Battery Heat Research Articles

A Reconfigurable Bidirectional DC–DC Converter With Integrated Battery Heating for Electric Vehicle Applications

A Reconfigurable Bidirectional DC–DC Converter With Integrated Battery Heating for Electric Vehicle Applications

Battery thermal safety management with form-stable and flame-retardant phase change materials

Phase change materials (PCMs), characterized by zero energy consumption and high energy storage density capability, have a wide range of applications. However, the development of organic PCM is restricted by their low thermal conductivity, easy leakage and high combustibility. In this study, we produced a composite phase change materials (CPCM) with both high thermal conductivity and flame-retardant effect for application in battery thermal safety management. We demonstrated that addition of a porous network structure of EG as a shaping support to increase PA's thermal conductivity, and incorporation of environmentally safe and non-toxic silica-based flame retardant (SiO2 sol) improved the flame retardant properties. The optimum mass ratio of the CPCM was obtained by comprehensive analysis of the shape and thermal stability, energy storage performance and thermal conductivity. It was also verified by cone calorimetry that the CPCM outperformed pure PA in several aspects: heat release, smoke release rate and emission of toxic gases. The cooling and thermal runaway experiment of the battery module showed that the addition of CPCM had a positive effect on absorption of battery heat and extending the time between the thermal runaway spread of battery modules (21 s increasing to 396 s), providing valuable time for the safe evacuation of people in the event of a runaway fire.

Investigating the Effect of Different Bidirectional Pulsed Current Parameters on the Heat Generation of Lithium-Ion Battery at Low Temperatures

Bidirectional pulsed current (BPC) heating has proven to be an effective method for internal heating. However, current research has primarily focused on the impact of symmetrical BPC on battery heat generation, while neglecting the influence of different BPC parameters. To address this gap, this paper investigates the effects of various BPC parameters on battery heat generation. Initially, an electro-thermal coupled model of the battery is constructed based on the results of electrochemical impedance spectroscopy (EIS) tests conducted at different temperatures and amplitudes at 20% state of charge (SOC). The validation results of the model demonstrate that the absolute errors of voltage and temperature are generally less than 50 mV and 1.2 °C. Subsequently, the influence of BPC parameters on battery heat generation is examined under different terminal voltage constraints, temperatures, and frequencies. The findings at 20% SOC reveal that symmetrical BPC does not consistently correspond to the maximum heating power. The proportion of charge time and discharge time in one cycle, corresponding to the maximum heating power, varies depending on the charge and discharge cut-off voltages. Moreover, these variations differ across frequencies and temperatures. When the terminal voltage is constrained between 3 V and 4.2 V, the maximum heat power corresponds to a discharge time share of 0.55 in one cycle. In conclusion, the results underscore the complex relationship between BPC parameters and battery heat generation, which can further enhance our understanding of effective heating strategies for batteries.

Development of Energy-Saving Battery Pre-Cooling System for Electric Vehicles

The performance, lifetime, and safety of electric vehicle batteries are strongly dependent on their temperature. Consequently, effective and energy-saving battery cooling systems are required. This study proposes a secondary-loop liquid pre-cooling system which extracts heat energy from the battery and uses a fin-and-tube heat exchanger to dissipate this energy to the ambient surroundings. The liquid then passes through a chiller to complete the cooling loop. The air-conditioning system is also used to cool the battery only if the temperature of the cooling water exceeds the maximum permissible temperature. The cooling load of the air-conditioning system is thus greatly reduced. The feasibility of the proposed cooling system is demonstrated experimentally under four simulated seasonal environmental conditions, namely high summer (35 °C), mean summer (30 °C), spring and fall (20 °C), and winter (7 °C). The results show that the pre-cooling system can dissipate 1000 W of battery heat in high summer, 2000 W in low summer, 3167 W in spring and fall, and more than 4000 W in winter. In other words, the pre-cooling system greatly reduces the cooling load of the air-conditioning system, and hence significantly reduces its energy consumption.

