Numerical investigation on thermal runaway propagation and prevention in cell-to-chassis lithium-ion battery system

Wang G., Ping P., Zhang Y., Zhao H., Lv H., Gao X., Gao W., Kong D.

Thermal runaway (TR) of lithium-ion batteries (LIBs) is always accompanied by the emission of combustible gases and the resulting jet fire may promote TR propagation in the battery module. An accurate TR propagation model incorporating jet fire provides insights into the cell-to-cell failure mechanism and aids the safety-optimal design of battery pack. In this work, a modeling framework based on conjugate heat transfer is developed to explore the interaction between jet fire and propagation behavior during TR. The LIBs are modelled by integrating chemical reactions, gas generation and jet dynamics, while the jet fire outside the cells is simulated by the CFD models involving combustion. The heat balance is employed to address TR propagation, which fully considers the energy flows between various elements of battery pack. The proposed model is capable of capturing the flame morphology and temperature evolution of cells, fire and ceiling plate, as confirmed by the TR propagation experiment under ceilings. Simulation results demonstrate that increasing the space confinement degrees shortens the propagation time interval by enhancing the convection from ejected gases and the radiation from flame. The reduction of ceiling height extends the flame extension length and significantly accelerates the cell-to-cell failure, highlighting the impacts of jet fire on TR propagation. This work presents a more realistic model for TR propagation, which can provide a pragmatic guidance for the battery pack's fire protection design and process safety assurance in the practical application.

Wang G., Kong D., Ping P., Wen J., He X., Zhao H., He X., Peng R., Zhang Y., Dai X.

Safety issues raised by thermal runaway (TR) are the main obstacle hindering the booming of lithium-ion batteries. A comprehensive model can potentially help improve understanding of the TR mechanisms and assist the battery pack design. However, previous models generally neglected the particle ejection, which is integral to predicting TR. In this study, a multi-scale model for the multiphase process of battery venting has been proposed, covering the entire chain of chemical reactions and physical transformation during TR. A lumped model in battery scale unveiled the interplay of thermal abuse progression and pressure accumulation. The computational fluid dynamics coupled with the discrete phase model was adopted to simulate both generated gases and ejected particles. The newly developed model was checked quantitatively by experimental measurements for battery temperature, jet velocity and mass evolution under thermal abuse. Simulation results highlight two violent ejections of particles and gases with inverted conical contours, consistent with visualization by laser technique in the experiment. The electrolyte vapours are found to dominate the gas release before TR, while the generated reaction gases become the major release after the burst of chain reactions. The developed model fulfils the TR prediction including particle ejection, which can provide new references for the thermal safety design of battery packs.

Wang G., Kong D., Ping P., He X., Lv H., Zhao H., Hong W.

Thermal runaway (TR) seriously hinders the wide application of lithium-ion batteries. One of the most significant hazards of TR lies in the emission of flammable gases, which might cause explosion in the battery pack. A TR model incorporating venting provides insights into reducing explosion risk and aids to determine the safety-optimal configuration of battery pack. In this study, a modeling framework is proposed to address gas venting and explosion hazard by coupling CFD and thermal resistance network. The TR propagation is predicted by a lumped network integrating heat generation and jet dynamics while the transport of gases is simulated by the CFD models. The developed model was confirmed by cell temperatures and gas concentrations measured by experiments and then adopted to examine the influence of various configurations of battery pack. Results demonstrate increasing ventilation rate can decrease the gas concentration and shorten the duration of battery pack under explosion whereas a limited effect of void volume is evident for that. Despite of reducing TR propagation speeds, the increase of cell distance can inhibit the rapid dispersion of venting gases, causing battery pack exposed to a prolonged explosion risk. The present model represents the further optimization of battery pack from the aspect of safety.

Zhang T., Qiu X., Li M., Yin Y., Jia L., Dai Z., Guo X., Wei T.

In recent years, frequent safety accidents resulting from thermal runaway propagation (TRP) bring concern on the further application of lithium-ion batteries (LIBs). TRP is a complex, interrelated and systematic process, the characteristics of which need to be investigated under dynamic variation of thermal insulation and heat dissipation conditions. Here, experiments and simulations are conducted to investigate the influence of dynamic heat conductivity (i.e. λ) and heat convection coefficient (i.e. h) on the TRP characteristics and prevention effectiveness, covering two core TRP suppression strategies: thermal insulation among adjacent batteries and heat exchange with the cooling system. It is revealed that the TRP mode can be divided into two types according to the variation of λ and h. In addition, through the heat flow analysis, it is found that the synergistic effect of thermal insulation and heat dissipation of battery module is the key to inhibit TRP. Therefore, we innovatively propose the three-dimensional credibility intervals: the functional relationship between λ and h that is required to completely block TRP or to make TRP time exceed 300 s, which provide a pragmatic guidance for different types of modules safety design in practical application.

