Battery Thermal Performance Research Articles

Experimental investigation on thermal performance of battery using composite phase change material

Experimental investigation on thermal performance of battery using composite phase change material

An air‐cooled cylindrical Li‐ion 5 × 5 battery module with a novel flow‐diverting arrangement and variable vent positions for electric vehicles: A numerical thermal analysis

AbstractThermal management of lithium‐ion batteries has received a lot of interest in the automobile sector. In commercial electric motor vehicles, an efficient battery cooling arrangement, particularly active cooling approaches, has been chosen as an ideal option. When building battery cooling systems, the physical structure and arrangement of the battery pack (BP) are vital. The current study presents a revolutionary design of a BP that incorporates cylindrical cells in a square duct and an air‐cooling (AC) medium circulated in its surroundings with the help of variable vents for inlet and outlet. A forced‐AC system is used to test lithium‐ion battery cells grouped in a 5 × 5 configured battery module. To investigate the impact of heat generation on battery thermal performance, a complete thermal analysis was performed at different discharge rates of 0.5, 1, 2, 3, and 4 C. As compared with both inlet vents at an equidistance configuration with an inlet velocity of 12 m/s and a flow rate of 1.210(−2) kg/s, the results show that the proposed design minimizes heat accumulation by enhancing the heat transfer. As a result, the peak temperature and temperature disparity decreased by 6.76% and 85.32%, respectively. A flow‐dispersing disc of 30 mm in size enhances temperature uniformity in comparison to the other intake vent design, hence improving battery safety and longevity.

Optimization of Lithium-ion battery thermal performance using dielectric fluid immersion cooling technique

Lithium-ion batteries (LIBs) are crucial for portable electronics, electric vehicles, and renewable energy systems. However, conventional cooling techniques for LIBs struggle to efficiently dissipate heat during rapid charging and discharging, potentially compromising performance and safety. This study explores the immersion cooling technique to optimize the thermal performance of 4S2P LIB module at 3 C discharge rate. The MSMD-NTGK battery model is utilized in numerical simulation to analyze the electrochemical and thermal characteristics of LIBs. Initially, static and forced convection immersion cooling methods are compared using two different cooling media: ester-oil and air. Static convection with ester oil reduces temperature rise by 8.3 % compared to natural air convection, while forced convection with ester oil achieves optimal temperatures (< 5 °C) at a fluid velocity of 0.077 m/s (20 LPM), lower than forced air convection. Furthermore, the study enhances forced convection with ester oil-based immersion cooling for LIB with different inlet and outlet structural designs. Among these, the middle inlet and middle outlet-center (MIMO-C) flow model demonstrates optimal temperature at reduced flow rate of 5 LPM and minimal pressure drop of 230 Pa compared to others. These findings underscore the potential of forced convection-based immersion cooling to improve LIB performance and lifespan.

Hierarchical thermal modeling and surrogate-model-based design optimization framework for cold plates used in battery thermal management systems

The continued advancement of battery-powered electric vehicles (EVs) towards higher energy and power densities poses significant thermal challenges for batteries. This work proposes a generalized design optimization framework for battery thermal management systems (BTMS), responding to the need for EVs with enhanced battery thermal performance, safety, and lifetime. This framework combines hierarchical thermal modeling and surrogate-model-based design optimization, explicitly tailored for liquid-cooled cold plates commonly used in EV BTMS. The hierarchical thermal modeling component decouples the battery cell, battery module, and cold plate models to reduce computational modeling costs while preserving the relative thermal performance of different cold plate designs. The design optimization component leverages our pioneer deep encoder–decoder hierarchical (DeepEDH) convolutional neural network surrogate modeling methodology to predict the cold plate’s full pressure, velocity, and temperature fields. Computationally efficient DeepEDH neural networks replace costly transient thermal simulations of cold plates and compute the objectives for evolutionary optimization using the Non-dominated Sorting Genetic Algorithm II (NSGA-II). This work’s novel modeling and optimization framework produces optimal cold plate designs that consider battery-module-specific design features, including distributed battery cell heat generation, packaging materials, and heat-spreading characteristics. The proposed framework is evaluated through a cold plate design for modular BTMS, thoroughly assessing the impact of optimization objectives, flow path constraints, modeling assumptions, and design variable choices. The results demonstrate the effectiveness of the combined hierarchical thermal modeling and design optimization framework, with the optimized cold plates achieving reductions of 6.26K, 6.29K (22.7%), and 16.16Pa (18.7%) for maximum temperature, maximum temperature difference, and pressure loss, respectively. Moreover, compared to other methodologies that apply direct optimization without hierarchical and surrogate models, our approach significantly reduces the computational cost — from approximately 4800h to 13.5h. Our generalized multi-objective optimization framework is an effective and efficient design tool that can be leveraged to advance thermal management innovations for next-generation battery systems.

