visualizing lithium plating and dendrite formation. We implement quantitative XRD to measure the crystalline phases of the graphite anode, showing the degree of lithium intercalation and further quantifying degradation such as Li plating. Putting the results of these three characterization techniques together in tandem with electrochemical cycling data paints a picture of the degradation that happens on the anode of a fast-charging lithium-ion battery with respect to electrolyte composition.[1] Yamada, Y., Wang, J., Ko, S., Watanabe, E., & Yamada, A. (2019). Advances and issues in developing salt-concentrated battery electrolytes. Nature Energy. [2] Logan, E. R., & Dahn, J. R. (2020). Electrolyte Design for Fast-Charging Li-ion Batteries. Trends in Chemistry.

Li-Ion Intercalating Cathode for Advanced Lithium-Sulfur Batteries

The advancement of lithium-sulfur (Li-S) batteries represents a significant shift in high-energy-density electrochemical storage, offering energy densities far exceeding those of traditional lithium-ion systems. This research contributes to the evolving field of Li-S batteries by proposing a novel strategy to optimize cathode performance, crucial in harnessing their full potential.Li-S batteries are characterized by their unique electrochemical process, which involves converting elemental sulfur to lithium sulfide (Li2S) during discharge via lithium polysulfide intermediates. A traditional challenge in this process is the notorious shuttle effect caused by lithium polysulfide intermediates. These intermediates, highly soluble in standard electrolytes, migrate continuously between the cathode and anode, leading to substantial active material loss, rapid capacity degradation, and reduced coulombic efficiency. Significant advancements have been made by introducing metal compounds with a chemical affinity for lithium polysulfides. However, a persistent challenge remains: the insulating nature of Li2S, which hinders electron transport. Recent strategies aiming to address these issues have focused on electrolytes with enhanced Li2S solubility to promote three-dimensional (3D) Li2S growth and prevent cathode passivation. Yet, the increased reactivity of such electrolytes poses new challenges, highlighting the need for alternative solutions.Our study explores this challenge, utilizing lithiated metal oxides as intercalating cathode materials to control Li2S growth dynamics. This method offers immediate mitigation of side reactions in the implementation of enhanced electrolytes. The scope of our research encompasses the thorough synthesis and characterization of these intercalating oxides, emphasizing their role in control Li2S growth. Additionally, we delve into the electrochemical characterization of these materials, focusing on their lithiation/delithiation kinetics and the consequent impact on Li-S battery performance. These intercalating oxides, capable of incorporating lithium ions within their crystal structure, present a promising path for aligning lithiation with Li2S formation, thereby fostering effective 3D growth. This contrasts with other oxides where asynchronous lithiation results in conventional two-dimensional (2D) Li2S growth, leading to premature discharge termination and suboptimal battery performance.We introduce a mechanism where 3D Li2S growth is driven by enhanced solvation of Li2S, intricately linked to the lithiation behavior of these oxides. By incorporating these optimized intercalating oxides in Li-S cells, we observe notable improvements in discharge capacity and sulfur utilization. This improvement is especially significant under high sulfur loading conditions, which typically exacerbate the polysulfide shuttle effect and pose formidable challenges for Li-S battery efficiency. Our investigation includes a detailed morphological analysis of Li2S deposition on various cathode surfaces. Employing advanced techniques like ex-situ Scanning Electron Microscopy (SEM) and electrodeposition modeling, we discern distinct Li2S growth patterns. These findings reveal that cathodes incorporating specific intercalating oxides exhibit reduced surface passivation due to predominant 3D Li2S growth, as opposed to the 2D growth observed in other oxide substrates. This variation in growth morphology significantly impacts cell performance, particularly under high sulfur loading conditions, where effective management of Li2S formation and polysulfide shuttling is crucial.In conclusion, this research marks a significant step in addressing the fundamental challenges of Li-S batteries. By leveraging the distinct properties of select intercalating oxides, the study not only deepens our understanding of Li2S growth mechanisms but also demonstrates an effective method to enhance Li-S battery performance. This work lays a foundation for future developments in high-energy-density battery technologies and signifies a crucial advancement towards the realization of more efficient and robust Li-S batteries.

