Large-scale Lithium-ion Batteries Research Articles

CO2e Life-Cycle Assessment: Twin Comparison of Battery–Electric and Diesel Heavy-Duty Tractor Units with Real-World Data

In 2023, the EU set the target to reduce greenhouse gas (GHG) emissions by 55% until 2030 compared to 1990. The European Transport Policy sees battery–electric vehicles as a key technology to decarbonize the transport sector, so governments support the adoption through dedicated funding programs. Battery–electric trucks hold great potential to decarbonize the transport sector, especially for high-impact, heavy-duty trucks. Theoretical life-cycle assessments (LCA) predict a lower CO2e emission impact from battery–electric trucks compared to conventional diesel trucks. Yet, one concern repeatedly mentioned by potential users is the doubt about the ecological advantage of battery–electric vehicles. This is rooted in the problem of a much higher CO2e impact of the lithium-ion batteries production process. As heavy-duty trucks have a much larger battery, the hypothec in the construction phase of the vehicle is significantly higher, which must be regained during the use phase. Although theoretical assessments exist, CO2e evaluations using real-world application data are almost nonexistent, as the technology is at the very start of the adoption curve. Exemplary is the fact that there were only 72 registered battery–electric heavy-duty tractor trucks throughout the whole of Germany at the start of 2023. This paper aims to deliver one of the first real-world quantifications using operational data for the actual reduction impact of battery–electric heavy-duty trucks compared to diesel trucks. This study uses the methodology of the life-cycle assessment approach according to ISO 14040/14044 to gain a systematic and holistic technology comparison. For this LCA, the system boundaries are considered from cradle to cradle. This includes the production of raw materials and energy, the manufacturing of the trucks, the use phase, and the recycling afterward. The research objects of this study are battery–electric and diesel Volvo FM trucks, which have been in use by the German freight company Nord-Spedition GmbH since May 2023. The GREET® database is used to assess the emission impact of the material production and manufacturing process. The Volvo tractor trucks resemble a critical case, as the vehicles have a battery size of 540 kWh—around 11 times larger than a usual passenger car. The operation data is directly provided by the logistics company to observe fuel/electricity consumption. Other factors are assessed through company interviews as well as a wide literature research. Finally, a large question mark concerning total emissions lies in the cradle-to-cradle capabilities of large-scale lithium-ion batteries and the electricity grid mix. Different scenarios are being considered to assess potential disposal or recycling paths as well as different electricity grid developments and their impact on the overall balance. The findings estimate the total emissions reduction potential to range between 34% and 69%, varying with assumptions on the electricity grid transition and recycling opportunities. This study displays one of the first successful early-stage integrations of battery–electric heavy-duty trucks into the daily operation of a freight company and can be used to showcase the ecological advantage of the technology.

Complex Battery Storage Fire Propagation Translational Forensic Study Using Cellular Automata

The surge in lithium-ion battery (LIB) use, essential for mass-scale renewable energy storage, raises concerns about fire hazards. However, to date, there is a lack of industry-wide understanding of large-scale LIB fire propagation. This paper suggests a translational forensic approach to promote fire safety awareness and introduces the cellular automata (CA) model coupled with the Monte Carlo (MC) approach to address the complex fire propagation simulation within an energy storage system (ESS). The objective is to demonstrate that the CA-MC model can provide a flexible and scalable connection for all levels of battery fire studies. The numerical model is coupled with experimental tests which have been performed to establish the actual timing of fire propagation from a single source. Cellular automata simulation, conducted through hybrid modeling and an applied risk analysis approach to evaluate fire hazards associated with LIBs, offers crucial insights into potential risks. The results demonstrate that, with fire incident initiation at a probability of 0.1 (10%), 33% of batteries will burn, and at a probability of 0.6 (60%) and beyond, the entire battery module will face complete burndown. Achieving full combustion of the entire module will take only approximately 42 timesteps on average, indicating rapid fire propagation. The actual time for a complete fire to occur in the battery module has been estimated to be 304 s per timestep, or 3.5 h total. Using this example, it is shown that the CA-MC approach can be extended to many other aspects of battery fire studies and is ideal as a translational tool, spanning all domains of the LIB industry.