Analysis of lithium-ion indirect liquid cooling battery thermal management system with high discharge rate

<span lang="EN-US">Electric vehicles are developing rapidly and require technological support. Electric vehicles require good power storage. One of the reasonable parameters of a battery pack is its high discharge capability. A high discharge rate requires suitable cell and heat management capabilities in the battery pack. When discharging, it produces heat energy and needs to be released. The battery thermal management system (BTMS) is a method used to maintain battery heat. BTMS using liquid has a better performance compared to phase-change memory (PCM) and air cooling. The use of liquid coolers still has limitations. Namely, the weight of the cooling system is quite large because of a large amount of liquid which increases the weight of the battery. This study offers the potential to use mini channels mounted on cooling plates for application as BTMS. This research used the finite element method (FEM) process by simulating the process of fluid flow that occurs when the battery is used at various C rates. The results of this study indicate that the type of BTMS can keep the battery hot at working temperatures below 40 ºC.</span>

Investigating the use cases of a novel heat battery in Dutch residential buildings

AbstractRecent advances in thermochemical storage technology have introduced a novel closed-loop thermal energy storage (TES) system, known as the heat battery (HB), which is believed to have great potential for aiding the energy transition in the built environment because of its higher energy density and neglectable storage loss compared to conventional TES systems. In order to investigate the potential use cases of the HB and provide practical feedback for its further development, this research employs a simulation-based approach to analyze its influence on building performance in various use cases within Dutch residential buildings. Stakeholders including the homeowner, distribution system operator, and district heating system operator are identified, and a preliminary list of use cases is defined based on relevant literature and input from the HB developer. The simulation approach is conducted to predict key performance indicators for each stakeholder. The Kruskal-Wallis test was employed to sort and scrutinize the simulation outcomes and discern the significance of each use case element. The findings demonstrated that the HB holds the potential to diminish both the operational energy cost by up to 30% for the homeowners and the peak heating load transmitted from the building to the district heating system.

Multi-objective optimization of phase change cooling battery module based on optimal support vector machineoptimal support Vector Machine

An optimization model based on Particle Swarm Optimization-Support Vector Machine(PSO-SVM) and improved NSGA-II algorithm is established in this paper to balance the heat dissipation performance and lightweight of battery. First, the data set is obtained by orthogonal experiments, and then the PSO-SVM model for predicting the battery heat dissipation performance (maximum temperature and maximum temperature difference) is acquired by optimizing the parameters of the support vector machine through particle swarm optimization. With the goal of improving the battery heat dissipation performance and reducing the system mass, the improved NSGA-II algorithm is used for multi-objective optimization to obtain the Pareto solution set. Results show that the R2 (goodness of fit) of the maximum temperature and maximum temperature difference prediction models are 0.99478 and 0.9787, respectively, which verifies the accuracy of the PSO-SVM model. The maximum temperature, the maximum temperature difference, and the mass of the phase change material are in conflict. The temperature rise and temperature difference of the battery can be effectively controlled by sacrificing the mass of the phase change material. Four optimal solutions were selected by using LINMAP and TOPSIS. Compared with the initial model, the mass of phase change materials was reduced by 34.5 %, 29.5 %, 55.3 %, and 2.5 %. On the premise of meeting the requirements of thermal management performance, the entire system becomes lighter. Based on the four optimal solutions, the decision maker can choose from the Pareto optimal solution set according to different requirements for heat dissipation performance and lightweight.

Prognostic analysis of thermal interface material effects on anisotropic heat transfer characteristics and state of health of a 21700 cylindrical lithium-ion battery module