Ghaeminezhad N., Wang Z., Ouyang Q.

Lithium-ion batteries are the preferred power source for electric vehicle applications due to their high energy density and long service life, thus significantly contributing to greenhouse gas emissions and pollution reduction. Their performance and lifetime are significantly affected by temperature. Hence, a battery thermal management system, which keeps the battery pack operating in an average temperature range, plays an imperative role in the battery systems’ performance and safety. Over the last decade, there have been numerous attempts to develop effective thermal management systems for commercial lithium-ion batteries. However, only a few analyze and compare thermal management techniques based on a control-oriented viewpoint for a battery pack. To fill this gap, a review of the most up-to-date battery thermal management methods applied to lithium-ion battery packs is presented in this paper. They are broadly classified as non-feedback-based and feedback-based methods. Finally, the paper concludes with a detailed discussion of the strengths and weaknesses of the reviewed techniques, along with some suggestions for future study. • A novel control-oriented classification of BTMS methods is proposed. • The various BTMS techniques are reviewed as non-feedback and feedback-based methods. • A benchmark is provided for researchers to interpret BTMS functions better. • Various non-feedback and feedback-based BTMS methods are compared. • The pros and cons of each method are discussed, and future direction is suggested.

Liu Y., Niu H., Liu J., Huang X.

Preventing thermal runaway propagation is crucial to ensure the safety of lithium-ion battery system, especially in low-pressure air-transport and the near-vacuum space environment. This work investigates the linear thermal-runaway propagation in LiNi 0.5 Co 0.2 Mn 0.3 O 2 18,650 cylindrical battery layers under ambient pressure from 0 atm to 1 atm. Results indicate that the 1-D layer-to-layer thermal runaway propagation rate decreases with decreasing SOC and ambient pressure. As the SOC decreases from 100 % to 30 %, the thermal runaway propagation rate decreases from 1.73 [layer/min] to 0.30 [layer/min] at 1 atm. For 30 % SOC cells, the thermal runaway propagation rate decreases by about 23 % as the ambient pressure decreases from 1 atm to 0.2 atm and eventually drops to zero at 0 atm. The X-ray computed tomography imaging reveals that low pressure can weaken both external flaming combustion and internal thermal runaway reactions during the venting stage. As the ambient pressure decreases, such dual effect increases the thermal runaway temperature from 200 to 310 °C, reduces the maximum surface temperature from 800 °C to 400 °C, and lowers the burning mass loss fraction from 32 % to 10 %. Finally, a simplified heat transfer model is proposed to explain the effects of SOC and ambient pressure on thermal runaway propagation. These findings provide a new way to mitigate the thermal runaway propagation and help to assess the safety of battery piles in storage and transport. • Explore linear layer-to-layer thermal-runaway propagation in LiNi 0.5 Co 0.2 Mn 0.3 O 2 18,650 battery. • Open-circuit cylindrical battery fire spreads under ambient pressure from 0.1 kPa to 100 kPa. • X-ray CT imaging reveals the pressure on external flame and internal thermal runaway reactions. • Find the influence of battery arrangement and initial heating intensity by review the literature data.

Wang B., Zhou Z., Li L., Peng Y., Cao J., Yang L., Cao B.

Lithium-ion batteries (LIBs) are one of the most promising technologies in electric vehicles and electric energy storage systems. However, safety accidents related to TR (thermal runaway) often occur. At present, large-format prismatic batteries have been put into use as part of the energy storage system. In practice, batteries often appear in the form of modules, which also increases the risk of TR control. The phenomenon of TR propagation of prismatic lithium-ion battery in modules is rarely studied. In this study, the TR behaviors of the single battery and module were investigated through overheating experiments. The results showed that the highest spontaneous-heating power of batteries with 0 %, 50 % and 100 % SOC (State of charge) are 67 W, 1336 W and 2308 W, respectively. Experiments also performed TR propagation experiments between monolayer and bilayer cell modules, which showed that TR is transmitted in the monolayer module, but not in different layer modules. In addition, compared with the single battery, the TR of the battery module in the propagation process is more intense, and the TR is most likely to fail in the propagation process of the second and the third battery. To gain a comprehensive understanding of the TR propagation of the prismatic LIB modules, a method to determine whether the TR will spread is achieved based on the spontaneous thermal power. This study further reveals the propagation behavior of heat abuse of prismatic lithium batteries, and its results provide guidance for the safety design and thermal hazard prevention of battery storage systems. • A model based on heat production is proposed to judge whether the battery will have thermal runaway. • The maximum spontaneous heat value of the battery under different SOC is revealed. • The TR propagation in high-capacity prismatic lithium-ion battery modules is revealed. • The difficulty of TR propagation between cells in the module has been compared. • The deficiency of the previous research on thermal runaway of high-capacity prismatic battery is supplemented.