Experimental investigation of thermal runaway behaviour and inhibition strategies in large-capacity lithium iron phosphate (LiFePO4) batteries for electric vehicles

Large-scale lithium-ion batteries play an important role in the electric vehicle market and the thermal runaway (TR) behaviour of batteries is one of the significant threats to the passengers. In this study, we conducted a series of thermal abuse tests concerning single battery and battery box to investigate the TR behaviour of a large-capacity (310 Ah) lithium iron phosphate (LiFePO4) battery and the TR inhibition effects of different extinguishing agents. The study shows that before the decomposition of the solid electrolyte interphase (SEI) film, temperature consistency within the battery were maintained and it was advisable to use temperature detectors. With the destruction of the internal structure of the battery and the uneven temperature distribution at the subsequent battery reaction stage, a large amount of combustible gas was released when the safety valve was opened. The combustible gas fire detector is used to improve alarm reliability and provided a stable early warning response time. Based on this TR behaviour, a LiFePO4 battery box with a standard size of 1060 × 660 × 250 mm was constructed. The TR inhibition effect of two different extinguishing agents (heptafluoropropane and perfluorohexanone) were investigated using a metal tube spraying method with a spraying dose of 1.8 kg (spraying rate of 0.06 kg/s) and a spraying pressure of 2.5 MPa. The results showed that using either of these, satisfy the requirements for TR inhibition in large-capacity LiFePO4 batteries and the flames could be completely extinguished without any reignition, and the chain reaction of the surrounding batteries was effectively prevented. Moreover, heptafluoropropane was proven to have a shorter fire-extinguishing time, whereas perfluorohexanone had the advantage of inhibiting temperature rise. This study provides valuable experimental results for early warning and inhibition of TR in large-capacity LiFePO4 batteries for electric vehicles.

Thermal runaway evolution of a 4S4P lithium-ion battery pack induced by both overcharging and unilateral preheating

To clarify the thermal runaway characteristics of lithium-ion battery pack, this study has established a thermal runaway experimental platform based on actual power battery pack. A 4 in series and 4 in parallel battery pack was assembled using 86 Ah lithium iron phosphate batteries, and the experiment of thermal runaway induced by overcharging and unilateral preheating was carried out. The behavior and characteristics including the temperature change characteristics of each cell, the heat generated and transfer paths during thermal runaway propagation, the voltage changes of each serial module and the total voltage, flame evolution behavior, gas generation characteristics, debris, and mass loss were investigated. The research results show that module 1 was the first to experience thermal runaway due to preheating. The redistributed current caused the batteries in the remaining modules to rapidly generate heat. Subsequently, the heat transfer from module 1 triggered thermal runaway in modules 2, 3, and 4 in sequence. The entire flame combustion process lasted for 38 min, with the maximum temperature reaching 937.1 °C, resulting in thermal runaway in all batteries. The sequence of thermal runaway has been clarified, with the flame generated by the ignition of the battery casing, connecting tabs, and combustible gases emitted from the batteries serving as the primary paths for heat transfer and thermal radiation. The experimental results provide valuable insights into the thermal engineering issues of large-scale lithium-ion battery pack.

Multi-Scale Risk-Informed Comprehensive Assessment Methodology for Lithium-Ion Battery Energy Storage System

Lithium-ion batteries (LIB) are prone to thermal runaway, which can potentially result in serious incidents. These challenges are more prominent in large-scale lithium-ion battery energy storage system (Li-BESS) infrastructures. The conventional risk assessment method has a limited perspective, resulting in inadequately comprehensive evaluation outcomes, which impedes the provision of dependable technical support for the scientific appraisal of intricate large-scale Li-BESS systems. This study presents a novel Li-BESS-oriented multi-scale risk-informed comprehensive assessment framework, realizing the seamless transmission of assessment information across various scales. The findings from a previous smaller-scale analysis serve as inputs for a larger scale. The evaluation process of this method is more scientifically rigorous and yields more comprehensive results compared to assessment technologies just relying on a single perspective. By utilizing the proposed comprehensive assessment methodology, this study utilized the emergency power supply of nuclear power plants (NPPs) as an application scenario, demonstrating the complete implementation process of the framework and conducting a comprehensive assessment of Li-BESS feasibility as an emergency power source for NPPs. Our findings propose a novel paradigm for the comprehensive assessment of Li-BESS, which is expected to serve as a scientific foundation for decision-making and technical guidance in practical applications.

