Thermal Behavior Of Lithium-ion Batteries Research Articles

Experimental investigation of aging effects on thermal behavior of lithium-ion batteries during charging process

Thermal runaway generated by lithium-ion batteries is considered as one of the major hazards that exhibits great thermal risk during operation. The aging behavior, as an inevitable phenomenon after long-term cycling, largely contributes to the deterioration of thermal characteristics. In this paper, comparative experiments were conducted to investigate the aging cell thermal performance during the charging process. The results indicate that the aging cell with a high charging rate presents a higher thermal risk. With the decrease of SOH, the anode structure was destroyed and side reactions reduced the thermal stability. The thermal runaway onset temperature decreased from 274.8 ± 9.1 °C for fresh to 238 ± 1.2 °C for aging cells, and the corresponding critical time shortened by approximately 1 min. In addition, the maximum heat release rate increased by 37.5 %–45.5 % for aging cells under high charging conditions, manifesting that aging cells are more prone to trigger fire accidents. Finally, a modified risk assessment method was established. This study contributes to comprehending the coupling effects of aging behavior and charging rate thermal runaway mechanisms, and provides valuable guidance for thermal runaway detection during the whole life.

Analysis on the Thermal Behavior of Lithium-Ion Battery with Nickel-Rich Cathode and Silicon-Carbon Composite Anode

<div>Compared with traditional internal combustion engine vehicles, electric vehicles still have shortfall in driving range and energy replenishment time. In order to continuously improve the driving range of electric vehicles, the high-nickel/silicon-carbon lithium-ion battery with high energy density is a promising industrialized application route. However, with the increase of battery energy density, the heat generation of battery usually increases, which will inevitably bring greater heat dissipation problems to the battery thermal management system. To design a good thermal management system, the first thing is to accurately measure and deeply understand the heat generation characteristics of the battery. In this work, the heat generation behavior of a high-nickel LiNi<sub>0.8</sub>Co<sub>0.1</sub>Mn<sub>0.1</sub>O<sub>2</sub>/silicon-carbon pouch-type battery under different operating conditions were tested by an isothermal battery calorimeter. The influence of current rate, current direction, and operating temperature on the heat generation characteristics of the battery was systematically analyzed. A comparison between heat generation power of batteries with different cathode/anode materials was provided. The research results of this article can deepen the understanding of the heat generation behavior of LiNi<sub>0.8</sub>Co<sub>0.1</sub>Mn<sub>0.1</sub>O<sub>2</sub>/silicon-carbon battery and provide guideline for the design of thermal management system.</div>

Thermal Behavior Modeling of Lithium-Ion Batteries: A Comprehensive Review

To enhance our understanding of the thermal characteristics of lithium-ion batteries and gain valuable insights into the thermal impacts of battery thermal management systems (BTMSs), it is crucial to develop precise thermal models for lithium-ion batteries that enable numerical simulations. The primary objective of creating a battery thermal model is to define equations related to heat generation, energy conservation, and boundary conditions. However, a standalone thermal model often lacks the necessary accuracy to effectively anticipate thermal behavior. Consequently, the thermal model is commonly integrated with an electrochemical model or an equivalent circuit model. This article provides a comprehensive review of the thermal behavior and modeling of lithium-ion batteries. It highlights the critical role of temperature in affecting battery performance, safety, and lifespan. The study explores the challenges posed by temperature variations, both too low and too high, and their impact on the battery’s electrical and thermal balance. Various thermal analysis approaches, including experimental measurements and simulation-based modeling, are described to comprehend the thermal characteristics of lithium-ion batteries under different operating conditions. The accurate modeling of batteries involves explaining the electrochemical model and the thermal model as well as methods for coupling electrochemical, electrical, and thermal aspects, along with an equivalent circuit model. Additionally, this review comprehensively outlines the advancements made in understanding the thermal behavior of lithium-ion batteries. In summary, there is a strong desire for a battery model that is efficient, highly accurate, and accompanied by an effective thermal management system. Furthermore, it is crucial to prioritize the enhancement of current thermal models to improve the overall performance and safety of lithium-ion batteries.