Jin C., Sun Y., Yao J., Feng X., Lai X., Shen K., Wang H., Rui X., Xu C., Zheng Y., Lu L., Wang H., Ouyang M.

Innovative technology for electric vehicles has been developed in the past years, especially in the design of battery pack. Cell-to-pack (CTP) technology abandoned the conventional module structure and integrated the cell in the pack directly. The next generation Cell-to-chassis (CTC) technology will integrate the battery directly into the chassis fame. How to balance the integration considering both the safety and volume energy density is a challenging task. This paper uses the validated 3D model to investigate the conventional in-line configuration and new proposed brick configuration on thermal runaway propagation (TP) characterization. The in-line module occurs TP while the brick module doesn’t. The analysis of heat flux and heat energy flow among TR battery between adjacent normal batteries points out that the brick module has low peak heat flow and has more battery (heat capacity) to absorb heat, thus the brick can cease TP. In addition, the length of the brick module is optimized to improve the space utilization in CTC fame. Based on not adding thermal barriers, the volume energy density of brick configuration system decreases by less than 3% compare with in-line configuration system. This paper also proves that the structural design can improve the safety of battery system without adding cost. • Structural configuration can improve the safety of battery system is proposed and proved. • Brick module configuration for cell-to-chassis fame that can cease thermal runaway propagation is proposed. • Reducing the heat flux and heat energy between thermal runaway and normal batteries is the key for system safety design.

Takagishi Y., Tozuka Y., Yamanaka T., Yamaue T.

A comprehensive 3D heating test simulation model of a Li-ion cylindrical cell and module considering gas flow and combustion was developed. The model was based on the equivalent circuit model and included cell heating (Joule heating and thermal decomposition) gas ejection and flow from the cell, and gas combustion. First, the surface temperature and voltage profiles of a model of a commercial 18650-type cell were validated using an actual heating experiment. Subsequently, a simulated model of the battery module, comprising 98 cells heated by a burner was developed, and the thermal runaway behavior of the module was evaluated. The model facilitated the evaluation of the steps that occurred during heating the battery module until gas ejection, including melting of the housing, shutdown of the separator, and cell-to-cell propagation of the thermal decomposition reactions. Therefore, we believe that this can be a helpful tool for designing battery cells and modules. The models in this study were developed using COMSOL Multiphysics software.

Zhou Z., Zhou X., Wang B., Liew K.M., Yang L.

Thermal runaway (TR) propagation is a critical challenge in the safety application of lithium-ion batteries (LIBs). In this study, the battery modules with different connection modes are designed to reveal TR propagation mechanisms, and a passive strategy based on thermal insulation is proposed to inhibit TR propagation. The temperature, voltage, heat transfer of battery module, as well as the equivalent flux power during TR propagation are captured and analyzed. The batteries in parallel experience fiercer combustion and propagation in comparison with the batteries without connection, which is because the parallel connection mode intensifies the exothermic reactions inside the battery. Particularly, the energy from the former battery contributes to the dominant heat source for triggering TR of its adjacent battery, accounting for 52 %− 67 %. Compared to the module without connection, the module in parallel releases much higher heat flux to adjacent batteries, leading to shorter TR propagation time and severer TR propagation. Furthermore, the aerogel can completely prevent TR propagations with different connection modes. The average flux power of the former battery to its neighboring battery can be reduced from 400 W to 35 W by inserting aerogel. The results provide new insights into TR propagation mechanism and its prevention, which are beneficial to the safety design of battery modules. • Thermal runaway propagation and its prevention of batteries in parallel are studied. • The causes of fierce thermal runaway propagation in parallel batteries are revealed. • Thermal runaway propagation can be successfully prevented by thermal insulation. • The heat transfer and the equivalent flux power between batteries are quantified.

Zhai H., Chi M., Li J., Li D., Huang Z., Jia Z., Sun J., Wang Q.

Currently, the horizontal ceiling structure is widely adopted in large format battery systems. Thus systematically investigating the thermal runaway (TR) propagation behaviors features of large format lithium ion battery modules under different inclined ceilings is of importance for the safety design and protection of battery systems. This work focuses on the experimental phenomenon elucidation and theoretical analysis of the single cell TR and its propagation. Firstly, a single cell test is carried out to investigate the TR behavior features of target battery. Then, four sets of TR propagation tests with different ceiling angles (0°, 10°, 30°, 90°) are performed to explore the effect of inclined ceiling angle on TR propagation. Besides, a set of 0° ceiling angle experiment with fireproof barriers is conducted to study the blocking effect of barriers. Results show that a larger ceiling angle provides a better heat dissipation condition for modules, and the threshold value of ceiling angle at which TR stops propagating is between 10 and 30°. The barriers cannot block the TR propagation but great delay and weaken the propagation process. This study helps to enhance the insight of TR propagation behaviors and provides valuable guidance for the relative researchers and engineers. • Thermal runaway propagation behaviors under different ceiling angles are investigated. • The blocking effect of fireproof barriers on propagation is investigated. • The threshold value of ceiling angle at which the TR propagation stops is between 10 and 30°. • The heat transfer value in thermal runaway propagation process is calculated. • The significant deceleration effect of fireproof barriers on thermal runaway propagation is observed.

