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• The cold plates of battery liquid cooling system are designed by topology optimization. • Consider the two cold plate models the inlet and outlet on the centerline or the diagonal. • Compare the numerical results of design cold plates with rectangular-channel and serpentine-channel cold plates. • Topology optimization cold plates have better cooling performance and lower flow resistance at the same inlet pressure. • The change of inlet pressure has an impact on the cooling effect of the cold plates. In this paper, the cold plates are designed to cool the rectangular lithium-ion battery packs by the topology optimization method. The topology optimization method obtains the channel structure in the two-dimensional model, and three-dimensional cold plate models are then established according to their two-dimensional structure. In a simple model for a battery pack, numerical analyses of topology optimization cold plate (TCP) are implemented using COMSOL software. Numerical results were compared with conventional rectangular-channel cold plate (RCP) and serpentine-channel cold plate (SCP) to investigate the cooling performance and flow characteristics of the cold plate. The results demonstrate that the flow channel structure of the cold plate has a significant influence on the temperature distribution of the battery. At 150 Pa inlet pressure, the maximum temperature of batteries with TCPs is reduced by 0.27% and 1.08% compared to that with RCP or SCP, and the temperature difference is lowered by 19.50% and 41.88%. Appropriately increasing the inlet pressure of the cold plate can also reduce the maximum temperature and temperature difference of batteries. Due to low flow resistance and high heat transfer coefficient, topology optimization will be widely used to design battery cold plates. [ABSTRACT FROM AUTHOR]

Majority existing organic composite phase change materials (CPCMs) are flammable that result in thermal hazards such as fire and explosions in battery modules. Furthermore, the performance of PCM-based battery modules in extreme conditions like thermal runaway has not been studied adequately. In this study, a tubular CPCM-cell structure is designed using physically flame-retardant-modified CPCMs, and a series of experiments on the CPCMs with/without real cells is conducted with calorimeter tests and SEM analysis on morphology structure. First, the calorimeter tests and comparison on the heat release rate (HRR) are conducted on the CPCMs with and without flame retardant additives. Results show that the addition of Al(OH) 3 reduced the HRR from 242.5 to 204.4 kW/m2 with 15 wt% additives. Besides, the analysis of the mitigating performances of structure-enhanced tubular module and traditional cuboid module with real batteries is conducted. A factor of safety (FOS) parameter is defined to evaluate the safety degree of thermal runaway domino with energy density. The FOS of blank, CPCM–0 C , and CPCM–15 C modules are 0, 3.59, and 16.67, respectively, while that of CPCM-15 T reaches 21.01, indicating a significant improvement on mitigating effects by structure enhancement compared to adding flame retardant additives. This study brings novelty in the design of PCM-based battery modules, particularly from the thermal safety prospect. • An optimized tubular module using modified CPCM is designed to reduce hazard risk. • Bottleneck issue is solved by structure enhancement without reducing energy density. • Effect of flame retardant additives on thermal hazards is tested with/without cells. • Mitigation of tubular unit with air-flow-channel on heat propagation is tested. • Evaluation of battery modules are conducted from two aspects simultaneously. [ABSTRACT FROM AUTHOR]

Serious performance loss of lithium-ion batteries at subzero temperatures is the major obstacle to promoting battery system in cold regions. This paper proposes a novel heating strategy to heat battery from extremely cold temperatures based on a battery-powered external heating structure. The strategy contains two stages: preheating process for battery cold-start, and temperature holding process for battery temperature control after preheating. The strategy switches from the preheating to the temperature holding according to the power capability of battery pack. Both the electrical and thermal behaviors of battery pack are described based on equivalent circuit models, and the state-of-charge and state-of-power of battery pack are co-estimated online to support the implementation of the strategy. Systematic battery-in-the-loop tests are conducted for a series-connected battery pack to verify the effectiveness of the strategy at – 40 °C. Experimental results show that the battery pack can not only be heated from −41.4 °C to −14.0 °C in 371 s by consuming 6.1% of nominal capacity without being over-discharged, but also output 64.81% and 66.59% of nominal energy for loading the modified dynamic stress test cycles and the modified federal urban driving schedule cycles respectively after preheating. [ABSTRACT FROM AUTHOR]

• TPC-et skeleton is introduced to realize the room-temperature-flexibility of FCPCM. • TPC-FCPCM shows great applicability to various kinds of cells and battery modules. • TPC-FCPCM shows outstanding cooling performance compared to classical rigid CPCM. • TPC-FCPCM is favorable to alleviating the compressive stress in actual application. Flexible composite phase change materials (CPCMs) can minimize the thermal contact resistance in battery thermal management. However, these "thermally-induced" flexible CPCMs only present well-flexibility above the phase change temperature, which is unfavorable to the flexible assembly of the cells and battery modules with variable specifications. Herein, a kind of flexible CPCM with well-retained flexibility in a wide temperature range is prepared by carefully selecting a copolyester thermoplastic elastomer with polyether soft segment (TPC-et) to replace the conventional olefin block copolymer (OBC) skeleton. The internal rotation resistance of the ether bond in TPC-et is much lower than that of the C–C bond in OBC, thus giving rise to a better flexibility in room and low temperatures from 20 to −5 ℃. Combining the room-temperature-flexibility with the high thermal conductivity of 1.64 W m−1 K−1, enough latent heat of 102 J g−1 and suitable phase change region of 40–50 ℃, the obtained TPC-et based flexible CPCM shows outstanding applicability and cooling performance to various cells and battery modules through facile installations. The maximum temperature of the cylindrical, prismatic and pouch battery modules with TPC-et based CPCM is 51.5, 42.1 and 50.0 ℃, respectively, 4.0, 3.9 and 5.4 ℃ lower than the modules using rigid CPCM, respectively. [ABSTRACT FROM AUTHOR]

Phase change materials, as smart, ideal latent heat storage, and passive technology, have become the promising option for thermal management. However, the melting leakage, poor mechanical property, and intrinsic low thermal conductivity are long-standing bottlenecks for practical applications. In this study, a synergetic method is proposed to fabricate phase change composites with excellent shape stability, flexible property, and high thermal conductivity. Here, paraffin is used as thermal energy storage material, styrene-ethylene-propylene-styrene served as supporting material provides a cross-linked network to restrict paraffin molecular and endow the composite with thermal-induced flexibility, and expanded graphite with lamellar structure constructs an interconnected thermally network. The thermal conductivities of composites reach up to 2.671–10.019 W m−1 K−1 with EG loading of 5–30 wt%. Simultaneously, the phase transition enthalpy is measured as high as 155.4–211.9 kJ kg−1, indicating that the composites have good thermal properties. In addition, the composites exhibit superior thermal management behavior by controlling the operating temperature of battery to below 50 °C under normal discharge-charge and dynamic stress test cycles. Therefore, this work offers a convenient and efficient method to synthesize scalable form-stable composite with promising performance for battery thermal management and other advanced thermal management applications. • A ternary form-stable composites is fabricated through blending and impregnation method. • Styrene-ethylene-propylene-styrene restricts the leakage of liquid paraffin and endow flexibility for composite. • The expanded graphite shows long-chain structure and constructs thermally conductive path in composite. • The resultant composites exhibit enhanced thermal conductivity in the range of 2.671–10.019 W m−1 K−1. • The thermal management performance of composite is evaluated under normal and dynamic battery experiments. [ABSTRACT FROM AUTHOR]

A novel heat transfer device for narrow space was proposed to meet high power battery heat dissipation. Based on the battery heat generation data, the heat transfer enhancement mechanism of the secondary flow pattern is studied. Then establish the general heat transfer correlation for this liquid-cooled structure with a specific aspect ratio. The results show that the channel with rib angle of 90° has higher Nu as well as ƒ and can achieve the same heat transfer performance with smaller flow rate. This is due to its transition flow pattern of twist-tape vortex and stagnant vortex, which can enhance the contact heat transfer performance of mainstream cold fluid while inhibiting the growth of boundary layer. The increase in rib number gradually decreases the gain of Nu with a minimum increment of less than 1%; while ƒ almost gradually increases with a common difference of 0.05. From the perspective of heat transfer and energy saving, increasing rib number does not essentially improve the heat transfer performance. Because the flow field at different rib number is just a mapping of the complete flow field at the corresponding length. Based on the above data, for the flat channel with aspect ratio of 10:3 in narrow space, the second-order general heat transfer correlation for different hydraulic diameter is established considering the Re , dynamic viscosity, rib angle and rib number. Finally, the coefficient of determination (R2) of the correlation is 0.9973, which can provide guidance for battery thermal management engineering applications. [ABSTRACT FROM AUTHOR]