Strategies and Perspectives on Enhancing Energy Density in Lithium-Ion Batteries

The rapidly growing demand for clean energy transportation and storage systems emphasizes the need for the development of large-scale lithium-ion batteries. Achieving this goal requires a comprehensive approach that considers not only technical aspects but also social, environmental, and economic perspectives. Specifically, the next-generation batteries should exhibit high energy and power densities, long-term cycle stability, and the efficient utilization of low-cost, abundant raw materials. The cathode material is the key determinant of these requirements. This presentation will introduce progress and strategies for enhancing cathode materials and their corresponding cell performances. These strategies include goals to enable reversible redox reaction processes through elemental and compositional choices, as well as crystal structural variations ranging from order to disorder. Furthermore, we combine these with advanced characterization techniques to understand the correlation between material properties and electrochemical behavior at multiple length and depth scales. The discussion also delves into a deeper understanding of the fundamental mechanisms of performance, coupled with advancements in new materials. Overall, the presentation aims to provide valuable insights into the strategy for developing the next generation of lithium-ion batteries.

Propagation dynamics of the thermal runaway front in large-scale lithium-ion batteries: Theoretical and experiment validation

Large-scale lithium-ion batteries are favored in electric vehicles and energy storage stations; for instance, BYD blade batteries and CATL Kirin batteries are popular. A tiny defect will trigger thermal runaway from a local point towards the other parts of the battery, and the boundary between the failure region and the intact region is called the “thermal runaway front,” of which the dynamics are still unclear. Herein, this paper deduces two formulas for the moving speed (vTR) of the thermal runaway front by applying the principles of energy conservation (Formula I) and flame front (Formula II); formulas for the thermal runaway front velocity (vTR) are derived. The velocity vTR conforms to the 1/2 power of the heat conductivity and reaction rate in both formulas. Data regression for the experimental data demonstrated that the overall estimation error was 10 % using Formula I and 25 % using Formula II. As the zero velocity value indicates the termination of thermal runaway propagation, further derivations reveal that forced cooling can suppress thermal runaway as long as the heat dissipation power is higher than the heat generation power. Sufficient heat dissipation time is achieved by the time delay of heat transfer in the long run of thermal runaway propagation. The formula for the dynamics of thermal runaway propagation universally applies to various large-scale lithium-ion batteries, assisting the safe design of high-energy batteries and providing new insights into suppressing battery thermal runaway by the heat transfer delay effect.

Investigating the Structure and Performance of Electrodes Made by Dry and Wet Slurry Processes

Performance, cost, and safety are vital factors in producing and handling lithium-ion batteries. Using a dry process reduces the cost and environmental impact of producing large-scale lithium-ion battery electrodes significantly as solvents are eliminated. Thus, in this study, solvent-free dry electrostatic spray deposition (ESD) and conventional slurry processes were compared to uncover the influence of the manufacturing process on thick LiNi0.8Mn0.1Co0.1O2 (NMC 811) positive electrodes. More pressure during calendering was found necessary for the dry-made (dry) electrodes to have the same porosity, leading to more cracks within the NMC particles and better adhesion. At slower discharge rates, below 2 C, the dry electrodes exhibited a higher specific capacity or about the same capability than that of the slurry-made ones. At higher discharge rates, greater than 2 C, both types of electrodes have poor rate performance, though the slurry-made (slurry) electrodes had a slightly higher capacity. Despite more calendering-induced cracks in the dry electrodes, both electrodes had comparable long-term cycling behavior when tested in full cells with graphite-negative electrodes. This study shows the viability of using the dry-powder ESD process for manufacturing thick electrodes with high active material content, meeting the need for high energy demand.