Geometry-influenced cooling performance of lithium-ion battery

Battery geometry (shape and size) is one of the important parameters which governs the battery capacity and thermal behavior. In the dynamic conditions or during the operation, the performance of batteries become much more complex. Herein, the changes in thermal behavior of lithium-ion battery (LIB)by altering the geometry i.e., length to diameter ratio (l/d), is investigated. The geometries considered are named as large geometry (LG), datum geometry (DG) and small geometry (SG) with the l/d ratio of 5.25, 3.61, and 2.38, respectively. A three-dimensional (3D) multi-partition thermal model is adopted, and the numerical results are validated by the published experimental data. For three different cooling approaches such as radial, both-tab and mixed cooling, the average battery temperature and temperature heterogeneity are thoroughly examined considering the heat transfer coefficients (h) of 50 and 100 W/m2K at discharge rates of 1, 2 and 3C. Amongst, the minimum average battery temperature is exhibited by DG, the minimum radial temperature heterogeneity is obtained from LG, and substantial outperformance in terms of faster cooling rate is identified for SG, irrespective of the cooling approach employed.

Enhanced electrochemical and thermal behavior of lithium-ion batteries with ultrathick electrodes via oriented pores

The increasingly extensive application scale compels the development of lithium-ion batteries toward higher energy densities to eliminate endurance anxiety. Developing ultrathick electrodes to compress the proportion of inactive components is the most direct strategy to improve battery energy densities, although overshadowed by the enthusiasm of searching for new chemistry; however, sluggish ion transport kinetics, especially at high discharge rates, is the main challenge faced by thick electrodes. Here, we demonstrate two variants of oriented pore structures to enable ion fast transport in thick electrodes, and develop a quasi-3D electrochemical-thermal coupled model for lithium-ion batteries based on an open-source computational fluid dynamics platform to investigate their electrochemical and thermal behavior. The results show that the oriented pore electrodes yield an over 2-fold increase in the areal energy density of full-cells at the high discharge rate of 3C, and have a more uniform local distribution of Li ions in both electrolyte and electrodes. Meanwhile, the heat generation rate of battery can be reduced clearly due to their lower ohm resistance. Additionally, a comprehensive critical parameter analysis of oriented pores is performed with the aim of providing a further understanding for ultrathick electrodes that can help maximize the areal energy density of full-cells.

Thermal behavior of lithium-ion battery under variation of convective heat transfer coefficients, surrounding temperatures, and charging currents

In the transient state of the real-world environment, shedding light on the thermal behavior of Lithium-ion battery (LIB) has become crucial for strengthening the battery's safety. However, previous studies have not taken into account the concurrent dynamics of LIB parameters. This study employs an electrochemical thermal model to examine the thermal behavior of LIB when simultaneously varying the charging currents, surrounding temperatures, and heat transfer coefficients. The accuracy of the developed model is validated using experimental data of 18,650 LiCoO2/graphite LIB charged at 1C, 2C and 3C, as well as surrounding temperatures of 35, 50 and 60 °C, and convective heat transfer coefficients of 0, 4, 8, 12, 25, and 50 W/m2. K. The results show that the generated model and the experimental results agree well. The thermal behavior of the predicted model depicted three phases caused by battery warm-up, exothermic reaction and excessive build-up of heat from the two earlier stages. The simulation and experimental results had the highest relative error of less than 2.0% and the lowest root mean square error of 0.58 °C. As charging currents and surrounding temperatures rise concurrently, the battery surface temperature rises abruptly beyond safe limits. It is crucial to analyze how much convection would be necessary to maintain the battery's performance and overall health. Additionally, engineering/BMS/failure mitigation systems may benefit from understanding the curves' characteristics and the influence of convection, surrounding temperature and charging rates might, as by the time to peak temperature is reached the cell is already failed.