• A battery thermal management system based on heat pipe-cooling is designed. • Multiple structure parameters of the aluminum sheet are investigated and optimized. • Impacts of factors on the cooling performance are analyzed by an orthogonal design. • Primary influential factors are obtained through fuzzy grey relational analysis. An efficient thermal management system is essential to maintain its good performance of a power battery pack. Evaluating the impacts of influential factors on the system cooling performance helps guide the design of the battery thermal management system. In the present work, a battery thermal management system based on heat pipes combined with a liquid-cooling plate is proposed. Orthogonal design and fuzzy grey relational analysis are employed as evaluating methods, and numerical simulations are carried out to investigate the influence of four structure parameters of the aluminum sheet (the height, the thickness, the covering angle to battery, and the covering angle to heat pipe) on the temperature distribution of the battery pack. Results show that, in order to keep a good operating temperature range of the battery, the values of the height, the thickness, the covering angle to battery and the covering angle to heat pipe of the aluminum sheet are suggested to be above 50 mm, 2 mm, 75° and 60°, respectively. The covering angle of aluminum sheet to battery has the most influential impact on the system cooling performance, and the covering angle to heat pipe has the slightest influence. The optimal value of the maximum temperature is 37.58 °C and the temperature difference is 3.67 °C. [ABSTRACT FROM AUTHOR]

• Design of a liquid cooling system for EV batteries based on the constructal law • Canopy-to-canopy architectures prove to have high thermal efficiency • They allow to maintain the battery cell below the critical temperature level With the growing interest on electric vehicles comes the question of the thermal management of their battery pack. In this work, we propose a thermally efficient solution consisting in inserting between the cells a liquid cooling system based on constructal canopy-to-canopy architectures. In such systems, the cooling fluid is driven from a trunk channel to perpendicular branches that make the tree canopy. An opposite tree collects the liquid in such a way that the two trees match canopy-to-canopy. The configuration of the cooling solution is predicted following the constructal methodology, leading to the choice of the hydraulic diameter ratios. We show that such configurations allow extracting most of the non-uniformly generated heat by the battery cell during the discharging phase, while using a small mass flow rate. [ABSTRACT FROM AUTHOR]

Thermal runaway severely affects the lithium batteries under conditions of non-normal forces or thermal abuse. In this study, a novel flame retardant flexible composite phase change material is successfully prepared, and a battery module based on it is designed and experimentally investigated. Herein, paraffin with high latent heat is performed as phase change material, Styrene-butadiene-styrene is employed as the supporting material, expanded graphite is used as the additive for thermal conductivity enhancement, and a flame retardant is utilized to suppress the heat diffusion and resistant flame. Experimental results reveal that a flame retardant flexible composite phase change material with 15 wt% flame retardant can achieve the optimum flame retardant effect, and its limiting oxygen index value can reach 35.9%. The battery thermal management with 15 wt% flame retardant composite phase change material can effectively avoid the heat accumulation of the battery module in the long cycle. In addition, thermal runaway trigger is simulated by heating rod at 200 °C, and the effect of the different composite phase change material modules on thermal runaway spread are compared. The result reveals that the flame retardant flexible composite phase change material could absorb and transfer the heat of the triggered battery timely and promptly, exhibiting a flame retardant effect necessary to avoid thermal runaway of the battery. [Display omitted] • A novel flame retardant flexible composite phase change material (CPCM) has proposed. • The battery modules with three different thermal management approaches are compared. • Flame retardant flexible CPCM based battery module exhibit an excellent cooling effect. • The thermal runaway (TR) propagation process has been divided into various stages. • The prevention of TR with flame retardant flexible CPCM is an effective method. [ABSTRACT FROM AUTHOR]

Abstract: Many portable devices such as soldier carrying devices are powered by low-weight but high-capacity lithium ion (Li-ion) batteries. An effective battery thermal management (BTM) system is required to keep the batteries operating within a desirable temperature range with minimal variations, and thus to guarantee their high efficiency, long lifetime and great safety. However, the rigorous constraints imposed by the budgets in weight and volume for this specific application eliminate the possible consideration of many existing classical cooling approaches and make the development of BTM system very challenging in this field. In this paper, a flexible hydrogel-based BTM system is developed to address this challenge. The proposed BTM system is based on cost-effective sodium polyacrylate and can be arbitrarily shaped and conveniently packed to accommodate any Li-ion stacks. This BTM system is tested through a series of high-intensity discharge and abnormal heat release processes, and its performance is compared with three classical BTM systems. The test results demonstrate that the proposed low-cost, space-saving, and contour-adaptable BTM system is a very economic and efficient approach in handling the thermal surge of Li-ion batteries. [Copyright &y& Elsevier]

Highlights: [•] Performances of a PCM-based battery thermal management system are investigated. [•] The PCM with the optimal thermo-physical properties is presented. [•] Numerical simulation is carried out and results fit with experimental data well. [Copyright &y& Elsevier]

Abstract: A novel distributed transient thermal model is proposed to investigate the thermal behavior of nickel–metal hydride (NiMH) batteries under fast-charging processes at constant currents. Based on the method of integral transformation, a series-form solution for the temperature field inside the battery core is obtained that takes account for orthotropic heat conduction, transient heat generation, and convective heat dissipation at surfaces of the battery. The accuracy of the developed theoretical model is confirmed through comparisons with numerical and experimental data for a sample 30 ampere-hour NiMH battery. The comparisons show that even the first term of the series solution fairly predicts the temperature field with the modest numerical cost. The thermal model is also employed to define an efficiency for charging processes. Our calculations confirm that the charging efficiency decreases as the charging current increases. [Copyright &y& Elsevier]

Abstract: A three-dimensional analytical model is proposed to investigate the thermal response of batteries, with a plurality of thin electrodes, to heat generation during their operation. The model is based on integral-transform technique that gives a closed-form solution for the fundamental problem of unsteady heat conduction in batteries with orthotropic thermal conductivities, where the heat generation is a function of both temperature and depth-of-discharge. The full-field solutions take the form of a rapidly converging triple infinite sum whose leading terms provide a very simple yet accurate approximation of the battery thermal behavior with modest numerical effort. The accuracy of the proposed model is tested through comparison with numerical simulations. The method is used to describe spatial and temporal temperature evolution in a sample pouch type lithium-ion polymer battery during galvanostatic discharge processes while subjected to convective–radiative cooling at its surfaces (the most practical case is considered, when surrounding medium is at a constant ambient temperature). In the simulations, emphasis is placed on the maintenance of the battery operational temperature below a critical temperature. Through definition of a surface-averaged Biot number, certain conditions are highlighted, under which a two-dimensional thermal analysis is applicable. [Copyright &y& Elsevier]

Abstract: This work studied the thermal management of lithium ion batteries both numerically and experimentally. Numerically, a two dimensional CFD (computational fluid dynamics) model has been developed to perform detailed simulations of the thermal management issues within a battery pack cooled by air. Experimentally, systematic tests were performed to provide datasets to validate the CFD model. The main components in the experimental facility included a multi-cell battery pack and a wind tunnel. The wind tunnel facility generated well-controlled cooling air flow with velocity up to 30 m s−1 (∼67 miles per hour). So that the study can be performed under flow conditions directly relevant to practice. The major contributions from this combined numerical-experimental study are threefold. First, the CFD model has been shown to capture the dynamics of the cooling of battery modules consisting of multiple battery cells, including temperature non-uniformity among cells. Second, the CFD simulations have been compared directly against experimental data to quantify the accuracy and validity of the CFD models. Third, based on the validated CFD models, a reduced-order model is developed to predict the maximum cell temperature in the battery module. The accuracy and simplicity of the reduced-order model makes it promising for in situ monitoring and control purposes. [Copyright &y& Elsevier]