Effects of the cold plate with airfoil fins on the cooling performance enhancement of the prismatic LiFePO4 battery pack

To maintain the optimal battery performance, it is essential to develop an efficient battery thermal management system for keeping the battery operation temperature within the appropriate range. In this work, a novel design of cold plate featuring airfoil fin channel is developed as a highly effective cooling module of a prismatic LiFePO4 battery pack. The thermal performance of battery and the thermo-hydraulic performance of the cooling module for the cold plate featuring airfoil fin channel, U-type channel and serpentine channel are numerically investigated and compared to reveal the superiority of the novel cold plate. The results indicate that compared with the U-type channel and the serpentine channel, the airfoil fin channel can enhance the total heat dissipation amount by 3.47% and 4.64%, respectively. Besides, the airfoil fin channel can provide the smallest battery maximum temperature and temperature difference under the same coolant flow rate. The airfoil fin channel provides the smallest pressure loss and heat transfer coefficient but the largest overall thermo-hydraulic performance indictor in terms of j/f factor. Under the same requirement of battery cooling performance, the remarkably smaller power consumption is required for the airfoil fin channel compared with the U-type channel and serpentine channel.

The Role of Current Collector Corrosion on the Performance of Thermal Batteries

As a bridge connecting external circuits and electrodes, current collectors are critical for battery performance. While numerous studies have investigated lithium-ion battery current collectors at room temperature, fewer address high-temperature batteries (&gt;500 °C). The interfacial properties of thermal battery collector and cathode at high temperatures remain unclear, and collector selection is more empirical. In this paper, the effects of 304 stainless steel on the discharge performance of NiS2 cathode were investigated. At 500 °C, 100 mA cm−2 and 1.5 V cutoff voltage, NiS2 first-voltage plateau specific capacity with 304 stainless steel current collector exhibits a high specific capacity of 320 mAh g−1 and total specific capacity of 700 mAh g−1, 146% and 17% higher than Ni, respectively. The Ni current collector of the thermal battery underwent severe chemical reactions at high operating temperatures, consuming active mass and increasing interfacial impedance. In contrast, stainless steel formed an iron-chromium sulfide passivation layer inhibiting further chemical reactions and accelerating charge transfer rate at the interface, resulting in effective increase in the discharge capacity of the thermal battery. This study provides theoretical guidance for selecting current collectors for thermal batteries based on high-temperature chemical reactions.

Use of modern algorithms for multi-parameter optimization and intelligent modelling of sustainable battery performance

