Numerical Investigation of Passive Thermal Management of Batteries in Electric Vehicle Using Nano Enhanced Phase Change Materials

Critical insights and recent updates on passive battery thermal management system integrated with nano-enhanced phase change materials

The effective thermal management of Lithium-Ion Batteries (LIBs) is essential for ensuring safety, extending cycle life, and maintaining performance in electric vehicle applications. Among various approaches, passive battery thermal management systems (PBTMS) using phase change materials (PCMs) provide a cost-effective and reliable solution compared to conventional active cooling. This study proposes a novel conical cylindrical chamber (CCC) design for PCM encapsulation and evaluates its impact on LIB temperature regulation. A three-dimensional Computational fluid dynamics (CFD) model based on the enthalpy–porosity method was developed to simulate coupled heat transfer and phase change phenomena under dynamic discharge conditions. The effects of chamber geometry (top and bottom radii), different PCM types, and discharge rates (1–3 C) were systematically investigated. Results show that chamber configuration strongly influences PCM melting efficiency and battery thermal response. For example, the optimized CCC geometry reduced peak battery temperature by nearly 30 °C compared to less efficient designs, while poorly configured chambers left up to 38% of the PCM unmelted at end of discharge. The study demonstrates that balancing CCC surface area and PCM volume is critical for maximizing heat absorption, minimizing thermal gradients, and enhancing passive cooling. These findings provide design guidelines for next-generation passive thermal management systems in LIB applications.

This study examines the efficacy of phase change material (PCM) and nano-enhanced phase change material (NePCM) in regulating the thermal dynamics of lithium-ion batteries (LiBs) during rapid discharges. Lithium-ion batteries produce significant heat at high discharge rates, potentially resulting in performance decline and safety hazards, such as thermal runaway. To resolve this issue, layers of PCM (RT44HC) and NePCM were implemented around the battery cell, and their thermal performance was assessed at discharge rates of 1C, 2C, and 3C. Temperature profiles were examined under three conditions: bare cell (lacking thermal management), PCM, and NePCM. The findings indicate that both PCM and NePCM effectively mitigate temperature increases, with NePCM consistently exhibiting enhanced performance. At 1 °C, NePCM diminished the temperature increase by 33.3%, whereas at 3 °C, it attained a 21.3% reduction relative to the uncoated cell. The improved performance is due to the augmented thermal conductivity offered by nanoparticles in NePCM, enabling expedited and more uniform heat dissipation. NePCM demonstrated significant advantages at elevated discharge rates, where thermal management requirements are paramount. NePCM presents a viable solution for enhancing battery safety and operational stability, rendering it appropriate for use in electric vehicles and high-energy storage systems.

Role of nano-additives in the thermal management of lithium-ion batteries: A review

Advanced 3D-printed phase change materials

Battery thermal management systems (BTMS) are an important component of electric vehicles. BTMS provide key safety measures with the aim of maintaining operating temperatures of Li-ion cells within optimum ranges between 15 – 35 °C and a maximum 5 °C difference across the cell.1 Current commercial BTMS use air or liquid cooling to maintain optimum temperatures of Li-ion cells, which can be bulky, reducing volumetric and gravimetric energy densities of the battery pack. Additionally, the most effective systems, active BTMS, require energy from the battery to pump the cooling fluid resulting in less energy being available from the battery pack for useful work. Without BTMS in place, cells can exceed 60 °C leading to cycle life loss or thermal runaway.2 To overcome these issues, in recent years there has been great interest in including phase change materials (PCMs) in BTMS. PCMs make use of latent heat and can store and release up to 150 - 250 J•g-1 of energy to passivelymanage cell temperatures. It has been demonstrated that PCMs can keep cells below 50 °C when cells are subject to fast charging conditions in addition to being more energy efficient than active BTMS requiring no additional energy input from the cell.3 However, effective integration of PCMs into BTMS has proven difficult due to the low thermal conductivity and tendency for leaking of the active PCM.3 Current methodologies for integration have involved the development of composite PCMs – a porous housing for the PCM. The composite PCM allows additives such as graphene to enhance thermal conductivity and leakage prevention.4 However, concerns remain about PCM integration into battery packs and volumetric efficiency as a remaining barrier for full commercialisation.Micro-encapsulation, i.e., the formation of a thin, non-permeable shell around a PCM core, provides an increased surface area-to-volume ratio resulting in a smaller volume requirement for heat absorption.5 The micro-encapsulation of PCMs can also be used to mitigate leakage during operation and has previously been suggested to enable the use of PCMs in thermal management systems but there have been limited attempts demonstrating a practical use.6 In this work, Octadecane (C18H38, melting point 27 °C) has been encapsulated using a graphene oxide (GrO) shell, producing capsules with a diameter of 2 µm. The PCM/GrO capsules were applied to LiFePO4|Graphite 18650 cylindrical cells (RS Pro, 1600 mAh), via an outer coating (~3 mm thick), to passively manage the thermal performance of the cell. The coating had a latent heat of melting of ~100 J g-1 and thermal imaging was used to assess temperature change of the cycling cells.Cells were tested under fast charging conditions to assess the efficacy of the coatings (Figure 1). At a rate of 2C (3.2 A), the ~3 mm thick PCM/GrO coating was able to reduce the peak cell temperature by 8 °C during charging compared with an uncoated cell, requiring only a 13% increase in total mass of the cell.The PCM/GrO capsule coatings have the advantage of direct application to the exterior of the cell without the additional need of external components or cell stacking. The coating makes good contact and allows cells to be independent of each other allowing for straightforward implementation into an existing BTMS. Furthermore, coating formulations can be readily modified to select desired temperature maxima. Figure 1 Temperature profile of a coated and uncoated cell cycling by initially resting for 30 minutes and then discharging at 0.5 C (C = 1600 mAh) to 2.6 V. Cells were then charged at 2 C to 4.5 V followed by an hours rest. Thermal images were taken every 20 seconds. D. Chen, J. Jiang, G.-H. Kim, C. Yang, and A. Pesaran, Appl. Therm. Eng., 94, 846–854 (2016).J. Luo, D. Zou, Y. Wang, S. Wang, and L. Huang, Chem. Eng. J.l, 430, 132741 (2022).R. Kumar and V. Goel, J. Energy Storage, 71, 108025 (2023).Z. Li, Y. Zhang, X. Wang, F. Cao, X. Guo, S. Zhang, and B. Tang J. Power Sources, 603, 234447 (2024).E. Shchukina, M. Graham, Z. Zheng, and D. Shchukin, Chem. Soc. Rev., 47, 4156–4175 (2018).J. Gu, J. Du, Y. Li, J. Li, L. Chen, Y. Chai, and Y. Li, Energies, 16, 1498 (2023). Figure 1