• Low-temperature preparation of solid–solid phase change polymer (SSPCP) is realized. • One-step embedding technology of SSPCP into the battery module can be realized. • SSPCP shows excellent anti-leakage and heat-tolerance property at high temperature. • SSPCP presents outstanding temperature-control performance for battery modules. The high initiating temperature of polymerization up to 80–100 °C during the preparation of solid–solid phase change polymer (SSPCP) leads to the limitation of the embedding procedure during the construction of the battery modules. Herein, we develop a low-temperature preparation strategy for SSPCPs by introducing a redox initiation system to reduce the decomposition activation energy, thus realizing the procedure for embedding the SSPCP into a battery module. In addition to the intrinsic ~100% anti-leakage performance and ultrahigh heat tolerance up to 250 °C, the SSPCP/expanded graphite composite demonstrates a suitable phase change temperature of 47.8 °C, high thermal conductivity of 2.33 W m−1 K−1, and latent heat of 99.6 J g−1 for battery thermal management, thus delivering a lower maximum temperature (47.4 °C vs. 45.2 °C) for the battery module than traditional composite phase change material during 15 charge–discharge cycles. No leakage traces are detected in the SSPCP module. [ABSTRACT FROM AUTHOR]

The optimal performance of a Li-ion battery is directly impacted by temperature. In order to control the temperature rise and provide even temperature distributions in the battery pack, a thermal management scheme comprises thin heat sinks with multiple phase change materials (PCMs) and air channels is investigated in this paper. The cooling performance and temperature homogenization of the battery thermal management (BTM) system are carefully studied under various configurations of PCMs. The results show that increasing the air inlet velocity has less effect in suppressing the temperature rise at early discharge stage, but ameliorates as the discharge prolonged to 3600 s. The standard deviation of the temperature (STDV) and maximum temperature of the batteries can be decreased by arranging PCMs with a lower melting temperature at the midsection and a higher melting temperature at the air outlet region of the heat sinks. In addition, for volume fraction of PCMs, Case IV, having a PCM with a higher melting point adjacent to the air outlet region and occupying one-half the height of the heat sink, illustrates a lower temperature rise and decreases the maximum temperature in the battery module by 1.024 K, 2.186 K, and 2.553 K, compared to Case I, II, and III, respectively. • Multiple PCMs incorporated thin heat sinks for battery thermal management is proposed. • The thermal performance of the battery based on maximum temperature upsurge is investigated. • The distributions of PCMs based on melting point and latent heat were carefully explored. • The optimal design for the distribution of PCMs is obtained for the proposed battery. [ABSTRACT FROM AUTHOR]

l The critical thermal issues of lithium-ion batteries are introduced. l The design principles for batteries thermal management are presented. l The latest advances on battery thermal management systems are summarized. l Emerging technologies for next-generation power batteries are discussed. Replacing conventional gasoline-powered cars with electric vehicles (EVs) can reduce not only pollution emissions but also the dependence on fossil fuels. As the most widely used power source to propel EVs, lithium-ion batteries are highly sensitive to the operating temperatures, rendering battery thermal management indispensable to ensure their high performance, long cycle life and safe operation. In this review, we summarize the recent advances in thermal management for lithium-ion batteries. The critical thermal issues caused by high temperature, low temperature and temperature non-uniformity are firstly discussed. The design principles and the existing thermal management systems are then presented and elaborated extensively. Emerging technologies such as thermoelectric devices and internal heating methods for future battery thermal management are analyzed. We highlight that the combination of passive and active cooling/heating methods is promising to meet the stringent thermal requirements, particularly under dynamic conditions with drastic power fluctuations. Finally, the remaining challenges and perspectives of thermal management systems with high efficiency and durability are provided. This review offers comprehensive guidance on the design of advanced thermal management system for next-generation power batteries. [ABSTRACT FROM AUTHOR]

• Shark-skin bionic heat sink containing phase change material is developed. • The value of T max and ΔT of bionic heat sink are reduced by 5.49 K and 4.11 K. • The optimization method for the bionic structure height is proposed. • The ΔT of battery model is reduced to 1.22 K after the structure height optimized for seven times. • Environmental adaptability of the battery thermal management is studied. To improve the cooling efficiency and temperature consistency of battery module, a novel heat sink inspired by shark-skin microstructure is proposed to apply in battery thermal management system (BTMS), which is combined with axial air cooling and phase change material (PCM). The surface of the shark-skin bionic heat sink shows a number of regularly arranged and hollow raised structures. The cavities of these raised structures are filled with PCM. The effect of the structure parameters of shark-skin bionic structure on the cooling performance is investigated using validated computational fluid dynamic method. When the shape, height, length and interval of shark-skin bionic structure are triangular, 3 mm, 7 mm and 2.5 mm, respectively, the maximum temperature (T max) and temperature difference (ΔT) of battery module are control to 308.98 K and 3.21 K, while the consumption energy is 34.57 J. As compared with the normal case, the T max and ΔT of shark-skin bionic sink are reduced by 5.49 K and 4.11 K, respectively. Then, a method is proposed to optimize the height distribution of bionic structure. After the height distribution of bionic structure for battery module is optimized for seven times, its ΔT and energy consumption are reduced to 1.22 K and 26.81 J, while its T max is 309.19 K. Furthermore, the BTMS exhibits reliable cooling performance under different ambient temperatures and dynamic conditions. [ABSTRACT FROM AUTHOR]

• Dynamic battery thermal model integrated with vehicle dynamics is newly developed. • Transient traits of the electric motor and regenerative brake system are reflected. • Comparative analysis between two steady and dynamic operation modes are conducted. • The proposed model is highly applicable to any driving conditions and EV models. • The dynamic thermal effects are non-negligible large despite the cooling effects. Accurate thermal analysis of batteries for realistic operating conditions is a key requirement to develop an effective battery thermal management system of electric vehicles (EV), which ensures battery safety. In this context, a dynamic battery thermal model is developed to investigate the thermal characteristics of the battery module under dynamic EV operating conditions. The comprehensive modeling on EV dynamics is firstly conducted to determine the power demands with driving cycle applications. The efficiencies of components within the EV powertrain are closely considered, and the power consumed or regenerated in traction or brake mode is estimated. The battery thermal model considering both the joule and entropic heats is developed to predict the heat generation rates and temperature profiles following the dynamic battery loads. The developed models are validated within 3.98% for the EV dynamics model and 0.76% for the battery thermal model in relative error, respectively, allowing precise power and thermal simulation under the realistic operating conditions of the EV battery. A comparative analysis between the dynamic and steady modes for the same power loads to confirm the effects of the dynamic patterns is conducted for ten continuous cycles. As a result, the maximum differences between steady and dynamic modes are discovered about 3.57 times in heat generation, and 4.58 °C in temperature. These differences remain significant even with the thermal management, turning out more active cooling is required for normal operation under dynamic operating conditions. [ABSTRACT FROM AUTHOR]

It is important for the safety and good performance of a Li-ion battery module/pack to have an efficient thermal management system. In this paper, a battery thermal management system with a two-phase refrigerant circulated by a pump was developed. A battery module consisting of 240 18650-type Li-ion batteries was fabricated based on a finned-tube heat-exchanger structure. This structural design offers the potential to reduce the weight of the battery thermal management system. The cooling performance of the battery module was experimentally studied under different charge/discharge C-rates and with different refrigerant circulation pump operation frequencies. The results demonstrated the effectiveness of the cooling system. It was found that the refrigerant-based battery thermal management system could maintain the battery module maximum temperature under 38 °C and the temperature non-uniformity within 2.5 °C for the various operation conditions considered. The experimental results with 0.5 C charging and a US06 drive cycle showed that the thermal management system could reduce the maximum temperature difference in the battery module from an initial value of 4.5 °C to 2.6 °C, and from the initial 1.3 °C to 1.1 °C, respectively. In addition, the variable pump frequency mode was found to be effective at controlling the battery module, functioning at a desirable constant temperature and at the same time minimizing the pump work consumption. [ABSTRACT FROM AUTHOR]