The focus of this computational work is to predict and optimize the battery thermal performance indicators for its sustainable operation using different meta-heuristic optimization algorithms and machine learning models. The contribution of this work is two-fold, first, the heat removal ability from battery indicated by average Nusselt number (Nuavg) and hotspots (MaxT) to avoid battery thermal runaway are optimized as single objective optimization (SOO) and as multi-level objective optimization (MOO) problem. Second, intelligent algorithms: Gradient boosting (GB) algorithm and Gaussian process regressor (GPR) algorithm are used for modelling of Nuavg and MaxT. For SOO, Multi-verse optimization (MVO) and Grey wolf optimization (GWO) algorithms are used for individual battery performance indicators. Similarly, the enhanced version of MVO and GWO for MOO (MMVO and MGWO) algorithms is customized. Each algorithm is operated for five cycles and 100 iterations in each cycle of execution. In GB algorithm the effect of different loss functions and in GPR algorithm the effect of parameter alpha (α) is analyzed. SOO gives highest fitness of Nuavg and lowest hotspots occurrence from both the algorithms with same converged positions of operating parameters. MMVO and MGWO relatively provide lower Nuavg with MaxT in the same range of SOO. The MOO provides different set of particle positions compared to SOO. MGWO algorithm has outperformed in providing the best non-dominated solution. The GB and GPR algorithm are good enough for the forecasting of battery thermal parameters. GPR is even accurate, however the range of α is important during training and testing. The best Nuavg obtained from SOO using MVO algorithm is around 82.06 while MaxT is 0.34. The same from GWO algorithm is 82.05 and 0.33 respectively. MGWO algorithm in MOO provides Nuavg and MaxT around 75.57 and 0.34 while MMWO provides 66.76 and 0.33 respectively. GPR algorithm gives accuracy as close as 98 % for MaxT while it gives 94 % accuracy for Nuavg. On the other hand GB algorithm gives 99 % and 97.5 % accuracy for MaxT and Nuavg respectively.

Daily sorption thermal battery cycle for building applications

The study propose firstly an absorption thermal energy storage (ATES) system designed for repeated operations on a daily base without any additional manipulation. The performance of the sorption thermal battery was analyzed by varying four parameters (mass flow ratio, number of exchanger heat transfer units (NTU), heat source, and cooling water temperature). The lower the cooling water temperature, the better was the performance, particularly for improving the energy storage density (ESD). Additionally, if low-temperature cooling water is used, the coefficient of performance (COP) with a 65 °C heat source is comparable to that with 95 °C. ESD increased with the increasing the heat source temperature, and the maximum COP was obtained when using a 75–85 °C heat source. To solve the crystallization problem, [DMIM][DMP], a type of ionic liquid, was applied as an absorbent. However, the COP of H2O-[DMIM][DMP] with a heat source temperature of 120 °C was lower that of H2O–LiBr with 95–100 °C. Therefore, it is advantageous to use H2O–LiBr to improve the sorption thermal battery performance. ESD and COP of the sorption thermal battery are 451.13 kJ/kg and 0.728, respectively, when using a 95 °C heat source and 32 °C cooling water.

Proposing a Hybrid Thermal Management System Based on Phase Change Material/Metal Foam for Lithium-Ion Batteries

The charging and discharging process of batteries generates a significant amount of heat, which can adversely affect their lifespan and safety. This study aims to enhance the performance of a lithium-ion battery (LIB) pack with a high discharge rate (5C) by proposing a combined battery thermal management system (BTMS) consisting of improved phase change materials (paraffin/aluminum composite) and forced-air convection. Battery thermal performance is simulated using computational fluid dynamics (CFD) to study the effects of heat transfer and flow parameters. To evaluate the impact of essential parameters on the thermal performance of the battery module, temperature uniformity and maximum temperature in the cells are evaluated. For the proposed cooling system, an ambient temperature of 24.5 °C and the application of a 3 mm thick paraffin/aluminum composite showed the best cooling effect. In addition, a 2 m/s inlet velocity with 25 mm cell spacing provided the best cooling performance, thus reducing the maximum temperature. The paraffin can effectively manage thermal parameters maintaining battery temperature stability and uniformity. Simulation results demonstrated that the proposed cooling system combined with forced-air convection, paraffin, and metal foam effectively reduced the maximum temperature and temperature difference in the battery by 308 K and 2.0 K, respectively.