Hu J., Liu T., Tang Q., Wang X.

• Further insight to characterize TR of LIBs under charging is presented. • The heat transfer of each part between cells are analyzed in detail. • Acceleration of TR propagation under charging conditions in LIB cells is evidenced. Thermal runaway (TR) is the most critical safety issue of lithium ion battery (LIB), and more uncertain hazard factors may be introduced under working state. In this study, TR propagation in LIB modules during charging was investigated firstly. A shorter TR propagation time is observed with increasing charging rate, and the average TR propagation time at 3C charging rate is only 12.1% of that at 0.5C. Besides, the TR propagation exhibited an obvious acceleration effect and the TR onset temperature decreased with TR propagation at high charging rates, the lowest TR onset temperature is only 127.4 ℃. Redistributed current led to rapid heat generation of the remaining cells, and the side reaction heat gradually replaced the heat absorbed from surroundings and became the main source of heat accumulation. Coupled with the heat generation of charging, the TR propagation accelerated. In addition, the heat conduction through air accounts for 67% of the total heat transfer, so reducing the thermal conductivity between cells can be considered as a means of mitigating TR propagation. This study delivers an underlying analysis of TR propagation during charging, and which is expected to contribute references for the safety of LIB application.

Wang H., Xu H., Zhao Z., Wang Q., Jin C., Li Y., Sheng J., Li K., Du Z., Xu C., Feng X.

• A description of the characteristics of TR in Cell-to-Pack batteries is provided. • There is very low variability between jelly roll temperature at different locations. • The specific heat capacity and energy loss of the multiphase vents were calculated. • The time it takes for TR to propagate within the battery is affected by heating power. • The temperature of the jelly roll is 487℃ higher than the surface temperature. Thermal runaway and its propagation are the technological barriers for the large-scale promotion of new energy vehicles and energy storage. This paper investigates the temperature characteristics between jelly rolls, influence of heating power on internal propagation time and energy flow during thermal runaway propagation through experiments and models. Results indicated that the maximum temperature between jelly rolls has a maximum temperature difference up to 487℃ compared to the surface temperature during thermal runaway. The distribution of energy flow showed that approximately 60% of total energy was used to self-heated and approximately 31% was emitted through venting. Experimental results and model calculation shows that the time it takes for thermal runaway to propagate within the Cell-to-Pack battery is affected by heating power. This study provides a reference for creating safe cell designs, developing mitigation strategies for addressing thermal runaway propagation in system, and investigating battery-related accidents in new energy vehicles and energy storage.

Li K., Wang H., Xu C., Wu W., Zhang W., Hou J., Rui X., Chen Y., Fan L., Feng X., Ouyang M.

• An optimization method is employed to design side plates for a battery module. • Thermal safety and energy density of a battery module are effectively improved. • Average thermal runaway propagation time interval is prolonged by 46.0%. • Lightweight of a battery module with side plates fulfilled with a 59.6% mass decrease. • Effect of aggravating heat transfer through side plates is significantly weakened. Thermal runaway propagation in battery systems seriously hinders the rapid development of electric vehicles. Side plates are commonly employed to ensure the rigidity of the battery system, which can considerably affect the propagation behaviors. However, little attention has been focused on optimizing the design of side plates to mitigate the failure propagation from the perspective of weakening heat transfer. In this study, an orthogonal experimental design was applied to investigate the effects of the thickness, height and convective heat transfer coefficient of side plates, and the thickness of thermal insulating slices on regulating propagation behaviors. The results show that the height of the side plates is the most significant factor in the propagation process. Furthermore, a multi-objective optimization method based on a verified approximate model was proposed to design lightweight side plates with thermal safety. The Pareto frontier among the optimal objectives was obtained by using Non-dominated Sorting Genetic Algorithm II. The average propagation time interval is effectively prolonged by 46.0% after multi-objective optimization. Moreover, the mass of the side plates is decreased by 59.6%, resulting in a lightweight battery module. The local hot pot (battery failure point) first reaching the triggering temperature of the thermal runaway moves from both sides of the battery module to the center of the batteries. This study creatively presents the multi-objective optimization of side plates in a battery module to mitigate thermal runaway propagation. The results can provide valuable guidelines for the safety design of battery modules.