In this study, a semi-empirical computational heat transfer model has been developed to simulate anisotropic thermal characteristics in nickel-rich rechargeable 21700 lithium-ion battery modules with thermal interface materials. A set of conservation equations were developed and numerically solved using a finite-volume-based computational fluid dynamics technique. Experimental measurements of direct current internal resistance, temperature-dependent open circuit potential, and electrochemical impedance were conducted to obtain thermal and electrical data prior to the development of battery heat generation and performance aging models. Detailed reversible and irreversible heat generation rates in battery modeling could be fully addressed and evaluated from the experimental data for post-extensive numerical analysis. After validating the developed battery models against measured experimental data, further numerical analyses were performed to evaluate the effect of thermal interface materials on the battery module temperatures and the state of health. Numerical results showed that the cooling performance of the battery module was improved by reducing interfacial thermal contact resistances after the thermal interfacing application. Moreover, it was found that the parallel thermal conductivity of the interfacing materials to bottom cooling channels is primarily related to the uniform temperature distribution of the battery module, whereas the vertical thermal conductivity is rather associated with maximum temperature. These features are clearly apparent with increased coolant flow rate and thermal interfacing thickness. Lastly, the state of health of the battery module can be enhanced with improved temperature uniformity and decreased maximum temperature of the module when the thermal interfacing materials are employed.

A J-Type Air-Cooled Battery Thermal Management System Design and Optimization Based on the Electro-Thermal Coupled Model

Air-cooled battery thermal management system (BTMS) is a widely adopted temperature control strategy for lithium-ion batteries. However, a battery pack with this type of BTMS typically suffers from high temperatures and large temperature differences (∆T). To address this issue, this study conducted an electro-thermal coupled model to optimize the flow channel structure for reducing the maximum temperature (Tmax) and ∆T in a battery pack for a “J-type” air-cooled BTMS. The parameters required to predict battery heat generation were obtained from a single battery testing experiment. The flow and heat transfer model in a battery pack that had 24 18650 batteries was established by the Computational Fluid Dynamics software ANSYS Fluent 2020R2. The simulation results were validated by the measurement from the battery testing experiment. Using the proposed model, parameter analysis has been implemented. The flow channel structure was optimized in terms of the duct size, battery spacing, and battery arrangement for the air-cooled BTMS. The original BTMS was optimized to reduce Tmax and ∆T by 1.57 K and 0.80 K, respectively. This study may provide a valuable reference for designing air-cooled BTMS.

Impact of the battery SOC range on the battery heat generation and maximum temperature rise

Impact of the battery SOC range on the battery heat generation and maximum temperature rise

Structure optimization of the battery thermal management system based on surrogate modeling of approximate and detailed simulations

The battery thermal management system is of critical significance to the safety and efficient operation of lithium-ion batteries (LIBs). In the battery thermal management system, inadequate structure parameters limit the performance of liquid cooling systems. In this article, a two-step surrogate model is constructed to optimize the structure of the liquid cooling system, which balances the performance and cost of the cooling system. The construction procedure of the two-step surrogate model consists of three parts: the generation of the approximate and detailed simulations, the construction and correction of the primary model, and the accuracy verification of the secondary model. The two-step surrogate model balances the accuracy and the spent resources, by using a large number of approximate simulations and just a few detailed simulations. Compared with the conventional single-step surrogate model, the time required to construct the two-step surrogate model is reduced by 1024 min, although the mean absolute error is increased just marginally from 0.3334°C to 0.3696°C. The cold plate structure optimization under different working conditions is completed by combining the second-generation non-dominated genetic algorithm. The variation of the flow channel diameter with the working conditions is analyzed. Taking the structure parameters when the maximum temperature is the minimum value as an example, the diameter of the flow channel decreases drastically with the increase of the battery heat generation rate at the beginning, and finally maintains at 3 mm. Moreover, the flow channel diameter tends to increase linearly with the increase of coolant flow rate.

Research on fast-charging battery thermal management system based on refrigerant direct cooling

Aiming at the problem of high battery heat generation during the super fast-charging process of electric vehicle fast-charging power batteries, this study designs a fast-charging battery thermal management system based on the refrigerant direct cooling architecture. In order to use the refrigerant of refrigerant to cool the battery quickly. Firstly, the study constructs the heat generation model of the power battery, the calculation model of the battery thermal management system, and builds the experimental device. Secondly, theoretical simulations and experimental studies were conducted for low-temperature fast-charging and high-temperature fast-charging operating conditions. The experimental results show that the designed battery thermal management system has good cooling effect and temperature uniformity.