As the temperature has a great effect on the cycle life and capacity of power battery on electric vehicles (EVs), a practical battery thermal management (BTM) strategy is required to adjust the battery temperature within an appropriate range and reduce the temperature inconsistency in the battery module. To achieve the multiple objectives, a nonlinear model predictive control (NMPC) method is proposed to optimize the cooling process of battery module. Firstly, a lumped thermal model of single lithium-ion battery under air cooling is presented, which considers the change of internal resistance with temperature and the change of heat transfer coefficient with coolant velocity. Considering the temperature inconsistency in the battery module, a thermal model of the battery module is derived based on the law of conservation of energy and verified. Due to the nonlinearity, time-varying parameters and multiple constraints of the thermal management system, the NMPC method is designed. Particle swarm optimization is used to solve the nonlinear programming problem in NMPC method. The simulation results show that the NMPC method ensures that the battery works near the target temperature under different working conditions, the deviation is less than 0.5 K, and the temperature inconsistency in the battery module is less than 1.2 K. In addition, compared with the PID method, the air flow consumption is effectively reduced. • A lumped thermal model considering inconsistency of battery module is established. • Nonlinear model predictive control is used for battery cooling and energy reduction. • Particle Swarm Optimization is used as NMPC solver to reduce the calculation burden. [ABSTRACT FROM AUTHOR]

The battery thermal management system (BTMS) is important to ensure the lithium-ion battery life, performance, and safety. A novel inclined U-shaped flat microheat pipe array (FMHPA) is used for BTMS to achieve high efficiency and space-saving in this study. The thermal control performance is experimentally studied and compared with the module without FMHPAs. Results show that the equivalent thermal conductivity of the inclined U-shaped FMHPA is approximately 4350 W m−1 K−1, and plays the role of core heat transfer element. The maximum temperature and temperature difference of the module with FMHPAs are reduced by 16% and 60%, respectively, compared with those of the module without FMHPAs; FMHPAs keep the module in a suitable temperature range for most of the time in the ambient temperature of 25 °C during the 1C charge–2C discharge cycle. Moreover, the temperature difference at cell and module level are maintained within 5 °C in ambient temperature of 25 °C and 40 °C. The heating rate of the module with FMHPAs reaches 0.61 °C/min under the temperature difference of less than 5 °C; variable power heating (from large to small) will increase the temperature rise rate of the battery by 0.19 °C/min. • Inclined U-shaped flat microheat pipe array is used in battery module. • The module with inclined U-shaped FMHPAs is compact in structure and saves space. • The separation of the coolant and batteries improves safety. • Module is kept in suitable temperature in 1C charge–2 C discharge cycle. • Temperature difference at cell and module level are maintained within 5 °C. [ABSTRACT FROM AUTHOR]

Battery Thermal Management System (BTMS) plays a significant role in determining the Electric vehicles (EVs) operating range and battery operating life cycle. Indeed, Phase Change Material (PCM) with outstanding characteristics like passive energy utilization to cool the battery, low cost, and effective operation seems to be an attractive option to be used for BTMS of EVs. However, opting for an exact PCM for the required application of the battery system depends completely on the thermal properties of PCM. Therefore, drawbacks and the advancement of PCM integrated BTMS compared to others should be scrutinized to have a comprehensive assessment on the PCM-integrated BTMS. The present review article majorly focuses on: i) - Advanced thermal properties of organic, inorganic, and eutectic PCM for integration with BTMS; ii) - Secondary assisted PCM cooling system for BTMS; iii) - Experimental development carried out with incorporation of composite PCM with BTMS; iv) - Economic comparative analysis on integrating PCM with EVs; v) - Critical analysis on environmental benefits of PCM based BTMS for EVs. In addition, the key outcomes of utilizing nanoparticle dispersed PCM into battery systems are highlighted. A separate section has been elaborated on the techniques used to overcome the drawbacks of thermal conductivity in PCMs. Finally, critical analysis and consolidation of experimentally hybridized and analyzed composite PCM for performance enhancement of batteries presented in the article would be a hot spot for future research work on EVs. [Display omitted] • Effects of PCM on battery thermal performance of EV are analyzed. • Nanoparticle dispersed PCM into battery systems are highlighted. • Nano-particles and metal fins structure is a viable option. • Economic and environmental benefits of PCM based EV are analyzed. [ABSTRACT FROM AUTHOR]

• Flow boiling of R1233zd(E) in a parallel channel heat sink was studied. • Transition of heat transfer pattern was verified with flow boiling visualization. • Local heat transfer data were compared with present correlations. • Simple modification was conducted to improve the prediction accuracy. Aiming for the application of refrigerant two-phase cooling on battery thermal management, this study presented an experimental investigation on the flow boiling characteristics of R1233zd(E) in a parallel mini-channel heat sink, which consisted of 21 channels with the length of 140 mm and the cross section of 1.5 × 1.5 mm2. Under the saturation pressure of 125 kPa, the boiling curve of R1233zd(E) and the heat transfer coefficient were analyzed under different heat fluxes (5-100 kW/m2), mass fluxes (150-600 kg/m2 s) and inlet subcoolings (2.5-8 K). In addition, the flow pattern was captured using high-speed camera. The results showed that the onset of nucleate boiling was delayed with the increase of refrigerant mass flux and inlet subcooling, while the transition of heat transfer was verified by flow pattern visualization. The measured wall superheat was compared with present correlations, showing that the predicted value was always smaller than the experimental results. Flow boiling on local points showed that the nucleate boiling was triggered later at the channel located at the center axis of the heat sink, meanwhile the approach of critical heat flux was more obvious at channel outlet. Due to the graduate transition of flow boiling mechanism, refrigerant mass flux had limited influence on the local heat transfer coefficient when the heat flux was lower than 30 kW/m2, while enhancement on heat transfer could be observed with larger mass flux when the heat flux exceeded 30 kW/m2. The local experimental data of heat transfer coefficient were compared with 6 correlations from the literatures. It was found that the best prediction was presented by Liu and Winterton model with a MAE of 23.4%, while Kim and Mudawar model showed best agreement under different mass fluxes. A simple modification was conducted on Kim and Mudawar model, and the calibrated model presented a better prediction accuracy with the MAE of 17.6% and 83.2% of total data within the error of ±30%. [ABSTRACT FROM AUTHOR]

• Liquid cooling of pouch type li-ion batteries with multi-stage Tesla valve proposed • Channel geometry, coolant properties optimized numerically from COMSOL simulation • Forward and reverse flow configuration across the multi-stage Tesla valve explored • An enhanced heat transfer in the reverse flow observed at the cost of pressure drop • Maximum cold plate temperature noted within 40°C for Re varying from 2500 to 4750 The operating temperature can significantly influence the performance, cycle life, and safety of Li-ion batteries used in electric vehicles. One of the critical factors is to assess the temperature distribution within the battery pack when operated under extreme conditions and choosing an appropriate cooling method. Concerning this, a liquid cooling plate comprising Tesla valve configuration with high recognition in microfluidic applications is proposed to provide a safer temperature range for pouch type Li-ion batteries. A multi-stage Tesla valve with forward and reverse flow configuration is designed and analysed to improve a conventional rectangular channel's intrinsic temperature gradient issues for turbulent flow conditions. Moreover, the influence of various parameters such as channel number, the distance between two consecutive valves, coolant temperature, and heat flux applied on the cold plate's top and bottom surfaces are numerically investigated for varying Reynold's number using COMSOL Multiphysics software. An enhancement in heat transfer with the reverse flow in multi-stage Tesla valve is seen, mainly caused by flow bifurcation and mixing mechanisms, at the cost of pressure drop. A cold plate with 4 channels and valve to valve distance of 8.82 mm exhibits the most effective cooling performance. [ABSTRACT FROM AUTHOR]

