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Composite phase change materials (PCMs) consisting of thermally conductive nanofillers and a PCM matrix can provide an effective buffer for battery packs to avoid thermal runaway. However, there remain some challenges to overcome the trade-off between thermal conductivity and phase change enthalpy. Herein, we developed a bidirectionally high thermal conductive composite PCM featuring a radially oriented structure using an arrayed radial freezing method. The advanced composite PCM achieves high radial (6.09 W m–1 K–1) and axial thermal conductivities (4.83 W m–1 K–1) while maintaining high phase transition enthalpy (146.7 J g–1), outperforming most reported composite PCMs. Incorporating this composite PCM into a battery pack lowers the battery surface temperature by at least 10 °C and significantly reduces the temperature difference within the battery pack from 6.7 to 1.3 °C. Our approach is versatile with various thermally conductive nanofillers, providing opportunities for developing next-generation battery thermal management materials. [ABSTRACT FROM AUTHOR]

The power battery is a key component of electric vehicles and its performance is greatly affected by temperature. Battery thermal management systems based on phase change materials can effectively control the battery temperature and at the same time have the advantages of simple structures, energy savings, and good temperature uniformity, and has broad development prospects. In this paper, expanded graphite–paraffin composite phase change materials were prepared, phase change material cooling experiments were carried out, and a phase change material cooling simulation model was also established using the Fluent software to study the influence of phase change material thermophysical parameters on thermal management performance. The results show that the phase change material thermal management method has excellent cooling performance. The best thermal management performance is achieved at the 3C discharge rate, with a phase change material filling thickness of 4 mm, a melting point of 40 °C above ambient temperature, and a thermal conductivity of 3 W/(m·K). When the phase change latent heat was increased from 150 J/g to 250 J/g, the liquid phase ratio decreased from 0.84 to 0.51, and the subsequent cooling performance was greatly improved, so the phase change latent heat should be increased as much as possible. [ABSTRACT FROM AUTHOR]

Lithium battery temperatures will increase if the heat produced during the charging and discharging procedures is not promptly vented externally. Fewer investigations have been conducted on materials that can retain good flexibility at room temperature and shape stability at high temperatures under the existing thermal management system for phase change materials (PCM). In this study, a particular kind of flexible composite PCM (CPCM) at room temperature is created to address the issue of heat transfer between the PCM and the power battery. The characteristics of hardness, room-temperature flexibility, form stability at high temperature, and thermal conductivity are compared with those of three other thermally induced flexible CPCMs. The flexibility at room temperature of the new CPCM is demonstrated by the results, which makes assembly easier and helps further lower the contact thermal resistance. Charge–discharge test comparisons of the battery modules employing the chosen CPCM and thermally induced CPCM are performed to further evaluate their thermal management capabilities. The thermally induced CPCM exhibits larger maximum temperature profiles at the discharge rates of 1C, 2C, and 3C than the room-temperature flexible CPCM. The variations in maximum temperatures are 0.96, 1.48, and 2.08 °C. [ABSTRACT FROM AUTHOR]

This paper introduces a novel hybrid thermal management strategy, which uses secondary coolants (air and fluid) to extract heat from a phase change material (paraffin), resulting in an increase in the phase change material's heat extraction capability and the battery module's overall thermal performance. A novel cold plate design is developed and placed between the rows and columns of the cells. The cold plate contains a single fluid body to improve the thermal performance of the battery module. Experimental studies were conducted to obtain the temperature and heat flux profiles of the battery module. Moreover, a numerical model is developed and validated using the experimental data obtained. The numerical data stayed within ±2% of the experimental data. In addition, the ability of nanoparticles to increase the thermal conductivity of water is examined and it is found that the cooling from the liquid cooling component is not sensitive enough to capture the 0.32 W/m K increase in the thermal conductivity of the fluid. Furthermore, in order to enhance the air cooling, fins were added within the air duct to the cold plate. However, this is not feasible, as the pressure drop through the addition of the fins increased by ~245%, whereas the maximum temperature of the battery module reduced by only 0.6 K. Finally, when scaled up to an entire battery pack at a high discharge rate of 7 C, the numerical results showed that the overall temperature uniformity across the pack was 1.14 K, with a maximum temperature of 302.6 K, which was within the optimal operating temperature and uniformity ranges. Therefore, the developed thermal management strategy eliminates the requirement of a pump and reservoir and can be scaled up or down according to the energy and power requirements. [ABSTRACT FROM AUTHOR]

A sizable composite phase change material (CPCM) that can be used for battery thermal management is prepared by blending expanded graphite (EG) and boron nitride (BN) with hot melt method and taking polyethylene glycol (PEG1000) as the raw material. The effects of the addition of EG and BN on the thermophysical properties of CPCM were investigated by adjusting the amounts of EG and BN. The chemical structure, phase change characteristics and thermal stability of CPCM were investigated based on infrared spectroscopy, differential scanning calorimetry and thermogravimetric analysis. A thermal conductivity test device was built based on the steady-state method to measure and calculate the thermal conductivity of CPCM. The results show that when the mass fraction of both EG and BN is 5%, the CPCM of PEG1000/5% EG/5 % BN has good thermal stability and the best thermal torage effect, with the latent heat of 126.72 kJ/kg, and the subcooling degree decreasing by 0.63 °C compared with that of PEG1000. The thermal conductivity of PEG1000/5% EG/5 % BN can reach 2.09 W/( m·K), which is 226.6% higher than that of PEG1000, and 27.4% larger than that of PEG1000/5% EG. Overall, PEG1000/5% EG/5% BN has a simple preparation process and a thermal conductivity greater than 2 W/(m·K) and a latent heat greater than 120 kJ/kg, making it suitable for battery thermal management systems. [ABSTRACT FROM AUTHOR]

This study presents the experimental results of the effects on base oils after thermal and electrical aging to determine key parameters of next-generation fluids for thermal management in electric vehicles. The test fluids selected were a mineral base oil API G-III, an API G-IV Polyalphaolefin (PAO), a diester, and a polyolester, all of which had similar kinematic viscosity (KV100 = 4 cSt). All were initially characterized with measurements of density, viscosity, thermal conductivity, specific heat capacity, breakdown voltage, resistivity, and dissipation factor. They underwent two separate aging processes, one thermal, heating the test fluid at 150 °C for 120 h with a copper strip as a catalyst; and the second one an electrical aging process, with the application of 1000 breakdown voltage discharges. The same properties were measured again after each aging process and compared to the initial ones. It was found that the thermal properties ranged with similar values and did not suffer major changes after the aging processes, unlike electrical properties, which vary between samples and after thermal and electrical stress. The insights gained from this study have implications for both the development of next-generation e-thermal fluids and the future standardization of these fluids for EV thermal management applications. The findings of this study underscore the significance of formulating and selecting a suitable dielectric fluid for EV thermal management. By leveraging the insights provided, researchers and engineers can advance in the development of efficient and reliable e-thermal fluids while working towards future standardization to enhance the performance and safety of EV battery systems. [ABSTRACT FROM AUTHOR]