A design optimization method for solar-driven thermochemical storage systems based on building performance simulation

The challenge of the temporal mismatch between energy supply and demand in buildings is growing with the increasing share of renewable energy in total energy consumption. Among all the state-of-the-art energy storage solutions, thermochemical heat storage shows a unique potential thanks to its considerable energy density, acceptable cost, and negligible heat loss. For this reason, it becomes a promising alternative to common sensible heat storage solutions for building applications. The integration of such a novel technology in buildings necessitates a method for the assessment of its potential impact and benefit, the comparison to common alternatives, and the optimization of the system design. This work proposes a method based on modeling and simulation of the interaction between the thermochemical heat storage system and the building using a data-driven surrogate model of the storage system in combination with a building performance simulation engine. The data-driven model was developed and validated based on laboratory measurements of a novel closed-loop thermochemical heat storage system, the heat battery (HB). The method was demonstrated in a case study to identify the optimal size of the HB in a solar-driven configuration based on a residential building use case. The results show that the heat battery can digest the thermal energy transferred from the solar thermal collector to reduce the original electricity consumption for heating the detached house (0.7 MWh to 1.0 MWh in considered cases) without any obvious sacrifice in thermal comfort and that the small-scale HB (with a storage volume below 160 l) shows efficient usage of the designed storage capacity.

A hybrid battery thermal management system coupling with PCM and optimized thermoelectric cooling for high-rate discharge condition

The lithium-ion battery is now abundantly available in the market due to its excellent performance. However, battery overheating is increasingly prominent when the battery discharges at high speed. In this study, an active-passive BTMS (Battery Thermal Management System) combining PCM (Phase Change Material) and TEC (Thermoelectric Cooler) was proposed. The effects of different TEC currents and delayed cooling at different PCM melting rates were analyzed under the 4C discharge condition to enhance the thermal performance. The results demonstrate that battery temperature gets effectively controlled as the TEC current increases, but the temperature difference and PCM utilization are poor. However, applying a delayed current after the PCM melting rate reaches 80% reduces energy consumption and provides better temperature uniformity. Considering the large battery heat under 4C discharge, combined with the transient supercooling effect of TEC, a continuous pulse current was used to provide additional cooling power. Results show that the battery with TEC pulsed current operates 57.8% longer at 40 °C with a temperature difference maintained at 2.5 K under 4C discharge conditions compared with the PCM model.

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.

Cooling Performance Optimization of Air‐Cooled Battery Thermal Management System with L‐Type Flow

The development of electric vehicles has driven the refinement of thermal management technology for batteries. Due to the limitations of device locations during operation, battery thermal management systems (BTMS) with diverse geometric configurations should be considered. Herein, optimization of the L‐type air‐cooled structures (L(A) and L(B)) is performed with the objective of minimizing the maximum temperature difference while avoiding increasing system power consumption. The simulation indicates that optimization of the plenum angle is more effective than the widths of the divergence and convergence plenums for the BTMS L(A). Multivariate optimization of angle and widths decreases maximum temperature (Tmax) by 1.79 K and maximum temperature difference (ΔTmax) by 2.45 K compared to the original BTMS. The adjustment of BTMS L(B) takes place in three aspects: plenum widths, inlet position, and baffle setting. Among these, optimizing the plenum widths proves to be the most efficient method. The Tmax and ΔTmax decrease by 1.41 and 2.13 K, respectively, and the power consumption decreases by 11.30% compared to the original BTMS. The optimal systems display improved cooling performance under varying battery heat generation rates and air flow rates, demonstrating the effectiveness of the optimization methods in enhancing cooling efficiency.