This paper presents a model-based cell-health-conscious thermal energy management method. An Arrhenius equation-based mathematical model is firstly identified to quantify the effect of temperature on the cell lifetime of a Nickel Metal Hydride (NiMH) battery pack. The cell aging datasets collected under multiple ambient temperatures are applied to extract the Arrhenius equation parameters. The model is then used as an assessment criterion and guidance for the thermal management design of battery packs. The feasibility and applicability of a pack structure with its cooling system, is then evaluated, and its design problems are studied by a computational fluid dynamics (CFD) analysis. The performance and eligibility of the design method is validated by both CFD simulations and experiments. [ABSTRACT FROM AUTHOR]

Abstract: The time-efficient yet accurate thermal modeling of the battery cells for electric and hybrid electric vehicles is essential improving the performance, safety, and lifetime of the battery system. This paper presents a spatial-resolution, lumped-capacitance (LC) thermal model for cylindrical battery cells under high Biot number (Bi⩾1) conditions where the classical LC thermal model is generally inapplicable because of a significant temperature variation in the cell volume. The spatial-resolution LC model was formulated using zero- and first-order Hermite integral approximations. For model validation, a one-dimensional, transient analytical (exact) solution using Green functions was obtained for a cylindrical Li-ion battery cell with uniform volumetric battery heat generation of Joule and entropic heating under convective cooling boundary conditions. It was found from the comparison of the results that the spatial-resolution LC thermal model can accurately and quickly predicts the cell temperatures (core, skin and area-averaged) under various dynamic battery duty cycles even for high Biot numbers due to highly convective conditions such as liquid cooling. [Copyright &y& Elsevier]

Abstract: Time-dependent, thermal behaviour of a lithium-ion (Li-ion) polymer cell has been modelled for electric vehicle (EV) drive cycles with a view to developing an effective battery thermal management system. The fully coupled, three-dimensional transient electro-thermal model has been implemented based on a finite volume method. To support the numerical study, a high energy density Li-ion polymer pouch cell was tested in a climatic chamber for electric load cycles consisting of various charge and discharge rates, and a good agreement was found between the model predictions and the experimental data. The cell-level thermal behaviour under stressful conditions such as high power draw and high ambient temperature was predicted with the model. A significant temperature increase was observed in the stressful condition, corresponding to a repeated acceleration and deceleration, indicating that an effective battery thermal management system would be required to maintain the optimal cell performance and also to achieve a full battery lifesapn. [Copyright &y& Elsevier]

Battery thermal management for high-power applications such as electrical/hybrid vehicles is crucial. Modeling is an indispensable tool to help engineers design better battery cooling systems. An accurate battery thermal model using a Foster network is proposed. The parameters in the Foster network, including capacitance and resistance, are extracted from computational fluid dynamics (CFD) results. The Foster network model is then shown to provide equivalent results as those from CFD under transient heat dissipation inputs. The model can be readily coupled with a battery electrical circuit model to form a complete battery system circuit model capable of predicting accurate battery temperature and the impact of temperature on battery electrical transient performance. [ABSTRACT FROM AUTHOR]

The large-format lithium-ion cells are growing in popularity as high-energy-density power sources in mobile applications, which calls for efficient and compact passive thermal management systems. Hydrogel, capable of absorbing and holding extremely large amounts of water, emerges as a new type of heat sink material. Herein, we presented a systematic study on the passive thermal management systems employing hydrogel for the 20 Ah large-format lithium-ion cell with emphasis on regulating the temperature homogeneity and temperature spike. Four types of configurations were designed and experimentally explored to achieve optimal cooling performance. It showed that introducing heat conducting plate between hydrogel and battery surface can effectively improve the temperature homogeneity, and the highest temperature and largest temperature difference were controlled to be only 40.5 °C and 2.5 °C even under a high discharge rate of 4C, which were about 2.5 °C and 2.3 °C lower than the pure hydrogel system. In addition, heat dissipation fins and copper foam were also employed to further accelerate the heat transfer process within the hydrogel. It showed that the fin-hydrogel system held the best performance and delivered a maximum surface temperature and a largest temperature difference of 32.6 °C and 1.4 °C over eight 3C/1C discharge/charge cycles. • Four hydrogel-based cooling architectures are explored for large-format batteries. • Temperature homogeneity is enhanced by the indirect-contact structure. • Fin-hydrogel system affords the best cooling performance. • Temperature spike and temperature gradient are well controlled even at 4C. • Sustainable cooling capability of the hydrogel systems is validated over cycles. [ABSTRACT FROM AUTHOR]

It is becoming increasingly apparent that wide application of electric vehicles (EVs) are subject to significant improvements in battery technology. Temperature sensitivity is a major issue adversely affecting battery performance and requiring a robust thermal control. Yet, this is challenged by the large variety of temporal scenarios though which heat is generated in a battery pack, demanding dynamic tools to predict the thermal evolution of batteries. Classical transfer functions provide a low-cost and effective predictive tool. However, they are limited to linear systems, while nonlinear predictive tools can become impractical for EV applications. Therefore, this study provides a methodology to assess the dynamics of battery cooling. This is achieved through conduction of high fidelity modelling of battery cooling exposed to different temporal disturbances on the internal heat generation. The results are then post-processed to evaluate the extent of linearity. A quantitative measure of non-linearity is further applied to clearly determine the degree of nonlinearity in the heat transfer response. It is shown that battery cooling system can be approximated as a linear dynamical system as long as the disturbances are of short duration and relatively low amplitude. Conversely, long and large amplitude temporal disturbances can render strongly nonlinear thermal responses. • A novel measure of nonlinearity of battery cooling process is introduced. • Cooling process remains nearly linear at low load modulation amplitudes (10%). • Long duration temporal disturbances of the battery load generate strong nonlinearity. • For linear conditions, transfer function of Nu is like a low-pass filter. [ABSTRACT FROM AUTHOR]

A battery thermal management system that effectively maintains its temperature is highly desired. However, the promising cooling method utilizing phase change materials (PCM) has challenges of low thermal conductivity and sharp temperature growth after complete melting. To address the problems, a hybrid system that couples PCM/copper foam with helical liquid channels is proposed and the effects of the influencing factors are investigated numerically. Results showed that the hybrid system achieved more than 30 K temperature drop than the natural convection case. The maximum temperatures with the helical pitch of 10 mm and 40 mm were 332.28 K and 332.88 K, respectively, compared to 334.17 K for the straight-channel system. The increments of helical diameter and tube number improved the battery temperature but raised the power consumption. The flow velocity growth could significantly reduce the battery temperature, but beyond 0.05 m/s the temperature became relatively stable. In the studied ranges, the temperature reached the optimum at the foam porosity of 0.92 and was reduced with the increasing pore density. The maximum temperature with the melting point of 28 °C was around 4 K and 8 K lower than that of PCM35HC and PCM44HC cases. The conclusions in this study could provide insights into the design of hybrid battery thermal management systems. • A hybrid battery thermal management system is studied. • Novel helical channels are employed. • Parameters from perspectives of the liquid channel, porous structure and PCM are investigated. • Nonequilibrium thermal model for the PCM/copper foam composite is used. [ABSTRACT FROM AUTHOR]

• A hybrid thermal management system with PCM, HP and liquid cooling is proposed. • A surrogate model is established based on Adaptive-Kriging-HDMR method. • Four sensitive factors are determined through global sensitivity analysis. • The optimized system is evaluated in the condition of cycling and thermal runaway. The hybrid thermal management scheme for lithium-ion battery combining the advantages of various thermal management strategies has been widely adopted. However, due to the complex influence parameters involved in the hybrid thermal management system, its optimal design has become a difficult problem. In this study, a hybrid thermal management system based on phase change material (PCM), liquid cooling, and heat pipe is first designed, and then a precise and reliable numerical heat transfer model is established. In order to optimize the system and improve the optimization efficiency, the Adaptive-Kriging-High dimensional model representation (HDMR) method is used to construct a surrogate model of the thermal management system, and the influencing factors sensitivity analysis and optimization design of the hybrid thermal management system are also conducted. The results show that the thermal conductivity of PCM, the thickness of PCM, the length of heat pipe and the velocity of inlet water have a significant influence on the maximum temperature and temperature difference of the battery system. According to the optimization design of these four factors based on the multi-objective particle swarm optimization (MOPSO), it is found that the optimized thermal management system has the best ability to dissipate heat and maintain temperature uniformity as compared to the original design. In addition, this optimization system has the ability to prevent thermal runaway propagation under the condition of thermal abuse conditions. With these prominent performances, the proposed method is expected to provide insights into the engineering design and optimization of the battery thermal management system for electric vehicle. [ABSTRACT FROM AUTHOR]