Heat discharge performance of metal hydride thermal battery under different heat transfer conditions: Experimental findings

Thermal batteries utilizing metal hydride pairs are gaining tremendous research appeal for their applications in thermochemical energy storage. The pair consisting of a high-temperature metal hydride (HTMH: Mg-based hydride) and a low-temperature metal hydride (LTMH: AB2 type hydride) is attractive due to its relatively high energy storage density and medium energy storage efficiency. The energy storage efficiency can be significantly increased by improving the heat discharging performance of the thermal battery. In this study, we experimentally explore the heat releasing performance of an MgH2/(TiZr)(MnFeCr)2-based thermal battery. More specifically, the effects of LTMH bed heat transfer conditions on the heat discharging performance were briefly discussed. These heat transfer conditions include natural convection, forced convection, and resistive heating. The results showed that when operating the LTMH bed under active heat transfer conditions (forced convection or resistive heating), the thermochemical energy storage density varies between 1500 and 1820 kJ/kg-Mg with relatively high-temperature lift (heat upgrade) between 47 and 55 °C. On the other side, the thermal battery discharges heat at a relatively high specific power, ca. 100–225 W/kg-Mg, which can be a benefit for heat-to-work conversion applications using organic or steam Rankine cycles.

A coupled model and thermo-electrical performance analysis for flat heat pipe-based battery thermal management system

Power battery is one of the key components of the electric vehicles, and an efficient battery thermal management system (BTMS) is significant for improving power battery performance. Flat heat pipe (FHP) has lightweight structure and high thermal conductivity, receiving much more focuses in the field of BTMS. In this paper, an FHP-based BTMS configuration is proposed. A coupled model of FHP and batteries was established considering the vapor flow effect of the FHP working medium, which can calculate the battery electrochemical parameters, battery heat generation rate, FHP heat transfer capacity in real time. The coupled model was verified by experiment. Then, the battery thermo-electrical performance at different discharging conditions is simulated and analyzed, and the relationship between battery electrochemical parameters and discharge rate is reflected. Under 3C discharge rate, the battery maximum temperature can be limited under 50 °C, while the maximum temperature difference can be kept below 2.26 °C. Finally, the influence mechanism of different FHP structural parameters including vapor chamber thickness, FHP total thickness, FHP total length on battery thermo-electrical characteristics is investigated. The results show that the decrease of FHP vapor cavity thickness or FHP total thickness will not only increase the vapor thermal resistance, but also aggravate the uneven distribution of FHP heat transfer capability, worsening the battery thermal performance on this occasion. The uneven battery module temperature distribution will further lead to non-uniformity of battery electrical performance. The change of FHP total length will result in the change of the total FHP heat transfer thermal resistance and affect the battery overall performance.

Thermal Management of Lithium-Ion Batteries Based on Honeycomb-Structured Liquid Cooling and Phase Change Materials

Batteries with high energy density are packed into compact groups to solve the range anxiety of new-energy vehicles, which brings greater workload and insecurity, risking thermal runaway in harsh conditions. To improve the battery thermal performance under high ambient temperature and discharge rate, a battery thermal management system (BTMS) based on honeycomb-structured liquid cooling and phase change materials (PCM) is innovatively proposed. In this paper, the thermal characteristics of INR18650/25P battery are studied theoretically and experimentally. Moreover, the influence of structure, material and operating parameters are studied based on verifying the simplified BTMS model. The results show that the counterflow, honeycomb structure of six cooling tubes and fins, 12% expanded graphite mass fraction and 25 mm battery spacing give a better battery thermal performance with high group efficiency. The maximum temperature and temperature difference in the battery in the optimal BTMS are 45.71 °C and 4.4 °C at the 40 °C environment/coolant, as against 30.4 °C and 4.97 °C at the 23.6 °C environment/coolant, respectively. Precooling the coolant can further reduce the maximum battery temperature in high temperature environments, and the precooling temperature difference within 5 °C could meet the uniformity requirements. Furthermore, this study can provide guidance for the design and optimization of BTMS under harsh conditions.