Novel Battery-Supercapacitor Hybrid Energy Storage System for Wide Ambient Temperature Electric Vehicles Operation

Electric vehicles (EVs) are gaining popularity in recent days to reduce the dependency on fossil fuels. Batteries are the main power source in EVs. However, the capacity of the battery degrades when it operates in low temperatures (< 0∘C). Hence, it is essential to maintain the battery temperature (> 0∘C) to operate at maximum capacity. Additionally, the battery alone is not suitable to supply the high transient power requirements of EVs. Thus, this paper proposes a novel integrated converter topology, which facilitates battery heating along with power transfer from the hybrid energy storage (battery and supercapacitors). The internal ac heating uses a resonant network for uniform heating of the battery cells in heating mode. The same inductor of the resonant network is also used for power transfer from hybrid energy storage during the driving mode. The Discrete Fourier Transform (DFT) based integrated inductor design ensures effective EV power sharing between battery and supercapacitors and reduces battery heating time. Thus, the proposed integrated converter reduces the number of converters stages, control complexity and overall cost. The detailed analysis and design are included along with the simulation and experiment results. The results show the uniform internal heating of the battery and efficient power transfer from/to the battery and supercapacitors. The experimentation is performed in a 1kW system considering the European driving cycle.

Temperature Simulation and Analysis of Power Lithium-ion Battery Module Based on Two-dimensional CFD Thermal Model

The power lithium battery generates a lot of heat during working, whose heat dissipation performance will directly affect its working performance and safety. In order to study the heat dissipation characteristics of lithium batteries, In this paper, a battery module structure based on phase change material(PCM) was designed, and a two-dimensional battery heat generation model and a heat transfer model based on PCMs were established. Then, the geometric model, grid division and grid size correlation verification were carried out using ANSYS simulation software. Under comprehensive consideration of computational efficiency and accuracy, 0.5mm was selected as the grid division size. Finally, for the charging and discharge cycle, the temperature field of the battery module based on composite phase change material(CPCM) composed of pure graphite material and expanded graphite, and paraffin is simulated respectively. At the same time, the influence of ambient temperature on the heat dissipation performance of battery module with PCM was studied. when the ambient temperature is set to be 17°C, 27 °C and 37 °C respectively, the maximum temperature of the battery module base on PCM is 199°C, 211°C and 223°C respectively, and the maximum temperature difference is 162°C, 164°C and 165 °C respectively. The results show that the heat dissipation performance of the battery module with CPCM is better than that of PCM under cycle conditions. What’s more, the higher the ambient temperature is, the higher the temperature of the battery module is. The research results in this paper can provide a certain reference for the thermal management design of the battery.

Research on the Application of Industrial Robot Surface Grinding and Polishing Technology in Lithium Battery Cooling Shell

In modern intelligent manufacturing, when using industrial robots to complete precision machining of lithium battery heat dissipation housing materials such as assembly, grinding, polishing, and deburring, it is not only necessary to track the position of the robot’s end effector, but also to consider the contact force generated when the actuator contacts the working environment. This project takes the research on position and force control in robot automatic polishing process as the starting point. Due to the uncertainty and high degree of nonlinearity in the control process, machine vision is introduced into the process of robotic precision machining systems, combining visual inspection systems and feedback control systems to achieve grinding trajectory planning, verify the feasibility of the control scheme, and develop a robotic lithium battery housing material processing experimental platform to meet the requirements for precision machining of the free surface of the lithium battery heat dissipation workpiece, The surface roughness parameters of the lithium battery heat dissipation workpiece after precision machining by the robot should meet the requirements of the arithmetic mean deviation of the contour.

Design of Injection Mould for Lithium Battery Heat Dissipation Device Connector Bottom Cover

The design process of the injection mould for the Lithium battery heat dissipation device connector bottom cover is described in detail. In the design process, the UG software is used to establish the three-dimensional model of the plastic part, and the mould flow analysis is carried out with the help of the moldflow software to determine the optimal gate position of the plastic part. By determining the injection process parameters of Lithium battery heat dissipation device connector bottom cover material, the design of the cavity layout of the plastic part is completed, and the basic size and mould structure of the mould base are determined. Then, the UG injection mould design guide module was used to carry out the parting design, and the structural design of the mould’s gating system, molding parts, lateral parting mechanism, core-pulling mechanism, ejection mechanism, exhaust system and cooling system was completed in turn. The whole design process improved the efficiency of mould design and saved a lot of time and cost.