To improve the heat dissipation efficiency of batteries, the eutectic mass ratios of each component in the ternary low-melting phase change material (PCM), consisting of stearic acid (SA), palmitic acid (PA), and lauric acid (LA), was explored in this study. Subsequently, based on the principle of high thermal conductivity and low leakage, SA–PA–LA/expanded graphite (EG)/carbon fiber (CF) composite phase change material (CPCM) was prepared. A novel double-layer CPCM, with different melting points, was designed for the battery-temperature control test. Lastly, the thermal management performance of non-CPCM, single-layer CPCM, and double-layer CPCM was compared via multi-condition charge and discharge experiments. When the mass ratio of SA to PA is close to 8:2, better eutectic state is achieved, whereas the eutectic mass ratio of the components of SA–PA–LA in ternary PCM is 29.6:7.4:63. SA–PA–LA/EG/CF CPCM formed by physical adsorption has better mechanical properties, thermal stability, and faster heat storage and heat release rate than PCM. When the CF content in SA–PA–LA/EG/CF CPCM is 5%, and the mass ratio of SA–PA–LA to EG is 91:9, the resulting SA–PA–LA/EG/CF CPCM has lower leakage rate and better thermal conductivity. The temperature control effect of single-layer paraffin wax (PW)/EG/CF CPCM is evident when compared to the no-CPCM condition. However, the double-layer CPCM (PW/EG/CF and SA–PA–LA/EG/CF CPCM) can further reduce the temperature rise of the battery, effectively control the temperature and temperature difference, and primarily maintain the battery in a lower temperature range during usage. After adding an aluminum honeycomb to the double-layer CPCM, the double-layer CPCM exhibited better thermal conductivity and mechanical properties. Moreover, the structure showed better battery temperature control performance, while meeting the temperature control requirements during the charging and discharging cycles of the battery. [ABSTRACT FROM AUTHOR]

A heat pipe (HP) heat dissipation model of a lithium-ion-battery pack is established for the climate in the central and southern regions in China, and the heat transfer effects of various fins with different spacing and thickness are investigated. According to the change of heat dissipation, inlet and outlet pressure difference and average heat transfer coefficient with fin spacing and thickness, the relatively optimal heat dissipation fin structure parameters are determined, and the battery temperature distribution and temperature change under different discharge rates of the battery pack in a high temperature environment, and the characteristics of the HP heat dissipation battery thermal management system(BTMS) are analyzed and the effects of HP-based BTMS on battery startup heating in low temperature are evaluated. The results show that the optimal parameters are that the fin spacing is 5 mm, the thickness is 2 mm, the air flow velocity varies from 4 to 16 m/s, and the average heat transfer coefficient is 7.6–11.9 W/(m·K). The battery pack using the HP can reach the proper temperature of 288.15 K in 682s, 615s, and 375 s at 1C, 2C, and 4C discharge rates respectively. [Display omitted] • A heat pipe heat dissipation model of a twelve-lithium-ion-battery module is established. • Relatively optimal heat dissipation fin structure parameters are obtained. • Effect of HP-based BTMS on battery startup heating in low temperature is evaluated. [ABSTRACT FROM AUTHOR]

• Proximity effects of straight and wavy fins are examined in MHS for thermal management. • Various interruptions are proposed and tested for each case and the best model is found. • Fin interruption can decrease simultaneously both base temperature and pressure loss. • Enhancements up to 98.1% are found for interrupted models compared with integral models. Miniature heat sink (MHS) is a fluid-based cooling technique for battery thermal management. This paper takes a new look at the performance enhancement of MHS by combining different geometries of integral and interrupted straight and wavy fins. To this end, four general designs are considered as basic models: Case 1: straight-straight-straight (SSS), Case 2: wavy-wavy-wavy (WWW), Case 3: straight-wavy-straight (SWS), and Case 4: wavy-straight-wavy (WSW). Then, in order to achieve simultaneous reduction in pressure loss and base temperature, four different interruption arrangements are applied to proposed models as Class 1, Class 2, Class 3, and Class 4. Moreover, the synergy principle is applied to evaluate the thermal performance of proposed geometries. The results show that employing the wavy structure enhances the thermal performance. Among the basic models, WWW has the lowest base temperature and the highest occupied space. However, the interruption is more effective when it is performed on MHS with straight fins. All things considered, the interruption has higher effects on both thermal and hydrodynamic performances of SWS and WSW compared to SSS and WWW. Excluding WWW, the interruption can improve the overall performance of the studied cases. The considered performance index discloses that the best interruption class for the WWW, SWS, and WSW is identical. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper summarizes battery thermal modeling capabilities for: (1) an advanced vehicle simulator (ADVISOR); and (2) battery module and pack thermal design. The National Renewable Energy Laboratory’s (NREL’s) ADVISOR is developed in the Matlab/Simulink environment. There are several battery models in ADVISOR for various chemistry types. Each one of these models requires a thermal model to predict the temperature change that could affect battery performance parameters, such as resistance, capacity and state of charges. A lumped capacitance battery thermal model in the Matlab/Simulink environment was developed that included the ADVISOR battery performance models. For thermal evaluation and design of battery modules and packs, NREL has been using various computer aided engineering tools including commercial finite element analysis software. This paper will discuss the thermal ADVISOR battery model and its results, along with the results of finite element modeling that were presented at the workshop on “Development of Advanced Battery Engineering Models” in August 2001. [Copyright &y& Elsevier]

In this paper, the coupling system of liquid-cooled battery thermal management system (BTMS) and heat pump air conditioning system (HPACS) for battery electric vehicles (BEV) is designed and analyzed. The performances of liquid-cooled BTMS are concerned and analyzed from the perspective of air conditioning based experimental data. Besides, an automatic calibration model of the liquid-cooled BTMS based HPACS is established to predict cooling capacity and system coefficient of performance (COP) of the BTMS by support vector regression (SVR). To better obtain three hyper parameters (the penalty coefficient C , the RBF kernel function parameter γ , and the insensitive loss coefficient ε) of SVR model, particle swarm optimization (PSO) algorithm is introduced to optimize above three parameters. It is found that compared to SVR model, the correlation coefficient (R) of cooling capacity and system COP for the proposed PSO-SVR model in this paper is improved 2.1% and 2.8% respectively, the mean squared error (MSE) of and cooling capacity and system COP is reduced 87.8% and 82.9% respectively, which indicated that PSO-SVR model can be used as a new method to fit the complex nonlinear relationship among the system COP, cooling capacity and other influencing factors of the liquid-cooled BTMS based HPACS. • Comprehensive analysis from the perspective of air conditioning system. • Automatic calibration model for battery thermal management system. • The battery thermal performance estimation based on the SVR model. • SVR model with RBF kernel exhibits better generalization ability. [ABSTRACT FROM AUTHOR]