Paraffin phase change materials (PCMs) exhibit great potential in battery thermal management (BTM); nevertheless, their application has been hampered by the handicap of low thermal conductivity, leakage, and volume expansion during phase transition. In this work, ternary composite PCMs formed of paraffin, expanded graphite (EG), and low-density polyethylene (LDPE) were developed for application in BTM. The structure and properties of the composite PCMs were characterized via X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, and thermal constant analysis. The result shows that EG can form a large-size graphite frame as heat conduction paths to improve the thermal conductivity of the composite PCM, and LDPE can form an interpenetrating network within the composite PCM to resist the internal stress of paraffin expansion and prevent deformation. The latent heat and thermal conductivity of the composite PCMs loaded with 10 wt% EG and 4 wt% LDPE can reach 172.06 J/g and 3.85 Wm−1K−1 with a relatively low leakage ratio of 6.2 wt%. Remarkably, the composite PCMs could reduce the temperature rise of the battery by 55.1%. In brief, this work provides a feasible route to develop high-performance PCMs for BTM. [ABSTRACT FROM AUTHOR]

Abstract Phase change materials (PCMs) are expected to achieve dual-mode thermal management for heating and cooling Li-ion batteries (LIBs) according to real-time thermal conditions, guaranteeing the reliable operation of LIBs in both cold and hot environments. Herein, we report a liquid metal (LM) modified polyethylene glycol/LM/boron nitride PCM, capable of dual-mode thermal managing the LIBs through photothermal effect and passive thermal conduction. Its geometrical conformation and thermal pathways fabricated through ice-template strategy are conformable to the LIB’s structure and heat-conduction characteristic. Typically, soft and deformable LMs are modified on the boron nitride surface, serving as thermal bridges to reduce the contact thermal resistance among adjacent fillers to realize high thermal conductivity of 8.8 and 7.6 W m−1 K−1 in the vertical and in-plane directions, respectively. In addition, LM with excellent photothermal performance provides the PCM with efficient battery heating capability if employing a controllable lighting system. As a proof-of-concept, this PCM is manifested to heat battery to an appropriate temperature range in a cold environment and lower the working temperature of the LIBs by more than 10 °C at high charging/discharging rate, opening opportunities for LIBs with durable working performance and evitable risk of thermal runaway.

Nanoencapsulated phase change materials (NePCMs) are promising thermal energy storage (TES) and heat transfer materials that show great potential in battery thermal management systems (BTMSs). In this work, nanocapsules with a paraffin core and silica shell were prepared using an optimized sol-gel method. The samples were characterized by different methods regarding chemical composition, thermal properties, etc. Then, the nanocapsules were used as the coolant by mixing with insulation oil in the immersion cooling of a simulative battery. The sample doped with Ag on the shell with a core-to-shell ratio of 1:1 showed the best performance. Compared to the sample without doping material, the thermal conductivity increased by 49%, while the supercooling degree was reduced by 35.6%. The average temperature of the simulative battery cooled by nanocapsule slurries decreased by up to 3.95 °C compared to the test performed with pure insulation oil as the coolant. These novel nanocapsules show great potential in the immersion cooling of a battery. [ABSTRACT FROM AUTHOR]

Battery pack specific energy, which can be enhanced by minimising the mass of the battery thermal management system (BTMS), is a limit on electric fixed-wing flight applications. In this paper, the use of phase-change materials (PCMs) for BTMSs is numerically explored in the 3D domain, including an equivalent circuit battery model. A parametric study of PCM properties for effective thermal management is conducted for a typical one-hour flight. PCMs maintain an ideal operating temperature (288.15 K–308.15 K) throughout the entire battery pack. The PCM absorbs heat generated during takeoff, which is subsequently used to maintain cell temperature during the cruise phase of flight. In the control case (no BTMS), battery pack temperatures fall below the ideal operating range. We conduct a parametric study highlighting the insignificance of PCM thermal conductivity on BTMS performance, with negligible enhancement observed across the tested window (0.1–10 W m−1 K−1). However, the PCM's latent heat of fusion is critical. Developers of PCMs for battery-powered flight must focus on enhanced latent heat of fusion, regardless of the adverse effect on thermal conductivity. In long-haul flight, an elongated cruise phase and higher altitude exasperate this problem. The unique characteristics of PCM offer a passive low-mass solution that merits further investigation for flight applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • The thermal application of carbon nanotube from waste plastic was firstly studied. • The thermal conductivity of phase change composite material increased by 104%. • Latent heat capacity of phase change composite material retains 90.7%. • The produced carbon nanotube shows similar potential as commercial carbon nanotube. • This phase change nanocomposite is promising for battery thermal management. Carbon nanotube (CNT), has been demonstrated as a promising high-value product from thermal chemical conversion of waste plastics and securing new applications is an important prerequisite for large-scale production of CNT from waste-plastic recycling. In this study, CNT, produced from waste plastic through chemical vapor deposition (pCNT), was applied as a nanofiller in phase change material (PCM), affording pCNT-PCM composites. Compared with pure PCM, the addition of 5.0 wt% pCNT rendered the peak melting temperature increase by 1.3 ℃, latent heat retain by 90.7%, and thermal conductivity increase by 104%. The results of morphological analysis and leakage testing confirmed that pCNT has similar PCM encapsulation performance and shape stability to those of commercial CNT. The formation of uniform pCNT cluster networks allowed for a large CNT loading into the PCM on the premise of free phase change, responsible for the high thermal conductivity inside the homogeneous phase. Thus, the resulting capillary forces retained a high latent heat capacity and suitable melting temperature and prohibited PCM leakage from the matrix to the outside during re-melting as the pCNT loading ratio increased. Therefore, the as-prepared pCNT-PCM composite is believed to have similar potential to cCNT and shows prominent performance as a flowable conductive filler for battery thermal management systems. [ABSTRACT FROM AUTHOR]

Highlights: The phase change materials possess conformable configuration to the structure of Li-ion batteries in macro-scale and multidirectional thermal pathways for rapid and uniform heat transfer in micro-scale. Hierarchically structured phase change materials achieve dual-mode thermal management ability for heating and cooling Li-ion batteries. Excellent practical battery thermal management performance was verified by 18,650 Li-ion batteries in both cold and hot environments. Phase change materials (PCMs) are expected to achieve dual-mode thermal management for heating and cooling Li-ion batteries (LIBs) according to real-time thermal conditions, guaranteeing the reliable operation of LIBs in both cold and hot environments. Herein, we report a liquid metal (LM) modified polyethylene glycol/LM/boron nitride PCM, capable of dual-mode thermal managing the LIBs through photothermal effect and passive thermal conduction. Its geometrical conformation and thermal pathways fabricated through ice-template strategy are conformable to the LIB's structure and heat-conduction characteristic. Typically, soft and deformable LMs are modified on the boron nitride surface, serving as thermal bridges to reduce the contact thermal resistance among adjacent fillers to realize high thermal conductivity of 8.8 and 7.6 W m−1 K−1 in the vertical and in-plane directions, respectively. In addition, LM with excellent photothermal performance provides the PCM with efficient battery heating capability if employing a controllable lighting system. As a proof-of-concept, this PCM is manifested to heat battery to an appropriate temperature range in a cold environment and lower the working temperature of the LIBs by more than 10 °C at high charging/discharging rate, opening opportunities for LIBs with durable working performance and evitable risk of thermal runaway. [ABSTRACT FROM AUTHOR]