Thermal behaviour of large scale lithium-ion battery for electric vehicle and hybrid electric vehicle application: a review

Thermal behaviour of large scale lithium-ion battery for electric vehicle and hybrid electric vehicle application: a review

Thermal behaviours of large scale lithium-ion battery for electric vehicle and hybrid electric vehicle application: a review

Thermal behaviours of large scale lithium-ion battery for electric vehicle and hybrid electric vehicle application: a review

A Physics-Informed Composite Network for Modeling of Electrochemical Process of Large-Scale Lithium-Ion Batteries

A Physics-Informed Composite Network for Modeling of Electrochemical Process of Large-Scale Lithium-Ion Batteries

Open access dataset, code library and benchmarking deep learning approaches for state-of-health estimation of lithium-ion batteries

Great progress has been made in deep learning (DL) based state-of-health (SOH) estimation of lithium-ion batteries, which helps to provide recommendations for predictive maintenance and replacement of lithium-ion batteries. However, despite the abundance of articles, few open-source codes are publicly available. While there are several public datasets, they tend to be more oriented toward simulating laboratory environments rather than real-world usage scenarios. Moreover, they solely provide raw data without any corresponding preprocessing codes, resulting in inconsistencies in preprocessing methods across different papers. These reasons lead to unfair comparisons and ineffective improvements. In response to these problems, this paper publishes a large-scale lithium-ion battery run-to-failure dataset, consisting of 55 batteries, and provides a unified data preprocessing method. Besides, we comprehensively evaluate 5 well-known DL-based models to provide benchmark research. To be specific, first, the existing DL-based SOH estimation methods are reviewed in detail. Second, we provide a comprehensive evaluation of DL-based models on 2 large-scale datasets, including 100 batteries, with 3 input types and 3 normalization methods. Third, we make the complete evaluation codes and dataset publicly available for better comparison and model improvement. Fourth, we discuss future DL-based SOH estimation, including unsupervised learning, transfer learning, interpretability, and physics-informed machine learning. We emphasize the importance of open-source code, provide baseline estimation errors (error upper bounds), and discuss existing issues in this field. The code library is available at: https://github.com/wang-fujin/SOHbenchmark.

Understanding the influence of the confined cabinet on thermal runaway of large format batteries with different chemistries: A comparison and safety assessment study

With the increasing development of large format lithium-ion batteries (LIBs) in automotive sectors, thermal runaway (TR) and fire hazards have become crucial challenges. A series of overheating experiments were performed on four large format LIBs with various chemistries under two conditions. To simulate the electric vehicle applications, the cabinet was employed in the confined space tests. The results showed that under the condition of stopping heating at safety venting (SV), all LiNixCoyMnzO2 (NCM) cells caught fire and TR, while no TR occurred for LiFePO4 (LFP) cells. The LFP cells cannot ignite spontaneously but only spray the electrolyte during TR. The triggering temperatures of TR for NCM cells are similar and close to the temperature of SV for LFP cells. For NCM LIBs, with the ratio of nickel increasing, the TR hazards increase, including the thermal and toxic hazards, larger than that of LFP cells. From the aspects of the TR risks and TR hazards, a safety assessment method was established to grade the fire hazards. Compared with open space tests, the LIBs with different chemistries in confined space tests have the same TR risks but lower TR hazards. The fire-induced toxicity was quantitatively evaluated by determining the fractional effective concentration and fractional effective dose. Moreover, the fire of LIBs is compared to the gas jet flame and pool fire of several typical fuels. Such a comparison analysis on large-scale LIBs with different chemistries can contribute to the selection of cells and safety design for automotive sectors.

Introduction to grid‐scale battery energy storage system concepts and fire hazards

AbstractAs the world continues to enact progressive climate change targets, renewable energy solutions are needed to achieve these goals. One such solution is large‐scale lithium‐ion battery (LIB) energy storage systems which are at the forefront in ensuring that solar‐ and wind‐generated power is delivered when the grids need it most. However, the perceived hazards of LIBs due to recent events in the United States and Australia pose a risk to their future success. When a battery energy storage system (BESS) has a multilayered approach to safety, the thermal runaway, fire, and explosion hazards can be mitigated. Successful implementation of this approach requires cooperation, collaboration, and education across all stakeholder groups to break down these preconceived notions. Much can be learned from the recent BESS fire and explosion events to inform safer design and operation. These events and their contributing factors share many commonalities with historic losses in the hydrocarbon industry. Fire and process safety engineers who have traditionally worked in the hydrocarbon industry can be of immense value to the BESS industry.