• A compound liquid cooling system for battery thermal management was developed. • Temperature rise of the cooling water affected the temperature uniformity. • Heating power, flowing rate, filling ratio and inclination were investigated. To develop an efficient and practicable liquid cooling system for battery thermal management, a compound liquid cooling system combining a grooved aluminum vapor chamber with a one-through flow cold plate was proposed and its thermal performance experimentally was studied. The heating power, coolant flow rate, filling ratio and tilting angle of the vapor chamber were investigated, which had an impact on the thermal resistance and temperature difference on the heating surface. The results showed that the vapor chamber with a 20%~30% filling ratio had the smallest thermal resistance and preferable temperature uniformity in horizontal configuration. Due to the heat and mass transport of phases along the longitudinal direction inside the vapor chamber, the temperature difference of the heating surface arising from the temperature rise of the coolant could be suppressed effectively. To evaluate the suppressed effect on the temperature difference of the heating surface, the suppression ratio was proposed. The suppression ratio on the heating surface rose with the increase in heating power and the decrease in flowing rate. The thermal resistance and temperature uniformity of the vapor chamber deteriorated in tilting configuration. The vapor chamber at a positive tilting angle configuration performed better compared with that at a negative tilting angle configuration. At 20%~30% filling ratio, the suppression ratio of the temperature difference on the heating surface could be achieved at 0.78 under positive tilting angle configuration. [ABSTRACT FROM AUTHOR]

• A boiling-cooling system is proposed for large-format pouch lithium-ion cells. • The system has good performance for single-discharge processes in static mode. • The flow mode enables the system a stable performance during cyclic operations. • The temperature gradient is abnormally enlarged by the fast flow of the coolant. • The intermittent flow mode delivers an impressive cooling performance. To manage the undesirable temperature spike and significant temperature gradient developed on the large-format lithium-ion cell, we propose and experimentally demonstrate a boiling-cooling thermal management system using NOVEC 7000 as coolant for a large-format 20-Ah LiFePO 4 lithium-ion cell. It shows that the boiling-cooling system delivers excellent capabilities in reducing maximum temperature and improving temperature uniformity under the static mode even for the 4C discharge process. To enable the boiling-cooling system a stable cooling performance during cyclic operations, the flow mode is explored. The maximum temperature is successfully controlled over cycles but a large temperature difference between regions near cell bottom and tabs is observed, especially at high flow rates. To resolve issues of the static and flow modes, the intermittent flow mode is finally conceived for the boiling-cooling system, with which the temperature spike and maximum temperature difference are controlled to be less than 36 °C and 2 °C at 2C operation. Such an impressive cooling performance, combined with the substantially low pumping work, suggests that efficient thermal management of large-format lithium-ion cells can be achieved by the boiling cooling system operated with an intermittent flow mode, which takes full advantage of the large latent heat absorbed and the high heat transfer coefficient during the boiling process. [ABSTRACT FROM AUTHOR]

Air-cooled battery thermal management system (BTMS) is universally adopted in electric vehicles for temperature control of battery packs. In the present study, we develop an efficient transient model for accurately predicting the battery cell temperature in different types of parallel air-cooled BTMSs. A flow resistance network model for BTMS with I-type flow is established according to law of momentum conservation. Based on energy equations, a transient heat transfer model is derived to calculate the temperature distribution of battery pack in the BTMSs. The model results are in good agreement with experimental data, verifying the effectiveness and efficiency of this model. The deviations of T max and Δ T max between the models and experiment are less than 1.5 K. Furthermore, by using the developed transient models, the deviations of T max and Δ T max respectively decrease by 70% and 26%, in comparison with previous study. Finally, based on the developed models, the widths of parallel channels and divergence/convergence ducts in the BTMSs are designed, leading to remarkably enhanced cooling performance. The present study provides an efficient transient heat transfer model for parallel cooling systems, which can provide a deeper insight into the system performance and be applied to structural optimization of the systems. • A flow resistance network model for BTMS with I-type flow is developed.. • A transient heat transfer model for parallel BTMSs is derived mathematically. • Experiments are conducted to verify the developed transient heat transfer model. • The optimized BTMSs based on the developed models achieve good performance. [ABSTRACT FROM AUTHOR]

• The heat generation and transfer modeling approaches of LIB are introduced. • The advantages and disadvantages on various multi-physical BTMS are summarized. • The emerging techniques in emergency battery thermal barrier are examined. • A novel BTMS framework is proposed based on CHAIN. New energy vehicles have significant prospects in reducing greenhouse gas emission and environmental pollution. Lithium-ion batteries are the favored power source in electric vehicles because of their high energy density and long service life. The battery performance depends noticeably on the temperature. Battery thermal management system, which can keep the battery pack working in a proper temperature range, not only affects significantly the battery pack system performance but is also vital for the safety and stability. This article mainly summarizes the thermal management models in the literature which can predict heat generation, heat transfer and the temperature distribution within the battery cell, module and pack. The multi-physical battery thermal management systems are divided into three categories based on different methods of cooling the phase change materials such as air-cooled system, liquid-cooled system, and heat-pipe-cooled system. The emergency battery thermal battier methods are also summarized in multi-scale included material scale, battery management system and supplementary system. Finally, we propose a novel digital solution for full-lifespan thermal management control of EV power system based on CHAIN framework that helps improve the power battery temperature control strategy applying multiple working conditions. Image, graphical abstract [ABSTRACT FROM AUTHOR]

• A novel liquid cooling plate embedded with PCM for battery thermal management. • The cooling plate provides a modular solution for battery cooling with PCM. • The cooling plate is 36% lighter than an aluminum cooling plate of the same size. • Up to 30% reduction in pump energy consumption is achieved by the new cooling plate. • The cooling plate provides a heating solution for batteries in cold temperatures. In this paper, an innovative liquid cooling plate (LCP) embedded with phase change material (PCM) is designed for electric vehicle (EV) battery thermal management. The proposed cooling plate is named "hybrid cooling plate" as it takes advantage of both active (liquid) and passive (PCM) cooling methods. The hybrid LCP is 36% lighter than a volumetrically equivalent traditional aluminum LCP, and in addition to the cooling capability, it provides a heating solution to slow the temperature loss of the batteries during the cold stop. The thermal behavior of the hybrid LCP for two different scenarios including the cooling performance under a real driving cycle, and the cold stop temperature performance are investigated and compared with a traditional aluminum LCP using a computational fluid dynamics (CFD) model. An experimental test bench is developed to test a prototype of the hybrid LCP and verify the CFD model. The cooling performance results indicate that the use of hybrid LCP could reduce the energy consumption of the pump required for circulating the coolant up to 30% in comparison with an aluminum LCP. Moreover, the novel designed LCP improves the temperature uniformity effectively. It was also found that the hybrid LCP could significantly delay the temperature drop at the cold stop situation of the EV and therefore, reduce the energy needed for the active heating of the batteries after short-term parking. These imply that the hybrid liquid cooling plate concept could be a promising thermal management solution for EVs. [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride and silicone rubber (h-BN/SR) composites were prepared by the mechanical stirring method, and their crystal morphology, chemical structure, thermal properties, and compression stress–strain performance were investigated. The experimental results suggest that silicone rubber combined with h-BN exhibits better thermal conductivity and mechanical properties. When the proportion of h-BN is 30 wt%, the thermal conductivity of the h-BN/SR composite material is 0.58 W/m∙K, which is 3.4 times that of pure silicone rubber. At the same time, the compressive strength of h-BN/SR is 4.27 MPa, which is 6.7 times that of pure silicone rubber. Furthermore, the finite element model was employed to numerically analyze the thermal behavior of a battery with a h-BN/SR composite as the thermal interface material. The analytical results show that the highest temperature of the battery decreased when using h-BN/SR as the thermal interface material in the battery thermal management system. The h-BN/SR composite can thus effectively improve the safety properties of batteries. [ABSTRACT FROM AUTHOR]

• Fins formed a multi-channel thermal conduction network in the PCM • The optimized fin intensified PCM system increased the working time by 121.9% • The proposed system could work efficiently in high-temperature environments The low thermal conductivity of phase change materials (PCM) dramatically hinders the PCM-based battery thermal management systems (BTMSs). In this work, metal fin intensified PCM systems were proposed for thermal control of Li-ion battery modules. Single-cell experiments were firstly performed to validate the model. The influences of the thermal management systems, distribution of fins, length of fins, and ambient temperature on the thermal behaviors of the battery modules were then numerically investigated by ANSYS Fluent. The results indicated that metal fins increased the heat exchange area and formed a multi-channel high thermal conduction network, which could intensify the heat dissipation rate and increase the working time by 98.4% compared with the PCM system. Modification of the distribution of fins resulted in more uniform thermal conduction networks and improved the working time by up to 15.2%. Extending the fins helped to expand the network. The working time was further enhanced by 8.3% by increasing the length of fins from 7.5 to 13.5 mm. Besides, the proposed fin intensified systems could work efficiently, even under high-temperature conditions. The corresponding working time was increased by 1.48, 1.49, and 1.81 times for the ambient temperature of 20, 30, and 40 ℃, respectively, compared to the PCM system, demonstrating the superiorities of the fin intensified PCM systems over the PCM systems. [ABSTRACT FROM AUTHOR]