In this work, we develop a hybrid battery thermal management (BTM) system for a 7 × 7 large battery module by coupling an epoxy resin (ER)-enhanced phase change material (PCM) module with internal liquid cooling (LC) tubes. The supporting material of ER greatly enhances the thermal stability and prevents PCM leakage under high-temperature environments. In addition, the other two components of paraffin and expanded graphite contribute a large latent heat of 189 J g−1 and a high thermal conductivity of 2.2 W m−1 K−1 to the PCM module, respectively. The LC tubes can dissipate extra heat under severe operating conditions, demonstrating effective secondary heat dissipation and avoiding heat storage saturation of the module. Consequently, during the charge-discharge tests under a 40 °C ambient temperature, the temperature of the PCM-LC battery module could be maintained below 40.48, 43.56, 45.38 and 47.61 °C with the inlet water temperature of 20, 25, 30 and 35 °C, respectively. During the continuous charge-discharge cycles, the temperature could be maintained below ~48 °C. We believe that this work contributes a guidance for designing PCM-LC-based BTM systems with high stability and reliability towards large-scale battery modules. [ABSTRACT FROM AUTHOR]

Summary: The phase change material is currently being regarded as an effective cooling media to be applied in the thermal management of lithium batteries‐powered vehicles, in which the inorganic hydrate phase change material is desirable and widely investigated due to the high thermal conductivity, latent heat value, and low cost. However, when applied to thermal energy storage applications, supercooling and phase separation are problematic. To effectively circumvent this issue, this work considers utilizing the disodium hydrogen phosphate dodecahydrate as the matrix of the composite phase change material, as the phase transition temperature is suitable for the battery's operating temperature range. Meanwhile, the nucleating agent sodium metasilicate nonahydrate with similar lattice parameters and the thickener carboxymethyl cellulose are used to suppress the supercooling and eliminate the phase separation, respectively. Effects of nucleating agent, surface modified aluminum nitride, and short‐cut carbon fiber on the supercooling degree, and thermal conductivity and curing performance in the phase change material are evaluated and discussed in detail to determine the optimal preparation scheme for Na2HPO4·12H2O/modified AlN/CF inorganic composite phase change materials. Experimental results show that the addition of 4 wt% Na2SiO3·9H2O, 4 wt% CMC, 12 wt% modified AlN, and 6 wt% CF reduces the supercooling degree of the composite phase change material to 1.9°C and increases the thermal conductivity to 1.86 W/(m·K). The composite phase change material is found to have a suitable phase change temperature (35°C), high latent heat (249 J/g), excellent shaping effect, and electrical safety performance. In addition, the composite phase change material battery module can effectively control the battery's temperature, with the maximum temperature reduced by 40.9°C at 3C discharge rate and 30°C ambient temperature compared with the natural cooling battery module. The maximum temperature difference of the composite phase change material battery module is shown to be reduced to the minimum value of 0.9°C. Highlights: A novel disodium hydrogen phosphate dodecahydrate—modified aluminum nitride—carbon fiber composite phase change material is designed and prepared for battery thermal management systems.The antiwater modification scheme of AlN is proposed and assessed. The effects of AlN before and after modification on the thermal properties of CPCM are compared.The joint use of nucleating agent sodium metasilicate nonahydrate and thermal conductive filler AlN contributes to significantly inhibiting the supercooling of hydrate salt.The addition of CF can effectively increase the thermal conductivity of CPCM and prevent its leakage.CPCM has suitable phase change temperature, high thermal conductivity and latent heat value, excellent electrical safety, and stable curing performance.The battery test bench is constructed and the discharge test of the CPCM battery module is carried out. The results show that the CPCM battery module has excellent cooling performance and temperature uniformity. [ABSTRACT FROM AUTHOR]

This study presents the experimental results of the effects on base oils after thermal and electrical aging to determine key parameters of next-generation fluids for thermal management in electric vehicles. The test fluids selected were a mineral base oil API G-III, an API G-IV Polyalphaolefin (PAO), a diester, and a polyolester, all of which had similar kinematic viscosity (KV100 = 4 cSt). All were initially characterized with measurements of density, viscosity, thermal conductivity, specific heat capacity, breakdown voltage, resistivity, and dissipation factor. They underwent two separate aging processes, one thermal, heating the test fluid at 150 °C for 120 h with a copper strip as a catalyst; and the second one an electrical aging process, with the application of 1000 breakdown voltage discharges. The same properties were measured again after each aging process and compared to the initial ones. It was found that the thermal properties ranged with similar values and did not suffer major changes after the aging processes, unlike electrical properties, which vary between samples and after thermal and electrical stress. The insights gained from this study have implications for both the development of next-generation e-thermal fluids and the future standardization of these fluids for EV thermal management applications. The findings of this study underscore the significance of formulating and selecting a suitable dielectric fluid for EV thermal management. By leveraging the insights provided, researchers and engineers can advance in the development of efficient and reliable e-thermal fluids while working towards future standardization to enhance the performance and safety of EV battery systems.

Paraffin phase change materials (PCMs) exhibit great potential in battery thermal management (BTM); nevertheless, their application has been hampered by the handicap of low thermal conductivity, leakage, and volume expansion during phase transition. In this work, ternary composite PCMs formed of paraffin, expanded graphite (EG), and low-density polyethylene (LDPE) were developed for application in BTM. The structure and properties of the composite PCMs were characterized via X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, and thermal constant analysis. The result shows that EG can form a large-size graphite frame as heat conduction paths to improve the thermal conductivity of the composite PCM, and LDPE can form an interpenetrating network within the composite PCM to resist the internal stress of paraffin expansion and prevent deformation. The latent heat and thermal conductivity of the composite PCMs loaded with 10 wt% EG and 4 wt% LDPE can reach 172.06 J/g and 3.85 Wm−1K−1 with a relatively low leakage ratio of 6.2 wt%. Remarkably, the composite PCMs could reduce the temperature rise of the battery by 55.1%. In brief, this work provides a feasible route to develop high-performance PCMs for BTM.