Kong D., Wang G., Ping P., Wen J.

Thermal runaway (TR) is a major safety concern for lithium-ion batteries. A TR model incorporating the resulting jet fire can aid the design optimization of battery modules. A numerical model has been developed by coupling conjugate heat transfer with computational fluid dynamics (CFD) to capture the cell temperature and internal pressure evolution under thermal abuse, venting and subsequent combustion of 18650 lithium-ion batteries. The lumped model was employed to predict the thermal abuse reactions and jet dynamics, while the vented gas flow and combustion were solved numerically. Model validation has been conducted with newly conducted experimental measurements for the transient flame height of jet fire and temperatures at selected monitoring points on the cell surface and above the cell. The validated model was then used to investigate the effect of the SOCs on the evolution of TR and subsequent jet fires. Increasing SOCs shortens the onset time of TR and enlarges the peak jet velocity. The peak heat release rates and flame height of the jet fire increase with the increase of SOC. The developed modeling approach extends the TR model to jet fire and it can potentially be applied to assist the design of battery modules. • A coupled conjugate heat transfer and computational fluid dynamics model. • Dynamic boundary conditions to couple internal and external parameters. • Capturing thermal runaway and jet fire behavior of lithium-ion battery.

Li H., Xu C., Wang Y., Zhang X., Zhang Y., Zhang M., Wang P., Shi H., Lu L., Feng X.

The thermal runaway propagation (TRP) model of energy storage batteries can provide solutions for the safety protection of energy storage systems. Traditional TRP models are solved using the finite element method, which can significantly consume computational resources and time due to the large number of elements and nodes involved. To ensure solution accuracy and improve computational efficiency, this paper transforms the heat transfer problem in finite element calculations into a state-space equation form based on the reduced-order theory of linear time-invariant (LTI) systems; a simplified method is proposed to solve the heat flow changes in the battery TRP process, which is simple, stable, and computationally efficient. This study focuses on a four-cell 100 Ah lithium iron phosphate battery module, and module experiments are conducted to analyze the TRP characteristics of the battery. A reduced-order model (ROM) of module TRP is established based on the Arnoldi method for Krylov subspace, and a comparison of simulation efficiency is conducted with the finite element model (FEM). Finally, energy flow calculations are performed based on experimental and simulation data to obtain the energy flow rule during TRP process. The results show that the ROM achieves good accuracy with critical feature errors within 10%. Compared to the FEM, the simulation duration is reduced by 40%. The model can greatly improve the calculation efficiency while predicting the three-dimensional temperature distribution of the battery. This work facilitates the efficient computation of TRP simulations for energy storage batteries and the design of safety protection for energy storage battery systems.

Murugan M., Elumalai P.V., Vijayakumar K., Babu M., Suresh Kumar K., Ganesh M., Kuang L., Prabhakar S.

ABSTRACTThe scientific aim of the study is to propose a comprehensive review of thermal management systems (TMSs) used in electric vehicle (EV) battery packs on matters pertaining to performance enhancement, improvements in safety, and reliability. This includes the various thermal management strategies, addressing some of the problems posed by the dynamic nature of operating conditions, and evaluating emerging TMS technologies. From this aspect, the problem of this research focused on the description of a detailed insight into the efficiencies of TMSs inside an EV, pointing to the impacts of various cooling mechanisms, mostly liquid cooling, air cooling, and phase‐change materials. The research study further evaluates the integration of TMS in vehicle design and its effects on battery lifespan, charging speeds, and environmental impacts. The benefits, disadvantages, and specific applications of each method are discussed about EVs. Taking into consideration the fast charging, high‐power, and environmental effects, further discussion is made on the specific challenges that come with dynamic operating conditions of EVs. This is shown through the industry's constant pursuit to develop in this critical area through the discovery of novel technologies, including predictive control algorithms and superior thermal materials. It discusses in depth how heat management is integrated into the general vehicle design and how this impacts battery lifespan, charging speed, and range. In conclusion, it is a source of material for research scholars, engineers, and policymakers in charge of developing EVs by synthesizing what already exists, highlighting trends at current times, and outlining possible future directions in the continuum of optimizing TMS for the next generation of driving automobile transportation batteries.

Yeganehdoust F., Madikere Raghunatha Reddy A.K., Zaghib K.