Quantification of heat energy leading to failure of 18650 lithium-ion battery abused by external heating

The presence of unavoidable extreme thermal fields, as well as frequent incidents of Lithium-ion battery (LIB) fires, emphasizes the importance of understanding the contribution of external heat energy to the degradation and failure of the LIB. In this study, we quantified the heat energy from the external heat source, heat transferred, and heat causing the safety vent crack to better understand the relationship between external thermal stress and LIB behavior during external heating tests. For experior data purposes, a series of external heating testing was performed with the NCA and LCO LIBs with 25–100% SOC. The external heat energy (qh) required to crack the safety vent varied between 92.70 and 232.80 kJ/m3 and 142.62–172.14 kJ/m3 for NCA and LCO, respectively. During venting at 25–100% SOC, the heat transferred for NCA and LCO were 56.77–136.07 kJ/m3 and 86.56–102.81 kJ/m3, respectively, representing 58.45–78.46% and 57.00–61.63% of the qh. Around 117.71–224.76 kJ/m3 and 181.10–218.59 kJ/m3 were produced by side reactions in NCA and LCO before the safety vent crack. The LIB's internal heat energy for breaking the safety disc (qsv) was estimated to be 174.49–360.83 kJ/m3 in NCA and 269.00–321.40 kJ/m3 in LCO. The qrec to qh ratio indicates that less qh may be required for the higher SOC LIB to enter stage II while the produced qgen reaches a maximum of 2 and 1.5 times that of qh for 100% NCA and LCO, respectively. During the breakout of the disc, the qsv exceeds the qh to about 2.4 and 1.9 times for 100% NCA and LCO, respectively. The findings of this study provide fundamentals on the thermal behavior of LIBs which can be used to understand the difference in hazard in transporting different types of LIBs, and decide how to implement designs for resisting thermal runaway propagation.

Computational modeling and statistical evaluation of thermal behavior of cylindrical lithium-ion battery

Understanding of thermal behavior of lithium-ion batteries under various operating conditions is crucial to develop robust battery thermal management system. Moreover, an accurate determination of parameter effects is essential for research, including battery thermal analysis and safety design. This article presents the battery temperature behavior of a 26,650 lithium-ion battery at multi-scale multi-dimension, combining computational modeling and statistical analysis. The thermal model was used to evaluate the complex effects of state-of-health, discharge current rate, heat transfer coefficient, and ambient temperature on the maximum battery temperature (Tmax) and the maximum battery temperature difference (dTmax). The current rate was the most significant parameter influencing both Tmax (delta = 0.85) and dTmax (delta = 14.95). The ambient temperature with the delta value of 0.51 was the second main factor affecting the Tmax, and the h with the delta value of 8.84 was the second crucial parameter for the dTmax. The effect of the SoH can be neglected compared to other discharge parameters. The statistical evaluation can potentially be used to assist battery thermal management systems. This study calls for more statistical methods to quantify battery temperature rise and correlate it with different charge/discharge parameters.

Investigation of Thermal Behavior of Cylindrical Lithium-Ion Batteries for Electric Vehicle

With growing concerns over climate change due to automotive emissions, fossil fuel depletion, and the increasing price of crude oil, electric vehicles have gained more interest as a mode of transportation. Various electric vehicles have been developed in recent years, including pure electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs). One of the keen focus area in the ongoing development of EVs is their energy storage systems. Mostly lithium-ion batteries are being used as an energy storage system in EVs. Various complicated reaction occurs during charging/discharging of batteries and the thermal behavior of the batteries are coupled to these reactions. Electrochemical reactions affect the heat generation rate, and higher temperatures further increase the speed of the electrochemical reactions. Adverse operating temperatures can impact battery performance, degradation, and safety. Hence it is become very important to investigate the thermal behavior of the lithium-ion batteries. Thermal investigation of cylindrical lithium-ion batteries of different chemistry and shape factor is conducted for different charging/discharging rate and atmospheric conditions using numerical technique. The numerical technique includes the determination of surface temperature of battery by solving the energy balance equation using suitable numerical method. The accuracy of numerical techniques is validated using the experimental techniques. Thermal investigation conducted in this research can help in deciding the operating strategies of battery management system and further in designing the proper thermal management system.