Summary: Phase change material (PCM) based battery thermal management system (BTMS) provides even heat distribution and lower maximum temperature, but it suffers from low thermal conductivity. In this study, the impact of graphene additive on PCM was analyzed by presenting three experiments with various structures to solve PCM's low thermal conductivity problem. The results demonstrate that there is no positive impact of graphene additive in the first and third structures. The PCM‐graphene additive between the second structure's fins significantly improves the battery heat transfer by allowing the battery to cool down 1500 seconds earlier than the graphene‐free structure. Moreover, a thermal equivalent circuit model was derived for the second structure because of its enhanced performance. It is shown that the model works accurately and proves its ability to control not only temperature fluctuations but also transient behavior of the battery. This model provides that the battery temperature can be analyzed without experimentation for different charge‐discharge scenarios in lithium‐ion batteries with a shorter computation time. [ABSTRACT FROM AUTHOR]

To address the bottleneck of easy leakage and low thermal conductivity of phase change materials (PCMs) for battery thermal management. Phase change composite (PCCs) with paraffin (PA) as the PCM, styrene ethylene butylene styrene (SEBS) as the supporting skeleton, and boron nitride (BN) as the thermally conductive filler were fabricated by the sacrificial template method. Compared with the composite prepared by melt-blending method, the thermal conductivity of PCC was improved by 27.6 % and the leakage rate was reduced by 82.4 % because the BN was rubbed with Na 2 SO 4 under the shear provided by internal mixer. As a result, the maximum temperature and maximum temperature difference of the battery pack with PCC cooling were 35.8 % and 62.5 % lower than those without PCC cooling at 2C discharge rate. In total, this work offers a strategy for improving the thermal conductivity and the leakage-proof ability of PCCs as well as for large-scale fabrication. [Display omitted] • The SEBS-BN@PA composites are prepared by the sacrificial template method. • The prepared composites have good leakage-proof ability and shape stability. • The composite has higher thermal conductivity than those prepared by melt-mixing method. • The composite presents excellent performances for battery thermal management. [ABSTRACT FROM AUTHOR]

Efforts to mitigate environmental pollution from the use of petroleum-based energy sources have promoted research on rechargeable secondary batteries for applications such as electric vehicles and energy storage systems. In this context, Li-ion batteries have attracted significant interest. Notably, the thermal management of such batteries is crucial for achieving a stable output and long lifespan and reducing the risk of thermal runaway. Despite extensive exploration of various cooling schemes, thermal management techniques for Li-ion batteries continue to face challenges due to the high thermal resistance resulting from low thermal conductivity of thermal interfacial materials and inadequate convective heat transfer. Therefore, this study is aimed at using laser-induced graphene (LIG) to enhance the heat transfer characteristics and battery thermal management. LIG is applied through direct laser irradiation on the polyimide substrate of a LiFePO 4 battery. Thermal tests conducted under a discharge rate of 5C demonstrate that immersion cooling using HFE-7000 on the LIG surface substantially reduces the temperature increase by up to 84.3% compared with conventional air cooling. In addition, immersion cooling with LIG surfaces results in outstanding cooling performance through nucleate boiling, attaining a maximum temperature of 37.5 °C, which is lower than that (43.5 °C) on a pristine polyimide surface. Overall, this research provides valuable insights into the thermal management of high-performance batteries operating under extreme conditions, such as high-speed charging, high-power discharging, and high-temperature conditions, with significant implications for future applications. • Introducing laser-induced graphene (LIG) for novel immersion, boiling cooling. • Various aspects of battery behavior were investigated, including discharge rates, working fluids, and temperatures. • LIG-coated battery enhances thermal performance, especially in high-temperature and high C-rate conditions. • LIG-coated battery exhibited a remarkable temperature reduction of up to 84.3%. [ABSTRACT FROM AUTHOR]

In recent years, there has been a growing demand for electrical vehicles, which are more energy efficient and environmentally friendly than their traditional counterpart. One of the crucial aspects of electrical systems is energy storage. A promising option for energy storage is Lithium-ion batteries (LIBs) due to their high energy density, longer life cycles, and faster charging when compared to other batteries. The disadvantage of employing LIBs is that they are more difficult to maintain because they are more prone to failure, and they are greatly dependent on the system's thermal behavior, which has led to an emphasis in research on battery thermal management systems (BTMSs). The BTMS aims to address this issue by limiting the temperature fluctuation of the battery cells to maintain the average temperature within recommended limits throughout the charging and discharging processes. There has been a continuous interest in nanofluids and phase change materials (PCMs) because of their unique properties and their potential thermal application as a cooling medium for high-density batteries. Recent studies have aimed to use different active and passive methods with varying materials and cooling system geometries to achieve the highest possible thermal performance. The current review aims to outline the recent studies on thermal management systems for LIBs. Three main sections have been presented in this paper. The first section reviewed studies on nanofluids in different BTMSs, the other one highlighted techniques adopted to overcome the low thermal conductivity drawback in PCMs for BTMs, and the last one focuses on the effects of combining both cooling approaches. We believe that the present review paper provides useful information that could be a significant step toward developing high-performance BTMS. • A summary of the most recent research on BTMS of LIBs. • Nanofluids and PCM-based BTMS attract significant interest in LIBs. • PCM with carbon additives enhance LIB pack temperature uniformity. • Incorporation of fins has demonstrated effectiveness in improving BTMS performance. • Metal foams with PCMs enhance BTMS performance via improved thermal conductivity. [ABSTRACT FROM AUTHOR]

The demand for high energy density in lithium-ion battery packs for electric vehicles poses a challenge to maintaining its optimum operating temperature while reducing the risk of thermal runaway (TR) propagation. This study proposes a novel hybrid TR propagation mitigation system that balances heat transfer and thermal insulation requirements using low and high thermal conductivity phase change materials (PCM), heat pipes (HP), and air-cooling. The design and optimization of such a mitigation system are complex due to the many design parameters involved. The Adaptive-Kriging-High dimensional model representation (Adaptive-Kriging-HDMR) is used to establish a surrogate model of the system, and the sensitivity of the system's design parameters is evaluated with the maximum battery temperature and the system weight as the targets, thereby improving the efficiency of model calculation and reducing the dimension of optimization parameters. Then, the design of the sensitive parameters is optimized using an extended elitist non‐dominated sorting genetic algorithm (E-NSGA-II) multi-objective optimization algorithm. The results show that the modeling difficulty and optimization calculation time are significantly reduced by using a surrogate model. The calculation time for a single surrogate model only takes a few seconds instead of several hours for the original three-dimensional heat transfer and flow calculation. The thermal conductivity of high thermal conductivity-PCM, the distance between battery and low thermal conductivity-PCM, the battery spacing, and the HP length significantly affect the system. The optimized system substantially reduces the overall weight of the battery system while ensuring its good heat dissipation capability. In the case of TR in a single battery, the system succeeds in limiting the TR propagation to the same row, with the maximum battery temperature in the second row being only 64.3 °C, well below the battery TR trigger point. Under more severe conditions, such as TR occurring in two batteries simultaneously, the maximum battery temperature in the second row is 155.5 °C, and no TR spreads to the adjacent row. This study provides a rapid and effective method for designing a TR propagation mitigation system. It can serve as a reference for the engineering design and optimization of battery thermal management systems. [ABSTRACT FROM AUTHOR]