Physics-Based State of Health Prediction of Lithium-Ion Battery during Fast Charging

Electrification of the transportation sector and increased use in consumer electronics have driven the increasing demand for lithium-ion batteries (LiBs) (1). Despite their high energy density and long service life, LiBs suffer from capacity degradation due to continuous growth of solid electrolyte interface (SEI) layer and plating of lithium on the anode surface. Graphite, the anode in most LiBs, has a high tendency to catalyze the degradation of the electrolyte consisting of LiPF6 and ethylene carbonate to form an SEI of Li-rich carbonate, phosphate, and fluoride compounds (2, 3). The SEI film grows during service due to the deposition of reaction products and repeated cycles of damage and reformation due to the contraction and expansion associated with volume changes during Li-ion intercalation and deintercalation. Additionally, fast or low-temperature charging of batteries results in lithium plating on the anode surface because the elevated concentration of Li+ on the anode surface results in graphite potential falling below 0V vs. Li+/Li and increased likelihood of Li deposition compared to intercalation (4). Lithium loss due to the side reactions of SEI growth and plating contributes to capacity loss and may increase the likelihood of battery failure. Hence, accurate modeling of the side reactions is required to determine the state of health (SOH) and predict the remaining capacity of LiBs during operation (5).We report an experimentally validated single particle model (SPM) to estimate the influence of SEI growth and Li plating on the capacity changes in Lithium Cobalt Oxide (LCO)/Carbon cells during repeated cycling (6-8). The SPM model idealizes each electrode as a single particle to approximate the cell response. A. Sarkar et al. (5) included the influence of SEI growth, plating, SEI fracture, and temperature in the SPM model to determine the influence of the side reactions on battery performance. The parameters corresponding to side reactions, such as the SEI film growth rate, conductivity of the SEI film, and reversibility of the plating reaction, were determined through comparison of numerical predictions of cell voltage and capacity change with experimental response measured at charging rates of 0.1C and fast charging rate of 2C on PowerStream 35 mAh LCO/C coin cells (Lir2032) as shown in Figure 1. In addition, the coin cells were subjected to charge/discharge experiments at charging rates varying from 0.1C – 5C for 100 cycles. Experimental measurements of the cell capacity changes were compared to model predictions for the different charging rates to validate the modeling assumptions and determine the efficacy of the estimated parameters in describing the cell degradation. The agreement between the model prediction and measured experimental response showed that the single particle model augmented with side reaction mechanisms can describe the cell degradation and is suitable for predicting the remaining capacity and safety of LiBs subjected to a range of charging rates. The model can also predict the accumulation of irreversibly plated lithium on the anode surface during repeated fast charging. The amount of plated lithium determines the severity of dendritic growth, and thus, model predictions of lithium accumulation may be used to estimate the likelihood of battery failure under fast charging conditions. Acknowledgment:This work was supported by the National Science Foundation, Iowa State University, and University of Connecticut.

Accurate prediction of electric vehicles mileage for proactive battery management in varied conditions using multi-criteria approach

This research addresses several critical challenges in managing battery aging within Electric Vehicles (EVs). Key challenges include minimizing capacity degradation while maximizing vehicle performance and accurately predicting State of Charge (SoC) under diverse operational conditions. Additionally, integrating factors such as vehicle and battery age, driving cycles, environmental conditions, and regional climate variations posed significant hurdles in achieving comprehensive battery management. To tackle these challenges, the research presents a novel framework integrating an advanced Multihead cross attention-based optimizer with a bidirectional long short-term memory network, further enhanced by the coati optimization algorithm. This innovative approach aims to improve prediction accuracy for critical battery performance metrics, such as SoC and battery lifetime. Implemented and rigorously evaluated using Python, the framework demonstrates a substantial 20% increase in battery performance through detailed SoC and temperature analysis, coupled with an impressive 40% enhancement in battery lifetime. These results highlight the ability to overcome previous challenges and provide robust solutions for effective battery management in real-world EV applications.