The degraded performance of lithium-ion batteries at low temperatures is a key obstacle to the development of battery energy storage system applied in extremely cold environment. Therefore, this paper proposes a heating method based on model prediction to support the low-temperature operation of battery pack without additional power sources. Battery pack model is developed based on Thevenin equivalent circuit model. A co-estimator is established to update model parameters and state-of-charge online using adaptive recursive least squares and extended Kalman filter. The permissible discharging current of pack is predicted based on multiple constraints to prevent over-discharge. Then, the battery-powered heating structure, control circuit, and heating strategy are designed. The strategy contains a preheating process for cold-start and a holding process for stabilizing cell temperature. The method is verified experimentally through systematic battery-in-the-loop tests at the environmental temperature of – 40 °C. Results show that the method can uniformly preheat all in-pack cells from − 40 °C to − 20 °C in 330 s consuming 4.7% of nominal capacity. In holding process, it is energy-efficient to raise cell temperature continuously and then maintain at 5 °C, which makes 68.3% of nominal capacity available when loading a modified federal urban driving schedule. • Propose a battery-powered heating method for the battery pack working at – 40 °C. • Utilize the limited battery power to heat battery pack efficiently. • Develop model-based estimation and prediction to evaluate battery power capability. • Design the heating structure, control circuit, and strategy for heating control. • Conduct battery-in-the-loop tests for experimental verification and investigation. [ABSTRACT FROM AUTHOR]

• A hybrid cooling system is proposed for lithium-ion battery pack in EVs. • Cooling effect and energy consumption of the hybrid system are tested. • Hybrid system reduces Tmax to 29.6 °C and ΔT to 1.6 °C in dynamic working condition. • Desired thermal performance is achieved with a 62% reduction in energy consumption. Lithium-ion batteries have been widely used to propel electric vehicles (EVs) owing to their high energy density, long lifespan, and high stability. However, the inevitable battery heat generation, particularly when there is a rapid increase in power under dynamic working conditions, threatens the safety and performance of EVs. In this study, we develop a hybrid battery thermal management system incorporating micro heat pipe arrays, convective air, and intermittent spray water. The heat pipes siphon the heat from the inside of the battery pack to the outside, and convective air dissipates heat during the normal operation of the EVs, while further cooling is achieved via intermittent spray water at high-power operations. For a 75 Ah lithium-ion battery pack under dynamic working conditions, the proposed hybrid system enables the maximum temperature to be reduced to 29.6°C and the temperature non-uniformity to be 1.6°C, which are 21% and 57% lower than those of thermal management systems without water spraying functions, respectively. Additionally, the energy consumption of the hybrid thermal management system is 4.9 Wh, only accounting for 1.8% of the total battery pack power capacity. Given these advantages, it is expected that the proposed thermal management system is a promising tool to address the practical thermal problems of lithium-ion battery packs used in EVs. [ABSTRACT FROM AUTHOR]

• A novel cooling scheme by nano emulsion and ultrathin cold plate was presented. • Nano emulsion with no subcooling and particle size of 335–360 nm was prepared. • Lower T max and ΔT were obtained cooled by nano emulsion than cooled by water. • Lower Pumping power than water of nano emulsion was obtained. • The T max and ΔT were below 50 °C and 4 °C in discharge of 9C. This paper presents a 4 mm ultrathin mini-channel cooling system based on a nano phase change material emulsion (NPCME) for prismatic Li-ion batteries under high-rate discharge. The NPCME has a larger specific heat capacity than water and no subcooling. Experiments were conducted to compare the cooling performance of water versus NPCME. The results indicate that NPCME can obtain a better cooling effect than water if the inlet temperature is below and near the melting point. At the discharge of 9C, the temperature and temperature difference of the battery pack cooled by 10 wt% NPCME-OP44E were 46 °C and 3.5 °C, compared with 49.5 °C and 4.8 °C under water cooling. Beyond that, the NPCME was able to reach the same cooling performance as water using lower pumping power. The pumping power of the 10 wt% NPCME-OP44E cooling system was only 18.5% that of the water cooling system when the cooling target for the battery temperature difference was 3.5 °C. With regard to charge-discharge duties, the 10 wt% NPCME-OP44E cooling system could limit T max and ΔT max to 45.5 °C and 4 °C throughout all four cycles. [ABSTRACT FROM AUTHOR]

To improve the problems of large interface thermal resistance and low heat dissipation efficiency in battery thermal management (BTM), this paper uses methyl silicone oil as the matrix, AIN, copper powder (CP), and carbon fiber (CF) as thermally conductive fillers, and acetone and stearic acid as particle surface modification components. A variety of binary thermal silicone greases (TSGs) with different compositions were prepared. Different instruments were used to test the material properties of TSGs, and a better TSG was selected to coat the interface between battery and phase change material (PCM) for battery charging and discharging experiments. Through the analysis of experimental data, it was found that among the TSGs made of three mixed fillers (AIN/CP, AIN/CF, CP/CF), the three TSGs had good thermal stability, and their thermal degradation temperature both exceeded 300 °C. As the ratio of thermally conductive filler was gradually changed from 5:1 to 1:5, the TSG containing CP/CF had higher thermal conductivity and lower volume resistivity, while the TSG containing AIN/CF had the least damage due to interface wear. The acidification treatment of thermally conductive filler can improve the adsorption and compatibility of thermally conductive particles and silicone oil, and reduce the oil separation rate of TSGs. The prepared expanded graphite (EG)/paraffin wax (PW) composite phase change material (CPCM) has a relatively large latent heat of phase change, which can effectively control the temperature of the battery, but coating TSG between the battery and the CPCM can further enhance the heat dissipation effect of the battery. [ABSTRACT FROM AUTHOR]

• The novel radiator with bionic surface structure is proposed and applied to battery module cooled by an axial air-cooled BTM system. • The cooling performance of the battery module is enhanced when the inlet velocity of air increases, but the power consumption increases obviously. • The novel radiator thickness and the bionic surface structure height can effectively reduce the maximum temperature and the temperature difference of battery module. • When the optimal parameters of the bionic surface structure are used, the air cooling effect of the battery is the best. In order to enhance the cooling performance of air, a new type of radiator with bionic surface structure is proposed and applied to a cylindrical lithium-ion power battery pack with axial air cooling in this paper. The computational fluid dynamics (CFD) model of the battery module is established to study the effect of the inlet velocity and structure parameter of radiator with bionic surface structure on the cooling performance. It is found that when inlet velocity is higher than 0.8 m.s−1, the maximum temperature and the temperature difference of the battery module can be maintained within 308 K and 5 K during the 3 C discharge rate, respectively. Then, four structure parameters (thickness, shape, height, and length) of the radiator with bionic surface structure are optimized by the single factor analysis and the orthogonal test to enhance cooling performance and reduce power consumption. The results show that the thickness of plate is the most important parameter influencing the cooling performance and power consumption. Then, the height of bionic surface structure is the secondary parameter, and the shape of bionic surface structure is the parameter with a minimal impact on the BTMS. The best cooling performance can be obtained when the four structure parameters are 0.4 mm, trapezoid, 1 mm, and 61 mm, respectively. As compared with the original radiator, the temperature difference and power consumption of the optimized battery module are reduced by 8.1 % and 15.54 %, respectively, while the maximum temperature varies a little. The optimal case in this research can be widely applied to enhance the cooling performance in air-cooled BTMS. [ABSTRACT FROM AUTHOR]