In this work, we develop a hybrid battery thermal management (BTM) system for a 7 × 7 large battery module by coupling an epoxy resin (ER)-enhanced phase change material (PCM) module with internal liquid cooling (LC) tubes. The supporting material of ER greatly enhances the thermal stability and prevents PCM leakage under high-temperature environments. In addition, the other two components of paraffin and expanded graphite contribute a large latent heat of 189 J g−1 and a high thermal conductivity of 2.2 W m−1 K−1 to the PCM module, respectively. The LC tubes can dissipate extra heat under severe operating conditions, demonstrating effective secondary heat dissipation and avoiding heat storage saturation of the module. Consequently, during the charge-discharge tests under a 40 °C ambient temperature, the temperature of the PCM-LC battery module could be maintained below 40.48, 43.56, 45.38 and 47.61 °C with the inlet water temperature of 20, 25, 30 and 35 °C, respectively. During the continuous charge-discharge cycles, the temperature could be maintained below ~48 °C. We believe that this work contributes a guidance for designing PCM-LC-based BTM systems with high stability and reliability towards large-scale battery modules.

The era of electric mobility has started, and petrol/diesel vehicles are being replaced by electric vehicles (EVs). The phase change material (PCM) is a trending field of research in its application of energy storage and thermal management. PCM-based thermal management method is found to be quite simple and effective for battery packs. However, its commercialization is difficult due to its low thermal conductivity and extra weight addition to the battery pack. Hence, the present research focuses on the battery performance with PCM. The experimental setup for a 48V, 25Ah battery pack is developed, and its performance is explored with and without PCM. The numerical model for same sized battery pack is developed, and validated with experimental results. The major objective of the present research is to find the optimal gap between two battery cells so that a sufficient amount of PCM can be filled inside the battery pack. Initially, inline and staggered cell arrangements are examined, and no significant difference in thermal performance is found. Further, cell spacing of 5 mm, 3 mm, and 1 mm are examined, and maximum temperature and temperature difference are compared along with the weight and volume of the battery pack. For a single charging process, 1 mm cell spacing is found sufficient, considering the weight of the battery pack and thermal performance. However, with 1 mm cell spacing, temperature increases significantly after each charging and discharging. At the same time, 3 mm and 5 mm are found as feasible solutions considering single and double charging-discharging cycles, respectively. 3 mm cell spacing is better option when weight is a critical issue, while 5 mm cell spacing is better when thermal performance is a critical issue. The current study offers guidance in the advancement of battery packs, particularly in cases where space constraints are a concern. • The research focuses on utilization of optimal amount of PCM. • The battery charging experiments are carried out on 48V, 25Ah battery pack. • PCM OM42 reduced battery temperature by 18 %. • The inline and staggered arrangements are found equally effective. • 3 mm cell spacing is found sufficient with limited weight increment. [ABSTRACT FROM AUTHOR]

Summary: Adding thermally conductive filler to polymer matrix is a workable way to increase its thermal conductivity. In this work, carbon fiber (CF) and hexagonal boron nitride (h‐BN) were employed to obtain hybrid fillers, firstly, (mh‐BN@CF) by electrostatic self‐assembly method, then added mh‐BN@CF to silicone rubber (SR) matrix to prepare mh‐BN@CF/SR composites. There was a good interface compatibility between mh‐BN@CF and SR matrix. Besides, the composites can achieve best thermal conductivity when h‐BN and CF are at the optimal fill ratio. When the mass ratio of h‐BN:CF is7:3 and the filling content is 54 phr, the thermal conductivity of mh‐BN@CF/SR can reach 1.3 W/(m K), and it is 23.7% and 400.4% larger than the mixed‐filled h‐BN/CF/SR composites and SR matrix, respectively. Simultaneously, the mh‐BN@CF/SR composites also exhibited good electrical insulation, mechanical properties, and thermal stability. Finally, the prepared composites are used in a liquid‐cooled battery thermal management system (BTMS). The effect of the composites on the performance of the BTMS is discussed by numerical method. The results show that the improved thermal conductivity of the composites can highly reduce the temperature of the battery cells. The prepared composites can highly enhance the performance of BTMS. [ABSTRACT FROM AUTHOR]

• A computationally efficient model for large-scale battery packs is developed. • Parameters are devised to evaluate the structural designs for the battery pack. • Pros and cons of the alternative structural designs are analyzed. • Interspersed battery pack design is suggested to enhance the thermal performance. In this paper, a comparative study for structural design of battery thermal management system is presented for electric vehicles. A thermal model for the pouch battery pack with liquid cooling is developed for thermal analysis of various pack designs. Typical battery pack with fin-cooling structure is set as a reference design, and thermal behavior of the battery pack is examined in the aspect of cooling performance and temperature uniformity. Numerical results indicate that poor heat conductivity from the bottom of the cell stack to the cooling plate is one of the major barriers to the efficient heat dissipation and asymmetric design of fin-cell arrangement have negative effect on the temperature uniformity of the battery pack. To improve the performance of the thermal management system, various structural designs are suggested and evaluated based on plural criteria. A new structural design for the large-scale battery pack is suggested to enhance the cooling performance and temperature uniformity of the battery pack minimizing the increase in system volume, weight, and pressure drop. [ABSTRACT FROM AUTHOR]

Abstract Battery thermal management is of great significance for increasing the thermal safety and prolonging the service life of the electric vehicle battery pack. In this paper, the thermal property of pouch Lithium-ion battery module cooled by PCMs (Phase Change Materials) was investigated. The three-dimensional thermal models of battery modules consisted of different thickness batteries were established to study the effects of space between adjacent batteries, melting point and thermal conductivity of PCMs on cooling performance. The results showed that the T max (maximum temperature) and ΔT max (maximum temperature difference) declined when space between modules and thermal conductivity of PCMs increased. And the decline became more obviously with the increasing melting point of PCMs. T max increased and ΔT max declined as the melting point of PCMs increased. On the basis of the T max of battery module meeting the temperature requirements, improving the space between adjacent batteries, melting point and thermal conductivity of PCM properly contributed to enhance the conformity of temperature filed. The conclusion would contribute to the design of battery thermal management system based on PCMs. [ABSTRACT FROM AUTHOR]