Reconstructing the Pseudo-2-Dimensional (p2D) Model in Comsol Multiphysics Using Mathematical Interfaces

The classic ‘pseudo-2-dimensional’ (p2D) model of Newman and co-workers (also known as the DFN model), with its different efficient implementations, is the state-of-the-art physics-based electrochemical model for lithium-ion batteries. COMSOL Multiphysics (COMSOL) is a popular modeling software for multiphysics simulations, and its Battery Design Module for Li-ion batteries is widely used in the battery modeling community. This work presents a step-wise model development for reconstructing the detailed p2D model equations. This includes variable model parameters and weak-form implementation for the solid-phase diffusion, eliminating the need for non-local couplings and approximations for modeling the pseudo radial-dimension in the solid-phase.To model and understand the effect of capacity degradation on lithium-ion cells, the battery models in COMSOL need to incorporate additional degradation mechanisms. In this work, we have followed the approach of equation-based modeling in COMSOL, which enables us to formulate the p2D model using the mathematical PDE interfaces. This approach provides us with a lot of flexibility in terms of battery degradation model formulation and helps develop a clearer understanding of the p2D model equation in light of the assumptions involved.The steps in the model development involved writing the conservation equations in the generic mathematics interfaces coupled with the additional equations for the degradation mechanisms. The efforts were centered on developing cycling simulations based on Events for practically relevant operating conditions. This custom model was validated against the results from COMSOL’s Battery Interface, in-house codes, and baseline cycle data from the experiments and further developed as a physicochemical degradation model for automotive, large-format Lithium-ion batteries.This equation-based COMSOL model with cycling works without the requirement for Battery Design Module, LiveLink and Application Builder and can be adopted for a variety of electrochemical modeling applications by the electrochemical modeling community.

(Invited) Deciphering the Interfacial Chemistry and Degradation Pathway of Layered Cathode Materials

Cathode materials such as layered oxides play a crucial role in determining batteries' energy density and safety. LiNixMnyCozO2 (NMC), as the dominating cathode, has been successfully commercialized for many years. In addition, there is a consensus that integrating NMC cathodes into all-solid-state batteries (ASSBs) is an effective way to achieve high energy densities. However, NMC cathodes are still facing many challenges, particularly, during the perusing of the high Ni concentration and high cut-off voltages. In the presentation, we will discuss the interface degradation of the NMC cathode at multiple length scales. By comprehensive imaging and spectroscopic techniques, we could bridge the degradation phenomenon from the electrode scale to the atomic scale. We will present the challenges of characterizing the surface properties of the cycled layered cathode and summarize our strategies that can enhance the surface stability of NMCs. Our fundamental understanding will inform the design principles at multiple length scales in batteries. Shifting our focus to solid-state batteries (SSBs), there is a growing body of research on SSBs incorporating NMC cathodes and argyrodite solid electrolytes (SEs). However, these advanced ASSBs face significant challenges in terms of low initial Coulombic efficiency and rapid capacity degradation. Therefore, we also try to understand the interfacial degradation mechanisms in composite SE-NMC cathodes in this talk.

Immobilization and Catalytic Conversion of Polysulfide by In-Situ Generated Nickel in Hollow Carbon Fibers for High-Rate Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries are considered promising energy-storage systems because of their high theoretical energy density, low cost, and eco-friendliness. However, problems such as the shuttle effect can result in the loss of active materials, poor cyclability, and rapid capacity degradation. The utilization of a structural configuration that enhances electrochemical performance via dual adsorption-catalysis strategies can overcome the limitations of Li-S batteries. In this study, an integrated interlayer structure, in which hollow carbon fibers (HCFs) were modified with in-situ-generated Ni nanoparticles, was prepared by scalable one-step carbonization. Highly hierarchically porous HCFs act as the carbon skeleton and provide a continuous three-dimensional conductive network that enhances ion/electron diffusion. Ni nanoparticles with superior anchoring and catalytic abilities can prevent the shuttle effect and increase the conversion rate, thereby promoting the electrochemical performance. This synergistic effect resulted in a high capacity retention of 582 mAh g-1 at 1 C after 100 cycles, providing an excellent rate capability of up to 3 C. The novel structure, wherein Ni nanoparticles are embedded in cotton-tissue-derived HCFs, provides a new avenue for enhancing electrochemical performance at high C rates. This results in a low-cost, sustainable, and high-performance hybrid material for the development of practical Li-S batteries.