This paper reviews the growing demand for and importance of fast and ultra-fast charging in lithium-ion batteries (LIBs) for electric vehicles (EVs). Fast charging is critical to improving EV performance and is crucial in reducing range concerns to make EVs more attractive to consumers. We focused on the design aspects of fast- and ultra-fast-charging LIBs at different levels, from internal cell architecture, through cell design, to complete system integration within the vehicle chassis. This paper explores battery internal cell architecture, including how the design of electrodes, electrolytes, and other factors may impact battery performance. Then, we provide a detailed review of different cell format characteristics in cylindrical, prismatic, pouch, and blade shapes. Recent trends, technological advancements in tab design and placement, and shape factors are discussed with a focus on reducing ion transport resistance and enhancing energy density. In addition to cell-level modifications, pack and chassis design must be implemented across aspects such as safety, mechanical integrity, and thermal management. Considering the requirements and challenges of high-power charging systems, we examined how modules, packs, and the vehicle chassis should be adapted to provide fast and ultra-fast charging. In this way, we explored the potential of fast and ultra-fast charging by investigating the required modification of individual cells up to their integration into the EV system through pack and chassis design.

Yu J., Guo C., Yu J.

Rawat S., Saini D.K., Choudhury S., Yadav M.

Accurately predicting lithium-ion batteries’ state of temperature (SOT) is crucial for effective battery safety and health management. This study introduces a novel approach to SOT prediction based on voltage and temperature profiles during the abusive discharging process, aiming for enhanced prediction accuracy and evaluating the safety range. The duration of equal voltage discharge and temperature variation during discharge are considered temperature indicators. Linear regression and R2 analyses are employed to assess the relationship and variance over different discharge–charge cycles of varied duration between the complete life cycle and its temperature variance. In this study, a decision tree (DT) and an artificial neural network (ANN) are employed to estimate the SOT of a Li-ion battery. The effectiveness and accuracy of the proposed methods are validated using ageing data from eVTOL charge–discharge cycles through numerical simulations. The results demonstrate that for the short cruise range of 600 s, the DT algorithm with an R2 regression value of 6.17% demonstrates better performance than ANN, whereas for the bigger cruise range of 1000 s, the ANN model with an R2 regression value of 5.06 percent was better suited than DT. It is concluded that both DT and ANN outperform other methods in predicting the SOT of lithium-ion batteries.

Rawat S., Choudhury S., Saini D.K., Gupta Y.C.

Recognizing the challenges faced by power lithium-ion batteries (LIBs), the concept of integrated battery systems emerges as a promising avenue. This offers the potential for higher energy densities and assuaging concerns surrounding electric vehicle range anxiety. Moreover, mechanical design optimization, though previously overlooked, is gaining traction among researchers as a viable alternative to achieve enhanced energy and power densities. This review paper provides a comprehensive overview of recent research and progress in this domain, emphasizing the significance of battery architectures in enabling the widespread adoption of electric mobility. Beginning with an exploration of fundamental principles underlying LIB systems, the paper discusses various architectures involving different cell form factors, like pouch cells, cylindrical cells, and prismatic cells, along with their advantages and limitations. Furthermore, it reviews recent research trends, highlighting innovations aimed at enhancing battery performance, energy density, and safety through advanced battery system architecture. Through case studies and discussions on challenges and future directions, the paper underscores the critical role of advanced battery system architecture in driving the evolution of e-mobility and shaping the sustainable transportation landscape.

Zhou Z., Ding Y., Li C., Jia S., Wan J., Wu Y., Wang Q.

This work details a methodology that enables the characterization of thermal runaway behavior of lithium-ion batteries under different environmental conditions and the optimization of battery storage environment. Two types of widely-used lithium-ion batteries (NMC and LFP) were selected in this work. The coupled chemical and physical processes involved in the thermal runaway of lithium-ion batteries were simulated using a Multiphysics numerical solver. The developed model was verified against the data collected from the copper slug battery calorimetry (CSBC) experiment. Both the simulated and experimental results showed that the NMC battery with the state of charge (SOC) of 100% had the largest amount of heat generation compared to other cases. Additional simulations were conducted on this case to further quantify the combined effect of environmental factors (heating distance-d, ambient temperature-Tamb, and wind speed-v) on the thermal runaway behavior. The synergistic effect between v and d on mitigating thermal runway was found to be more significant than that between v and Tamb based on the calculated interaction coefficients. Furthermore, the settings of battery storage environment was optimized based on the defined space utilization rate α and cooling efficiency β. It was observed that at the same heating distance d, β reduced significantly with increasing wind speed. The scenario with d = 2 mm and v = 0.2 m s−1 had the highest total efficiency and thus was considered to be the optimal design. The findings of this work enable a safer design of battery thermal runaway mitigation/prevention system under different storage environmental situations.

García A., Monsalve-Serrano J., Dreif A., Guaraco-Figueira C.