Aiming at the problems of irreversible decay and shortened life of the battery caused by high temperature during the operation of power battery pack, a novel composite phase change material based on metal-organic framework (MOF) was proposed in this work. MIL-101-NH 2 , an amino functionalized MOF material, was grown in situ on expanded graphite (EG) to synthesize hierarchical structure-based loading material for efficient loading of phase change material lauric acid (LA). The microstructure and structure of the composite phase change materials, thermal properties such as phase change temperature and latent heat, thermal conductivity, thermal stability, thermal cycling properties, as well as thermal stability and thermal cycling properties were tested. The results show that amino functionalization of the loading materials is helpful to further improve the loading rate and latent heat of the composite phase change materials. LA/MIL-101-NH 2 and LA/EG@MIL-101-NH 2 can be loaded up to 70% and have high phase change latent heat (97.74 J/g and 94.55 J/g). When applied to battery thermal management, LA/EG@MIL-101-NH 2 can reduce the battery temperature by 4.5–22.3% under the discharge conditions of 1C, 2C, 3C, 4C and the cycle condition, and keep the safe temperature below 50 °C, which provides a new idea for passive thermal management of batteries. • A composite phase change material based on metal-organic skeleton is proposed. • Thermophysical parameters of composite phase change materials is tested. • A new idea for passive thermal management of batteries is provided. [ABSTRACT FROM AUTHOR]

Thermal management of power battery is important to ensure the safety of electric vehicle. Coupling phase change materials (PCMs) with liquid cooling technology is an efficient temperature uniformity strategy. In this paper, a self-made microencapsulated PCM (MPCM) was used to prepare MPCM slurry (MPCMS), and three base liquids (water, ethanol, and silicone oil) were evaluated, which confirmed that the silicone oil could maintain slurry without sedimentation for 7 days, providing the best stability. Also, graphene (GE) was introduced to increase the heat transfer rate of slurry. Then the prepared slurries were applied to the prismatic lithium-ion battery module to verify their thermal management performance. The results indicated that the prepared slurries' latent heat, thermal conductivity, and specific heat capacity were all rose with the increase of MPCM concentration. In addition, the slurries' viscosity changed little when the concentration was below 40 wt%. Compared with the blank module, GE-MPCMS-Si could reduce the battery module temperature and the temperature variance by 14.49 °C and 3.8 °C2, respectively. Besides, the influence of flow rate was further investigated, which showed 6 mL/s is the most economical and efficient flow rate option. • Phase change microcapsule slurry was prepared for battery thermal management. • The stabilities of slurries with three base liquids were compared. • The thermal performance of the slurry was raised by introducing graphene. • Prepared slurry can reduce the maximum temperature and improve uniformity. [ABSTRACT FROM AUTHOR]

Driven by the development of electric vehicles, there is an unmet need to protect power battery from sharp temperature rise and thermal runaway. This study aims to design a new type of composite phase change material for thermal management of battery. By adsorption of lauric acid (LA), LA/EG@HPC composite phase change material with stable shape can be obtained. The BET surface area of the carrier is 15.9326 m2/g, and the pore size distribution is mainly mesoporous and macroporous. The three-dimensional structure of the carrier can provide a continuous layered heat transfer network channel for LA. The load rate of the composite phase change material can be up to 70%, and the thermal conductivity is 2.546 W/(m·K), 8.4 times that of pure LA. In addition, currently MOF materials used in phase change material carrier are synthesized by reaction kettle. The solvothermal method adopted in this study can greatly improve the single synthesis yield and is easy to operate. The composite phase change material shows excellent performance in the thermal management of batteries. In the discharge test of different rates, the maximum temperature of the battery pack is reduced by 13.4 °C compared with that of the battery pack without thermal management, the temperature difference of the battery is reduced by 1–1.5 °C, and the operating temperature is far lower than the safe temperature of 50 °C. During the cycle test, the temperature fluctuation of composite phase change material group is reduced by 45% under DST condition, and the temperature of the battery under constant high rate condition is maintained below the safe temperature, which has a remarkable thermal management effect. • LA/EG@HPC composite phase change material with stable shape was obtained. • Solvothermal method was used to improve the single synthesis yield. • Novel composite phase change material was used in the thermal management of batteries. [ABSTRACT FROM AUTHOR]

• Flexible phase change material (FPCM) with shape memory property is proposed. • The flexibility of FPCM could be maintained at −15 to 60 °C. • A sleeve with a heat shrink function for easy assembly and reduced TCR is designed. • Room-temperature FPCM is superior in reducing thermal contact. The development of conventional battery thermal management (BTM) based on phase change material (PCM) is restricted by its low thermal conductivity, leakage and high rigidity. To solve these problems, the thermally induced flexible phase change materials (FPCMs) have been proposed, but their flexibility only manifests at temperatures above the phase change temperature, which is detrimental to the assembly at room temperature. Herein, using paraffin (PA) as PCM, thermoplastic polyether ester elastomer (TPEE) as flexible support material and expanded graphite (EG) as heat transfer enhancement material, a novel FPCM with shape memory property and wider flexible temperature (−15 to 60 °C) was successfully prepared through melt-mixing method. And then it was skillfully assembled on power batteries at room temperature through flexibility in conjunction with shape memory property. On this basis, the flexibility of FPCM can be utilized to reduce thermal contact resistance during the whole process of battery operation. The results revealed that the measured thermal contact resistance of the above BTM was 0.272 °C/W, lower than that of previous thermally induced FPCM reported. Furthermore, the maximum temperature of the battery module with the passive BTM based on FPCM could be maintained below 55 °C and the temperature difference was within 3 °C under the high discharge rate of 5C and 40 °C ambient temperature. [ABSTRACT FROM AUTHOR]

Phase change material as the core of latent heat energy storage technology, suffers from the "solid-liquid phase change" problem. In this study, "solid-solid" composite phase change materials (CPCMs) have been developed using olefin block copolymers (OBC) and decanoic acid. With ≥30 wt% OBC, the physical shapes of the developed CPCMs nearly remain unchanged after 100 times of thermal cycling, without significant changes in the phase change properties. The addition of graphite powder leads to a significant enhancement in thermal conductivity of up to 18 times, which leads to excellent control of battery maximum temperature and temperature uniformity. In the battery thermal management test, the developed CPCM achieves a maximum of 3 °C and 10.5 °C reductions in maximum temperature difference and peak temperature, respectively. The CPCMs also prolong the thermal preservation time by 3 times. In the pack level test, the use of CPCM plates leads to a maximum temperature reduction of 15 °C on the commercial battery pack under 55 °C extreme working temperature. • CPCMs retain their shape and properties after 100 times of thermal cycling. • The thermal conductivity of the CPCMs were improved by up to 8 times. • 10.5 °C of peak temperature reduction was achieved with the CPCM. • The developed CPCMs prolonged the thermal preservation time by ∼3 times. [ABSTRACT FROM AUTHOR]

As an important method for battery thermal management, traditional phase change material (PCM) technology is facing challenges due to the relatively low thermal conductivity, weak skeleton strength and/or leakage phenomenon of PCM. Herein we develop a copper mesh (CM)-enhanced paraffin (PA)/expanded graphite (EG) composite as a composite PCM for battery thermal management. EG with porous structure can absorb liquid phase PA, preventing PA leakage. CM acts as a skeleton to further enhance both the thermal conductivity and strength of the whole module. As a result, the as-constructed CM enhanced PCM of PA/EG plate (PCMP) presents much better heat dissipation performance and temperature uniformity compared to PCMP without CM, especially in harsh working conditions. Moreover, with forced air convection, copper fins exposed from the composite may play a crucial role in not only heat dissipation, but also disturbing the air flow, and thus further strengthen the heat transfer capability. [ABSTRACT FROM AUTHOR]