A novel passive polymer-sorbent thermal battery for low-temperature energy applications: A numerical feasibility study

Sorption thermal energy storage (STES) systems offer great potential for meeting the growing energy needs and increasing the use of renewable energy resources. However, the complexity and large-scale of current STES technologies lead to relatively low-efficiency systems, severely limiting their widespread implementation. To address this challenge, this study presents a novel and compact smart-polymer sorbent (SPS) thermal battery with passive material-enabled mechanisms for controlled low-temperature thermal energy storage applications. A numerical model is established to investigate the coupled heat and mass transport processes underlying the working behavior of the SPS battery. It is also used to reveal the interdependence of the two processes and the limiting factors for the battery's thermal performance. The heating performance of several SPS battery designs was studied as an example, focusing on their application for cold environment thermal protection. Moreover, the influence of various design parameters was examined, including sorbent selection, void fraction, relative humidity, gate thickness, and gate-to-sorbent area, along with their implications to the coupled mass-heat transport processes. The results revealed that diffusion-based mass transport is the limiting process affecting the SPS battery thermal performance. The numerical simulation results also indicated that the sorbent selection should consider their low recharge temperature (40 °C–100 °C) and less pronounced temperature-dependent adsorption behavior to maximize the heating performance of the SPS battery. In addition, the SPS battery heating efficiency could be enhanced by increasing the sorbent void fraction to 0.35, relative humidity (RH) to 40 %, and gate-to-sorbent area to 60 % while decreasing the gate thickness to 0.1 μm effectively, which facilitate the diffusion-controlled mass transport process. Lastly, a single layer SPS battery is beneficial for thermal regulation at low temperatures; however, using distributed battery designs had a significant thermal performance enhancement benefit of 90 % compared to the single layer design. Hence, our study reveals the complex coupling effects of the heat and mass transport processes within the proposed SPS battery and provides insights and guidance (e.g., materials selections and SPS design) for engineering emergent small-scale passive STES applications.

Thermal Propagation Modelling of Abnormal Heat Generation in Various Battery Cell Locations

With the increasing demand for energy capacity and power density in battery systems, the thermal safety of lithium-ion batteries has become a major challenge for the upcoming decade. The heat transfer during the battery thermal runaway provides insight into thermal propagation. A better understanding of the heat exchange process improves a safer design and enhances battery thermal management performance. This work proposes a three-dimensional thermal model for the battery pack simulation by applying an in-house model to study the internal battery thermal propagation effect under the computational fluid dynamics (CFD) simulation framework. The simulation results were validated with the experimental data. The detailed temperature distribution and heat transfer behaviour were simulated and analyzed. The thermal behaviour and cooling performance were compared by changing the abnormal heat generation locations inside the battery pack. The results indicated that various abnormal heat locations disperse heat to the surrounding coolant and other cells. According to the current battery pack setups, the maximum temperature of Row 2 cases can be increased by 2.93%, and the temperature difference was also increased. Overall, a new analytical approach has been demonstrated to investigate several stipulating battery thermal propagation scenarios for enhancing battery thermal performances.

Fast fabrication of high-quality electrolyte separators based on ceramic papers and its electrochemical performance in thermal batteries

• A route is proposed to load nanoparticles and electrolyte into ceramic paper separator. • The proposed route is efficient and safe, which can be promoted to used in large scales. • Electrochemical performance of thermal batteries can be obviously improved with ceramic paper as separator. Composites consisted of ceramic paper, nanoparticles as well as molten salt electrolyte, are developed as the new electrolyte separators to substitute the traditional ones in thermal batteries, due to their flexible manufacture and good exhibition in electrochemical performance. However, the existed methods for fabricating the composites by roughly dip-coating with aqueous solutions, are suffering from drawbacks such as inefficiency, low consistence, or high temperature risk. Therefore, a new approach based on a melting-absorption-diffusion process, by using precursors without solvent, is developed. Firstly, the salts are accurately weighted. Then they melt on surfaces of ceramic papers and diffuse inside. After being treated at appropriate temperature for hours, high quality electrolyte separators based on ceramic papers are achieved. Compared to the traditional approaches, the new method can obviously increase and accurately control the amount of loaded nanoparticles and molten salts for each time. The achieved electrolyte separators also exhibit good electrochemical performance in single cells of thermal batteries compared with the traditional ones. With advantages like easy operation, high efficiency, and improved performance, this melting and in situ loading method holds broad prospect in preparing electrolyte separators at large scale.