The widespread use of e-bikes and e-scooters powered by lithium-ion batteries in urban settings has heightened safety concerns, particularly the risk of thermal runaway, which can result in dangerous incidents. The surge in battery-related fire incidents highlights the critical need for a deep understanding of thermal runaway phenomena. This study addresses this imperative by introducing a Multiphysics model combining pseudo-bidimensional electrochemical for simulating electrical performance, lumped thermal model for simulating the heat transfer behavior inside the module, and a thermal runaway kinetic model for propagation evaluation. This approach facilitates precise predictions of battery performance and proactively addresses safety concerns by incorporating thermal behavior simulations and predicting potential thermal runaway events. The model proposed allows the evaluation of different strategies for improving battery safety and performance, such as phase change materials and thermal insulators. Simulations reveal that implementing sodium hydrogen phosphate dodecahydrate (Na2HPO4··12H2O) as an intercell material substantially enhances thermal management. This material reduced the maximum temperature of the battery module by up to 30% during critical thermal runaway events. Additionally, it slowed the rate of temperature increase by 50%, significantly decreasing the possibility of adjacent cells reaching thermal runaway conditions. The research findings demonstrate the effectiveness of advanced thermal management strategies using PCMs to prevent potentially catastrophic thermal events in battery modules typical of micro-mobility devices.

Wang G., Ping P., Kong D., Peng R., He X., Zhang Y., Dai X., Wen J.

The broader application of lithium-ion batteries (LIBs) is constrained by safety concerns arising from thermal runaway (TR). Accurate prediction of TR is essential to comprehend its underlying mechanisms, expedite battery design, and enhance safety protocols, thereby significantly promoting the safer use of LIBs. The complex, nonlinear nature of LIB systems presents substantial challenges in TR modeling, stemming from the need to address multiscale simulations, multiphysics coupling, and computing efficiency issues. This paper provides an extensive review and outlook on TR modeling technologies, focusing on recent advances, current challenges, and potential future directions. We begin with an overview of the evolutionary processes and underlying mechanisms of TR from multiscale perspectives, laying the foundation for TR modeling. Following a comprehensive understanding of TR phenomena and mechanisms, we introduce a multiphysics coupling model framework to encapsulate these aspects. Within this framework, we detail four fundamental physics modeling approaches: thermal, electrical, mechanical, and fluid dynamic models, highlighting the primary challenges in developing and integrating these models. To address the intrinsic trade-off between computational accuracy and efficiency, we discuss several promising modeling strategies to accelerate TR simulations and explore the role of AI in advancing next-generation TR models. Last, we discuss challenges related to data availability, model scalability, and safety standards and regulations.

Nekahi A., Kumar M.R. A., Xia, Deng S., Zaghib K.

We conducted a comprehensive literature review of LiFePO4 (LFP) and LiMnxFe1-xPO4 (x=0.1–1) (LMFP)-based lithium-ion batteries (LIBs), focusing mostly on electric vehicles (EVs) as a primary application of LIBs. Although numerous individual research studies exist, a unified and coordinated review covering the subject from mine to chassis has not yet been presented. Accordingly, our review encompasses the entire LIB development process. I) Initial resources, including lithium, iron, manganese, and phosphorous; their global reserves; mining procedures; and the demand for LIB production. II) The main Fe- and Mn-containing precursors, Fe0, FexOy, FePO4, FeSO4, and MnSO4, focusing on their preparation methods, use in LIBs, and their effect on the electrochemical performance of the final active cathode materials. III) Use of the precursors in the synthesis of active cathode materials and pioneering synthesis methods for olivine production lines, particularly hydrothermal liquid-state synthesis, molten-state synthesis, and solid-state synthesis. IV) Electrode engineering and the design and optimization of electrolytes. V) Production of cells, modules, and packs. (VI) Highlights of the challenges associated with the widespread utilization of olivines in LIBs, emphasizing their safety, cost, energy efficiency, and carbon emissions. In conclusion, our review offers a comprehensive overview of the entire process involved in the fabrication of LFP/LMFP-based LIBs, from the initial elements in the mine to the assembly of the final packs that power EVs.

Peng R., Kong D., Ping P., Wang G., Gao X., Lv H., Zhao H., He X., Zhang Y., Dai X.

Large-scale application of lithium-ion batteries (LIBs) is limited by the safety concerns induced by thermal runaway (TR). In the field of TR research, numerical simulation, with its low risk and suitable cost, has become a key method to study the characteristics and mechanism of TR in LIBs. Early endeavors in TR modeling mainly concentrated on individual cells or a single scale, which may not completely predict the failure of cells in applications at the system scale, where various physical phenomena can take place simultaneously in a multitude of cells. This paper presents a comprehensive review of TR modeling technologies for LIBs from multi-scale perspectives. Firstly, the mechanism of LIBs' internal heat generation and the modeling process of the reaction kinetics are elucidated at the particle scale. Subsequently, TR triggering mechanisms of LIBs are expounded under various abuse conditions at the cell-scale, and the related models from single-physical to multi-physical fields are introduced. Evolution processes and underlying mechanisms of gas generation, venting, and combustion induced by TR are also analyzed, along with the latest modeling research. For the module scale, three technologies for the TR propagation are introduced, and the modeling studies are reviewed for the prediction of various behaviors affecting TR propagation. Then the discussion is conducted on TR modeling studies for gas diffusion, fire propagation, and gas explosion involved at the system scale. Finally, several strategies have been proposed to accelerate TR modeling technologies to embrace the trend of multi-scale models and multi-physics field coupled models.