Thermally Conductive Nitride-Based Ceramic-Coated-Separator for Lithium-Ion Batteries

As the demand for electric vehicles (EVs) increases, a lot of research to achieve high-energy-density lithium-ion batteries (LIBs) is being actively conducted. However, charging an EV, which takes longer than refueling an internal combustion engine vehicle (ICEVs), is still a common concern. As a way to address this problem, high-rate charging can lead to heat accumulation inside LIBs. In particular, in the case of polyolefin-based separators such as polyethylene and polypropylene, which are currently widely used in LIBs, their low melting temperature threatens the safety of cells during fast charging. To compensate for the low thermal stability of these polyolefin-based separators, ceramic-coated separators (CCS), in which a ceramic coating layer is introduced on the surface of the separator, have now become an essential component for securing the safety of LIBs. Nevertheless, conventional oxide- or hydroxide-based ceramic materials such as Al2O3, Mg(OH)2, AlOOH, etc. still have low thermal conductivity to suppress the heat accumulation especially in large-scale LIBs. Thus, CCSs were fabricated using a nitride-based ceramic material having excellent thermal conductivity. After the CCS was prepared, air permeability, ionic conductivity, thermal stability, and adhesion properties of the ceramic coating layer were measured to be compared with those of Al2O3-based CCSs. In addition, the thermal conductivity of nitride- and oxide-based CCSs are compared to confirm the possibility to improve the heat dissipation characteristics of the LIBs.

Voltage Differential Analysis during Power Discharge Operation in Energy Storage Systems

Constant Power Discharge (CPD) is a lucrative operating mode for grid-tied ESS in many energy markets. The CPD mode corresponds to an increasing current drawn as the ESS discharges. The operation can be modeled with an aged anode and cathode open circuit potentials (OCPn/p+RRC) model that can let us identify electrode-level (eSOH) parameters and resistance growth even though we do not have slow discharge with Constant Current. This identification process from realistic ESS field data, namely constant power discharge, will enable continuous eSOH diagnostics and lead to real-time and operando quantification of loss of active material and loss of lithium inventory (LAM and LLI, respectively).In addition, the timing of when the cell groups' differential voltage peaks occur when the battery system is under constant power operations inform us about the imbalance among cell groups in a module of a battery system, as shown in the figure. Using the time separation among cell differential voltage peaks as a metric of cell imbalance can improve cell balancing algorithms that measure cell imbalance using maximum or minimum voltage, which can be directly affected by the power limits of the battery system.The efficacy of the proposed algorithms is evaluated for multi-cell modules consisting of NMC/graphite cells, operating as part of a large-scale grid-connected energy storage system. Ultimately, by enabling improved diagnostics of the state of health of individual cells in a battery system and improved cell balancing algorithms, this work will enhance the performance and safety of large-scale lithium-ion battery systems. Figure 1

Experimental Investigation of Thermal Runaway Behavior and Hazards of a 1440 Ah LiFePO4 Battery Pack

The thermal runaway (TR) behavior and combustion hazards of lithium-ion battery (LIB) packs directly determine the implementation of firefighting and flame-retardants in energy storage systems. This work studied the TR propagation process and dangers of large-scale LIB packs by experimental methods. The LIB pack consisted of twenty-four 60 Ah (192 Wh) LIBs with LiFePO4 (LFP) as the cathode material. Flame performance, temperature, smoke production, heat release rate (HRR), and mass loss were analyzed during the experiment. The results indicated that TR propagation of the LIB pack developed from the outside to the inside and from the middle to both sides. The development process could be divided into five stages corresponding to the combustion HRR peaks. In the initial stages, the main factor causing LFP battery TR under heating conditions was the external heat source. With the propagation of TR, heat conduction between batteries became the main factor. Hazard analysis found that the HRRmax of the LIB pack was 314 KW, more than eight times that of a single 60 Ah battery under heating conditions. The LIB pack had higher normalized mass loss and normalized THR (6.94 g/Ah and 187 KJ/Ah, respectively) than a single LFP battery. This study provides a reference for developing strategies to address TR propagation or firefighting in energy storage systems.