Method of liquid-cooled thermal control for a large-scale pouch lithium-ion battery

• Presents a method of liquid-cooled thermal control to a large-scale pouch battery. • Influence of fluid flowing on battery temperature field is investigated numerically. • Analyzes the glycol solution concentration on battery thermal distribution. • Studies the effect of cooling trigger-time on battery thermal performance. • Simulation effectiveness was authenticated by a constructed thermal test system. Excellent thermal management is very significant in preserving lithium-ion battery cell work-performance and extending cell cycle-life. This work presents a method of thermal control for a large-scale pouch cell by using an existing liquid cooling plate with streamline channels. Numerically, influences of mass flow rates, cooling trigger-time, and glycol solution concentration on the cell thermal distribution are analyzed in detail. Experimentally, the simulation effectiveness is validated by a constructed thermal test system. It is shown that the increasing mass flow rate plays a positive role in crippling the cell temperature rise and difference. However, there is a marginal effect in this condition. Effect of postponing cooling trigger-time on promoting the cell thermal homogeneity is negative, when the cooling starts at 31 °C, the final cell temperature and temperature difference beyond 32 °C and 5 °C, respectively. The maximum cell temperature and channel pressure drop increase with increasing glycol solution concentration from 0 to 80%. Experimental validation suggests that the test and simulation results coincide with each other (within 2.5 °C), indicating that a promising availability dwells in present thermal management to manage the cell temperature field under a desirable range. This study would be valuable for one to develop a reliable cooling solution for a battery pack stacked with large-scale pouch cells.

Numerical analysis and machine learning for battery thermal performance cooled with different fluids

A system of parallelly placed Li-ion batteries placed at different spacings and cooled by different coolants is analyzed. The prime focus is on the effect of spacings between the batteries on battery thermal performance. The temperature and heat flux at the coolant and battery interface is taken as continuous. Coolants used belong to thermal oils, gases, conventional oils, liquid metals, and nanofluids. Finite volume method-based numerical analysis is performed upon validation with experimental work reported in the literature, by developing a code in the C language. The simultaneous effect of battery aspect ratio, thermal conductivity, Reynolds number (Ref), and heat generation at different battery spacings for each coolant on average Nusselt number (NuH) is explored. An analytical model is developed and artificial neuro-fuzzy interference system (ANFIS) prediction of NuH is carried out later. Battery aspect ratio, thermal conductivity, and heat generation for any given coolant do not affect the NuH. However, the coolant Prandtl number at different battery spacings has a prominent effect on NuH. Thermal oils and liquid metal coolants show a significant and non-linear variation of NuH with increased battery spacings. The effect of Ref on NuH was linear as expected for all the coolants at different battery spacings. However, NuH variations for liquid metal at different Ref were highly non-linear. The mathematical model developed and ANFIS regression analysis indicated a very comfortable prediction of NuH. The R-squared value of the mathematical model is up to 0.98 while from ANFIS it is up to 0.985 showing a very good fitness of these models.