A temperature field superposition method for predicting the thermal behavior of lithium-ion battery

In order to improve the working performance of the lithium-ion battery in continuous charge-discharge process, in this study, the temperature field superposition method has been proposed to investigate the temperature response of the lithium-ion battery, which was based on the results of the thermal properties and the temperature dropping measurements, aiming to deeply analyze the thermal behavior of battery. The feasibility of the estimation of temperature field superposition method in temperature response of prismatic LiFePO4 battery has been verified firstly by comparing on surface temperature with experiments. Furthermore, the battery with composite phase-change materials (CPCM) has also been selected to demonstrate the practicability of temperature field superposition method. It could be induced that the differences between numerical and experimental results were consistency, which were both below 2 °C under the condition of 1 C, 3 C or 5 C discharging rate. Therefore, it can be concluded that the temperature field superposition method could not only evaluate the surface temperature response of the battery but also predict the thermal behavior accurately, rapidly and simply, which would effectively improve the thermal safety performance of battery.

Investigation of Thermal Behavior of Lithium-Ion Batteries under Different Loads

In this study, the thermal behavior and performance of pouch type Lithium-Ion Batteries (LIB) which are used in Hybrid Electric Vehicles (HEVs) and Electrical Vehicles (EVs) has been investigated at different discharge rates based on numerical simulations. Numerical simulation was performed through a traditional software package using the dual potential Multi-Scale Multi-Dimensional (MSMD) battery model to analyze the cell discharge behavior and investigate its thermal performance. When the battery load is increased, non-uniform thermal distribution and temperature rise has been observed. Non-uniform thermal distribution causes loss of capacity and performance in the battery. Therefore, an accurate and effective cooling system is required to eliminate non-uniform temperature distribution. This study is a preliminary preparation for cooling system design.

Modeling extreme deformations in lithium ion batteries

Abstract A simultaneously coupled modeling approach to study the electrochemical and thermal behavior of lithium-ion batteries under large mechanical deformation has been developed. The thermo-electrochemical pseudo-2D (P2D) battery model is coupled with a mechanical material model. Mechanical, thermal, and electrochemical models are implemented as user-defined sub-routines in the commercial multi-physics code LS-DYNA. The mechanical strain experienced by anode, cathode and separator results in thickness and porosity changes in each layer which in turn influences electrochemical behavior. The evolution of concentration profiles and cell potential are studied under different mechanical loading conditions. Internal short-circuits caused by mechanical deformation and corresponding physical behaviors are also elucidated. We discuss the competing effects of improved transport at higher temperature due to the internal short-circuit versus a drop in the effective ionic conductivity and electrolyte diffusivity due to mechanical deformation.

Effect of the active material type and battery geometry on the thermal behavior of lithium-ion batteries

The effect of different thermal conditions on battery performance has been evaluated by computer simulation through a thermal model coupled to the electrochemical model. Three different active materials, lithium cobalt oxide, LiCoO2, lithium iron phosphate, LiFePO4 and lithium manganese oxide, LiMn2O4, were evaluated together with two battery geometries: conventional and interdigitated. The delivered capacity of the different active materials and both geometries were thus obtained as a function of the scan rate and correlated with the produced reversible, reaction, ohmic and total heat. For isothermal conditions, the highest capacity is obtained for LiCoO2, being 739,31 Ahm−2 at 1C for the conventional geometry. Further, battery performance as a function of the scan rate is independent of the geometry and similar for the different active materials. Under adiabatic conditions and independent geometry, LiFePO4 produces lower heat in the discharge process, the temperature ranging from 298 K to 308.9 K when the battery operates up to 500C for and interdigitated geometry with eight digits, which is critical for improving battery safety. This fact is also confirmed by the ohmic heat value along the cathode at the rate of 300C, which is 42700 W m−3, 118000 W m−3 and 69000 W m−3 for LiFePO4, LiMn2O4 and LiCoO2, respectively, for a conventional geometry as at a time of 50s of battery operation. Thus, it is demonstrated how battery geometry and the intrinsic parameters of the active materials affect the heat generated by the batteries and, considering the balance between cycle performance and thermal properties, the best active material for improved battery safety and performance is LiFePO4.