Investigation the behavior of LWAC encased steel columns after exposure to elevated temperature

AbstractThis paper presents experimental and numerical investigations on the behavior of eccentrically loaded lightweight aggregate concrete encased steel (LWACES) columns after exposing to elevated temperatures. Sixteen concrete encased steel (CES) columns were considered in the study, 12 of which were exposed to elevated temperature then eccentrically loaded up to failure at different eccentricity ratios. The effect of temperature on the load–displacement relationships, failure load, and failure modes of the concrete encased steel (CES) columns was monitored and evaluated. Experimental results have shown that as the temperature increases, the load bearing capacity of the CES columns decreased. It has also been showed that, at high temperature, the normal‐weight concrete encased steel (NWCES) columns experienced larger degradation of the load bearing capacity compared to that of LWACES columns. Also, this study presents a numerical simulation of the behavior of LWACES columns at elevated temperatures with eccentric compressive load. The numerical model was implemented in conducting parametric study to understand the effect of temperature distribution, concrete cover, eccentricity ratio, and high temperature levels on the behavior of the thermally exposed (CES) columns. Numerical results have revealed that, at temperature value of 500°C, the ultimate capacity of LWACES with eccentricity ratios of 0.75, and 1 has decreased by 17%, and 23%, respectively, compared to that of the column with eccentricity ratio of 0.5.

Empowering lithium-ion storage: unveiling the superior performance of niobium-based oxide/perovskite heterojunction with built-in electric field

The increasing demand for high-performance electrode materials in lithium-ion batteries has driven significant attention towards Nb2O5 due to its high working voltage, large theoretical capacity, environmental friendliness, and cost-effectiveness. However, inherent drawbacks such as poor electrical conductivity and sluggish electrochemical reaction kinetics have hindered its lithium storage performance. In this study, we introduced KCa2Nb3O10 into Nb2O5 to form a heterojunction, creating a built-in electric field to enhance the migration and diffusion of Li+, effectively promoting electrochemical reaction kinetics. Under the regulation of the built-in electric field, the charge transfer resistance of the KCa2Nb3O10/Nb2O5 anode decreased by 3.4 times compared to pure Nb2O5, and the Li+ diffusion coefficient improved by two orders of magnitude. Specifically, the KCa2Nb3O10/Nb2O5 anode exhibited a high capacity of 276 mAh g−1 under 1 C, retaining a capacity of 128 mAh g−1 even at 100 C. After 3000 cycles at 25 C, the capacity degradation was only 0.012% per cycle. Through combined theoretical calculations and experimental validation, it was found that the built-in electric field induced by the heterojunction interface contributed to an asymmetric charge distribution, thereby improving the rates of charge and ion migration within the electrode, ultimately enhancing the electrochemical performance of the electrode material. This study provides an effective approach for the rational design of high-performance electrode materials.

Surface Atomic Rearrangement with High Cation Ordering for Ultra‐Stable Single‐Crystal Ni‐Rich Co‐Less Cathode Materials

AbstractIt is crucial to minimize cobalt content in Ni‐rich layered single‐crystal cathodes due to their high price and limited availability, yet it will inevitably lead to cation disordering, capacity degradation, and thermal issues. Herein, to overcome the intrinsic trade‐off between performance and composition of Ni‐rich Co‐less single‐crystal cathodes, a precursor engineering strategy with an epitaxially grown cobalt enrichment on the surface is innovatively proposed. In contrast to traditional coating modifications with random orientation and rigid surface‐bulk boundary, the epitaxially enriched surface cobalt layer on the precursor undergoes rapid interdiffusion with the internal Ni3+ during the optimized sintering process. This interdiffusion eliminates the surface‐bulk boundary, promoting the uniform distribution of cobalt and synergistically addressing the Li/Ni intermixing. Moreover, an enhanced surface Li+ diffusion is obtained, thereby suppressing the Li+ concentration gradient and intragranular cracks generation. Consequently, the modified LiNi0.7Co0.07Mn0.23O2 exhibits impressive cycling stability with increased capacity retention in both coin‐type half‐cells and pouch‐type full‐cells (91% after 1000 cycles), even under the harsh condition of high‐temperature, surpassing the majority of previously reported Ni‐rich cathodes. This work opens new avenues toward the low cost, high energy density, thermal stability, and long cyclic life for Ni‐rich Co‐less cathodes and sheds light on large‐scale commercial production.