Liu J., Wang L., Wang J., Pan R., Zhou X.

The characteristics of 16Ah nickel-cobalt-manganese (523) square soft-pack lithium-ion battery (16Ah NCM523) during typical thermal runaway (TR) process under abusive conditions including heat, overcharge, and mechanical stress were studied. The heat TR experiment of lithium battery with heating plate as heat source shows that the temperature of 16Ah NCM523 escalates from 19.9 ℃ to 62 ℃. The TR of 16Ah NCM523 occurs violently, and the temperature of the soft package burst is 96.4 ℃. And the voltage sag time during this TR of 16Ah NCM523 obviously laged behind the heat production characteristics of the battery. The results of overcharged TR of 16Ah NCM523 shows that the temperature of 16Ah NCM523 rises andante with a rate not higher than 1℃/s and then reaches 98.5 ℃. Following, the temperature of battery increases rapidly to 481.2 ℃. During overcharged TR of 16Ah NCM523, the voltage begins to drop rapidly 2 s earlier than temperature change, which means that voltage and temperature can be used as early warning signals of overcharged TR. For the nail penetration TR of 16Ah NCM523, at the moment of mechanical abuse, the battery bulges and erupts gas. At the same time, the voltage of 16Ah NCM523 drops to zero in a very short time (

Su W., Chen M., Wang Z., Zhong B., Nie Z.

This paper investigates the thermal battery as a research topic. We conducted an in−depth analysis of various thermal battery aspects, such as the cathode material CoS2 and electrolyte material morphology, crystal type, and interface state changes before and after service. The aim was to explore the core reaction and main failure mechanisms of the thermal battery. Prior to the reaction, the thermal battery cathode and electrolyte material consisted of pure−phase CoS2 and a composition of MgO−LiF/LiBr/LiCl. After service, the cathode and electrolyte of the single thermal battery exhibited significant morphological alterations caused by the presence of a molten state. The cathode transformed from CoS2 to Co3S4 and Co9S8 together with the presence of a marginal quantity of Co monomers visible throughout the discharge process, which was confirmed by means of XRD and XPS analyses. After the reaction, the electrolyte material was primarily made up of LiF, LiBr, and LiCl while the crystal components remained largely unaltered, albeit with apparent morphological variations. As was deduced from the thermodynamic analysis, the cathode material’s decomposition temperature stood at 655 °C, exceeding the working temperature of the thermal battery (500 °C) by a considerable margin, which is indicative of outstanding thermal durability within the thermal battery’s operational temperature range. Furthermore, the discharge reaction of the positive electrode was incomplete, resulting in reduced CoS2 residue in the thermal battery monomer after service. The reaction yielded a combination of Co3S4, Co9S8, and small amounts of Co monomers, indicating possible inconsistencies in the phase composition of the pole piece during the reaction process. In this study, we examine the distribution of residual stress in the thermal battery under various operating conditions. The simulation results indicate that exposure to a 70 °C environment for 2 h causes the maximum residual stress of the battery, which had an initial temperature of 25 °C, to reach 0.26 GPa. The thermal battery subjected to an initial temperature of 25 °C exhibited a maximum residual stress of 0.42 GPa subsequent to a 2−hour exposure to a temperature of −50 °C.

陈 蔚.

Cicconi P., Kumar P.

Nowadays, battery design must be considered a multi-disciplinary activity focused on product sustainability in terms of environmental impacts and cost. The paper reviews the design tools and methods in the context of Li-ion battery packs. The discussion focuses on different aspects, from thermal analysis to management and safety. The paper aims to investigate what has been achieved in the last twenty years to understand current and future trends when designing battery packs. The goal is to analyze the methods for defining the battery pack's layout and structure using tools for modeling, simulations, life cycle analysis, optimization, and machine learning. The target concerns electric and hybrid vehicles and energy storage systems in general. The paper makes an original classification of past works defining seven levels of design approaches for battery packs. The final discussion analyzes the correlation between the changes in the design methods and the increasing demand for battery packs. The outcome of this paper allows the reader to analyze the evolutions of the design methods and practices in battery packs and to understand future developments.