Electric vehicle (EV) demand has increased, therefore the use of lithium batteries is enormous. In these circumstances, huge heat is also produced from the battery cell. Battery cells are highly susceptible to repeated changes in temperature and battery life is also affected, which is the reason why it is essential to improve efficient thermal management systems for batteries to enhance heat dissipation rate from battery cells. So far several researchers have been working on different Battery Thermal Management Systems (BTMS) to satisfy constraints like rapid charging speeds, high voltage stream, and better efficiency. Such rapid adjustments in the battery had to be closely controlled and managed to prevent thermal and safety-related issues. Active and Passive thermal management is engaged in the battery module to limit the peak battery temperature and peak temperature difference. Phase Change Material (PCM) is employed to dissipate the heat produced in the Passive Thermal Management category, which has a superiority over Active Thermal Management with no power consumption, high heat dissipation density, and isothermal heat transfer. Despite these advances, PCM alone in BTMS is not still easy. The main challenge is to cope up with the low thermal conductance behavior of PCMs. To address this challenge, various high thermal conductive materials are incorporated with PCM. In this chapter, thermal conductivity enhancers are mentioned along with their impact on the performance or efficiency of BTMS.KeywordsBattery thermal management system (BTMS)Phase change material (PCM)Thermal conductivity enhancerMaximum temperature of battery cellComposite phase change material (CPCM)

Recent advancements in battery thermal management system (BTMS): A review of performance enhancement techniques with an emphasis on nano-enhanced phase change materials

Excessive heat generation in lithium-ion batteries during high C-rate operation can accelerate degradation, reduce efficiency, and compromise safety, underscoring the need for effective thermal management strategies. Phase change material (PCM)-based passive battery thermal management systems (BTMS) are attractive due to their latent heat storage capability; however, their low thermal conductivity necessitates enhancement techniques such as fins. In this study, a three-dimensional numerical model employing the enthalpy-porosity method is developed to examine the thermal behaviour of cylindrical cells integrated with PCM and aluminium fins. Both plate and pin fin geometries are systematically investigated at thermal conductivity enhancer (TCE) fractions of 4.78 %, 9.55 %, and 14.33 %, and additional simulations are performed for varying fin thickness at constant volume fraction. A performance metric, termed the “enhancement ratio,” is introduced to relate thermal conduction improvement to PCM endurance. Results indicate that pin fins with 9.55% volume fraction and 1 mm thickness achieve the most effective balance between heat transfer enhancement and latent heat storage, enabling extended safe operation under high C-rates. The findings provide practical design guidelines and a quantitative framework for optimizing PCM-fin structures in advanced BTMS in elective vehicle (EV) and stationary energy storage applications.

Thermal performance enhancement of a passive battery thermal management system based on phase change material using cold air passageways for lithium batteries

Effect of nano-enhanced phase change material on the thermal management of a 18650 NMC battery pack

Efficient thermal management of high‐power lithium‐ion batteries (LiBs) is critical for ensuring safety, longevity, and performance in electric vehicles (EVs). Battery thermal management systems (BTMS) play a crucial role in regulating temperature, as LiBs are highly sensitive to thermal fluctuations. Excessive heat generation during charging and discharging can degrade battery performance, reduce lifespan, and pose safety risks. Traditional cooling methods, such as air and liquid cooling, often require additional power and complex components, making them less effective for high‐energy–density batteries. As a result, recent advancements focus on immersion, indirect, and hybrid cooling solutions. Among these, phase change material (PCM)‐based BTMS has emerged as a promising passive cooling approach. PCMs efficiently absorb and store heat, maintaining optimal battery temperature without external power. Their thermal performance is further enhanced by integrating expanded graphite (EG) fillers, metal foams, or fins, improving heat dissipation. This review examines recent progress (2019–2024) in BTMS technologies, with a particular focus on PCM applications in fast‐charging conditions. It also discusses BTMS performance under extreme environments, such as high temperatures, sub‐zero conditions, and abuse scenarios. Future research directions are highlighted to optimize BTMS for next‐generation EVs, ensuring improved battery safety, efficiency, and thermal stability.

Recent developments in the passive and hybrid thermal management techniques of lithium-ion batteries

Steady and transient sensitivity investigations on a passive battery thermal management system coupling with phase change materials and heat pipes: Full numerical modeling and orthogonal tests

Effect of structural characteristics and surface functional groups of biochar on thermal properties of different organic phase change materials: Dominant encapsulation mechanisms