Overcharge cycling effect on the thermal behavior, structure, and material of lithium-ion batteries

The present study investigates the overcharge cycling effect on thermal behavior, structure, and electrode material of lithium-ion batteries (LIB) with a Lix(Ni0.3Co0.3Mn0.2)O2 cathode. The thermal behavior of LIBs with different overcharged degrees was studied using vent sizing package 2 and differential scanning calorimetry. Changes in the internal composition of the batteries during overcharge were observed using a scanning electron microscope and an inductively coupled plasma optical emission spectrometer. The results indicate that the overcharge process can be divided into four stages. A battery was more likely to trigger thermal runaway during overcharge under adiabatic conditions than in an ambient environment. During overcharge, the surface temperature of a 150% state-of-charge (SOC) battery was approximately 3.0 °C higher than that of a 100% SOC battery. Because of generated gas and lithium deposition during overcharge cycling, the battery thickness increases and coulombic efficiency decreases. The apparent exothermic onset temperature (T0) of a battery with 150% SOC was 87 °C below that of a 100% SOC battery. Cathode material becomes highly reactive when the battery was overcharged to 150% SOC. Here, the released heat was 1026.4 J/g. These results provide feasible support for understanding the overcharge mechanism and battery management system.

Experimental study on thermal runaway risk of 18650 lithium ion battery under side-heating condition

To simulate the heat transfer process between lithium-ion batteries (LIBs), an electric heater with the same size and shape as LIB in this work is used to trigger thermal runaway event. The effect of state of charge (SOC), the power of heater, the cell spacing on thermal behavior of LIB was investigated as well the amount of transferred heat between the heater and LIB was calculated. The results indicate that 50% SOC is an unstable state for LIB, that a stronger jet flame becomes more likely when the SOC of LIB is higher than 50%. Additionally, the increased spacing, lower heating power and SOC can contribute to mitigate the severity of thermal runaway behavior. Further, the dominant path of heat transfer between the heater and LIB will also vary with operating conditions. The heat conduction through air is the main heat transfer path in tests with lower heating power. However, heat radiation will replace heat conduction as the primary heat transfer mode when there is a large temperature difference between the heater and LIB in tests with higher heating power. Understanding the leading heat transfer path between LIBs can provide valuable guidelines for the safety design of lithium-ion battery modules.

Thermal management of lithium-ion batteries: An experimental investigation

This paper describes a set of experimental tests carried out to better understand the thermal behavior of Lithium-ion batteries under load and the capability of various cooling fluids in maintaining the working conditions within a safe range for the cells. Despite several theoretical models are available in the literature, very few experimental data are reported.Different types of cells have been analyzed. The generation of hot spots has sometimes been registered, their occurrence being independent of cell geometry and size; instead, the battery's history and age, appeared the main factors in determining the onset of hot spots on the surface of the cell. Two experimental rigs have been set up to test the capability of different cooling fluids in removing the surplus heat generated in a Li-ion battery module, where the cells of interest have been replaced with electrically heated elements with the same thermal characteristics of the cells. It was thus possible to safely investigate “extreme” operating conditions, where the occurrence of a thermal runaway is possible. Among the tested fluids, air was unable to adequately limit the surface temperature increase, while a perfluorinated polyether, allowed to work within the optimal temperature range, even under severe operating conditions.

Experimental exploration of finned cooling structure for the thermal management of lithium batteries with different discharge rate and materials

Lithium-ion batteries in electric vehicles generate heat continuously, leading to high temperature of the battery packs and significant temperature differences between the battery cells, which eventually deteriorate the performance and lifespan of lithium-ion batteries. Therefore, a novel battery thermal management system that equipped the battery pack with fins was proposed and experimentally studied in this paper. The thermal behavior of lithium-ion batteries with different discharge rates and fin thicknesses was investigated. The results show that under natural-convection conditions, the addition of fins restricted the significant increase of the battery pack temperature and improved the uniformity of temperature distribution in the battery pack. Additionally, thicker fins satisfied the temperature requirements at higher discharge rates and greater discharge depths. Under condition of 2C discharge at 80% depth of discharge, compared to no clearance structure the 1 mm and 3 mm aluminum finned structure decreased the maximum temperature rise and the maximum temperature difference by 26.5%, 40.8%, and 9.5%, 33.3%, respectively. However, the trade-offs and optimization between the thermal load, weight, and volume increase caused by the addition of fins should be further investigated.