• Composite PCM is designed by in-situ constructing phase changeable framework in PEG. • The novel composite PCM possesses dual phase change temperature regions (PCTRs). • The two PCTRs are precisely tailored at 31.7–42.1 ℃ and 42.1–51.2 ℃, respectively. • The lower PCTR ensures suitable working temperature for battery at normal operation. • The higher PCTR prevents thermal hazards of battery under high ambient temperature. The phase change material (PCM)-based battery thermal management technology still remains a contradiction of guaranteeing a suitable operating temperature (20–40 ℃) of the batteries under regular working conditions, while avoiding the malfunction of the PCM under high ambient temperature (>40 ℃). Therefore, a novel composite PCM (CPCM) possessing dual phase change temperature regions (PCTRs) is designed herein by in-situ constructing a phase-changeable polymer (PCP) framework in the polyethylene glycol (PEG)/expanded graphite (EG) slurry. As prepared, the lower PCTR at 31.7–42.1 ℃ from the PCP framework provides a latent heat of 35.0 J g−1, while the higher PCTR at 42.1–51.2 ℃ from the PEG offers a latent heat of 68.3 J g−1. Additionally, the nanoscaled PCP framework strongly adsorbs the PEG, preventing the leakage phenomenon (mass loss < 1%), and the uniformly dispersed EG endows the CPCM with a high thermal conductivity of 1.98 W m−1 K−1. In consequence, under the normal ambient temperature of 25 ℃, the lower PCTR effectively keeps the battery module operating within the suitable temperature range of 25.9–34.9 ℃ and with a low temperature difference (ΔT) of 2.4 ℃ at the discharge rate of 1C. For comparison, the battery module adopting classical CPCM with a single PCTR at 40.9–55.1 ℃ demonstrates a much higher temperature range and maximum ΔT at 28.0–40.9 ℃ and 4.8 ℃, respectively. Under the high ambient temperature of 40 ℃, the higher PCTR starts to work like the single PCTR of traditional CPCMs, and controls the T max and ΔT of the module below 49.2 and 2.2 ℃ at the discharge rate of 1C, respectively, preventing thermal hazards. [ABSTRACT FROM AUTHOR]

The development of phase change materials with a high latent heat of fusion and thermal conductivity is a key issue that needs to be addressed in power batteries thermal management system. In this study, an imidazolium ionic liquid ([C 16 MIM]Br) suitable for latent heat storage was synthesized by quaternization reaction. The composite phase change material of ionic liquid/graphene/carbon nanotube aerogel was prepared by hydrothermal self-assembly and vacuum impregnation method utilizing the unique π-π interaction between the delocalized electron of the heterocyclic cation of the ionic liquid and the sp2 bonded carbon materials. The prepared ionic liquid-based phase change materials had high latent heat of phase change, excellent thermal stability, and enhanced thermal conductivity. The thermal conductivity of the composite material reached 0.751 W/(m·K) at a carbon nanotubes addition of 15 wt%, which was 232% higher than that of the pure ionic liquid (0.226 W/(m·K)). The enhancement was attributed to the three-dimensional network in the graphene/multi-walled carbon nanotubes aerogel which was beneficial to improve the dispersion of multi-walled carbon nanotubes in the matrix and promote the uniform penetration of the ionic liquid phase change material. As a result, the designed structure provided effective ways for phonon transmitting and improved the thermal conductivity of the composites. • Phase change temperature and enthalpy of fusion of ionic liquid were investigated. • Graphene aerogel promoted the dispersion of carbon nanotubes. • The interactions between the ionic liquid matrix and the additives were clarified. • The three-dimensional graphene structure improved the thermal conductivity. [ABSTRACT FROM AUTHOR]

Battery thermal management (BTM) plays a significant role in the safety and reliability of autonomous underwater vehicles (AUV) at higher speeds. In this study, a nanoparticle/phase change material (nano-PCM) composite is proposed for the BTM of an AUV. The effects of nanoparticle loading percentage (φ = 5, 10, and 15%) and nanoparticle filling range (α = 30, 60, 90, and 120°) on the battery temperature and PCM melting were investigated numerically. Two criteria for the dimensionless temperature control performance (TCP) factor and dimensionless heat storage performance (HSP) factor were used to evaluate the influence of various variables on the BTM performance. The results show that increasing the nanoparticle loading percentage improves the effective thermal conductivity of the PCM but reduces the overall effective latent heat. An optimal nanoparticle filling range of α = 60° is recommended to accelerate the overall melting rate of the PCM. Compared with those of the pure PCM-based BTM, the TCP rate and TCP density are enhanced by 14.56% and 26.75%, respectively, at α = 60°. The HSP rate increases by 2.84% but the HSP density reduces by 11.85% at α = 60°. These findings can provide a reference for the accurate design of nano-PCM composites for the BTM of AUVs. [ABSTRACT FROM AUTHOR]

With the large latent heat and low cost, the paraffin has been widely used in battery thermal management (BTM) system to improve the efficiency and cycling life of power battery. The numerical model of paraffin melting in a cavity has been established, and the effects on the solid-liquid phase change process have been investigated for the purpose of enhancing the heat transfer performance of paraffin-based BTM system. The results showed that the location of the heating wall had great effects on the melting process. The paraffin in the cavity melted most quickly when the heating wall located at the bottom. Furthermore, the effects of thermal conductivity and the velocity of the slip wall have been considered. The gradient of liquid fraction increased with the increase in thermal conductivity, and the melting process could be accelerated or delayed by the slip wall with different velocity. [ABSTRACT FROM AUTHOR]

In order to extend the cycle life of power battery pack within electric vehicle, a phase change material (PCM)/mini-channel coupled power battery thermal management (BTM) system, as well as the three-dimensional battery thermal model, was designed in this paper. The effect of various influencing factors, especially mass flow rate of water, phase change temperature and thermal conductivity of PCM, were investigated numerically. The results showed that the liquid volume fraction of PCM was greatly influenced by the thermal conductivity and the phase change temperature of PCM. The increasing number of channels results in a decrease of the maximum temperature ( T Max ) and maximum temperature difference (Δ T ) of battery packs. The optimal phase change temperature and thermal conductivity of PCM were 308.15 K and 0.6 W m −1 K −1 respectively when the number of channel was eight and the mass flow rate was 8 × 10 −4 kg s −1 . Moreover, a maximum temperature of 320.6 K was predicted for the PCM/mini-channel coupled BTM system, while a maximum temperature of 335.4 K was predicted for the PCM-based BTM system. Additionally, the PCM/mini-channel coupled BTM system presented more effective thermal performance and the research will be a clear indicator for the design of the PCM/liquid coupled BTM system. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries (LIBs) are extremely sensitive to their temperature and therefore, require a battery thermal management system (BTMS). BTMS is commonly employed to prevent thermal runaway of the LIB pack by controlling their operating temperature. This review paper provides various cooling strategies, including active and passive approaches, utilized in BTMSs. Air-cooled, liquid-based, and PCM-cooled techniques are first reviewed. This article presents an assessment of the application of nanofluids and nano-phase change materials (nano-PCMs) in BTMSs to improve heat dissipation from the LIB pack. This work emphasizes the utilization of these materials to intensify their thermal conductivity and suggests further investigations on their application in BTMSs. • Lithium-ion batteries are extremely sensitive to their temperature. • BTMS is employed to prevent battery thermal runaway by controlling its temperature. • Providing various cooling strategies for BTMS: active and passive approaches. • Presenting an assessment of the application of nanofluids and nano-PCMs) in BTMSs. [ABSTRACT FROM AUTHOR]