Heat Transfer Simulation and Analysis of Thermal Battery

This study aimed to establish thermal analysis conditions and techniques for thermal batteries used as special-purpose power sources through comparisons with experimental data. Grid independence was realized, and grids with an error rate of less than 1% were applied. For heat transfer analysis, an unsteady analysis was conducted from 0 to 1,000 s by using commercial software. To apply the experiment results of the housing surface temperature to the analysis, the convective heat transfer coefficient that represents an equivalent temperature tendency was obtained through thermal analysis; its value was 19.2 W/m2·K. Heat transfer analysis was conducted by applying this coefficient to a 2° full model. Through the analysis, the temperature distribution inside the thermal battery and its heat dissipation characteristics were investigated. For an operating time of 870 s, the total averaged electrolyte temperature, top and bottom electrolyte temperature, and middle electrolyte temperature were found to be 457 °C, 441 °C, and 466 °C, respectively. Assuming a minimum operating temperature of 450 °C for the electrolyte, the amount of power generated decreases sharply from the top and bottom electrolyte layers of the housing of the thermal battery. This is because rapid heat release occurs at the top and bottom of the housing compared to the sides. Therefore, improving the insulation performance of the top and bottom of the housing could significantly enhance the operational performance of the thermal battery; reinforcement of the side insulator would also be required. The obtained results could serve as significant basic data for improving the performance of thermal batteries and extending their operating time.

Study on the Influence of Flat Heat Pipe Structural Parameters in Battery Thermal Management System

Battery performance and lifespan are greatly dependent on its temperature, and a good battery thermal system (BTMS) can make the battery work at its favorable temperature range, improve its electrical performance, and extend its lifespan. Due to the high heat conductivity and large surface area of flat heat pipe (FHP), the FHP-based BTMS can quickly remove the heat produced by the battery and improve the temperature homogeneity among cells in the pack. In this study, the FHP is applied to the BTMS, and the influence of its structure on the battery thermal dynamics is studied. Firstly, a coupled thermal model for the FHP-based BTMS is established and verified by the experiment. This model integrates the resistance-based thermal model of the battery and FHP model based on the thermal resistance network. Then, the effect of the structure parameters of FHP such as the thickness, porosity, and particle diameter of sintered wick on the thermal performance of the battery is investigated. According to the results, the temperature variation among battery cells rises significantly when the dimensionless thickness of the wick is greater than 0.7. Moreover, the change of the porosity and particle diameter of the wick results in a nonlinear development of the wick thermal resistance which finally changes the heat conductivity of the FHP and battery temperature. Finally, a neural network model (NNM) is used to establish the relationship between the FHP parameters and battery thermal performance for optimizing the BTMS structure. According to optimization result, the optimized FHP can keep the maximum battery temperature below 40°C at a discharge rate of 2C and reduce the temperature variation in the battery by 7.4%.

Numerical investigation on thermal characteristics of a liquid-cooled lithium-ion battery pack with cylindrical cell casings and a square duct

The thermal management of Lithium-Ion batteries has gained significant attention in the automobile industry. An efficient battery cooling system particularly active cooling techniques have opted as a promising solution in commercial electric vehicles. The physical structure and configuration of the battery pack play a crucial role while designing the battery cooling systems. In the present article, a novel design of a battery pack is designed which includes the cylindrical casings to insert batteries into it and a liquid cooling medium is circulated in its surrounding. This acts as a midway solution between the direct and indirect liquid cooling techniques. The battery cooling system has been numerically modeled using a finite volume approach and theoretically investigated to analyze the thermal behavior of battery systems. The thermal performance of the twenty-five 18,650 Lithium-Ion battery cells arranged in a 5 × 5 configured battery module is evaluated using a forced-liquid cooling system. A detailed thermal analysis has been performed under different discharge rates of 0.5C, 1C, 2C, 3C, 4C, and 5C to determine the impact of heat generation on the battery thermal performance. The numerical model is validated with the empirical correlations of heat transfer for the accuracy of the proposed design. The results reveal that the proposed design minimizes heat accumulation by enhancing the exposure of the cell casings to the heat transfer medium. An even distribution of coolant to each cell provides uniform temperature distribution within the battery module. Further, the effect of natural convection has also been investigated and the results reveal that the maximum temperature rise has been reduced to a great extent at a convective heat transfer coefficient of 25 W/m2 K. Furthermore, an overall battery pack temperature below 28 °C is recorded at 0.5C and even at a higher discharge rate of 5C for 720 s, and the maximum temperature between adjacent cells is limited to 0.12 °C.