Influence of Low-Temperature Charge on the Mechanical Integrity Behavior of 18650 Lithium-Ion Battery Cells Subject to Lateral Compression

The study on the damage tolerance and failure mechanism of lithium-ion batteries (LIBs) subject to mechanical attack has attracted considerable attention. The electrochemical performance and thermal behavior of LIB were significantly affected by operation temperature and charging rate, but the dependence of these two factors on mechanical response remains unclear. Hence, we investigated how the environmental temperatures and rates in charging process affected the mechanical response characteristics of 18650 LIB cells. The onset of the short circuit in the cells which charged at temperatures above −25 °C occurred around their modulus peak under compression. At −25 °C, there was a strong possibility that a premature short circuit occurred locally in the cells during charging, thus they might show complex and variable mechanical response under compression. The failure moduli and crushing stresses of cells subject to compression tended to decrease as their ambient charging temperatures went down. Besides, 0.5 C-charged cells exhibited higher failure moduli and crushing stresses than the 1 C-charged cells above −20 °C. Morphology analyses of the cell electrode surfaces revealed that mossy lithium deposits became evident at temperatures below −10 °C. Furthermore, their distribution was uniform. Mechanical results also indicated that the short-term cycling at −20 °C and 0.5 C would soften the cell.

Electrochemical thermal modeling and experimental measurements of 18650 cylindrical lithium-ion battery during discharge cycle for an EV

Study of thermal performance in lithium-ion battery cell is crucial which directly affects the safety. Even though the operation of a lithium-ion battery cell is transient phenomena in most cases, most available thermal models for lithium-ion battery cell predicts only steady-state temperature fields. This paper presents a mathematical model to predict the transient temperature and voltage distributions of 18650 cylindrical lithium-ion battery at different discharge rates. For this, the 18650 cylindrical lithium-ion battery cell is tested inside the lab with an air-cooling method by four thermocouples mounted on the battery surface under four constant current discharge rates of 1 C, 2 C, 3 C, and 4 C in order to provide quantitative data regarding thermal behavior of lithium-ion batteries. Later, the numerical model is developed using ANSYS CFD software and it is found that the model predictions are in good agreement with experimental data for temperature and voltage profiles. The highest temperature is 46.86 °C at 4 C discharge rate as obtained from simulation. The results also show that the increased C-rates results in increased temperature on the principle surface of the battery.

Fast-charging investigation on high-power and high-energy density pouch cells with 3D-thermal model development

In this paper, insight of thermal behavior of lithium-ion batteries under fast-charging profiles is investigated. Although battery thermal behavior has been studied by published models, the reported modeling addresses a specific application: fast-charging applications. Most papers in literature present the fast-charging application from an electrical point-of-view. There, lacks a comprehensive electro-thermal model which can capture both the heat generation, voltage and current variation during the whole fast-charging process. In this study, two charging profiles that are commonly used for fast-charging applications are applied on two lithium-ion chemistries: lithium nickel manganese cobalt oxide (NMC) and lithium titanate (LTO). The first one is designed for high-energy density and the other made for high-power applications. To enlarge the study scope, the batteries have been tested at three environmental temperatures: 25°C, 10°C and 45°C. In addition, a three-dimensional thermal model has been developed within the frame of open source computational fluid dynamics (CFD) to analyze the thermal behavior of lithium-ion batteries (LiBs). Thermal evolutions of the cells during the profile are recorded to witness the temperature distribution and the validation of the model. The model has indeed well captured the evolution process of the cells from electrical and thermal point-of-views and achieved reasonably good agreement with the measurements. For example, LTO-based cells have shown an interesting behavior for which the battery was able to undergo a fast-charge at any tested temperature and the temperature still remained stable (a temperature rise of less than a 3°C). These parametric studies demonstrate that the model methodology can be used to predict LiB temperature distribution under fast-charging profiles.