A multi‐objective parallel layered equalizer for large‐scale lithium ion battery system

The equalisers available are difficult to give consideration to both high balance efficiency and fast balance speed, and their performances are unstable as the number of the series-connected batteries increases, so they are unsuitable for a large-scale battery system. A multi-objective parallel layered equaliser based on battery working states for the large-scale lithium-ion battery system is presented. The equaliser has two types of balance objects and two corresponding layers, and the first layer and the second layer take the single battery and the battery unit as the balance object, respectively. The multi-objective parallel layered balance means that multiple balance objects are selected as the balance objectives simultaneously at each layer. The balance speed is fast due to the multi-objective parallel balance. The balance efficiency is high due to the short energy path and the complementary pulse width modulation (PWM) control in the first layer, and the double voltage value of the balance object in the second layer. Moreover, the performance of the equaliser is stable, even when the number of series-connected batteries is large. In short, the proposed equaliser features high efficiency, fast speed, and strong scalability. Further, the experimental platform for a battery system with twelve series-connected lithium-ion phosphate batteries is built, and then the balance experiments have been completed. Finally, the effectiveness of the equaliser is verified by the corresponding experimental results.

Study of Improving the Thermal Stability of Ceramic Coated Separator Via Chemical Crosslinking between Ceramic Particles and Polymeric Binders

Lithium-ion batteries (LIBs) are used in everyday applications such as portable electronics and electric vehicles (EVs) in our daily life. In large-scale batteries such as EVs, high energy density has been developed to secure longer mileage with one charge. Securing battery safety becomes extremely challenging as densifying the cell energy and increasing the battery. The safety of batteries must be guaranteed from the cell to the module, the pack, and the system, and it must not be ignored at every step. The separator is highlighted at the cell level as it plays an essential part in safety. To guarantee the safety of large-scale LIBs, it is essential to employ a ceramic-coated separator (CCS). To secure thermal stability using CCSs, the certain thickness of ceramic coating layer (CCL) is required. In contrast, the thicker CCL can act as a resistive layer in the cell, and in the worst case, the ceramic that has fallen off the CCS surface can act as a side reactant in the cell. However, if the CCL is thin, the desired thermal stability may not be obtained. The key technology is to improve adhesion while reducing the thickness of the CCL.For this purpose, polydopamine nano layer is preliminary introduced on the surface of ceramic particles via simple solution polymerization. Then, poly(acrylic acid) binder, which can react with amine groups in polydopamine, is chosen for aqueous ceramic coating slurry. Thus, this combination can make several crosslinking points within CCL, which lead to higher adhesion within the CCL after electrolyte impregnation. As a result, the adhesion within the CCL of cross-linked CCS is increased by 70% compared to the non-crosslinked CCS. Furthermore, the adhesion does not decrease when impregnated with the electrolyte. Also, cross-linked CCS showed better shrinkage property than commercialized CCS with the same composition because the cross-linked CCS did not shrink even when exposed for 1 hour at a high temperature of 160 °C. From this study, with crosslinking reaction within coating layer, it is possible to improving heat resistance and physical properties of separator without increasing thickness of CCL.

State of health monitoring by gas generation patterns in commercial 18,650 lithium-ion batteries

• Non-disruptive lab made Raman spectroscopic system is applied for gas analysis. • Four distinct phases of gas expulsion were found until commercial LIB’s end of life (EOL). • Mathematical model related to SOH is proposed based on the 4 gas expulsion phases. Because large-scale lithium-ion battery (LIB) packs are compactly constructed using many LIB cells, one battery can cause fire of the other LIB cells when a few cells of them are damaged by accident owing to the latent risk of thermal decomposition reactions. To alleviate this problem, research seeks to provide an understanding of the gas generating mechanisms during cycling, electrolyte decomposition, and electrode material reactions. Understanding gas behaviors can prevent propagation of a battery fire and other hazardous situations. Therefore, in this study, we investigate commercial 18,650 cylindrical cells with long-term cycling. A lab-made in-situ Raman spectroscopic system and comprehensive transient electrochemical analyses are utilized to explore four gas expulsion phases. In addition, gas generation data are assessed for various overcharging voltage cutoffs (4.2–4.6 V). For the first time, furthermore, a simple empircal mathematical model is proposed, based on the distinct gas evolution phases, that can provide the insight into the state of health (SOH) of commercial 18,650 cells.