The present study introduces a novel fin–Phase Change Material (PCM)–Expanded Graphite (EG) composite for better thermal management of a Panasonic NCR18650BD battery at discharge rates higher than its maximum discharge limit 2C. Fins and EG are augmented with PCM to enhance its effective thermal conductivity. Initially, the electrical and thermal behaviors of the battery are simulated for 0.5, 1, and 2C discharge rates using the Newman P2D model, and these are validated against in-house experiments. Following this, the heat generation profiles are estimated from the numerical model to mimic the battery with a heater in the experiments conducted to propose an effective thermal management system for 2, 3, and 4C discharge rates. Three heat sinks, one sans fins, and the other two with 130 and 260 fins, respectively, are considered to perform experiments. Phase Change Material (PCM) named Eicosane (Ei) with an addition of 0, 10, 20, 25, and 30% weight fractions of EG is filled in the heat sinks to study the effect of composite PCM on the thermal regulation of the battery. The heat sink having 260 fins filled with 70% Ei - 30% EG composite outperforms the other heat sinks considered in this study by recording lower temperatures to the extent of 17.5, 20.5, and 22.7 °C than a plain heat sink filled with 100% Eicosane for discharge rates 2, 3, and 4C, respectively. Furthermore, with the addition of 30% EG by volume, the maximum thermal performance of heat sink having 130 fins surpasses the heat sink having 260 fins filled with pure Eicosane by recording 1.3, 0.5, and 1.5 °C lower temperatures for discharge rates 2, 3, and 4C, respectively. In view of this, a possible engineering solution is to employ a simple heat sink, having fewer fins filled with PCM–EG composite instead of intricate heat sinks, having more fins filled only with the baseline PCM, to overcome the design difficulties and manufacturing costs. • Introduced fin–PCM–EG composite heat sink for thermal management of Li-ion batteries. • Newman P2D model is used to calculate the heat generation for 2, 3, and 4C rates. • Compared performance of different heat sinks for 2, 3, and 4C rates experimentally. • Heat sink with 260 fins and 70% Ei - 30% EG outperforms all other combinations. • Addition of EG helps to propose a less intricate and more efficient heat sink. [ABSTRACT FROM AUTHOR]

• A numerical analysis is performed for direct liquid cooling of lithium-ion batteries using different dielectric fluids. • Study and compared the thermal performance of three different dielectric fluids including mineral oil, deionised water, and one engineered fluid. • The temperature rise is limited to below 3 °C for 1c- discharge by using deionised water at all mass flow rates, where oil-based fluids are delivering better performance only at higher mass flow rates of 0.05 kg/s. • The mineral oil and engineered fluids deliver almost an equal thermal performance, however, the latter consumed 76.43% less power at a mass flow rate of 0.05 kg/s. Lithium-ion battery (LIB) cells are responsible for powering most electric vehicles. LIB is still a superior battery available in the market because of its high energy density, specific power, and long cycle life. However, LIB comes with the challenges like thermal management as it is highly sensitive to temperature. Amongst different cooling methods, direct liquid cooling, also known as immersion cooling, can deliver a high cooling rate mainly because of its complete contact with the heat source. The single-phase liquid immersion with dielectric fluids (DELC) offers safety and cooling performance with lower parasitic power consumption and space requirements. This research involves studying and comparing different DELC's for the direct cooling of lithium-ion batteries. A numerical analysis of the 4S1P arrangement of LIB cells with direct cooling is conducted with three different DELC's including deionised water, mineral oil, and an engineered fluid. The transient behaviour of the battery module for various mass flow rates of DELC and at 1C,2C,3C-discharge rates are examined. All DELC maintains an excellent temperature homogeneity within the individual cells and LIB cells. The DELC with higher specific heat and thermal conductivity is suitable for cooling the LIB cells during high discharge conditions. However, all the dielectric fluids studied here effectively limit the temperature rise below 5 °C at 2-C discharging operation when the mass flow rate is increased to 0.05 kg/s. This improvement in thermal performance comes at the expense of extra power consumption. Even though both DELC-2 and DELC -3 delivered almost similar temperature rise values of 6.1, 5.2 °C, respectively during 2C discharging operation, the latter consumed 76.43% less power at a mass flow rate of 0.05 kg/s. For this reason, engineered fluids with lower viscosity values can be preferred over mineral oils. The deionised water is more effective for limiting the temperature rise below 2.2 °C for 3C discharging with the least parasitic power consumption of 0.52 mW at a mass flow rate of 0.05 kg/s. A variable cyclic load matching HWFET-driving cycle has been applied to the battery pack with all three DELCs, and all three fluids limited temperature rise below 1 °C. [ABSTRACT FROM AUTHOR]

In this study, a novel thermally induced flexible phase change material (PCM), which consists of an elastomeric block copolymer called styrene-b-ethylene-co-butylene-b-styrene triblock copolymer (SEBS), paraffin (PA) and expanded graphite (EG), is successfully prepared. Here, SEBS and EG serve as a supporting material and a thermal enhanced component. The effects related to latent heat, thermal stability, thermal conductivity and shape stability of different SEBS mass fractions are investigated and the test results reveal the good thermal performance of the PA/SEBS/EG blends. Besides, the further rheological analysis points out that the property of shape stability and thermal induced flexibility are based on the physical crosslinking mechanism between SEBS and PA. As a result, PA/SEBS/EG composite considerably reduces thermal contact resistance due to narrower gap, endowing the battery module with much better heat dissipation efficiency and temperature uniformity. The 3 C discharge of the battery module test shows that the maximum temperature of battery module using PA/SEBS/EG blend is effectively controlled within 42.2 °C, while the maximum temperature difference is below the safety threshold of 5 °C during the 5-cycling discharge and charge tests. • A novel CPCM with thermally induced flexibility and shape stability is proposed. • Detailed analysis of the thermophysical properties has been conducted. • The thermally induced flexibility can obviously reduce thermal contact resistance. • Flexible CPCM exhibits excellent heat dissipation performance. [ABSTRACT FROM AUTHOR]